Decreased upper MAP bound and a narrower MAP range for maintained CVR were associated with poor outcome and more severe brain injury assessed with NfL. Impaired CVR over 48 h was more common in patients with chronic hypertension and associated with poor outcome. NfL concentrations were higher in patients with impaired CVR compared to those with intact CVR (43 IQR vs 20 IQR pg/ml, p = 0.042). The MAP range of maintained CVR was narrower in all time intervals and intervention groups ( p < 0.05). Patients with poor outcomes had a decreased upper MAP bound of CVR over time ( p = 0.001), including the high-normal oxygen ( p = 0.002), carbon dioxide ( p = 0.012) and MAP ( p = 0.001) groups. Integrated TO x for 0–48 h was higher in patients with poor outcome than in patients with good outcome (0.89 95% CI vs. In 108 patients with sufficient data to calculate TO x, 76 patients (70%) had impaired CVR and among these, chronic hypertension was more common (58% vs.

Secondary outcomes included associations with MAP bounds for CVR and biomarkers of brain injury. The primary outcome was the association between TO x and six-month functional outcome dichotomised by the cerebral performance category (CPC1-2 good vs. TO x was analysed in the 0–12, 12–24, 24–48 h time-periods and integrated over 0–48 h.

The tissue oximetry index (TO x) generated by the moving correlation coefficient between cerebral tissue oxygenation measured by NIRS and MAP was used as a dynamic index of CVR with TO x > 0 indicating impaired reactivity and TO x > 0.3 used to delineate the lower and upper MAP bounds for disrupted CVR. MethodsĪ post-hoc analysis of 120 comatose OHCA patients continuously monitored with NIRS and randomised to low- or high-normal oxygen, carbon dioxide and mean arterial blood pressure (MAP) targets for 48 h. We studied the incidence and features of CVR by near infrared spectroscopy (NIRS) and associations with outcome and biomarkers of brain injury. Although the study group is small, there seems to be considerable potential for guiding preoperative decisions and monitoring efficacy of surgical revascularization.Impaired cerebrovascular reactivity (CVR) is one feature of post cardiac arrest encephalopathy. Magnetic imaging-based CVR mapping during rapid manipulation of end-tidal PCO 2 is an exciting new method for determining the location and extent of abnormal vascular reactivity secondary to proximal large-vessel stenoses in moyamoya disease. Postsurgical reactivity maps demonstrated improvement in the two patients with positive clinical outcome and no change in the patient in whom a failed superficial temporal artery-middle cerebral artery bypass was performed.Ĭonclusions. Presurgical CVR maps showed distinct regions of positive and negative reactivity that correlated precisely with the vascular territories supplied by severely narrowed vessels. The CVR maps were then calculated by comparing the percentage of changes in MR signal with changes in end-tidal PCO 2. Measurements of CVR were obtained by rapidly manipulating end-tidal PCO 2 between hypercapnic and hypocapnic states during MR imaging. Three patients with angiographically confirmed moyamoya disease were evaluated before and after surgical revascularization. Preoperative and postoperative results are reported in three cases to demonstrate the efficacy of this technique in assessing vascular reserve at the microvascular level. This paper introduces a new noninvasive magnetic resonance (MR) imaging-based method to map CVR. The ability to map cerebrovascular reactivity (CVR) at the tissue level in patients with moyamoya disease could have considerable impact on patient management, especially in guiding surgical intervention and assessing the effectiveness of surgical revascularization.

Cerebrovascular reactivity definition