Testing of a Valsalva Assist Device (VAD) in Healthy Volunteers Performing a Valsalva Manoeuvre
Condition: SVT; Vagal Bradycardia
MeSH terms: Bradycardia
Study type: Interventional

Summary: 
      A prototype for a Valsalva Assist Device (VAD), which provides resistance to exhalation, has
      been developed and is ready for testing in healthy volunteers. There is a need to ensure the
      device can deliver the required strain and evaluate the physiological response (lowered heart
      rate) when used to deliver a Valsalva manoeuvre (VM) with and without postural modification.
    

Detailed description: 
      The aim of this study is to evaluate the performance of a novel Valsalva assist device (VAD)
      in healthy volunteer and to confirm the physiological effects of a modified VM.

      Specific Objectives:

      To measure and compare peak strain pressure and duration produced using the device compared
      to a standard manometer in supine and modified postures

      To evaluate whether there is a difference in vagal tone (drop in heart rate) in healthy
      volunteers performing a VM using the VAD versus manometer.

      To evaluate whether there is a difference in vagal tone (drop in heart rate) in healthy
      volunteers performing a modified VM versus a standard supine VM using the VAD.

      To evaluate whether there is a difference in vagal tone (drop in heart rate) in healthy
      volunteers performing a modified VM versus a standard supine VM using a manometer.

      The investigators will conduct a single centre repeated measures observational study of use
      of the device to generate a Valsalva strain in a sample of healthy adult volunteers from the
      University of Exeter or RD&E Hospital staff. All participants will be screened for
      eligibility and undergo informed written consent prior to participation. If participants fail
      screening due to abnormal clinical readings or vital signs, the chief investigator will
      review them, any urgent abnormalities (very unlikely) would be reviewed by the chief
      investigator or delegated emergency department doctor as soon as they are discovered.
      Depending on the severity, if treatment is required urgently then they will be treated in the
      emergency department. Otherwise, they will be referred back to their GP. Potential
      participants will be given written information about the study at least 24 hours prior to
      recruitment and interested individuals invited to attend screening, recruitment and testing.

      Potential participants will be invited to express an interest in taking part by responding to
      the trial poster. These posters will be displayed in the medical student common rooms ED
      department notice board. The potential participant contacts the researcher leading the
      practical aspects of the trial by phone or email. Respondents will be asked how they would
      like to receive further information (post, email, and phone) and offered an appointment at
      the Clinical Research Facility (CRF) for screening and written consent if eligible, at their
      convenience but at least 24 hours after receiving the information sheet. Given the simple,
      safe and quick nature of the interventions, participants will be given the choice to take
      part after written consent or to return on another date, whichever they would prefer, to
      ensure minimal visits whilst giving participants further time to consider taking part should
      they wish.

      The VM is an extremely safe, physiological manoeuvre which is used in everyday life (eg
      straining at stool) and has been used in trial conditions and clinical practice many
      thousands of times with no serious adverse events. The investigators will exclude
      participants who could conceivably be at any risk of harm from performing a VM or from the
      use of the device.

      The screening will include 12 lead ECG and physical examination including observations of
      heart rate, oxygen saturations, respiratory rate and blood pressure. Any participants with
      any detected abnormalities, whether they are excluded from participation or not, will be
      informed and referred to their primary care physician as appropriate. All testing will be
      conducted in the clinical research facility (CRF) of the Royal Devon & Exeter Hospital,
      according to a strict trial protocol.

      Test Valsalva Manoeuvres:

      Participants will undergo a total of 4 VMs of the following 4 variations in random order,
      stratified by method of strain generation to ensure balance between the order of manometer
      and device use:

        1. Supine VM using a manometer. Supine Valsalva strain using a manometer visible to the
           participant with a target of 40mmHg for 15 seconds

        2. Supine VM using the device. Supine Valsalva strain using the device connected to
           manometer invisible to the participant but visible to a researcher for 15 seconds

        3. Modified VM using a manometer. Semi-recumbent (at 45 degrees) Valsalva stain using a
           manometer visible to the participant with a target of 40mmHg for 15 seconds followed by
           supine positioning and passive 45-degree leg lift immediately at the end of the strain
           for a further 15 seconds (the modified VM)

        4. Modified VM using the device. Semi-recumbent (at 45 degrees) Valsalva strain using the
           device connected to manometer invisible to the participant but visible to a researcher
           for 15 seconds followed by supine positioning and passive 45-degree leg lift immediately
           at the end of the strain for a further 15 seconds (the modified VM)
    

Intervention name(s): Supine VM VAD; Supine VAD manometer; Modified VM VAD; Modified VM Manonmeter
Intervention type(s): Device; Device; Other; Other
Intervention description(s): Valsalva strain delivered using VAD; supine Valsalva strain delivered using manometer; modified VM using VAD; Postural modified position VM using manometer
Other intervention name(s): Valsalva Assist Device supine; Valsalva Assist Device; Standard (supine) position; Modified VM position
Intervention model: Sequential Assignment
Intervention model description: Four repeated measures in each participant in random order
Masking: None (Open Label)
Primary purpose: Other
Keywords: Valsalva manoeuvre; Vagal tone; Modified Valsalva; Valsalva Assist Device