Myoelectric activity differences in acute and chronic models of lamb intestinal atresia

Clinical and experimental investigations of intestinal atresia have reduced mortality and clarified etiology. However, the morbidity of this lesion remains excessive and its pathophysiology uncertain. The purpose of this project was to produce the first long-term model of intestinal atresia and thereby to study the motility of the adapting bowel. Intestinal atresia was induced in nine fetal lambs at midgestation by mesenteric avulion. At term, this experimental group and eight control lambs underwent resection with anastomosis, decompression gastrostomy, and implantation of electrodes proximal and distal to the anastomosis. Vigorous resuscitation and constant intensive care were critical for survival. Slow wave activity (SWA) and spike potential activity (SPA) were recorded in the first 24 hours and every 48 hours thereafter for a 6-hour interval. Three of nine lambs with atresia and five of the eight control animals survived over 48 hours (chronic). Analysi of 220 hours of recording showed, in the first 24 hours of life, a statistically significantly different SWA of 16.4 cycles/min (±1.15 SD) in the chronic atretic survivors compared with 13.1 cycles/min (±2.6 SD) in the acute (died <48 hours) atretic group (P<.05). The SWA of the chronic atretic survivors was similar to the SWA of the chronic nonatretic control animals, 15.1 cycles/min (±1.4 SD). SPA was present on the first day of life in the microintestine of the chronic atresia group in contrast to the acute animals of this study and of Doolin and Hill's previous study. Delayed function has been atrributed to the absence of SPA in the microintestine of acute models. The data herein suggests that the appearance of SPA on the first day of life is coincident with the better overall condition of animals in the chronic atretic and control groups, and with long-term survival.