Edema development and recovery in neurogenic pulmonary edema

We determined the time course of changes in extravascular lung water (EVLW) that occur after massive sympathetic activation produced by intracisternal veratrine administration in chloralose-anesthetized dogs. Three groups of dogs were studied. In the first group (n = 9), acute increases in EVLW (occurring within minutes) were determined both by measuring extravascular thermal volume and by gravimetric analysis. In the second (n = 6) and third (n = 7) groups, changes in EVLW were followed for 2-3 h after veratrine administration. Extravascular thermal volume was measured in the second group. In the third group, right atrial injections of a vascular indicator (125I-labeled serum albumin) and an extravascular indicator (3HOH) were made while blood was sampled from the pulmonary artery (PA) and left atrium, and EVLW was determined by deconvolution of the left atrial and PA concentration-time curves. Indicator-dilution and gravimetric EVLW increased acutely only in dogs in which PA pressure exceeded 60 Torr, with two- to four-fold increases in EVLW being observed in dogs that developed the highest PA pressures (maximum 94 Torr). Thus, severe edema can develop rapidly after massive sympathetic nervous system activation but requires extreme degrees of pulmonary hypertension. In several dogs after the acute increase in EVLW associated with the pulmonary hypertension, the indicator-dilution EVLW decreased with time. These decreases appear to effect clearance of edema fluid rather than alterations in perfusion.