Mechanical ventilation post-bilateral lung transplantation: A scoping review

BACKGROUND

Evidence from lung protective ventilation (LPV) in the acute respiratory distress syndrome has commonly been applied to guide periprocedural ventilation in lung transplantation. However, this approach may not adequately consider the distinctive features of respiratory failure and allograft physiology in the lung transplant recipient. This scoping review was conducted to systematically map the research describing ventilation and relevant physiological parameters post-bilateral lung transplantation with the aim to identify any associations with patient outcomes and gaps in the current knowledge base.

METHODS

To identify relevant publications, comprehensive literature searches of electronic bibliographic databases were conducted with the guidance of an experienced librarian in MEDLINE, EMBASE, SCOPUS and the Cochrane Library. The search strategies were peer-reviewed using the PRESS (Peer Review of Electronic Search Strategies) checklist. The reference lists of all relevant review articles were surveyed. Publications were included in the review if they described relevant ventilation parameters in the immediate post-operative period, published between 2000 and 2022 and involved human subjects undergoing bilateral lung transplantation. Publications were excluded if they included animal models, only single-lung transplant recipients or only patients managed with extracorporeal membrane oxygenation.

RESULTS

A total of 1212 articles were screened, 27 were subject to full-text review and 11 were included in the analysis. The quality of the included studies was assessed to be poor with no prospective multi-centre randomised controlled trials. The frequency of reported retrospective LPV parameters was as follows: tidal volume (82%), tidal volume indexed to both donor and recipient body weight (27%) and plateau pressure (18%). Data suggest that undersized grafts are at risk of unrecognised higher tidal volume ventilation indexed to donor body weight. The most reported patient-centred outcome was graft dysfunction severity in the first 72 h.

CONCLUSION

This review has identified a significant knowledge gap that indicates uncertainty regarding the safest ventilation practice in lung transplant recipients. The risk may be greatest in patients with established high-grade primary graft dysfunction and undersized allografts, and these factors may define a sub-group that warrants further investigation.

Diagnostic Yield of 18F-FDG PET After Lung Transplantation: A Single-center, Retrospective Cohort Study

BACKGROUND

To investigate the diagnostic yield of 18F-fluorodeoxyglucose positron emission tomography (18F-FDG PET) in lung transplant recipients.

METHODS

A single-center, retrospective cohort study including 234 18F-FDG PET examinations in 199 lung transplant recipients. Indication for PET referral, 18F-FDG PET diagnosis/findings and final clinical diagnosis were classified into 3 groups: malignancy, infection/inflammation not otherwise specified, and chronic lung allograft dysfunction with restrictive allograft syndrome phenotype. Sensitivity/specificity analysis was performed to determine accuracy of 18F-FDG PET in each group.

RESULTS

Sensitivity of 18F-FDG PET for malignancy was 91.4% (95% confidence interval, 82.5%-96.0%) and specificity was 82.3% (95% confidence interval, 74.5%-88.1%). Infection/inflammation not otherwise specified and restrictive allograft syndrome as indication for 18F-FDG PET comprised relatively small groups (14 and 31 cases, respectively). In addition, 18F-FDG PET revealed clinically relevant incidental findings in 15% of cases.

CONCLUSIONS

Referral for 18F-FDG PET after lung transplantation mainly occurred to confirm or rule out malignancy. In this specific setting, 18F-FDG PET has a high diagnostic yield. Accuracy of 18F-FDG PET for other indications is less clear, given small sample sizes. Clinically relevant diagnoses, unrelated to the primary indication for 18F-FDG PET, are found relatively often in this immunocompromised cohort.

Early pulmonary function and mid-term outcome in lung transplantation after ex-vivo lung perfusion - a single-center, retrospective, observational, cohort study

Outcomes after transplantation of lungs (LuTX) treated with ex-vivo lung perfusion (EVLP) are debated. In a single-center 8 years of retrospective analysis, we compared: donors' and recipients' characteristics, gas exchange and lung mechanics at ICU admission, 3, 6, and 12 months, and patients' survival of LuTX from standard donors compared with EVLP-treated grafts. A total of 193 LuTX were performed. Thirty-one LuTX, out of 50 EVLP procedures, were carried out: 7 from nonheart beating and 24 from extended criteria brain-dead donors. Recipients' characteristics were similar. At ICU admission, compared with standard donors, EVLP patients had worse PaO₂ /FiO₂ [276 (206; 374) vs. 204 (133; 245) mmHg, P < 0.05], more frequent extracorporeal support (18% vs. 32%, P = 0.053) and longer mechanical ventilation duration [28 days of ventilator-free days: 27 (24; 28) vs. 26 (19; 27), P < 0.05]. ICU length of stay [4 (2; 9) vs. 6 (3; 12) days, P = 0.208], 28-day survival (99% vs. 97%, P = 0.735), and 1-year respiratory function were similar between groups. Log-rank analysis (median follow-up 2.5 years) demonstrated similar patients' survival (P = 0.439) and time free of chronic lung allograft disease (P = 0.484). The EVLP program increased by 16% the number of LuTX. Compared to standard donors, EVLP patients had worse respiratory function immediately after LuTX but similar early and mid-term outcomes.