Intraoperative Extracorporeal Support Research Articles

Intraoperative Extracorporeal Support during Lung Transplantation: Not Just for the High-Risk Patient.

The use of intraoperative mechanical support during lung transplantation has traditionally been a controversial topic. Trends for intraoperative mechanical support strategies swing like a pendulum. Historically, cardiopulmonary bypass (CPB) was the modality of choice during transplantation. It provides full hemodynamic support including oxygenation and decarboxylation. Surgical exposure is improved by permitting the drainage of the heart and provides more permissive retraction. CPBs contain drainage reservoirs with hand-held pump suction catheters promoting blood conservation through collection and re-circulation. But CPB has its disadvantages. It is known to cause systemic inflammation and coagulopathy. CPB requires high doses of heparinization, which increases bleeding risks. As transplantation progressed, off-pump transplantation began to trend as a preferable option. ECMO, however, has many of the benefits of CPB with less of the risk. Outcomes were improved with ECMO compared to CPB. CPB has a higher blood transfusion requirement, a higher need for post-operative ECMO support, a higher re-intubation rate, high rates of kidney injury and need for hemodialysis, longer ICU stays, higher incidences of PGD grade 3, as well as overall in-hospital mortality when compared with ECMO use. The focus now shifts to using intraoperative mechanical support to protect the graft, helping to reduce ischemia-reperfusion injury and allowing for lung protective ventilator settings. Studies show that the routine use of ECMO during transplantation decreases the rate of primary graft dysfunction and many adverse outcomes including ventilator time, need for tracheostomy, renal failure, post-operative ECMO requirements, and others. As intraoperative planned ECMO is considered a safe and effective approach, with improved survival and better overall outcomes compared to both unplanned ECMO implementation and off-pump transplantation, its routine use should be taken into consideration as standard protocol.

A prospective evaluation of phrenic nerve injury after lung transplantation: Incidence, risk factors, and analysis of the surgical procedure

Phrenic nerve injury (PNI) is a complication of lung transplantation related to the surgical procedure and associated with increased morbidity. However, the incidence and risk factors, specifically regarding surgical techniques, have not been adequately studied. We conducted a prospective single-center study over 4-years, in recipients of lung transplantation with a normal pretransplant phrenic nerve conduction study (PNCS). Diaphragm ultrasound and PNCS were performed in the first 21 postoperative days and PNI was defined when both tests were abnormal. Patients were followed up until hospital discharge. The association between transplant characteristics and PNI was analyzed by using logistic regression models. Two hundred eleven lung grafts implanted in 127 patients were included in the study. After lung transplantation, PNI was diagnosed in 43.3% of the subjects and 29% of the operated hemithorax. Regression logistic model showed that the variables related to PNI were female gender (p=0.02), bilateral lung transplantation (BLT) (p=0.001), right lung graft (p=0.003), clamshell incision (p=0.01), mediastinal adhesions (p=0.002), longer operative time (p=0.003), intraoperative extracorporeal support (p=0.02), and blood transfusion (p=0.003). Conversely, age >61 years (p=0.008) and higher thoracic diameter (p=0.04) were protective factors. The use of electrocautery, cardiac mechanical retractors, and diaphragmatic traction was not associated with PNI. Morbidity was increased without any difference in mortality. PNI is a frequent complication after lung transplantation, associated with higher morbidity. Mainly risk factors were age, BLT, female gender, and variables related to surgical difficulties. Lung graft in the right hemithorax and mediastinal adhesiolysis were the most relevant technical variables.

Intraoperative extracorporeal support during lung transplantation in patients bridged with venovenous extracorporeal membrane oxygenation.

Venovenous (VV) extracorporeal membrane oxygenation (ECMO) is the preferred configuration for bridging respiratory failure patients while awaiting lung transplantation. However, there is no consensus on intraoperative extracorporeal cardiopulmonary support during lung transplantation in these patients. The configuration of the intraoperative extracorporeal circuit after VV ECMO bridge was reviewed and correlated with clinical outcomes. This retrospective cohort study performed at our university hospital included 34 patients who were successfully bridged solely with VV ECMO to lung transplantation during the period 2007 to 2016. Indications to switch to intraoperative venoarterial (VA) ECMO were hemodynamic compromise (systemic hypotension or mean pulmonary artery pressure >40 mm Hg) or when this scenario was thought to be highly likely. The median duration of bridging was 12 (IQR 7 to 19) days. Intraoperatively, 3 patients (8.8%) required cardiopulmonary bypass. Twenty patients (58.8%) stayed on VV ECMO and 11 (32.3%) were switched to central VA ECMO. Between the 2 types of intraoperative ECMO (VV vs VA), there were no significant differences in post-operative ECMO duration, chest reopening for bleeding, or renal replacement therapy. There was no significant difference in 90-day mortality (0% and 9.0%, p = 0.35) or in long-term survival (p = 0.59). The intraoperative transfusion of red blood cells tended to be higher in the VA group (5 [4 to 9] vs 8 [6 to 13] units, p = 0.06). Use of intraoperative VA ECMO was associated with the use of low-flow VV device bridging and lobar transplantation. Using the existing VV ECMO bridge intraoperatively during lung transplantation is feasible and provides comparable outcomes to patients converted to central VA ECMO for compromised hemodynamics.