INTERRUPTION OF BRONCHIAL CIRCULATION LEADS TO A SEVERE DECREASE IN PERIBRONCHIAL OXYGEN-TENSION IN STANDARD LUNG TRANSPLANTATION TECHNIQUE

Objective: In clinical practice lung transplantation is the only proce dure where the transplanted organ is left without its own arterial per fusion. with the interruption of the bronchial arteries the nutritive support is dependent on collateral how by the pulmonary artery and the oxygen tension of desaturated central venous blood, representing an a bnormal physiology. Methods: To analyze this problem systematically, w e used a standard single left lung transplantation model in the pig (n = 12). In accordance with the clinical standard, lung preservation wa s performed with modified Euro-Collins solution with addition of prost acycline. The duration of ischemia was set to 4 h. Before and after si ngle left lung transplantation tissue oxygen tension in the peribronch ial tissue was measured with Licox(R) tissue pO(2) microprobes. For va lidation, the myocardial tissue oxygen tension was recorded simultaneo usly. The hemodynamic assessment included continuous flow measurement of the left and right pulmonary artery using Transsonic ultrasound how probes. After transplantation the animals were observed for 4 h. For hypothetic augmentation of collateral blood flow to the peribronchial tissue we administered Nitric oxide (10 ppm) to the ventilation in six pigs (group B). Six pigs (group A) served as a control without the ad dition of nitric oxide (NO). All pigs were ventilated with a FiO(2) of 0.5 resulting in paO(2) values between 160 and 200 mmHg. Results: In both groups single lung transplantation led to a significant decrease in peribronchial tissue oxygen tension throughout the observation peri od. Pre-Tx values of peribronchial tissue oxygen tension (38.31 +/- 6. 56 mmHg) decreased to 9.72 +/- 2.55 mmHg in group A and 10.3 +/- 3.61 mmHg in group B after 4 h, which could not be altered by a FiO(2) of 1 .0 (P < 0.0001). The addition of NO in group B led to a significantly augmented flow in the left pulmonary artery (0.63 +/- 0.31 l/min in gr oup B vs. 0.46 +/- 0.26 l/min group Al P < 0.001) representing 67 vs. 49% of the pre-Tx flow in groups B and A, respectively, but the peribr onchial tissue oxygen tension was not influenced (P > 0.05). In both g roups A and B, the central venous pO(2) did not differ in the postoper ative period (41.83 +/- 3.27 mmHg group A vs. 43.26 +/- 2.98 mmHg grou p B) and was kept in a comparable range to the pretransplantation valu es (45.23 +/- 3.41 mmHg pre-Tx). Conclusions: The persistence of a ver y low peribronchial tissue oxygen tension in the early phase after lun g transplantation cannot be influenced by improved pulmonary artery ho w and solely relates to the central venous pO(2), which cannot be augm ented by the addition of NO. This mechanism might be a trigger for ana stomotic healing problems, infectious complications and later developm ent of obliterative bronchiolitis (OB). (C) 1998 Elsevier Science B.V. All rights reserved.