Cardiorespiratory consequences of fluorocarbon reactions in dogs

Cardiorespiratory responses to 2 ml intravenous doses of fluorocarbon emulsions were investigated in dogs anaesthetised with pentobarbitone and artificially ventilated with air. Systemic and pulmonary artery pressures were measured using catheters in the femoral artery and external jugular vein. Oxygen consumption was obtained by analysis and measurement of expired gases and cardiac output was calculated using the Fick principle. Venous return from the hind limb was isolated using tourniquets at thigh and ankle regions and venous effluent was measured. Homogeneity of muscle blood flow was calculated using a saline washout technique. 24 of 28 dogs reacted to Oxypherol (FC-43) and 7 of 11 reacted to Fluosol-DA (FDA) (n.s.); 2 of 3 dogs unresponsive to FDA reacted to FC-43. The reactions consisted of severe, statistically significant, systemic hypotension with decreases in cardiac output and limb blood flow. Pulmonary and systemic vascular resistances were increased and body and limb muscle oxygen delivery and oxygen consumption were decreased. Reactions tended to be more severe following FC-43. Effects were maximal at 3-4 minutes after fluorocarbon administration. Changes had usually recovered at 40-60 minutes though oxygen debts were still being repaid. It is clear that acute myocardial depression was produced. Homogeneity of limb muscle flow was still significantly reduced at "recovery" and this we attribute to complement activation and embolisation of the microvasculature.