Abstract Details

Title Changes in Head Pulse and Cranial Accelerometry Signals in Patients Undergoing Systemic Fluid Shifts

Topic Neuro Trauma and Critical Care

Presentation(s) P9 - Poster Session 9 (11:45 AM-12:45 PM)

Poster/Presentation
Number 7-003

Objective

In this observational cohort study, we hypothesize that patients undergoing routine fluid shifts exhibit characteristic cranial accelerometry signatures at different fluid balances.

Background In patients with critical neurologic illness, close monitoring of fluid status is needed to identify patients at risk for secondary neurologic injury – especially during routine large-volume fluid shifts seen during diuresis and hemodialysis or in neurologic alterations of fluid homeostasis such as cerebral salt wasting. Recent studies have suggested that skull motion produced by pulsatile cerebral blood flow may a useful tool in vasospasm and cerebral edema; therefore, identification of a unique cranial accelerometry signal seen in systemic fluid shifts may be a valuable adjunct neuromonitoring tool.

Design/Methods

Head pulse recordings were obtained prior to, during, and after hemodialysis using a device consisting of a headband-mounted triaxial accelerometer, circuit board, and electrocardiogram. This data was analyzed using MATLAB2022a, summed to generate a time-domain force signal, converted to the frequency domain using a Discrete Fourier Transform, normalized to the amplitude of the most prominent frequency band (5Hz), and weighted/averaged by volume removal.

Results

Recordings were obtained in 14 subjects (9 inpatient, 5 outpatient). Average recording duration was 182min (+/-8.0min), average weight change was 2.2kg (+/-0.87kg), and average volume removed was 2172mL (+/-859.2mL). There was a significant 29% reduction in the 6Hz frequency band in pre-dialysis recordings compared to a 43% increase in dialysis recordings and a shift towards higher frequencies in all bands during dialysis. There were no observable changes in frequency throughout individual hemodialysis sessions.

Conclusions

There was a significant increase in volume-corrected head pulse frequencies in dialysis recordings compared to pre-dialysis recordings. These unique cranial accelerometry signatures may be reflective of mildly increased brain volume or resistance. Further studies are needed to clarify this relationship and to evaluate the role of cranial accelerometry in patients with abnormal neurologic presentations.

Authors/Disclosures
Derrick Cheng, MD (UCSF Medical Center) PRESENTER	Dr. Cheng has nothing to disclose.
Eliot Lee, Clinical Research Coordinator	Mr. Lee has nothing to disclose.
Wade S. Smith, MD, PhD (University of California, San Francisco)	Dr. Smith has stock in MindRhythm, Inc. The institution of Dr. Smith has received research support from NIH. Dr. Smith has received intellectual property interests from a discovery or technology relating to health care. Dr. Smith has received publishing royalties from a publication relating to health care.

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