The device could also be used to monitor patients who survive aneurysm ruptures, a high proportion of whom develop vasospasm. For such patients, a technician would typically measure blood flow with an ultrasound once or twice a day during a hospital stay of several days. Kliot says the new device makes it possible to continuously monitor patients at high risk, and for longer periods of time. “We see putting it on the head and measuring constantly or frequently over two weeks,” says Kliot.
Nerissa Ko, a neurologist in the intensive care unit at University of California San Francisco Medical Center, says the device is building on a well-accepted diagnostic technology, with the added innovation of automation. If it proves effective, she says, the device could make it easier to track blood flow over time, which she says is the best way to detect vasospasm.
Brad Harlow, president and CEO of PhysioSonics, says the company has conducted a study comparing the algorithm’s accuracy to a technician’s and is filing for approval from the U.S. Food and Drug Administration within the month.
The company has also been developing an algorithm that would use the same technology to monitor pressure inside the head. Such monitoring currently requires doctors to drill a hole in the skull. Ko cautions, however, that while the blood-flow changes detected by ultrasound could serve as a surrogate for direct pressure measurements, it’s still not clear if the device is sensitive enough to monitor the subtle changes that can signal danger.