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This near-infrared spectroscopy device, which emits near-infrared light that penetrates the scalp
and underlying brain tissue, has been used in animals to study brain
blood, so the Mayo Clinic team thought that measuring the same
parameters in stroke patients might be useful.
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A
research team led by investigators at Mayo Clinic in Florida has found
that a small device worn on a patient's brow can be useful in monitoring
stroke patients in the hospital. The device measures blood oxygen,
similar to a pulse oximeter, which is clipped onto a finger.
Their
study, published in the Feb. 1 issue of Neurosurgical Focus, suggests
this tool, known as frontal near-infrared spectroscopy (NIRS), could
offer hospital physicians a safe and cost-effective way to monitor
patients who are being treated for a stroke, in real time.
"About
one-third of stroke patients in the hospital suffer another stroke, and
we have few options for constantly monitoring patients for such
recurrences," says the study's senior investigator, neurocritical care
specialist William Freeman, M.D., an associate professor of neurology at
Mayo Clinic.
"This
was a small pilot study initiated at Mayo Clinic's campus in Florida,
but we plan to study this device more extensively and hope that this
bedside tool offers significant benefit to patients by helping
physicians detect strokes earlier and manage recovery better," he says.
Currently,
at most hospitals nurses monitor patients for new strokes and, if one
is suspected, patients must be moved to a hospital's radiology unit for a
test known as a CT perfusion scan, which is the standard way to measure
blood flow and oxygenation. This scan requires that a contrast medium
be used, and the entire procedure can sometimes cause side effects such
as excess radiation exposure if repeated scans are required. Also,
potential kidney and airway damage can result from the contrast medium.
Alternately,
for the sickest patients, physicians can insert an oxygen probe inside
the brain to measure blood and oxygen flow, but this procedure is
invasive and measures only a limited brain region, Freeman says.
This
NIRS device, which emits near-infrared light that penetrates the scalp
and underlying brain tissue, has been used in animals to study brain
blood, so the Mayo Clinic team thought that measuring the same
parameters in stroke patients might be useful. They set up a study to
compare measurements from NIRS with CT perfusion scanning in eight
stroke patients.
The
results show that both tests offer statistically similar results,
although NIRS has a more limited field for measuring blood oxygen and
flow. "That suggests that perhaps not all patients would benefit from
this kind of monitoring," he says.
The
device sticks like an adhesive bandage onto each of the patient's
eyebrows and works like the pulse oximeter that is usually used on a
patient's finger to monitor health or brain perfusion during surgery.
If
the device is successfully tested in upcoming studies and miniaturized,
the NIRS might also be useful in military settings to assess and
monitor blood functioning due to brain injuries, Freeman says.
Researchers
from the University of South Florida College of Medicine and the
University of North Florida College of Medicine participated in the
study, along with several college students who were participating in
Mayo Clinic's Clinical Research Scholar Program (CRISP).
"This
research could not have been accomplished without the dedication and
assistance from our CRISP premedical student Brandon O'Neal, and
vascular neurosurgery fellow Philipp Taussky, M.D.," notes Freeman. "We
are excited about the future possibilities in which this tool would be
very useful."
The
study was approved by the Mayo Clinic IRB and not sponsored or funded
by any company. The authors declare no conflicts of interest.
Validation of frontal near-infrared spectroscopy as noninvasive bedside monitoring for regional cerebral blood flow in brain-injured patients
SOURCE
