Blood Pressure Measurement

Ambulatory Blood Pressure Measurement

Ambulatory blood pressure monitoring (ABPM) measures blood pressure at regular intervals throughout the day and night. It is believed to be able to reduce the white coat hypertension effect (high blood pressure in the clinic but normal at home). Studies are supporting the thesis that ABPM is a far better method than clinical measurements.

Ambulatory blood pressure monitoring allows blood pressure to be continually monitored during sleep, and is useful to determine whether the patient is a dipper or non-dipper, that is to say whether or not blood pressure falls at night compared to daytime values. A night time fall is normal. Absence of a night time dip is associated with poorer health outcomes. In addition, nocturnal hypertension is associated with end organ damage and is a much better indicator than the daytime blood pressure reading.

It has been shown that end-organ damages related to hypertension, such as left ventricular hypertrophy and narrowing of the retinal arteries are more strongly associated with ABPM than with a clinical BP measurement, the reason being clinical BP measurement are referred to the marked variability of BP measurement and white coat effect.

The day-night time fluctuates with values rising in the daytime and falling after midnight. With these changes, it is possible to calculate the BP dip, with categories such as non-dipper (<10%), dipper, extreme dipper, and reverse dipper. Independent studies have shown that for subject with blunted or abolished fall dip and abnormal ABP result in higher incidences of LV hypertrophy and CV mortality. An excessive morning blood pressure surge is a predictor of stroke in elderly people with high blood pressure.

24-hour, non-invasive ambulatory blood pressure monitoring allows estimates of BP variability.