Cardiovascular control in the human is significantly impaired after spinal cord injury(SCI) having a direct effect on the sympathetic nervous system (SNS) causing an inability toregulate vasoconstriction below the level of the lesion. The effects of SCI on the two majorcomponents of blood pressure regulation, control of plasma volume and neural control of theheart and peripheral vasculature are poorly understood. In particular, no index to diagnosedisorders to autonomic control of the heart and vasculature has been developed. The presentstudy primarily utilized noninvasively acquired, easily accessible variables that may havepromise as indicators of autonomic activity for assessing the level of autonomic injury andrecovery of visceral control following SCI. The most significant results and the clearestdifferences between the three groups (able-bodied, paraplegic and tetraplegic) were evident inspectral analysis obtained in the frequency domain: Arterial blood pressure and lower body (at aregion on the shin) skin perfusion spectral power in the low frequency (LF) region are ofsignificance. These variables could be good discriminators of the three groups, as well as showlevel of SCI and autonomic function.

Context: Low current intensity iontophoresis treatments have shown an increase in skin perfusion over 700% from baseline potentially increasing drug clearance from the targeted area. Objective: To determine the effects of a 10-minute ice massage on subcutaneous dexamethasone sodium phosphate (Dex-P) concentration and skin perfusion during and after a 4 mA iontophoresis treatment. Design: Controlled laboratory study. Setting: Research Laboratory. Patients or Other Participants: 26 individual participants (Males = 15, Females = 11, age = 25.6 ± 4.5 y, height = 173.9 ± 8.51 cm, mass = 76.11 ± 16.84 kg). Interventions: Participants were randomly assigned into two groups: 1) Pretreatment 10-minute ice massage; and 2) no pretreatment ice massage. Treatment consisted of an 80 mA min (4 mA∙20 minutes) Dex-P iontophoresis treatment. Microdialysis probes (3 mm deep in the forearm) were used to assess Dex-P, dexamethasone (Dex), and its metabolite (Dex-met) concentrations. Skin perfusion was measured using laser Doppler flowmetry probes. Main Outcome Measures: Microdialysis samples were collected at baseline, at conclusion of treatment, and every 20 minutes posttreatment for 60 minutes. Samples were analyzed to determine Dex-total concentration ([Dex-total] = Dex-P + Dex + Dex-met). Skin perfusion was calculated as a percent change from baseline. A repeated measures ANOVA was used for Dex-total and Skin Perfusion. Results: No significant difference was found in [Dex-total] between ice and no ice treatments, (P = 0.265). A significant increase in [Dex-total] occurred over the course of the iontophoresis and posttreatment time (P <<> 0.0004). Dex-P was recovered in 15 of 21 participants with a mean concentration of 0.604 ± 0.843 g/mL. Peak skin perfusion reached 27.74 ± 47.49% and 117.39 ± 103.45% from baseline for the ice and nonice groups, respectively. Conclusions: The 10-minute ice massage prior to iontophoresis does not significantly alter the delivery of [Dex-total] through the skin. A greater [Dex-P] was recovered than previously seen with lower intensities.