Rectosigmoid pHi monitoring during experimental necrotizing enterocolitis

Background/Porpose: Gastric or rectosigmoid intramural pH (pHi) is consider ed a reliable indicator of splanchnic perfusion. The aim of this study was to evaluate whether rectosigmoid pHi reflects the severity of bowel damage in experimental necrotizing enterocolitis (NEC). Methods: A total of 36 neonatal piglets, (median age, 3; range, 1 to 11 day s; median weight, 2.5; range, 1.2 to 3.8 kg), were anesthetized, ventilated mechanically, and had invasive monitoring of hemodynamics. A sigmoid tonom eter was inserted into the rectosigmoid colon. Enterocolitis was induced in 27 piglets by intraluminal injection of casein-d-gluconate (16.0 mUkg) int o terminal 100 cm of the ileum. Nine control piglets received an equal amou nt of intraluminal saline. NEC was graded macroscopically as follows: 0, no changes; 1, mild; 2, moderate; and 3, severe. Histology was evaluated acco rding to Chiu scale from 0 to 5. Results: The macroscopical bowel injury in caseine-injected piglets was as follows: grade 3 (n = 6), grade 2 (n = 9), grade 1 (n = 12). All control pi glets showed macroscopically normal bowel (grade 0). All affected bowels sh owed histologic changes (Chiu's scale 2 to 4). All study animals had an ini tial drop of pHi after injection of casein or saline. In control piglets an d those with mild NEC (grade 1) pHi tended to return to preinjection level. In animals with moderate or severe NEC (grade 2 to 3) the initial drop was deeper and the pHi continued to decrease significantly throughout the expe riment (P < .05). In the arterial pH and mean blood pressure there were no statistically significant differences between piglets with no NEC and mild NEC, and these with moderate or severe NEC. Conclusion: Drop in rectosigmoid pHi was the most sensitive and earliest si gn of severe mucosal necrosis of ileum in this experimental NEC model. J Pe diatr Surg 35:1462-1467. Copyright (C) 2000 by W.B. Saunders Company.