Expiratory Rib Cage Compression, Secretion Clearance and Respiratory Mechanics in Mechanically Ventilated Patients: A Randomized Crossover Trial

Background Expiratory rib cage compression (ERCC) has been empirically used by the physiotherapists with the rationale of improving expiratory flows and, therefore, the airway clearance in mechanically ventilated patients. This study aimed at evaluating the acute mechanical effects and sputum clearance of an ERCC protocol in ventilated patients with pulmonary infection.

Methods In a randomized crossover study, sputum production and respiratory mechanics were evaluated in 20 mechanically ventilated patients submitted to 2 interventions. Expiratory rib cage compression intervention consisted of a series of manual bilateral expiratory rib-cage compressions followed by a hyperinflation maneuver. Control intervention (CTRL) followed the same sequence, but instead of the compressive maneuver, the patients were kept on normal ventilation. Static (Cst) and effective (Ceff) compliance, and total (Rtot) and initial (Rinit) resistance of the respiratory system were measured pre (baseline), post-ERCC or CTRL (POST1), and post-hyperinflation (POST2). Peak expiratory flow (PEF) and the flow at 30% of the expiratory tidal volume (Flow 30%Vt) were measured during the maneuver.

Results Expiratory rib cage compression cleared 34.4% more secretions than CTRL (2.24±1.59 vs 1.47±1.45mL; P=.04). Respiratory mechanics showed no differences between control and experimental intervention in POST1 for Cst, Ceff, Rtot and Rinit. In POST2 ERCC promoted an increase in Cst (38.7±10.3 vs 42.2 ±12mL/cmH2O; P=.025) and in Ceff (32.6±9.1 vs 34.8±9.4mL/cmH2O; P=.044). During ERCC, PEF increased 16.2L/min P<.001) and Flow 30%Vt increased 25.3L/min (P<.001) when compared with CTRL. Six patients (30%) presented expiratory flow limitation during ERCC. The effect size was small for secretion volume (0.2), Cst (0.15) and Ceff (0.12), and negligible for Rtot (0.04) and Rinit (0.04).

Conclusions Although ERCC increases expiratory flow, it has no clinically relevant effects in improving the sputum production and respiratory mechanics in hypersecretive mechanically ventilated patients. The maneuver can cause expiratory flow limitation in some patients.

Trial registration NCT01525121