Splanchnic Circulation and Intraabdominal Metabolism in Two Porcine Models of Low Cardiac Output

Abstract

The impact of acute cardiac dysfunction on the gastrointestinal tract was investigated in anesthetized and instrumented pigs by sequential reductions of cardiac output (CO). Using a cardiac tamponade (n = 6) or partial inferior caval vein balloon inflation (n = 6), CO was controllably reduced for 1 h each to 75% (CO_75%), 50% (CO_50%), and 35% (CO_35%) of the baseline value. Cardiac output in controls (n = 6) was not manipulated and maintained. Mean arterial pressure, superior mesenteric arterial blood flow, and intestinal mucosal perfusion started to decrease at CO_50% in the intervention groups. The decrease in superior mesenteric arterial blood flow was non-linear and exaggerated at CO_35%. Systemic, venous mesenteric, and intraperitoneal lactate concentrations increased in the intervention groups from CO_50%. Global and mesenteric oxygen uptake decreased at CO_35%. In conclusion, gastrointestinal metabolism became increasingly anaerobic when CO was reduced by 50%. Anaerobic gastrointestinal metabolism in low CO can be detected using intraperitoneal microdialysis.

Keywords: Cardiac dysfunction; Cardiac tamponade; Caval vein balloon; Intraperitoneal microdialysis; Laser Doppler flowmetry; Porcine model.

Fig. 1

Cardiac output (CO, panel a, data are presented as medians and interquartile ranges) and survival (panel b) in anesthetized and mechanically ventilated pigs subjected to a graded reduction of CO to 75% (CO_75%), 50% (CO_50%), and 35% (CO_35%) of the baseline value by either cardiac tamponade (n = 6) or partial inflation of an inferior caval vein balloon (n = 6). In one group, no intervention was made (control, n = 6)

Fig. 2

Mean arterial pressure (MAP, panel a), heart rate (HR, panel b), central venous pressure (CVP, panel c), mesenteric venous pressure (MVP, panel d), superior mesenteric arterial blood flow (SMA, panel e), and intestinal mucosal perfusion (Muc. perf., panel f) in anesthetized and mechanically ventilated pigs subjected to a graded reduction of cardiac output to 75% (CO_75%), 50% (CO_50%), and 35% (CO_35%) of the baseline value by either cardiac tamponade (n = 6) or partial inflation of an inferior caval vein balloon (n = 6). In one group, no intervention was made (control, n = 6). Data are presented as medians and interquartile ranges. Asterisk, number, and currency symbols indicate a statistical difference (P < 0.05) between the caval vein balloon group and the control group, the cardiac tamponade group and the control group, and the caval vein balloon and cardiac tamponade groups, respectively

Fig. 3

Curve estimations for the blood flow index in the superior mesenteric artery (SMAI) and the cardiac index (CI) in anesthetized and mechanically ventilated pigs subjected to a graded reduction of cardiac output by cardiac tamponade or partial inflation of an inferior caval vein balloon and controls

Fig. 4

Global and mesenteric oxygen deliveries (DO₂, panela a and b, respectively), mixed-venous saturation (Mix.-ven. SO₂, panel c), mesenteric venous saturation (Mes. ven. SO₂, panel d), global and mesenteric oxygen uptakes (VO₂, panels e and f, respectively), and also systemic and mesenteric venous lactate concentrations (panels g and h, respectively) in anesthetized and mechanically ventilated pigs subjected to a graded reduction of cardiac output to 75% (CO_75%), 50% (CO_50%), and 35% (CO_35%) of the baseline value by either cardiac tamponade (n = 6) or partial inflation of an inferior caval vein balloon (n = 6). In one group, no intervention was made (control, n = 6). Data are presented as medians and interquartile ranges. Asterisk, number, and currency symbols indicate a statistical difference (P < 0.05) between the caval vein balloon group and the control group, the cardiac tamponade group and the control group, and the caval vein balloon and cardiac tamponade groups, respectively