gms | German Medical Science

Background: Evaluation of intestinal perfusion during various procedures remains still subjective and depends on the surgeon´s individual experience. Intraoperative quality assessment of tissue perfusion with indocyanine green (ICG) fluorescence using a near-infrared camera system has been described in different ways and indications. Our group previously developed a fluorescent-cardiac imaging device for quantitative assessment of myocardial perfusion. So far no quantitative assessment was performed for visceral perfusion.

Aim of the present study was the evaluation of fluorescent-imaging (FI) for quantitative assessment of intestinal perfusion in a gastric tube model in pigs, and to compare the results to gold-standard of tissue perfusion fluorescent microspheres (FM).

Materials and methods: 7 pigs of either sex (56,0±3,0 kg) underwent gastric tube formation after transection and ligation of the gastric arteries despite of the right gastroepiploic artery to avoid collateral blood-flow, and to imitate clinical setting.

After baseline assessment (T0), hypotension (T1) was induced by propofol (mean arterial pressure (MAP) < 60mmHg). Then propofol was paused to obtain normotension (T2, MAP 60-90mmHg). Finally hypertension (T3, MAP>90mmHg) was induced by norepinephrine.

Measurements were performed in three regions of interest (ROI) under standardized conditions: fundus (D1), corpus (D2), and pre-pyloric (D3). Hemodynamic parameters, transit-time flood flow measurement (TTFM) of the right gastroepiploic artery, were continuously assessed. FI, FM and partial pressure of tissue oxygen (tpO₂) were quantified in each ROI.

Results: Study protocol including FI, FM, and tpO₂ could successfully be performed during stable hemodynamics at each measurement point.

TTFM flow was 26,3 ± 8,3 ml/min at baseline, decreased to 15±6ml/min at T1, and increased during T2 (21,25 ± 10,79 ml/min) and T3 (25,57 ± 15,13 ml/min; n.s.).

In D1 tpO₂ in D1 was lower at T1 (19,97±11,8) and T3 (16,4±9,9), as compared to normotension (T2: 24,8±14,8); similar results were achieved by FI with highest fluorescent intensity during T2 as compared to T1 and T3; blood flow assessed by FM showed highest values during T3 (1,122 ml/min/g) as compared to T1 (1,037 ml/min/g) and T2 (0,916 ml/min/g);

Regarding the ROIs FI and FM measurements showed highest values in D3, and lowest values in D1 during all hemodynamic levels (T1-T3;p<0,05). While perfusion of D3 improved under increase of blood pressure, D1 and D2 remained stable.

Conclusion: Visual and quantitative assessment of gastric tube perfusion is feasible in the experimental setting using FI. This might be promising tool for intraoperative assessment visceral surgery in the future.