How do antegrade enemas work? Colonic motility in response to administration of normal saline solution into the...

The aim of the study was to evaluate the colonic motor response to the administration of normal saline into the proximal colon.

Pediatric patients undergoing colonic manometry received a saline infusion (10-20 mL/kg) in 10 minutes through the central lumen of a catheter placed into the proximal colon. We compared the number of high-amplitude propagated contractions (HAPCs), motility index, frequency and propagation of other phasic contractions in the 20 minutes before and after normal saline infusion, meal ingestion, and bisacodyl administration.

Thirteen patients, mean age 9.4 ± 5.8 years, received the saline infusion (3 in the cecum, 8 in the hepatic flexure, and 2 in the transverse colon). In the first 20 minutes after saline infusion, the number of contractions (P = 0.005), distance of propagation of contractions (P = 0.007), frequency of contractions (P = 0.009), and motility index (P = 0.003) were significantly higher compared with baseline. Mean amplitude and number of HAPCs were not significantly different from baseline. Motility parameters after saline and after ingestion of a meal did not differ. All of the measured motility variables significantly increased after bisacodyl stimulation. Bisacodyl increased the motility index and HAPCs more than either saline infusion (P = 0.002) or meal intake (P < 0.001).

Infusion of saline into the proximal colon is associated with an increase in colonic motility; however, at the volume and rate used in the present study it does not consistently stimulate HAPCs.