Can Propofol be Used to Assess the Presence of the Rectoanal Inhibitory Reflex During Anorectal Manometry Studies

Objectives To study changes in intra-anal pressure (IAP) and characteristics of the rectoanal inhibitory reflex (RAIR) during anorectal manometry (ARM) in patients undergoing anesthesia induction with propofol. Methods Prospective study in which ARM was performed at baseline while patients were awake and repeated after propofol induced anesthesia. We studied IAP and the presence and characteristics of the RAIR before and after propofol. Results A total of 27 patients were included (63% male; 9.2 years). Three patients had obstructive symptoms after Hirschsprung's Disease repair (HSCR), and 24 had intractable constipation. At baseline the RAIR was present on 21/27 patients and absent in 6/27. Of the 6 patients with an absent RAIR, it remained absent in 4/6 (3 known HSCR, and 1 new diagnosis of IAS achalasia), and 2/6 had a normal RAIR during propofol. Therefore RAIR was present in all patients with constipation. The mean resting IAP was significantly lower after propofol. The percentage of IAS relaxation after lower balloon volume inflations was significantly higher during propofol (P < 0.05). No difference was observed over the latency time or the total relaxation time after propofol. Conclusions Propofol can be used to assess the presence of the RAIR during ARM in children who are uncooperative and undergoing other procedures under anesthesia. On the other hand propofol significantly reduces the resting IAP and increases the percentage of internal anal sphincter relaxation after balloon distention. These findings may impact the interpretation to decide if an intervention is needed, or if there is a possible spinal neuropathy.