CONTINUOUS HYPOPHARYNGEAL PH MEASUREMENTS IN SPONTANEOUSLY BREATHING ANESTHETIZED OUTPATIENTS - LARYNGEAL MASK AIRWAY VERSUS TRACHEAL INTUBATION

We measured the hypopharyngeal pH to compare the incidence of regurgit ation associated with the laryngeal mask airway (LMA) and the tracheal tube (TT) in spontaneously breathing, anesthetized patients. Sixty ou tpatients scheduled for elective peripheral surgery with a standardize d general anesthetic technique were randomly allocated to receive eith er a LMA (n = 28) or a TT (n = 32) for airway management. A 4-mm pH el ectrode was placed in the hypopharynx, and pH values were continuously collected and stored in a portable pH data logger system until the en d of the operation. There were no episodes of hypopharyngeal regurgita tion (pH < 4) detected during the course of measurement. At no time di d the hypopharyngeal pH value decrease below 5.5. The hypopharyngeal p H values in both groups were similar, ranging between 5.5 and 7.5, wit h median values of 5.7 and 6.2 in the LMA and TT groups, respectively. The pH in any given patient did not vary more than 1.0 unit from the initial value recorded at the start of the operation. We conclude that continuous monitoring of the hypopharyngeal pH in spontaneously breat hing, anesthetized outpatients failed to detect evidence of pharyngeal regurgitation.