Life Support Systems and Life-Extending Technologies

The Intensive Care Unit

The intensive care unit (ICU) is a highly specialized life-support environment coordinating the provision of constant monitoring and support of vital body functions. The purpose of ICU units is to “resuscitate” and maintain critically ill patients alive, not to cure the underlying disease. Even if organized efforts to resuscitate and ventilate people date from 1769 with the Society of Resuscitation of Drowned Persons, in England, the conception of the ICU as a life support environment was not realized until 1953 in Copenhagen. Regular life support technologies in the ICUs and emergency units are defibrillation for cardiopulmonary resuscitation (CPR), mechanical ventilation, heart/lung bypass, dialysis, intravenous drips, vasopressures (e.g., adrenaline) and antibiotics, bodily temperature control, and intubation for total parenteral and enteral hydration and nutrition.

CPR consists in the restoration of breathing and heart function. CPR as first aid is a simple “mouth-to-mouth respiration” technique to supply air to the lungs, and rhythmic chest compressions to maintain circulation and the oxygen supply to the brain and other vital organs until more advanced life support such as defibrillation can be provided. In defibrillation a low electrical shock is delivered to the heart with an automated external defibrillator until the normal sinus rhythm of the heart is restored. Advanced cardiopulmonary resuscitation in addition to defibrillation includes mechanical ventilation (assisted breathing), anti-arrhythmic drugs, vasopressures (drugs to stimulate circulation such as adrenaline) and postresuscitation care.

Mechanical ventilation—that is, the substitution of respiratory function by a ventilator, an external device pumping air and oxygen in and out of the lung—provides the most emblematic image of life support. A first breakthrough in assisted ventilation was the iron lung—an airtight coffin-like box that enclosed the body of the patient keeping the head outside and rhythmically pressured and [Page 659]de-pressured the chest forcing air into the nose and lungs. The iron lung was devised to rescue victims of the polio epidemic of 1920s (poliomyelitis was a viral infection that destroyed nerve substance and led to temporary or permanent paralysis—including respiratory paralysis and ultimately death).

Another major turn took place during the next polio epidemic in 1952, when Danish anesthesiologist Bjorn Ibsen discovered the principle of the modern ventilator as a better alternative to the iron lung. The air was to be supplied via intubation: a tube (endotracheal tube) placed in the airway passage (mouth or nose) or directly into the trachea through a small surgical incision.

Pacemakers, Implantable Cardioverter-Defibrillators, Left Ventricular Assist Devices, Artificial Hearts

Pacemakers and implantable cardioverter defibrillators (implantable medical devices developed to correct cardiac rhythm disturbances) and ventricular assist devices are mechanical blood pumps that replace part or the entirety of the heart's function and are utilized to bridge heart function during heart transplants. The total artificial heart is an implantable mechanical device still under development but being used to alleviate and increase the short-term survival of patients with end-stage heart failure (e.g., patients waiting for a heart transplant).

...