Noninvasive detection of ischemic bowel

Purpose: Acute mesenteric arterial occlusion is an abdominal catastrophe th at carries high morbidity and mortality rates. Current diagnostic methods, however, lack sensitivity and specificity and do not provide information ab out the viability of the affected bowel. Early diagnosis and intervention w ould improve patient outcomes and survival rates. The basic electrical rhyt hm (BER) is the omnipresent electrical slow wave of the gastrointestinal tr act that characterizes the underlying electrical activity of the bowel, BER frequency is known to fall with ischemia. Superconducting quantum interfer ence devices (SQUIDs) can detect BER by measuring the magnetic fields gener ated by the electrical activity of the smooth muscle of the small bowel. Th e purpose of this study was to determine the ability of a SQUID to detect m esenteric ischemia in a free-lying section of small bowel in an animal mode l of acute superior mesenteric artery occlusion. Methods: Seven adult male rabbits (six experimental and one control) were s tudied with transabdominal SQUID and electrode recordings during baseline a nd after the induction of mesenteric ischemia with balloon occlusion of the superior mesenteric artery. Continuous recordings were taken for 120 minut es of ischemia and analyzed with autoregressive spectral analysis to determ ine the BER frequency during specific time points of the study. Two indepen dent investigators blinded to the experimental preparation examined the res ults to determine whether there was decreased BER frequency and thus ischem ia. The results are expressed as mean +/- SEM, and paired t tests were used to determine statistical significance, Results BER was detected in all seven animals and fell from 10.7 +/- 0.5 cp m to 7.0 +/- 1.8 cpm after 30 minutes of ischemia in the magnetic channels (P < .05, with t test). The fall in BER was detected by the SQUID in all si x experimental animals. The blinded observers correctly identified healthy and ischemic magnetic data recording, with a sensitivity of 94% and specifi city of 100%. Conclusion: SQUIDs can noninvasively detect bowel ischemia early in a free- lying segment of small bowel in this animal model with a high degree of sen sitivity and specificity.