Respiratory muscle endurance training with normocapnic hyperpnoea for patients with chronic spinal cord injury: A pilot short-term randomized controlled trial

Objective: To investigate the effects of normocapnic hyperpnoea training on pulmonary function and patient-reported outcomes in chronic spinal cord injury.

Design: Single-centre randomized controlled trial.

Patients: Eighteen patients with spinal cord injury > 24 months post-injury and without regular respiratory muscle training prior to the study were included prospectively.

Methods: Patients were randomly assigned to either normocapnic hyperpnoea or control groups. The normocapnic hyperpnoea group patients performed training 15-20 min per day, 5 times a week for 4 weeks. The patients hyperventilated through partial re-breathing of ventilated air. The control group received no respiratory muscle training. Other rehabilitative programmes were performed identically in both groups. Lung function testing was performed in the sitting position prior to and after the study. Patient-reported outcomes were assessed using the Patient Health Questionnaire-9, St George's Respiratory Questionnaire, Chronic Obstructive Pulmonary Disease Assessment Test and Borg scores.

Results: Significant differences were found in the improvement ratio between the normocapnic hyperpnoea and control groups for all investigated parameters, except total lung capacity and diffusing capacity of the lung for carbon monoxide.

Conclusion: Normocapnic hyperpnoea training may reduce the incidence of respiratory symptoms, improve pulmonary function and quality of life, and reduce depression in patients with chronic spinal cord injury, regardless of their neurological level of injury, even at more than 24 months after injury.