Non-invasive ventilation after surgery

After surgery, hypoxemia and/or acute respiratory failure (ARF) mainly develop following abdominal and/or thoracic surgery. Anesthesia, postoperative pain and surgery will induce respiratory modifications: hypoxemia, pulmonary volumes decrease and atelectasis associated to a restrictif syndrome and a diaphragm dysfunction. Maintenance of adequate oxygenation in the postoperative period is of major importance, especially when pulmonary complications such as ARF occur. Although invasive endotracheal mechanical ventilation has remained the cornerstone of ventilatory strategy for many years for severe acute respiratory failure, several studies have shown that mortality associated with pulmonary disease is largely related to complications of postoperative reintubation and mechanical ventilation. Therefore, major objectives for anesthesiologists and surgeons are first to prevent the occurrence of postoperative complications and second if ARF occurs is to ensure oxygen administration and carbon dioxide CO2 removal while avoiding intubation. Non-invasive ventilation (NIV) does not require endotracheal tube or tracheotomy and its use is well established to prevent ARF occurrence (prophylactic treatment) or to treat ARF to avoid reintubation (curative treatment). Studies shows that patient-related risk factors, such as chronic obstructive pulmonary disease (COPD), age older than 60 years, American Society of Anesthesiologists ASA class of II or higher, obesity, functional dependence, and congestive heart failure, increase the risk for postoperative pulmonary complications. Rationale for postoperative NIV use is the same as the post-extubation NIV use plus the specificities due to the respiratory modifications induced by the surgery and anesthesia. Postoperative NIV improves gas exchange, decreases work of breathing and reduces atelectasis. The aims of this article are (1) to review the main respiratory modifications induced by surgery and anesthesia which justify postoperative NIV use (2) to offer some recommendations to apply safely postoperative NIV and (3) to present the main results obtained with preventive and curative NIV in a surgical context.