Thromboxane interaction with cardiopulmonary dysfunction in graded bacterial sepsis.

The relationship between plasma levels of thromboxane A2, radioimmunoassayed as thromboxane B2 (TxB), and cardiopulmonary dysfunction in graded bacterial sepsis was investigated. Five adult female pigs under anesthesia were intubated and allowed to breathe room air spontaneously. Femoral arterial, venous, and pulmonary artery catheters were inserted. After a 60-minute control period Aeromonas hydrophila (1.0 X 10(9)/ml) was infused intravenously at 0.2 ml/kg/hr, gradually increasing to 4.0 ml/kg/hr over 4 hours. Arterial and mixed venous blood gases, hemodynamic measurements, and TxB plasma concentrations were obtained during the control period, at 10, 20, 30, 45, and 60 minutes and at 30-minute intervals thereafter. Cardiac index increased significantly from control at 20 minutes, remained above control levels for 1 hour, and then declined to significantly low values at 150 minutes. TxB was increased from control at 20 minutes, rising to four times control at 120 minutes. Mean arterial pressure, pulmonary capillary wedge pressure, left ventricular stroke work, paO2, and pvO2 decreased significantly during the experiment. Pulmonary artery pressure and pulmonary vascular resistance increased significantly. Changes in TxB were significantly cross-correlated with changes in cardiac index, pulmonary vascular resistance, stroke volume, left ventricular stroke work, and paO2. TxB elevations led the cross-correlated variables by 0 to 60 minutes. Pulmonary vascular resistance cross-correlated with mean arterial pressure and cardiac index. TxB is increased early in graded bacterial sepsis. Changes in TxB appear to precede impaired cardiopulmonary function. The data suggest that TxB is involved in the detrimental hemodynamic effects of early septicemia.