Postoperative respiratory failure in liver transplantation: Risk factors and effect on prognosis

Abstract

Background: Postoperative respiratory failure (PRF, namely mechanical ventilation >48 hours) significantly affects morbidity and mortality in liver transplantation (LTx). Previous studies analyzed only one or two categories of PRF risk factors (preoperative, intraoperative or postoperative ones). The aims of this study were to identify PRF predictors, to assess the length of stay (LoS) in ICU and the 90-day survival according to the PRF in LTx patients.

Methods: Two classification approaches were used: systematic classification (recipient-related preoperative factors; intraoperative factors; logistic factors; donor factors; postoperative ICU factors; postoperative surgical factors) and patient/organ classification (patient-related general factors; native-liver factors; new-liver factors; kidney factors; heart factors; brain factors; lung factors). Two hundred adult non-acute patients were included. Missing analysis was performed. The competitive role of each factor was assessed.

Results: PRF occurred in 36.0% of cases. Among 28 significant PRF predictors at univariate analysis, 6 were excluded because of collinearity, 22 were investigated by ROC curves and by logistic regression analysis. Recipient age (OR = 1.05; p = 0.010), female sex (OR = 2.75; p = 0.018), Model for End-Stage Liver Disease (MELD, OR = 1.09; p<0.001), restrictive lung pattern (OR = 2.49; p = 0.027), intraoperative veno-venous bypass (VVBP, OR = 3.03; p = 0.008), pre-extubation PaCO2 (OR = 1.11; p = 0.003) and Model for Early Allograft Function (MEAF, OR = 1.37; p<0.001) resulted independent PRF risk factors. As compared to patients without PRF, the PRF-group had longer LoS (10 days IQR 7-18 versus 5 days IQR 4-7, respectively; p<0.001) and lower day-90 survival (86.0% versus 97.6% respectively, p<0.001).

Conclusion: In conclusion, MELD, restrictive lung pattern, surgical complexity as captured by VVBP, pre-extubation PaCO2 and MEAF are the main predictors of PRF in non-acute LTx patients.

Fig 1. Frequencies of MELD in no-HCC and HCC patients.

(A) Histograms of MELD according to the outcome (PRF vs no-PRF) are reported. For each subset mean ± SD and median (IQR) are reported. (B) Frequencies and (percentages) are reported in PRF and no-PRF patients according to MELD ≥22 and MELD <22.

Fig 2. ROC curve analysis.

The Areas Under the Curve and Standard Errors are reported under each subset.

Fig 3. Survival analysis according with the PRF status.

Patient survival at 90 days was 97.6%±1.4% in the no-PRF group (continuous line), 96.4%±3.5% in the EF subgroup (dash-interrupted line), and 79.2%±6.2% in the WF subgroup (dot-interrupted line). Survival was significantly different between PRF and no-PRF groups (p<0.001) and, within PRF patients, between EF and WF- subgroups (p = 0.047). WF, but not EF patient’ survival, differed from that of no-PRF patients.