Comparisons between sublingual and gastric tonometry during hemorrhagic shock

Study objectives: To compare sublingual tissue PCO2, a disarmingly simple a nd noninvasive measurement of the severity of perfusion failure, with gastr ic tonometric PCO2 during hemorrhagic shock in five male domestic pigs weig hing between 35 and 40 kg. Design: Prospective animal study. Setting: Animal laboratory in a research institution. Participants: Domestic pigs. Interventions: Hemorrhagic shock was induced by a modification of the Wigge r's method, BP was maintained at 50 mm Hg for 120 min followed by reinfusio n of shed blood at a rate of 100 mL/min with the aid of an infusion pump. Measurements and results: During bleeding, the mean arterial pressure decre ased from an average of 127 to 42 mm Hg, and cardiac output decreased from 7.7 to 2.4 L/min. Arterial blood lactate concentration concurrently increas ed from 1.2 to 13.9 mmol/L, Sublingual PCO2 (PslCO(2)) increased from 59 to 105 nun Hg, and gastric PCO2 increased from 61 to 111 mm Hg. The correlati on between time-coincident sublingual and gastric measurements of PCO2 was r = 0.91 (p < 0.0001), Bland-Altman analyses demonstrated a close correspon dence between the two measurements. The reinfusion of shed blood promptly r eversed the hemodynamic abnormalities and reestablished gastric and PslCO(2 ) to near baseline values. This contrasted with a delayed reversal of lacti c acidosis. Conclusions: Under experimental conditions of hemorrhagic shock, sublingual capnometry yielded measurements that were interchangeable with those of ga stric tonometry.