Pulmonary expansion manoeuvres compared to usual care on ventilatory mechanics, oxygenation, length of mechanical ventilation and hospital stay, extubation, atelectasis, and mortality of patients in mechanical ventilation: A randomized clinical trial

Atelectasis is a frequent noninfectious complication in patients on mechanical ventilation, contributing to impaired ventilatory mechanics, ventilation/perfusion mismatch, hypoxemia, and increased risk of infection and prolonged ICU stays. Lung expansion strategies aim to reverse or prevent atelectasis by increasing transpulmonary pressure, either via increased alveolar pressure (e.g., recruitment maneuvers, IPPB, PEEP therapy, ventilator hyperinflation, increased inspiratory time) or by decreasing pleural pressure using manual techniques. Despite widespread clinical use of passive manual manoeuvres such as chest compression-decompression and chest block, there have been no randomized controlled trials in mechanically ventilated adults to support their efficacy. This study addresses that evidence gap by testing whether adding these manual lung expansion techniques to usual care improves static compliance and other clinical and physiologic outcomes in mechanically ventilated ICU patients.

The paper outlines established lung expansion methods using positive pressure (alveolar recruitment, intermittent positive pressure breathing, PEEP therapy, ventilator hyperinflation, increased inspiratory time), which generally have few serious adverse events, with transient hypotension and desaturation being the most common and barotrauma or arrhythmias infrequent. Manual techniques aiming to reduce pleural pressure include compression-decompression and chest block and are commonly employed in resource-limited settings. Prior studies of manual techniques have been largely low-quality (cross-sectional, case reports), lacked control groups, used small convenience samples, and often assessed outcomes not directly relevant to lung expansion. No prior randomized controlled trials had evaluated passive manual manoeuvres in mechanically ventilated adults, motivating the present trial.

Design: Parallel, two-group, randomized controlled trial with concealed allocation (1:1) and intention-to-treat analysis, reported per CONSORT and TIDieR. Trial registered at ReBEC (RBR-7nd6kcb). Ethics approved Nov 12, 2019; written informed consent obtained. Setting and participants: Single tertiary general ICU. Adults (>18 years) on invasive mechanical ventilation for 12–48 hours were eligible. Exclusions: hemodynamic instability (SBP <90 mmHg or MAP <60 mmHg), chest osteoarticular lesions, recent thoracic surgery, pneumothorax, active pulmonary hemorrhage, palliative care, transfer to another hospital, inability to measure outcomes due to ventilator failure, or patient ventilatory effort despite sedation. Randomization and blinding: Random numbers generated by an independent individual (www.randomization.com). Allocation concealed via sequentially numbered, opaque, sealed envelopes opened after enrollment. Participants were sedated (blinded to assessments). Treating physiotherapists and other providers were blinded for all outcomes. The evaluator for follow-up outcomes was blinded to allocation and to ventilatory mechanics/oxygenation outcomes; the evaluator performing ventilatory mechanics/oxygenation measurements was not blinded. Interventions: Both groups received usual care three times daily (~30 min per session): mobilization (passive/active-assisted/active per RASS and MRC grade), expiratory flow acceleration technique, tracheal and upper airway suction via open circuit (80–120 mmHg), and ventilator management (FiO2 not increased to 100% before assessments). The control group received no lung expansion therapy. The intervention group additionally received chest compression-decompression and chest block manoeuvres twice daily after usual care during morning and afternoon sessions throughout the mechanical ventilation period. - Chest compression-decompression: in 30° head-up supine, soft manual bilateral lower costal compression during expiration followed by rapid release at inspiration onset, applied every two ventilatory cycles for 5 minutes total. - Chest block: in 30° head-up supine, sustained manual compression on upper and lower regions of one hemithorax for 5 minutes, then repeated on the contralateral side. Assessments: On the first study day at four time points: A1 (before usual care), A2 (5 min after usual care), A3 (5 min after interventions in intervention group or after a 20-min interval in control), and A4 (30 min after interventions). Follow-up outcomes (atelectasis incidence by daily chest X-ray read by a blinded radiologist, length of ICU and hospital stays, duration of mechanical ventilation, extubation and success, in-hospital mortality) were collected at discharge or death. Outcomes: Primary—static compliance of the respiratory system (ml/cmH2O) = tidal volume/(plateau pressure−total PEEP). Secondary—dynamic compliance, airway resistance, driving pressure, peripheral oxygen saturation (SpO2), atelectasis incidence, duration of mechanical ventilation, extubation and success (success defined as no ventilatory support within 48 h), length of ICU and hospital stay, and in-hospital mortality. Ventilator settings for mechanics: Volume-controlled mode, tidal volume 6 ml/kg predicted body weight, constant inspiratory flow, 3-second inspiratory pause. At least five consistent readings were obtained; waveforms examined for flat plateau. Sample size: Based on prior effect size 0.865 for compliance difference after chest compression-decompression, alpha 0.05, power 0.80, 1:1 allocation; 44 participants required; inflated to 51 for 15% attrition. Statistical analysis: Normality via Kolmogorov-Smirnov/Shapiro-Wilk. Continuous data as mean±SD or median (IQR) as appropriate; categorical as n(%). Repeated measures (static/dynamic compliance, airway resistance, driving pressure, SpO2) compared within/between groups using generalized linear models with baseline as covariate and post hoc minimal significant difference; reported as means with 95% CIs. Follow-up outcomes compared via Mann-Whitney (non-normal) or chi-squared (categorical). Intention-to-treat; two-sided p<0.05 considered significant.

- Participants: 51 randomized (intervention n=25, control n=26); mean age 67.2±14.9 years; 52.9% male. Leading diagnosis: COVID-19 (49%). Most common ventilation mode: volume-controlled (70.6%). - Primary outcome: No significant between-group difference in static compliance before vs after expansion manoeuvres: difference (intervention−control) 3.64 ml/cmH2O (95% CI −0.36 to 7.65), p=0.074; effect size 0.860. - Oxygenation: SpO2 difference favored control; between-group difference (intervention−control) −1.04% (95% CI −1.94 to −0.14), p=0.027 (reported elsewhere as p=0.024). Magnitude deemed clinically negligible. - Other ventilatory mechanics: No significant between-group differences in dynamic compliance, airway resistance, or driving pressure. - Follow-up clinical outcomes (no significant between-group differences): • Incidence of atelectasis: 9/51 (17.6%); control 19.2% vs intervention 16% (p=0.762). • Length of ICU stay (days, median [IQR]): total 15 [9–30]; control 16.5 [9.8–30.3] vs intervention 13 [9–28.5] (p=0.515). • Length of hospital stay (days): total 19 [10–40]; control 18 [9–41.8] vs intervention 19 [10–33] (p=0.977). • Mechanical ventilation time (days): total 11 [7–21]; control 12 [7.5–20.3] vs intervention 11 [6.5–23] (p=0.880). • Extubation performed: 20/51 (39.2%); control 50% vs intervention 28% (p=0.108). • Extubation success: 15/20 (75%) per extubation; control 76.9% vs intervention 71.4% (p=0.787). Per patient: 29.4% overall; control 38.5% vs intervention 20% (p=0.787). • In-hospital mortality: 37/51 (72.5%); control 61.5% vs intervention 84.0% (p=0.072). - No significant harms or unintended effects were observed during or due to the interventions.

Adding chest compression-decompression and chest block manoeuvres to usual care in mechanically ventilated ICU patients did not improve static or dynamic respiratory mechanics, airway resistance, driving pressure, or clinical outcomes. A small statistically significant reduction in SpO2 compared to control was observed in the intervention group, but the magnitude (~1%) is clinically negligible relative to typical desaturation thresholds (≥4% decrease). The lack of improvement in static compliance suggests manual manoeuvres did not sufficiently modulate transpulmonary pressure to recruit collapsed units in this population. Given the widespread use of these manual techniques in clinical practice, the absence of benefit supports re-evaluating their routine use and focusing on evidence-based strategies known to enhance lung expansion and patient outcomes. The trial’s broad inclusion criteria support external validity and applicability to real-world ICU practice.

Compared to usual care, pulmonary expansion manoeuvres (chest compression-decompression and chest block) may not improve the ventilatory mechanics, incidence of atelectasis, oxygenation, time on mechanical ventilation, extubation success, duration of ICU and hospital stays, and in-hospital mortality among individuals on mechanical ventilation. The results of this study can be used to guide evidence-based clinical practice that provide tangible benefits to this population. Further research is needed to confirm the findings of this study.

- The evaluator measuring ventilatory mechanics and oxygenation was not blinded to group allocation. - Potential variability in the execution and duration of the manual manoeuvres due to lack of standardized guidelines and multiple therapists administering interventions, despite training and supervision. - Patients with preexisting atelectasis were not specifically included; the study targeted prevention across all mechanically ventilated patients, which may limit generalizability to those with established atelectasis. - The combined application of chest compression-decompression and chest block prevents attributing effects to individual techniques. - Protocol and analytical adjustments occurred after ethics approval (e.g., recruitment dates, correction of sample size calculation, inclusion of driving pressure outcome, analytical approach), though without changing the interventions.