Nerve injury and the laryngeal mask airway

The laryngeal mask airway is a widely used, non-invasive, general purpose airway. We report the case of a temporary vocal cord palsy following the use of such an airway. The development of inappropriately high cuff pressures secondary to nitrous oxide diffusion into the cuff is proposed as the most likely cause. Knowledge of the existence of nerve injuries complicating laryngeal mask use is particularly important when counselling certain patients. Mandatory intraoperative cuff pressure monitoring should lower the risk of subsequent voice problems.

Intracuff Pressure and Tracheal Morbidity

Background Diffusion of nitrous oxide into the cuff of the endotracheal tube results in an increase in cuff pressure. Excessive endotracheal tube cuff pressure may impair tracheal mucosal perfusion and cause tracheal damage and sore throat. Filling the cuff of the endotracheal tube with saline instead of air prevents the increase in cuff pressure due to nitrous oxide diffusion. This method was used to test whether tracheal morbidity is related to excess in tracheal cuff pressure during balanced anesthesia. Methods Fifty patients with American Society of Anesthesiologists physical status I or II were randomly allocated to two groups with endotracheal tube cuffs initially inflated to 20-30 cm H(2)O with either air (group A) or saline (group S). Anesthesia was maintained with isoflurane and nitrous oxide. At the time of extubation, a fiberoptic examination of the trachea was performed by an independent observer, and abnormalities of tracheal mucosa at the level of the cuff contact area were scored. Patients assessed their symptoms (sore throat, dysphagia, and hoarseness) at the time of discharge from the postanesthesia care unit and 24 h after extubation on a 101-point numerical rating scale. Results Cuff pressure increased gradually during anesthesia in group A but remained stable in group S. The incidence of sore throat was greater in group A than in group S in the postanesthesia care unit (76 vs. 20%) and 24 h after extubation (42 vs. 12%; P < 0.05). Tracheal lesions at time of extubation were seen in all patients of group A and in eight patients (32%) of group S (P < 0.05). Conclusion Excess in endotracheal tube cuff pressure during balanced anesthesia due to nitrous oxide diffusion into this closed gas space causes sore throat that is related to tracheal mucosal erosion.

Intraoperative herniation of a tracheostomy tube cuff

A case of intraoperative tracheostomy tube obstruction is reported. The clinical features and the chain of events leading to the diagnosis of cuff herniation are presented. The different mechanisms of herniation are discussed. In the present case we speculate that a manufacturing defect together with nitrous oxide diffusion into the cuff caused dilatation and herniation of the latter which led to obstruction of the distal tube lumen. We draw attention to this rare but life-threatening complication.