Mechanical ventilation in critically ill patients

Patients who inhabit the ICU, whether medical or surgical, frequently require mechanical ventilatory support. Therefore, a basic knowledge of conventional as well as the more recently described 'alternative' modes of ventilation is an important requirement for any physician involved in the care of critically ill patients. The anaesthetist, particularly in light of the recent emphasis on becoming a 'complete perioperative physician', certainly requires this knowledge in addition to an understanding of the indications, objectives, and complications of mechanical ventilation. Various important principles of cardiopulmonary physiology are outlined in relation to the effects of applied positive pressure, allowing the clinician a further sophistication in the care of mechanically ventilated critically ill patients. Critically ill patients, unlike healthy operative patients, require a period of weaning from ventilatory support, so a familiarity with the various modes of weaning and the principles behind them will benefit the clinician in the care of these patients.