‘No Touch’ Vitals: A Pilot Study of Non-contact Vital Signs Acquisition in Exercising Volunteers

Accurate non-contact acquisition of patient vital signs will advance emergency care. In order to assess promising candidate technologies., an observational study was conducted with healthy volunteers to test two hypotheses: 1. Video photoplethysmography and motion analysis (vPPG-MA) and infrared thermography (IR) will accurately and concurrently measure heart rate (HR) and respiratory rate (RR), and body temperature, respectively. 2. Non-contact approaches will exhibit comparable and reliable performance against standard contact cardiorespiratory monitors (CM). HR and RR were measured with CM and vPPG-MA; core and surface temperatures were obtained using oral thermometry and two IR cameras, respectively. Subjects were videorecorded at rest; during sustained exercise at 50%, 60%, and 70% of age-predicted maximum HR; and 1, 3, and 5 min post-exertion. vPPG-MA HR and RR measurements were calculated for video segments corresponding to ED use-cases: Triage (unprimed) 30s check, Routine 30s check, Abbreviated “Spot” 10s check, and Full 60s check. Descriptive statistics and Bland-Altman analyses were performed on vPPG-MA and IR measurements against synchronous CM measurements. Thirty volunteers exhibited a HR range of 43-146bpm, a RR range of 8-29bpm, and an oral temperature range of 96.2-99.5°F on CM. vPPG-MA obtained 972 (98.2% of scheduled) HR and 591 (98.5%) RR measurements; mean differences between Full 60s vPPG-MA and CM were -0.9±5.5bpm (-0.9±5.3%; 95% CI: -11.6-9.8bpm) for HR, and 0.9±3.1bpm (4.8±17.6%; -5.1-6.9bpm) for RR; other video segments performed similarly. IR acquired temperatures ~4°F lower than oral thermometers. vPPG-MA and IR thermography successfully measured select vital signs concurrently. vPPG-MA`s observed level of agreement with CM, along with temperature offsets identified for IR-based thermometry, have set the foundation for live ED clinical studies.