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. 2025 Aug 5;13(1):78.
doi: 10.1186/s40635-025-00788-y.

Comparative evaluation of spontaneous breathing trial techniques for ventilator weaning: a bench study

Guillaume Fossat  1   2 , Roberto Martínez Alejos  3   4   5 , Emeline Fresnel  3 , Mai-Anh Nay  6 , Clément Medrinal  7   8 , Marius Lebret  3   9
Affiliations

Comparative evaluation of spontaneous breathing trial techniques for ventilator weaning: a bench study

Guillaume Fossat et al. Intensive Care Med Exp. .

Abstract

Background: Spontaneous breathing trials (SBT) are crucial for determining when mechanically ventilated patients are ready for extubation. While pressure support (PS) and T-piece trials are commonly used, humidified high-flow (HHF) is increasingly considered, but its physiological effects remain unclear. This bench study compares T-piece, PS, and HHF modalities, evaluating their impact on work of breathing (WOB), tidal volume (Vt), total positive end-expiratory pressure (PEEPtot) and CO2 clearance.

Methods: A 3D-printed manikin head connected to an artificial lung was used. Four SBT modalities were tested: T-piece with and without supplemental oxygen, PS at 7 cmH2O (PEEP 0 cmH2O), and HHF at 50 L/min. The tests were performed under three lung conditions (normal, obstructive, restrictive) and two respiratory drive and effort settings (normal and intense), resulting in 24 scenarios. Measurements included WOB, CO2 clearance, PEEPtot, and Vt.

Results: T-piece and HHF50 SBTs exhibited similar effects on WOB, irrespective of the effort pattern associated with the underlying respiratory mechanics. For intense effort patterns, the CO2 concentration was lower with HHF than with PS, regardless of respiratory mechanics. The HHF50 SBT increased PEEPtot more than T-piece SBTs, but less than PS SBT, for all scenarios. HHF50 SBT generated lower tidal volume than T-piece and PS SBTs.

Conclusions: Humidified high-flow at 50 L/min, while preserving WOB and not increasing tidal volume, may offer specific advantages, such as improved CO2 clearance and PEEP effect, and could be considered as a trade-off for T-piece or PS SBTs.

Keywords: Dead space washout; High flow; ICU; Spontaneous breathing trial; Weaning; Work of breathing.

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Conflict of interest statement

Declarations. Ethics approval and consent to participate: Not applicable. Consent for publication: Not applicable. Competing interests: GF and MAN received reimbursements and fees as consultants from Fisher & Paykel Healthcare, Auckland, New Zealand. ML is part-time employee of ALMS in a non-commercial role.

Figures

Fig. 1
Fig. 1
Experimental bench model and SBT conditions. Blue points indicate locations of measures. SBT spontaneous breathing trial, LPM liters per minute, PEEP positive end-expiratory pressure, PS pressure support, CO2 carbon dioxide, AGEC protective balloon
Fig. 2
Fig. 2
Work of breathing according to each spontaneous breathing trial scenario. * indicates statistical significance difference (p < 0.001) using Kruskal–Wallis tests and pairwise comparison using Dunn’s post hoc tests. Median absolute values and interquartile range are presented in Table S3. WOB work of breathing, J L−1 Joule per liter, cmH2O centimeter of water, PS pressure support, HHF50 humidified high-flow at 50 L/min, NS non-significant
Fig. 3
Fig. 3
CO2 concentration at the end of each spontaneous breathing trial scenario. * indicates statistical significance difference (p < 0.001) using Kruskal–Wallis tests and pairwise comparison using Dunn’s post hoc tests. Median absolute values and interquartile range are presented in Table S4. ppm part per million, cmH2O centimeter of water, PS pressure support, HHF50 humidified high-flow at 50 L/min
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