Orthostatic hypotension is the condition when a patient experiences dizziness immediately upon standing after being seated or lying down. The dizziness is due to an immediate drop in blood pressure (aka hypotension). Basically, blood is unable to reach the brain fast enough upon rising and thus the brain is momentarily starved of oxygen, causing the black-out/head rush/dizzy feeling. The drop in blood pressure must be around 20/10 mm Hg to be considered orthostatic hypotension. Normally, when standing up after being down for a period of time, blood pressure increases briefly in order to force blood that has pooled in lower body towards the upper body, and blood pressure increase as it must work against gravity upon sudden standing.
To test for this condition, a patient's blood pressure is measured while he or she is seated or lying down and then his or her blood pressure measured as soon as he or she stands (note: the standing value is measure only after he or she has been sitting/lying for a period of time, say 5 minutes during a doctor's visit). The numbers are then compared. If his or her blood pressure is significantly lower after suddenly standing, then the patient may have orthostatic hypotension.
Causes of orthostatic hypotension may be anemia, low levels of blood (hypovolemia), dehydration, underlying disease, or as a side effect of medication. The occurrence also increases with age. Ways to reduce the symptoms of orthostatic hypotension include:
- Rise more slowly. This gives blood vessels more time to constrict and help return blood from lower extremities to the upper body (especially the brain).
- Breath deep breaths and flex the abdominal muscles while rising. Again, this helps bring more blood and oxygen to the brain.
- Increase their salt intake (but I doubt many people have low sodium levels given the abundance of salt in the typical North American diet. I imagine this recommendation is only for those with already low blood pressures).
- Water, water, water! Stay hydrated. When there is less water in the body, there is less blood (hypovolemia).
- Be careful when standing after eating too as blood pressure is decreased even more when digesting.