Effect of Propofol on Internal Anal Sphincter Pressure During ARM

Background and Aim: An anorectal manometry (ARM) is a common test in the evaluation of outlet obstruction in constipation. In children under 6 yo, anesthesia is often used for patient comfort and compliance. The choice of anesthesia for ARM varies from center to center and includes the use of ketamine, inhalation agents, and propofol. With the increased use of propofol, our aim is to determine the effects of propofol on resting anal sphincter pressure while performing an ARM under general anesthesia.

Hypothesis: Propofol administration leads to a decrease in internal anal sphincter pressure.

Methods: This is a prospective, single center, observational study of the effect of propofol on the internal anal sphincter pressure. Pediatric patients between the ages of 2-6 years who require an anorectal manometry for chronic constipation will be offered enrollment. Anesthesia was required for patient compliance and comfort and conducted by an anesthesiologist. Sevoflurane was the inhalational agent used for induction. At Massachusetts General Hospital (MGH), 1 mg/kg of propofol bolus is routinely given at completion of the ARM test to reduce emergence delirium. The manometric probe was kept in place with continuous measurement of baseline internal anal sphincter pressure while propofol was administered. We measured changes to internal anal sphincter pressure and time to return to baseline.

Results: The primary outcomes will be change of internal anal sphincter pressure from baseline and time to return to baseline.

Discussion: The proposed investigation may demonstrate that propofol has an effect on the internal anal sphincter pressure which may affect its utility as an anesthetic for anorectal manometry.