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Abstract

Introduction: Early studies demonstrate that the change of sublingual microcirculation is a sensitive indicator of tissue perfusion. In this study, we investigated the changes of sublingual PCO2 (PslCO2) with different levels of blood loss and correlated with sublingual microcirculation in a pig model of hemorrhage. Hypothesis: We hypothesized that PslCO2 is also a sensitive indicator of the security of hemorrhage. Methods: Fifteen male domestic pigs weighing 33 - 37 kg were utilized. The animals were randomized to reduce estimated blood volume (EBV) by sham; 25% EBV; 35% EBV; 45% EBV over an interval of 30 min. The total blood volume was assumed as 70ml/kg body weight. The sublingual microcirculation was visualized with the aid of side-stream dark field imaging at baseline and at 30 min. Individual images were analyzed off-line for quantitating microvascular flow index (MFI) and perfused vessel density (PVD) of small vessel (<20 µm) by previously reported methods. PslCO2 was detected with the aid of a sublingual PCO2 sensor at the same time. Results: During hemorrhage, PslCO2 was progressively increased in 25%, 35% and 45% EBV groups (57 ± 5, 63 ± 6, 80 ± 10 Torr). Meanwhile, both MFI and PVD was progressively decreased (MFI, 2.75 ± 0.11, 1.08 ± 0.25 and 0.98 ± 0.12; PVD, 4.77 ± 0.23, 2.98 ± 0.1 and 2.8 ± 0.36 n/mm). Increases in PslCO2 was highly correlated with decreases in both MFI (r=0.684; P <0.05) and PVD (r=0.677; P <0.05). Conclusions: As sublingual microcirculation, PslCO2 was also a sensitive indicator of the security of hemorrhage.