How to Use a Sphygmomanometer the Correct Way

For sufferers of white coat hypertension — a syndrome describing the anxiety that some feel when approached by a medical professional — knowing how to use a sphygmomanometer to properly check blood pressure can mean the difference between life and death. High blood pressure is what us folks in the medical business call “the silent killer”. Prolonged hypertension can exact severe tolls on cardiovascular health, potentially leading to conditions like heart disease and premature mortality. 

Many sufferers live with the pressure for years without symptoms. For those who live with anxiety and hypertension, managing the anxiety is about as important as managing blood pressure.

Visits to the doctor may not be enough, especially if those visits only crank up your anxiety and blood pressure. The good news for anyone who’s recently learned they suffer from high blood pressure is that measuring blood pressure is straightforward and doesn't require advanced skills or equipment. It's a simple process that anyone can learn with ease.

By the end of this blog, complete with step-by-step instructions, you’ll have everything you need to feel confident you can use a sphygmomanometer to test your own blood pressure.

What's a Sphygmomanometer?

A sphygmomanometer is a medical device used to measure blood pressure. It typically consists of an inflatable pressure cuff that wraps around the upper arm, a pressure gauge (manometer) to measure the pressure within the cuff, and a stethoscope to detect arterial blood flow sounds. This device is widely used in healthcare settings to assess a patient's blood pressure. 

Its primary function is to detect the force exerted by circulating blood against the walls of arteries. This measurement provides valuable insights into a person's overall cardiovascular well-being, including risks for conditions such as hypertension, heart disease, and stroke.

How Does a Sphygmomanometer Work?

Sphygmomanometers are pretty useful tools used to measure blood pressure. We all know that as the heart beats, it pumps blood around the body, and the pressure of your blood is an important metric in all kinds of medical check ups. Checking your blood flow, systolic pressure, and diastolic pressure are highly important to your health. 

Blood pressure cuffs are wrapped around the circumference of the upper arm, targeting the brachial artery, and inflated to well above the expected systolic pressure of the patient—they are then allowed to deflate. 

Once the cuff pressure matches that of the arterial pressure, blood begins to flow past the cuff, creating audible noise called Korotkoff sounds. These are monitored using a stethoscope, and will continue until the cuff pressure falls below the diastolic blood pressure of the patient. 

Blood pressure measurements are documented as "systolic over diastolic". An example may be 120 (systolic) over 70 (diastolic).

 

What Exactly Do I Need to Get Started?

Depending on which model you choose, you may not need to buy anything more, as is the case with the Omron model. If the dial-based sphygmomanometer is more your style, plan to pick-up a good stethoscope too.

As you’ll learn in the next section, you’ll have to measure heart rate as part of the process. You could purchase the cuff, bulb, air-tubes, and dial separately from the stethoscope or you may consider a nursing student kit like the ACU Student Pack.

Medshop Australia packages together products for students to save on a bundle. We even have a deep discount kit, which has all you need to get started at home. There’s no reason you can’t take advantage of those savings, even if you aren’t a student.

Shop student kits now

One thing is for sure, you won’t need a high-end stethoscope like the cardiology stethoscope unless you’re moonlighting as a heart specialist in your free time.

An entry level or classic stethoscope will do.

Shop Medshop Australia's stethoscope inventory now

Do consider a paediatric version if you’ll be setting up to track a child’s blood pressure. That goes for your blood pressure set-up too. Most ship with multiple sizes of cuffs, the only real variable outside of the stethoscope.

 

Preparation for Measurement

Before proceeding with blood pressure measurement using a sphygmomanometer, it's crucial to ensure proper preparation. You could purchase the cuff, bulb, air-tubes, and dial separately from the stethoscope or you may consider a nursing kit. You won’t need a high-end stethoscope like the cardiology stethoscope unless you’re moonlighting as a heart specialist in your free time. An entry level or classic stethoscope like the will do.

This step significantly impacts the accuracy of the readings. Follow these guidelines to prepare effectively:

• Selecting the Right Cuff Size: Begin by choosing a cuff size that fits the patient's arm circumference correctly. Using an improperly sized cuff can lead to inaccurate readings. Refer to the manufacturer's guidelines for determining the appropriate cuff size or measure the patient's arm circumference and match it to the cuff size range provided.

• Patient Preparation: Before taking measurements, instruct the patient to sit comfortably in a chair with their feet flat on the floor and their back supported. Ensure that the patient's arm is positioned at heart level, either by supporting it on a table or holding it up with your own support.

• Environment Setup: Create a quiet and calm environment for the measurement process. Minimize distractions and noise that could interfere with accurate readings. Make sure the room temperature is comfortable for the patient, as extreme temperatures can affect blood pressure.

• Rest Period: Allow the patient to rest for a few minutes before taking measurements. This resting period helps stabilize the patient's blood pressure and ensures more accurate readings. Avoid measuring blood pressure immediately after physical activity or consuming caffeine or nicotine, as these factors can temporarily elevate blood pressure.

 

Step-by-step Procedure for Measuring Blood Pressure with a Sphygmomanometer 

1. Apply the Cuff - Position the cuff around the upper arm, ensuring it's snug but not too tight and align the lower edge of the cuff about an inch above the elbow crease.
2. Inflate the Cuff - Use the bulb to inflate the cuff until the pressure gauge reaches 180 mmHg (millimeters of mercury). As the pressure rises, momentarily blocking blood flow, you should detect the absence of sounds through the stethoscope. Slowly release the pressure (3mm/sec) by turning the release valve counterclockwise.
3. Monitor Heart Sounds - Initially, you'll notice a knocking or tapping sound, known as Korotkoff sounds, as the pressure inside the cuff decreases and aligns with the patient's systolic blood pressure. These sounds signify the onset of blood flow through the constricted artery. 
4. Record the Readings - Note the pressure level on the manometer when you first hear the Korotkoff sound. Record this as the systolic pressure. Continue deflating the cuff until the sound disappears completely; record this as the diastolic pressure.

These two values constitute the patient's blood pressure reading. For instance, if the measurement shows 110 systolic and 70 diastolic, you would express it as "110 over 70" or write it as "110/70 mmHg." The normal blood pressure typically falls within the range of 90/60 mmHg to 120/80 mmHg.

How do I Interpret Data from a Sphygmomanometer?

This is the most straight-forward part of the process, but that doesn’t mean it’s easy. There may be concerning results, making subsequent tests challenging.

Since you can stop worrying as easily as you can stop a train, instead redirect the train of your thoughts to something procedural. Do something like make a grocery list in your head.

Although opinions vary somewhat, in general, a normal test will read 120/80 (systolic/ diastolic).

Readings between 120 and 139 for systolic and 80 to 89 in diastolic indicate possible prehypertension.

If your systolic is between 140 and 150, and your diastolic is between 90 and 99, you may have stage I hypertension.

Stage II hypertension is when your systolic exceeds 160, with a diastolic over 100.

Stage III hypertension is over 180 systolic, and a 110 diastolic or higher.

There are many factors that can give you a false reading. Unless it's 180/110, try not to panic over one high reading. Even then, perform at least one retest.

If you’ve been engaged in a robust activity, like working out or playing sports, it may be higher. If you’ve been eating salty food, consuming stimulants (coffee, ADD medication), it will be higher than normal.

Adjust the cuff and take another reading.

If you wait a few hours and it doesn’t come down from a one-off, you may feel more comfortable after contacting a medical professional.

Low readings may mean you need to retest, but if they’re accurate, you should only worry if your physician has advised you to do so or if you feel lightheaded. If you’re concerned in any event, don’t be silly. Contact your physician.

What's Better—Digital or Manual Sphygmomanometers?

There are several types of blood pressure monitors on the market, from clinical wall-mount systems to much simpler wrist monitors, with everything in-between.

The simplest among them produce digital blood pressure readings, not much different to use than reading a digital watch versus reading a traditional clock or a mercurial thermometer.

Omron IntelliSense HEM907, which features a digital display, is a good example, removing the need for a stethoscope and helping to avoid inaccurate readings. 

It’s a plug-and-play, portable design, packed with features like storage, body movement detection, and an irregular heartbeat detector. Use is as easy as putting it on, turning it on, and reading the results. I’ll come back to that part in a second.

The Reister Big Ben floor model, also known as an aneroid monitor, is closer to what most folks think of when it comes to sphygmomanometers. Units like the Big Ben feature a clock-face style display, but with one hand instead of two,

Reading a manual scale versus a digital one takes a little more practice to get an accurate reading, but for tracking trends, an exact reading isn’t super necessary. The Reister sphygmomanometers feature auto-balancing making accurate readings easier.

Between the two extreme examples mentioned so far, there are steps in between. Neither is better or worse. A good indicator of which will work better for you is to consider your favourite wristwatch or wall clock.

If you don’t mind changing batteries, then go digital. If antiquity is your style, check out the dial-based sphygmomanometers.

 

Author: Steven John Cumper, B.App.SC. (Osteo.), M.Ost., is a businessman with a strong foundation in biomedical science and osteopathic medicine, who founded and led Medshop to international success, culminating in its acquisition by the Bunzl Group in September 2021, where he continues to serve as Managing Director (Medshop Group).