consent therefore needs to be considered. The test itself has a good safety record, but issues around rare complications such as mechanical failure of the apparatus, the risk of stroke if carotid sinus massage is performed, the risk of seizure and complications of drugs administered (eg ventricular tachyarrythmias with isoprenaline) are important. The test is used to provoke syncope in those susceptible, although may be aborted if pre-syncope states occur. Some regard pre-syncope as not diagnostic. In the context that the test is often used in the work up for temporary loss of consciousness, it is important to be aware that is not unknown for patients to manifest definitively their diagnostic epilepsy or cardiac tachyarrythmia during the test.
Common current protocols involve the patient resting supine for at least 5 minutes, being tilted at up to 70 degrees for a minimium of 20 minutes and with GTN spray sublingually being administered. Often carotid sinus massage is done during the test. Testing should be done with continuous ECG and blood pressure monitoring. Older protocols used isoprenaline infusions and non-continuous or invasive blood pressure monitoring and except for rare indications are likely to be less sensitive or specific than current protocols.