A question asked by Lord Na: Why is a sitting blood pressure reading more significant than a standing blood pressure reading?
Whenever my blood pressure is taken by a health professional it is usually done when I’m sitting down. The few times I’ve had it done standing up my blood pressure has been lower (this is good not bad) than when I sit down. However, most technicians insist I sit down when they take my BP. Why?
(Incidently there are no adverse effects when I go from standing to sitting, or sitting to standing–no dizziness).
Top answer:
Answer by Sandy H
Your heart has to work “less” as oppose to “more” when one is standing up.
The heart muscle contracts and expands, just like all other muscles of the human body. So when your sitting the heart is actually working less …. and standing its working more. So, yeah, it would be higher when standing.
Provide your own answer to this question below!
Standardisation is the main reason.
The value of blood pressure readings is their trend over time. As readings may be taken in varying situations it is best to try to ensure that they are comparable as much as possible – that means standardising the procedure. Everyone knows that your last BP would have been measured sitting.
Medics could have decided to standardise on standing – but it would be less reliable because more things can affect you in such a situation. It makes more sense to measure when people are relaxed and comfortable which is more likely when sitting. (its also more comfortable for the technician!).
Everyone should actually have a standing measurement at occasionally, just to check that the response is normal. Your blood pressure might drop briefly but it should come back pretty much to the same (usually very slightly lower) than sitting. In some people it stays significantly lower (by say 20points, this is orthostatic hypotension and is ok as long as you do not get dizzy or faint) or in some people it goes high (orthostatic hypertension) this is rare and should be investigated to ensure there are no underlying causes.
Orthostatic hypotension (not a disease but a symptom) is primarily caused by gravity-induced blood pooling in the lower extremities, which in turn compromises venous return, resulting in decreased cardiac output and subsequent lowering of arterial pressure. For example, if a person changes from a lying position to standing, he or she will lose about 700 ml of blood from the thorax. It can also be noted that there is a decreased systolic blood pressure and a decreased diastolic blood pressure. The overall effect is an insufficient blood perfusion in the upper part of the body.
Still, the blood pressure does not normally fall very much, because it immediately triggers a vasoconstriction (baroreceptor reflex), pressing the blood up into the body again. (Often this mechanism is exaggerated and that is why diastolic blood pressure is a bit higher when a person is standing up, compared to a person in horizontal position.) Therefore, a secondary factor that causes a greater than normal fall in blood pressure is often required. Such factors include hypovolemia, diseases, medications, or, very rarely, safety harnesses.
When measuring BP, an accurate reading requires that one not drink coffee, smoke cigarettes, or engage in strenuous exercise for 30 minutes before taking the reading. A full bladder may have a small effect on BP readings; if the urge to urinate exists, one should do so before the reading. For 5 minutes before the reading, one should sit upright in a chair with one’s feet flat on the floor and with limbs uncrossed. The BP cuff should always be against bare skin, as readings taken over a shirt sleeve are less accurate. During the reading, the arm that is used should be relaxed and kept at heart level, for example by resting it on a table.