Resting Esophageal Sphincter Pressures and Deglutition Frequency in Awake Subjects After Oropharyngeal Topical Anesthesia and Laryngeal Mask Device Insertion

We investigated the effects of oropharyngeal topical anesthesia and placement of the standard (LMA) and the ProSeal (PLMA) laryngeal mask airway on resting gastroesophageal barrier pressure (GEBP), upper esophageal sphincter pressure (UESP), and deglutition frequency in awake subjects. Each subject was studied on 2 consecutive days: 1 day with the LMA and the other with the PLMA, in random order. GEBP and UESP were measured between deglutitions by using a pull-through technique in five sequential conditions: 1) after acclimatization to the manometer, 2) after topical anesthesia, 3) after the LMA or PLMA was self-inserted and the cuff inflated with either 10 or 30 mL of air in random order, 4) after the cuff volume was adjusted to the other randomized volume, and 5) after LMA or PLMA removal. Deglutition frequency was determined between pressure measurements by using a neck microphone. UESP was always larger than GEBP (P < 0.001 for all). Topical anesthesia had no influence on GEBP, UESP, or deglutition frequency. LMA and PLMA placement did not influence GEBP or UESP, but deglutition frequency was higher (P < 0.02 for all). GEBP and UESP did not vary between devices for any condition. Cuff volume did not influence GEBP or UESP. Deglutition frequency was more frequent for the LMA than the PLMA at a 30-mL cuff volume (P = 0.008). We conclude that resting GEBP and UESP are unaffected by oropharyngeal topical anesthesia and the LMA or PLMA in awake subjects, but that deglutition frequency is increased by the LMA or PLMA. This may have implications for the incidence of regurgitation in these situations.