Cognition may be related to arterial pulsatility index in HD patients.

AIMS: Hemodialysis (HD) patients have a heavy burden of subclinical cerebrovascular disease and cognitive changes consistent with a vascular etiology. Pulsatility index is associated with microangiopathy of cerebral blood vessels and an increased risk of cerebral infarction. The proposed study was to determine common carotid artery pulsatility index (CCAPI) and its relation to cognition in well-dialyzed HD patients with no history of stroke or dementia and matched controls. METHODS: Observational, cross-sectional study of CCAPI and cognition in 37 hemodialysis outpatients and 18 matched controls with normal kidney function. Non-parametric analyses were used to compare variables between groups. Multiple regression and ANOVA models were used to adjust for risk factor differences. RESULTS: Controls had a lower CCAPI than the HD group (1.7 ± 0.3 vs. 2.1 ± 0.4 cm/s, p = 0.006). HD patients scored significantly lower on all cognitive domains. Attention correlated with CCAPI in HD patients, independent of hypertension, diabetes, hyperlipidemia, and years on HD (r2 = -0.36, p = 0.01). CCAPI correlated with years on HD, independent of traditional cardiovascular risk factors. (r2 = 0.26, p = 0.04). CONCLUSION: In well-dialyzed hemodialysis patients with no history of stroke or dementia, CCAPI may correlate with cognitive function and represent a marker for underlying cerebral microvascular disease.

The hemodynamic actions of insulin are blunted in the sublesional microvasculature of healthy persons with spinal cord injury.

OBJECTIVE: The aim of this study was to gain a better understanding of the hemodynamic actions of insulin on cutaneous microcirculation in persons with spinal cord injury (SCI). DESIGN: A prospective, open-label, nonrandomized, placebo-controlled investigation was performed in an otherwise healthy cohort of persons with SCI (n = 10) and in an age- and sex-matched cohort of control subjects whose neurologic function is intact (n = 10). Laser Doppler flowmetry characterized the peak blood perfusion unit (BPU) response (percent change from baseline) to insulin or placebo iontophoresis above and below the neurologic level of injury. RESULTS: Placebo iontophoresis did not result in any statistically significant changes in BPU. In the arm, insulin iontophoresis resulted in a 20% mean increase in BPU (P < 0.05) in the control group and a 9% mean increase in the SCI group (P = 0.14). In the leg, insulin iontophoresis resulted in an 81% (P < 0.01) mean increase in BPU in the control group and a 29% (P < 0.001) mean increase in BPU in the SCI group. The relative effect of insulin on the lower extremity BPU response was significantly greater (P < 0.05) in the control group compared with the SCI group (77% vs. 35%, respectively). CONCLUSIONS: The hemodynamic actions of insulin are markedly blunted in the sublesional microvasculature of persons with SCI, most likely as a result of impaired sublesional sympathetic nervous system control.