Effect of a novel prosthetic anal neosphincter on human colonic blood flow

Abstract

Background. An artificial anal sphincter has been developed which aimed to simulate the normal physiology of the anorectum. As a prelude to human implantation the present study reports the effect of inflation of this device on colonic perfusion in patients undergoing colectomy, which was assessed by using a laser Doppler scanner. Methods. Eleven patients (median age 49.8 (range 24.3-78.7) years) were studied. Five patients had inflammatory bowel disease (IBD). The neosphincter was placed around the bowel and progressively inflated. The model was designed so that blood flow changes to the colon under the neosphincter would be reflected in the distal segment of the bowel, which could be scanned by the laser Doppler scanner. Results. The blood flow in the colon distal to the device was significantly higher in patients with IBD (mean (s.e.m.) 288.6 (71.9) versus 211.1 (57.6) perfusion units; P < 0.001). The mean (s.e.m.) 'biological zero' value was 46 (14) perfusion units. Blood flow distal to the neosphincter decreased progressively with increased sphincteric compression by 0.66 per cent per mmHg applied pressure in controls and 0.35 per cent per mmHg in patients with IBD (P < 0.05). Conclusion. These results suggest that at the planned operating occlusion pressure (less than 45 mmHg) this neosphincter should not put the vascularity of the human colon at risk.