The role of ambulatory blood pressure monitoring is mainly fourfold: first, to diagnose hypertension, second, to improve the accuracy of hypertension diagnosis, third, to assess the risk of cardiovascular and cerebrovascular diseases and improve the level of risk assessment, and fourth, to assess the effect of antihypertensive treatment.
In addition, it can also guide the individualized treatment of hypertension, improve the quality of antihypertensive treatment, achieve 24-hour blood pressure control, and give full play to the role of antihypertensive treatment and prevention of cardiovascular and cerebrovascular complications.
Although we understand the necessity of ambulatory blood pressure monitoring, but what is ambulatory blood pressure monitoring, how do we measure it ourselves and other new doubts, the next answer one by one.
1.What is ambulatory blood pressure monitoring, and how should we operate?
(1) What is ambulatory blood pressure monitoring?
Ambulatory blood pressure monitoring is a technique that monitors blood pressure continuously for 24 hours without affecting the patient’s daily activities, and can obtain multiple blood pressure values within 24 hours, which can actually reflect the pattern of blood pressure changes throughout the day.
In simple terms, it means that the subject wears a ambulatory blood pressure recorder that does not interfere with the free activities of daily life, and the device will automatically take blood pressure measurements at set intervals.
(2) How should ambulatory blood pressure monitoring be performed?
Before ambulatory blood pressure monitoring, it is best to measure bilateral upper arm office blood pressure, or to find out the results of previous bilateral upper arm blood pressure measurements.
If the difference in blood pressure between the two upper arms is ≥10 mmHg, the upper arm with the higher blood pressure should be selected for ambulatory blood pressure monitoring; if the difference in blood pressure between the two upper arms is <10 mmHg, it is recommended that the non-dominant arm be selected for monitoring to reduce the effect of arm activity on blood pressure monitoring.
Also during automatic ambulatory blood pressure measurement, care needs to be taken to keep the arm on the measurement side stationary.
After wearing the sphygmomanometer, two manual measurements with the ambulatory blood pressure monitor are taken first to test whether the sphygmomanometer is working properly. After monitoring, it is best to take two manual measurements with the ambulatory blood pressure monitor again before removing the monitor to confirm that the monitor is working properly.
2.Specific ambulatory blood pressure monitoring program and standardized report of ambulatory blood pressure monitoring
(1) What is the specific ambulatory blood pressure monitoring program?
The ambulatory blood pressure monitoring program consists of the following items, which can be operated according to the overall program to ensure the accuracy of monitoring.
– The first is the selection of the ambulatory blood pressure monitor. The recommended model of ambulatory blood pressure monitor with proven accuracy is recommended; the appropriate size cuff is selected according to the arm circumference.
– The second is the automatic measurement setting of the ambulatory blood pressure monitor, which should ensure that the monitoring time is not less than 24h as far as possible; measurements are taken every 15-30 minutes during the day and every 30 minutes at night.
– Then is the ambulatory blood pressure diary card, need to record waking up, sleep, nap time, etc.; to provide monitoring the day of medication information, to help later write ambulatory blood pressure assessment report.
– Finally, there is effective ambulatory blood pressure monitoring, with valid readings at 70% or more of the readings set to be obtained; at least 20 valid readings during the day and at least 7 valid readings at night.
(2) What are the contents of the standardized report of ambulatory blood pressure monitoring?
The content of the 24-hour ambulatory blood pressure monitoring report should be standardized, and the content of the ambulatory blood pressure report generated by different devices should be homogenized. A standardized report of ambulatory blood pressure monitoring is only qualified if it includes the following elements
A 24-hour graph of blood pressure fluctuations over time, with daytime and nighttime periods marked according to the patient’s rest time on the day of monitoring, as well as raw blood pressure and heart rate data.
It is also necessary to calculate the average systolic blood pressure, diastolic blood pressure and heart rate for each time period, as well as the number of measurements and the efficiency rate; to calculate the rate of decrease of systolic blood pressure/diastolic blood pressure at night; to calculate the standard deviation, coefficient of variation, maximum and minimum values of systolic blood pressure, diastolic blood pressure and heart rate for each time period.
3.Indications for ambulatory blood pressure monitoring and monitoring of special populations
(1) What are the indications for ambulatory blood pressure monitoring?
At present, several domestic and international guidelines recommend the use of 24h ambulatory blood pressure monitoring to diagnose hypertension. This is because ambulatory blood pressure monitoring can assess the dynamic changes in blood pressure over 24 hours and detect excessive fluctuations in blood pressure such as paroxysmal increases in blood pressure.
It can also effectively identify blood pressure abnormalities in out-of-office hours, especially pathological states such as nocturnal blood pressure not falling and nocturnal hypertension, and these blood pressure characteristics are suggestive for clinical screening of secondary hypertension.
Therefore, patients with in-office blood pressure at high normal values or those who have developed significant target organ damage need to be alerted to the possibility of combined risk factors for occult hypertension and should be screened with 24-h ambulatory blood pressure monitoring to avoid missed diagnoses.
Ambulatory blood pressure monitoring is also recommended for newly identified patients with grade 1-2 office hypertension to exclude white coat hypertension and to clarify the diagnosis of hypertension.
(2) What are the contraindications to ambulatory blood pressure monitoring?
As a noninvasive blood pressure measurement method, ambulatory blood pressure monitoring has no absolute contraindications, but its results need to be evaluated with caution in some populations.
For example, in patients with atrial fibrillation, a single blood pressure measurement is prone to error due to absolute arrhythmia, and multiple measurements can improve the accuracy of blood pressure assessment.
In patients with persistent atrial fibrillation with an unstable ventricular rate, the ambulatory sphygmomanometer may produce a systolic blood pressure similar to that measured by auscultation, but the diastolic blood pressure may be slightly higher than that measured by auscultation.
In addition, for patients with insomnia and nocturnal polyuria, the effect of these factors on nighttime blood pressure should be considered; and for patients with asymmetrical blood pressure in both arms, the higher side should be confirmed for monitoring.
(3) What is the role of ambulatory blood pressure monitoring in special populations?
The white coat effect is common in patients with suspected refractory hypertension, so the results of ambulatory blood pressure monitoring can be used to distinguish between true and pseudo-refractory hypertension.
Patients with hypertension combined with obesity, metabolic syndrome, diabetes, renal disease, and obstructive sleep apnea hypoventilation syndrome are often characterized by an increased risk of developing covert hypertension, abnormal circadian rhythms in blood pressure, and large fluctuations in blood pressure, and therefore require ambulatory blood pressure monitoring to accurately assess blood pressure.
Ambulatory blood pressure in childhood can more accurately predict the onset of hypertension and help detect occult hypertension and secondary hypertension, so ambulatory blood pressure monitoring is recommended to clarify the diagnosis of hypertension in children.
24-hour ambulatory blood pressure, especially in mid-pregnancy when insufficient nocturnal blood pressure drop occurs, can help identify hypertension in pregnancy and predict the risk of preeclampsia.
The possibility of occult hypertension should be alerted in those with combined hypertensive target organ damage such as left ventricular hypertrophy in early pregnancy, but no significant elevation in office blood pressure.
24-hour ambulatory blood pressure monitoring is recommended for pregnant women with suspected white coat hypertension, covert hypertension, and wide fluctuations in blood pressure during pregnancy.
References
[1] Committee on Ambulatory Blood Pressure Monitoring Guidelines of the Chinese Hypertension Consortium.2020 Guidelines for Ambulatory Blood Pressure Monitoring in China [J]. Chinese Journal of Circulation,2021,36(04):313-328.
[2]Li Yanping. Study on ambulatory blood pressure monitoring during treatment of hypertension in the elderly[J]. Chinese and Foreign Women’s Health Research,2021(19):89-90.