Transient mesenteric ischaemic episodes tracked by continuous jejunal PCO2monitoring during liquid feeding

Objective: To test the effect of liquid feeds on the responses to splanchni c ischaemia of a continuous rapid response PCO2 sensor inserted in the jeju num. Design: Prospective experimental animal study in a university research labo ratory. Subjects: Adult male Wistar rats. Interventions: Adult male Wistar rats (285-425 g) were anaethetised with so dium pentobarbitone 60 mg/ kg i.p. and ventilated with 100 % oxygen and iso flurane via tracheostomy to a PaCO2 of 30-40 mmHg. A sensor was inserted in to the mid-jejunum to record PCO2 every second. Distal aortic pressure was transduced. Four control rats received no feeds whilst in another four rats liquid feed was infused into the proximal jejunum at 3 ml/h. In each rat f ive episodes of splanchnic ischaemia were induced by 2-min elevations of an aortic sling to a mean distal aortic pressure of 30 mmHg. Measurements and main results: PCO2 elevations were always detectable, usua lly less than a minute from the onset of splanchnic ischaemia in both fed a nd unfed rats, with no difference in mean times to detectable response. In the fed rats there was a small but significant increase in the time to peak sensor response (196 +/- 16 vs. 180 +/- 12 s) and a trend towards an eleva ted mean baseline luminal PCO2 (67 +/- 9 vs. 55 +/- 4 mmHg). Conclusions: B rief episodes of splanchnic ischaemia were tracked successfully by a rapid response jejunal continuous PCO2 sensor during the infusion of a proprietar y liquid feed preparation despite minor changes in PCO2 response characteri stics and a possible elevation in baseline luminal PCO2.