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.