Blood pressure measurement...

[Externet]

Hi.

The typical sphygmomanometer has always been elusive for me to comprehend how it works, even with 'good' hydraulics knowledge. The inflating bladder and the presence of pressures in an 'arm' counteract somehow and the result is a valid reading, tossing in the mix the sthetoscope... I think.

 

IF a manometer with the proper scale was hydraulically 'connected' to an artery, as tapping a existing/in-use intravenous needle on the patient arm; would such blood pressure be able to be permanently read/displayed/monitored in real time instead of the seemingly archaic process of pumping-ausculting-deflating periodically ?

 

Would such way show the high and low heartbeat pressures as a gauge pointer moving between high and low ?

 

 

[fiveworlds]

I would have imagined you would understand it Externet. I have been trained to use a sphygmomanometer a few years ago so I don't mind telling you. The medical practitioner holds the inflation bulb in their hand. This is a basic pump which fills with air, when the inflation bulb is pressed air is forced into the cuff. The cuff is attached to a specially calibrated pressure gauge which in an aneroid sphygmomanometer is a manometer and there is also a mercury or mercury substitute sphygmomanometer. The medical practitioner checks your antecubital fossa for the artery, the end of a stethoscope is then placed on the artery. The medical practitioner inflates the cuff once keeping an eye on the pressure gauge and listening for thumping sounds called Karotkoff sounds. When the thumping sounds are no longer there the medical practitioner notes the pressure on the gauge and deflates the cuff. When the medical practitioner re-inflates the cuff it is good practice to re-inflate to 20-40 mmHg (Mercury/Substitute) in case there is an auscultatory gap. An auscultatory gap is where in certain patients with heart problems etc the Karotkoff sounds stop, the worst I have heard of is somebody with an auscultatory gap of 60 mmHg. The practitioner then notes when the Karotkoff sounds begin in mmHg this is your systolic blood pressure. When the last Karotkoff sounds stop in mmHg is your diastolic blood pressure.

 

 

Edited April 26, 2016 by fiveworlds

[Prometheus]

IF a manometer with the proper scale was hydraulically 'connected' to an artery, as tapping a existing/in-use intravenous needle on the patient arm; would such blood pressure be able to be permanently read/displayed/monitored in real time instead of the seemingly archaic process of pumping-ausculting-deflating periodically ?

 

Would such way show the high and low heartbeat pressures as a gauge pointer moving between high and low ?

 

 

 

Basically yes: this happens.

 

I gave this site a quick look and it seems accurate.

[Externet]

Thanks, fiveworlds.

Am familiar with the use of the instrument, done it many times after read/asked about the correct procedure to use and read the results, many years ago.

 

What escaped to have clear is the hydraulic/pneumatic-physics part of it, interacting under skin and the Karotkoff logic. Which is perhaps more of an embarrassment to have unclear.

 

Later got the lazy special pushbutton electronic unit that atrophies our brains by stopping thinking as many modern products are aimed. Push button and read.

------------------------------------

 

Thanks Prometheus. So such method exists. But medical equipment on post-operatory monitoring does not use such. The pointer of a manometer gauge would display/log the high and low values for blood pressure, if it was tapped to an artery and worn as a watch at the correct height...

 

Perhaps in a few years patients will get implanted a 1/8" NPT tap to screw the manometer in...

[fiveworlds]

Well I found an article on maintaining an aneroid sphyg http://www.ebme.co.uk/articles/maintenance/343-maintenance-of-an-aneroid-sphygmomanometer

[Prometheus]

Invasive blood pressure monitoring, the way it is currently done in hospital, will never be suitable for home use if that is what you are after. Passing a catheter into an artery is full of risks, and even in hospital having an arterial line qualifies you for closer care.

 

Maybe a technology based on pulse oximetry could be extended to measure blood pressure, though if it was easy to do it would already have been done.

[fiveworlds]

Pulse oximeters fail below a certain heartrate.

[Hendrick Laursen]

Invasive blood pressure monitoring, the way it is currently done in hospital, will never be suitable for home use if that is what you are after. Passing a catheter into an artery is full of risks, and even in hospital having an arterial line qualifies you for closer care.

 

Maybe a technology based on pulse oximetry could be extended to measure blood pressure, though if it was easy to do it would already have been done.

 

Agreed.

Rupture of arteries cause serious problems, and intra-arterial injection is not a very common medical procedure.