Equipment factors
1. Blood pressure monitor quality: There are many brands and models of blood pressure monitors, and the quality varies. Products that have been professionally certified, such as those that meet relevant international standards (such as AAMI, ESH, BHS, etc.), are usually more accurate. Some inferior or counterfeit products may have defects in sensor accuracy, inflation and deflation systems, etc., which will lead to inaccurate measurement results.
2. Equipment calibration: Electronic blood pressure monitors need to be calibrated regularly to ensure accuracy. It is generally recommended to send the blood pressure monitor to a professional institution for calibration every year. If it is not calibrated for a long time, or the blood pressure monitor is affected by external forces such as collisions and falls, the internal components may be displaced or damaged, affecting the measurement accuracy.
3. Cuff problems: The size, material and state of the cuff have an important impact on the measurement results. If the cuff is too wide or too narrow, the measurement value will be deviated. Generally speaking, the width of the cuff airbag should cover about 2/3 of the circumference of the upper arm. In addition, if the cuff material is not elastic, aged or damaged, it may also cause uneven inflation and affect the measurement accuracy.
Environmental factors
1. Temperature: If the ambient temperature is too low or too high, it may cause the human blood vessels to contract or expand, thus affecting the blood pressure measurement results. Generally speaking, it is more appropriate to measure at an ambient temperature of 18℃-25℃.
2. Noise: A noisy environment will make the subject irritable and distracted, leading to sympathetic nerve excitement, which will increase blood pressure and affect the accuracy of the measurement. When measuring, you should try to choose a quiet environment, and the noise level should be lower than 40 decibels.
3. Electromagnetic interference: If the electronic blood pressure monitor is close to a strong electromagnetic field source, such as a microwave oven, TV, mobile phone, etc., it may be affected by electromagnetic interference, affecting the normal operation of its electronic components and causing errors in the measurement results.
Operational factors
1. Cuff wearing: The position and tightness of the cuff have a great influence on the measurement results. The cuff should be wrapped flatly on the upper arm, with the lower edge 2-3 cm away from the elbow fossa and kept at the same level as the heart. If the cuff is wrapped too loosely, the measurement value will be too high; if it is wrapped too tightly, the measurement value will be too low.
2. Measurement posture: The correct measurement posture is to sit or lie down with your arms naturally relaxed, keeping your upper arms at the same level as your heart. If the arm position is too high, the measured value will be low; if the arm position is too low, the measured value will be high.
3. Number of measurements and intervals: When taking multiple measurements in a row, if the interval is too short, the blood vessels have not returned to normal after the last measurement, which will lead to inaccurate measurement results. It is generally recommended to take 1-2 minutes between each measurement, and take the average of multiple measurements as the measurement result.
Subject factors
1. Physiological state: If the subject has engaged in strenuous exercise, emotional excitement, drinking, smoking or drinking coffee before the measurement, the blood pressure will rise in a short time, resulting in inaccurate measurement results. In addition, the subject's age, gender, body posture changes, etc. will also affect blood pressure.
2. Body posture: If the subject's body posture is unstable during measurement, such as bending over, hunching over, crossing legs, etc., it may affect blood circulation and cause deviations in blood pressure measurement values.
3. Arm condition: If the subject's upper arm has edema, scars, vascular malformations, etc., it will affect the sphygmomanometer's accurate measurement of brachial artery blood pressure.
