• J Creteur, D De Backer, and J L Vincent.
• Department of Intensive Care, Erasme University Hospital, Free University of Brussels, Belgium.
• Crit. Care Med. 1999 Nov 1;27(11):2480-4.

ObjectiveTo define whether the gastric mucosal-arterial PCO2 gradient (PCO2 gap) reliably reflects hepatosplanchnic oxygenation in septic patients.DesignProspective observational clinical study.SettingAn adult, 31-bed medical/surgical department of intensive care of a university hospital.PatientsA total of 36 hemodynamically stable, invasively monitored, mechanically ventilated, sedated, paralyzed patients with severe sepsis.InterventionsIn each patient, hepatosplanchnic blood flow was determined by the continuous indocyanine green infusion technique and gastric mucosal PCO2 by the saline tonometry technique. Suprahepatic venous blood oxygen saturation and PCO2 also were measured. The mesenteric veno-arterial PCO2 gradient was determined as the difference between the suprahepatic venous blood PCO2 and the arterial blood PCO2.Measurements And Main ResultsThere were significant correlations between the hepatosplanchnic blood flow and the suprahepatic venous blood oxygen saturation (r2 = .56; p<.01), between the hepatosplanchnic blood flow and the mesenteric veno-arterial PCO2 gradient (r2 = .55; p<.01), and also between the suprahepatic venous blood oxygen saturation and the mesenteric veno-arterial PCO2 gradient (r2 = .64; p<.01). There was no statistically significant correlation between the PCO2 gap and the hepatosplanchnic blood flow, the suprahepatic venous blood oxygen saturation or the mesenteric veno-arterial PCO2 gradient.ConclusionsIn stable septic patients, the PCO2 gap is not correlated with global indexes of gut oxygenation. The interpretation of PCO2 gap is more complex than previously thought.

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