| dc.description.abstract | Spinal Cord Injury (SCI) results in a variable pathophysiologic profile in which deficits vary with level and degree of injury but can markedly impact both autonomic and respiratory control. Therefore, the SCI population may be especially needful of therapeutic slow-breathing interventions to mitigate the impact of altered autonomic control of the heart and blood vessels and to improve the efficiency of respiration. Therefore, we assessed cardiovascular variabilities during 7 minutes of uncontrolled breathing, controlled breathing at 0.25 Hz and at 0.083 Hz, and ujjayi breathing (0.083 Hz with expiratory resistance via throat constriction) in 12 individuals with SCI from T8 to C4. Beat-to-beat heart rate and blood pressure was measured as well as end-tidal CO2 and oxygen saturation. Compared to uncontrolled breathing, all controlled breathing increased coherence between systolic pressure and RR interval variabilities at the respiratory frequency (0.71 Hz vs >0.85 Hz, p<0.05). The phase relation was shifted by 0.25 Hz breathing to a markedly positive, feedforward relationship (–4° vs +43°, p<0.05), whereas both 0.083 and ujjayi breathing shifted it to a markedly negative, feedback relationship –45° and –44°, p<0.05). Moreover, compared to uncontrolled breathing, 0.25-Hz breathing markedly decreases variabilities at the respiratory frequency in both RR interval and systolic pressure; 0.083-Hz breathing has no effect, whereas ujjayi markedly increases both variabilities (all p<0.05). While 0.25 Hz and 0.083 Hz breathing had variable effects on end tidal CO2 and oxygen saturation, only ujjayi breathing decreases end tidal CO2 and increases oxygen saturation while also resulting in a modest tachycardia (all p<0.05). These findings suggest that slow yogic breathing with respiratory resistance (ujjayi) shifts cardiovascular control to a baroreflex- mediated feedback mechanism and increases both mean heart rate and its variability such that there is improved ventilation-perfusion matching, resulting in increased systemic oxygen saturation. understanding the impact of respiratory changes, such as increased work of breathing, and exploring interventions that can improve respiratory function, cardiovascular control, ventilation-perfusion matching, and oxygen saturation is crucial in the SCI population to manage respiratory complications, enhance respiratory function, and optimize overall health and well-being. | |
