24-hour Blood Pressure Monitoring

Blood pressure can be monitored in many different settings including a clinic, hospital or at home. 

Blood pressure is the pressure of your blood on the walls of your arteries as your heart pumps it around your body. Your blood pressure will go up and down naturally throughout the day depending on what you are doing. For example, it will go up if you are doing exercise and down when you are resting. 

How is the test done? 

A sleeve, or cuff, is placed firmly over your upper arm. The cuff often has markers to line up with the inside bend of your arm. When the measurement is happening, the unit will pump air into the cuff and slowly inflate, getting tighter around your arm. You may feel some numbness or tingling as the cuff gets tighter. The cuff will then slowly deflate, and the tightness will reduce. 

A blood pressure reading with two numbers will be recorded to measure when the blood flow to your arm stopped and when it returned. These numbers reflect the pressure of blood inside the walls of your artery. 

For a 24-hour or ambulatory blood pressure monitor, you will need to wear a blood pressure unit. The unit consists of a blood pressure cuff that is worn on your upper arm and connected to a monitor. You wear the monitor on a strap over your shoulder.  

For the next 24 hours, your heart rate and blood pressure will be measured at 20-30 minute intervals during the day and night. When you feel the cuff getting tighter, it’s important to stop and rest until the measurement is complete. Usually each reading takes 30-40 seconds. 

When you have the 24-hour blood pressure system connected, it will take about 15 minutes to have the cuff put on and get instructions. You will need to return to the hospital at the same time the next day (24 hours later) to have the strap and monitor taken off. 

If you are monitoring your blood pressure yourself at home, view our factsheet on how to prepare and how to perform the reading correctly. 

Download the fact sheet: Measuring your blood pressure at home (PDF)

What does the test show? 

Blood pressure monitoring will measure the force at which blood travels around your body. Everyone has a blood pressure and your doctor will tell you what your ideal blood pressure should be, based on your medical history. 

Visit our blood pressure and your heart page to learn more. 

Why is the test done? 

High blood pressure is a very important risk factor for heart disease. Measuring your blood pressure at home is a good way to understand how your blood pressure changes during the day, or from one day to the next, in response to lifestyle changes and medical treatment. Your doctor may use your home measurements to make treatment decisions.  

Preparing for the test 

There’s nothing special you need to do before having your 24-hour blood pressure monitor fitted.

However, while you are wearing the unit you must: 

• Wear a loose-fitting shirt 
• Remain still during the readings (when the cuff tightens)  
• Record the time, any symptoms, and your mood, activity, and bedtime in your patient diary  
• Press the button on the monitor as soon as you notice symptoms such as dizziness, headaches, chest pain or sudden shortness of breath 
• Make sure the monitor stays connected while you undress 
• Take your normal medications. 

 You must also follow these important guidelines: 

• Don’t wear long-sleeved sweaters or dresses  
• Don’t take the cuff off or remove the batteries from the unit  
• Don’t get the monitor wet (i.e., don’t swim, shower or bathe)  
• Don’t use power tools or heavy equipment, as vibrations can disrupt the monitor. 

Knowing what your blood pressure is and having it regularly checked is important in maintaining a healthy heart.