Association between patient–ventilator asynchrony and tcCO₂ during nocturnal NIV in COPD

Introduction: Patient–ventilator asynchrony (PVA) is common during chronic nocturnal noninvasive ventilation (NIV) in COPD. Its short-term effect on gas exchange remains debated. Aim: To determine whether PVA is associated with increases in transcutaneous CO₂ (tcCO₂) in COPD patients on chronic nocturnal NIV. Methods: Overnight NIV telemonitoring recordings from adults with COPD were analyzed offline. Ventilator pressure/flow waveforms were processed to automatically detect PVA—ineffective effort (IE), double-trigger (DT), and auto-trigger (AT). One-minute epochs were labeled “any PVA” if ≥1 IE/DT/AT event occurred. tcCO₂ SenTec® was synchronized with ventilator data via the Neuron® (Philips, Capsule). For each one-minute epoch at time t, ΔtcCO₂ was defined as tcCO₂(t+3 min) − tcCO₂(t). A prespecified 3-minute lag reflected physiologic and sensor response. Results: Across 20 recordings, ΔtcCO₂ increased during PVA epochs in 12/20 and decreased in 8/20. The median within-recording difference (PVA − no PVA) was +0.009 kPa (p = 0.139). Conclusion: Median tcCO2 was not different when PVAs occurred compared to time periods without PVA. However, the substantial variability across recordings indicates that in some patients PVA might affect gas exchange. These findings are preliminary; larger cohorts are needed to refine estimates, consider PVA subtypes, and identify subgroups where short-term CO₂ changes may be more pronounced.