Atelectasis, a common complication in mechanically ventilated patients, leads to impaired ventilatory mechanics, worsened lung injury, and hypoxemia. Lung expansion strategies aim to prevent or reverse atelectasis by manipulating transpulmonary pressure. While positive pressure ventilation techniques are established, passive manual manoeuvres like compression-decompression and chest block are widely used despite lacking rigorous evidence from randomized controlled trials. This study aimed to address this gap by comparing the effects of these manoeuvres, in addition to usual care, versus usual care alone in mechanically ventilated patients.

Existing literature on lung expansion techniques predominantly focuses on positive pressure ventilation methods, demonstrating effectiveness but also potential adverse effects like barotrauma. While passive manual manoeuvres are frequently employed clinically, especially in resource-constrained settings, the available evidence is limited to smaller studies with methodological weaknesses, such as cross-sectional designs, lack of control groups, and small sample sizes. These studies often lack the rigor needed to definitively establish the efficacy of these techniques in mechanically ventilated patients. The current study, a randomized controlled trial, aims to provide a higher level of evidence to guide clinical practice.

This parallel, two-group, randomized controlled trial (RCT) with concealed allocation (1:1 ratio) and intention-to-treat analysis enrolled adult patients on mechanical ventilation for 12-48 hours. The control group received usual care (passive/active mobilization, airway clearance, tracheal aspiration), while the intervention group received usual care plus chest compression-decompression and chest block manoeuvres twice daily. Assessments (ventilatory mechanics and oxygenation) were conducted at five time points: before usual care (A1), after usual care (A2), after interventions (A3), and 30 minutes post-intervention (A4). The primary outcome was static compliance; secondary outcomes included dynamic compliance, airway resistance, driving pressure, oxygen saturation, atelectasis incidence, mechanical ventilation duration, extubation success, ICU/hospital stay, and mortality. Sample size calculation (G*Power) aimed for 80% power and a 0.05 significance level, adjusting for potential loss to follow-up, resulting in a randomized sample of 51 participants. Data analysis used generalized linear models for within- and between-group comparisons of continuous variables, Mann-Whitney U test and Chi-squared test for secondary outcomes. Blinding was implemented wherever feasible, although the evaluator conducting ventilatory mechanics and oxygenation measurements was not blinded to group assignment.

Fifty-one participants (mean age 67.2 ± 14.9 years, 53% male) were included; 26 in the control and 25 in the intervention group. No significant difference in static compliance was observed between groups before and after manoeuvres [3.64 ml/cmH2O (95% CI: -0.36-7.65), p=0.074]. Peripheral oxygen saturation differed significantly between groups, with the control group exhibiting more favorable results [-1.04% (95% CI: -1.94 – -0.14), p=0.027]. This difference was considered clinically insignificant. No significant between-group differences were found in other secondary outcomes: dynamic compliance, airway resistance, driving pressure, atelectasis incidence (19% control vs. 16% intervention), length of ICU/hospital stay (15 vs 13 days and 19 vs 19 days, respectively), duration of mechanical ventilation (11 vs 11 days), extubation success (77% vs 71%), or in-hospital mortality (62% vs 84%). An informal survey indicated that the manual manoeuvres studied are widely used in clinical practice in Brazil.

This study challenges the widespread clinical use of chest compression-decompression and chest block manoeuvres in mechanically ventilated patients. The lack of significant improvement in ventilatory mechanics and even a slight negative impact on oxygen saturation, despite being clinically insignificant, do not support their efficacy. The results highlight the need for evidence-based practice and suggest that resources might be better allocated to other interventions with proven benefits. The high rate of in-hospital mortality (72.5%) underscores the need for further research to optimize care for this critically ill population.

This RCT provides strong evidence that the addition of chest compression-decompression and chest block manoeuvres to usual care does not improve outcomes in mechanically ventilated patients. These findings necessitate a reassessment of current clinical practice and underscore the need for evidence-based decision-making in the management of critically ill patients. Future research should focus on identifying alternative strategies or refining the techniques studied, potentially examining the effectiveness of each technique separately and in patients with pre-existing atelectasis.

The study's limitations include the lack of blinding for the evaluator performing ventilatory mechanics and oxygenation measurements, potential variability in manoeuvre execution due to multiple therapists, the absence of patients with pre-existing atelectasis in the study population, and the inability to isolate the effect of each individual manoeuvre. The use of a single center may limit generalizability.