Published in:
01-03-2009 | Experimental
Systemic and microcirculatory responses to progressive hemorrhage
Published in: Intensive Care Medicine | Issue 3/2009
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Objective
To compare systemic hemodynamics with microcirculatory changes at different vascular beds during progressive hemorrhage.
Setting
University-based research laboratory.
Subjects
Twelve anesthetized, mechanically ventilated sheep.
Interventions
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).
Conclusions
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.