Esophageal-arterial PCO2 gradient during hemorrhagic shock in rats
Article
Totapally, BR, Torbati, D, Hultquist, K et al. (1999). Esophageal-arterial PCO2 gradient during hemorrhagic shock in rats
. CRITICAL CARE MEDICINE, 27(12 SUPPL.), A157. 10.1097/00003246-199912001-00451
Totapally, BR, Torbati, D, Hultquist, K et al. (1999). Esophageal-arterial PCO2 gradient during hemorrhagic shock in rats
. CRITICAL CARE MEDICINE, 27(12 SUPPL.), A157. 10.1097/00003246-199912001-00451
Introduction: Clinically, gastric-arterial PCO2 gradient is used to assess shock-induced intestinal hypoperfusion. Several drawbacks of gastric tonometry (intermittent nature and affect of gastric acidity) have been noted. We measured the distal esophageal-luminal PCO2 (P esophCO2)continuously with an indwelling PCO2 probe and determined PesophCO2-PaCO2 gradient in rats subjected to hemorrhagic hypotension, as an index of gut's hypoperfusion. Methods: Young, male rats were anesthetized, tracheotomized, and instrumented for i.v. infusion, arterial blood sampling, and MAP recording. A calibrated PCO2 probe (Paratrend 7)was orally inserted into distal third of esophagus. Anesthasia (15 mg/kg/h pentobarbitol), normothermia, and fluid balance (7 ml/kg/h) were maintained. Baseline values of MAP, gas-exchange, base excess (BE), hemoglobin concentration, and PesophCO2 were determined. Subsequently, each rat was subjected to two levels of hemorrhagic hypotension (15 and 30 ml/kg). At each level of hemorrhage, a 30 min interval was allowed for stabilization. All maesurements were repeated after stabilization period. The blood was collected in heparinized vials, maintained at 38°C, and was reinfused after the end of second stabilization period. All measurements were repeated thirty and 60 min after blood reinfusion. Results: Both levels of hemorrhagic hypotension significantly reduced P aCO2, blood hemoglobin, BE, and MAP, while the P esophCO2-PaCO2 gradient was significantly increased (Repeated measure ANOVA followed by Dunnett multiple comparision test; n=4). A significant correlation was found between the average BE and PesophCO2-PaCO2 gradient (n=5; r2=0.66; p<0.09). Except BE and PaCO2, all variable were completely recovered 30 min after reinfusion. Conclusions: Esophageal-arterial PCO2 gradient is increased during hemorrhagic shock in rats. Continuously measured PesophCO2 which is not affected by gastric acidity, may be a more useful tool for assessing gut's hypoperfusion in critical care conditions, compared to conventionally used intermittent gastric tonometry.
