Ventilatory support in the ICU

The requirement for ventilatory support using positive pressure ventilation to correct the blood-gas abnormalities associated with acute respiratory failure is the most common indication for ICU admission. Ventilatory support may also be indicated in the management of circulatory shock and raised intracranial pressure. Non-invasive ventilation describes the application of positive pressure ventilation with a face mask, avoiding the complications of tracheal intubation associated with conventional ventilatory support. The modern ICU ventilator provides a wide range of modes, although there is no evidence that any particular mode is associated with an improved outcome. Ventilator-induced lung injury is minimized by preventing lung over-distension with the use of appropriate tidal volumes and limiting plateau airway pressure to less than 30 cm H2O. Prolonged ventilatory support is associated with a number of complications and readiness for discontinuation should be assessed on a daily basis. In a significant minority of patients, weaning ventilatory support proves to be a challenge and may reflect underlying chronic respiratory disease, left ventricular impairment or critical illness polyneuropathy/myopathy.