Effects of partial versus complete aortic occlusion on macro and microcirculatory flows in swine hemorrhagic shock.

Abstract

INTRODUCTION: REBOA is a recognized rescue strategy in exsanguinating shock. Nevertheless, effects of partial- versus total-REBOA inflation on both macrocirculatory and microcirculatory splanchnic flows are not fully understood. METHODS: Controlled hemorrhagic shock was induced in 18 landrace pigs. After 30 minutes of shock, animals were randomly allocated to receiving partial-REBOA (n = 6), total-REBOA (n = 6), or no-REBOA (n = 6). Resuscitation with whole blood was initiated 25 minutes after balloon inflation (in both REBOA groups) or attaining shock (in no-REBOA group). Thereafter, the balloon was progressively deflated according to hemodynamic tolerance. Aortic root, femoral, and end-diastolic left ventricular pressures were monitored throughout the experiment. Simultaneous carotid, supra-celiac abdominal aorta and superior mesenteric artery flows were recorded, while microvascular flows at jejunal-serosa and mucosa were assessed by laser Doppler flowmetry (LDF) and sidestream dark-field video-microscopy. Mesenteric-venous blood samples were drawn to measure blood gases and lactate levels. All macrohemodynamic and microhemodynamic parameters were followed up to 4 hours of completing REBOA deflation (or its equivalent-time in no-REBOA group). RESULTS: Total-REBOA group showed the highest increase in aortic-root and coronary perfusion pressures during inflation, but these decreased significantly during reperfusion period, compared with partial- and no-REBOA ( p < 0.001). Partial- and total-REBOA groups showed significant decreases in superior mesenteric artery flow during reperfusion period compared with no-REBOA ( p < 0.001). However, partial-REBOA allowed some flow during inflation while enabling significantly better jejunal-microvascular flow assessed by LDF during reperfusion period, when compared with total-REBOA ( p = 0.048). The proportion of jejunal-villi with predominant continuous flow was significantly higher in partial- than total- or no-REBOA groups ( p < 0.01). The total-REBOA group had higher arterial and mesenteric-venous lactate levels both during occlusion and reperfusion periods ( p = <0.001; p = <0.001, respectively) when compared with partial-REBOA and no-REBOA groups. CONCLUSION: Partial-REBOA preserved regional-mesenteric and intestinal microcirculatory blood flow during both balloon occlusion and the early reperfusion period compared with total-REBOA. Partial-REBOA was also related with more favorable mesenteric venous pH and lactate values during balloon occlusion and reperfusion phases.