What is the significance of systolic high blood pressure that drops to normal after a few minutes of sitting?
November 13, 2011 1:02 PM   Subscribe

What is the significance of systolic high blood pressure that drops to normal after a few minutes of sitting?

I am a guy in my 20s. For the past year my systolic blood pressure readings at doctor's visits office have been high (in 130s and 140s; diastolic is normal). The nurses always take these readings immediately after sitting me down.

Through my own experimentation with the blood pressure monitor at my local drugstore, I've noticed that my BP will usually drop to the 120 range after a few minutes of sitting. I've also observed that it fluctuates a lot from day to day.

At my last doctor's visit, the nurse again gave me a high BP reading. When the doctor arrived, I had him repeat the measurement since I had been sitting for a few minutes. Sure enough, it was down about 20 points. He told me that according to standard procedure, in order for the measurement to be valid, the patient needs to sit for 5 minutes beforehand, and acknowledged that the nurses do not follow this standard procedure. He reassured me that it's common for BP to drop like this, and that the second normal reading negates the initial one.

Is there any scientific evidence for or against this assertion? I am curious why my blood pressure behaves differently from most other people (and from the way it used to be), and if it is of potential clinical significance.
posted by wireless to Health & Fitness (9 answers total) 4 users marked this as a favorite
 
I mam not going to look up the research but your physician is right--the most accurate blood pressure is taken 3-7 minutes after sitting. There is no clinical significance to the 20 point drop as it is normal and predicted. Just enjoy your normal BP. And yes, blood pressure normally fluctuates through out the day--much information about this on the web.
posted by rmhsinc at 2:18 PM on November 13, 2011


Hey. (Future) nurse here (fingers crossed!). It's well known that positional changes can affect blood pressure. Many individuals are affected by orthostatic hypotension, wherein their BP drops when shifting from a recumbent to sitting position, or from sitting to standing. I know that's not what's affecting you, just mentioning it as an example of how position can affect BP.

First, I'm not sure exactly what you mean when you say your blood pressure behaves differently from most other people. It sounds like your BP drops after a few minutes of sitting calmly. This is normal and very common. Did I miss something?

I don't have any good links off hand regarding BP changes as related to position, but a quick search brought up this link from the National Dysautonomia Foundation. I can't vouch for them, though. Here is a link to one study investing changes in blood pressure caused by position changes. I'm not sure it quite answers your question - this study addresses the rise in blood pressure seen on standing. Still, it could be a starting point for your own reading/research.

If you'd like to do some searching on your own, you want to use search terms like "positional blood pressure". BP does certainly fluctuate throughout the day, and a diagnosis of hypertension should always be based on a series of readings, not one isolated high reading.
posted by pecanpies at 2:21 PM on November 13, 2011


Best answer: Your physician is correct. Blood pressure is an indirect measurement of your cardiac output in the moment it is taken.

The amount of blood that is put out by the left ventricle of the heart into the body in one contraction (beat) is called the stroke volume. The stroke volume multiplied by the heart rate is the cardiac output.

Low diastolic pressures mean that the heart has the opportunity to have a high end-diastolic volume, which means in between beats, your ventricle can fill completely up and perfuse the arteries feeding the heart muscle as well as send a large stroke volume of blood to the body.

Low systolic pressures indicate that peripheral resistance to the heart's contraction is low--another way, it measures pressures asserted against the heart while it is beating (versus at rest, filling, with diastolic). All kinds of things increase resistance against the flow of blood away from the heart, namely, sympathetic nervous activity like moving around or being nervous about sitting on an exam table.

So if you take a look at my second paragraph there--where Cardiac Output=Stroke Volume x Heart Rate (CO=SVxHR) you can reverse engineer that if you heart rate is elevated, your blood pressure will be, as well, since the SV will increase, increasing the pressures against vessel walls.

Healthy hearts and vessels recover quickly from increases in our sympathetic nervous system, which is why an accurate reading of your blood pressure would reasonably be taken after five minutes of rest--which is the clinical guideline. Your blood pressure changes minute by minute according to the perfusion needs of the body which increase or decrease according to what you're doing. Hypertension is officially diagnosed by three separate readings taken on three separate days after five minutes of rest.

Increased systolic that recovers is as common as milk. Your heart rate responds directly to your body's needs and activities and pathologic states. There are ways that we worry a little more about consistent high diastolics because the heart, and the heart's feeding arteries, aren't getting a chance to fill which means overall poor perfusion and an at risk state for infarction. However, again, diagnostic readings happen after rest, and in a series.
posted by rumposinc at 2:24 PM on November 13, 2011 [5 favorites]


You can read way more than you ever wanted to know - and in excruciating detail! - about BP measurement standards in this article from the American Heart Association. Note the section on Subject Preparation.
posted by lulu68 at 2:41 PM on November 13, 2011


The phenomenon you're observing is, just as your actual doctor claimed, totally normal. Previous answers have spoken about the physiological underpinnings, but on the more immediate level I can point out two probable reasons why your blood pressure is higher when you first sit down. First, your blood pressure is typically higher when you are active. When you first sit down your blood pressure hasn't yet declined to the resting level. Second, you may have a spot of white coat hypertension -- i.e., hypertension triggered by medical anxiety. When you've had a moment to settle yourself in and collect yourself, your blood pressure normalizes. Even if you aren't actively worrying, your body may be experiencing some additional stress until you get your bearings. Having a previous high blood pressure readings can compound this problem. So don't sweat it. Just make sure to warn your health care providers that you need to sit for a few minutes before they take a reading.
posted by reren at 2:51 PM on November 13, 2011


Response by poster: Thanks for the replies. I understand that according to the official guidelines I am not at risk medically. However, I want to play devil's advocate with the contention that this is "normal". Even if it may not be medically risky, the following evidence suggests to me that something unusual is taking place with my body:

1) Prior to this year, this never happened. My BP was usually below 120, even right after sitting down. Something must have changed in my body.
2) I asked a few friends/family members for their BP readings immediately after sitting, and most of them are below 120.
2) Almost every doctor's office I've visited has taken my BP right after I sit down, and the nurses/doctors always express concern at the high BP reading. My employer's health screening uses this method as well. Why would they continue using this method if it's usual for it to overestimate BP by 20 points?

My central point is that I predict that most healthy people would not see their readings in the 130s and 140s, even right after sitting down. What accounts for the difference between people whose blood pressure is normal right away, and those whose blood pressure takes a few minutes to drop to normal?
posted by wireless at 3:21 PM on November 13, 2011


This happens to me, and I am also a guy in my twenties who appears perfectly healthy in most other regards. Mine spikes even more than yours does, and my resting BP was hypertensive most of the time a couple years ago. Now, through a combination of primal eating, supplements, and (I believe least effective) exercise, it's usually normal when I am resting, but still spikes way high at the doc's. The "white coat hypertension" reren spoke, anxiety about having a good reading is exactly what makes it worse. So, thanks for posting, this is very informative.
posted by Earl the Polliwog at 3:29 PM on November 13, 2011


Your follow up questions:
1) You may or may not have had an increase in peripheral resistance in the last year (d/t decreases in daily activity, increases in blood lipids, increases in smoking, who knows). You could have a genetic profile that programs factors that increase your peripheral resistance at your age--plenty of people with healthy lifestyles, healthy weights, young ages develop blood pressure changes. Or, there may have been changes in the way your BP has been measured. Or, you never paid attention the same way you are now. There are truly an amazing array of potential factors for something that your physician, given his/her access to your entire medical history, has deemed benign.
2) Unreliable information gathering and time frames for "sitting down" and measurement. Also, there can be echo effects--my immediate resting BP may be lower if I spent the day in bed versus on my bike. Also, dehydration contributes to lower immediate resting BPs due to decreases in stroke volume (SV). Also, prescription drugs. Again, too many factors, too many different people.
3) Even if in clinical practice everyone is doing it wrong (measuring BP without a resting period), it does not mean there is something pathologic going on with you. It means they are doing it wrong, probably because of time pressures on their end. They continue to do it wrong because they have a lot of BPs to take and education about doing it right did not make an impression. Also, you'll often notice if it reads high, they will then do it right and let you rest.

Your central point: UN-healthy BP is determined by 3 high readings, on three separate occasions, after 5 minutes of rest. This is an evidence-based practice to take into account all potential factors, including a within-normal-limits recovery. If you are concerned about your blood pressure, have a series BP taken and talk to your physician.
posted by rumposinc at 3:54 PM on November 13, 2011 [1 favorite]


2) I asked a few friends/family members for their BP readings immediately after sitting, and most of them are below 120.

Here is your clue. It's possible that, as rumposinc, suggests, these readings are in error, but I would wager that you are suffering from white coat hypertension and that you are getting lower readings when you aren't with a doctor because that factor is no longer in play.

As to why this problem has developed, I'd look to the mind, not the body. You sound worried. Before you weren't, right? There's your explanation. It's a self-perpetuating problem.

This has been an issue for me. I see a cardiologist (not for hypertension, but for a congenital condition), and my doctor often has to take multiple readings to get a "true" measure of my blood pressure. Because my blood pressure is high in the office, but not consistently so, I use a home blood pressure monitor like this one. If you'd like to reassure yourself that your blood pressure is stable, get a machine that takes automatic readings and keep records of your blood pressure every week or so for a few months.

The Mayo Clinic article notes that people with white coat hypertension may be at higher risk for developing actual hypertension, but that treatment isn't warranted unless the hypertension persists at home. If there is nothing otherwise wrong with your heart and you've taken care of all modifiable risk factors (diet, exercise, and smoking habits), then it's very unlikely that you, as a man in your 20s, are suffering from serious heart disease. If you do have risk factors for heart disease that are in your control, like a sedentary life style, smoking or poor diet, that's worth addressing whether or not you have mild or pre-hypertension. Listen to your doctors: you're fine.
posted by reren at 4:47 PM on November 13, 2011


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