Measuring tissue oxygen saturation in the orad intestinal segment during equine colic surgery may aid in predicting the occurrence of postoperative ileus

OBJECTIVE To assess the histological injury and intestinal microperfusion measured by laser Doppler flowmetry and spectrophotometry (LDFS) of the small intestine orad to a strangulation during colic surgery. ANIMALS Horses with naturally occurring small intestinal strangulations undergoing colic surgery were included. METHODS In this prospective clinical trial, intestinal tissue oxygen saturation (tSO 2 ) and tissue blood flow (tBF) were measured by LDFS orad to the strangulation following release of the strangulation (n = 18). The number of horses with postoperative reflux (POR) and the cases that survived until discharge were compared between groups using Fisher’s exact test ( P < .05). Intestinal biopsies were taken in cases that underwent intestinal resection or intraoperative euthanasia (n = 28). Measurements were compared between injured and noninjured segments with a Mann-Whitney U or t test. RESULTS The tSO 2 and tBF of the orad intestine were lower than previously reported in healthy horses. Horses with low tSO 2 of < 35% were significantly more likely to suffer from POR (6/6 cases) compared to cases with tSO 2 > 69% (1/6). The number of horses that survived were not statistically different between these groups (2/6 and 6/6). All horses with mucosal injury developed POR (6/6), which was significantly more likely compared to horses without mucosal injury (3/13). No significant difference in tSO 2 or tBF could be found between the segments with and without histological injury. CLINICAL RELEVANCE The results suggest that measuring tSO 2 in the orad segment during colic surgery may aid in predicting postoperative issues.