Utility of a Novel Watch-based Pulse Detection System to Detect Pulselessness in Human Subjects

Background: The Wriskwatch is a novel, watch-based pulse detection device that detects the loss of a radial pulse via advanced pulse detection technology and immediately contacts emergency medical systems.

Objective: The purpose of this first-in-man, prospective, single-blinded, phase 1 study was to evaluate the ability of this device to detect motionlessness and pulselessness in human subjects as a simulation of sudden cardiac death.

Methods: The study cohort consisted of 34 patients: 24 hospitalized patients and 10 presenting for implantable cardioverter-defibrillator (ICD) testing. We simulated loss of pulse in our hospitalized patients via blood pressure cuff inflation to occlude the brachial arterial pulse at random times in 20 subjects with no inflations in 4 while the patients were instructed to keep perfectly still. Of the 10 patients undergoing ventricular fibrillation (VF) induction during ICD testing, the exact times of VF induction were recorded. A blinded reviewer determined if and when motion and pulse were lost in all patients using only data from the device.

Results: Of the 34 patients, 2 had an unusable signal, 1 had device ejection during ICD testing, and 2 had too much motion artifact and were excluded (5/34 patients, or 14.7% of the total cohort). Of the 29 remaining subjects, 4 had no loss of pulse of which the device correctly identified 3. In the remaining 25 patients, the device correctly identified the time of pulselessness in 23 of 25 (16/17 hospitalized patients and 7/8 ICD patients). Overall, the Wriskwatch was worn for a total of 561.2 minutes. Pulselessness was present for 5.8 minutes. The sensitivity of the watch to detect pulse status (based on 15-second intervals) was 99.9%, and the specificity was 90.3%.

Conclusion: The Wriskwatch is a novel device that shows promise as a tool to hasten activation of emergency medical systems and facilitate early defibrillation in patients with cardiac arrest.