Systemic and mesenteric hemodynamics, metabolism, and intestinal tonometryin a rat model of supraceliac aortic cross-clamping and declamping

Objective: To describe systemic and mesenteric hemodynamics, metabolism, an d intestinal tonometry in a rat model of supraceliac aortic cross-clamping and declamping. Design: Prospective, randomized, experimental study. Setting: University cardiovascular research laboratory. Participants:Twelve male anesthetized and ventilated Sprague-Dawley rats. Intervention: Supraceliac aortic cross-clamping was performed for 30 minute s, followed by declamping and reperfusion for 180 minutes or sham clamping and sham declamping. Measurements and Main Results: Mean arterial blood pressure; abdominal aort ic, superior mesenteric, and carotid artery blood flow; intestinal mucosal tonometry; hemoglobin; lactate; and blood gases were measured before and af ter 30 minutes of aortic cross-clamping and 15, 30, 60, 120, and 180 minute s after declamping during reperfusion. Aortic cross-clamping induced an inc rease in mean arterial pressure (117 +/- 20 mmHg to 147 +/- 12 mmHg), an in crease in right atrial hemoglobin saturation (66% +/- 11% to 81% +/- 6%), a n increase in lactate levels (1.7 +/- 0.7 mmol/L to 4.3 +/- 1.3 mmol/L), an d an increase in tonometric PCO2 (49.6 +/- 5.0 mmHg to 75.6 +/- 8.6 mmHg). Three hours of reperfusion after declamping resulted in significantly decre ased mean arterial pressure (38 +/- 10 mmHg); decreased aortic (101 +/- 12 mL/ min/kg to 57 +/- 32 mL/min/kg), mesenteric (19 +/- 4 to 13 +/- 6 mL/min /kg), and carotid (12 +/- 4 mL/min/kg to 5 +/- 3 mL/min/ kg) blood flows; a nd elevated lactate levels (4.2 +/- 2.0 mmol/L). Tonometric PCO2 had normal ized to baseline levels (51.9 +/- 3.8 mmHg), but PCO2 gap was significantly higher than in sham clamped rats (17.9 +/- 7.8 mmHg v 7.0 +/- 2.6 mmHg). Conclusions: Hemodynamic and metabolic effects of aortic cross-clamping and declamping known from large animal models are reproducible using a rat mod el. Intestinal tonometry indicated mesenteric ischemia during aortic cross- clamping, which was reversible to preclamp values within 30 minutes of repe rfusion after declamping. Copyright (C) 1999 by WB. Saunders Company.