Physiologic responses to long-term ventilation.

Abstract

Long-term MV, delivered by way of a tracheostomy or noninvasive mask, often is indicated in patients with restrictive or neuromuscular pulmonary diseases and occasionally in patients with severe obstructive hypercapnic respiratory failure. Regardless of the mode of ventilation, respiratory physiology seems to be significantly impacted in these patients. Although the effects of ventilation can be unpredictable, they often seem to be favorable. Selected patients can develop increased sensitivity to hypercapnia, with subsequent improvements in blood gas tensions and decreased pulmonary artery pressures, which result in augmented cardiac function and greater tolerance to exercise. The patient-ventilator interaction, mode of ventilation, and degree of support should be considered when managing these patients. For some patients, particularly patients with fibrotic lung disease or COPD, chronic MV likely does not alter pathophysiology or improve prognosis.