Autonomic Dysreflexia in Spinal Cord Injury: Its Role in Altering Skin Perfusion and Oxygenation

Abstract

Autonomic dysreflexia (AD) is a condition unique to people with spinal cord injury (SCI) at and cephalic to T6. In these individuals, a noxious stimulus may cause a predominant sympathetic response of the autonomic nervous system characterized by extreme elevations in blood pressure, headache, vision changes, facial flushing, and sweating above the level of injury. In this study, we aimed to describe the tissue changes that occur in skin during an episode of AD. Because of the severe vasoconstriction that occurs with AD, we hypothesized that even minor episodes can lead to other problems, such as tissue ischemia. We describe the development and preliminary testing of a fiber optic–based system, which can be used to quantitatively and noninvasively assess skin changes, including oxygen levels, blood flow, and blood volume fraction, during normal rest and during an AD event. Seven subjects with tetraplegia and a history of AD were assessed. AD was induced by filling the subjects’ bladders with saline. Systolic and diastolic blood pressure was monitored, and the subjects provided continual feedback as to AD symptoms. Six of the 7 individuals developed AD. All individuals who developed AD also showed a reduction in blood volume fraction below the level of injury. Five individuals also showed a reduction in superficial skin oxygenation, and 4 demonstrated a reduction in skin perfusion. In this small pilot study on 7 individuals with SCI, we demonstrate that AD is associated with changes in superficial skin hemodynamics. As this fiber optic system is further developed, these preliminary findings could impact preventive recommendations for pressure ulcer prevention in people with SCI.