Comparisons between sublingual and gastric tonometry during hemorrhagic shock.

Abstract

STUDY OBJECTIVES: To compare sublingual tissue PCO(2), a disarmingly simple and noninvasive measurement of the severity of perfusion failure, with gastric tonometric PCO(2) during hemorrhagic shock in five male domestic pigs weighing 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 Wigger's method. BP was maintained at 50 mm Hg for 120 min followed by reinfusion 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 decreased 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 increased from 1.2 to 13.9 mmol/L. Sublingual PCO(2) (PslCO(2)) increased from 59 to 105 mm Hg, and gastric PCO(2) increased from 61 to 111 mm Hg. The correlation between time-coincident sublingual and gastric measurements of PCO(2) was r = 0.91 (p<0.0001). Bland-Altman analyses demonstrated a close correspondence between the two measurements. The reinfusion of shed blood promptly reversed the hemodynamic abnormalities and reestablished gastric and PslCO(2) to near baseline values. This contrasted with a delayed reversal of lactic acidosis. CONCLUSIONS: Under experimental conditions of hemorrhagic shock, sublingual capnometry yielded measurements that were interchangeable with those of gastric tonometry.