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Automated Blood Pressure Monitors

Thu, 14 Nov 2013|

FireEMS Edtior Mike McEvoy discusses some considerations when taking a patient's blood pressure using an electronic blood pressure device.

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Transcript

[MUSIC] Hi, welcome to Fire Engineering Training Minutes, I'm Mike McEvoy. Today, we're gonna talk about measuring blood pressure with a noninvasive or an electronic blood pressure measuring device. Automated blood pressures or non-invasive blood pressures are now included as a skill in the EMS educational standards for EMT level providers and above. So, using this technology. Electronic blood pressure measuring device. We're gonna place a cuff on the patient, and measuring the cuff is somewhat of a challenge for accuracy. And so what we would like to see is a cuff whose bladder actually covers 40% of the circumference of the arm which is a difficult calculation to do and can be simplified by selecting a cup who's width actually covers 2 3rds of the distance between the shoulder and the elbow. Or, if you were measuring blood pressure on the lower arm, for example, in a patient who is extremely obese, you would coat, choose a cuff that covered 2 3rds of the distance between the elbow and the wrist. In this patient, we selected a cuff that width is 2 3rds of the distance between his shoulder and his elbow. We're gonna move the shirt so that the cuff is on skin. Place the bladder around the arm and secure the cup so that it's snug on the patient's arm. Now the next piece of measuring blood pressure, regardless of the device that you're using, is the location of the extreminy that you're measuring in relationship to the heart. You want the cuff to be at mid-heart level. So in this case we'll ask the patient to relax his arm, down at his side. The cuff is now at mid-heart level. If the patient had his arm above mid-heart level, you would get an excessively low blood pressure. We'll show you that later. If it was below heart level, as if he was laying on his side in the street and you were to choose an arm that was under the patient, you would get a higher blood pressure than is actually in the patient. So with the arm at mid heart level, we're gonna push the blood pressure activation switch on the monitor. We'll see the cuff actually inflate. Because the patient has a pulse oximeter that's on the same extreminy as the blood pressure cuff, we're gonna lose our pulse oximeter wave form on the monitor during the time the cuff is inflated. The cuff now is measuring the heart rate of the patient and it's measuring the mean arterial pressure. And this is important because there are times when protocols will suggest that you obtain a manual blood pressure and compare it to the cuff, the electronic cuff. And, in fact, the methodology that these machines are using to obtain this blood pressure that you now see on the screen, is to measure the mean pressure and to measure the heart rate. You notice that it's displayed a heart rate that it's gotten from the blood pressure cuff, not from the oximeter. And it displays a mean in the lower left hand corner of the screen. Those two are actually measured numbers. So, in this case, the mean pressure of the patient is 99, the normal mean pressure for you or I would be between 70 and 105. The device, then, uses the mean pressure that its obtained and the heart rate to calculate the systolic and the diastolic pressure. And it does that by using a formula that determines how long the patient's cardiac cycle has spent insistently and how long its spend in diastole. And then depending on the manufacturer of the device that uses a technology that we refer to in medicine as a SWAG or Some Wild-Ass Guess to calculate a systolic and a diastolic pressure. Hence, if you have a protocol that says check the manual pressure and compare that to the electronic blood pressure. This systolic and diastolic are merely calculated numbers. What's actually being measured and really what you should treat, is the mean pressure on the device. And you'll notice, many paramedic protocols and many hospital protocols focus on mean pressure and that's because that's what's actually measured with the device. Now let me show you what would happen if we were to elevate the arm above the level of the heart. We'll take the oximeter off and we'll ask the patient to raise his arm up in the air. And now we'll cycle the blood pressure cuff again. Again the cuff is pumping up, its putting air into the cuff and measuring the mean pressure and the heart rate as it deflates. You notice the numbers cycling down. And with his arm above the level of the heart, we're going to obtain a pressure that's considerably lower than 126 systolic that we had with his arm at mid-heart level. So it's important to keep those considerations in mind when you're measuring pressure with an electronic device. Lastly, we're finished with using equipment on the patient [SOUND] and an important asset of taking care of your equipment and not contaminating patients from one patient to the next with your equipment, is to decontaminate the equipment. And before you put a device like this away, you're gonna use some sort of a cleaning or disinfectant wipe to clean the blood pressure cuff and the cables off. Because we're using a wipe that is a quantrinary ammonia compound. The kind of thing that the EPA advises to be used on cleaning medical equipment. We're gonna put gloves on. You notice that gloves were not necessary to take a blood pressure on a patient. Gloves are probably excessively used and you can read a little bit about that on our Fire EMS website in the in above ward section are infection control specialist Cathy West has written quite a bit about misuse of gloves by EMS providers. With these gloves we're protecting our hands from the disinfectant that we're using on the blood pressure cuff and then we'll wipe down the cable that we use and after the cuff has dried up we'll store it back in the device. This is Fire Engineering Training Minutes, I'm Mike McEvoy. Thanks for watching.

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