Date on Master's Thesis/Doctoral Dissertation

12-2015

Document Type

Doctoral Dissertation

Degree Name

Ph. D.

Department

Physiology and Biophysics

Degree Program

Physiology and Biophysics, PhD

Committee Chair

Ovechkin, Alexander

Committee Co-Chair (if applicable)

Schuschke, Dale

Committee Member

Schuschke, Dale

Committee Member

Joshua, Irving

Committee Member

Maldonado, Claudio

Committee Member

Swank, Ann

Author's Keywords

spinal cord injury; baroreceptor reflex; cardiopulmonary reflex; respiratory training; cardiovascular function

Abstract

This dissertation attempts to discover the mechanisms between cardiovascular and respiratory motor control post spinal cord injury (SCI): in normal, non-injured (NI) persons, cardiovascular regulation is dependent upon respiration, but there is nothing that suggests the mechanism for this relationship post-SCI. Thus we hoped to evaluate various aspects of cardiovascular regulation to further illustrate how this relationship is changed or unchanged by SCI. Chapter I describes the anatomy and physiology of the spine, respiratory system, and cardiovascular system in a NI person, and then describes how the function of these systems is changed by SCI. In addition, we describe therapies available to persons with SCI to treat or manage these dysfunctions. Briefly, cardiovascular function is dependent on respiration, and motor and sensory activity is partially mediated by the spine. Thus, SCI will impair respiratory and cardiovascular function because neurons from these respective systems originate within the spine. In addition to that, we hypothesize that SCI will further impair reflexes due to the dependence of cardiovascular regulation on respiration. This relationship has not been studied post-SCI, but it has great therapeutic potential. Chapter II details our specific aims and respective hypotheses: we think that poor respiration will exacerbate cardiovascular dysfunction (one) such that level and completeness will not correlate to cardiovascular functional outcomes (two); if hypotheses one and two are correct, then we hypothesize that we will be able to improve cardiovascular regulation by improving respiratory motor control. In Chapter III, we describe the methods and protocol by which we will either confirm or refute our respective hypotheses, including pulmonary and cardiovascular assessments, and statistical methods. Chapters IV, V, VI, and VII include our results and subsequent discussions, including validation of a particular method (Chapter IV); confirmation of cardiovascular impairment secondary to poor respiratory motor control (Chapter V); subsequent independence of functional outcomes and level of injury (Chapter VI); and improvements to cardiovascular regulation following improved respiratory motor control (Chapter VII). Finally, in Chapter VIII, we conclude that there is still dependence of cardiovascular function on respiration post-SCI, and describe the potential benefits that respiratory motor training can have on this population. In addition, we detail future directions as we pursue our goal of developing respiratory motor training into a standard of care in persons with SCI.

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