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. 2025 Sep 16;14(18):6516.
doi: 10.3390/jcm14186516.

Expiratory Flow Bias and Physiological Effects of Rapid Chest Compression in Mechanically Ventilated Neurocritical Patients: A Secondary Analysis of a Randomized Controlled Trial

Ricardo Miguel Rodrigues-Gomes  1   2 , Rosa Martinez Rolán  3 , Maribel Botana-Rial  4   5 , Alejandra Del Río González  6 , Eduardo Arán-Echabe  7   8
Affiliations

Expiratory Flow Bias and Physiological Effects of Rapid Chest Compression in Mechanically Ventilated Neurocritical Patients: A Secondary Analysis of a Randomized Controlled Trial

Ricardo Miguel Rodrigues-Gomes et al. J Clin Med. .

Abstract

Background: Mechanical ventilation compromises airway clearance, with expiratory flow bias (EFB) being a critical determinant of mucus transport. The rapid chest compression technique (RCCT) generates high EFB, yet evidence in neurocritical patients is limited due to concerns regarding intracranial pressure (ICP). This secondary analysis of a randomized controlled trial examined the effects of RCCT on ventilatory mechanics and physiology in acute brain-injured patients under invasive ventilation. Methods: Fifty neurocritical patients were randomized to RCCT (Intervention) or passive leg mobilization (Control). RCCT was applied bilaterally during expiration once every three respiratory cycles for 5 min; controls underwent 5 min of passive cycling. EFB, derived from inspiratory and expiratory peak flows, was assessed at baseline (T-5), during intervention (T0-T5), and post-intervention (T+5, T+30). Arterial blood gases, mean arterial pressure (MAP), heart rate (HR), and ICP were also analyzed. Group comparisons used parametric/non-parametric tests; associations were explored via Spearman's rho. Results: Baseline EFB did not differ between groups. From T0 to T5, Intervention patients showed significantly higher EFB (all p < 0.001). PaCO2 decreased within the Intervention group (p = 0.015) but not in controls (p = 0.601). No between-group ΔPaCO2 differences emerged. At T5, HR correlated negatively with EFB (ρ = -0.49, p = 0.013). No associations were found with age, sex, lesion type, MAP, or ICP. Conclusions: RCCT effectively increased EFB in ventilated neurocritical patients without affecting ICP, supporting its safety and potential role in airway clearance.

Keywords: airway clearance techniques; expiratory flow bias; intracranial pressure; mechanical ventilation; respiratory physiotherapy.

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Conflict of interest statement

The authors declare no conflicts of interest.

Figures

Figure 1
Figure 1
CONSORT flow chart.
Figure 2
Figure 2
Mean expiratory flow bias at each time point.
Figure 3
Figure 3
Correlation between expiratory flow bias at T5 and PaCO2 changes.
Figure 4
Figure 4
Expiratory flow bias at each time point in the intervention group, stratified by sex.
Figure 5
Figure 5
Relationship between age and expiratory flow bias at time point T5 in both study groups.
Figure 6
Figure 6
Correlation between heart rate and expiratory flow bias at T5 in the intervention group. Blue crosses represent individual patients, and the dashed line indicates the regression line.
Figure 7
Figure 7
Correlation between respiratory rate and expiratory flow bias at T5 in the intervention group. Blue crosses represent individual patients, the dashed line indicates the regression line, and the shaded area corresponds to the 95% confidence interval.
See this image and copyright information in PMC

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