Systemic and microcirculatory responses to progressive hemorrhage
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To compare systemic hemodynamics with microcirculatory changes at different vascular beds during progressive hemorrhage.
University-based research laboratory.
Twelve anesthetized, mechanically ventilated sheep.
Sheep were randomly assigned to HEMORRHAGE or CONTROL group. In the HEMORRHAGE group (n = 8), three stepwise bleedings of 5 ml/kg at 30-min intervals were performed to add up 15 ml/kg. In the CONTROL group (n = 4), sheep had the same surgical preparation but were not bled.
Measurements and main results
Progressive bleeding decreased cardiac output, and superior mesenteric artery blood flow, and systemic and intestinal oxygen transports from the first step of bleeding whereas systemic and intestinal oxygen consumption remained unchanged. Mean arterial blood pressure, arterial pH and base excess, and intramucosal-arterial PCO2 were only significantly modified in the last step of bleeding. Arterial lactate increased and sublingual, and intestinal serosal and mucosal capillary microvascular flow indexes and red blood cell velocities progressively decreased after the first step of bleeding (3.0 ± 0.1 vs. 2.3 ± 0.4, 3.2 ± 0.2 vs. 2.4 ± 0.6, 3.0 ± 0.0 vs. 2.0 ± 0.2, and 1,082 ± 29 vs. 977 ± 79, 1,042 ± 24 vs. 953 ± 60, 287 ± 65 vs. 262 ± 16 μm/s; P < 0.05 for all).
Alterations in sublingual, intestinal microcirculation, and arterial lactate simultaneously arose from the first step of bleeding. The microcirculatory changes were identified either by semi-quantitative flow index or by quantitative red blood cell velocity measurements.
KeywordsOxygen transport Blood flow Hemorrhage Microcirculation Intramucosal acidosis Lactate
Conflict of interest statement
Dr. Ince is Chief Scientific Officer of MicroVision Medical (an university-based company manufacturing sidestream dark-field devices) and holds patents and stock related to sidestream dark-field imaging. The remaining authors have not disclosed any potential conflicts of interest.
Supplementary material 2 (WMV 4.65 MB)
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