Artikel
Intraoperative quality assessment of tissue perfusion with indocyanine green (ICG) in a porcine model of mesenterial ischemia
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Veröffentlicht: | 21. April 2016 |
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Background: Intestinal ischemia as life-threatening event must be rapidly diagnosed and treated, but still intraoperative evaluation of bowel perfusion remains subjective and treatment strategies depend on the surgeon´s personal experience. Especially detection of resection margins is important to improve patients’ outcome.
Aim of the present experimental study was to evaluate fluorescent-imaging (FI) using indocyanine green (ICG) for visual and quantitative assessment of bowel perfusion during and after ischemia in a porcine model.
Materials and methods: 16 pigs of either sex (54,2±2,9kg) underwent occlusion of upper mesenteric-side branch-artery occlusion for 3hours (group I, n=8), and 6hours (group II, n=8) via median laparotomy, followed by 60minutes of reperfusion. 3 areas were defined: ischemic bowel (D1), transitional zone (D2), and non-ischemic bowel (D3).
Hemodynamic parameters, transit-time flood flow (TTFM) of the mesenteric artery and partial pressure of tissue oxygen (tpO2) in D1 and D3 were continuously assessed.
FI was performed during baseline (T0), during occlusion of the mesenteric-sidebranch-artery (T1), during release occlusion (T2) and after 60 minutes reperfusion (T4).
Results: Study protocol including FI could successfully be performed during stable hemodynamics in all pigs.
TTFM flow was equal in both groups during T0 (69,7± 16,5 ml/min), decreased to 0±0ml/min during complete occlusion, and increased after reperfusion to highest values at T4 (group I: 60,7 ± 48,4 ml/min, group II: 97,1 ± 31,0 ml/min; n.s.). Increase of flow was significantly different at 15 and 30 minutes after reperfusion (p<0,05).
TpO2 decreased significantly in all groups during ischemia to increase again at reperfusion. Increase of tpO2 was higher in group 1 as compared to group 2 (group 1: 33,1±, group 2: 14,1±x, n.s.) but did never return to baseline values (T0:36,7±2,7 vs. T4: group I: 24,3±, group II: 14,8 ± 10,3; n.s.).
FI was assessed as baseline adjusted FI-Ratio. During occlusion FI-Ratio confirmed loss of perfusion in D1 (group1: 0,14±0,09; group 2: 0,08±0,05), showed decreased perfusion during D2 (group1: 0,55±0,38; group 2: 0,54±0,52), and increased perfusion in D3 (group1:1,87±1,36; group 1,25±0,71). After reperfusion the FI-Ratio in D1 increased in group 2 (1,83±1,18) indicating capillary leakage, while FI-Ratio was almost comparable to baseline in group 1 (0,99±0,82) indicating reversible perfusion deficit. After Reperfusion D2 showed increased fluorescent intensity in both groups as compared to baseline values (group 1: 2,02±1,95 vs. group 2: 1,49±0,89);D3 showed comparable values to baseline at the different measurements (group 1:0,92±0,5 vs. group 2: 1,12±0,78).
Conclusion: Visual and quantitative assessment of bowel perfusion is feasible in the experimental setting. Also differences in between the different perfusion zones can be evaluated by FI. 6 h ischemia with increased FI Ratio indicates capillary leakage, while fluorescence intensity comparable to baseline values as measured after 3 h ischemia indicates complete reversible perfusion deficiency. This might be promising tool for intraoperative assessment of bowels perfusion in the future.