Anaphylaxis in the monkey: hemodynamics and blood flow distribution

Aggregate anaphylaxis was induced in eight ovalbumin-sensitized monkeys (Macaca irus). Hemodynamics, blood flow distribution and myocardial performance were studied. Following challenge, severe circulatory shock developed. Systemic arterial and left atrial pressures decreased and pulmonary arterial and right atrial pressures increased. There was a tenfold increase in pulmonary vascular resistance, and cardiac output was markedly reduced (-75%). A redistribution of the blood flow to vital organs (brain, heart and liver) occurred, at the expense of flow to other regions (muscles, kidneys, pancreas and spleen). There was also a redistribution of the blood flow within the myocardium, resulting in an unchanged right ventricular blood flow, despite a decrease in total myocardial blood flow. Right ventricular stroke work was reduced in spite of high filling pressures, whereas the decrease in left ventricular stroke work coincided with low filling pressures. It is concluded that the initial main cause of the low outflow state was an increased resistance in the pulmonary circulation followed by acute right heart failure.