[Analysis of the correlation between driving pressure and prognosis in lung transplant recipients based on restricted cubic spline model].

Objective: To investigate the correlation between postoperative driving pressure (DP) and the prognosis of lung transplantation, and to further evaluate the value of early DP monitoring in lung transplantation.

Methods: A observational study was conducted. The patients after lung transplantation who admitted to the intensive care unit (ICU) of Wuxi People's Hospital from February 1, 2022 to February 1, 2023 were collected. They were divided into low DP group (DP≤15 cmH₂O, 1 cmH₂O ≈ 0.098 kPa) and high DP group (DP > 15 cmH₂O) according to DP within 2 hours after operation. The clinical data including general information, primary disease, chronic diseases, cardiopulmonary function, laboratory indicators, intraoperative condition, postoperative lactic acid (Lac) and ventilator parameters were collected. Primary outcomes included 28-day and 90-day survival, and secondary outcomes included occurrence of primary graft dysfunction (PGD), duration of extracorporeal membrane oxygenation (ECMO), duration of mechanical ventilation, weaning of mechanical ventilation, and length of ICU stay. The general data and observations between the two groups were compared. Kaplan-Meier curve analysis was conducted to analyze the situation of mechanical ventilation and 90-day survival. Receiver operator characteristic curve (ROC curve) was used to evaluate the predictive ability of DP for failed weaning of mechanical ventilation and 90-day death. The dose-response relationship between DP and 90-day death risk was determined by restricted cubic spline model. Univariate analysis was performed using Cox proportional hazards model.

Results: A total of 101 patients were enrolled, with 68 patients (67.3%) in the low DP group and 33 patients (32.7%) in the high DP group. No statistically significant difference in general information, chronic diseases, primary diseases, cardiopulmonary function, laboratory indicators, intraoperative conditions, and postoperative Lac between the two groups was found. Compared with the low DP group, the patients in the high DP group had higher inspiratory pressure (Pinsp) and incidence of PGD with grade 3 at 24 hours after operation [Pinsp (cmH₂O): 21.0±0.6 vs. 20.0±0.7, PGD with grade 3 at 24 hours: 60.6% (20/33) vs. 39.7% (27/68), both P < 0.05], longer duration of ECMO, duration of mechanical ventilation, and the length of ICU stay [duration of ECMO (hours): 37 (21, 109) vs. 22 (14, 43), duration of mechanical ventilation (days): 3.1 (1.8, 10.7) vs. 1.9 (1.1, 3.2), length of ICU stay (days): 6 (3, 13) vs. 4 (3, 5), all P < 0.05], and lower successful weaning rate of mechanical ventilation [81.8% (27/33) vs. 95.6% (65/68), P < 0.05). The 28-day and 90-day survival rates in the high DP group were significantly higher than those in the low DP group [28-day: 69.7% (23/33) vs. 86.8% (59/68), 90-day: 63.6% (21/33) vs. 83.8% (57/68), both P < 0.05]. Kaplan-Meier curve showed that the patients in the low DP group were weaned and extubated earlier than high DP group, and the cumulative situation of weaning was better (Log-Rank test: χ ² = 14.054, P < 0.001), and the 90-day cumulative survival rate in the low DP group was significantly higher than that in the high DP group (Log-Rank test: χ ² = 4.791, P = 0.029). ROC curve analysis showed that the area under ROC curve (AUC) of DP for predicting 90-day death was 0.664 [95% confidence internal (95%CI) was 0.540-0.787, P = 0.017], and the AUC for predicting failed weaning of mechanical ventilation was 0.794 (95%CI was 0.667-0.921, P = 0.004). Results of restricted cubic spline model analysis showed that the 90-day death risk continued to increase with the DP < 18 cmH₂O; when DP≥18 cmH₂O, elevated DP did not continue to increase the 90-day death risk, showing a plateau effect. Univariate analysis showed that DP was independent risk factors of 90-day death, and the death risk increased by 9.3% for every 1 cmH₂O increase in DP [hazard ratio (HR) = 1.093, 95%CI was 1.007-1.186, P = 0.033].

Conclusions: DP is an independent risk factor of death after lung transplantation, and early postoperative DP may be used as a predictor of failed weaning of mechanical ventilation and 90-day death after lung transplantation.