From the Guidelines
The proper technique for measuring blood pressure involves having the patient sit quietly for 5 minutes with their back supported and feet flat on the floor, as recommended by the most recent guideline from 2021 1.
Key Steps for Accurate Blood Pressure Measurement
- Step 1: Prepare the patient by having them relax in a chair with their back supported and feet on the floor for more than 5 minutes, avoiding caffeine, exercise, and smoking for at least 30 minutes before measurement, and ensuring their bladder is empty 1.
- Step 2: Use proper technique for BP measurements by supporting the patient's arm, positioning the cuff at the level of the right atrium, using the correct cuff size (bladder encircling 80% of the arm), and using a validated and calibrated BP measurement device 1.
- Step 3: Take the proper measurements by recording BP in both arms at the first visit, using the arm with the higher reading for subsequent measurements, separating repeated measurements by 1-2 minutes, and using a palpated estimate of radial pulse obliteration pressure to estimate systolic blood pressure (SBP) 1.
- Step 4: Document accurate BP readings by recording SBP and diastolic blood pressure (DBP) as the onset of the first Korotkoff sound and disappearance of all Korotkoff sounds, respectively, and noting the time of the most recent BP medication taken before measurements 1.
- Step 5: Average the readings by using an average of at least two readings obtained on at least two occasions to estimate the individual's level of BP 1.
- Step 6: Provide BP readings to the patient by providing the SBP and DBP readings both verbally and in writing 1.
From the Research
Proper Technique for Measuring Blood Pressure
To measure blood pressure properly, several factors must be considered, including the method of measurement, the location of measurement, and the position of the arm. The following are key points to consider:
- Method of Measurement: There are several methods for measuring blood pressure, including the auscultatory method using a mercury sphygmomanometer, the oscillometric technique used in electronic devices, ultrasound, and the finger cuff method 2.
- Location of Measurement: The preferred location for measuring blood pressure is the upper arm, but measurements can also be taken at the wrist or finger 2, 3.
- Position of the Arm: The position of the arm can affect blood pressure measurements, with significant differences in readings obtained when the arm is placed at the level of the right atrium versus when it is placed on a bed or desk 4.
- Cuff Size: Using a cuff that is too small or too large can lead to errors in blood pressure measurement 2.
- Deflation Rate: The rate of deflation of the cuff can also affect blood pressure measurements, with too rapid deflation leading to errors 2.
Factors to Consider
When measuring blood pressure, several factors can influence the accuracy of the readings, including:
- White Coat Effect: Clinic readings may be higher than average daytime blood pressure due to the white coat effect, which is the difference between clinic readings and average daytime blood pressure 2.
- Patient Position: The position of the patient, whether sitting or supine, can affect blood pressure readings, with supine positions often resulting in higher readings 4.
- Arm Position: The position of the arm, whether at the level of the right atrium or on a bed or desk, can also affect blood pressure readings 4.
Recommendations
Based on the available evidence, the following recommendations can be made:
- Use a Validated Device: Use a validated electronic device that employs the oscillometric technique to measure blood pressure 5.
- Measure at the Upper Arm: Measure blood pressure at the upper arm, as this is the preferred location 2.
- Position the Arm Correctly: Position the arm at the level of the right atrium to ensure accurate blood pressure readings 4.
- Use the Correct Cuff Size: Use a cuff that is the correct size for the patient's arm to ensure accurate blood pressure readings 2.