Effect of prone position on ventilation-perfusion matching in patients with moderate to severe ARDS with different clinical phenotypes.

Summary

In a prospective, registered ICU study using contrast-enhanced EIT (N=25), prone positioning improved PaO2/FiO2 and V/Q matching earlier in focal and low D-dimer ARDS phenotypes (by 3 h) than in non-focal and high D-dimer phenotypes (by 6 h). Findings suggest tailoring prone duration by lung morphology and coagulation phenotype.

Key Findings

• PaO2/FiO2 improved at 3 h in focal ARDS but at 6 h in non-focal ARDS (both p<0.001).
• V/Q matching improved by 3 h in focal ARDS and by 6 h in non-focal ARDS.
• Low D-dimer ARDS showed earlier improvements (3 h) versus high D-dimer ARDS (6 h) in both oxygenation and V/Q.
• Study registered in ChiCTR (ChiCTR2200055442) and used contrast-enhanced EIT for V/Q assessment.

Clinical Implications

Consider longer prone sessions for non-focal or high D-dimer ARDS, while focal or low D-dimer phenotypes may benefit earlier. Incorporate morphology and D-dimer into proning protocols and monitoring.

Limitations

• Small single-center sample (N=25)
• Observational design limits causal inference
• Short observation window (first prone session only); no clinical outcomes beyond physiological endpoints

Future Directions

Randomized or protocolized trials testing phenotype-guided proning duration, integrating EIT-derived V/Q metrics and clinical outcomes.