How Does Life Support Work?

Mechanical Respiration

Life support is a medical term for a series of therapies performed on a severely injured or ill patient whose body would be otherwise unable to perform the basic functions required to live, such as filter their own blood of natural toxins, breath, and absorb nutrients through their gastrointestinal system. These are done in addition to such standard practices as catheterizing a patient and establishing an intravenous drip through which drugs may be administered. One of the most immediately important of these practices is mechanical respiration. Essentially, a tube is passed down the trachea via the mouth all the way to the bronchial tubes which are the precursors to the lungs. A mechanical respirator is connected to the other end of the tube. This respirator periodically increases the air pressure down the length of the tube, forcing air into the lungs. This is the inhale portion. To exhale, the pressure is cut to zero, during which time the natural elastic recoil of the chest cause the lungs to exhale. This is repeated for hours, if not days, until the patient is capable of breathing on his own.

Total Parenteral Nutrition

Total Parenteral Nutrition is a procedure used when the body is incapable, due to illness or injury, of absorbing nutrients through the intestinal lining. A large bore hole is opened in the subclavian artery or jugular vein, into which an intravenous catheter is placed. Essentially, it's a port in the vein. A medical infusion pump is connected to the port, which leads to a bag of sterile nutrient solution containing all the minerals and vitamins the body needs.
The pump slowly forces the solution into the artery, to be absorbed throughout the bloodstream at a rate of 1 to 10 mm per hour. These pumps usually increase the rate of infusion three times a day to simulate normal mealtimes to help the body better metabolize the nutrients.

Dialysis

Dialysis is designed to artificially simulate the normal daily functions of the kidneys. The kidneys perform two important functions. They filter out the fixed hydrogen ions which are a form of waste that the body produces naturally through normal metabolic function. They also maintain the equilibrium between the body's water and minerals. Two large bore needles are inserted into the veins of the patient's arm. These needles are connected to a dialysis machine. At a steady rate, blood is drawn into the machine through one of the needles, where it passes through a number of semi-permeable material layers which filter out the hydrogen ions and excess mineral content. The blood then goes down the other needle back into the patient. For a patient whose kidneys have failed as a result of sudden trauma to the body, dialysis must be performed an average of 4 hours a day to ensure that the body's waste does not reach toxic levels.