Acute Ventilatory Support During Whole-Body Hybrid Rowing in Patients With High-Level Spinal Cord Injury A Randomized Controlled Crossover Trial

BACKGROUND: High-level spinal cord injury (SCI) results in profound spinal and supraspinal deficits, leading to substantial ventilatory limitations during whole-body hybrid functional electrical stimulation (FES)-rowing, a form of exercise that markedly increases the active muscle mass via electrically induced leg contractions. This study tested the effect of noninvasive ventilation (NIV) on ventilatory and aerobic capacities in SCI. METHODS: This blinded, randomized crossover study enrolled 19 patients with SCI (level of injury ranging from C4 to T8). All patients were familiar with FES-rowing and had plateaued in their training-related increases in aerobic capacity. Patients performed two FES-rowing peak exercise tests with NIV or without NIV (sham). RESULTS: NIV increased exercise tidal volume (peak, 1.50 +/- 0.31 L vs 1.36 +/- 0.34 L; P < .05) and reduced breathing frequency (peak, 35 +/- 7 beats/min vs 38 +/- 6 beats/min; P < .05) compared with the sham test, leading to no change in alveolar ventilation but a trend toward increased oxygen uptake efficiency (P = .06). In those who reached peak oxygen consumption (VO(2)peak) criteria (n = 13), NIV failed to significantly increase VO(2)peak (1.73 +/- 0.66 L/min vs 1.78 +/- 0.59 L/min); however, the range of responses revealed a correlation between changes in peak alveolar ventilation and VO(2)peak (r = 0.89; P < .05). Furthermore, those with higher level injuries and shorter time since injury exhibited the greatest increases in VO(2)peak. CONCLUSIONS: Acute NIV can successfully improve ventilatory efficiency during FES exercise in SCI but may not improve VO(2)peak in all patients. Those who benefit most seem to be patients with cervical SCI within a shorter time since injury.