Abstract
Rationale: Breathing is a cyclic activity that is by nature variable. Breathing variability is modified in mechanically ventilated (MV) patients.
Objectives: We aimed to evaluate whether decreased variability on the day of transition from assist-control ventilation to a partial mode of assistance was associated with a poorer outcome.
Methods: This was an ancillary study of a multicenter, randomized, controlled trial comparing neurally adjusted ventilatory assist to pressure support ventilation. Flow and the electrical activity of the diaphragm (EAdi) were recorded within 48 h of switching from controlled ventilation to a partial mode of ventilatory assistance.
Measurements: Variability of flow and EAdi-related variables were quantified by the coefficient of variation, the amplitude ratio of the spectrum's first harmonic to its zero-frequency component (H1/DC) and two surrogates of complexity,.
Main Results: Ninety-eight patients ventilated for a median duration of 5 days were included. H1/DC of inspiratory flow and EAdi were lower in survivors than in non-survivors, suggesting a higher breathing variability in this population (for flow, 37% versus 45%, p=0.041; for EAdi, 42% versus 52%, p=0.002). By multivariate analysis, H1/DC of inspiratory EAdi was independently associated with day-28 mortality (odds ratio 1.10, p=0.002). H1/DC of inspiratory EAdi was lower in patients with a duration of MV<8 days (41% versus 45%, p=0.022). Noise limit and the largest Lyapunov exponent suggested a lower complexity in patients with a duration of MV<8 days.
Conclusion: Higher breathing variability and lower complexity are associated with higher survival and lower duration of MV.
Footnotes
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Conflict of interest: Alexandre Demoule reports grants or contracts from Philips, Fisher & Paykel, French Ministry of Health, Respinor, and Lungpacer, outside the submitted work; consulting fees from Lungpacer, and Respinor, outside the submitted work; payment or honoraria from Fisher & Paykel, Getinge, Lungpacer, Gilead, Lowenstein, and Astra, outside the submitted work; support for attending meetings and/or travel from Lungpacer, outside the submitted work.
Conflict of interest: Thomas Similowski reports grants or contracts from Chiesi France, and Air Liquide Medical Systems, outside the submitted work; consulting fees from AstraZeneca France, Boerhinger Ingelheim France, Novartis France, TEVA France, Chiesi France, Lungpacer Inc., and ADEP Assistance, outside the submitted work; payment or honoraria from AstraZeneca France, Boerhinger Ingelheim France, Novartis France, TEVA France, Chiesi France, Lungpacer Inc., and ADEP Assistance, outside the submitted work.
Conflict of interest: The remaining authors have nothing to disclose.
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- Received October 26, 2022.
- Accepted February 9, 2023.
- Copyright ©The authors 2023
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