In ARDS patients with higher recruitment-to-inflation ratio, PEEP 15 cm H₂O improved V/Q mismatch in both supine and prone positions, while worsening in lower R/I ratio patients in prone.
Does PEEP 15 cm H2O compared to PEEP 5 cm H2O improve V/Q mismatch in patients with moderate-to-severe ARDS in supine and prone positions?
High PEEP improves V/Q mismatch in ARDS patients with high lung recruitability in both supine and prone positions, but worsens it in prone position for those with low recruitability.
Absolute Event Rate: 0% vs 0%
High positive end-expiratory pressure (PEEP) may improve ventilation-perfusion (V/Q) mismatch in acute respiratory distress syndrome (ARDS) patients with high recruitability in supine position. However, impacts of PEEP on V/Q mismatch in prone position relative to supine position remain poorly understood. We aimed to compare PEEP effects between positions, and evaluate its relationship with lung recruitability. A total of 50 patients with moderate-to-severe ARDS were consecutively enrolled. Recruitment-to-inflation (R/I) ratio was used to measure baseline lung recruitability. V/Q mismatch, gas exchange, and respiratory mechanics were evaluated at PEEP 5 cm H 2 O and PEEP 15 cm H 2 O in supine position, followed by PEEP 5 cm H 2 O and PEEP 15 cm H 2 O in prone position. Median R/I ratio was 0.60 0.38, 0.72, separating patients with higher and lower R/I ratio. In patients with higher R/I ratio, PEEP 15 cm H 2 O (compared to PEEP 5 cm H 2 O) reduced shunt without significantly increasing dead space in both supine and prone positions, thereby improving V/Q mismatch (supine: 30.7 28.6, 36.8% at PEEP 15 cm H 2 O vs.38.0 34.9, 45.4% at PEEP 5 cm H 2 O, P < 0.001; prone: 25.7 21.4, 30.4% at PEEP 15 cm H 2 O vs. 32.8 27.5, 36.7% at PEEP 5 cm H 2 O, P < 0.001). However, in patients with lower R/I ratio, PEEP 15 cm H 2 O (compared to PEEP 5 cm H 2 O) in supine position did not improve V/Q mismatch (37.8 34.7, 42.1% at PEEP 15 cm H 2 O vs. 41.3 34.8, 45.4% at PEEP 5 cm H 2 O, P = 0.078), as the reduction in shunt was accompanied by a significant increase in dead space; in prone position, PEEP 15 cm H 2 O significantly worsened V/Q mismatch (35.9 28.3, 43.4% at PEEP 15 cm H 2 O vs. 31.7 24.3, 37.6% at PEEP 5 cm H 2 O, P < 0.001), as it failed to reduce shunt while significantly increasing dead space. In patients with higher R/I ratio, PEEP 15 cm H 2 O improved V/Q mismatch in both supine and positions. In patients with lower R/I ratio, PEEP 15 cm H 2 O did not impact V/Q mismatch in supine position but significantly worsened it in prone position.
Zha et al. (Thu,) reported a other. In ARDS patients with higher recruitment-to-inflation ratio, PEEP 15 cm H₂O improved V/Q mismatch in both supine and prone positions, while worsening in lower R/I ratio patients in prone.