Jaw thrust as a predictor of insertion conditions for the proseal laryngeal mask airway.

We test the hypothesis that the response to jaw thrust is an effective predictor of insertion conditions for the ProSeal laryngeal mask airway (ProSeal LMA). One hundred and sixty patients (ASA grade 1-3, aged >18 yr) were studied. Five anesthetists blinded to the response to jaw thrust participated in the study, each performed >30 insertions. Induction of anesthesia was with propofol titrated to loss of lash reflex and apnea. A standard amount of jaw thrust was applied and any motor response noted by three observers. The ProSeal LMA was inserted using the standard digital technique. Insertion conditions were considered optimal if there was no motor or upper airway reflex response to insertion. There was no response to jaw thrust in 86% (137/160) of patients and insertion was optimal in 76% (121/160) of patients. A response to jaw thrust predicted suboptimal insertion conditions in 74% (17/23) and a lack of response predicted optimal insertion conditions in 84% (115/137). The accuracy, sensitivity and specificity were 0.82, 0.95 and 0.44, respectively. We conclude thatjaw thrust is a reliable predictor of insertion conditions for the ProSeal LMA with the digital insertion technique after induction of anesthesia with propofol. We suggest that clinicians learn how to apply the correct amount of jaw thrust and perform this test routinely.