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

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.

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).

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.

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.