Sex-dependent differences in regional lung mechanics; A retrospective observational study

Whether outcomes related to mechanical ventilation differ between men and women remains unclear. This study aims to investigate whether respiratory variables and regional lung mechanics in critically ill mechanically ventilated patients differ between men and women, and if so, whether anthropometric parameters could explain the difference.

In this retrospective observational study, mechanically ventilated patients who underwent an electrical impedance tomography measurement were included. During electrical impedance tomography measurements, incremental and decremental positive end-expiratory pressure trials were performed, and dynamic compliance, alveolar overdistension, and alveolar collapse were determined per positive end-expiratory pressure level. Respiratory and electrical impedance tomography variables were extracted, including total dynamic compliance/positive end-expiratory pressure steps per patient. Linear regression was used to compute differences in mean dynamic compliance/positive end-expiratory pressure steps between men and women.

A total of 259 patients (190 men and 69 women) were included and eligible for analysis. Comparisons of respiratory variables showed that women had higher tidal volumes per predicted body weight compared to men (7.7 mL/kg [6.6; 8.7] vs. 6.4 mL/kg [5.7; 7.3], p < 0.001). Women had lower dynamic compliance compared to men (4.8 mL/cmH₂O [-7.5; -2.1], p = 0.001), which was not statistically significant after adjusting for height (1.0 mL/cmH₂O [-4.6; 2.6], p = 0.593) and predicted body weight (0.5 mL/cmH₂O [-3.6; 4.7], p = 0.800).

The difference between dynamic compliance/positive end-expiratory pressure during electrical impedance tomography between men and women could be explained by the difference in height. These results provide insights into the ventilation management in ICU patients.