Trial participants from Queen Mary Hospital and the University of Hong Kong will be
recruited. Potential participants will be contacted and provided with a detailed
explanation of the study, including its purpose, procedures, risks, and benefits. Written
informed consent will be obtained from all participants before enrolment. This process
involves providing individuals with the informed consent document, allowing time for
review and questions, and obtaining their signature if they agree to participate.
Participants will receive a copy of the signed consent form for their records.
At Visit 1, Comprehensive demographic and clinical data will be collected from each
participant, Clinical Management System (CMS), Electronic Patient Record (ePR), and
Clinical Data Analysis and Reporting System (CDARS) of the Hospital Authority in Hong
Kong. This will include age, sex, height, weight, body mass index, and detailed medical
history focusing on cardiovascular conditions. Information about current medications and
smoking status will also be recorded. Additionally, participants will undergo a baseline
clinical examination, including blood pressure measurement, heart rate, and a 12-lead
electrocardiogram.
Participants will undergo a conventional cardiopulmonary exercise test (CPX) to determine
their maximal oxygen uptake (VO2max) at Visit 1. This test will be conducted in a
controlled clinical setting under the supervision of cardiologists. Participants will
exercise on a treadmill while their respiratory gas exchange is measured using a
metabolic cart. The exercise intensity will be gradually increased until the participant
reaches volitional exhaustion or predetermined safety criteria are met. The highest
oxygen uptake value achieved during the test will be recorded as the VO2max. Participant
will concurrently be wearing the investigational smartwatch for pre- and post-SaO2 and
VO2max assessment. This gold-standard measurement will serve as the reference for
validating the smartwatch's continuous VO2max estimation.
The 6-minute walk distance will be assessed in a hospital setting at Visit 2 under the
supervision of a research staff. Participants will be instructed to walk as far as
possible in six minutes along a predetermined course, typically a straight hallway. The
total distance walked will be measured and recorded. During the test, the research nurse
will monitor the participant's heart rate, blood oxygen saturation, and perceived
exertion at regular intervals. Participant will concurrently be wearing the
investigational smartwatch for pre- and post SaO2 and VO2max assessment.
Participants will be provided with a medical-grade pulse oximeter for home use. They will
be instructed to measure their oxygen saturation once daily throughout the one-week study
period. Measurements should be taken at approximately the same time each day, preferably
in the morning after waking and before any strenuous activity. Participants will record
their oxygen saturation readings in a provided log. These daily measurements will serve
as reference points for validating the continuous oxygen saturation data collected by the
smartwatch.