A blood pressure cuff is a device consisting of an inflatable rubber bladder, a handheld air pump, and a pressure meter with a valve attached to it. As the name suggests, it’s used to take one’s blood pressure readings.
The inflatable rubber bladder is fastened around the person’s arm, and the pressure meter indicates the pressure of the cuff. The handheld air pump is used to inflate the cuff. Once inflated, its air valve is slowly opened to release air pressure. As the air is released and pressure goes down, the person taking blood pressure closely listens to arterial blood flow sounds through a stethoscope.
The heartbeats cause blood to push through arteries, which causes fluctuations in arterial pressure. These fluctuations result in particular ‘highest’ and ‘lowest’ amounts of pressure, known as systolic and diastolic pressure respectively.
The Procedure of Taking Blood Pressure
A stethoscope is positioned under the inflated cuff while taking blood pressure to listen to the turbulence of blood flow. Initially, it’s inflated sufficiently above the expected highest (systolic) pressure, at which point, no sounds can be heard via the stethoscope as the blood flow is stopped. As the valve is slowly opened, the pressure gradually diminishes until it reaches the arterial systolic pressure, where the blood starts to flow past the cuff, which can be heard via the stethoscope. The doctor or nurse makes a note of the cuff’s pressure value at that point, giving them the systolic pressure reading.
As the cuff empties more of its air, the sounds of blood flow turbulence can be heard continuously, until the cuff’s air pressure falls under the patient’s diastolic pressure, and the sounds stop. At that point, the nurse takes another reading from the pressure meter, indicating the patient’s diastolic pressure.
Guidelines for Proper Usage
- It’s important to select the correct cuff size. For this, measure the patient’s limb and choose an appropriate cuff size according to the sizes mentioned on the cuff’s box or manual, or on the cuff itself. The accuracy of readings can largely depend on the appropriateness of the cuff size you work with.
- Make sure the cuff, hose, and tube are undamaged and clean before using. If you find a cuff to be tearing or old, replace it. Don’t inflate it when it’s not applied to a patient’s limb.
- Inspect the patient’s limb carefully before applying it to select an appropriate measurement site.
- To apply, wrap it around the patient’s upper arm and ensure that its index line is positioned between the cuff’s range marks. If it doesn’t turn out that way, use a different size of cuff.
- Make sure you align the arrow market artery over the person’s brachial artery. Follow up by pressing the soft and rough closure sides together.
- The blood pressure cuff should ideally be a snug fit, but not very tight—with sufficient space to fit a finger or two between the cuff and the patient.
If you’d like to know more about using blood pressure cuffs properly, here’s an in-depth blood pressure cuff guide to help you out.
There are various types of blood pressure cuffs available in the market, including aneroid, mercury, and digital ones. Digital cuffs are automatic, while aneroid and mercury variants support manual use, requiring a stethoscope.
You can take a patient’s blood pressure while their seated, standing, or laying down. In the seated position, their arm should be at the same level as the heart, ideally being supported and slightly flexed. Make sure the patient is calm while you take their blood pressure, which means if they’re anxious, give them a few minutes to relax to ensure accuracy.