Image: A new study describes how acoustic signals can be used to monitor intracranial pressure (Photo courtesy of HeadSense Medical).
A new study describes how advanced acoustic signal analysis algorithms can be used to noninvasively evaluate intracranial pressure (ICP).
Researcher at Klinikum Stuttgart (Germany) and the University of Erlangen (Germany) used the HeadSense Medical (Netanya, Israel) HS-1000 device to generate and measure acoustic signals passing throughout the cranium. The six-second, 66 dB bursts of sound are emitted in one ear and received by sensors located in the opposite ear. Advanced signal analysis algorithms are used to evaluate properties of the acoustic signals for constant evaluation of ICP. Data corresponding to the 6-second epoch are recorded and displayed on the device monitor.
In a study of the new device, the researchers tested noninvasive ICP monitoring in 14 patients who were already receiving treatment for traumatic brain injury and/or subarachnoid hemorrhage in an intensive care unit (ICU), with invasive intraventricular or intraparenchymal monitoring catheters already in place. The researchers then compared ICP values obtained from a total of 2,543 data points of continuous ICP monitoring using the noninvasive HS-1000 device with concurrent ICP values obtained using invasive monitoring.
The results showed a strong association between ICP values obtained using both the noninvasive and invasive methods. Differences in mean ICP values were +/- 3 mm Hg in 63% of data-paired readings, and +/- 5 mm Hg in 85% of data-paired readings, similar to the differences found in studies that compared invasive intraventricular to intraparenchymal monitoring. The resulting sensitivity and specificity of the noninvasive ICP monitoring were determined to be 0.7541 and 0.8887, respectively. The study was published on August 8, 2017, in the Journal of Neurosurgery.
“Overall, the findings show a good correlation between ICP values obtained using noninvasive and invasive methods of monitoring,” concluded lead author Oliver Ganslandt, MD, of Klinikum Stuttgart, and colleagues. “Use of the device could protect patients from infection and hemorrhage, potential risks of invasive ICP monitoring, and also could aid clinicians in deciding when invasive ICP monitoring may be appropriate.”
Normal human ICP is 20 mm Hg or lower, but in the presence of disease or trauma, brain tissues may swell or cerebrospinal fluid (CSF) may increase in volume, causing ICP to increase. ICP monitoring of critical-care patients provides clinicians with the knowledge of whether and when action must be taken to decrease ICP. To perform invasive ICP monitoring, a catheter must be inserted through the patients into brain parenchyma or into a ventricle. An intraventricular catheter can be used both to monitor ICP and to reduce ICP.
University of Erlangen