Not my field, so consider this mere speculation of an engineer.

Blood pressure does respond to position, true enough. Seems hard to believe, but even something like sitting with legs crossed raises blood pressure, compared with legs uncrossed. Also, keeping the arm, from which you are measuring blood pressure, elevated to the same height as your heart, as opposed to below or above. Which intuitively, makes sense. (Same as water pressure in a building. The upper floor(s) will experience lower pressure than the ground floor, unless you introduce separate pressure regulators on every floor, to compensate for the effect of gravity.)

If you lie on your left side, your heart is moving the weight of the entire right side of your torso, up and down. To keep a good rhythm, that requires more work of the heart, hence higher blood pressure. Plus, to make the reading a little higher still, the blood pressure sensor on the left arm is now lower than the heart.

Lying on your right side, the heart is not carrying as much weight. Plus, to make the reading a little lower still, the blood pressure sensor on the left arm is now higher than the heart.

Not sure why lying on your back should be a problem. I never heard that to be an issue. I would expect, lying on your back should reduce blood pressure the most? As your arteries are compressed by gravity the least, and your heart is not struggling to move a lot of body weight? And, the blood pressure sensor is now about the same height above ground, as the heart. That should be the lowest reading, as well as the most accurate, I would think. In a hospital setting, however, patient lying in bed, I would expect it is more difficult for the nurse to strap the blood pressure monitor on the patient's arm, if he/she is lying on his/her back.

Dear Moshe Rogosnitzky,

To make a diagnosis of hypertension it requires the measurement taken in sitting positions with patients being relaxed. Measurements to be taken in the both arms. The measurement showings higher recording is the actual BP. Generally BP are taken in 3 separate occasion spreading over a week. This is how we know what is going on with BP.

The highest reading in what ever arm and position the person is, should be taken as measures of real BP.

So the answer is, your reading at the above mentioned situation will have no value.

There can be many reasons, why such differences should occur including errors in measurements, after changing the position .(beyond the scope of of describing here).

Measuring BP is very skill and challenging aspect in clinical parctice. Allthogh look simple and done by various professionals and non professional s.

"I would expect it is more difficult for the nurse to strap the blood pressure monitor on the patient's arm, if he/she is lying on his/her back." Right.

Because the pressure and flow in vessels do wow down in lying on back position. As we are aware of the simple point in 1st Aid, in an emergency situation after checking the patients breathing and bleeding is ok we turn patients to his/he left facing down wards in breeging position, split legs apart for a best air flow. Albert Manfredi.

"There can be many reasons, why such differences should occur including errors in measurements, after changing the position" right.

Chowdhury/Chaudhury Meshkat Ahmed.

Dear Moshe Rogosnitzky,

At a times in critically sick patients, you may have to monitor the patients, in the way you have mentioned. But in those casrs BP is monitored continously by automated non invasive BP, which is attached to the monitor and are constantly monitored. Many a time in such case, recordings show fluctuations of BP ( mostly due to technical csuses). In those cases BP is measured manually to get the BP. Allthogh in some situations BP can be monitored invasively by an invasve arterial catheterization when it is much needed.

Generally the highest BP rcorded is the real BP, meaning your patience BP in supine position to be taken as the true value. And still if are interested to know the BP in the right postion you have to readjust the total measuring procedure. As Albert Manfredi rightly mentioned the measring instrument should be kept at the level of heart.

Yes much morre engineering components are there in cardiac patients_civil, mechanical, elctrical.

Dear Fatema the properly trained CCU or ICU nurses are best in this regards.

In your country you have MSc in csrfiac nursing and they do an excellent job for the cardiovascular patients.

As we all know that Blood pressure is mainly regulated by short term( Baroreceptor reflex) and long term regulatory mechanism. Among the all position that includes sitting , supine , Lateral and supine with crossed leg or uncrossed legs. In standing position . BP will be slightly lower than supine position , because of effects of gravity on flowing blood lead to decrease venous return to heart that causes decrease stroke volume and ultimately decreased CO and decreased BP, this is physiological responses is just opposite of Supine position ( increased BP).Left lateral postion having more BP than right lateral position .usulally thers is no BP change seen from sitting to supine or vice- versa. Maximus systolic blood pressure noted in Supine position but Diastolic blood pressure showed slight variations.Racial variation is also observed . BP change to postion guide us to judicious use of Fluids any maneuver and Medication to improve the patient Safety.

I would sugest to read my article on PubMed author Iosa D. about the effect of Chagas´¨disease on arterial blood pressure . and also my article study of the Autonomic Nervous System, on Google. Sincerely your Dr Daniel Iosa MD PhD

Definitely there is relationship between Bloop pressure and positon changes . that why we used to raised the leg up in vasoovagal attack ,a person experienced.