Changes in Driving Pressure vs Oxygenation as Predictor of Mortality in Moderate to Severe Acute Respiratory Distress Syndrome Patients Receiving Prone Position Ventilation

Background: Prone position ventilation (PPV) causes improvement in oxygenation, nevertheless, mortality in severe acute respiratory distress syndrome (ARDS) remains high. The changes in the driving pressure (DP) and its role in predicting mortality in moderate to severe ARDS patients receiving PPV is unexplored. Methods: A prospective observational study, conducted between September 2020 and February 2023 on moderate-severe ARDS patients requiring PPV. The values of DP and oxygenation (ratio of partial pressure of arterial oxygen to fraction of inspired oxygen [PaO₂/FiO₂]) before, during, and after PPV were recorded. The aim was to compare the DP and oxygenation before, during and after PPV sessions among moderate-severe ARDS patients, and determine the best predictor of mortality. Results: Total of 52 patients were included; 28-day mortality was 57%. Among the survivors, DP prior to PPV as compared to post-PPV session reduced significantly, from 16.36 ± 2.57 cmH₂O to 13.91 ± 1.74 cmH₂O (p-value < 0.001), whereas DP did not reduce in the non-survivors (19.43 ± 3.16 to 19.70 ± 3.15 cmH₂O (p-value = 0.318)]. Significant improvement in PaO₂/FiO₂ before PPV to post-PPV among both the survivors [92.75 [67.5–117.75]) to [205.50 (116.25–244.50)], (p-value < 0.001) and also among the non-survivors [87.90 (67.75–100.75)] to [112 (88.00–146.50)], (p-value < 0.001) was noted. Logistic regression analysis showed DP after PPV session as best predictor of mortality (p-value = 0.044) and its AUROC to predict mortality was 0.939, cut-off ≥16 cmH₂O, 90% sensitivity, 82% specificity. The Kaplan–Meier curve of DP after PPV ≥16 cmH₂O and <16 cmH₂O was significant (Log-rank Mantel-Cox p-value < 0.001). Conclusion: Prone position ventilation-induced decrease in DP is prognostic marker of survival than the increase in PaO₂/FiO₂. There is a primacy of DP, rather than oxygenation, in predicting mortality in moderate-severe ARDS. Post-PPV session DP ≥16 cmH₂O was an independent predictor of mortality.