Medical Tests, Procedures, and Equipment: A Comprehensive Look

Posted on Jan 31, 2025 in Marketing and Commercial Management

Blood Tests

Tests on Blood Cells:

  • Red blood cells (RBC) – 4.5-5.5 million
  • White blood cells (WBC) – 6,000-10,000
  • Blood platelets – 200,000-800,000

Centrifugal Method

By spinning blood in a centrifuge, the blood cells can be sedimented at the bottom of the test tube. Most of this column consists of the red blood cells, with the other cells forming a thin, buffy layer on top of the red cells. The volume of the packed red cells is expressed as a percentage of the total blood volume.

Conductivity (Coulter) Method

It makes use of the fact that blood cells have a much lower electrical conductivity than the solution in which they are suspended. It consists of a beaker with diluted blood. The negative pressure generated by the pump causes a flow of the solution from the beaker through the orifice into the glass tube. Each time a blood cell is swept through the orifice, it temporarily blocks part of the electrical current path.

Chemical Tests on Blood

  1. Colorimeter or Filter-photometer method
  2. Chloridemeter
  3. Spectrophotometer
  4. Autoanalyzer

Colorimeter or Filter-photometer Method

This method is used for measuring transmittance and absorbance of solutions. A filter F selects a suitable wavelength range from the light of a lamp. This light falls on two photoelectric (selenium) cells: a reference cell CR and a sample cell CS.

Flame Photometer

For the measurement of sodium and potassium, however, a different property is utilized. It utilizes the color of the flame to measure the concentration. A flame appears yellow (sodium) or violet (potassium) when their solutions are aspirated into the flame.

Chloridemeter

For the determination of chlorides, a special instrument (chloridimeter) is sometimes used that is based on an electrochemical method. For this test, the chloride is converted into silver chloride with the help of an electrode made of silver wire.

Spectrophotometer

In this device, the filter of the colorimeter is replaced by a monochromator. A monochromator uses a diffraction grating G (or a prism) to disperse light from a lamp that falls through an entrance slit S1, into its spectral components.

Autoanalyzer

The mixing, reaction, and colorimetric determination take place, not in an individual test tube for each sample but sequentially in a continuous stream. The sampler feeds the samples into the analyzer in time sequence. A proportioning pump is used to meter the sample and the reagent. Mixing is achieved by injecting air bubbles. The mixture is incubated while flowing through heated coils.

Physiological Effects of Electrical Current

Electrical accidents are caused by the interaction of electric current with the tissues of the body. For an accident to occur, current of sufficient magnitude must flow through the body of the victim in such a way that it impairs the functioning of vital organs.

The physiological effects of the current depend on:

  • Magnitude of current
  • Current pathway through the body
  • Location of application of shock

The current sensitivity of the heart is much higher. The effect of current applied directly to the heart is often referred to as microshock, while in the effect of current applied through the surface is called macroshock.

Basically, electric current can affect the tissue in two different ways:

First effect: The electrical energy dissipated in the tissue resistance can cause a temperature increase. If a high enough temperature is reached, tissue damage (burns) can occur.

Second effect: An external electric current of sufficient magnitude can cause local voltages that can trigger action potentials and stimulate nerves. When sensory nerves are stimulated in this way, the electric current causes a “tingling” or “prickling” sensation, which at sufficient intensity becomes unpleasant and even painful.

Methods of Electric Shock Accident Prevention
  1. Grounding
  2. Double Insulation
  3. Protection by Low Voltage
  4. Ground-Fault Circuit Interrupter
  5. Isolated Power Distribution Systems

Telemedicine

Telemedicine is the application of telecommunications and computer technology to deliver health care from one location to another. In other words, telemedicine involves the use of modern information technology to deliver timely health services to those in need by the electronic transmission of the necessary information.

Telemedicine Applications

The main applications of telemedicine are found in radiology, pathology, cardiology, and medical education.

Essential Parameters for Telemedicine

  • Primary Patient Data
  • Patient History
  • Clinical information
  • Investigations
  • Data and Reports

Types of Ventilators

Anesthesia Ventilators

These are generally small and simple equipment used to give regular assisted breathing during an operation.

Intensive Care Ventilators

Intensive care ventilators are more complicated, give accurate control over a wider range of parameters.

Ventilators

  • Mechanism of respiration: It is the process of supplying oxygen to tissues and removing carbon dioxide from the tissues.
  • These gases are carried in blood, oxygen from lungs to the tissues and carbon dioxide from the tissues to the lung.
  • Respiration process:
    • Inspiration – breathing in (air to lungs)
    • Expiration – breathing out (air out from lungs)
  • Inspiration results from contraction of the diaphragm whereas expiration results from their relaxation.

Heart-Lung Machine

  • During open-heart surgery, the heart cannot maintain the circulation.
  • It is then necessary to provide extracorporeal (outside the body) circulation with a special machine called a heart-lung machine.
  • A Heart-Lung Machine is a blood pumping machine that takes over the functions of the heart and lungs during surgery (i.e. open-heart surgery).
Functions of a Heart-Lung Machine
  • RESPIRATION: Within which it includes Ventilation and Oxygenation.
  • CIRCULATION: Maintaining circulation at appropriate pressures and flow rates.
  • TEMPERATURE REGULATION: It involves controlled hypothermia.

Hemodialysis

  • The main function of the kidney is to form urine out of blood plasma, which basically consists of two processes:
    1. The removal of waste products from blood plasma
    2. The regulation of the composition of blood plasma
  • Kidney performs these functions through a process involving filtration, reabsorption, excretion.

Lithotripsy

  • Kidney stones are small masses of salts and minerals that form inside the kidneys and may travel down the urinary tract.
  • Kidney stones range in size from just a speck to as large as a ping pong ball.
  • Signs and symptoms of kidney stones include blood in the urine, and pain in the abdomen, groin, or flank.
  • The kidney stones are disintegrated so that they will be removed from the body in the form of small particles without any discomfort.
  • There are mainly two methods:
    • Percutaneous Lithotripsy
    • Extracorporeal shock wave lithotripsy

Infant Incubator

  • An infant incubator is a biomedical device which provides warmth, humidity, and O2 all in a controlled environment as required by the newborn.
  • The temperature is maintained within a specific temperature range, O2 requirements are minimized.
  • In premature newborns susceptible to respiratory problems, because lungs may be unable to supply enough O2 to meet demands.

Fluoroscopy

  • The primary function of a fluoroscope is to perform dynamic studies; that is, the fluoroscope is used to visualize the motion of internal structures and fluids.
  • The purpose of this technique is to get real-time and moving images of the insides of a person by way of the fluoroscope.
  • If something is observed that the radiologist would like to preserve for later study, a radiograph can be made with little interruption of fluoroscopic examination. Such radiograph is known as spot film.

Angiography

  • Angiography is a type of X-ray used to check the blood vessels.
  • Blood vessels don’t show up clearly on a normal X-ray, so a special dye needs to be injected into your blood first.
  • This highlights your blood vessels, allowing your doctor to spot any problems.
  • The X-ray images created during angiography are called “angiograms”.
  • Angiography is carried out in a hospital X-ray or radiology department.

Endoscopy

  • Endoscopy is the insertion of a long, thin tube directly into the body to observe an internal organ or tissue in detail.
  • It can also be used to carry out other tasks including imaging and minor surgery.
  • Endoscopes are minimally invasive and can be inserted into the openings of the body such as the mouth or anus.
  • Alternatively, they can be inserted into small incisions, for instance, in the knee or abdomen. Surgery completed through a small incision and assisted with special instruments, such as the endoscope, is called keyhole surgery.
  • Because modern endoscopy has relatively few risks, delivers detailed images, and is quick to carry out, it has proven incredibly useful in many areas of medicine.
  • Today, tens of millions of endoscopies are carried out each year.

Diathermy

  • High-frequency currents, apart from their usefulness for therapeutic applications, can also be used in operating rooms for surgical purposes involving cutting and coagulation.
  • The frequency of currents used in surgical diathermy units is in the range of 1-3 MHz in contrast with much higher frequencies employed in short-wave therapeutic diathermy machines.
  • This frequency is quite high in comparison with that of the 50Hz mains supply.
  • This is necessary to avoid the intense muscle activity and the electrocution.

Computed Tomography

  • There are two main limitations of using conventional X-rays to examine internal structures of the body.
  • Firstly, the superimposition of the 3-dimensional information onto a single plane makes diagnosis confusing and often difficult.
  • Secondly, the photographic film usually used for making radiographs has a limited dynamic range and, therefore, only objects that have large variations in X-ray absorption relative to their surroundings will cause sufficient contrast differences on the film to be distinguished by the eyes.
  • In computed tomography (CT), the picture is made by viewing the patient via X-ray imaging from numerous angles, by mathematically reconstructing the detailed structures and displaying the reconstructed image on a video monitor.
  • Computed tomography enabled radiologists to distinguish, for the first time, between different types of brain tissue.

Magnetic Resonance Imaging and Nuclear Medicine System

  • Clinical magnetic resonance imaging (clinical MRI) is an imaging technique used in radiology to form pictures of the anatomy and the physiological processes of the body in both health and disease.
  • MRI scanners use strong magnetic fields, radio waves, and field gradients to generate images of the organs in the body.
  • MRI does not involve x-rays, which distinguishes it from computed tomography (CT or CAT).
  • While the hazards of x-rays are now well-controlled in most medical contexts, MRI still may be seen as superior to CT in this regard.
  • MRI is widely used in hospitals and clinics for medical diagnosis, staging of disease and follow-up without exposing the body to ionizing radiation.
  • MRI often may yield different diagnostic information compared with CT. There may be risks and discomfort associated with MRI scans.