Continuous Regional Cerebral Cortical Blood Flow Monitoring in Head-injured Patients

Abstract

Continuous regional cerebral cortical blood flow (rCoBF) was monitored with thermal diffusion flowmetry in 56 severely head-injured patients. Adequate, reliable data were accumulated from 37 patients (21 acute subdural hematomas, 10 cerebral contusions, 4 epidural hematomas, and 2 intracerebral hematomas). The thermal sensor was placed at the time of either craniotomy or burr hole placement. In 15 patients, monitoring was initiated within 8 hours of injury. One-third of the comatose patients monitored within 8 hours had rCoBF measurements of 18 ml per 100 g per minute or less, consistent with previous reports of significant ischemia in the early postinjury period. Initial rCoBF measurements were similar in the patients with Glasgow Coma Scale scores of 3 to 7 and in those with scores of 8 or greater. In patients with poor outcomes, rCoBF measurements did not change significantly from initial measurements; however, in those patients who had better outcomes, final rCoBF measurements were higher than initial rCoBF measurements. The patients who had better outcomes experienced normalization of rCoBF during the period of monitoring, and patients with poor outcomes had markedly reduced final rCoBF. These changes were statistically significant. When management was based strictly upon the intracranial pressure, examples of inappropriate treatment were found. For example, hyperemia and increased intracranial pressure treated with mannitol caused further rCoBF increase, and elevated intracranial pressure with low cerebral blood flow treated with hyperventilation increased the severity of ischemia. In 3 (5%) of 56 patients, wound infections developed. Continuous rCoBF monitoring in head-injured patients offers new therapeutic and prognostic insights into their management.

Continuous regional cerebral blood flow monitoring in the neurosurgical intensive care unit

“…TDF allows continuous monitoring of CBF in a small area of the brain. 9,[11][12][13][14][15] This may or may not be representative of overall CBF, but the temporal relationships may determine whether treatment is helpful in normalizing CBF, or more importantly, detect early neurological deterioration. As seen in the first group of patients, persistently low rCoBF denotes a poor outcome.…”

“…Head injury may lead to biochemical changes similar to ischemia, and persistent regional ischemia of the brain may lead to permanent secondary brain damage that can predict a poor outcome. [4][5][6][7][8]12,13,16,17 Maintaining adequate cerebral blood flow in severe head injury is thought to be essential for the improvement of outcome. 3 However, a severe head injury may result in patients having either an ischemic or hyperemic brain.…”

“…3 However, a severe head injury may result in patients having either an ischemic or hyperemic brain. 4,6,9,[11][12][13]15 Ischemia may follow a hyperemic episode, as seen in most of the patients in the second group. Treatment should be tailored to each patient depending on whether they have ischemia or hyperemia.…”

“…There has long been a need for a simple way of continuously monitoring CBF reliably. [6][7][8][9][10][11][12][13][14][15] In this clinical study, we present the techniques and results of regional cerebral blood flow (rCoBF) monitoring with thermal diffusion flowmetry (TDF) in our neurointensive care unit. We aimed to examine the correlation between GCS, ICP, rCoBF, and outcome in response to treatment.…”

Towards Non-Invasive Bedside Monitoring of Cerebral Blood Flow and Oxygen Metabolism in Brain-Injured Patients with Near-Infrared Spectroscopy

“…However, the accuracy of TCD is operator dependent due to problems of probe fixation, the TCD signal is not found in 10-30% of patients, and the technique cannot monitor blood flow in the microvasculature, which can be quite different from flow in the major arteries (Wright, 2007). Invasive techniques for monitoring CBF that require inserting probes directly into brain tissue include laser Doppler (LDF) and thermal diffusion flowmetry (TDF) (Bolognese et al, 1993;Sioutos et al, 1995). These techniques have been used to detect ischemia in brain-injured patients and TDF was shown to be more sensitive than TCD to assessing vasospasm, demonstrating the value of assessing CBF directly (Kirkpatrick et al, 1994;Vajkoczy et al, 2001).…”