Syncope, also called fainting, is the loss of consciousness caused by temporary loss of blood supply to the brain, followed by complete recovery. About 40% of people will faint in their lifetime and half of them will first faint as teenagers, around the age of 15. Fainting can be caused by orthostatic hypotension. Otherwise, it can occur for cardiac or neurologic reasons (also called reflex syncope). One type of reflex syncope is vagovagal syncope, which can be further divided into postural syncope (fainting upon standing) and emotional or phobic syncope (fainting due to unpleasant psychological stimuli).
Vagovagal syncope has been attributed to several things, but none have been definitively proven. Some patients have decreased presence of enzymes that mediate blood pressure, like norepinephrine transportase (NET). Some have insufficient circulation in the abdominal cavity. As vasovagal syncope is often preceded by lightheadedness, sweating, weakness, nausea and visual disturbances, it can be difficult to distinguish between VVS and POTS. However, VVS patients often go long periods without OI symptoms, which only occur immediately before syncope. Postural syncope and POTS are also associated with increased rate and depth of breathing in order to meet oxygen needs during these episodes.
Ingestion of 16 ounces of water in five minutes is known to effectively treat OI episodes of all types. It begins to have effect in about twenty minutes. It is important that this water not have solutes; that is to say, it should be pure water. Effects can last for hours.
There are a number of precipitating factors that can induce OI symptoms in susceptible patients. Avoidance is a key treatment modality. These factors include large meals, sudden postural changes, laying down for extended periods of time, environmental heat, alcohol, vasodilators* and sympathomimetic drugs, such as methylphenidate. (*It is worth noting that mast cell disease is inherently vasodilatory).
For both orthostatic hypotension and neurogenic POTS patients, physical maneuvers and compression garments can decrease venous pooling of blood. Increasing both salt and water intake can be helpful to expand plasma volume; 1.5-2L is recommended for adults.
Medications that retain salt and water, such as fludrocortisone, may be tried as well. Pressor drugs with short half lives, such as midodrine and pyridostigmine, are also used in these patients. Droxidopa is used outside of the US. Other meds, such as clonidine, also see some utility. Exercise is also encouraged as a treatment option (will be detailed in a follow up post).
HyperPOTS is often treated with beta blockers. (WARNING: beta blockers interfere with the action of epinephrine and should be used cautiously in mast cell patients). Angiotensin receptor blockers like Cozaar have been used, as has droxidopa. Exercise is likewise suggested for treatment of this patient group.
Water ingestion is recommended for patients with vasovagal syncope. Additionally, physical maneuvers are advised upon the onset of OI symptoms.
Stewart, Julian M. Update on the theory and management of orthostatic intolerance and related syndromes in adolescents and children. Expert Rev Cardiovasc Ther 2012 November; 10(11): 1387-1399.
Benarroch, Eduardo E. Postural tachycardia syndrome: a heterogenous and multifactorial disorder. Mayo Clinic Proceedings 2012; 87(12): 1214-1225.