Validation of Respiratory Rate and Heart Rate Measurements by Capaciflectors Placed in Four Locations on the Chest

RESEARCH QUESTION/AIM(S)

Will a capaciflector measure the respiratory rate as accurately as a pneumotachometer and the heart rate as accurately as an electrocardiogram?

Objectives:

• To test the reliability and accuracy of our capaciflector in measuring respiratory rate and heart rate by comparing it with gold standard readings.
• To assess whether different capaciflector locations around the body are all as accurate as each other.

STUDY DESIGN and METHODS of DATA COLLECTION AND DATA ANALYSIS

Unblinded observational study - for each subject demographic data will be collected: age, gender, height, weight, body mass index.

As well as the routine monitoring devices worn while undergoing a CPET test, the patients will have 4 capaciflectors placed on them as well. These will be placed using hypoallergenic medical grade tape.

• Over the left precordium
• Over the right precordium
• Under the left axilla
• Under the right axilla

Each practical component of the study setup will be delivered consistently by CI Dr Nick Hayward, Student Doctor Alan Doughty, or cardiopulmonary exercise testing (CPET) technicians once the study becomes established. The patient will then undergo a routine CPET and our monitors will not affect what a patient is asked to do as part of the current CPET protocol. If a patient is unable to finish the CPET then their data will still be included.

Raw CPET data will be exported via a feed from the CPET machine and also from the capaciflectors. A laptop computer provided by the University will receive both data feeds. Simultaneous recordings will be taken from each of the capaciflectors at time zero and then at one minute intervals. These anonymous datasets will be stored on the laptop computer. Once the CPET test is completed, the participant's involvement in the study will have ended.

Anonymised raw data analysis comparisons will be made by the Department of Engineering, University of Southampton, in collaboration with the other investigators of this study. There will be no patient identifiable information in any dataset, yet demographic data and raw CPET acquired data will be held securely on the laptop in line with clinical governance requirements of University Hospital Southampton. Statistical support by Dr Helen Moyses of the Clinical Informatics Research Unit, Southampton, will be provided for data analysis at the final stage.

STUDY SETTING

The study will be a single centre study at University Hospital Southampton. Participants will have been recruited from the patients booked for a CPET test prior to them having major surgery. The study will be conducted in the CPET department in the Day Surgery Unit. This is where the CPET for patients routinely takes place.

Inclusion criteria

• Aged 18 and over
• Able to give informed consent in English
• Able to at least start a CPET test

Exclusion criteria

• Absolute contraindications to taking part in CPET:
• Recent (within 5 days) Acute Myocardial Infarction
• Unstable angina
• Uncontrolled arrhythmia causing symptoms or haemodynamic compromise
• Syncope
• Active endocarditis, acute myocarditis or pericarditis
• Symptomatic severe aortic stenosis
• Uncontrolled heart failure
• Suspected dissecting or leaking aortic aneurysm
• Uncontrolled asthma
• Arterial desaturation at rest on room air < 85%
• Known allergy to medical grade tape