Ultrasound detection of abnormal cerebrovascular morphology in a mouse model of sickle cell disease based on wave reflection

Sickle cell disease (SCD) is associated with a high risk of stroke, and affected individuals often have focal brain lesions termed silent cerebral infarcts. The mechanisms leading to these types of injuries are at present poorly understood. Our group has recently demonstrated a non-invasive measurement of cerebrovascular impedance and wave reflection in mice using high-frequency ultrasound in the common carotid artery. To better understand the pathophysiology in SCD, we used this approach in combination with micro-computed tomography to investigate changes in cerebrovascular morphology in the Townes mouse model of SCD. Relative to controls, the SCD mice demonstrated the following: (i) increased carotid artery diameter, blood flow and vessel wall thickness; (ii) elevated pulse wave velocity; (iii) increased reflection coefficient; and (iv) an increase in the total number of vessel segments in the brain. This study highlights the potential for wave reflection to aid the non-invasive clinical assessment of vascular pathology in SCD

Hemoglobin Area and Time Index Above 90\ua0g/L are Associated with Improved 6-Month Functional Outcomes in Patients with Severe Traumatic Brain Injury

Purpose: There is conflicting data on the relationship between anemia and outcomes in patients with traumatic brain injuries (TBI). The objective of this study was to determine if the proportion of time and area under the hemoglobin-time curve of\ua0 6590\ua0g/L are independently associated with 6-month functional outcomes. Methods: Retrospective cohort study of 116 patients with a severe TBI who underwent invasive neuromonitoring between June 2006 and December 2013. Hemoglobin area (HAI) and time (HTI) indices were calculated by dividing the total area, or time, under the hemoglobin-time curve at 90\ua0g/L or above by the total duration of monitoring. Multivariable log-binomial regression was used to model the association between HAI or HTI and 6\ua0month favorable neurologic outcome (Glasgow Outcome Score 4 or 5). Results: Patients had a mean age of 38\ua0years (SD 16) with a median admission Glasgow Coma Scale of 6 (IQR 4\u20137). There were 1523 hemoglobin measurements and 523 monitoring days. Patients had a hemoglobin\ua0 6590\ua0g/L for a median of 70\ua0% (IQR 37\u2013100) of the time. Each 10\ua0g/L increase in HAI (RR 1.23, 95\ua0%CI 1.04\u20131.44, P\ua0=\ua00.011), and 10\ua0% increase in HTI (1.10, 95\ua0%CI 1.04\u20131.16, P\ua0<\ua00.001) were associated with improved neurologic outcome. Thirty-one patients (27\ua0%) received a transfusion with the median pre-transfusion hemoglobin being 81\ua0g/L (IQR 76\u201387). Conclusions: In patients with severe TBI, increased area under the curve and percentage of time that the hemoglobin concentration was\ua0 6590\ua0g/L, were associated with improved neurologic outcomes