attention problems Pallor Sensitivity to heat Sleep problems Other vasomotor symptoms. Causes Symptoms of OI are triggered by: An upright posture for long periods (e.g. standing in line, standing in a shower, or even sitting at a desk) A warm environment (e.g. hot summer weather, a hot crowded room, a hot shower or bath, after exercise) Emotionally stressful events (seeing blood or gory scenes, being scared or anxious) Return from an extended stay in space, when the body is not yet readapted to gravity Extended bedrest Inadequate fluid and salt intake. Diagnosis OI is "notoriously difficult to diagnose." As a result, many patients have gone undiagnosed or misdiagnosed and either untreated or treated for other disorders. Current tests for OI (tilt table test, autonomic assessment, and vascular integrity) can also specify and simplify treatment. Patients with dysautonomia symptoms can be referred to a cardiologist, neurologist, or even a gastroenterologist for treatment and management. Management Most patients experience an improvement of their symptoms, but for some, OI can be gravely disabling and can be progressive in nature, particularly if it is caused by an underlying condition that is deteriorating. The ways in which symptoms present themselves vary greatly from patient to patient; as a result, individualized treatment plans are necessary. OI is treated pharmacologically and nonpharmacologically. Treatment does not cure OI; rather, it controls symptoms. Physicians who specialize in treating OI agree that the single most important treatment is drinking more than 2 liters (8 cups) of fluids each day. A steady, large supply of water or other fluids reduces most, and for some patients all, of the major symptoms of this condition. Typically, patients fare best when they drink a glass of water no less frequently than every two hours during the day, instead of drinking a large quantity of water at a single point in the day. For most severe cases and some milder cases, a combination of medications is used. Individual responses to different medications vary widely, and a drug that dramatically improves one patient's symptoms may make another patient's symptoms much worse. Medications focus on three main issues: Medications that increase blood volume: Fludrocortisone (Florinef) Erythropoietin Hormonal contraception Medications that inhibit acetylcholinesterase: Pyridostigmine Medications that improve vasoconstriction: Stimulants: (e.g., Ritalin or Dexedrine) Midodrine (ProAmatine) Ephedrine and pseudoephedrine (Sudafed) Theophylline (low-dose) Selective serotonin reuptake inhibitors (SSRIs - Prozac, Zoloft, and Paxil) Behavioral changes that patients with OI can