NCT02083029

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

• Status: Completed
• Phase: N/A
• Study type: Interventional
• Enrollment: 24 (actual)
• Sponsor: Hull University Teaching Hospitals NHS Trust · Other Government
• Sex: All
• Age: 18 Years – 85 Years
• Healthy volunteers: Accepted

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.

Conditions

• Asthma
• Syncope

Interventions

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

Timeline

• Start date: 2013-01-01
• Primary completion: 2014-01-01
• Completion: 2014-01-01
• First posted: 2014-03-11
• Last updated: 2014-03-11

Locations

1 site across 1 country: United Kingdom