Replacing cardiopulmonary bypass with extracorporeal membrane oxygenation in lung transplantation operations

Cardiopulmonary bypass (CPB) support is required in some lung transplantation (LTX) operations. CPB support and full-dose heparin increases the risks of bleeding and early graft dysfunction. We report our experiences of replacing CPB with heparin-bonded low-dose heparin extracorporeal membrane oxygenation (ECMO) support in LTX surgery.

From 2003 to 2005 forty-seven patients were transplanted. Thirty-seven LTX patients were retrospectively evaluated for this study (10 patients were excluded due to heart-lung-, lung-kidney transplantation, LTX with bypass grafting, and ASD closure or emergency CPB support). Extracorporeal circulation support was necessary in 40% of the 37 LTX patients due to severe primary or secondary pulmonary hypertension (P or SPHTN), right heart dysfunction, or hemodynamic instability. There were seven LTX procedures with CPB and eight implantations with ECMO support. CPB (high-dose heparin) and ECMO support (ACT 160-220 s) was always set up through femoral veno-arterial canulation. All patients had limited access thoracotomies without transsection of the sternum. Normothermia was maintained in all patients. CPB patients: PPH 15%, COPD 15%, IPF with mean PAP>40 mmHg 70%. ECMO patients: PPH 13%, COPD 13%, IPF with severe PAP pressure elevation 74%.

In patients undergoing LTX for PPH, the ECMO support was directly extended into the post-operative period. Packed red blood cell (PRBC) transfusion requirements during the operation and the first 24h were 13.25+/-1.6 PRBC units versus 5.1+/-2.8 PRBC units on CBP (p=0.02). Operative time was longer (p=0.11) in the ECMO LTX (451 min+/-76 vs 346+/-140). The increased 90-day mortality rate of the ECMO patients showed a trend toward significance (p=0.056), which was related to infectious complications (3 vs 1 patient). Severe graft ischemia/reperfusion injury occurred in 9% in the CPB versus 13% in the ECMO group. The 1-year survival was significantly reduced in ECMO patients (p=0.004, log-rank test).

The advantages of femoral canulation rather than conventional central connections in lung transplantation procedures led to an undisturbed operative field. A significantly higher blood product amount was required in ECMO patients, which might lead to increased infection and mortality rates. CPB, obviously, should remain the standard support technique if extracorporeal circulation is required in lung transplantation surgery.