We investigated the association of increased cerebral blood flow velocity with specific language abilities in children with sickle cell disease (SCD). Thirty-nine children ages 5 to 8 years old with high-risk genotypes of SCD underwent cognitive testing, which included tests of language skills, visual motor skills, and attention/working memory as part of a routine hematology health-maintenance visit. Transcranial Doppler (TCD) velocities were obtained from review of medical records, with the velocities that were in closest temporal proximity to the cognitive assessment used in the analysis. TCD velocities predicted scores on tests of syntactical skills, even when controlling for anemia severity. Semantic and phonological ability and other cognitive skills were not strongly related to TCD velocities. Elevated blood flow velocities in children with high-risk SCD may contribute to a specific language impairment or to a broader dysfunction of short-term and/or working memory. This study underscores the need for clinicians to monitor language skills of children with SCD who have elevated TCD velocities, as these cognitive abilities might be particularly sensitive to cerebrovascular disruption related to their disease. (JINS, 2010, 16, 326–334.)

Background and objective: Assessment of the effects of normovolaemic haemodilution on middle cerebral artery blood flow velocity with transcranial Doppler ultrasonography, intracranial pressure, cerebral perfusion pressure, arterial oxygen content and cerebral oxygen delivery.

Methods: Normovolaemic haemodilution was induced in rabbits under general anaesthesia, and the haematocrit was allowed to decrease to 30% in Group 1 (n = 6) and to 20% in Group 2 (n = 6). Peak systolic and diastolic velocities, mean blood flow velocity, and pulsatility and resistance indices of the middle cerebral artery were measured by transcranial Doppler ultrasonography. Changes in intracranial pressure, cerebral perfusion pressure, arterial oxygen content and cerebral oxygen delivery were also assessed.

Results: In Group 2, middle cerebral artery blood flow velocity increased from 0.4 ± 0.01 to 0.51 ± 0.02 m s−1 after the induction of normovolaemic haemodilution (P = 0.04), while arterial oxygen content decreased from 16.2 ± 0.1 to 8.5 ± 0.1 mL dL−1 (P = 0.002). The decrease in cerebral oxygen delivery from 6.5 ± 0.2 to 4.3 ± 0.2 was also significant (P = 0.02). However, no associated changes in intracranial pressure and cerebral perfusion pressure could be demonstrated.

Conclusions: Normovolaemic haemodilution resulted in an increase in the mean blood flow velocity of the middle cerebral artery. However, this increase did not compensate for the consequences of the altered oxygen delivery to the brain when the haematocrit was reduced to 20%

Background and objective The recently developed transcerebral double-indicator dilution technique has proven to be a feasible monitoring alternative to measure global cerebral blood flow at the bedside. However, the short-term repeatability of transcerebral double-indicator dilution measurements has not yet been investigated. The present study was designed to investigate the accuracy in terms of reliability for repeated transcerebral double-indicator dilution measurements to assess global cerebral blood flow during a definite carbon dioxide challenge in a clinical trial.

Methods The investigation was performed in 10 patients scheduled for elective coronary artery bypass grafting. After induction of anaesthesia, repeated cerebral blood flow measurements using transcerebral double-indicator dilution were performed during target normocapnia, hypocapnia and hypercapnia. For transcerebral double-indicator dilution measurements, a bolus injection of ice-cold indocyanine green was administered into a central vein. The resulting thermal dye dilution curves were recorded simultaneously in the aorta and the jugular bulb using combined fibreoptic thermistor catheters. Cerebral blood flow was calculated from the mean transit times of the indicators through the brain. Additionally, transcranial Doppler sonography was simultaneously performed to measure transient changes in the cerebral blood flow velocity.

Results Transcerebral double-indicator dilution measurements revealed a reasonable coefficient of repeatability with 9.1, 9.7 and 20.2 mL min−1100 g−1 during normo-, hypo- and hypercapnic conditions, respectively. However, a total of 20% of the administered measurements had to be rejected for methodological reasons.

Conclusions Repeated measurements with the transcerebral double-indicator dilution method show a reasonable repeatability. With consideration to the limitations of the transcerebral double-indicator dilution technique, this new method proves to be a reliable monitoring tool to measure global cerebral blood flow at the bedside.

Background and objective We studied the influence of systemic (aortic) blood flow velocity on changes of cerebral blood flow velocity under isoflurane or sevoflurane anaesthesia.

Methods Forty patients (age: isoflurane 24–62 years; sevoflurane 24–61 years; ASA l–lll) requiring general anaesthesia undergoing routine spinal surgery were randomly assigned to either group. Cerebral blood flow velocity was measured in the middle cerebral artery by transcranial Doppler sonography (depth: 50–60 mm). Systemic blood flow velocity was determined by transthoracic Doppler sonography at the aortic valve. Heart rate, arterial pressure, arterial oxygen saturation and body temperature were monitored. After standardized anaesthesia induction (propofol, remifentanil, vecuronium) sevoflurane or isoflurane were used as single agent anaesthetics. Cerebral blood flow velocity and systemic blood flow velocity were measured in the awake patient (baseline) and repeated 5 min after reaching a steady state of inspira-tory and end-expiratory concentrations of 0.75, 1.00, nd 1.25 mean alveolar concentrations of either anaesthetic. To calculate the influence of systemic blood flow velocity on cerebral blood flow velocity, we defined the cerebral-systemic blood flow velocity index (CSvl). CSvl of 100% indicates a 1:1 relationship of changes of cerebral blood flow velocity and systemic blood flow velocity.

Results Isoflurane and sevoflurane reduced both cerebral blood flow velocity and systemic blood flow velocity. The CSvl decreased significantly at all three concentrations vs. 100% (isoflurane/sevoflurane: 0.75 MAC: 85 ± 25%/81 ± 23%, 1.0 MAC: 79 ± 19%/74 ± 16%, 1.25 MAC: 71 ± 16%/79 ± 21%; [mean ±SD] P% 0.0001). Conclusions The reduction of the CSvl vs. 100% indicates a direct reduction of cerebral blood flow velocity caused by isoflurane/sevoflurane, independently of systemic blood flow velocity.