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Life Sciences => Physiology & Medicine => Topic started by: FuzzyUK on 30/10/2009 22:35:58

Title: Why does blood pressure vary with position or posture?
Post by: FuzzyUK on 30/10/2009 22:35:58

When I lie on my right hand side, my systolic blood pressure reading is considerably lower (to the tune of 20 points) than if I lie on my left hand side.  Is this normal? My doctor is unable to come up with a reason.


[PLEASE ENSURE THAT YOUR THREAD TITLES ARE PHRASED AS QUESTIONS, IN LINE WITH OUR FORUM POLICY. THANKS. CHRIS]

Title: Why does blood pressure vary with position or posture?
Post by: chris on 31/10/2009 09:16:33

How are you measuring the blood pressure, and are you lying on the arm in question when you make the measurement?

Chris

Title: Why does blood pressure vary with position or posture?
Post by: RD on 31/10/2009 10:03:34

Unlike the blood pressure cuffs designed for the upper arm, some of those dodgey wrist-cuff devices (http://www.dableducational.org/pdfs/september05/051-05_Wrist_device_inaccuracy_JBP_Monit_May2005.pdf) are designed only to be used on the left wrist. If used on the right wrist it could give a false value.

Quote

What are the pros and cons of the digital monitor?

A disadvantage of the digital monitor is that the accuracy is changed by body movements or an irregular heart rate. In addition, the monitor requires batteries. Some models are designed for use with the left arm only. This may make them hard for some patients to use.

http://familydoctor.org/online/famdocen/home/common/heartdisease/treatment/128.html

[Possibly the asymmetry may be due to the sensor to detect the pulse being positioned over the radial artery.
If this is the case then rotating the device 180^o so the display is upside-down may put the sensor in the correct position when used on the left wrist].

Title: Why does blood pressure vary with position or posture?
Post by: Andrew K Fletcher on 31/10/2009 10:19:28

Quote from: FuzzyUK on 30/10/2009 22:35:58

When I lie on my right hand side, my systolic blood pressure reading is considerably lower (to the tune of 20 points) than if I lie on my left hand side.  Is this normal? My doctor is unable to come up with a reason.

[PLEASE ENSURE THAT YOUR THREAD TITLES ARE PHRASED AS QUESTIONS, IN LINE WITH OUR FORUM POLICY. THANKS. CHRIS]

Will give this a test tonight in bed and report back if mine is the same. Thanks for the post.

Andrew

Title: Why does blood pressure vary with position or posture?
Post by: FuzzyUK on 01/11/2009 08:24:53

Quote from: chris on 31/10/2009 09:16:33

How are you measuring the blood pressure, and are you lying on the arm in question when you make the measurement?

I've noticed this phenomena now for several months and I'm careful to make sure I don't lie on that arm when measuring. One thing I suspect is pressure on the heart by another organ when lying in a certain position. The only other thing that raises my BP is if my trouser belt is done up too tight round my waist, but I make sure that's loose when I do any measurements.

The instrument used is a Lloyds Pharmacy cuff BP meter (They are good value for a tenner).

Title: Why does blood pressure vary with position or posture?
Post by: Andrew K Fletcher on 03/11/2009 16:57:30

Ok this is what I found when measuring bp and posture.

Laying on left side on a horizontal bed lowered bp vy 2-3 point on systolic and diastolic compared to laying on right hand side. Arm was measured after 5 minutes or more laying flat and arm was allowed to rest on uppermost side while being measured.

Laying on a five degree head up tilted bed (inclined therapy)

Resting on right hand side compared to resting on left hand side showed systolic blood pressure 2-3 points above LHS rest and 8 points diastolic above LHS rest.

Hope this helps

Andrew

Title: Why does blood pressure vary with position or posture?
Post by: rosy on 03/11/2009 17:02:49

All sorts of things seem to affect blood pressure measurements. Last time I had my blood pressure measured, I had noticeably different readings depending on whether I did or didn't have my legs crossed (a nurse at my GP's surgery, so probably not an instruments issue..).