hospital training

CHAPTER 1

INTRODUCTION

1.1. Scope of Biomedical Engineering

Biomedical Engineering is the only unique interface between engineering and healthcare in which one can utilize their knowledge of engineering in healthcare to perfection. It involves studying all types of engineering ranging from electronics, computers, mechanical, chemical and nanotechnology.

Biomedical engineers are employed in the industry, in hospitals, in research facilities of educational and medical institutions, in teaching, and in government regulatory agencies. They often serve a coordinating or interfacing function, using their background in both engineering and medical fields. In industry, they may create designs where an in-depth understanding of living systems and of technology is essential.

They may be involved in performance testing of new or proposed products. Government positions often involve product testing and safety, as well as establishing safety standards for devices.

In the hospital, the biomedical engineer may provide advice on the selection and use of medical equipment, as well as supervising its performance testing and maintenance.

They may also build customized devices for special health care or research needs.In research institutions, biomedical engineers supervise laboratories and equipment, and participate in or direct research activities in collaboration with other researchers with such backgrounds as medicine, physiology, and nursing.

Some biomedical engineers are technical advisors for marketing departments of companies and some are in management positions. Some biomedical engineers also have advanced training in other fields. For example, many biomedical engineers also have an M.D. degree, thereby combing an understanding of advanced technology with direct patient care or clinical research.

Some of the well-established specialty areas within the field of biomedical engineering are bioinstrumentation, biomechanics, systems physiology and rehabilitation engineering.

1.2. Introduction about the Hospital

Stanley Medical College (SMC) is a government medical college with hospitals, located in Chennai (Madras) in the state of Tamil Nadu, India. Though the original hospital is more than 200 years old, the medical college was formally established on July 2, 1938. Stanley Medical College is ranked 22nd in the India Today 2014 survey.

Fig 1.1 Stanley Hospital

The medical college and the hospital is considered one of the best state-owned medical facilities and educational institutes in the country, with a Centre of Excellence for Hand and Reconstructive Microsurgery and a separate cadaver maintenance unit, the first in the country. By legacy, the hospital's anatomy department receives corpses for scientific study from the Monegar Choultry from which the hospital historically descended.

History

Stanley Medical College and Hospitals is one of the oldest and well known centers in India in the field of medical education. The seed for this institution was sown as early as 1740 when the East India Company first created the medical department. The renowned Stanley Hospital now stands on the old site of the Monegar Choultry established in 1782. In 1799 the Madras Native Infirmary was established with Monegar Choultry and leper asylum providing medical services.

In 1830, a well-known philanthropist Raja Sir Ramasamy Mudaliar endowed a hospital and dispensary in the Native Infirmary. In 1836, Madras University established M.B. & G.M. and L.M & S Medical Courses in the Native Infirmary. In 1903, a hospital assistant course was introduced with the help of the East India Company. In 1911, the first graduating class was awarded their Licensed Medical Practitioner (LMP) diplomas.

In 1933, Five Year D.M. & S (Diploma in Medicine & Surgery) course was inaugurated by Lt. Colonel Sir George Fredrick Stanley a British parliamentarian. The school was named after him by the Governor of Madras Presidency on July 2, 1938. In 1941, three medical and surgical units were created. This was expanded to seven medical and surgical units in 1964. In 1938, 72 students studied, and then from 1963, 150 students were admitted each year. In 1964, Dr. Sarvepalli Radhakrishnan, the President of India, laid the foundation stone for College Auditorium to mark Silver Jubilee Celebration.

In 1990, the Institute of Social Pediatrics was established. Initially established as a centre for children and for improving research programmes, the institute today houses several departments of the hospital including nephrology, dermatology, and neurology and provides treatment for adult patients from Stanley.

Description

The College is associated with the well-known Government Stanley Hospital which has 1280 beds for in-patient treatment. The hospital has an out-patient attendance of around 5000 patients per day. A unique feature is its 8-story surgical complex equipped to perform up to 40 surgeries simultaneously, and a separate pediatrics block with all specialties under one roof. RSRM hospital is also attached for obstetrics and Gynecology care. And a modern 7 storey medicine complex under construction expected to be completed in 2013.

The three well known departments of the Stanley Medical Hospitals are Surgical Gastroenterology, Urology and the Institute of Hand Rehabilitation and Plastic Surgery. The Institute for Research and Rehabilitation of Hand and the Department of Plastic Surgery (IRRH & DPS) is one of the best centers in Southeast Asia. The Department of Surgical Gastroenterology was the first in India to perform a successful liver transplant, under the leadership of Dr. R.P. Shanmugam, Surgical Gastroenterologist and the first among Hospitals/ Hospital Departments in India to obtain the ISO 9001 certification. The Department of Urology performs up to fifty kidney transplants a year.

Attached hospitals

• Government Stanley Hospital, Chennai 600 001
• Government Raja Sir Ramasamy Mudaliar Lying-in Hospital, Chennai 600 13
• Government Hospital for Thoracic Medicine, Tambaram, Chennai 600 047
• Government Peripheral Hospital, Tondiarpet, Chennai 600 081

CHAPTER 2

Departments Visited

·        Central Sterilization & Supply Department(CSSD)

·        Central Lab

                                                       i.            Pathology Lab

                                                     ii.            Biochemistry Lab

·        Radiology

                                                       i.            Radio diagnosis

                                                     ii.            Radiotherapy

·        Endoscopy

·        Neurology

·        Nephrology

·        Blood Transfusion Medicine

·        Cardiology

·        Neonatal

·        Casualty

·        ICU

·        OT

2.1. CSSD

The Central Sterile Supply Department within a hospital receives stores, sterilizes and distributes to all departments including the wards, outpatient department [OPD] and other special units such as operating theatre [OT]. Major responsibilities of CSSD include processing and sterilization of syringes, rubber goods [catheters, tubing], surgical instruments, treatment trays and sets, dressings etc. it is also responsible for economic and effective utilization of equipment resources of the Hospital under controlled supervision.

2.1.1. Equipment in CSSD

1.     Autoclave: It sterilizes medical equipment by using steam or gas.

2.     EtO Sterilizer: It used to sterilize medical and pharmaceutical products that cannot support conventional high temperature steam.

2.2. Central Lab

2.2.1. Pathology Lab

Pathology is a branch of medical science primarily concerning the examination of organs, tissues, and bodily fluids in order to make a diagnosis of disease. This lab concerns the laboratory analysis of blood, urine and tissue samples to examine and diagnose disease. Typically, laboratories will process samples and provide results concerning blood counts, blood clotting ability or urine electrolytes, for example.

2.2.1.1. Equipment in Pathology Lab

1.     3 part Analyzer: It counts the RBC, Platelets and some types of WBC present in the blood.

2.     5 part Analyzer: It counts all blood cells present in the blood.

2.2.2. Biochemistry Lab

Biochemistry is a science which involves the examination of various chemical processes as they are found in living organisms. They are mainly used for performing various biochemical tests on blood using an automated biochemistry analyzer.

2.2.2.1. Equipment in Biochemistry Lab

1.     Auto analyzer: It performs many biochemistry tests through automation.

2.3. Radiology

2.3.1. Radiodiagnosis

This department is concerned with the diagnosis of various diseases by medical imaging techniques using radiation or magnetic resonance.

2.3.1.1. Equipment in Radiodiagnosis

1.     X-Ray Machine: It uses X-Rays to image hard tissues of the body.

2.     Mammography: It uses X-Rays to image breasts to detect tumor or calcifications.

3.     CT Scanner: It also uses X-Ray images taken from different angles and uses computer processing to create cross-sectional images, or slices, of the bones, blood vessels and soft tissues inside your body.

4.     MRI Scanner: It uses a magnetic field and pulses of radio wave energy to produce pictures of organs and structures inside the body.

2.3.2. Radiotherapy

Radiotherapy uses radiation, such as x-rays, gamma rays, electron beams or protons, to kill or damage cancer cells and stop them from growing and multiplying. It is a localized treatment, which means it generally only affects the part of the body where the radiation is directed.

2.3.2.1. Equipment in Radiotherapy

1.     Cobalt-60 Machine: It emits radiation to treat cancerous cells.

2.4. Endoscopy

The Endoscopy Department offers a complete range of high-quality diagnostic and therapeutic endoscopic services. Endoscopy is the term that is used to describe the direct visual examination of any part of the inside of the body that can be reached through a natural orifice.

2.5. Neurology

Neurology is the branch of medicine that deals with the diagnosis and treatment of disorders of the nervous system, which includes the brain and spinal cord. It involves EEG, ENMG, etc.

2.5.1. Equipment in Neurology

1.     EEG: It measures the electrical activity of the brain.

2.     NCV: It measures the nerve conduction velocity of the nerve in test.

2.6. Nephrology

Nephrology is the branch of internal medicine devoted to the study, diagnosis, and treatment of kidney disease. The Dialysis units are under the control of Nephrology Department.

2.6.1. Equipment in Nephrology

1.     Dialyzer: It removes waste and excess water from the blood and is used primarily as an artificial replacement for lost kidney function in people with kidney failure.

2.7. Blood Transfusion Medicine

Blood Transfusion medicine (or transfusiology) is the branch of medicine that is concerned with the transfusion of blood and blood components. The blood bank is the section of the clinical laboratory where medical technologists process and distribute blood products. Blood Transfusion Medicine involves blood product selection and management, immunohematology, apheresis, stem cell collection, cellular therapy, and coagulation. 

2.7.1. Equipment in Blood Transfusion Medicine

1.     Apheresis Machine: It separates out one particular constituent of the blood and returns the remainder to the circulation of the donor.

2.     Centrifuge: It involves the use of the centrifugal force for the sedimentation of heterogeneous mixtures.

2.8. Cardiology

The Department of Cardiology provides a broad range of services in the diagnosis and management of heart disease. The field includes medical diagnosis and treatment of congenital heart defects, coronary artery disease, heart failure, valvular heart disease and electrophysiology.

2.8.1. Equipment in Cardiology

1.     Heart Lung Machine: It is a machine which carries out the functions of the heart and the lungs during cardiopulmonary bypass surgeries.

2.     TMT: It is a stress test for monitoring the heart’s function.

3.     ECG: It measures the electrical activity of the heart.

4.     Echocardiograph: It uses standard two-dimensional, three-dimensional, and Doppler ultrasound to create images of the heart.

2.9. Neonatal

Neonatal units specialize in the care of babies born early, with low weight or who have a medical condition that requires specialized treatment. The services combine dedicated medical and nursing care with advanced life-supporting equipment.

2.9.1. Equipment in Neonatal

1.     Warmer: It is used to maintain the body temperature of babies.

2.     Phototherapy: It is used in the treatment of jaundice by passing UV light.

3.     Incubator: It is an enclosed apparatus in which premature or unusually small babies are placed and which provides a controlled and protective environment for their care.

2.10. Casualty

Staffed and equipped to provide rapid and varied emergency care, especially for those whoare stricken with sudden and acute illness or who are the victims of severe trauma. The emergency department may use a triage system of screeningand classifying clients to determine priority needs for the most efficient use of available personnel and equipment. Also called emergency room.

2.10.1. Equipment in Casualty

1. C-Arm: It uses X-Rays to image parts of the body during surgery.

2.11. ICU

An intensive care unit (ICU), also known as an intensive therapy unit or intensive treatment unit (ITU) or critical care unit (CCU), is a special department of a hospital or health care facility that provides intensive care medicine.

2.11.1. Equipment in ICU

1.     Ventilator: It is used in cases where the patient is unable to breathe voluntarily.

2.     Multipara Monitor: It monitors various parameters of the body such as temperature, pulse rate, oxygen saturation, etc.

3.     Infusion Pump & Syringe Pump: They are used to deliver a particular volume of fluid at a particular rate.

2.12. OT

An operating theatre is where certain invasive surgical procedures that is operations that involve cutting into and working inside a patient’s body - take place. This might involve either minimally invasive procedures like keyhole surgery – where cameras and a laparoscope are inserted through small incisions – or open surgery where surgeons make larger cuts to reach the internal organs. Complicated operations can last many hours.

2.12.1. Equipment in OT

1.     OT Lights: These are specially designed lights for providing illumination during surgery.

2.     Boyle’s Apparatus: It is a combination of anesthesia machine and a ventilator.

3.     Diathermy: It is used for cutting and coagulation of tissue during surgery.

4.     Defibrillator: It applies electric current to the heart when it fibrillates. 

                                                                                                        

CHAPTER 3

MAJOR EQUIPMENTS

3.1 INTRODUCTION

Medical equipment is designed to aid the diagnosis, monitoring or treatment of medical conditions. These devices are usually designed with rigorous safety standards. In this chapter equipment are explained in detail.

3.2. CSSD

The Central Sterile Supply Department within a hospital receives stores, sterilizes and distributes to all departments including the wards, outpatient department [OPD] and other special units such as operating theatre [OT]. Major responsibilities of CSSD include processing and sterilization of syringes, rubber goods [catheters, tubing], surgical instruments, treatment trays and sets, dressings etc. it is also responsible for economic and effective utilization of equipment resources of the Hospital under controlled supervision.

3.2.1. Autoclave

An autoclave is a device used to sterilize equipment and supplies by subjecting them to high pressure saturated steam at 121 °C for around 15–20 minutes depending on the size of the load and the contents. Autoclaves are widely used in microbiology, medicine, podiatry, body piercing, veterinary science, mycology, dentistry, and prosthetics fabrication. They vary in size and function depending on the media to be sterilized. Typical loads include laboratory glassware, other equipment and waste, surgical instruments and medical waste.

A medical autoclave is a device that uses steam to sterilize equipment and other objects. This means that all bacteria, viruses, fungi, and spores are inactivated. Medical autoclave uses the temperature ranging from 121°C to 134°C. Autoclaves are found in many medical settings, laboratories, and other places that need to ensure the sterility of an object. Autoclaving is often used to sterilize medical waste prior to disposal in the standard municipal solid waste stream.

Autoclave has become more common as an alternative to incineration due to environmental and health concerns rose because of the combustion by-products emitted by incinerators, especially from the small units which were commonly operated at individual hospitals. The image of the medical autoclave is shown in figure 3.1.

Fig. 3.1 Autoclave

3.2.1.1. Principle

The principle in auto clave is sterilizing the material using steam and pressure. At very high temperature and pressure the water content is absorbed and with absence of water the microbes die thus sterilizing the material. The principle is basically same as that in an ordinary pressure cooker. However the temperature and pressure used is higher. Reverse osmosis water is used for this purposes.

The boiling point of water at normal atmospheric pressure is 100^oC. When the free-flowing steam at a temperature of 100^oC is subjected under pressure of 1 atmosphere above the sea-level pressure i.e., 15 pounds pressure per square inch, the temperature inside the autoclave happens to rise up to 121^oC, which is an usual and common parameters employed in the moist heat sterilization.

3.2.1.2 Working

The working of autoclave is depicted using the figure 3.2 given below; the working of the autoclave is similar to the working of the pressure cooker. The working is as follows first steam enters the chamber jacket, passes through an operating valve and enters the rear of the chamber behind a baffle plate. It flows forward and down through the chamber and the load, exiting at the front bottom. A pressure regulator maintains jacket and chamber pressure at a minimum of 15 psi, the pressure required for steam to reach 121 Deg C. Overpressure protection is provided by a safety values. The conditions inside are thermostatically controlled so that heat (more steam) is applied until 121C is achieved, at which time the timer starts, and the temperature is maintained for the selected time.

The indicator is used to validate the autoclaving process. Stick-on tape indicators can only be used to verify that the autoclave has reached normal operating temperatures for decontamination but not that the run was long enough. Biological indicators can be used in the efficacy testing of the autoclave process to effectively sterilize the contents being treated. The change in the color of the indicator shows that the sterilization is done.

Biological indicators are done once in a week in order to check the microbial growth in the autoclave. Pressure regulator is also used in the autoclave in order to control the pressure and to set the minimum pressure needed. Reverse osmosis water is mainly used in this autoclave. Table 3.1 shows the specifications of autoclave.

Fig. 3.2Working of Autoclave

Table 3.1 Technical Specifications of Autoclave

S.No	Parameter	Specification
1	Electricity	3 phase 440v
2	Boiler capacity	400 liters
3	Temperature	1210C-1340C
4	Shape	Rectangle
5	Pressure	1.5 kg/cm2

3.2.2. EtO Sterilizer

It is a type of gas sterilizer which uses ethylene oxide gas for sterilization.. Mainly the medical materials made up of glass and plastic is sterilized using gas sterilizer. The medical gas sterilizer is shown in the figure3.3.

Fig. 3.3 EtO Sterilizer

3.2.2.1 Principle

The ethylene oxide molecule is able to react with the carboxyl, amidogen, hydroxyl on gene protein which is necessary for metabolism in cell of bacteria, produce alkylation reaction, replace the unstable hydrogen atom on the groups mentioned above and compose with ethoxyl. Because the compound destroys the Reaction group necessary for the important metabolic reaction of microorganism affects the function of bacterial enzyme and makes microorganism dead.

3.2.2.2. Working

Ethylene oxide sterilization is a chemical process consisting of four primary variables: gas concentration, humidity, temperature and time. Ethylene oxide is an alkylating agent that disrupts the DNA of microorganisms, which prevents them from reproducing. EO sterilization assures that a safe and sterile product will be delivered to the market each and every time.

The ethylene oxide sterilization process may take place within a traditional ethylene oxide (EO or EtO) sterilization cycle. It consists of three processing phases.

• Pre-conditioning: Used to preheat and humidify product loads to predefined conditions. This will assure a repeatable EO sterilization process regardless of pre-processing load storage conditions
• Sterilization: Performed using process phases specifically designed to provide the required level of ethylene oxide exposure to assure sterility for a device or family of devices
• Aeration: Used to accelerate out gassing of exposed product loads and to contain and eliminate residual ethylene oxide emissions.

Fig. 3.4 Block Diagram of EtO Sterilizer

Table 3.2 Technical Specification of gas sterilizer

S.No	Parameter	Specification
1	Electrical Requirement	220v /380v 50Hz;60 Hz
2	Temperature  Range	40~60°C
3	Chamber volume	124 liters
4	Net weight	490 kg

3.3. Central Lab

3.3.1. Auto analyzer

          The Auto Analyzer is an automated analyzer using a flow technique called continuous flow analysis (CFA), first made by the Technicon Corporation. The instrument was invented 1957 by Leonard Skeggs, PhD and commercialized by Jack Whitehead's Technicon Corporation. The first applications were for clinical analysis, but methods for industrial analysis soon followed. The design is based on separating a continuously flowing stream with air bubbles.

Fig. 3.5 Auto Analyzer

3.3.1.1. Principle

          In continuous flow analysis (CFA) a continuous stream of material is divided by air bubbles into discrete segments in which chemical reactions occur. The continuous stream of liquid samples and reagents are combined and transported in tubing and mixing coils. The tubing passes the samples from one apparatus to the other with each apparatus performing different functions, such as distillation, dialysis, extraction, ion exchange, heating, incubation, and subsequent recording of a signal. An essential principle of the system is the introduction of air bubbles. The air bubbles segment each sample into discrete packets and act as a barrier between packets to prevent cross contamination as they travel down the length of the tubing. The air bubbles also assist mixing by creating turbulent flow (bolus flow), and provide operators with a quick and easy check of the flow characteristics of the liquid. Samples and standards are treated in an exactly identical manner as they travel the length of the tubing, eliminating the necessity of a steady state signal, however, since the presence of bubbles create an almost square wave profile, bringing the system to steady state does not significantly decrease throughput (third generation CFA analyzers average 90 or more samples per hour) and is desirable in that steady state signals (chemical equilibrium) are more accurate and reproducible.

          A continuous flow analyzer (CFA) consists of different modules including a sampler, pump, mixing coils, optional sample treatments (dialysis, distillation, heating, etc.), a detector, and data generator. Most continuous flow analyzers depend on color reactions using a flow through photometer, however, also methods have been developed that use ISE, flame photometry, ICAP, fluorometry, and so forth.

3.3.1.2. Components

Auto sampler

          The sampler consists of a sample tray and a metal probe. The sample tray holds the cups that the sample is poured into. The tray on this model can hold up to 40 cups. The loaded sample tray rotates and the metal probe dips into each cup and aspirates a portion (1ml or less) of the contents for a given time interval. The probe rapidly lifts out of the cup, aspirates air for approximately one second, and goes into a wash receptacle where diluents water is aspirated. The sampler wheel determines the speed of the sampler and the ratio of sample to rinse.

Proportioning pump

          The pump consists of two parallel stainless steel roller chains that carry transverse steel rollers which bear continuously against a spring-loaded platen surface. The platen surface applies pressure to the tubes on the rollers which squeeze the various fluids ahead of them into the system in the exact proportions required by the test. The pump also has a high speed but it is only used for washing out the system after the samples are run if you are in a hurry.

Manifold

          The manifold brings together samples and reagents so a reaction can occur and a desired analysis may be performed. Chemicals are mixed by segmented air bubbles in the manifold to form the color complexes necessary for the specific procedure or determination. If a cadmium column is used, air bubbles are introduced into the system then taken out before reaching the column and reintroduced after the column.

Photo colorimeter

          The colorimeter measures the intensity and the amount of the light absorbed as the liquid phase flows along the optical path and the phototubes. The filter used also depends on which assay is run. The colorimeter measures absorbance by either direct or inverse operation. In the direct operation the analytical stream undergoes a color producing reaction and in the inverse operation the analytical stream undergoes a color reducing reaction. The absorbance is higher in the direct operation which also means the concentration of the sample is higher and vice versa for the indirect operation.

3.3.1.3. Working

1. Turn on the lamp in the colorimeter. It must warm up for 15 minutes.

2. Lock the tubing into the end blocks and make sure the tubing is taut.

3. Latch the platen surface over the pump tubes and rollers and then turn the pump on. At this point it is running diluents water through the sample probe and diluents solution through the reagent tubes.

4. Check tubing for loose connections and leaks.

5. Start placing the proper tubes into the reagent bottles, one at a time and letting them run through the system for a while before adding the next reagent. Note: The color reagent is the last reagent to enter the system.

6. An even bubble pattern must be achieved before starting the run by letting the reagents run through the system and warm up. This is very important.

7. If a column is being used, a freshly packed column must have the nitrate reagents flowing through it for 20 minutes before starting the run, a reused column only needs 5 to 10 minutes. It is very important to have an even bubble pattern before putting on the column. To attach the column to the manifold, connect the inward flow of the column first, and then the outward flow.

8. Pour the standards, a blank and the samples into the cups and place in the tray while waiting for the machine to warm up.

9. Make sure the correct sampler wheel is installed in the sampler for the specific assay. The sampler wheel determines the speed of the sampler and the ratio of sample to reagents.

10. Turn the sampler "on".

11. Depending on which assay is being performed, the first standard may need to be calibrated. If this is the case, there is a calibration knob on the colorimeter.

Fig. 3.6 Schematic diagram

3.3.1.4. Technical Specification

Company: Beckman Coulter

Model: Au 480

Table 3.3 Technical specification of Auto analyzer

S.No	Parameter	Specification
1.	Sample feeder capacity	80 samples
2.	Sample type	Plasma, Serum, Urine.
3.	Power supply	100–240v; 60 Hz
4.	Dimensions (W x H x D) mm	1,450 x 1,205 x 760
5.	Software	Windows XP®
6.	Wavelength	between 340 – 800 nm
7.	Reaction time	Up to 8 minutes

3.4. Radiology

3.4.1. X-Ray Machine

X-rays themselves are actually a form of radiation closely related to visible light, infrared and ultraviolet radiation. X-ray radiation is very similar to visible light but with a much higher energy level. The generation of X-rays are shown in the figure 3. a. This elevated energy level allows x-rays to easily penetrate less dense materials (such as clothing, plastic or skin) and pass through to the other side. However, materials of a more dense nature absorb some or all of the radiation hitting them. Therefore when objects composed of materials of varying densities (e.g. human bodies) are exposed to x-rays, the shadows produced mimic these density variations.

Fig. 3.7 BlockDiagram of X-Ray Machine

Fig. 3.8 X-Ray Image and Machine

Fig. 3.9 X-Ray Generation

Table 3.4 Technical Specifications of X-Ray

S.No	Parameter	Specification
1	Power Supply	440V+10%V ac,50Hz,3 phase
2	Exposure Time	5sec to 30 minutes
3	Tube Cooling	Oil cooled supported by water cooling system
4	High Voltage Cables	15m long with PVC housing
5	Focal Spot Size	Dual focus 0.8x0.8mm & 3.5x3.5mm

3.4.2. Mammography

A Mammogram is a special type of X-ray of the breasts which is used as a diagnostic and a screening tool. Early detection of breast cancer, typically through detection of characteristic masses and/or micro calcifications before they are big. Mammography recommended for women who have symptoms of breast cancer or who have a high risk of the disease.

3.4.2.1. Principle

Low energy X-rays are produced by the x-ray tube (an evacuated tube with an anode and a cathode) when a stream of electrons, accelerated to high velocities by a high-voltage supply from the generator, collides with the tube’s target anode. The cathode contains a wire filament that, when heated, provides the electron source. The target anode is struck by the impinging electrons. X-rays exit the tube through a port window of beryllium. Additional filters are placed in the path of the x-ray beam to modify the x-ray spectrum. The x-rays that pass through the filter are shaped by either a collimator or cone apertures and then directed through the breast.

Mammography has a false-negative (missed cancer) rate of at least 10 percent. This is partly due to dense tissues obscuring the cancer and the fact that the appearance of cancer on mammograms has a large overlap with the appearance of normal tissues. A meta-analysis review of programs in countries with organized screening found 52% over-diagnosis. The block diagram of mammography machine is shown in Fig 3.10

Fig. 3.10 Block Diagram of Mammography

3.4.3. Cobalt-60

Cobalt therapy or cobalt-60 therapy is the medical use of gamma rays from cobalt-60 radioisotopes to treat conditions such as cancer. Cobalt (chemical symbol Co) is a metal that may be stable (non-radioactive, as found in nature), or unstable (radioactive, man-made).The most common radioactive isotope of cobalt is cobalt-60.The cobalt-60 isotope undergoes beta decay with a half-life of 5.24 years.Cobalt-60 therapy is painless. Patients who are treated with cobalt-60 therapy have fewer side effects than patients who are treated with conventional radiation therapy.

Principle and Working

Cobalt-59 is irradiated with neutrons in a reactor to form unstable cobalt-60.It undergoes beta decay to produce nickel-60 and emits 2 gamma rays of about 1MeV. These gamma rays are targeted towards the cancerous cells with the help of lasers.

Fig.3.11 Radiotherapy

3.5. Endoscopy

The Endoscopy Department offers a complete range of high-quality diagnostic and therapeutic endoscopic services.  Endoscopy is the term that is used to describe the direct visual examination of any part of the inside of the body that can be reached through a natural orifice.

3.5.1. Endoscope

Endoscopy means looking inside and typically refers to looking inside the body for medical reasons using an endoscope, an instrument used to examine the interior of a hollow organ or cavity of the body. Unlike most other medical imaging devices, endoscopes are inserted directly into the organ.

A lighted optical instrument used to get a deep look inside the body and examine organs such as the throat or esophagus. An endoscope can be rigid or flexible.

Specialized endoscopes are named depending where they are intended to look. Examples include: cystoscope (bladder), nephroscope (kidney), bronchoscope (bronchi), laryngoscope (larynx + the voice box), otoscope (ear), arthroscope (joint), laparoscope (abdomen), and gastrointestinal endoscopes.

There are many different types of endoscope, and depending on the site in the body and the type of procedure, endoscopy may be performed by a doctor or a surgeon, and the patient may be fully conscious or anaesthetized.

Principle

There are several different types of endoscope. Each one is designed to investigate a specific part of the body. Endoscopes may be rigid or flexible, although most endoscopes in routine use are flexible. The two types differ in appearance, but function in similar ways. Both use light to magnify and view the internal structures of the body.

Flexible endoscopes are useful for looking at the digestive and respiratory tracts because they bend in places. They use fiber optics to shine light into the body. Fiber optics are thin strands of glass or plastic that transmit light by reflecting it. Water and air, as well as surgical instruments that may be necessary to take a tissue sample, can also be passed along the hollow center of the endoscope.

Flexible endoscopes have a tiny camera attached to the end. The view recorded by the camera is displayed on a computer screen for the doctor, and sometimes the patient, to see.

Rigid endoscopes are usually much shorter than flexible endoscopes. They are often used to look at the surface of internal organs, and may be inserted through a small cut in the skin. Gas or fluid is sometimes used to move the surface tissues of organs in order to see them more clearly. Rigid endoscopes are commonly used to examine the joints.

Fig 3.12 Endoscope

Working

It is often necessary to inspect a region inside a confined area. In medicine, an endoscope is used to look inside the body to examine organs. Endoscopes can examine gastro-intestinal, respiratory and urinary tracts as well as internal organs through a small incision. An endoscope captures images through its long tube, which can be rigid or flexible.  Additional instruments for cutting, grasping and other functions are often attached to the endoscope to permit minimally invasive procedures that improve patient care and minimize recovery time. When used in a technical application to inspect confined spaces, it is often referred to as a borescope. Borescopes are used to inspect machinery interiors, building walls and to search for victims in collapsed buildings.

Endoscopes, or borescopes, have three basic requirements in common:

·        A light source and tube are used to guide the light to the subject A light source to illuminate the subject

·        A tube to guide the light to the subject

·        A lens or fiber optic system to capture light reflected from the subject

·        An image-capture system to capture, process and store or display the image

·        TI’s broad product portfolio supports the entire image chain: generating light, capturing an image, signal conditioning and image processing.

LED drivers supply a bright light source with excellent directionality and minimal waste heat. These drivers are versatile and permit selection of LEDs optimized for an application’s spectral requirements. The resolution of current steps impacts the precision of the illumination control; 14-bit LED controllers allow for precise control of illumination levels and illumination timing.

The image sensor detects the reflected light and converts the light to an analog electrical signal. Depending on the image sensor’s location, low-noise line drivers may be needed to transmit the signal over the light tube’s length. Critical considerations for line drivers are low power, noise immunity and data rate. LVDS technology provides up to 800Mbps with voltage swings of a few tenths of a volt and high rejection of common-mode noise.

Essential to the final image quality is the Analog Front-End, AFE. The AFE conditions the sensor’s analog electrical signal and converts image information to a digitized representation. Critical to AFE selection is the ability to condition the signal to correct sensor-induced distortions such as: dark current cancellation; reset level variations; defective pixel correction; and DC off-set variations. Depending on the signal level, the presence of Programmable Gain Amplifiers (PGAs), the linearity of the PGAs and the range of gains available may also be important. During digitization, the number of bits will determine the contrast of the image. Typically, one wants to digitize the initial data with two to four bits more precision than is desired in the final image. Thus, if 8-bits of final image data are required, then initially digitize to 10-bits to allow for rounding errors during image processing. Finally, when color reproduction is critical, then the Differential and Integral Non-Linearity (DNL, INL) should be minimized.

3.6. Neurology

Neurology is the branch of medicine that deals with the diagnosis and treatment of disorders of the nervous system, which includes the brain and spinal cord. It involves EEG, ENMG, etc.

3.6.1. EEG

Electroencephalography (EEG) is the recording of electrical activity along the scalp. EEG measures voltage fluctuations resulting from ionic current flows within the neurons of the brain. In clinical contexts, EEG refers to the recording of the brain's spontaneous electrical activity over a short period of time, usually 20–40 minutes, as recorded from multiple electrodes placed on the scalp. Diagnostic applications generally focus on the spectral content of EEG, that is, the type of neural oscillations that can be observed in EEG signals. In neurology, the main diagnostic application of EEG is in the case of epilepsy, as epileptic activity can create clear abnormalities on a standard EEG study. A secondary clinical use of EEG is in the diagnosis of coma, encephalopathies, and brain death. A third clinical use of EEG is for studies of sleep and sleep disorders where recordings are typically done for one full night, sometimes more. EEG used to be a first-line method for the diagnosis of tumors, stroke and other focal brain disorders, but this use has decreased with the advent of anatomical imaging techniques with high (<1 mm) spatial resolution such as MRI and CT. Despite limited spatial resolution, EEG continues to be a 61 valuable tool for research and diagnosis, especially when millisecond-range temporal resolution (not possible with CT or MRI) is required. Derivatives of the EEG technique include evoked potentials (EP), which involves averaging the EEG activity time-locked to the presentation of a stimulus of some sort (visual, somatosensory, or auditory).

Fig.3.13 EEG Machine

Wave Pattern

a) Delta is the frequency range up to 4 Hz. It tends to be the highest in amplitude and the slowest waves. It is seen normally in adults in slow wave sleep. It is also seen normally in babies. It may occur focally with sub cortical lesions and in general distribution with diffuse lesions, metabolic encephalopathy hydrocephalus or deep midline lesions. It is usually most prominent frontally in adults (e.g. FIRDA - Frontal Intermittent Rhythmic Delta) and posteriorly in children (e.g. OIRDA - Occipital Intermittent Rhythmic Delta).

b) Theta is the frequency range from 4 Hz to 7 Hz. Theta is seen normally in young children. It may be seen in drowsiness or arousal in older children and adults; it can also be seen in meditation. Excess theta for age represents abnormal activity. It can be seen as a focal disturbance in focal sub cortical lesions; it can be seen in generalized distribution in diffuse disorder or metabolic encephalopathy or deep midline disorders or some instances of hydrocephalus. On the contrary this range has been associated with reports of relaxed, meditative, and creative states.

c) Alpha is the frequency range from 7 Hz to 14 Hz. Hans Berger named the first rhythmic EEG activity he saw as the "alpha wave". This was the "posterior basic rhythm" (also called the "posterior dominant rhythm" or the "posterior alpha rhythm"), seen in the posterior regions of the head on both sides, higher in amplitude on the dominant side. It emerges with closing of the eyes and with relaxation, and attenuates with eye opening or mental exertion. The posterior basic rhythm is actually slower than 8 Hz in young children (therefore technically in the theta range).

d) Beta is the frequency range from 15 Hz to about 30 Hz. It is seen usually on both sides in symmetrical distribution and is most evident frontally. Beta 65 activity is closely linked to motor behavior and is generally attenuated during active movements. Low amplitude beta with multiple and varying frequencies is often associated with active, busy or anxious thinking and active concentratio. It may be absent or reduced in areas of cortical damage. It is the dominant rhythm in patients who are alert or anxious or who have their eyes open.

e) Gamma is the frequency range approximately 30–100 Hz. Gamma rhythms are thought to represent binding of different populations of neurons together into a network for the purpose of carrying out a certain cognitive or motor function.

Fig 3.14 EEG Waves

Table 3.5 Technical Specifications of EEG

S.No	Parameter	Specification
1	Channel	29/40
2	CMRR	>100db at 50 HZ
3	Resolution	20 bits
4	Input for unipolar	166.7 mV
5	Input for bipolar	47.6 mV

3.6.2. NCV

A nerve conduction velocity (NCV) test determines how quickly electrical signals move through a particular peripheral nerve. It is also sometimes known as a nerve conduction study and is used in the diagnosis of nerve damage or nerve dysfunction. The peripheral nerves are the nerves outside the brain and the spinal cord. These nerves help you control your muscles and experience important senses. Healthy nerves send electrical signals more quickly and with greater strength than damaged nerves. For this reason, an NCV is helpful in determining the existence, type, and extent of nerve damage in a patient. The NCV test allows the physician to tell the difference between an injury to the nerve axon (the nerve fiber).

Fig 3.15 NCV

An injury to the myelin sheath—the protective covering surrounding the nerve. It is also useful for telling the difference between a nerve disorder and a condition where nerve injury has affected the muscles. Being able to make these distinctions is important for diagnosis and for determining an appropriate course of treatment. There are no known risks associated with this test.

3.7. Nephrology

Nephrology is the branch of internal medicine devoted to the study, diagnosis, and treatment of kidney disease. The Dialysis units are under the control of Nephrology Department.

3.7.1. Dialyzer

            Dialysis works on the principles of the diffusion of solute and ultra-filtration of fluid across a semi-permeable membrane. Blood flows by one side of a semi-permeable membrane, and a dialysate or fluid flows by the opposite side. Smaller solutes and fluid pass through the membrane. The counter-current flow of the blood and dialysate maximizes the concentration gradient of solutes between the blood and dialysate, which helps to remove more urea and creatinine from the blood. The block diagram of dialyzer is explained.

The concentrations of solutes (for example potassium, phosphorus, and urea) are undesirably high in the blood, but low or absent in the dialysis solution and constant replacement of the dialysate ensures that the concentration of undesired solutes is kept low on this side of the membrane. The dialysis solution has levels of minerals like potassium and calcium that are similar to their natural concentration in healthy blood. For another solute, bicarbonate, dialysis solution level is set at a slightly higher level than in normal blood, to encourage diffusion of bicarbonate into the blood, to act as a pH buffer to neutralize the metabolic acidosis that is often present in these patients.

Dialysis works on the principles of the diffusion of solutes andultra filtration of fluid across a semi-permeable membrane. Diffusion is a property of substances in water; substances in water tend to move from an area of high concentration to an area of low concentration. Blood flows by one side of a semi-permeable membrane, and a dialysate, or special dialysis fluid, flows by the opposite side. A semi permeable membrane is a thin layer of material that contains holes of various sizes, or pores. Smaller solutes and fluid pass through the membrane, but the membrane blocks the passage of larger substances. This replicates the filtering process that takes place in the kidneys, when the blood enters the kidneys and the larger substances are separated from the smaller ones in the glomerulus.

Fig 3.16 Block Diagram of Dialysis

Table 3.6 Technical specifications of Dialysis

S.No	Parameter	Specification
1	Dimensions	1330 x 495 x 340 mm (H x W x D)
2	Weight	80 Kg
3	Power supply	230 V, 50 Hz, 16 A
4	Current consumption	9 A
5	Dialysate	Acetic acid + RO + Bicarbonate
6	Solution ratio	1:34:1.82
7	Trans Membrane Pressure	-400 mmHg (negative value)
8	Membrane	Semi permeable (6 times reusable)

3.8. Blood Transfusion Medicine

Blood Transfusion medicine (or transfusiology) is the branch of medicine that is concerned with the transfusion of blood and blood components. The blood bank is the section of the clinical laboratory where medical technologists process and distribute blood products. Blood Transfusion Medicine involves blood product selection and management, immunohematology, apheresis, stem cell collection, cellular therapy, and coagulation. 

3.8.1. Centrifuge

It is the device using centrifugal force to separate two or more substances of different density, e.g., two liquids or a liquid and a solid. The centrifuge consists of a fixed base or frame and a rotating part in which the mixture is placed and then spun at high speed. One type is used for the separation of the solid and the liquid parts of blood.

Test tubes containing blood specimens are set in the rotating part in holders so arranged that when the rotary motion begins the test tubes swing into a slanted or a horizontal position with the open ends toward the axis of rotation; the heavier, solid part of the blood is thrown outward into the bottom of the tube and the lighter liquid part comes to the top. The centrifuge is shown in figure

Fig 3.17 Centrifuge

Principle

Blood separation is accomplished by sedimentation and can be defined as the partial separation or concentration of suspended solid particles from a liquid by gravity. The rate of sedimentation is a function of liquid viscosity, particle density, particle size, concentration of the solution (fraction of dissolved solids), and the force of gravity. Sedimentation rates can be calculated for any particulate fluid using Stokes Law of Sedimentation. This equation states that at any given “g-force”, the rate of sedimentation of a particle is directly proportional to its size and density and relative to the density of the suspension fluid. To accelerate sedimentation, the effect of gravity is amplified using “centrifugal force” provided by a centrifuge and can be many thousand times the force of gravity.

Separation of cellular constituents within blood can be achieved by a process known as differential centrifugation. In differential centrifugation, acceleration force is adjusted to sediment certain cellular constituents and leave others in suspension. During the process of differential centrifugation of blood, the sample is separated into two phases: a pellet consisting of cellular sediment and a supernatant that may be either cellular or cell-free.

Stokes Law of Sedimentation

Vg = d2 (Þp - Þ1) / 18μ x G

Where Vg = sedimentation velocity, d = particle diameter, Þp = particle density, Þ1= liquid density, G = gravitational acceleration, μ= viscosity of liquid.

Working

A laboratory centrifuge is used to separate small amounts of suspension. Test tubes of suspension are spun around very fast so that the solid gets flung to the bottom. The mixtures are usually spun horizontally in balanced containers.

Table Technical Specification of Centrifuge

S.No	Parameter	Specification
1	Max Capacity	6 x 2,000 ml
2	Max RPM/ RCF	4,500/ 6,498
3	Temperature Control	-20 °C to +40 °C
4	Dimensions (HxWxD)	28.25" x 32" x 40"
5	Weight	793.5 lbs

3.9. Cardiology

The Department of Cardiology provides a broad range of services in the diagnosis and management of heart disease. The field includes medical diagnosis and treatment of congenital heart defects, coronary artery disease, heart failure, valvular heart disease and electrophysiology.

3.9.1. Heart Lung Machine

It is a device used in open heart surgery to support the body during the surgical procedure while the heart is stopped. The heart-lung machine is often referred to as the "pump", and does the work of the heart and lungs during the operation.

 

Fig 3.18 Heart lung machine

In the operating theatre, the heart-lung machine is used primarily to provide blood flow and respiration for the patient while the heart is stopped. Surgeons are able to perform coronary artery bypass grafting, open-heart surgery for valve repair or repair of cardiac anomalies, and aortic aneurysm repairs, along with treatment of other cardiac-related diseases.

The heart-lung machine provides the benefit of a motionless heart in an almost bloodless surgical field. Cardioplegia solution is delivered to the heart, resulting in cardiac arrest (heart stoppage). The heart-lung machine is invaluable during this time since the patient is unable to maintain blood flow to the lungs or the body.

In critical care units and cardiac catheterization laboratories, the heart-lung machine is used to support and maintain blood flow and respiration. The diseased heart or lung(s) is replaced by this technology, providing time for the organ(s) to heal. The heart-lung machine can be used with venoarterial extracorporeal membrane oxygenation (ECMO), which is used primarily in the treatment of lung disease. Cardiopulmonary support is useful during percutaneoustransluminal coronary angioplasty (PTCA) and procedures performed with cardiac catheterization. Both treatments can be instituted in the critical care unit when severe heart or lung disease is no longer treatable by less-invasive conventional treatments such as pharmaceuticals, intra-aortic balloon pump (IABP), and mechanical ventilation with a respirator.

Use of this treatment in the emergency room is not limited to patients suffering heart or lung failure. In severe cases of hypothermia, a patient's body temperature can be corrected by extracorporeal circulation with the heart-lung machine. Blood is warmed as it passes over the heat exchanger. The warmed blood returns to the body, gradually increasing the patient's body temperature to normal.

Tertiary care facilities are able to support the staffing required to operate and maintain this technology. Level I trauma centers have access to this specialized treatment and equipment. Being that this technology serves both adult and pediatric patients, specialized children's hospitals may provide treatment with the heart-lung machine for venoarterial ECMO.

3.9.1.1. Working

Foreign surfaces of the heart-lung machine activate blood coagulation, proteins, and platelets, which lead to clot formation. In the heart-lung machine, clot formation would block the flow of blood. As venous and arterial cannulas are inserted, medications are administered to provide anticoagulation of the blood which prevents clot formation and allows blood flow through the heart-lung machine.

Fig.3.19 block diagram of heart lung machine

Large vessels (veins and arteries) are required for cannulation, to insert the tubes (cannulas) that will carry the blood away from the patient to the heart-lung machine and to return the blood from the heart-lung machine to the patient. Cannulation sites for venous access can include the inferior and superior vena cava, the right atrium (the upper chamber of the heart), the femoral vein (in the groin), or internal jugular vein. Oxygen-rich blood will be returned to the aorta, femoral artery, or carotid artery (in the neck). By removing oxygen-poor blood from the right side of the heart and returning oxygen-rich blood to the left side, heart-lung bypass is achieved.

The standard heart-lung machine typically includes up to five pump assemblies. A centrifugal or roller head pump can be used in the arterial position for extracorporeal circulation of the blood. The four remaining pumps are roller pump in design to provide fluid, gas, and liquid for delivery or removal to the heart chambers and surgical field. Left ventricular blood return is accomplished by roller pump, drawing blood away from the heart. Surgical suction created by the roller pump removes accumulated fluid from the general surgical field. The cardioplegia delivery pump is used to deliver a high potassium solution to the coronary vessels. The potassium arrests the heart so that the surgical field is motionless during surgical procedures. An additional pump is available for emergency backup of the arterial pump in case of mechanical failure.

A pump is required to produce blood flow. Currently, roller and centrifugal pump designs are the standard of care. Both modern designs can provide pulsatile (pulsed, as from a heartbeat) or non-pulsatile blood flow to the systemic circulation.

The roller assembly rotates and engages the tubing, PVC or silicone, which is then compressed against the pump's housing, propelling blood ahead of the roller head. Rotational frequency and inner diameter of the tubing determine blood flow. Because of its occlusive nature, the pump can be used to remove blood from the surgical field by creating negative pressure on the inflow side of the pump head.

The centrifugal pump also has a negative inlet pressure. As a safety feature, this pump disengages when air bubbles are introduced. The centrifugal force draws blood into the center of the device. Blood is propelled and released to the outflow tract tangential to the pump housing. Rotational speed determines the amount of blood flow, which is measured by a flow meter placed adjacent to the pump housing. If rotational frequency is too low, blood may flow in the wrong direction since the system is non-occlusive in nature. Magnetic coupling links the centrifugal pump to the control unit.

A reservoir collects blood drained from the venous circulation. Tubing connects the venous cannulae to the reservoir. Reservoir designs include open or closed systems. The open system displays graduated demarcations corresponding to blood volume in the container. The design is open to atmosphere, allowing blood to interface with atmospheric gasses. The pliable bag of the closed system eliminates the air-blood interface, while still being exposed to atmospheric pressure. Volume is measured by weight or by change in radius of the container. The closed reservoir collapses when emptied, as an additional safety feature.

Bubble oxygenators use the reservoir for ventilation. When the reservoir is examined from the exterior, the blood is already oxygen rich and appears bright red. As blood enters the reservoir, gaseous emboli are mixed directly with the blood. Oxygen and carbon dioxide are exchanged across the boundary layer of the blood and gas bubbles. The blood will then pass through a filter that is coated with an antifoam solution, which helps to remove fine bubbles. As blood pools in the reservoir, it has already exchanged carbon dioxide and oxygen. From here, tubing carries the blood to the rest of the heart-lung machine.

In opposition to this technique is the membrane oxygenator. Tubing carries the oxygen-poor blood from the reservoir through the pump to the membrane oxygenator. Oxygen and carbon dioxide cross a membrane that separates the blood from the ventilation gasses. As blood leaves the oxygenator, it is oxygen rich and bright red in color.

When blood is ready to be returned from the heart-lung machine to the patient, the arterial line filter will be encountered. This device is used to filter small air bubbles that may have entered, or been generated by, the heart-lung machine. Following this, filter tubing completes the blood path as it returns the blood to the arterial cannula to enter the body.

Fluid being returned from the left ventricle and surgical suction require filtration before the blood is reintroduced to the heart-lung machine. Blood enters a filtered reservoir, called a cardiotomy, which is connected with tubing to the venous reservoir. Other fluids such as blood products and medications are also added into the cardiotomy for filtration of particulate.

Heat exchangers allow body and organ temperatures to be adjusted. The simplest heat exchange design is a bucket of water. As the blood passes through the tubing placed in the bath, the blood temperature will change. A more sophisticated system separates the blood and water interface with a metallic barrier. As the water temperature is changed, so is the blood temperature, which enters the body or organ circulation, which changes the tissue temperature. Once the tissue temperature reaches the desired level, the water temperature is maintained. Being able to cool the blood helps to preserve the organ and body by metabolizing fewer energy stores.

Because respiration is being controlled, and a machine is meeting metabolic demand, it is necessary to monitor the patient's blood chemical makeup. Chemical sensors placed in the blood path are able to detect the amount of oxygen bound to hemoglobin. Other, more elaborate sensors can constantly trend the blood pH, partial pressure of oxygen and carbon dioxide, and electrolytes. This constant trending can quickly analyze the metabolic demands of the body.

Sensors that communicate system pressures are also a necessity. These transducers are placed in areas where pressure is high, after the pump. Readings outside of normal ranges often alert the operator to obstructions in the blood-flow path. The alert of high pressure must be corrected quickly as the heart-lung machine equipment may disengage under the stress of abnormally elevated pressures. Low-pressure readings can be just as serious, alerting the user to faulty connections or equipment. Constant monitoring and proper alarms help to protect the integrity of the system.

Constant scanning of all components and monitoring devices is required. Normal values can quickly change due to device failure or sudden mechanical constrictions. The diagnosis of a problem and quick troubleshooting techniques will prevent additional complications.

3.9.1.2. Application

·         Coronary artery bypass surgery

·         Cardiac valve repair and/or replacement

·         Repair and/or palliation of congenital heart defects Transplantation

·         Repair of some large aneurysms 

3.9.2. Treadmill Test

Cardiac stress test is test used in medicine and cardiology to measure the heart’s ability to respond to external stress in a controlled clinical environment. The stress response is included by exercise or drug stimulation. Cardiac stress tests compares the coronary circulation while the patient is at rest with the same patient’s circulation observed during maximum physical exertion, showing any abnormal blood flow to the heart’s muscle tissue. The results can be interpreted as a reflection on general physical condition of test patient. This test can be used to diagnose ischemic heart disease, and for patient prognosis after a heart attack.

Working

The cardiac stress test is done with heat stimulation, by exercise on a treadmill with the patient connected to an ECG. The level of mechanical stress is increased by adjusting the difficulty and speed. The test administrator or attending physician examines the symptoms and blood pressure response. With use of ECG the test is called a cardiac stress test.

 

Fig 3.20 Treadmill Test

Function

It has two main functions which are perfusion stress test is appropriate for particular patients especially those with an abnormal resting electrocardiogram. Intracoronary ultrasound or angiogram can provide more information at the risk of complications associated with cardiac catherization. The treadmill test has sensitivity of 73 to 90% and specificity 50 to 74%

Adverse Effects

Side effects from cardiac stress testing may include palpations, chest pain, myocardial infarction, shortness of breath, headache, nausea or fatigue and also adenosine and dipyridamole can cause mild hypotension.

Limitations

The stress test cannot detect Atheroma and vulnerable plaques.

Table 3.8 Technical specifications of Treadmill Test

S.No	Parameter	Specification
1	Machine size	182*77*142(cm)
2	Folded size	91*77*163(cm)
3	Running surface	18*60in
4	Walking surface height	5.5 in.
5	Speed range	0 to 13.2.4 mph at 220 VAC/60 Hz
6	Motor	3.0 HP
7	Weight	181.4 kg
8	Power	200 to 240 VAC, 50/60 Hz, single phase

3.10. Neonatal

Neonatal units specialize in the care of babies born early, with low weight or who have a medical condition that requires specialized treatment. The services combine dedicated medical and nursing care with advanced life-supporting equipment.

3.10.1. Warmer

Infant temperature will vary and this may lead to Hypothermia. Hypothermia is a condition in which core temperature drops below the required temperature for normal metabolism and body functions which is defined as 35.0 °C (95.0 °F). If exposed to cold and the internal mechanisms are unable to replenish the heat that is being lost, a drop in core temperature occurs. To avoid hypothermia Infant warmer is used

Fig 3.21 Infant Warmer

Principle

A heating element generates a significant amount of radiant energy in the far IR wavelength region. The radiant output of the heating unit is also limited to prevent thermal damage to the infant.

Procedure

Infrared light are exposed to the infant, when the temperature difference is detected by the thermistor. To avoid damaging the infant’s retina and cornea are worn with cloth goggles.

Heat exchange between the blood and tissue surfaces occurs

The IR energy is readily absorbed by the infant’s skin; increased blood flow in the skin then transfers heat to the rest of the body by blood convection and tissue conduction.

Fig 3.22 Block Diagram of Warmer

Technical specification

1. Microprocessor based servo controlled unit allow two operation mode, automatic and manual mode.

2. Audio and Visual alarm function for Power failure, temperature deviation, over temperature & Temperature sensor failure.

3. Transparent Side panel.

4. Heater consists of anti-explosion micro crystal quartz infrared radiation tubes, radiation source 800W.

5. A second thermal cut-out function for more safety.

6. Skin temperature sensor failure function to avoid over temperature

7. Power rating is 150 VA

8. Voltage is 100 to 240 VAC

9. Frequency is 48 to 62 Hz

3.10.2. Phototherapy

Phototherapy is the most common treatment for reducing high bilirubin levels that cause jaundice in a newborn.

In the standard form of phototherapy, baby lies in a bassinet or enclosed plastic crib (incubator) and is exposed to a type of fluorescent light that is absorbed by your baby's skin. During this process, the bilirubin in the baby's body is changed into another form that can be more easily excreted in the stool and urine.

A baby with jaundice may need to stay under a phototherapy light for several days. Phototherapy doesn't damage a baby's skin.

·        The baby is undressed so that as much of the skin as possible is exposed to the light.

·        The baby's eyes are covered to protect the nerve layer at the back of the eye (retina) from the bright light.

·        Feeding should continue on a regular schedule. There is no need to stop breast-feeding.

·        The bilirubin level is measured at least once a day.

·        Potential problems that may occur during this standard form of phototherapy include:

·        Skin rash.

·        Damage to the nerve layer at the back of the eye (retina), if the eyes are not properly protected.

·        Dehydration, if the infant does not receive adequate fluids when feeding.

·        Difficulty in maintaining the proper body temperature.

Another type of phototherapy is a fiber-optic blanket or a band. These devices wrap around a baby and can be used at home. Although fiber-optic phototherapy has been shown to reduce bilirubin levels, it takes longer than conventional phototherapy done in a hospital setting. It can be a good alternative for babies with mild jaundice who are otherwise healthy.

Working

It is widely thought that light can be therapeutic for the human skin and soul. Light at the correct wavelength may also be effective against depression and allergies. There is a wide range of products on the market, at prices from a few tens of pounds to a hundred pounds or so, which are presented as universal remedies for dust allergies or hay fever.

Common to all the devices is that they emit intense red light with a wavelength of 660 nm. Some biophysicists claim that light of this wavelength can have a positive effect on the human body and can initiate healing processes. This so-called ‘phototherapy’ is a treatment which is claimed to have an effect against allergic reactions in the body, since it acts against free oxygen radicals and strengthens the immune system, reducing inflammation of the mucous membrane.

Since this treatment does not take the form of a medicine, but rather the form of visible light, there is no risk of side-effects. There has been scientific research showing that this therapy does not work in every case, but success rates as high as 72 % have been reported. Since it may not be possible to obtain these devices under the NHS or under private medical insurance, our thoughts naturally turn to do-it-yourself. For the enclosure we decided to use an old nasal hair trimmer.

Fig 3.23 Block Diagram of Phototherapy

LED Phototherapy Unit Circuit Diagram

Fig 3.24 Circuit Diagram of Phototherapy Unit

In this circuit the inductive voltage pulse is limited by the LED itself, ensuring that the output voltage will automatically match the forward voltage of the LED.  The small number of components, the circuit can be assembled by soldering them together directly or by using a small piece of strip board.

The circuit can operate from a wide range of voltages, and so we can use either an alkaline AA cell or an AA-size NiMH rechargeable cell with a voltage of 1.2 V. The current consumption of the circuit is about 20 mA. Assuming the circuit has been built correctly, the red LED should light brightly as soon as power is applied. Five to ten minutes’ use in each nostril every day should be sufficient to obtain noticeable benefit after two weeks of treatment

3.11. Casualty

Staffed and equipped to provide rapid and varied emergency care, especially for those whoare stricken with sudden and acute illness or who are the victims of severe trauma. The emergency department may use a triage system of screeningand classifying clients to determine priority needs for the most efficient use of available personnel and equipment. Also called emergency room.

3.11.1. C-Arm

A C-arm is a medical imaging device that is based on X-ray technology and can be used flexibly in various ORs within a clinic. The name is derived from the C-shaped arm used to connect the X-ray source and X-ray detector to one another.

Since the introduction of the first C-arm in 1955 the technology has advanced rapidly. Today, mobile imaging systems are an essential part of everyday hospital life: Specialists in fields such as surgery, orthopedics, traumatology, vascular surgery and cardiology use C-arms for intraoperative imaging. The devices provide high-resolution X-ray images in real time, thus allowing the physician to monitor progress at any point during the operation and immediately make any corrections that may be required. Consequently, the treatment results are better and patients recover more quickly. Hospitals benefit from cost savings through fewer follow-up operations and from minimized installation efforts.

Working

 A C-arm comprises a generator (X-ray source) and an image intensifier or flat-panel detector. The C-shaped connecting element allows movementhorizontally, vertically and around the swivel axes, so that X-ray images of the patient can be produced from almost any angle.

The generator emits X-rays that penetrate the patient's body. The image intensifier or detector converts the X-rays into a visible image that is displayed on the C-arm monitor. The doctor can identify and check anatomical details on the image such as blood vessels, bones, kidney stones and the position of implants and instruments at any time.

In the case of analog image intensifiers the X-ray strikes a fluorescent surface after being attenuated to different degrees through the patient's body. Depending on the strength of the radiation it causes the surface to glow more or less brightly. Behind the surface is a vacuum tube, at the end of which an analog camera captures the glow and displays it on the monitor. Due to the curved surface of the tube the accuracy of the image diminishes toward the edges, leading to distortions.

Modern flat-panel technology is the digital development of image intensifier technology. The intensity of the incoming X-rays is converted directly into a digital value. Dispensing with electron optics allows distortion-free images to be produced, hence improving the image quality

3.12. ICU

An intensive care unit (ICU), also known as an intensive therapy unit or intensive treatment unit (ITU) or critical care unit (CCU), is a special department of a hospital or health care facility that provides intensive care medicine.

3.12.1. Ventilator

A ventilator is a machine that supports breathing. These machines mainly are used in hospitals. A medical ventilator can be defined as any machine designed to mechanically move breathable air into and out of the lungs, to provide the mechanism of breathing for a patient who is physically unable to breathe, or breathing insufficiently. The figure 3 shows the ventilator Machine.

Fig 3.25 Ventilator

While modern ventilators are generally thought of as computerized machines, patients can be ventilated indefinitely with a bag valve mask, a simple hand-operated machine. Ventilators are chiefly used in intensive care medicine, home care, and emergency medicine (as standalone units) and in anaesthesia (as a component of an anaesthesia machine).

Principle

Get oxygen into the lungs. Remove carbon dioxide from the body. (Carbon dioxide is a waste gas that can be toxic.) Help people breathe easier. Breathe for people who have lost all ability to breathe on their own. The medicines used to induce anaesthesia can disrupt normal breathing. A ventilator helps make sure that you continue breathing during surgery. A ventilator also may be used during treatment for a serious lung disease or other condition that affects normal breathing.

Need for Ventilation

During surgery if you're under anaesthesia (that is, if you're given medicine that makes you sleep and/or causes a loss of feeling). If a disease or condition impairs your lung function

Method

Ventilators blow air or air with extra oxygen into the airways and then the lungs. The airways are pipes that carry oxygen-rich air to your lungs. They also carry carbon dioxide, a waste gas, out of your lungs. The method of ventilator procedure is shown in the figure 3. and the figure 3. shows the block diagram ventilator machine and the process of ventilation to the patients.

Fig 3.26 Process of Ventilation

Fig 3.27  Block Diagram of Ventilator

The airways include:

·        Nose and linked air passages, called nasal cavities

·        Mouth

·        Larynx or voice box

·        Trachea or windpipe

·        Tubes called bronchial tubes or bronchi, and their branches

Working

1. Inspiratory Phase

During inspiration, ventilators generate tidal volumes by producing gas flow along a pressure gradient. The machine generates either a constant pressure (constant-pressure generators) or constant gas flow rate (constant-flow generators) during inspiration, regardless of changes in lung mechanics. Nonconstant generators produce pressures or gas flow rates that vary during thecycle but remain consistent from breath to breath. For instance, a ventilator that generates a flow pattern resembling a half cycle of a sine wave (e.g., rotary piston ventilator) would be classified as a nonconstant-flow generator. An increase in airway resistance or a decrease in lung compliance would increase peak inspiratory pressure but would not alter the flow rate generated by this type of ventilator

2. Transition Phase from Inspiration to Expiration

Termination of the inspiratory phase can be triggered by a pre-set limit of time (fixed duration), a set inspiratory pressure that must be reached, or a predetermined tidal volume that must be delivered. Time-cycled ventilators allow tidal volume and peak inspiratory pressure to vary depending on lung compliance. Tidal volume is adjusted by setting inspiratory duration and inspiratory flow rate. Pressure-cycled ventilators will not cycle from the inspiratory phase to the expiratory phase until a pre-set pressure is reached. If a large circuit leak decreases peak pressures significantly, a pressure-cycled ventilator may remain in the inspiratory phase indefinitely. On the other hand, a small leak may not markedly decrease tidal volume, because cycling will be delayed until the pressure limit is met.

Volume-cycled ventilators vary inspiratory duration and pressure to deliver a pre-set volume. In reality, modern ventilators overcome the many shortcomings of classic ventilator designs by incorporating secondary cycling parameters or other limiting mechanisms. For example, time-cycled and volume-cycled ventilators usually incorporate a pressure-limiting feature that terminates inspiration when a pre-set, adjustable safety pressure limit is reached. Similarly a volume pre-set control that limits the excursion of the bellows allows a time-cycled ventilator to function somewhat like a volume-cycled ventilator, depending on the selected ventilator rate and inspiratory flow rate

3. Expiratory Phase

The expiratory phase of ventilators normally reduces airway pressure to atmospheric levels or some pre-set value of positive end-expiratory pressure (PEEP). Exhalation is therefore passive. Flow out of the lungs is determined primarily by airway resistance and lung compliance. PEEP is usually createdwith an adjustable spring valve mechanism or pneumatic pressurization of the exhalation (spill) valve

4. Transition Phase from Expiration to Inspiration

Transition into the next inspiratory phase may be based on a pre-set time interval or a change in pressure. The behavior of the ventilator during this phase together with the type of cycling from inspiration to expiration determines ventilator mode.

During controlled ventilation, the most basic mode of all ventilators, the next breath always occurs after a pre-set time interval. Thus tidal volume and rate are fixed in volume-controlled ventilation, whereas peak inspiratory pressure is fixed in pressure-controlled ventilation. Controlled ventilation modes are not designed for spontaneous breathing. In the volume-control mode, the ventilator adjusts gas flow rate and inspiratory time based on the set ventilator rate and I: E ratio. In the pressure-control mode, inspiratory time is also based on the set ventilator rate and inspiratory-to-expiratory (I: E) ratio, but gas flow is adjusted to maintain a constantinspiratory pressure.

Positive End-Expiratory Pressure (PEEP)

Positive end-expiratory pressure (PEEP) is the pressure in the lungs (alveolar pressure) above atmospheric pressure (the pressure outside of the body) that exists at the end of expiration. The two types of PEEP are extrinsic PEEP (PEEP applied by a ventilator) and intrinsic PEEP (PEEP caused by a non-complete exhalation). Pressure that is applied or increased during an inspiration is termed pressure support.

Infections

One of the most serious and common risks of being on a ventilator is pneumonia. The breathing tube that's put in your airway can allow bacteria to enter your lungs. As a result, you may develop ventilator-associated pneumonia (VAP).The breathing tube also makes it hard for you to cough. Coughing helps clear your airways of lung irritants that can cause infections.

3.12.2. Syringe Pump

A syringe pump is a small infusion pump (some include infuse and withdraw capability), used to gradually administer small amounts of fluid (with or without medication) to a patient for using chemical and biomedical research. Syringe pump which I have seen in hospitals is given figure 3.

Fig 3.28 Syringe Pump

Types

Types of syringe pumps are explained below.

·        Infusion Syringe Pump

Infusion pumps are excellent for delivering precise amounts of fluids for many applications, including the injection of calibrant into a mass spectrometer or reaction chamber, extended drug delivery to animals and other general infusions and delivery users.

·        Infusion/withdrawal Syringe pumps

The infuse/withdrawal pumps allow application such as atomic withdrawal of samples and unattended filling of syringes at low flow rates.

·        Push-pull syringe pumps

The push-pull pumps provide simultaneous infusion and withdrawal with opposing syringes on a single drive for application such as continuous pumping.

Purpose

The most popular use of syringe drivers is in palliative care, to continuously administer analgesics (pain killers) and other drugs. This prevents periods during which medication levels in the blood are too high or too low, and avoids the use of multiple tablets (especially in people who have difficulty swallowing). As the medication is administered subcutaneously, the area for administration is practically limitless although edema may interfere with the action of some drugs.

Syringe drives are also useful for delivering (IV) medications over several minutes. In the case of a medication which should be slowly pushed in over the course of several minutes, this device saves staff time and errors.

Syringe Pumps are also useful in micro fluidic application, such as micro reactor design and testing, and also in chemistry for slow incorporation of a fixed volume of fluid into a solution.  In enzyme kinetics syringe drivers can be used to observe rapid kinetics as part of a stopped flow apparatus.

          The technical specification of syringe pump is given in the Table 3.14.

Table 3. Technical specification of syringe pump

S.No	Parameter	Specification
1	Flow rate	0.05-10mL/h in 0.01mL
2	Syringe  size	2mL to 50/60mL
3	Occlusion pressure	100-1500mmHg
4	Battery	li-Polymer 1800mAh
5	Dimension	38 x 55 x 190mm
6	Weight	400 with battery
7	Temperature	+15Cto 45C

3.13. OT

An operating theatre is where certain invasive surgical procedures that is operations that involve cutting into and working inside a patient’s body - take place. This might involve either minimally invasive procedures like keyhole surgery – where cameras and a laparoscope are inserted through small incisions – or open surgery where surgeons make larger cuts to reach the internal organs. Complicated operations can last many hours.

3.13.1. Diathermy

Diathermy  is  used  in  physical  therapy  to  deliver  moderate  heat directly to pathologic lesions in the deeper tissues of the body.

Surgically, the extreme heat that can be produced by diathermy may be used to destroy neoplasm, warts, and infected tissues, and to cauterize blood vessels to prevent excessive bleeding.

The technique is particularly valuable in neurosurgery and surgery of the eye.

The diathermy equipment is displayed in the Fig 3.28

                                                    Fig 3.29 Diathermy

Principle

The surgical diathermy performs its function by the application of high density radio frequency current which can be used to cut or coagulate tissue. Its improper use can result in electrical burns and even electrocution. The principles underlying its safe use are outlined, and detailed recommendations are made to ensure the patient's safety

Procedure

The tissue is heated by an electric current. The latter uses heat conduction from a probe heated to a glowing temperature by a direct current (much in the manner of a soldering iron). This may be accomplished by direct current from dry-cells in a penlight-type device. When this results in destruction of small blood vessels and halting of bleeding, it is technically a process of electro coagulation,

Electro surgery and surgical diathermy involve the use of high frequency A.C. electrical current in surgery as either a cutting modality, or else to cauterize small blood vessels to stop bleeding. This technique induces localized tissue burning and damage, the zone of which is controlled by the frequency and power of the device. Some source insist that electro surgery be applied to surgery accomplished by high frequency A.C. cutting, and that "electrocautery" be used only for the practice of cauterization with heated nichrome wires powered by D.C. current, as in the handheld battery-operated portable cautery tools. The Block Diagram of surgical diathermy equipment is shown in figure 3.29

Fig: 3.30 Block Diagram of Surgical diathermy

 1. Monopolar diathermy

·        Electrical plate is placed on patient and acts as indifferent electrode

·        Current passes between instrument and indifferent electrode

·        As surface area of instrument is an order of magnitude less than that of the plate

·        Localised heating is produced at tip of instrument

·        Minimal heating effect produced at indifferent electrode

2.Bipolar diathermy

Two electrodes are combined in the instrument (e.g. forceps) Current passes between tips and not through patient

Technical Specification of Surgical diathermy

Modes Of Operation                -        Cut, Coagulate And Blend

Operating Voltage                            -        220 V Ac, 50 Hz

Max Power Consumption                 -        275 Watts

Modes                                      -        175 Watts,400 Ohms - Cut

                                                          70Watts,400  Ohms  -  Coag

                                                          400 Ohms – Bipolar

Operating Frequency               -        360 Khz

Alarms                                     -        Audio         Visual Alarms with Output Cutoff for                                                Inactive Cable, Active Cable, Patient Plate

Weight        -        10kgs

Size (Cm)    -        34H×37B×17H

Model         -        ELECTROSURGE        250B Solid State Surgical Diathermy

Application of surgical diathermy

•The  application of a high-frequency electric current to biological tissue as a means to cut, coagulate, desiccate, or fulgurate tissue.

•Surgical devices are frequently used during surgical operations helping to prevent blood loss in hospital operating rooms or in outpatient procedures

•Electrosurgery is commonly used in          dermatological, gynecological, cardiac, plastic, ocular, spine, ENT, maxillofacial,  orthopedic, urological, neuro and general surgical procedures as well as certain dental procedures.

3.13.2. Anesthesia Machine

The anaesthetic machine or anaesthesia machine is used by anaesthesiologists, nurse anaesthetists, and anaesthesiologist assistants to support the administration of anaesthesia. The most common type of anaesthetic machine in use to continuous-flow anaesthetic machine, which is designed to provide an accurate and continuous supply of medical gases (such as oxygen and nitrous oxide), mixed with an accurate concentration of anaesthetic vapour (such as isoflurane), and deliver this to the patient at a safe pressure and flow. The figure 3.11 shows the Anaesthesia Machine Model.

Fig 3.31 Anasthesia machine

Principle

The anaesthetic machine dispenses the gases that are necessary to induce sleep and prevent pain to patients during surgical procedures or other potentially painful manipulations.

The basic anesthetic delivery system consists of a source of oxygen (O2), an O2 flowmeter, a precision vaporizer, which produces a vapor from a volatile liquid anesthetic, a patient breathing circuit (tubing, connectors and valves), and a scavenging device that removes any excess anesthetic gases.

          During delivery of gas anaesthesia to the patient, O2 flows through the vaporizer and picks up the anesthetic vapors. The O2-anesthetic mix then flows  through  the breathing  circuit  and  into  the patient's  lungs,  usually by spontaneous  ventilation  (respiration).  Occasionally,  it  is  necessary  to  use assisted ventilation, especially when opening   the chest (thoracic) cavity. Assisted ventilation is accomplished by use of a ventilator or respirator. The Block Diagram of Anesthesia machine are shown in the figure 3.31

Fig: 3.32 Block Diagram of Anesthesia machine

Oxygen Flowmeter

This device uses an adjustable needle valve to deliver the desired flow in ml or litters per minute to the patient circuit. Flows of around 0.5-2 litres of O2      per minute are commonly used  with   rodent anaesthesia         machines. Flowmeters are individually calibrated for a specific gas.

Patient Breathing Circuit

The  patient  breathing  circuit  is  the  highway  for  anesthetic  gas delivery to the patient. The goals of an anesthetic breathing circuit are to:

A. Deliver oxygen to the patient

B. Deliver anesthetic to the patient

C. Remove carbon dioxide that is produced by the patient

D. Provide a method for assisting or controlling ventilation, if needed

Technical Specification

Height                            -        135.8 cm/53.4 in

Weight                            -        Approximately 136 kg/300 lb

Casters

1.  Diameter                             -        12.5 cm/5 in

2.  Brakes                       -        Single foot lever locks and unlocks two front casters

Tidal volume range        -        20 to 1500 mL (Volume Control and SIMV)

5 to 1500mL (Pressure Control Mode)

Pressure (PInspired) range -    5 to 60 cm H2O (increments of 1 cm H2O)

 Power input                           -        120 Vac, 60 Hz, 10A

Battery type                             -        Internal rechargeable sealed lead acid

Ventilator monitoring

1.  O2 %                         -        5 to 110%

2.  Peak pressure            -        –20 to 120 cm H2O

3.  Mean pressure           -        –20 to 120

 cm H2O

4.  PEEP delivery           -        ±1.5 cm H2O

5.  Volume monitoring - > 210 mL = better than 9%

< 210 mL = better than 18 mL

< 60 mL = better than 10 mL

6.  Pressure monitoring -         ±5% or ±2 cm H2O

Application

•        A medical anesthesia machine is designed to deliver drugs that help to eliminate pain and other unwanted sensations.

•        The continuous flow anesthetic machine provides an accurate and constant supply of medical gases (such as air, oxygen and nitrous    oxide), mixed with an accurate concentration of anesthetic vapor (such as isoflurane), and delivers this mixture to the patient at a desired pressure and flow.

CHAPTER 4

CONCLUSION

An extensive study is done by understanding the working principle method of operation power utility and cost effectiveness. A good practical exposure for the upcoming medical field is governed by this hospital training by having a well interaction with the hospital training session has been a good learning for us as we would implement our knowledge for future practices.

The importance of the biomedical department in a Hospital is also realized. The utilization of equipment and maintenance of equipment are all understandable practically. The hospital training determines the entirely practical knowledge that is necessary for a biomedical engineer.

Thus the Hospital training gave us a good knowledge about the equipment and abnormal problems rectified in the equipment. The hospital training was helpful to gain technical knowledge as Biomedical Engineering students.

REFERENCES

1.  Arumugam, M ―Biomedical Instrumentation‖ 2009, Anuradha Publication, Thirteenth Reprint.

2. Joseph J.Carr, John M. Brown., Introduction to Biomedical Equipment Technology‖ 2009, Pearson Education.Inc Fourth Edition.

3. R S Khandpur., Handbook of Biomedical Instrumentation‖ 2009, Tata McGraw Hill Publisher, Fourteenth Reprint.

4. Leslie Cromwell, Fred J. Weibell, Erich A. Pfeiffer., ―Biomedical Instrumentation and Measurements‖, Pearson Education.Inc, Second Edition.