Select your localized edition:

Close ×

More Ways to Connect

Discover one of our 28 local entrepreneurial communities »

Be the first to know as we launch in new countries and markets around the globe.

Interested in bringing MIT Technology Review to your local market?

MIT Technology ReviewMIT Technology Review - logo


Unsupported browser: Your browser does not meet modern web standards. See how it scores »

{ action.text }

Patients with severe injuries or serious infections run the risk of circulatory shock–a life-threatening condition in which the blood can’t supply tissues with enough oxygen and nutrients. If shock is recognized in time, the patient can be resuscitated with oxygen, intravenous fluids, and medications. But catching shock early is no simple matter. A small infrared sensor currently under development at the University of Massachusetts Medical School promises to detect impending shock earlier than any other noninvasive test.

Traditionally, patients in critical condition are continuously monitored for changes in blood pressure, heart rate, and pulse oxygen saturation. But the body has mechanisms to compensate for massive blood loss and systemic infection, keeping those parameters steady even while the patient’s status deteriorates. “When the blood pressure starts to drop, it’s too late,” says spectroscopist Babs Soller, who developed the new device along with colleagues at the UMass Medical School. “The patient is already going into shock.” The new device instead measures the levels of oxygen, pH, and hematocrit–the proportion of red blood cells in the blood–in a patient’s muscle tissue.

“Until now, we’ve either had noninvasive methods which are very insensitive, like blood pressure, or we’ve had sensitive methods that are invasive and cumbersome,” says George Velmahos, chief of trauma, emergency surgery, and surgical critical care at Massachusetts General Hospital, who was not involved in developing the device. “So the noninvasive and continuous nature of this method is key.”

Soller’s device beams near-infrared light through the skin over an arm or leg muscle, where it travels through fat and reflects off muscle tissue and back to the monitor. Based on the spectrum of the reflected light, computer algorithms determine the oxygen, pH, and hematocrit levels. Unlike similar infrared biomeasurement devices, the new monitor automatically compensates for differences in skin color and fat thickness between patients to optimize the results.

One of the ways that the body compensates for blood loss or impaired circulation is by prioritizing which tissues most need oxygen. Blood is shunted away from skeletal muscles and internal organs and delivered instead to the heart and brain. A pulse oximeter, which analyzes the blood before it has delivered oxygen to tissues, can’t tell whether this kind of compensation is occurring. Because the new device measures oxygen within the muscle, it can give a more complete picture of how well the blood is feeding peripheral tissues. A substantial drop in muscle oxygen while pulse oxygen saturation remains steady could indicate that the patient is compensating for internal bleeding and will soon “crash.”

0 comments about this story. Start the discussion »

Credit: Gwenn Ellerby, University of Massachusetts Medical School

Tagged: Computing, Biomedicine, health, devices, health IT, medical diagnostics, blood pressure

Reprints and Permissions | Send feedback to the editor

From the Archives


Introducing MIT Technology Review Insider.

Already a Magazine subscriber?

You're automatically an Insider. It's easy to activate or upgrade your account.

Activate Your Account

Become an Insider

It's the new way to subscribe. Get even more of the tech news, research, and discoveries you crave.

Sign Up

Learn More

Find out why MIT Technology Review Insider is for you and explore your options.

Show Me