Comparisons Between Sublingual and Gastric Tonometry During Hemorrhagic Shock

Abstract

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. Prospective animal study. Animal laboratory in a research institution. Domestic pigs. 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. 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. Under experimental conditions of hemorrhagic shock, sublingual capnometry yielded measurements that were interchangeable with those of gastric tonometry.