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Circadian blood pressure variations and their impact on disease
Insights
Single clinic blood pressure measurements can overestimate readings due to patient anxiety. Twenty-four-hour blood pressure monitoring provides a more accurate assessment of hypertension and its complications.
Area of Science:
- Cardiology
- Hypertension Research
- Clinical Measurement
Background:
- Single clinic blood pressure measurements have limitations.
- Clinic blood pressure readings can be overestimated due to patient anxiety (pressor response).
- These measurements poorly reflect 24-hour mean blood pressure and circadian patterns.
Purpose of the Study:
- To highlight the limitations of single clinic blood pressure measurements.
- To emphasize the importance of 24-hour ambulatory blood pressure monitoring (ABPM).
- To discuss the relationship between blood pressure variability, mean blood pressure, and target-organ damage.
Main Methods:
- Review of existing cross-sectional investigations and clinical measurement principles.
- Comparison of single clinic measurements with 24-hour ambulatory blood pressure monitoring.
- Analysis of the correlation between blood pressure parameters and target-organ damage.
Main Results:
- Single clinic measurements show limited correlation with mean 24-hour blood pressure.
- Hypertension complications are more closely related to the 24-hour mean blood pressure than casual measurements.
- Blood pressure variability and nighttime blood pressure are independently related to target-organ damage.
Conclusions:
- Twenty-four-hour ambulatory blood pressure monitoring offers a more comprehensive assessment of hypertension.
- Antihypertensive treatment must effectively manage blood pressure both day and night to prevent complications.
- Relying solely on clinic blood pressure measurements can lead to misclassification and inadequate treatment.
Abstract:
Errors can be made when blood pressure is measured only by a single clinic measurement. Such assessments bear only a limited relationship to mean 24-h blood pressure and do not provide complete information on potentially important features of the circadian pattern of blood pressure. Measurement of clinic or "casual" cuff blood pressure by the doctor can produce a large, variable, and unpredictable overestimation caused by the pressor response associated with anxiety in the patient. Single cuff measurements rarely reflect the 24-h mean and classifications of severity based on cuff measurements are therefore subject to a large degree of overlap. Estimation of the response to antihypertensive treatment by casual cuff measurements is therefore subject to the same criticisms. Although superiority of measurement of 24-h mean blood pressure has not been demonstrated in any prospective controlled study, several cross-sectional investigations have shown that complications of hypertension relate more closely to the 24-h mean than to casual measurements. The degree of variability of blood pressure during a 24-h period (which can only be measured by 24-h monitoring) bears a relation to target-organ damage that is independent of mean blood pressure value. Nighttime blood pressure mean has been shown to correlate with target organ damage approximately as closely as daytime blood pressure mean, implying that antihypertensive drugs must act during the night as well as the day if they are to influence the complications of hypertension.