Indication to ECMO during lung transplantation

Introduction: We studied the use of mean systemic-to-pulmonary pressure ratio (MAP/mPAP) to stratify the need of ECMO during lung transplantation. Methods: Subjects were stratified according to MAP/mPAP ratio measured over a 10 minutes pulmonary artery (PA) clamp test. Subjects with a ratio below (Low) or above (High) the median value of MAP/mPAP (1.8 [1.5-2.4]) were analysed according to scheduling characteristics, intraoperative variables, and outcomes. Results: 24 LTXs were included in the analysis. mPAP increased from 30 [25-36] to 36 mmHg [29-44] (P<0.001), and MAP/mPAP decreased from 2.4 ± 0.7 to 2.2 ± 0.8 (P<0.001). All ECMOs were instituted in subjects of the Low group (8/12 vs. 0/12, Low vs. High, respectively, P<0.001). MAP/mPAP index was an independent predictor of ECMO (multiple logistic regression analysis P 0.002). Use of post-operative ECMO was greater in the Low group (P 0.037); primary graft dysfunction at 72 hours (PGD T72), ICU and hospital stay and 30-days survival were similar between groups. Of the Low group subjects (n=12), 3 had ECMO instituted immediately after PA clamp because of severe hemodynamic instability (ECMO), 4 never went on ECMO (no ECMO), 5 needed ECMO soon after graft reperfusion (delayed-ECMO). Subjects with delayed-ECMO had more PGD T72 (4 vs 1 vs 0; delayed-ECMO vs ECMO vs no-ECMO; P=0.051), despite similar donor and recipient characteristics. Conclusion: Intra-operative MAP/mPAP ratio at the time of PA clamp test is easy to obtain and useful to stratify the need of ECMO during LTx. To delay ECMO is harmful.