Dynamic cerebral autoregulation after intracerebral hemorrhage: A case-control study

<p>Abstract</p> <p>Background</p> <p>Dynamic cerebral autoregulation after intracerebral hemorrhage (ICH) remains poorly understood. We performed a case-control study to compare dynamic autoregulation between ICH patients and healthy controls.</p> <p>Methods</p> <p>Twenty-one patients (66 ± 15 years) with early (< 72 hours) lobar or basal ganglia ICH were prospectively studied and compared to twenty-three age-matched controls (65 ± 9 years). Continuous measures of mean flow velocity (MFV) in the middle cerebral artery and mean arterial blood pressure (MAP) were obtained over 5 min. Cerebrovascular resistance index (CVR_i) was calculated as the ratio of MAP to MFV. Dynamic cerebral autoregulation was assessed using transfer function analysis of spontaneous MAP and MFV oscillations in the low (0.03-0.15 Hz) and high (0.15-0.5 Hz) frequency ranges.</p> <p>Results</p> <p>The ICH group demonstrated higher CVR_icompared to controls (ipsilateral: 1.91 ± 1.01 mmHg·s·cm^-1, <it>p </it>= 0.04; contralateral: 2.01 ± 1.24 mmHg·s·cm^-1, <it>p </it>= 0.04; vs. control: 1.42 ± 0.45 mmHg·s·cm^-1). The ICH group had higher gains than controls in the low (ipsilateral: 1.33 ± 0.58%/mmHg, <it>p </it>= 0.0005; contralateral: 1.47 ± 0.98%/mmHg, <it>p </it>= 0.004; vs. control: 0.82 ± 0.30%/mmHg) and high (ipsilateral: 2.11 ± 1.31%/mmHg, <it>p </it>< 0.0001; contralateral: 2.14 ± 1.49%/mmHg, <it>p </it>< 0.0001; vs. control: 0.66 ± 0.26%/mmHg) frequency ranges. The ICH group also had higher coherence in the contralateral hemisphere than the control (ICH contralateral: 0.53 ± 0.38, <it>p </it>= 0.02; vs. control: 0.38 ± 0.15) in the high frequency range.</p> <p>Conclusions</p> <p>Patients with ICH had higher gains in a wide range of frequency ranges compared to controls. These findings suggest that dynamic cerebral autoregulation may be less effective in the early days after ICH. Further study is needed to determine the relationship between hematoma size and severity of autoregulation impairment.</p

Increasing blood pressure variability predicts poor functional outcome following acute stroke

Introduction: Increasing blood pressure variability has been reported following acute stroke, but there is uncertainty about how best to measure it and about the impact on prognosis following acute ischaemic stroke and transient ischaemic attack. Methods: Enhanced casual blood pressure and ambulatory blood pressure monitoring were completed at baseline (≤48 hours post symptom onset). Blood pressure variability was defined by standard deviation and coefficient of variation of systolic, diastolic, mean arterial pressure, and pulse pressure. Modified Rankin scale score ≥3 described poor functional outcome assessed at 1- and 12-months post-stroke. Multivariable logistic regression models incorporating blood pressure variability measurement and other factors were performed, and odds ratio and 95% confidence intervals reported. Results: 232 patients were recruited; 45 were dependent at 1-month, and 37 at 12-months. Dependent patients were more likely to be older, with a higher burden of pre-morbid conditions, and with increased blood pressure variability. Enhanced casual standard deviations of diastolic blood pressure [1.19 (1.02 to 1.39)] and mean arterial pressure [1.20 (1.00 to 1.43)] predicted dependency at 1-month. Predictors of 12-month dependency included: enhanced casual standard deviation of mean arterial pressure [1.21 (1.0-1.46)]; 24-hour ambulatory monitor standard deviations of diastolic blood pressure [2.30 (1.08-4.90)] and mean arterial pressure [1.72 (1.09-2.72)], and the coefficient of variation of mean arterial pressure [1.76 (1.05-2.94)]; day-time ambulatory monitor coefficient of variation of systolic blood pressure [1.44 (1.02-2.03)] and mean arterial pressure [1.46 (1.02-2.08)]; and night-time ambulatory standard deviation of diastolic blood pressure [1.65 (1.03 -2.63)], and the coefficient of variation of mean arterial pressure and [1.38 (1.00- 1.90)] and pulse pressure [1.29 (1.00–1.65)]. Conclusion: Increasing blood pressure variability is independently and modestly associated with poor functional outcome at 1- and 12-months following acute stroke

Editorial of the special issue on autonomic nervous system and cerebral blood flow autoregulation

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