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Background <p>Pendelluft and expiratory muscle activity during spontaneous breathing should be minimized to reduce potential harmful effects. This study aimed to describe pendelluft and expiratory muscle activity in hypoxemic patients recovering spontaneous breathing after ≥ 72&#xa0;h of lung-protective, fully controlled mechanical ventilation (MV) and assess the effect of pressure support ventilation (PSV) and positive end-expiratory pressure (PEEP).</p> Methods <p>A physiological, randomized crossover study was conducted in hypoxemic patients receiving three levels of PSV: 5, 10, and 15 cmH₂O, and two PEEP levels: based on electrical impedance tomography before spontaneous breathing (PEEP<sub>EIT</sub>) or according to PEEP-FiO<sub>2</sub> tables (PEEP<sub>ARDS</sub>). Pendelluft was defined as the percentage of volume displaced from non-dependent to dependent lung regions during inspiration. Expiratory muscle activity was assessed by the expiratory rise in gastric pressure (ΔPga<sub>EXP</sub>), and inspiratory effort was estimated using muscular pressure (Pmus). Statistical analyses included linear mixed-effects models and mediation analyses.</p> Results <p>Fifteen patients were enrolled (mean PaO<sub>2</sub>/FiO<sub>2</sub> ratio: 262 ± 51&#xa0;mmHg; median duration of MV: 9 [5–13] days; 6 females). PEEP<sub>EIT</sub> was 11 [10–13] cmH₂O and PEEP<sub>ARDS</sub> 6 [5–7] cmH₂O. Expiratory muscle activity was observed in 13 patients. Compared to PS 5 cmH<sub>2</sub>O, PS to 10 and 15 cmH<sub>2</sub>O, adjusted for PEEP, significantly reduced both pendelluft and ΔPga<sub>EXP</sub> (<i>p</i> &lt; 0.001). When adjusted for PS, PEEP<sub>EIT</sub> was associated with a slight reduction in pendelluft (<i>p</i> = 0.039) but a concomitant increase in ΔPga<sub>EXP</sub> (<i>p</i> = 0.007) compared to PEEP<sub>ARDS</sub>. The mediation analysis revealed a significant negative mediating effect of ΔPga<sub>EXP</sub> on the relationship between PEEP<sub>EIT</sub> and pendelluft (<i>p</i> &lt; 0.001). Pmus, which was also significantly associated with pendelluft magnitude (<i>p</i> &lt; 0.001), mediated the effect of PS on reducing pendelluft (<i>p</i> = 0.048), but not that of PEEP (<i>p</i> = 0.46).</p> Conclusions <p>In patients with ARDS transitioning to spontaneous breathing, increasing PS reduces pendelluft and expiratory muscle activity. Higher PEEP can decrease pendelluft, but its effect can be counteracted by increased expiratory activity.</p>

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Influence of ventilatory settings on pendelluft and expiratory muscle activity in hypoxemic patients resuming spontaneous breathing

  • 期刊论文

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  • 发表日期：

    2025年12月3日

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  • Rodrigo A. Cornejo,
  • Roberto Brito,
  • Carla Rivera,
  • Caio C. A. Morais,
  • Daniel H. Arellano,
  • Marioli T. Lazo,
  • Alejandro Fuentes,
  • Eduardo Paredes,
  • Verónica Rojas,
  • María F. Bravo,
  • María J. Martin,
  • Luz Miranda,
  • Juan N. Medel,
  • Alejandro R. Bruhn,
  • Jan Bakker,
  • Marcelo B. P. Amato,
  • Laurent J. Brochard,
  • Nivia R. Estuardo

摘要

Background

Pendelluft and expiratory muscle activity during spontaneous breathing should be minimized to reduce potential harmful effects. This study aimed to describe pendelluft and expiratory muscle activity in hypoxemic patients recovering spontaneous breathing after ≥ 72 h of lung-protective, fully controlled mechanical ventilation (MV) and assess the effect of pressure support ventilation (PSV) and positive end-expiratory pressure (PEEP).

Methods

A physiological, randomized crossover study was conducted in hypoxemic patients receiving three levels of PSV: 5, 10, and 15 cmH₂O, and two PEEP levels: based on electrical impedance tomography before spontaneous breathing (PEEPEIT) or according to PEEP-FiO2 tables (PEEPARDS). Pendelluft was defined as the percentage of volume displaced from non-dependent to dependent lung regions during inspiration. Expiratory muscle activity was assessed by the expiratory rise in gastric pressure (ΔPgaEXP), and inspiratory effort was estimated using muscular pressure (Pmus). Statistical analyses included linear mixed-effects models and mediation analyses.

Results

Fifteen patients were enrolled (mean PaO2/FiO2 ratio: 262 ± 51 mmHg; median duration of MV: 9 [5–13] days; 6 females). PEEPEIT was 11 [10–13] cmH₂O and PEEPARDS 6 [5–7] cmH₂O. Expiratory muscle activity was observed in 13 patients. Compared to PS 5 cmH2O, PS to 10 and 15 cmH2O, adjusted for PEEP, significantly reduced both pendelluft and ΔPgaEXP (p < 0.001). When adjusted for PS, PEEPEIT was associated with a slight reduction in pendelluft (p = 0.039) but a concomitant increase in ΔPgaEXP (p = 0.007) compared to PEEPARDS. The mediation analysis revealed a significant negative mediating effect of ΔPgaEXP on the relationship between PEEPEIT and pendelluft (p < 0.001). Pmus, which was also significantly associated with pendelluft magnitude (p < 0.001), mediated the effect of PS on reducing pendelluft (p = 0.048), but not that of PEEP (p = 0.46).

Conclusions

In patients with ARDS transitioning to spontaneous breathing, increasing PS reduces pendelluft and expiratory muscle activity. Higher PEEP can decrease pendelluft, but its effect can be counteracted by increased expiratory activity.