Inspiratory muscle training for diaphragm dysfunction after cardiac surgery

OBJECTIVE: Diaphragm dysfunction is a complication of cardiac surgery with partial or absent spontaneous recovery in most cases. Surgical diaphragm plication represents the only option when symptoms persist. Because training improves functional nerve recovery after a nerve lesion, we hypothesized that early diaphragm muscle training may be beneficial. METHODS: A prospective, randomized at 2:1 ratio, controlled trial of diaphragm training using an adjustable pressure device (Threshold; Philips Respironics Inc, Murrysville, Pa) versus no training (sham device) was performed in patients with diaphragm paralysis after major cardiac surgery. This 1-year study recruited consecutive adult patients with sniff fluoroscopy-defined diaphragm paralysis after coronary bypass, valve replacement, or both. The outcome measures were diaphragm function recovery assessed by sniff fluoroscopy, maximum inspiratory and expiratory pressures, and lung function tests. RESULTS: A total of 69 patients were randomized. At 12 months, 52 patients completed the study assessments, 36 in the treatment group and 16 in the control group. Inspiratory muscle training produced a significant improvement of diaphragm mobility after 12 months (P < .001). Most patients in the training group (77.78%) experienced a partial improvement (41.67%) or achieved a complete improvement (36.11%) versus no improvement (87.5%) or partial recovery (12.5%) among controls. CONCLUSIONS: Inspiratory muscle training may improve inspiratory muscle strength and increases paralyzed diaphragm mobility.