Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Near infrared laser device can measure brain oxygen levels

24.10.2005


A new device that uses near-infrared light to non-invasively monitor the oxygenation of the brain during surgery appears to be a promising alternative to the more invasive techniques currently in use, according to a new study by Duke University Medical Center anesthesiologists.



The researchers said their findings offer the potential for accurate and reliable monitoring of brain oxygenation during cardiac surgeries, to more effectively protect the brain against reduced oxygen levels, or anoxia, which is known to cause cognitive impairment in some surgical patients.

During some surgeries anesthesiologists measure venous oxygenation by periodically removing blood samples from catheters inserted in major blood vessels in the neck and then analyze the samples by co-oximetry. Also, anesthesiologists frequently use a pulse oximeter, attached to the patient’s finger, to measure arterial blood oxygenation. However, since these measurements are taken on blood outside the brain, physicians can only estimate the level of cerebral oxygenation.


Designed by CAS Medical Systems, Inc., the monitor, called a cerebral oximeter, uses one or more sensors attached to the forehead that emit non-harmful, low-level laser light through the skin and skull into the brain. Since the near-infrared light absorption characteristics of the hemoglobin in red blood cells are known, the system can calculate the brain tissue oxygen saturation by measuring the differences in intensity of light as it passes through the brain. When combined with pulse oximetry, the cerebral oximeter may be used to estimate the cerebral venous oxygen saturation.

The basic principle of cerebral oximetry is based on optical spectroscopy techniques. The discovery that near-infrared light can pass through the scalp and skull to examine levels of hemoglobin and other light absorbing compounds of the brain was made at Duke by Frans Jobsis, Ph.D., in 1977.

"It has always been a challenge to directly measure the oxygen levels in the brain," said Duke anesthesiologist David MacLeod, M.D., who presented the results of the Duke study Oct. 22, 2005, at the annual scientific sessions of the American Society of Anesthesiologists in Atlanta. "The main issues with the invasive approach are that it does not provide specific information in real time, and it is of course invasive, which can carry some risk to the patient.

"This new technology, which is non-invasive and provides real-time information, appears to be an accurate means for measuring cerebral oxygenation and indirectly cerebral perfusion," MacLeod said. "As anesthesiologists, protecting the brain from potential harm is one of the main functions we perform during a surgical procedure."

For their study, the researchers enrolled 12 healthy volunteers. The volunteers were monitored using the different blood oxygenation measurement systems – pulse oximetry, jugular and radial arterial co-oximetry, and the prototype cerebral oximeter. In a stepwise fashion, the researchers decreased and then increased the concentration of inhaled oxygen through a range of 70 to 100 percent arterial blood oxygen saturation. Frequent, concurrent measurements were made on all three systems throughout the process.

"We made a total of 171 readings and found a strong correlation between the reference co-oximetry measurements by the invasive methods to the non-invasive approaches," MacLeod said. "So it appears that we can use non-invasive approaches to estimate something we could in the past only measure with invasive sampling."

While pulse oximetry is used universally to measure arterial oxygen saturation for all patients undergoing surgery, interest in cerebral oxygenation levels have mainly been the domain of cardiac surgeons and anesthesiologists, according to MacLeod, given the rising concerns about potential cognitive impairments suffered by some patients undergoing open heart surgery.

Following this successful validation of the CAS cerebral oximeter, the Duke team is conducting a clinical trial to refine the optimal range of cerebral oxygenation in patients undergoing heart surgery. After surgery these patients will be periodically assessed to detect any correlation between cerebral oxygen levels during surgery and post-op changes in cognition.

Richard Merritt | EurekAlert!
Further information:
http://www.mc.duke.edu

More articles from Health and Medicine:

nachricht Penn studies find promise for innovations in liquid biopsies
30.03.2017 | University of Pennsylvania School of Medicine

nachricht 'On-off switch' brings researchers a step closer to potential HIV vaccine
30.03.2017 | University of Nebraska-Lincoln

All articles from Health and Medicine >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: A Challenging European Research Project to Develop New Tiny Microscopes

The Institute of Semiconductor Technology and the Institute of Physical and Theoretical Chemistry, both members of the Laboratory for Emerging Nanometrology (LENA), at Technische Universität Braunschweig are partners in a new European research project entitled ChipScope, which aims to develop a completely new and extremely small optical microscope capable of observing the interior of living cells in real time. A consortium of 7 partners from 5 countries will tackle this issue with very ambitious objectives during a four-year research program.

To demonstrate the usefulness of this new scientific tool, at the end of the project the developed chip-sized microscope will be used to observe in real-time...

Im Focus: Giant Magnetic Fields in the Universe

Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.

The results will be published on March 22 in the journal „Astronomy & Astrophysics“.

Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...

Im Focus: Tracing down linear ubiquitination

Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.

Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...

Im Focus: Perovskite edges can be tuned for optoelectronic performance

Layered 2D material improves efficiency for solar cells and LEDs

In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...

Im Focus: Polymer-coated silicon nanosheets as alternative to graphene: A perfect team for nanoelectronics

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

International Land Use Symposium ILUS 2017: Call for Abstracts and Registration open

20.03.2017 | Event News

CONNECT 2017: International congress on connective tissue

14.03.2017 | Event News

ICTM Conference: Turbine Construction between Big Data and Additive Manufacturing

07.03.2017 | Event News

 
Latest News

'On-off switch' brings researchers a step closer to potential HIV vaccine

30.03.2017 | Health and Medicine

Penn studies find promise for innovations in liquid biopsies

30.03.2017 | Health and Medicine

An LED-based device for imaging radiation induced skin damage

30.03.2017 | Medical Engineering

VideoLinks
B2B-VideoLinks
More VideoLinks >>>