Factors That Affect Your Blood Pressure Reading

Factors That Affect Your Blood Pressure Reading

Have you ever taken your blood pressure and thought, “Hmmm… that’s not quite right”?

While it is normal for our blood pressure to fluctuate throughout the day or in response to a stressful event, it is also crucial to consider inaccuracies in your blood pressure readings when they seem a little off. In this article, we will be discussing the reasons behind inaccurate blood pressure readings and explore some helpful tips for maximizing the accuracy of at-home blood pressure readings.

What is a Blood Pressure Reading?

Factors That Affect Your Blood Pressure Reading

Blood pressure is a measurement of the amount of force exerted on your circulatory system. Arteries, veins, and capillaries are all circulatory vessels designed to transport blood around the body. Maintaining safe pressure in these vessels prevents damage and the risk of developing heart disease. Having high blood pressure can be dangerous to your overall health.

Blood pressure is represented by two numbers measured in millimeters of mercury (mmHg). Each of these numbers refers to a different measurement. Systolic blood pressure (the top number) represents the amount of force exerted against your blood vessels during a heartbeat. This is the highest amount of pressure your vessels will be exposed to, so having a high systolic pressure puts you at increased risk for vessel damage. Diastolic blood pressure (the bottom number) indicates how much force is being exerted on the vessels between heartbeats. Having high diastolic pressure is often accompanied by having high systolic pressure.

What is Considered Normal for a Blood Pressure Reading?

The CDC outlines normal blood pressure levels to be 120 mmHg or less for systolic pressure and 80 mmHg or less for diastolic pressure (120/80). It is normal and healthy for your blood pressure to be higher or lower than these values throughout the day. Exercise, stress, nervousness, and excitement increase our blood pressure. Having a higher-than-expected blood pressure reading for a short period is normal and is not a cause for concern. 

What is Hypertension?

Chronically high blood pressure (even when at rest) is a medical concern that can lead to heart disease and other medical conditions. Hypertension is the medical term for high blood pressure. There are different stages of diagnosis for high blood pressure and hypertension:

  • Elevated Blood Pressure – 120-129 mmHg / 80 or less mmHg
  • Stage 1 Hypertension 130-139 mmHg / 80-90 mmHg
  • Stage 2 Hypertension – 140 or higher mmHg / 90 or higher mmHg

Prolonged exposure to high blood pressure is damaging to the blood vessel and heart. People with chronic hypertension are at risk for developing heart disease or experiencing a medical emergency like a stroke or heart attack.

How Common is Hypertension?

According to Statistics Canada, hypertension affects almost 1 in 4 Canadian adults, and the lifetime incidence of developing high blood pressure is estimated to be 90%.

Health Factors That Cause High Blood Pressure

Many factors contribute to high blood pressure. Because our circulatory system is connected to every organ in our body, many different disorders and substances can negatively impact blood pressure. Some common medical conditions associated with hypertension include:

  • Obesity and Elevated BMI – Obesity and elevated total body fat values result in additional strain on the body. Chronic stress and damage to the internal organs (including the heart and blood vessels) contribute to hypertension. Additionally, people with elevated body mass indexes (BMI) are more likely to be consuming a diet high in processed foods, saturated fats, and salt. Poor diet is associated with heart disease and hypertension.
  • Medications – Some medications used to treat other conditions can have a side effect of elevated blood pressure. Some antidepressants, pain medications, and birth control pills contribute to high blood pressure. On the other side of the coin, many people with hypertension are not adequately treated with medications meant to control their blood pressure or do not stick to their prescribed treatment plan. 
  • Pre-Existing Medical Conditions – Many health conditions impact blood pressure. All heart-based medical conditions like heart arrhythmias, heart disease, and heart failure have a massive impact on blood pressure values. Other chronic health conditions that cause hypertension include diabetes, chronic obstructive pulmonary disease (COPD), anxiety, kidney disease, and substance abuse disorders.
  • White Coat Syndrome – If you get nervous when you go to the doctor’s office, you are not alone! White Coat Syndrome is the name for anxiety and nervousness about seeing a doctor that elevates blood pressure for a short period.
  • Caffeine – Caffeine is a stimulant drug that increases energy and alertness. In large doses or people with low tolerances, caffeine can cause a sharp spike in blood pressure and anxiety. Caffeine-induced high blood pressure is short-lived, and your blood pressure will return to normal once the caffeine has been filtered out of your system.

Proper management of underlying medical conditions and substances is essential for treating hypertension. Left uncontrolled, the damage to the circulatory system can become so extreme that a cardiac medical emergency occurs. But how do I measure my blood pressure, and how can I make sure it is as accurate as possible?

How Is Blood Pressure Measured?

Blood pressure is measured using a sphygmomanometer (try saying that ten times fast!) A manual sphygmomanometer is made of two distinct parts: the inflatable cuff that goes around the arm and a pressure meter to read the air pressure in the cuff. 

A stethoscope is used to listen to the heart sounds throughout the measurement. Inflation of the cuff blocks all blood flow through the artery in the arm. Once the cuff begins to deflate, a heartbeat will be detectable as blood re-enters the artery. The value on the pressure meter when the first heartbeat is heard is considered systolic pressure. As the cuff continues to deflate, the heartbeat sounds will continue. The pressure value on the meter when the heartbeat sounds disappear is considered the diastolic pressure. 

Blood pressure monitoring can be tricky, especially if you are new to regular monitoring. Here are a couple of tips to get the most accurate results when checking your blood pressure at home!

Proper Technique For At-Home Blood Pressure Monitoring

Taking your blood pressure regularly at home is a great way to check for hypertension and treatment efficacy. That said, at-home monitoring offers many challenges for ensuring accurate, consistent readings. Here are some tips to increase the accuracy of at-home monitoring:

  • Check Your Machine or Manual Cuff – Proper maintenance of the automatic device or manual cuff is crucial for accurate readings. Check to make sure there are no visible signs of damage or tears in the cuff before using.
  • Use The Correct Size of Cuff – “Cuff hypertension” is a phenomenon that occurs when a person uses a blood pressure cuff that is too small for their arm. If the cuff barely fits around your arm, the blood pressure reading will be artificially higher than it actually is. Use a larger cuff to get a more accurate reading.
  • Check Your Posture – Blood pressure readings can significantly change depending on the position. Unless your doctor specifically instructs you to get into a particular position, sit comfortably in a quiet area to take your blood pressure.
  • Ensure Good Arm Position – Ideal positioning for your arm during a blood pressure reading is straight out at the height of your heart. Variations in this can cause inaccuracies.
  • Support Your Arm – An unsupported arm can dramatically impact the reading of diastolic blood pressure. Ensure that your arm is adequately supported on a chair or hold it at the elbow throughout the measurement to get an accurate reading.
  • Double Check With the Other Arm – Blood pressure readings can be different from arm to arm, off by as much as 10 mmHg! If you are unsure if your blood pressure reading was accurate, take it on both arms to double-check.

All of these tips apply to both manual and automatic blood pressure reading methods. But what are the benefits and drawbacks of each at-home monitoring method?

Manual At-Home Blood Pressure Monitoring

Manual At-Home Blood Pressure Monitoring

While automatic blood pressure devices are becoming more popular, some people still choose to check their blood pressure at home using the manual method. 

Manual blood pressure readings are the traditional method but require advanced technique and training for the best results. Manual blood pressure is also hard to perform on yourself.

Because manual blood pressure readings rely on human interpretation of heartbeat sounds throughout the measurement, the accuracy can significantly vary depending on the user. Manual blood pressure readings have higher values on average than automatic devices.

If you choose to use the manual method for your at-home blood pressure readings, ensure that the user is experienced and well-trained.

Automatic At-Home Blood Pressure Monitoring

Automatic At-Home Blood Pressure Monitoring

The more popular option for at-home blood pressure reading is automatic devices. Now, widely available automatic blood pressure devices can be incredibly accurate and much more user-friendly than manual monitors. Automatic monitors are easier to use without assistance and display the reading for easy recording and understanding.

You will find automatic blood pressure readers in places other than home. Many grocery stores, pharmacies, and drug stores have blood pressure reading machines available for people to use. The InBody BPBIO 750 is an incredibly accurate blood pressure monitor featured in many medical offices, pharmacies, gyms, and other facilities across the country. This automatic kiosk-style monitor is an excellent option for regular checks to ensure that your at-home monitor delivers accurate readings.

Putting It All Together

Overall, monitoring blood pressure is a vital health screening to perform regularly. High blood pressure damages blood vessels and can cause serious medical conditions.

Knowing what blood pressure values are considered hypertensive helps to identify underlying health problems and get early treatment. If you have been diagnosed with a new medical condition, ask your doctor if regular blood pressure monitoring would benefit your health.

Manual and automatic blood pressure reading devices can both produce accurate blood pressure readings. The manual method requires more experience and training to get accurate readings and is less accessible in the home setting. Automatic blood pressure readers are user-friendly and easily accessible for at-home monitoring. 

Whichever method you select for measuring your blood pressure, there is always a risk of an inaccurate reading. Following some simple tips about positioning, device maintenance, and cuff size can significantly reduce the number of false readings.


Claire is a registered nurse based in Alberta, Canada. She is a certified operating room nurse and enjoys creating educational content for her patients.

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