Orthostatic hypotension is a decrease in blood pressure when changing from a lying or sitting position to a standing position. This decline is a normal reflex adaptation of blood pressure in response to gravity, but when the decrease is too much, it is pathological. Different problems may be involved: a decrease in the volume of blood in the vessels following an intervention, bleeding or dehydration, lack of circulation in the leg veins, certain medications or damage to the nervous system.
Orthostatic hypotension is characterized by the following symptoms, occurring immediately after standing up:
- visual disturbances;
- a feeling of weakness;
- loss of consciousness.
The diagnosis of orthostatic hypotension is done by a test. The doctor measures blood pressure while lying at rest for more than five minutes, along with the pulse ideally, then as soon as the patient stands up, and again at 1, 3, 5 and 10 minutes. In the case of orthostatic hypotension, there will be a decrease of more than 30 millimeters of mercury (reference unit) in systolic blood pressure at one of these times, or by more than 20 mm Hg for diastolic blood pressure. The variation of pulse will help point towards a cause. Even if the drop in blood pressure is usually immediate, a doctor will continue to measure up to 10 minutes to see how the patient adapts to this drop. Also, in patients with venous insufficiency or varicose veins, orthostatic hypotension may appear in a delayed manner.
Treatment of orthostatic hypotension depends on the rules of prevention. If they are insufficient, medications like heptaminol or midodrine may be used.
Prevention of orthostatic hypotension is often achieved by following a healthy lifestyle, eating well and remaining properly hydrated. Patients need to understand the need to gradually wait before starting the stand up.