Chest patch for continuous vital-sign monitoring: A clinical validation study during movement and controlled hypoxia. (Preprint)
Morgado Areia C., Santos M., Vollam S., Pimentel M., Young L., Roman C., Ede J., Jones P., King E., Gustafson O., Harford M., Shah A., Tarassenko L., Watkinson P.
BACKGROUND Early warning scores in general wards are commonly limited by intermittent manual measurements; these are recognised as being time consuming and for impacting monitoring frequency. Wearable devices may support healthcare staff, improve patient safety and promote early deterioration detection. However available ambulatory monitoring devices need to be tested and validated before clinical implementation. OBJECTIVE The objective of this study is to determine the agreement between a chest-worn patch (VitalPatch®) and gold standard reference device for heart rate (HR) and respiratory rate (RR) measurements during movement and during gradual de-saturation in a controlled environment. METHODS After both VitalPatch and gold standard device (Philips MX450) were placed, participants performed 7 different movements: At rest, Sit-to-Stand, Tapping, Rubbing, Drinking, Turning Pages, and Using a Tablet. In a controlled environment. Participants were then made hypoxic gradually down to 80% peripheral oxygen saturations. The primary outcome measures were the accuracy, defined as the mean absolute error (MAE) of the VitalPatch estimates when compared with their gold-standards. We defined these to be clinical acceptable if within 5 beats per minute (bpm) for HR and 3 respirations per minute (rpm) for RR. RESULTS We acquired complete datasets of 29 participants. In the movement phase, HR estimates were within the pre-specified limits for all movements. For RR, estimates were also inside the acceptable range, with the exception of the Sit-to-Stand and Turning Pages movements, showing a MAE (95% CI) of 3.05 (2.48, 3.58) rpm and 3.45 (2.71, 4.11) rpm, respectively. For the hypoxia phase, these were always within the limits with an overall MAE for HR and RR of 0.72 (0.66, 0.78) bpm and 1.89 (1.75, 2.03) rpm, respectively. There were no significant differences in the VitalPatch performance across a range of oxygen desaturations. CONCLUSIONS The VitalPatch was highly accurate throughout movement tests except for its RR estimation during two movements. This device was reliable throughout the hypoxia stages, with no significant accuracy differences in normoxia (≥ 90%), mild (89.9 - 85%) and severe hypoxia (< 85%). CLINICALTRIAL ISRCTN61535692