Use of non-invasive ventilation as a weaning technique

In the majority of cases withdrawal of mechanical ventilation and extubation are possible immediately after resolution of the underlying problems responsible for acute respiratory failure (ARF). However there is a group of ventilated patients who require more gradual and longer withdrawal of mechanical ventilation. Non-invasive ventilation (NIV) is theoretically able to counteract several physiological mechanisms associated with weaning failure or difficulties. In fact, following some uncontrolled clinical studies in which NIV was used as a bridge to weaning, several randomized controlled trials showed that the likelihood of weaning success is increased, while the duration of invasive mechanical ventilation and intensive care unit (ICU) stay is decreased, when NIV is used as a weaning technique. Further studies are clearly needed to assess the benefits of NIV in weaning in other forms of respiratory failure, such as acute respiratory distress syndrome, post-surgical complications or cardiac impairment. Despite the fact that two physiological, uncontrolled studies suggested that NIV is feasible as a weaning technique in non-COPD patients, a cautious approach is advisable in such patients, who should be closely monitored to avoid excessive delay in re-intubation, if needed. Post-extubation failure is a major clinical problem in the ICU. A few studies have evaluated the use of NIV as a means to prevent, rather than treat, post-extubation respiratory failure. Two randomized trials were recently performed to assess whether NIV is effective in preventing the occurrence of post-extubation failure in patients at risk. Both studies, which adopted similar criteria to define patients at risk and had comparable study designs, showed that the groups treated with NIV had a lower rate of re-intubation than did the groups in which standard therapy was used; furthermore, in one of the two studies ICU mortality was also reduced in the subgroup of hypercapnic patients treated with NIV.