Influence of the mean airway pressure trajectory on the mortality and AKI occurrence in septic shock patients with mechanical ventilation: insights from the MIMIC-IV database

Yukang Dong ^1,2 Changyan Yang ¹ Run Sun ² Jiangquan Fu ¹ Rui Huang ¹ Jia Yuan ¹ Ying Wang ¹ Jinni Wang ¹ Feng SHEN ^1*

• ¹ Guizhou Medical University Affiliated Hospital, Guiyang, Guizhou Province, China
• ² Guizhou Provincial People's Hospital, Guiyang, Guizhou Province, China

Background: Mean airway pressure (Pmean) is a known prognostic marker for mortality and adverse outcomes in mechanically ventilated patients. However, most previous studies have relied on static measurements, leaving the impact of Pmean trajectory on clinical outcomes in septic shock patients unclear. This study aimed to investigate the effect of Pmean trajectory on survival rates and acute kidney injury (AKI) incidence in septic shock patients undergoing mechanical ventilation (MV).Methods: A total of 956 eligible patients were included. Based on model fitting criteria, five distinct Pmean trajectory groups were identified: group 1 (low-stable), group 2 (high-descend), group 3 (medium-ascend), group 4 (high-stable), and group 5 (higher-stable). Compared to the low-stable trajectory (group 1), trajectories in groups 3, 4, and 5 were associated with significantly higher 30-day mortality risks (HR = 1.40, 95% CI = 1.03–1.88; HR = 1.47, 95% CI = 1.01–2.13; HR = 2.54, 95% CI = 1.53–4.2, respectively), while group 2 exhibited similar mortality rates to group 1 (HR = 0.88, 95% CI = 0.60–1.30). Logistic regression analyses revealed that groups 3, 4, and 5 were also significant risk factors for AKI occurrence (P < 0.05), with group 1 as the reference. Mediation analysis revealed that 20.5% (95% CI = 0.106–0.40) of the Pmean trajectory effect on AKI occurrence was mediated through cumulative fluid balance.Conclusions: Pmean trajectories were strongly associated with mortality and AKI incidence in septic shock patients receiving MV..