Many of the medications that psychiatrists prescribe can affect the body’s ability to respond to changes in blood pressure that occur naturally when you stand up, after being in a sitting or lying position for some time – orthostatic vital signs are taken as part of an evaluation of that risk.
Heart rate and blood pressure should be obtained when lying down, when sitting up, and after standing.
Recall that you should be using a cuff that wraps around your upper arm and is not too tight or loose (it is important to have the right size of blood pressure cuff). You can read more about how to use a blood pressure cuff and which ones are accurate in this blog post. The cuff should be located at the same height as your heart.
- Record lying blood pressure and heart rate.
- Sit up straight and check your blood pressure again, as soon after you sit up as possible. You may have to have something to rest your arm on so that the blood pressure cuff remains at the same height as your heart when you sit up. Record sitting blood pressure and heart rate.
- Finally, stand up and record your blood pressure immediately after standing up and then, again, five minutes after standing up. You will definitely need to have a shelf or something else to rest your arm on when you take the blood pressure.
These measurements may detect susceptibility to orthostatic hypotension (OH) – which is a drop in blood pressure that may cause fainting or dizziness.
A drop of ≥20 mmHg (>30 mmHg if you have hypertension) in systolic pressure (the larger number) and/or a drop of ≥10 mmHg in diastolic pressure (the smaller number) is considered diagnostic of OH. An increase in the heart rate, even if there is not a big drop in blood pressure may be a sign of OH.
These numbers should only be used as rough guides and should not be considered definitive proof of the source of dizziness or fainting, discuss the findings with your doctor.
Syncope in adults: Clinical manifestations and initial diagnostic evaluation. Up to Date online. 2022.