I check my BP every other day on average - my specific numbers are not at issue here - but instead the method. Like many, the reading at my physicians office and my at-home readings are not always the same - close but not exact. The difference however is enough to change my category from normal to borderline hypertensive. I've calibrated my sphygmomanometer with his numerous times.

My own at-home readings can vary due to a variety of influences - i.e. the angle I hold my arm, how far below the level of my heart it lies, if I tense the upper arm during the process or simply don't completely relax my arm, etc. This is not to mention the fact that if I sit for at least 10 minutes quietly and then take it there is yet another variation of the reading that is yielded.

I've thought long and hard about the current method which is the standard for evaluating blood pressure. And recently even more so since I read an article written by an doctor who feels the target numbers for healthy BP should be more like 115/75. I see a pattern with BP that seems to emulate the trend to keep lowering the numbers with cholesterol. Unlike cholesterol testing I feel the current method of checking BP is seriously flawed, and perhaps even totally irrelevant.

I submit that checking the pressure of "fluid" that courses through a given "hose" by pinching the outside of the hose to cause it to collapse and stop the flow of fluid does not yield the internal pressure that the fluid is experiencing - and the pumping mechanism pushing the fluid - but instead the collapsibility of the hose with that fluid coursing through it at the unknown pressure.

The collapsibility of the hose is influenced by the hoses ability to resist collapsing - diameter, thickness and rigidity of the hose itself as well as the internal pressure contributed by the fluid. In the case of the upper arm we also have the varying overall tone and density of the flesh and muscle that must be compressed as well. All of these contribute to the reading if we used the pinch method employed in modern BP testing.

If you look at your own automobile, oil pressure is established within the system - internal of the hoses and pumping mechanism, not by the pressure exerted outside the system to resisting collapsing the hose. If you applied the current BP testing methods to your own automobile you would get varying readings dependant upon which hose you chose to pinch. If you chose a old worn hose I you would get one reading and if you chose a newly replaced hose, another reading. The medical community needs to find a better method of testing BP IMHO. Perhaps a device similar to a hypodermic needle which is connected to a pressure sensing device that truly reads the pressure the blood and heart is experiencing.

I had this conversation with my physician over a year ago and he dismissed it by saying that it doesn't matter. The medical community understand the baseline values that are healthy.

BP meds are the most prescribed meds in the USA. If the ideal numbers go down to 115/75 there will be a host of new scripts written for people who previously were thought to be in the healthy range and those who were thought to be borderline hypertensive will suddenly find themselves far over the line. I believe that current BP testing needs to be re-evaluated as well. If the evaluation method is so flawed as to not be able to provide absolute accurate reproducible numbers regardless of setting, angle of arm, etc, then lowering the target is irrelevant.

I have often thought that the method used for getting BP has a lot of room for error in it...cuff position, size and shape of subjects arm, tightness of cuff before inflation/choice of cuff size, subjective bias of observer etc. and all of that is beyond the variations that individual musculature and arterial thickness might induce.

There are quite a few studies in Pubmed that cast some degree of doubt on the accuracy of the current method of BP measurement, especially in subjects with obese/oversize arms.

The problem is made worse by those of us with arms that don't fit in the 'Standard' cuff, every time I go to the doc, they get out the standard cuff, roll up my sleeve, and then say "oh, this isn't going to work", and every once in a while, they get a bigger cuff, but most of the time they wing it with the standard one, so I've always questioned the numbers they come up with. I can't seem to decide though if a cuff that is too small will read low or high?

At home I have a cuff that fits, and I regularly check my BP as well. For the most part, it's usually within a given range and I can document with BP the times of stress, etc. but that's after doing it for a while and getting a routine down. Not sure if my numbers are 100% right but I'm looking for the trends more than the actual numbers. Every time the doc takes it, they say it's a bit high, but I'm thinking that's the "white-coat hypertension"

OK.. we have quite an eclectic group on this forum. Those who have mechanical/technical background that overlaps their health/fitness knowledge. Is there a better way to accuratley and consistantly check BP?

I personally don't see a method that would work that isn't a bit more invassive than the current practices. What about ultrasonics? Or a combination of two technologies? Any thoughts?

You can measure rate of flow via ultrasound from the outside of a pipe. If you knew the diameter you could calculate pressure.

Well you can get a measurement of diameter from an ultrasound. Of course one is taking a "random" slice though the artery and being sure one has a slice truly perpendicaular to the long axis of the pipe and therefore a true diameter and not some oblique slice....is non-trivial.

A lot of the home bp test kits now use the wrist. Having used both types, upper arm and wrist I find that the latter produces more consistent results and is less apt to produce varying results based on position of arm and whatnot.

regardless of the efficacy, all the data on which blood pressures are defined as bad are based on epidemiologic studies taht use the same test. So even if it is flawed, and the actual value is off, doesn't matter. The data would still apply. Besides, isolated outlier values and variances don't matter, you are looking for trends. If you consistantly have an elevated trend, then you have a problem based on cohort studies and the like.

Most borderline hypertensives are prescribed lifestyle modifications rather than pills.

I can systematically elevate my dyastolic and systolic values by as much as 10% to 15% by simply hanging my arm lower or tensing my arm. When my MD takes my BP he has me sit on the exam table. I am already 7" taller than him and sitting on the table puts my arm on what would probably be a ~20 degree slope. That changes the values. I respectfully disagree. I hardly think it doesn't matter. Someone who is 120/80 and during an exam, simply with the twist of an arm, elevates it to 135/90 will most likely be suggested a mild prescriptive by a well meaning conservative physician.

Another thing is the level of pressure applied to the stethascope. It changes what you hear dramatically. There are just too many variables at work here for it not to matter.

How about taking a temperature... why not just use the back of the hand on the forehead? Because while you may be able to tell if a person has a temperature or not, you can't tell to waht degreee with any accuracy.

It might matter if you have big arms.

Lancet. 1982 Jul 3;2(8288):33-6.
Error in blood-pressure measurement due to incorrect cuff size in obese patients.

Maxwell MH, Waks AU, Schroth PC, Karam M, Dornfeld LP.

Trained nurse-specialists obtained 84 000 blood-pressure measurements in 1240 obese subjects using cuffs of the three standard adult sizes in a randomised order. The differences in readings between the three cuffs were smallest in non-obese subjects and became progressively greater with increasing arm circumference (AC) in the obese population. The regular cuff (12 X 23 cm) showed the greatest bias in relation to AC. Formulae and a table have been derived to correct the measurement error caused by cuffs of inappropriate size at various ACs. The reported high prevalence of hypertension in obese subjects may be greatly overestimated.

J Hypertens Suppl. 1989 Dec;7(6):S60-1.
Is early diagnosis of hypertension a function of cuff width?

Arcuri EA, Santos JL, Silva MR.

This study followed blood pressure in 11 subjects 5 years after slight or established hypertension had been revealed using a cuff of the correct width (appropriate to arm circumference); at that time, the use of a standard-width cuff (12 cm) had shown a blood pressure within the normal range. For the present study, blood pressure was determined indirectly under very strict conditions so that a faithful comparison between the readings with both cuffs could be achieved. An important underestimate of blood pressure was detected in thin arms when the standard width cuff was used. The present measurements showed a consistent increase in blood pressure with standard-width cuff readings, confirming the hypertension that had been identified using the correct cuff width 5 years previously. These results support our previous hypothesis that early diagnosis of hypertension can be masked by the standard-width cuff, particularly in lean persons.

There's no epi data on back of hand temperature testing

White coat phenom, improper technique (be it positioning, cuff size selection, etc.) are all known errors in taking blood pressure. I don't know many people that write scripts on a single elevated BP, its usually, like I mentioned, based on trends of combined home and office measurings. Besides....

"Individuals with a systolic blood pressure of 120–139 mmHg or a diastolic blood pressure of 80–89 mmHg should be considered as prehypertensive and require health-promoting lifestyle modifications to prevent CVD."

Thats straight from JNC7. Everyone and their dog writes based on those suggestions. Pre-hypertensives get diet and exercise unless they are diabetics, then they MIGHT get an ACE or ARB. Additionally, goal bp for non-diabetics is under 140, even after medication. Hope this helps.

I saw this in action the other day at the Dr.'s office.

After convincing her that the 'standard' cuff was not going to cut it, the nurse who was probably 5'4" took my BP using the large cuff with me sitting on the exam table so given the differences in height, my arm was probably at least 45 degrees below horizontal. Her reading, 130/72. A few minutes the doc who is about 5'10 came in and took it again and measured 110/68. This time my arm was probably 20 degrees below horizontal.

I have been taking my own BP every morning for the last several months and my average is 117/70 but my automatic wrist cuff contains a sensor that prevents it from working unless your arm is in the correct position.

He commented that his male patients always had higher readings when the nurse took it than when he did and ascribed this to gender differences.

I told him it was more likely that his nurse just needed a stepstool...

I love the title of this first study:

Hum Hypertens. 2003 Jun;17(6):389-95.
Arm position and blood pressure: a risk factor for hypertension?
Mourad A, Carney S, Gillies A, Jones B, Nanra R, Trevillian P.

Department of Nephrology, John Hunter Hospital, Hunter Region Mail Centre, NSW, Australia.

The objective of this study was to re-evaluate the effect of arm position on blood pressure (BP) measurement with auscultatory and oscillometric methods including ambulatory blood pressure monitoring (ABPM). The setting was the hospital outpatient department and the subjects chosen were normotensive and hypertensive. The effect of lowering the arm from heart level on indirect systolic BP (SBP) and diastolic BP (DBP) measurement as well as the importance of supporting the horizontal arm were measured. In the sitting position, lowering the supported horizontal arm to the dependent position increased BP measured by a mercury device from 103+/-10/60+/-7 to 111+/-14/67+/-10 mmHg in normotensive subjects, a mean increase of 8/7 mmHg (P<0.01). In hypertensive subjects, a similar manoeuvre increased BP from 143+/-21/78+/-17 to 166+/-29/88+/-20 mmHg, an increase of 23/10 mmHg (P<0.01). Combined results from normotensive and hypertensive subjects demonstrate a direct and proportional association between BP (SBP and DBP) and the increase produced by arm dependency. Similar changes and associations were noted with oscillometric devices in the clinic situation. However, supporting the horizontal arm did not alter BP. Of particular interest, analysis of 13 hypertensive subjects who underwent ABPM on two occasions, once with the arm in the 'usual' position and once with the arm held horizontally for BP measurement during waking hours, demonstrated changes comparable to the other devices. The mean 12-hour BP was 154+/-19/82+/-10 mmHg during the former period and significantly decreased to 141+/-18/74+/-9 mmHg during the latter period (P<0.01). Regression analysis of the change in SBP and DBP with arm position change again demonstrated a close correlation (r(2)=0.8113 and 0.7273; P<0.001) with the artefact being larger with higher systolic and diastolic pressures. In conclusion, arm movements lead to significant artefacts in BP measurement, which are greater, the higher the systolic or diastolic pressure. These systematic errors occur when using both auscultatory and oscillometric (clinic and ABPM) devices and might lead to an erroneous diagnosis of hypertension and unnecessary medication, particularly in individuals with high normal BP levels. Since clinical interpretations of heart level vary, the horizontal arm position should be the unambiguous standard for all sitting and standing BP auscultatory and oscillometric measurements.

PMID: 12764401



J Hum Hypertens. 1999 Feb;13(2):105-9
Arm position is important for blood pressure measurement.
Netea RT, Lenders JW, Smits P, Thien T.

Department of Internal Medicine, University Hospital Nijmegen, The Netherlands.

AIM: To test the effect of positioning the arm on the arm-rest of a common chair, below the officially recommended right atrial level, on the blood pressure (BP) readings in a group of out-patients. PATIENTS AND METHODS: A group of 69 patients (58 hypertensives; 39 males; mean +/- s.d. age 54.1 +/- 16.0 years) participated in the present study. BP and heart rate values obtained in each of the following two positions were compared: (1) sitting with the arms supported on the arm-rests of the chair and (2) sitting with the arms supported at the level of the mid-sternum (the approximation of the right atrial level). BP was measured simultaneously at both arms, with a mercury sphygmomanometer at the right arm and with an automatic oscillometric device at the left arm. RESULTS: Both the systolic and diastolic BPs were significantly higher (P < 0.0001) when the arm was placed on the arm-rest of the chair than at the right atrial level. The same differences +/- s.d. in BP between the two positions were obtained with both measurement techniques: 9.7 +/- 9.4 mm Hg (systolic) and 10.8 +/- 5.8 mm Hg (diastolic) with the mercury sphygmomanometer and respectively 7.3 +/- 8.9 mm Hg and 8.3 +/- 6.0 mm Hg with the oscillometric device. No difference in the heart rate was found between the two positions. CONCLUSIONS: Placing the patient's arms on the arm-rest of the chair instead of at the reference right atrial level, BP measurement will result in spuriously elevated BP values. This may be of great importance for the diagnosis and the subsequent treatment decisions for patients with hypertension.

PMID: 10100058


Clin Cardiol. 1987 Oct;10(10):591-3
Arm position as a source of error in blood pressure measurement.
Mariotti G, Alli C, Avanzini F, Canciani C, Di Tullio M, Manzini M, Salmoirago E, Taioli E, Zussino A, Radice M.

Istituto di Scienze Biomediche Bassini, University of Milan, Italy.

The present study was designed to assess the value of correct positioning of a patient's arm when measuring blood pressure (BP). A total of 181 subjects were examined, 141 hypertensives on treatment, 25 untreated hypertensives, 15 normotensives. All the subjects underwent three BP measurements after a 5-min resting period in supine position. Then two BP readings were recorded in standing position with the arm either positioned by the patient's side or supported passively at patient's heart level. Average systolic BP (SBP) in standing position were 144.6 +/- 20.2 mmHg with the arm at the side and 136.4 +/- 21.1 mmHg with the arm at the heart level (p less than 0.001); average diastolic pressures were 99.0 +/- 12.0 mmHg and 90.2 +/- 12.3 mmHg (p less than 0.001), respectively. A fall in SBP greater than or equal to 20 mmHg from the supine to the upright position was detected in 18.2% of cases when measurement was performed at heart level; such a reduction was inapparent in two-thirds of cases when the arm was placed at the patient's body side. Incorrect positioning of a patient's arm during BP measurements in standing position leads to overestimation of BP values and masks the presence of postural hypotension.

PMID: 3665216