VENTILATION - PERFUSION MALDISTRIBUTION SECONDARY TO THE HYPERDYNAMIC CARDIOVASCULAR STATE AS THE MAJOR CAUSE OF INCREASED PULMONARY SHUNTING IN HUMAN SEPSIS

Cardiovascular and respiratory parameters were obtained in 374 studies from 151 patients (64 septic or septic shock and 87 with nonseptic cardiogenic syndromes). Cardiac output and related measures, respiratory parameters, pulmonary blood volume (DV/m2), cardiac ejection fraction (EFx), left ventricular end-diastolic volume (LVEDV), peripheral resistance (TPR), pulmonary shunt (QS/QT), physiologic dead space (VD/VT) and mean ventilation perfusion ratios (VA/QT) were calculated. Both physiologic evaluation and multivariable statistical analyses of the data were performed. For a given level of (A-aO2gradient/PaO2) septic patients have a higher QS/QTthan cardiogenic patients. Hyperdynamic septic patients have a larger QS/QT, a greater VD/VT, and a lower VA/QTand TPR than cardiogenics. The decrease in VA/QTand the rise in VD/VTare strong functions of the increased EFx, which raises cardiac index (Cl) and reduces LVEDV and the mean dispersion of pulmonary blood volume, thus causing hemodynamic redistribution of flow. QS/QTis mainly a direct function of the increase in Cl which also tends to reverse the EFx-mediated rise in VD/VT. The role of the septic mediated decrease in TPR as a contributing pathologic feature and the use of volume infusion to raise LVEDV and VA/QTin high-CI septics with large QS/QTis discussed. © 1979 by The Williams and Wilkins Co.