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

Abstract

Background: 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.

Methods: 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.

Results: 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.

Conclusions: 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.

Keywords: diaphragm; lung transplantation; phrenic nerve; postoperative complications; thoracic surgery.