Critical Care volume 29,
Article number: 19 (2025)
Published: 10 January 2025
Background
Double cycling with breath-stacking (DC/BS) during
controlled mechanical ventilation is considered potentially injurious,
reflecting a high respiratory drive. During partial ventilatory support, its
occurrence might be attributable to physiological variability of breathing
patterns, reflecting the response of the mode without carrying specific risks.
Methods
This secondary analysis of a crossover study evaluated DC/BS
events in hypoxemic patients resuming spontaneous breathing in cross-over under
neurally adjusted ventilatory assist (NAVA), proportional assist ventilation
(PAV +), and pressure
support ventilation (PSV). DC/BS was defined as two inspiratory cycles with
incomplete exhalation. Measurements included electrical impedance signal,
airway pressure, esophageal and gastric pressures, and flow. Breathing
variability, dynamic compliance (CLdyn), and end-expiratory lung impedance
(EELI) were analyzed.
Results
Twenty patients under assisted breathing, with a median of 9
[5–14] days on mechanical ventilation, were included. DC/BS was attributed to
either a single (42%) or two apparent consecutive inspiratory efforts (58%).
The median [IQR] incidence of DC/BS was low: 0.6 [0.1–2.6] % in NAVA, 0.0
[0.0–0.4] % in PAV + , and 0.1 [0.0–0.4] % in PSV (p = 0.06). DC/BS events were
associated with patient’s coefficient of variability for
tidal volume (p = 0.014) and respiratory rate (p = 0.011).
DC/BS breaths exhibited higher tidal volume, muscular pressure and regional
stretch compared to regular breaths. Post-DC/BS cycles frequently exhibited
improved EELI and CLdyn, with no evidence of expiratory muscle activation in
63% of cases.
Conclusions
DC/BS events during partial ventilatory support were
infrequent and linked to breathing variability. Their frequency and
physiological effects on lung compliance and EELI resemble spontaneous sighs
and may not be considered a priori as harmful.
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