• L Oud and J A Kruse.
• Division of Pulmonary/Critical Care Medicine, Wayne State University School of Medicine, Detroit, Michigan, USA.
• J Crit Care. 1996 Sep 1; 11 (3): 144-50.

PurposeThe reproducibility of gastric intramucosal pH (pHi) determinations by saline-filled balloon tonometry has not been assessed adequately. We examined the agreement of pHi obtained using pairs of tonometry catheters under various conditions in a canine model of global hypoxia.MethodsTwo gastric balloon tonometry catheters were inserted into each of 16 anesthetized dogs. Cimetidine was administered to six of the animals (group 1). Hypoxia was induced for 30 minutes by reducing the F1O2 to 0.08. pHi was determined under basal conditions, at completion of hypoxia, and during the posthypoxic period.ResultsThe mean bias of the paired pHi determinations was 0.03 for group 1 and 0.00 for group 2 (P = NS). The corresponding 95% limits of agreement spanned 0.24 and 0.28 pH units, respectively. Agreement of pHi determinations between tonometry catheters was not significantly affected by varying of the equilibration period, by administration of cimetidine, or by the presence of posthypoxic conditions.ConclusionsClinically important disagreement was observed in simultaneous pHi determinations obtained using separate gastric balloon tonometry catheters exposed to identical in vivo conditions. Poor reproducibility of individual pHi determinations may limit the accuracy of pHi obtained by gastric balloon tonometry in the clinical setting.

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