Hemodynamic and regional circulatory alterations in dog during anaphylactic challenge.

Microspheres were employed to measure the cardiac output (CO), percent distribution of CO (%CO), and blood flow (BF) to various tissues in the dog during anaphylactic shock. Five minutes after challenge there was a 66 and 83% drop from control for mean arterial pressure and CO, respectively. Arterial glucose and lactic acid rose 62 and 537%, respectively. Furthermore, there was a narrowing of the systemic arteriovenous difference for PO2 and a widening of the venoarterial difference for PCO2. Pressure compensation toward control values began 5 min postchallenge and continued through 180 min. Circulatory perturbations during severe hypotension (less than mmHg) included depressed %CO and BF to the pancreas and spleen and elevated %CO to the brain and adrenals. Cerebral and adrenal BF remained unchanged at this period. BF to the kidneys, liver (hepatic artery), and gastrointestinal tract dropped markedly as a function of increased peripheral resistance and decreased CO. As cardiac performance improved, blood flow to the pancreas, spleen, liver, diaphragm, and gastrointestinal tissues returned toward control but was elevated to the adrenals and decreased to the brain.