Impact of Blood Phobia on Fainting Susceptibility

The purpose of this study is to characterize cardiovascular autonomic function to emotional stimuli (blood-injection-injury phobia \[needle phobia\]) during an orthostatic (upright) challenge in individuals with and without known needle phobia. It is well established that emotional stress can produce hypotensive (low blood pressure) reactions. Interestingly, these hypotensive reactions to venipuncture (even with minimal blood drawn), insulin injections, finger sticks for blood sugar monitoring, dental care, and vaccinations can affect up to a quarter of adults and appear to be uniquely associated with blood-injection-injury phobia rather than other phobias. These hypotensive reactions can ultimately lead to a vasovagal syncope (fainting) response, and lead to increased avoidance of medical and dental procedures as a result of this phobia. Ultimately, this has severe implications on public health and places additional strain on the Canadian healthcare system. Currently, there is limited understanding surrounding the initiation of this response. Additionally, a comprehensive profile of cardiovascular autonomic function during exposure to provoking stimuli during orthostatic stress has not been captured in the literature. We will test individuals with and without blood-injection-injury phobia using our standard approach while exposing them to emotional stimuli. Volunteers (n=20) will be asked to undergo a "tilt test" to assess cardiovascular reflex control and orthostatic tolerance (measured as time to presyncope, or near fainting, in minutes). We and others have previously shown this technique to be reproducible, reliable, and to have high sensitivity and specificity for differentiating persons with differing orthostatic tolerance, or for examining the effects of interventions aimed at improving orthostatic tolerance. Volunteers will undergo the test on two separate days. On one test day (the order of which will be randomized) the volunteer will be shown a series of photos and videos during the upright tilt portion of the test. One day the series of content will consist of blood-injection-injury phobia content and the other day will have neutral content. Cardiovascular measures will be monitored through the test. The study will be conducted in a randomised fashion.