Theoretical effects of fluid infusions during cardiopulmonary resuscitation as demonstrated in a computer model of the circulation.

Recent studies have shown the potential adverse effects of venous volume loading on blood flow during closed chest cardiopulmonary resuscitation (CPR). To examine the effect of arterial and venous infusions, we employed a published computer simulation of the circulation during CPR. This model uses computer simulated electrical networks to model the heart and great vessels. CPR was modeled with compressions at a rate of 80/min and a force of 80 mmHg. Fluid infusions, simulated as current pulses into the abdominal aorta and superior vena cava, were given to measure their effect on myocardial and cranial blood flow. With 600 ml/min infusions into the abdominal aorta, there was a 12% peak increase in myocardial flow and a 3.8% peak increase in cranial flow. Every 100 ml/min increase in infusion from 0 to 900 ml/min produced a 1.4 ml/min linear increase in myocardial flow and a 4.2 ml/min linear increase in cranial flow. In agreement with previous CPR model studies, simulated vasoconstriction of abdominal and lower extremity vessels resulted in increased myocardial and cranial flows. As resistance of these vessels was increased, abdominal aortic infusions resulted in greater flow augmentations. In contrast to arterial results, infusions at 600 ml/min into the vena cava resulted in a 2.2% decrease in myocardial flow and a 0.62% decrease in cranial flow. Rise and fall times for initiation and cessation of flow augmentations were equal to four compression cycles. We conclude that these findings demonstrate the theoretical benefits of rapid arterial infusions during CPR with increases in myocardial and cranial blood flow. This method may provide an early temporary adjunct to myocardial perfusion during CPR.