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Vagal Nerve Stimulation Assessed by the Diving Reflex: An Investigation Into Mechanisms of Asthma Death

Primary Purpose

Asthma, Syncope

Status

Completed

Phase

Not Applicable

Locations

United Kingdom

Study Type

Interventional

Intervention

Simulated dive reflex

About this trial

This is an interventional basic science trial for Asthma focused on measuring Asthma, Death, Mechanism, Syncope, Dive reflex

Eligibility Criteria

18 Years - 85 Years (Adult, Older Adult)All SexesAccepts Healthy Volunteers

Inclusion Criteria:

Syncopal Asthmatics: Asthmatic patients with a history of syncope during asthma exacerbations
Normal Asthmatics: Asthmatic patients on BTS Step 3 treatment (LABA/ICS) with no history of syncope during exacerbations
Normal volunteers: no history of airways disease or syncope

Exclusion Criteria:

• Subjects who are pregnant, or have pacemakers in situ are excluded from this study.
- Subjects with significant cardiovascular disease are excluded from this study.
- Those who are non-English speakers and special groups (i.e. mentally ill, children under 16 years of age, and those suffering from dementia) will be excluded.
- No test will be performed on any subject during an acute worsening of asthma or upper airway infection. If the subject has had an upper airway infection in the last three weeks. Another appointment should be made unless the subject is unwilling to come back, in which case testing should continue. The number of days elapsed since the end of the airway infection should be recorded.
- If the subject smokes: citric acid or capsaicin challenges must be performed at least one hour after the last cigarette has been smoked.
- Subjects taking beta-blockers and calcium antagonists will be excluded from this study. No beta agonists should be taken within 6 hours of starting this study.
- If the subject has taken any over the counter (OTC) cough mixture within the last twelve hours: If the subject is willing to come back another time for challenge testing, another appointment should be made. If the subject is unwilling to return another time, testing should proceed and the medication used recorded.
- If the subject has had any food or drink products containing caffeine or menthol within the last hour. If the subject is unwilling to wait for 1 hour before starting the test, the subject should return another time. If the subject is unwilling to return another time, testing should proceed and the medication used recorded.
- If the participant is currently involved in research, or within 3 months of participation in any type of research, they will be excluded from this study.

Sites / Locations

Hull Clinical Trials Unit, Respiratory academic department

Arms of the Study

Arm 1

Arm 2

Arm 3

Arm Type

Experimental

Arm Label

Syncopal Asthmatic

Non Syncopal Asthmatic

Normal Volunteers

Arm Description

All subject undergo simulated dive reflex, with 30s facial immersion and continuous HR and BP monitoring with Nexfin over a period of 6 minutes.

Outcomes

Primary Outcome Measures

Change in heart rate from baseline

Nexfin and ECG monitoring continuously measuring subject heart rate during dive protocol, over a period of 6 minutes. Beat to beat data is converted into mean HR per 10-second epoch and compared to a baseline value for each subject.

Secondary Outcome Measures

Change in blood pressure from baseline

Nexfin monitoring continuously measuring subject blood pressure (systolic, diastolic and mean arterial pressure) during dive protocol, over a period of 6 minutes. Beat to beat data is converted into mean blood pressure values per 10-second epoch and compared to a baseline value for each subject

Full Information

NCT ID

NCT02083029

First Posted

March 3, 2014

Last Updated

March 10, 2014

Sponsor

Hull University Teaching Hospitals NHS Trust

1. Study Identification

Unique Protocol Identification Number

NCT02083029

Brief Title

Vagal Nerve Stimulation Assessed by the Diving Reflex: An Investigation Into Mechanisms of Asthma Death

Official Title

Vagal Nerve Stimulation Assessed by the Diving Reflex: An Investigation Into Mechanisms of Asthma Death

Study Type

Interventional

2. Study Status

Record Verification Date

March 2014

Overall Recruitment Status

Completed

Study Start Date

January 2013 (undefined)

Primary Completion Date

January 2014 (Actual)

Study Completion Date

January 2014 (Actual)

3. Sponsor/Collaborators

Responsible Party, by Official Title

Principal Investigator

Name of the Sponsor

Hull University Teaching Hospitals NHS Trust

4. Oversight

Data Monitoring Committee

5. Study Description

Brief Summary

The investigators' hypothesis is that dysregulation of autonomic function, as revealed during a simulated dive reflex, may result in an attenuation of the heart rate response to a greater degree in asthmatics who collapse during exacerbations of asthma than that seen in healthy individuals and in asthmatics without a history of syncope. The investigators will test this by assessing autonomic function through a dive reflex protocol.

Detailed Description

Tests of autonomic function are notoriously difficult to evaluate. Here the investigators required a well validated test of the dynamic cardiovascular response to an abrupt stimulus and considered the diving reflex the most reliable and practical. In man, the diving reflex acts as a vestigial reflex aimed at conserving oxygen storage during apnoeic facial immersion. Facial immersion activates a vagally-induced bradycardia and a sympathetically activated alpha-adrenergic peripheral vasoconstriction and hypertension. There are two triggers of the diving reflex, facial immersion in water and breath hold, both of which can impact on heart rate attenuation. Facial immersion can be further delineated into exposure to cold, wetness and pressure.

6. Conditions and Keywords

Primary Disease or Condition Being Studied in the Trial, or the Focus of the Study

Asthma, Syncope

Keywords

Asthma, Death, Mechanism, Syncope, Dive reflex

7. Study Design

Primary Purpose

Basic Science

Study Phase

Not Applicable

Interventional Study Model

Parallel Assignment

Masking

None (Open Label)

Allocation

Non-Randomized

Enrollment

24 (Actual)

8. Arms, Groups, and Interventions

Arm Title

Syncopal Asthmatic

Arm Type

Experimental

Arm Description

All subject undergo simulated dive reflex, with 30s facial immersion and continuous HR and BP monitoring with Nexfin over a period of 6 minutes.

Arm Title

Non Syncopal Asthmatic

Arm Type

Experimental

Arm Description

All subject undergo simulated dive reflex, with 30s facial immersion and continuous HR and BP monitoring with Nexfin over a period of 6 minutes.

Arm Title

Normal Volunteers

Arm Type

Experimental

Arm Description

All subject undergo simulated dive reflex, with 30s facial immersion and continuous HR and BP monitoring with Nexfin over a period of 6 minutes.

Intervention Type

Procedure

Intervention Name(s)

Simulated dive reflex

Intervention Description

All subjects undergo simulated dive reflex, with 30s facial immersion and continuous HR and BP monitoring with Nexfin over a period of 6 minutes.

Primary Outcome Measure Information:

Title

Change in heart rate from baseline

Description

Time Frame

2 minutes prior to facial immersion in water and in 10 second epochs continuously until 3 minutes after facial immersion

Secondary Outcome Measure Information:

Title

Change in blood pressure from baseline

Description

Time Frame

2 minutes before facial immersion and continuously throughout dive protocol, over a period of 6 minutes

10. Eligibility

Sex

All

Minimum Age & Unit of Time

18 Years

Maximum Age & Unit of Time

85 Years

Accepts Healthy Volunteers

Eligibility Criteria

Inclusion Criteria: Syncopal Asthmatics: Asthmatic patients with a history of syncope during asthma exacerbations Normal Asthmatics: Asthmatic patients on BTS Step 3 treatment (LABA/ICS) with no history of syncope during exacerbations Normal volunteers: no history of airways disease or syncope Exclusion Criteria: • Subjects who are pregnant, or have pacemakers in situ are excluded from this study. Subjects with significant cardiovascular disease are excluded from this study. Those who are non-English speakers and special groups (i.e. mentally ill, children under 16 years of age, and those suffering from dementia) will be excluded. No test will be performed on any subject during an acute worsening of asthma or upper airway infection. If the subject has had an upper airway infection in the last three weeks. Another appointment should be made unless the subject is unwilling to come back, in which case testing should continue. The number of days elapsed since the end of the airway infection should be recorded. If the subject smokes: citric acid or capsaicin challenges must be performed at least one hour after the last cigarette has been smoked. Subjects taking beta-blockers and calcium antagonists will be excluded from this study. No beta agonists should be taken within 6 hours of starting this study. If the subject has taken any over the counter (OTC) cough mixture within the last twelve hours: If the subject is willing to come back another time for challenge testing, another appointment should be made. If the subject is unwilling to return another time, testing should proceed and the medication used recorded. If the subject has had any food or drink products containing caffeine or menthol within the last hour. If the subject is unwilling to wait for 1 hour before starting the test, the subject should return another time. If the subject is unwilling to return another time, testing should proceed and the medication used recorded. If the participant is currently involved in research, or within 3 months of participation in any type of research, they will be excluded from this study.

Overall Study Officials:

First Name & Middle Initial & Last Name & Degree

Alyn Morice, MD

Organizational Affiliation

Head Cardiorespiratory Studies Hull York Medical School University of Hull Castle Hill Hospital Cottingham

Official's Role

Principal Investigator

Facility Information:

Facility Name

Hull Clinical Trials Unit, Respiratory academic department

City

Cottingham

State/Province

Yorkshire

ZIP/Postal Code

HU16 5JQ

Country

United Kingdom

12. IPD Sharing Statement

Citations:

PubMed Identifier

25142490

Citation

Morjaria JB, Rowland T, Tailor P, Hyder S, Wright CE, Hart SP, Morice AH. Autonomic dysregulation: a mechanism of asthma death. Eur Respir J. 2014 Nov;44(5):1357-60. doi: 10.1183/09031936.00076414. Epub 2014 Aug 19. No abstract available.

Results Reference

derived

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Vagal Nerve Stimulation Assessed by the Diving Reflex: An Investigation Into Mechanisms of Asthma Death

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