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Functional Magnetic Stimulation of Inspiratory and Expiratory Muscles in Subjects With Tetraplegia
Author(s) -
Zhang Xiaoming,
Plow Ela,
Ranganthan Vinoth,
Huang Honglian,
Schmitt Melissa,
Nemunaitis Gregory,
Kelly Clay,
Frost Frederick,
Lin Ver
Publication year - 2016
Publication title -
pmandr
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.617
H-Index - 66
eISSN - 1934-1563
pISSN - 1934-1482
DOI - 10.1016/j.pmrj.2016.01.016
Subject(s) - medicine , tetraplegia , anesthesia , ventilation (architecture) , spinal cord injury , cardiology , spinal cord , mechanical engineering , psychiatry , engineering
Background Respiratory complications are major causes of morbidity and mortality in persons with a spinal cord injury, partly because of respiratory muscle paralysis. Earlier investigation has demonstrated that functional magnetic stimulation (FMS) can be used as a noninvasive technology for activating expiratory muscles, thus producing useful expiratory functions (simulated cough) in subjects with spinal cord injury. Objective To evaluate the effectiveness of FMS for conditioning inspiratory and expiratory muscles in persons with tetraplegia. Design A prospective before and after trial. Setting FMS Laboratory, Louis Stokes Cleveland VA Medical Center, Cleveland, OH. Participants Six persons with tetraplegia. Method Each subject participated in a 6‐week FMS protocol for conditioning the inspiratory and expiratory muscles. A magnetic stimulator was used with the center of a magnetic coil placed at the C7‐T1 and T9‐T10 spinous processes, respectively. Pulmonary function tests were performed before, during, and after the protocol. Main Outcome Measurements Respiratory variables included maximal inspiratory pressure (MIP), inspiratory reserve volume (IRV), peak inspiratory flow (PIF), maximal expiratory pressure (MEP), expiratory reserve volume (ERV), and peak expiratory flow (PEF). Results After 6 weeks of conditioning, the main outcome measurements (mean ± standard error) were as follows: MIP, 89.6 ± 7.3 cm H 2 O; IRV, 1.90 ± 0.34 L; PIF, 302.4 ± 36.3 L/min; MEP, 67.4 ± 11.1 cm H 2 O; ERV, 0.40 ± 0.06 L; and PEF, 372.4 ± 31.9 L/min. These values corresponded to 117%, 107%, 136%, 109%, 130%, and 124% of pre‐FMS conditioning values, respectively. Significant improvements were observed in MIP ( P = .022), PIF ( P = .0001), and PEF ( P = .0006), respectively. When FMS was discontinued for 4 weeks, these values showed decreases from their values at the end of the conditioning protocol, which suggests that continual FMS may be necessary to maintain improved respiratory functions. Conclusion FMS conditioning of the inspiratory and expiratory muscles improved voluntary inspiratory and expiratory functions. FMS may be a noninvasive technology for respiratory muscle training in persons with tetraplegia.