Analytic study of laryngeal mask airway cuff pressure on the pharyngeal mucosa and postoperative adverse airway events

ABSTRACT

Sixty patients scheduled in order to calculate the pressure exerted by the cuff upon the pharyngeal mucosa and incidence of adverse airway events [hypoxia, hypercarbia, coughing, regurgitation, vomiting, airway obstruction, hiccup or biting]. At the end of surgery patients were interviewed about pharyngolaryngeal morbidity [sorethroat, dysphagia and dysphonia] immediately before leaving the post- anesthesia care unit and 24 hours following surgery. Patients were divided into three groups, each 20 patients were studied for each of the size 2, 3 and 4 laryngeal mask airway [LMA]. A noninvasive method was used to compare intracuff pressures. Cuff inflation with normal injection volumes recommended resulted in the residual volumes of the cuffs being exceeded. The intracuff pressures recorded with the mask in situ at these normal injection volume were in the range of 103-251 mmHg. The calculated transmitted mucosal pressures were substantial for all three sizes of the cuff and potentially exceeded the capillary perfusion pressure of the adjacent pharyngeal mucosa, despite apparent pharyngeal accommodation to the mask. Analysis showed more partial airway obstruction in the LMA size 2 group, also heart rate was slightly higher in LMA size 2 group upon arrival in the post- anesthetic care unit [PACU], otherwise there is no differences in cardio-respiratory responses. Sore throat and dysphagia were more common in the LMA size 2 group. The transmitted pharyngeal mucosal pressure were calculated over the clinical range of injection volumes. Study concluded that in general, emergence characteristics with the laryngeal mask airway are not influenced by volume of air used to inflate, but that postoperative sore throat and dysphagia are more likely at high initial cuff volumes