Anaesthesiologic Considerations for Intraoperative ECMO Anticoagulation During Lung Transplantation

Overview

Extracorporeal membrane oxygenation (ECMO) is a frequently used extracorporeal support measure during the intraoperative period in lung transplantation. A certain amount of anticoagulation, mainly unfractionated heparin (UFH), is used as part of ECMO support. One of the most common perioperative complications during lung transplantation is bleeding. An inadequately high dose of UFH can increase the risk of bleeding. In this study, the investigators hypothesised that a lower dose of UFH would decrease the risk of nonsurgical bleeding complications during lung transplantation and would not pose an increased risk of thrombotic complications for patients or ECMO circuits.

This study was designed as a single-centre, retrospective, observational study including all lung transplants between January 2020 and December 2022 within the Prague Lung Transplant Program Motol University Hospital. A total of 141 patients were transplanted during the study period. The exclusion criteria were lung transplant without intraoperative ECMO support, block heart-lung transplantation, ECMO bridge to lung transplant and planned postoperative ECMO. The inclusion criteria were lung transplantation performed with intraoperative ECMO support, central ECMO cannulation, and successful ECMO support termination at the end of the surgery. According to the study inclusion criteria, only lung transplants under intraoperative central ECMO cannulation with successful ECMO weaning were included. A total of 109 patients fulfilled the inclusion criteria. Thirty-two patients were excluded based on the following exclusion criteria: heart-lung transplant (HLTx) n=4, ECMO bridge n=4, transplantation (Tx) without ECMO n=8, and planned prolonged ECMO n=16. UFH was used for ECMO anticoagulation in all patients. The subjects were divided into two groups according to the UFH dose during the entire surgical procedure. In the first group, the dose of UFH was below or equal to 60 IU/kg/surgery. In the second group, the dose of UFH was above 60 IU/kg/surgery. A cut-off value of 60 IU/kg was determined according to the available literature review. Values ≤ 60 IU/kg/surgery were considered relatively lower doses, and values \> 60 IU/kg/surgery were considered higher doses of UFH. The UFH effect was monitored by activated clotting time (ACT) values. The intraoperative haemoglobin level target for red blood cells (RBCs) substitution was 100 g/l. The parameters that will be monitored intraoperatively in both groups are the total blood loss in millilitres and related to the patient's weight during the operation, the total amount of UFH administered to the patient during the procedure in international units (IU) and related to the patient's weight, and the consumption of blood derivatives during surgery such as red blood cells, fresh frozen plasma (FFP) and platelets. In both groups, ACT values will be monitored after the administration of UFH before ECMO cannulation. In the postoperative period, the investigators will monitor the development of hemothorax requiring surgical revision. The investigators consider surgical revision for hemothorax to be a significant bleeding complication. 30-day and 90-day mortality, ECMO- and patient-related thrombotic complications will be assessed.