[Risk Factors of Perioperative Pulmonary Aspiration Related to Anesthesia, Devices and Operation]

Perioperative pulmonary aspiration is an infrequent but is still a leading cause of anesthesia-related morbidity and mortality. This article reviews risk factors of perioperative pulmonary aspiration related to anesthesia, devices and operation. The most consistent risk factors related to anesthesia are light anesthesia, residual neuromuscular blockade after anesthesia, intermittent positive pressure ventilation particularly with high airway pressure, and prolonged anesthesia. The presence of a supraglottic airway inserted in hypopharynx, multiattempts at tracheal intubation, incorrectly inserted airway, the classic laryngeal mask, airway removal and cuff deflation during recovery of anesthesia, and exchange to a tracheal tube from supraglottic airway increase the risk of aspiration and regurgitation. Even if patients have no predisposing factors, they may become at risk of pulmonary aspiration from a surgical procedure. Patients who are undergoing emergency procedures, bariatric surgery, upper abdominal surgery and laparoscopic surgery should be considered at risk. Lithotomy or the head-down position may also encourage residual gastric contents to regurgitate.