Blood pressure measurement , probably is the commonest investigation done in our patients in the entire field of medicine . It is such a common thing , both physicians and patients fail to perceive it as an investigation . (It indeed is !)
Even though BP is considered as a clinical sign , measuring it requires a device called sphygmomanometer . The BP apparatus has to be properly calibrated with the mercury , the tubing, the bladder , inflation balloon etc need to be perfect.
The following fallacies are noted in the measurement of blood pressure . Some of them are rampant* !
Patient
- Posture of recording
- Anxiety -White coat /Gender
Device
- Cuff width/Length
- Arm circumference
Ocular errors
It is surprising , such an important tool has a scale of 2mm markings which is prone for parallax errors of light with mercury column undulating .
Physician factors*
- Hasty cuff syndrome , Rapid deflation .
- Absent minded recording – Failure to note phase 4 to phase 5 due to inattention
- Failure to hear phase 4 muffling (Aging medico -Auditory insufficiency !)
It is not at all surprising to note, two BP readings rarely match , even if it is recorded by the same person with same machine at the same time !
There are many articles that describe in detail , how to record blood pressure properly. But this article from a relatively unknown journal from Purdue university , tells us most scientifically , what has been taken for granted by the medical community for so long .
Loose cuff hypertension (Link to the journal of Cardiovascular engineering )
How much stiffness is to be applied in the arm for optimal pressure recording ?
What is the incidence of hypertension due to loose cuff ?
Final message
The BP apparatus , though appears as an innocuous machine , the readings that emerge from it determines , how millions of our fellow human beings are going to be labeled ! ( High pressured humans , slaves to anti hypertensive drug marketeers for rest of their life ) .
So , realise how important it is , to measure the blood pressure properly ! Never be casual . . . with this machine .
Experience has taught us , while it is very easy to name an individual wrongly as hypertensive , it often needs Herculean efforts to remove this medical tag from their neck . The reasonings are many .( Academic , non academic and patient factors included )
Finally , in this funny planet it is a personal observation ( Or is it an imagination ?) some men and women tend to enjoy , being referred to as high pressured ! Loose cuff or tight cuff , it simply do not bother them !
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Dr.S.Venkatesan MD 