How To Take Blood Pressure Manually

Understanding blood pressure

While automatic blood pressure monitors are widely used both in medical settings and in patient’s homes, manual measurement may be necessary in critical care units or emergency departments (EDs) and when an automatic monitor is either not available or not working properly. 

This guide will walk you through the process of how to take blood pressure manually, providing essential tips and addressing common challenges. 

What is blood pressure and how is it measured? 

Before diving into the step-by-step process, it’s important to understand what blood pressure is and why it is measured. The amount of pressure (or force) of blood on the walls of the arteries as it travels through them is known as blood pressure.  

It is recorded as two numbers: 

• Systolic blood pressure (SBP): This is the top number. It denotes the pressure (or force) in the arteries when the heart beats.
• Diastolic blood pressure (DBP): This is the bottom number. This is the pressure in the arteries when the heart is at rest between beats. 

Regular blood pressure for an adult is less than 120/80. Several factors, such as age, medications, activity level, and overall health status can affect blood pressure. 

Equipment needed to take blood pressure manually 

To manually measure blood pressure, you will need the following equipment: 

Stethoscope: This is used to listen to the Korotkoff sounds, which are the pulse sounds of blood flow heard as the cuff pressure is released. 

Sphygmomanometer: This is the piece of equipment that is applied to the patient. Parts included are: 

• An inflatable cuff and bladder (which is wrapped around the patient’s arm)
• A bulb (the part you squeeze) to inflate the cuff
• A valve (which is on the bulb and goes in two positions, closed and opened). The valve is what you twist to release and deflate the cuff so you can hear the Korotkoff sounds
• Pressure gauge 
• Two tubes: One tube attaches to the pressure gauge to the cuff and bladder. The second tube attaches the bulb and air release valve to the cuff and bladder. 

Steps to take blood pressure manually 

The more you practice how to take blood pressure manually, the better at it, you will become. The steps on how to do this are as follows: 

Step 1: Prepare the patient 

• Ensure your patient is relaxed. If ambulatory, ask your patient to go to the bathroom to empty their bladder. Next, your patient should be seated for at least five minutes before you measure their blood pressure. Once seated, ensure they’re sitting comfortably with their back supported, their feet flat on the floor, and their ankles and legs uncrossed. 
• Position the arm correctly. The patient’s arm should be supported on a flat surface at the same level as their heart with their palm facing up. The patient’s arm should be free of clothing to avoid obscuring the Korotkoff sounds. 
• Avoid recent activities that are known to raise blood pressure. Confirm your patient has not smoked, consumed caffeine, or engaged in any physical activity at least 30 minutes prior to taking their blood pressure, as these can temporarily elevate it. Ask your patient not to talk during the measurement. 

Step 2: Apply the cuff — size and placement matter 

• Choose the appropriately sized cuff. Using a cuff that is too small or large can lead to inaccurate readings. Using a cuff that is too small can result in a falsely higher blood pressure reading. Conversely, using a cuff that is too large can result in a falsely lower reading. 
• Consider the cuff length and width. The cuff should cover approximately 75% to 100% of the total circumference around the upper arm. The width of the cuff should be at a height (wide enough) to cover at least 40% to 80% of the length from the shoulder to the elbow. 
• Place the cuff on the arm correctly. First, palpate the brachial artery. Place the lower edge of the cuff on the upper arm, approximately one inch (2.5 cm) above the bend of the elbow. The artery marker on the cuff should align with the brachial artery, which is located slightly medial on the inner aspect of the arm. The cuff should fit firmly but not too tight. Make sure you can fit one finger under the cuff to ensure it’s not too tight or too loose. 

Step 3: Estimate the systolic pressure 

• Palpate the brachial pulse. Before using the stethoscope to auscultate and obtain your patient’s blood pressure, palpate their brachial pulse.
• Inflate the cuff. While palpating the brachial pulse, inflate the blood pressure cuff until you can no longer feel it. Look at the gauge to see the pressure reading when their palpable pulse disappears. This number is their estimated systolic pressure.
• Deflate the cuff. Slowly release the pressure and allow their arm to rest for one minute before proceeding. 

Step 4: Measure the blood pressure 

• Ensure good placement of the stethoscope. Position your stethoscope’s diaphragm over the brachial artery, just below the cuff’s edge.
• Inflate the cuff. Quickly inflate the cuff to 20 to 30 mmHg above the estimated systolic pressure you just obtained.
• Slowly deflate the cuff. Release the air at a rate of 2 to 3 mmHg per second while listening through your stethoscope. 

Step 5: Identify the Korotkoff sounds 

Knowing how to take blood pressure manually requires you to know what Korotkoff sounds are.  Korotkoff sounds are the circulatory pulse sounds you hear when auscultating an artery with a stethoscope when taking a BP manually.  

• First Korotkoff sound (systolic pressure): As the pressure in the cuff is released, listen for the first pulse sound, known as the first Korotkoff sound. The reading at the time of hearing the first Korotkoff sound is known as the systolic pressure.
• Disappearance of the Korotkoff sound (diastolic pressure): Continue to slowly release the pressure at a rate of 2 to 3 mmHg per second, as you continue to listen with your stethoscope. The point at which the sound stops indicates the level of the diastolic blood pressure. 

Step 6: Record the reading 

Document the blood pressure reading as systolic over diastolic (example: 120/80). State in your documentation which arm was used, the patient’s position (sitting, lying, or standing), and any additional relevant factors that may have influenced the reading. Two examples: The patient continued to speak throughout the measurement, or the patient was anxious and hyperventilating. 

Common challenges in manual blood pressure measurement 

Even with the best technique and knowing how to take blood pressure manually, several factors can lead to inaccurate readings. Understanding and addressing these challenges is important so you can obtain accurate measurements: 

1. Auscultatory gap 

An auscultatory gap is the period during which Korotkoff sounds disappear before reappearing, which can lead to possible underestimation of the systolic pressure or overestimation of the diastolic pressure. To avoid this, try to obtain an estimated SPB prior to auscultation.  

2. Patient-related factors 

• Movement: Any movement by the patient, such as talking or shifting position, can interfere with the measurement.
• Anxiety (sometimes called white coat syndrome): Anxiety can cause temporary spikes in blood pressure. Ensure your patient is as calm as possible, ask them to take a few deep breaths first, and consider taking more than one reading or measuring their blood pressure at a different time during the visit if anxiety is suspected. 

3. Improper cuff size or placement 

A cuff that is too tight or loose can significantly skew blood pressure readings. Be sure to use the correct cuff size and position it correctly. 

4. Observer error 

Manual blood pressure measurement requires a trained ear and keen observational skills. Inaccurate readings can occur if a nurse or other healthcare professional is inexperienced or distracted.  

Tips for improving manual blood pressure measurement skills 

• Practice regularly. Regular practice will help you become more proficient at identifying Korotkoff sounds and recognizing potential errors.
• Use both arms initially. For initial measurements, take blood pressure readings in both arms and use the arm with the higher reading for later measurements.
• Educate patients. Encourage patients to regularly check their blood pressure at home, especially if they have or are at risk for hypertension. Educate them on how to accurately measure their blood pressure as part of their self-care routine.
• Avoid taking blood pressure in an arm affected by certain health conditions. This includes  a dialysis shunt, lymphedema, arterial or venous lines, recent surgery, wounds, mastectomy side, paralysis or paresis. 

Importance of accuracy in manual blood pressure measurement 

Accurate blood pressure measurement is a necessary component in diagnosing and managing hypertension (HTN) which a leading risk factor for cardiovascular disease. When blood pressure readings are incorrect, it can lead to underdiagnosed or over-diagnosed HTN which can result in undertreatment or over treatment. Using the proper techniques on how to take blood pressure manually can lead to improved health outcomes for your patients.