Intraoperative Serosal Extracellular Mapping of the Human Distal Colon: A Feasibility Study

Abstract

Background:Cyclic motor patterns (CMP) are the predominant motor pattern in the distal colon, and are important in both health and disease. Their origin, mechanism and relation to bioelectrical slow-waves remain incompletely understood. During abdominal surgery, an increase in the CMP occurs in the distal colon. This study aimed to evaluate the feasibility of detecting propagating slow waves and spike waves in the distal human colon through intraoperative, high-resolution (HR), serosal electrical mapping. Methods:HR electrical recordings were obtained from the distal colon using validated flexible PCB arrays (6 x 16 electrodes; 4 mm inter-electrode spacing; 2.4 cm2, 0.3 mm diameter) for up to 15 minutes. Passive unipolar signals were obtained and analysed.Results:Eleven patients (33-71 years; six females) undergoing colorectal surgery under general anaesthesia (4 with epidurals) were recruited. After artifact removal and comprehensive manual and automated analytics, events consistent with regular propagating activity between 2-6 cpm were not identified in any patient. Intermittent clusters of spike-like activities lasting 10-180 s with frequencies of each cluster ranging between 24-42 cpm, and an average amplitude of 0.54 ± 0.37 mV were recorded.Conclusions:Intra-operative colonic serosal mapping in humans is feasible, but unlike in the stomach and small bowel, revealed no regular propagating electrical activity, although sporadic, synchronous spike-wave events were identifiable. Alternative techniques are required to characterise the mechanisms underlying the hyperactive CMP observed in the intra- and post-operative period.