Effect of cardiopulmonary resuscitation on perfusion in a porcine model of severe hemorrhagic shock.

Background: Pulseless electrical activity from hemorrhagic shock has not been shown to benefit from cardiopulmonary resuscitation (CPR). Using a porcine model, our objective was to determine the effects of CPR on brain and skin oxygenation as a measure of perfusion in the setting of severe hemorrhagic shock.

Methods: Adult swine randomized to non-CPR and CPR were anesthetized. Tissue oxygen sensors were inserted into the parietal cerebral parenchyma and skin. Controlled hemorrhagic shock with mean arterial pressure (MAP) <30 mm Hg was achieved and allowed to persist for 10 minutes. Animals were randomized to either receive automated CPR or no treatment. They were then autotransfused with sufficient blood to achieve MAP >60 mm Hg. Measurements were obtained before, during, and after shock state. Outcomes were modeled using mixed-effects lognormal models.

Results: A total of 12 swine were used, and the results were analyzed (non-CPR, n = 5; CPR, n = 7). One animal in the CPR group died during shock. One cerebral probe sensor malfunctioned, and these data were excluded. Baseline characteristics were similar between groups. MAP during shock was similar between groups; however, the CPR group had significantly higher systolic blood pressure (62.8 vs. 48.8 mm Hg, p = 0.010) and lower diastolic blood pressure (12.8 vs. 27.8 mm Hg, p < 0.001). Both cerebral (pBO 2 ) and skin oxygenation (TcO 2 ) dropped significantly as a result of shock. The CPR group had lower overall measures of tissue perfusion during shock, but only TcO 2 at the shoulder was significantly lower during shock (11.5 vs. 21.1 mm Hg, p = 0.027) and recovery (33.3 vs. 62 mm Hg, p = 0.033).

Conclusion: Our model showed that adding CPR during hemorrhagic shock did not improve end-organ oxygenation/perfusion, but did significantly diminish skin perfusion. This experiment corroborates existing literature on the potential detrimental effects of CPR during hemorrhagic pulseless electrical activity, but further work is needed to confirm this observation.