The Association Between Extravascular Lung Water and Critical Care Outcomes Following Bilateral Lung Transplantation

Primary graft dysfunction (PGD) is a form of acute respiratory failure that complicates 30% of bilateral lung transplants. Higher grades of PGD correlate with higher severity of respiratory failure and unfavorable outcomes. Immediate PGD determination posttransplant‚ however, is not always predictive of PGD over subsequent days or intensive care unit outcomes. We aimed to evaluate whether extravascular lung water index (ELWI) measured immediately post bilateral lung transplant was associated with higher severity of PGD at 72 h and duration of mechanical ventilation. METHODS. We conducted a prospective, observational study of bilateral lung transplant patients admitted to the intensive care unit. ELWI measurements were performed at admission, 6, 12, 24, 36, 48, 60, and 72 h following transplant or until extubation. We evaluated the association between admission ELWI and 72-h PGD grade and duration of mechanical ventilation. RESULTS. Across 56 patients enrolled, 268 transpulmonary thermodilution measurements were conducted. At admission, median ELWI increased with PGD grade (grade 1: 9 mL/kg [interquartile range (IQR), 8–11 mL/kg]‚ grade 2 [10 mL/kg (IQR, 8–12 mL/kg)]‚ and grade 3 [17 mL/kg (IQR, 14–19 mL/kg); P < 0.001]). Using multivariable Poisson regression analysis adjusting for confounders, admission ELWI elevation was associated with higher severity of PGD at 72 h (incidence rate ratio [IRR], 1.06; 95% confidence interval, 1.01-1.12) and duration of mechanical ventilation (IRR, 1.62; 95% confidence interval, 1.23-2.14). The combination of an ELWI of ≥13 mL/kg and partial pressure of oxygen/fraction of inspired oxygen ≤ 100 within 6 h of admission had high sensitivity (75%) and specificity (100%) for grade 3 PGD at 72 h (area under the curve, 0.95) and performed better than ELWI or partial pressure of oxygen/fraction of inspired oxygen alone. CONCLUSIONS. Our exploratory study demonstrates an association between admission ELWI and high grades of PGD at 72 h and longer duration of ventilation. These results provide the impetus to study whether goal-directed ELWI algorithms can improve transplant outcomes.