The effects of intravenous nitroglycerine and norepinephrine on gastric microvascular perfusion in an experimental model of gastric tube reconstruction

Background. Esophagectomy with gastric tube reconstruction is the surgical treatment Jiff cancer of the esophagus. Perfusion of the anastomotic, site of the tube depends exclusively on microcirculation, making susceptible to hypoperfusion. It is unknown whether vasodilatation is superior to increased perfusion pressure to improve gastric tissue pm:fusion of the anastomosis. Methods. We performed a gastric tube reconstruction in 12 pigs, mean body weight 32 +/- 2 kg. Besides systemic hemodynamic parameters, gastric nun ovascular blood flow (MBF) was assessed with laser Doppler flowmetry and gastric microvascular HbO(2) saturation (mu HbSO(2)) and Hb concentration (mu Hbcon) with spectrophotometry Animals were randomized over 2 groups with and without intravenous nitroglycerin (NTG) In both groups, mean arterial pressure (MAP) was increased from 50 to 110 mmHg with infusion of norepinephrine; in the NTG group, central venous pressure was maintained below 10 mmHg, throughout the experiment with NTG Results. Except for central venous and pulmonary capillary wedge pressures all hemodynamic parameters were similar in both groups. Especially in corpus and fundus, MBF decreased following singery However, overall MBF was significantly higher in the NTG group Increasing MAP had no effect on fundus MBF Gastric mu HbSO(2) and mu Hbcon went not different between groups and did not change at higher MAP levels. Conclusion. In our experimental model of gastric tube reconstruction, tissue perfusion is severely compromised, this effect is aggravated by systemic hypotension independent from cardiac output Impaired venous outflow might contribute to this effect and can be counteracted with infusion of nitroglycerine. (Surgery 2010, 148 71-7)