Blood pressure has long been measured with a sphygmomanometer, a method known as incidental blood pressure measurement. Occasional blood pressure measurements play an important role in identifying hypertensive patients, guiding the treatment of hypertension, evaluating the prognosis of patients, and providing preventive care. However, there are some shortcomings of incidental blood pressure measurement, for example, some patients have their blood pressure controlled in the normal range in the physician’s office while the patient still has target organ damage and cardiovascular disease; some patients have high blood pressure in the physician’s office but the patient does not have cardio-cerebral or renal damage, which makes many hypertensive patients feel confused. In addition, the shortcomings of incidental blood pressure measurement include: (1) some patients with mild hypertension are easily delayed in diagnosis because their blood pressure is only elevated at certain times; (2) the main points of distinction between primary and secondary hypertension cannot be made from the blood pressure values; and (3) medication cannot be used rationally according to the peak time of blood pressure fluctuations. Zhang Yu, Department of Nephrology, Xiyuan Hospital, Chinese Academy of Traditional Chinese Medicine
Because the severity of hypertension and its target organ damage cannot be evaluated more accurately, target organ damage or cardiovascular disease cannot be prevented or mitigated more effectively.
In order to solve the above problems, medical experts have adopted the method of 24-hour ambulatory blood pressure monitoring for hypertensive patients to grasp the pattern of blood pressure changes. Years of medical practice have proven that the application of 24-hour blood pressure monitoring can overcome the above-mentioned problems of the current occasional blood pressure measurement. It is of practical significance for hypertensive patients and their family members to master the basic knowledge about 24-hour blood pressure monitoring and its clinical significance to further understand their diagnosis, treatment and preventive health care work, so the scientific technology of 24-hour blood pressure monitoring should be fully used in the practice of hypertension diagnosis and treatment.
The so-called 24-hour blood pressure monitoring is a specific kind of dynamic blood pressure recorder worn on the upper limbs and chest of the subject, and the instrument automatically records the blood pressure of the subject for 24 hours at regular intervals to discover the changes in blood pressure during the subject’s daily activities (such as sports, exercise, work, life, rest and sleep).
Medical research has proven that human blood pressure fluctuates, and the fluctuations are regular, with 70% of hypertensive patients showing two peaks and valleys, the so-called “spoon blood pressure”. The first peak is around 8:00 a.m., after which the blood pressure begins to fall, and due to the noon lunch break, there is often a daytime blood pressure trough from 12:00 noon to 1:00 p.m.; after 2:00 p.m., the blood pressure begins to rise again, and around 6:00 p.m. the blood pressure is a big peak; then the blood pressure begins to fall, and the lowest point appears at 12:00 p.m. late at night, after which the blood pressure rises, and the peak appears again the next day. In 25% of patients, there was only an afternoon peak and no morning peak. In particular, a minority (5%) of hypertensive patients had only a morning peak and no daytime or afternoon peaks.
Thus, the method of ambulatory blood pressure monitoring can be satisfactorily resolved for both of these examples. Moreover, 24-hour blood pressure monitoring allows for early detection of hypertensive patients and detection of “white coat hypertension” and can also assist in identifying secondary hypertension.
Some patients with hypertension have elevated blood pressure only at 6 to 8 a.m. or 6 to 8 p.m. If they rely on occasional blood pressure measurements only during office hours (8 a.m. to 5 p.m.), it is easier to miss the diagnosis. Therefore, 24-hour ambulatory blood pressure monitoring should be performed in patients with suspected hypertension, or blood pressure should be measured at two peak blood pressure times to detect hypertensive patients in a timely manner.
There are also some hypertensive patients who are found to be hypertensive when tested in the physician’s office due to psychological factors or emotional stress, and whose blood pressure is difficult to control even after receiving several medications, showing characteristics of persistent hypertension. If these patients do not have high blood pressure when they observe themselves at home, and are found to have high blood pressure only in the hospital with 24-hour ambulatory blood pressure monitoring, and completely normal blood pressure after leaving the hospital, they are called “white coat hypertension”. Once these patients understand the cause of their high blood pressure, they will eliminate their nervousness and impatience and take the initiative to cooperate with the physician’s treatment. Timely detection of “white coat hypertension” patients, adjustment of their lifestyle and the appropriate choice of anti-hypertensive drug treatment, will get the desired therapeutic effect, which is of practical significance to reduce the patient’s financial burden and avoid unnecessary adverse drug reactions.
It is well known that in patients with untreated hypertension, a series of pathologies can occur in the heart, brain, kidney and other important organs, such as left ventricular hypertrophy, cardiac failure, coronary artery disease, cerebral thrombosis and cerebral hemorrhage. The incidence and severity of these conditions are highly correlated with blood pressure values, especially with the average 24-hour blood pressure and the average nighttime blood pressure, i.e., the higher the average systolic and diastolic blood pressure, the more severe the damage to the target organs. Some studies have shown that hypertensive target organ damage is rarely seen in those with mean ambulatory blood pressure values below 120/80 mmHg, while those with mean ambulatory blood pressure values above 160/100 mmHg experience varying degrees of hypertensive target organ damage.
The cardiac, cerebral, and renal effects are more severe in patients with nocturnal elevated blood pressure than in those with incidental elevated blood pressure. For example, patients with elevated nocturnal blood pressure are prone to develop left ventricular hypertrophy, which is an independent risk factor for the development of cardiovascular disease and death. Prevention and timely detection and reversal of left ventricular hypertrophy have been important advances in anti-hypertensive therapy in recent years. Therefore, those who are found to have elevated blood pressure at night by ambulatory blood pressure monitoring should do a good job of preventing and reversing left ventricular hypertrophy in order to further prevent the occurrence and development of coronary heart disease, cerebral thrombosis and cardiac failure.
The incidence of cerebrovascular disease increases significantly in older adults with a nighttime blood pressure drop rate greater than 20%. Therefore, 24-hour blood pressure monitoring, evaluation and prediction of the occurrence of cardiovascular diseases in the elderly, and timely measures for high-risk groups are important to protect the health and longevity of the elderly.
24-hour ambulatory blood pressure monitoring can detect hypertensive patients in a timely manner and assist in the diagnosis of secondary hypertensive diseases, enabling timely and rational treatment of all hypertensive patients. For patients with grade 2 or 3 (moderate or severe) hypertension, timely measurement of 24-hour average blood pressure, nighttime average blood pressure, range of blood pressure fluctuations and nighttime blood pressure drop rate, and timely adoption of comprehensive treatment measures mainly for blood pressure control will prevent the occurrence of heart, brain and kidney related diseases.
To control blood pressure during exercise or at the peak of blood pressure fluctuation to the desired level, ambulatory blood pressure monitoring should be fully applied to evaluate the efficacy of drugs and anti-hypertensive treatment regimens, especially in elderly patients or patients with grade 2 or 3 and recalcitrant hypertension, after receiving new drugs and new treatment regimens, it is best to use 24-hour ambulatory blood pressure monitoring to evaluate the efficacy.