Gastric feeding intolerance is not caused by mucosal ischemia measured by intragastric air tonometry in the critically ill

Background: Gastric mucosal ischemia may be a risk factor for gastrointestinal intolerance to early feeding in the critically ill. Aims: To study intragastric PCO<inf>2</inf> air tonometry and gastric residual volumes (GRV) before and after the start of gastric feeding. Methods: This is a two-center study in intensive care units of a university and teaching hospital. Twenty-nine critically ill, consecutive and consenting patients scheduled to start gastric feeding were studied after insertion of a gastric tonometry catheter and prior to and after start of gastric feeding (500ml over 1h), when clinically indicated. Results: Blood gasometry and intragastric tonometry were performed prior to and 2h after gastric feeding. The intragastric to arterial PCO<inf>2</inf> gap (normal <8mm Hg) was elevated in 41% of patients prior to feeding and measured (mean±standard deviation) 13±20 and 16±23mm Hg in patients with normal (<100ml, 42±34ml, n=19) and elevated GRV (250±141ml, n=10, P=0.75), respectively. After feeding, the gradient did not increase and measured 27±25 and 23±34mm Hg, respectively (P=0.80). Conclusion: Gastric mucosal ischemia is not a major risk factor for intolerance to early gastric feeding in the critically ill.

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