Experimental aortic occlusion: A model for the study of regional shock with specific reference to blood lactate

A model of regional shock is described to study the dynamics of lactacidemia which accompanies perfusion failure. The suprarenal abdominal aorta was occluded with a balloon catheter to reduce the mean perfusion pressure to 25 mmHg in 5 dogs each for 60 and 120 minutes, while 5 dogs served as controls. Increases in arterial lactate from 2.4 r - 1.1 to 4.9 r - 1.2 mM/L were observed by 60 minutes. Lactate concentrations sampled from arterial and venous sites proximal and distal to the obstruction, showed good correlation (r=0.96) during and for 240 minutes following deflation of aortic balloon. Lactate clearance in experimental animals was accomplished by 90 minutes of re-establishment of flow to the lower extremities. Hemodynamic changes included tachycardia, upper body hypertension, with any increase in left ventricular filling pressures. Marked hemoconcentration observed in experimental animals was suggestive of plasma losses in splanchnic circulation, confirmed by autopsy findings of bowel edema and infraction, In this model of regional shock, absence of true lactate "washout" was also confirmed.