Effects of Respiratory Training on Heart Rate Variability and Baroreflex Sensitivity in Individuals with Chronic Spinal Cord Injury

Publication date: Available online 9 August 2017
Source:Archives of Physical Medicine and Rehabilitation
Author(s): Bonnie E. Legg Ditterline, Sevda C. Aslan, David C. Randall, Susan J. Harkema, Camilo Castillo, Alexander V. Ovechkin
ObjectiveTo evaluate the effects of pressure threshold respiratory training (RT) on heart rate variability and baroreflex sensitivity in persons with chronic spinal cord injury (SCI).DesignBefore-after intervention case-controlled clinical study.SettingSCI research center and outpatient rehabilitation unit.ParticipantsPersons with chronic SCI ranging from C2 to T11 that participated in RT (n=24) and untrained chronic SCI controls ranging from C2 to T9 (n=20).InterventionA total of 21 ± 2 of RT sessions performed 5 days a week during a four-week period using a combination of pressure threshold inspiratory and expiratory devices.Main Outcome MeasuresForced vital capacity (FVC), forced expiratory volume in one second (FEV1), and beat-to-beat arterial blood pressure (BP) and heart rate (HR) changes during 5-second long maximum expiratory pressure maneuver (5s MEP) and sit-up orthostatic stress test acquired before and after the RT program.ResultsIn contrast to the untrained controls, individuals in RT group experienced significantly increased FVC and FEV1 (both p < .01) in association with improved quality of sleep, cough, and speech. Sympathetically (phase II) and parasympathetically (phase IV) mediated baroreflex sensitivity both significantly (p < .05) increased during 5s MEP. During orthostatic stress test, improved autonomic control over HR was associated with significantly increased sympathetic and parasympathetic modulation (low- and high-frequency change, p < .01 and p < .05, respectively).ConclusionThe results indicate that inspiratory-expiratory pressure threshold RT is a promising technique to positively impact both respiratory and cardiovascular dysregulation observed in persons with chronic SCI.



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