In medicine, mechanical ventilation is a method to assist or replace spontaneous breathing. Mechanical ventilation can be life-saving and is a mainstay of CPR, intensive care medicine, and anesthesia. Mechanical ventilation is used when natural (spontaneous) breathing is absent (apnea) or insufficient. This may be the case in cases of intoxication, cardiac arrest, neurological disease or head trauma, paralysis of the breathing muscles due to spinal cord injury, or the effect of anesthetic or muscle relaxant drugs. Various pulmonary diseases or chest trauma, cardiac disease, sepsis, and shock may also necessitate ventilation.
Depending on the situation, mechanical ventilation may be continued for a few minutes or many years. While returning to spontaneous breathing is rarely a problem in routine anesthesia, weaning an intensive care patient from prolonged mechanical ventilation can take weeks or even months. Some patients never adequately regain the ability to breathe and require permanent mechanical ventilation. This is often the case with severe brain injury, spinal cord injury, or neurological disease.