CONTINUOUS SUBLINGUAL PCO2 AS A RAPID INDICATOR OF CHANGES IN TISSUE PERFUSION IN HEMORRHAGIC SHOCK

Abstract

Objective: sublingual pCO2 (slPCO2) correlates with tissue perfusion and severity of hemorrhage. However, its dynamic response properties under rapidly changing hemodynamic conditions are not well characterized. Methods: ten isofluraneanesthetized piglets were subjected to a standardized hemorrhage protocol consisting of repeated constant rate bleeding episodes designed to maintain mean arterial pressures (MAP) between 30 and 40 mmHg. Resuscitation was initiated when compensation was exhausted (MAP < 30 mmHg). We recorded continuous MAP, slPCO2 and calculated the rate of change of slPCO2 (dCO2), as well as the sample cross-correlation coefficients between MAP and slPCO2 (SCCC) for phase shifts up to 10 minutes. Results: hemorrhage resulted in significant fluctuations of MAP and high inter-individual variability of disease dynamics and outcome: 3 non-survivors, 7 survivors at 2 hours postresuscitation. Although slPCO2 showed inter-individual variability, dCO2 mirrored MAP changes. In 7 pigs, the most negative SCCC occurred with no phase shift between slPCO2 and MAP (Figure).FigureConclusion: Dynamic changes in slPCO2 quantified by dCO2 may be a sensitive, non-invasive indicator of hemorrhage-related changes in tissue perfusion with a response delay below our sampling interval of 5s.