High-resolution solid-state manometry of the effect of rocuronium on barrierpressure.

Background: The pressure in the lower esophageal sphincter (LES) is partly dependent on striated muscles derived from the crural portion of the diaphragm. The effect of neuromuscular blockade on the integrity of the esophagogastric junction is not well studied. We conducted a prospective interventional study to determine the effect of rocuronium on the barrier pressure (LES pressure - intragastric pressure) of the esophagogastric junction. We also studied the effect of positive pressure ventilation on the barrier pressure after neuromuscular blockade with rocuronium.

Methods: Fourteen patients classified as American Society of Anesthesiologists classification system (ASA) I or II (aged 18-75 years) who presented for elective surgery (11 cholecystectomy, 3 inguinal hernia) participated in the study. Esophageal manometry was performed during anesthetization with propofol, fentanyl, and sevoflurane. The LES pressure was studied prior to anesthesia, after anesthesia induction during spontaneous breathing with laryngeal mask airway, after administration of rocuronium (0.6 mg/kg), and during positive pressure ventilation.

Results: Muscle relaxation with rocuronium showed no significant changes in barrier pressure when comparing the pressure immediately before rocuronium administration with the pressure obtained after rocuronium administration at the time point of 0% train-of-four (TOF). Conversion to positive pressure ventilation did not change the barrier pressure with inspiration or expiration. The greatest decrease in barrier pressure was measured after inducing anesthesia when comparing pressures during inspiration (P < 0.01).

Conclusions: Neuromuscular blockade with rocuronium and conversion from spontaneous breathing to positive pressure ventilation does not decrease the barrier pressure during anesthesia induction.