Modulation of the carotid baroreflex using a novel, low-cost, low-noise, MRI-safe variable-pressure neck chamber system

Modulation of the carotid baroreflex can be performed in research, teaching, and clinical settings using variable-pressure neck chambers. However, there are only a small number of commercially available systems, which are expensive. Furthermore, most systems are not compatible with magnetic resonance imaging (MRI), as they contain metallic components or are too bulky to fit within the MRI bore. Therefore, the purpose of the present project was to develop a variable-pressure neck chamber system for less than $1500 USD using commonly sourced parts that are MRI-compatible. The components of our variable-pressure neck chamber system consisted of an AC/DC converter, diaphragm pump, timer, solenoid valves (S/V), acrylonitrile butadiene styrene (ABS) pipe, swimming goggles, pneumatic kill switch, and voltage regulator, all sourced from common hardware suppliers or Amazon.ca. The assembled system fits on a 51 x 71 cm (20 x 28 in) table surface and weighs ~8 kg (~18 lb.). The sourced goggles (neck chambers) and pneumatic kill switch were made from plastic compounds, permitting safe use within an MRI. All supplies purchased to construct this system totaled <$1,200 USD. Solenoid valve position duration and cycle count (open-closed = one cycle) were programmed independently through the timer and wired to a trigger switch to enable users to easily adjust stimulus duration and frequency and activate the system with a single button press. Performance tests consisted of applying localized positive and negative pneumatic pressures (20 s stimulus duration) to the carotid sinuses through a range from +60 to -60 mmHg in steps of 20 mmHg. The data indicate our variable-pressure neck chamber system is capable of delineating a stimulus-response relationship for both the blood pressure (decrease: -6±1 mmHg, increase: 9±3 mmHg, range: -7 to 13 mmHg) and the heart rate (decrease: -9±2 bpm, increase: 12±3 bpm, range: -10 to 15 bpm) components of the baroreflex. Technical data reveal the system operates quietly (34.0±1.50 dB) and fast with an evacuation rate of 385±35 mmHg/s during suction application and 371±175 mmHg/s during pressure application. The present study demonstrates the successful development of a low-cost, low-noise, MRI-safe variable-pressure neck chamber system built with easily sourced parts. Future design iterations will achieve higher evacuation rates, greater portability, and integrate automated R-wave gated stimulus application. Funding: NSERC Discovery Grant (#05323) This abstract was presented at the American Physiology Summit 2025 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.