This is a prospective observational cohort study, approved by the Institutional Ethical Committee of Padua (reference number AOP2722). Written informed consent was obtained from each patient during the preoperative visit. All consecutive LT patients admitted to the Intensive Care Unit of the University Hospital of Padua were screened. Adult patients undergoing bilateral LT, not requiring invasive mechanical ventilation before surgery, were eligible for inclusion in the study only when they met the predefined 'readiness-to-wean' criteria on daily screening and were therefore deemed ready to undergone a first 30-min weaning trial. Exclusion criteria were: presence of neuromuscular blockers in the previous 12 hours, lack of ultrasound acoustic window, decline to participate, right hemi-diaphragmatic palsy due to surgical sacrifice of right phrenic nerve, duplicated patients.
The prevalence and adverse effect of diaphragm dysfunction (DD) after bilateral-lung transplant (LT) are still unclear, despite a well-known negative impact on weaning and outcome in other cohorts of critically ill and surgical patients.~Objects: The primary aim is investigating the prevalence of DD, assessed using point-of-care ultrasound and defined as diaphragm thickening fraction (TFdi) < 29%, at the first weaning trial after LT.~Secondary aims are investigating the impact of DD on weaning (defined success or failure according to pre-defined criteria, neuroventilatory efficiency (EAdi or NVE), perioperative (14-day) pneumonia, ICU length of stay (LOS), in-hospital mortality, and identifying potential risk factors for DD. Moreover, we aim to study the correlation between TFdi versus EAdi/NVE and the rapid shallow breathing index (RSBI), respectively.