life support (redirected from Artificial life support)

Life Support 

Definition

Life support refers to a spectrum of techniques used to maintain life after the failure of one or more vital organs.

Purpose

A patient requires life support when one or more vital organs fail, due to causes such as trauma, infection, cancer, heart attack, or chronic disease. Among the purposes of life support are to:

• Establish and maintain the ABC's of resuscitation—airway, breathing, and circulation.
• Restore the patient's homeostasis—the internal chemical and physical balance of the body.
• Protect the patient from complications of the underlying disease and its treatment.

Precautions

Patients and families need to recognize that life support is an extremely painful, expensive, and emotionally wrenching experience. Life support exposes a patient to vast risks of further medical complications, and offers no guarantee of a positive outcome. Even in successful cases, recovery may be slow and frustrating.

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

Preparation

The need for life support may arise suddenly and with little warning. All people should discuss in advance with family and doctor their wishes for the use of life support should a medical crisis develop. The doctor will note the preferences in the patient's record. Patients should sign documents such as an Advance Directive and Durable Power of Attorney for Health Care to express their wishes and designate a surrogate decision-maker in case of incapacitation.

Physicians and medical care providers must anticipate the possibility that a patient will require life support, perhaps suddenly. In preparation, doctors and medical staff must:

• Receive training in resuscitation skills
• Monitor patients carefully
• Maintain proper supplies and equipment
• Discuss in advance with patients and patients' families whether or not to begin life support

Aftercare

If a patient survives life support treatments, doctors will cautiously try to wean the patient from the support systems. Being able to breathe adequately without the ventilator is one major hurdle. Patients commonly fail in their first attempts to breathe on their own, often tiring out after a few hours. Thus, the doctor will reconnect the ventilator, give the patient a rest, and try again in a day or two.

As the patient regains organ function, there is less need for monitors, tests, and treatments that require an intensive care setting. The doctor may transfer the patient to a lower level of hospital care, a skilled nursing facility (SNF), or perhaps directly to home. Physical and occupational therapists may help the patient improve strength and endurance. The patient will receive continuing care from the primary doctor and specialists as needed. The patient may require prescription drugs, assist devices, and psychological therapists.

Risks

The risks and consequences of life support are enormous. These risks include:

• Physical dangers
• Emotional suffering
• Financial costs
• Societal discord

The physical dangers of life support encompass all the hazards of the patient's underlying disease and treatments. Among these risks are:

• Permanent damage to the brain, kidneys, and other vital organs caused by poor circulation or low oxygen content of the blood
• Direct damage to organs from use of medical instruments and procedures
• Infections, often with organisms that are highly resistant to antibiotics
• Abnormal blood clots
• Skin ulcers from lying immobilized for long periods
• Extreme pain
• Exposure of medical personnel to communicable diseases

The emotional consequences of life support touch patients, families, and medical caregivers. These repercussions arise from:

• The frightening environment of an ICU
• The need to make life-and-death decisions
• The anger, guilt, and grief that relate to life-threatening illness
• The fact that many lengthy and difficult treatments will end in failure

The financial costs of life support are huge. A single day of life support costs many thousands of dollars. These expenses fall on individual payers, insurance companies, health plans, and governments. All such payers face difficult decisions regarding the allotment of money for such treatment, especially in cases that are likely to be futile.

Society as a whole faces difficult decisions surrounding life support. Some governments have enacted regulations that establish priorities for the spending of health care resources. Patients who do not receive treatment under such rules may feel victimized by society's choices.

Key terms

Cardiopulmonary — Relating to the heart and lungs.

Central line — A tube placed by needle into a large, central vein of the body.

Coma — Unconsciousness.

Defibrillation — Use of an electric shock to restore a normal heartbeat.

Endotracheal tube — A tube placed into the wind-pipe through the nose or mouth.

Foley catheter — A tube that drains urine from the bladder.

Homeostasis — The internal chemical and physical balance of the body.

Nasogastric tube — A tube placed through the nose into the stomach.

Neuromuscular — Relating to nerves and muscles.

Resuscitation — Treatments to restore an adequate airway, breathing, and circulation.

Sepsis — An overwhelming infection with effects throughout the body.

Tracheotomy — A surgical procedure in which a tube is inserted into the trachea through an incision made in the base of the throat.

Trauma — Serious physical injury.

Ventilator — A machine that pumps air in and out of the lungs.

Vital signs — Basic indicators of body function, usually meaning heartbeats per minute, breaths per minute, blood pressure, body temperature, and weight.

Resources

Books

Irwin, Richard S., Frank B. Cerra, and James M. Rippe, editors. Irwin and Rippe's Intensive Care Medicine. Philadelphia: Lippincott-Raven, 1999.

Luce, John M., "Approach to the Patient In a Critical Care Setting." In Textbook of Medicine, edited by Lee Goldman and J. Claude Bennett, 21st ed. Vol. 1. Philadelphia: W.B. Saunders Company, 2000, pp. 483-4.

Tintinalli, Judith E., et al, editors. Emergency Medicine: a comprehensive study guide. New York: McGraw-Hill, 2000.

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life support

n.

A life-support system.

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life support

Etymology: AS, lif, life; L, supportare, to bring up to

the use of any therapeutic technique, device, or technology to maintain physical life functions.