Non-invasive ventilation in the weaning process.

Patients with chronic airflow obstruction and difficulty in weaning from mechanical ventilation are at increased risk for intubation-associated complications and mortality because of prolonged invasive mechanical ventilation. Non-invasive ventilation (NIV) may avert most of the pathophysiologic mechanisms associated with weaning failure in these patients. Several randomised controlled trials have shown that the use of NIV in order to advance extubation in difficult patients can result in reduced periods of endotracheal intubation, complication rates and survival. The published data with the outcome as a primary variable are nearly exclusively from patients who had pre-existing lung disease. In addition, the patients were hemodynamically stable, with a normal level of consciousness, no fever and a preserved cough reflex. The use of NIV in the management of respiratory failure after extubation did not show clinical benefits, although clinical trials included a small proportion of chronic respiratory patients. In contrast, NIV immediately after extubation is effective in avoiding respiratory failure after extubation in patients at risk for this complication, particularly those with chronic respiratory disorders and hypercapnic respiratory failure.