The role of mechanical ventilation in primary graft dysfunction in the postoperative lung transplant recipient: A single center study and literature review

Background: Primary graft dysfunction (PGD) is still a major complication in patients undergoing lung transplantation (LTx). Much is unknown about the effect of postoperative mechanical ventilation on outcomes, with debate on the best approach to ventilation. Aim/Purpose: The goal of this study was to generate hypotheses on the association between postoperative mechanical ventilation settings and allograft size matching in PGD development. Method: This is a retrospective study of LTx patients between September 2011 and September 2018 (n = 116). PGD was assessed according to the International Society of Heart and Lung Transplantation (ISHLT) criteria. Data were collected from medical records, including chest x-ray assessments, blood gas analysis, mechanical ventilator parameters and spirometry. Results: Positive end-expiratory pressures (PEEP) of 5 cm H₂O were correlated with lower rates of grade 3 PGD. Graft size was important as tidal volumes calculated according to the recipient yielded greater rates of PGD when low volumes were used, a correlation that was lost when donor metrics were used. Conclusion: Our results highlight a need for greater investigation of the role donor characteristics play in determining post-operative ventilation of a lung transplant recipient. The mechanical ventilation settings on postoperative LTx recipients may have an implication for the development of acute graft dysfunction. Severe PGD was associated with the use of a PEEP higher than 5 and lower tidal volumes and oversized lungs were associated with lower long-term mortality. Lack of association between ventilatory settings and survival may point to the importance of other variables than ventilation in the development of PGD.