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Definition
Life support refers to a spectrum of techniques used to maintain life after the failure of one or more vital organs.
Description
Successful life support begins with establishing the ABC's of resuscitation—airway, breathing, and circulation.
The airway refers to a clear passageway for air to enter the lungs from outside the body. The patient's airway may become blocked by:
- foreign body obstruction, as by food or dentures
- injury-related damage and swelling, as from a wound or surgery
- loss of protective reflexes due to coma of any origin
Life support may begin with basic cardiopulmonary resuscitation (CPR), as in cases of cardiac arrest. Thereafter, the most common technique used to create a secure airway is insertion of an endotracheal (ET) tube through the mouth or nose into the windpipe (trachea). An alternative method of securing an airway is by tracheotomy, a surgical procedure in which a tube is inserted into the trachea through an incision made in the base of the throat. Of the two options, placement of an ET tube is usually quicker and more convenient, and thus occurs much more commonly. Doctors perform a tracheotomy when they cannot establish an ET airway, or when the patient will require an artificial airway for more than a week or two.
Breathing refers to the movement of air in and out of the lungs. Inadequate breathing may result from:
- heart disease, as in congestive heart failure
- primary disease of the lungs, such as pneumonia, asthma, or emphysema
- coma of any cause, such as narcotic overdose or stroke
- muscle fatigue or neuromuscular disease (spinal cord injury or polio)
- pain, from rib fractures or surgery on the chest
When the patient cannot breathe sufficiently, the physician will use a ventilator, a machine that pumps air in and out of the patient's lungs. For many doctors and members of the public, the term "life support" calls up the image of an ET tube and ventilator.
Circulation refers to the flow of blood around the body from the heart to vital organs. Circulation can fail due to:
- primary disease of the heart (heart attack)
- blood loss (trauma or internal bleeding of any cause)
- severe infection (sepsis)
- drug reactions or overdoses
- extreme allergic reaction
- severe dehydration (gastroenteritis or heat-related illness)
In order to ensure adequate circulation, the patient will require one or more intravenous (IV) tubes (catheters). The IVs may include both the short needle and tube commonly used in the hand or forearm, and longer catheters inserted into the larger and more central veins of the body. Catheters inserted into these larger veins are known as central lines. Through the IVs the patient receives fluids, drugs, and blood transfusions as needed to support the circulation.
Once the ABC's are secure, life support is directed at maintaining homeostasis, the body's delicate chemical and physical balance. In a healthy person, the body keeps precise control over many components of its makeup, such as its fluids, nutrients, and pressures. When vital organs fail, the body can no longer regulate these components, and the doctor must take steps to restore the normal state.
Preserving the body's internal equilibrium requires careful monitoring of innumerable indicators of the patient's well-being. These indicators include:
- vital signs (heartbeats per minute, breaths per minute, blood pressure, body temperature, and weight)
- fluids (input and output of the body)
- blood cell counts
- chemical substances of the body (sodium, potassium, sugar, and many others)
- pressures in the circulation, lungs, and perhaps even the brain
- presence of germs (bacteria, fungi) causing infection in body systems (lungs, blood, urine)
This intensive monitoring usually takes place in an intensive care unit (ICU) or critical care unit (CCU) and requires:
- specialized physicians, such as cardiologists, intensivists, and surgeons
- highly-skilled nursing care, often one nurse per patient around-the-clock
- extensive support staff, such as respiratory therapists, laboratory technicians, radiology technicians, dieticians, and pharmacists
- constant measurement of basics such as pulse, heart rhythm, and oxygen level in the blood
- frequent inspection of the patient's alertness, color, and level of pain
- use of catheters in the veins and arteries to withdraw blood samples and measure pressures in the circulation
- use of tubes in the bladder (Foley catheter), stomach (nasogastric tube), and other body cavities
- frequent laboratory tests on blood, urine, drainage from wounds, and other body specimens
- x-ray, ultrasound, computerized tomography (CT), and other imaging procedures
- electrocardiograms
The treatments of life support include:
- oxygen
- intravenous fluids with sugar and basic salts
- drugs to improve circulation and other body functions
- antibiotics
- transfusions
- surgery
- nutritional supplements by vein or stomach tube
- tubes in body cavities (chest or abdomen) to relieve fluid buildup
- dialysis
- pacemaker
- electrical defibrillation
- various machines to assist heart or lung function
- transplantation of organs or mechanical substitutes (artificial heart)
- sedation or even temporary paralysis to enable the patient to tolerate these procedures
— Isaac R. Berniker
