Proportional Assist Ventilation and Respiratory Effort Monitoring During Transition to Spontaneous Breathing.
Gustavo Adrián Plotnikow, Facundo José Federico Bianchini, Roque Sebastián Moracci et al.
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In 30 seconds
This physiological randomized crossover study assessed whether the PAV+ work-of-breathing bar accurately reflects respiratory effort in 35 subjects being weaned from mechanical ventilation. Across three randomized assistance levels, its effort classification agreed with esophageal pressure-time product (PTP es-min) in 44.5% of cases (95% CI 32.9-56.4%), with negligible weighted κ of 0.01. The bar often underestimated effort, especially when effort was high. End-expiratory airway occlusion pressure (P occ) performed better, with 66.5% agreement (95% CI 57.9-75%) and κ of 0.35. The authors conclude that the bar is insufficient as a stand-alone guide for PAV+ titration.
Key findings
- The WOB-Bar classified effort in agreement with PTP es-min in 44.5% of cases (95% CI 32.9-56.4%); weighted κ was 0.01.
- P occ had 66.5% agreement (95% CI 57.9-75%) with PTP es-min, with κ of 0.35.
- WOB pt, P 0.1, and P occ were independent predictors of PTP es-min in a mixed-effects model (R 2 = 0.84).
- Inter-individual variability accounted for 77.5% of total variance in respiratory effort.
Why it matters
Accurate assessment of respiratory effort can inform ventilator assistance during weaning. These findings indicate that a convenient noninvasive display may not reliably identify effort categories and may miss high effort, while airway occlusion measures showed better agreement with the reference measure. The substantial between-subject variability also underscores the difficulty of applying uniform effort thresholds in this setting.
What to keep in mind
This was a physiological crossover study in 35 subjects, and the effort thresholds used were extrapolated from healthy individuals and are unvalidated during weaning. The findings are hypothesis generating.