Expiratory Rib Cage Compression in Mechanically Ventilated Subjects: A Randomized Crossover Trial

BACKGROUND: Expiratory rib cage compression (ERCC) has been empirically used by physiotherapists with the rationale of improving expiratory flows and therefore the airway clearance in mechanically ventilated patients. This study evaluates 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 subjects submitted to 2 interventions. ERCC intervention consisted of a series of manual bilateral ERCCs, followed by a hyperinflation maneuver. Control intervention (CTRL) followed the same sequence, but instead of the compressive maneuver, the subjects were kept on normal ventilation. Static (C-st) and effective (C-eff) compliance and total (R-tot) and initial (R-init) resistance of the respiratory system were measured pre-ERCC (baseline), post-ERCC or CTRL (POST I), and post-hyperinflation (POST2). Peak expiratory flow (PEF) and the flow at 30% of the expiratory tidal volume (flow 30% V-T) were measured during the maneuver. RESULTS: ERCC cleared 34.4% more secretions than CTRL (1 [0.5-1.95] vs 2 [1-3.25], P < .01). Respiratory mechanics showed no differences between control and experimental intervention in POST] for C-st, C-eff, R-tot, and R-init. In POST2, ERCC promoted an increase in C-st (38.7 +/- 10.3 vs 42.2 +/- 12 mL/cm H2O, P = .03) and in C-eff (32.6 +/- 9.1 vs 34.8 +/- 9.4 mL/cm H2O, P = .04). During ERCC, PEF increased by 16.2 L/min (P < .001), and flow 30% V-T increased by 25.3 L/min (P < .001) compared with CTRL. Six subjects (30%) presented expiratory flow limitation (EFL) during ERCC. The effect size was small for secretion volume (0.2), C-st (0.15), and C-eff (0.12) and negligible for R-tot (0.04) and R-init (0.04). CONCLUSIONS: Although ERCC increases expiratory flow, it has no clinically relevant effects from improving the sputum production and respiratory mechanics in hypersecretive mechanically ventilated patients. The maneuver can cause EFL in some patients.