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# Ambulatory blood pressure

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.

Studies are listed below supporting the thesis that ABPM is a far better method than clinical measurements.

## Nocturnal hypertension

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[1] and is a much better indicator than the daytime blood pressure reading.

## Target organ damage

It has been shown that end-organ damages related to hypertension, such as left ventricular hypertrophy, 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 [2].

## Morning surge

The day-night time fluctuates with values rising in the daytime and falling after midnight. With these changes, its 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 [3]. According to the American Heart Association, an excessive morning blood pressure surge is a predictor of stroke in elderly people with high blood pressure [4] [5].

This is based on the American Heart Association's calculation, using systolic blood pressure (SBP):

$Dip = 1 - \frac{sleep SBP}{Awake SB} *100%$
Range Class
<0% Reverse Dipper
0% - 10% Non-Dipper
10% - 20% Dipper
>20% Extreme Dipper

## Blood pressure variability

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

## References

1. ^ Use and interpretation of ambulatory blood pressure monitoring: recommendations of the British Hypertension Society
2. ^ Clinical Usefulnesses of Ambulatory Blood Pressure Monitoring, Paolo Verdecchia, Fabio Angeli, Roberto Gattobigio
3. ^ Monday Morning Surge in Blood Pressure May Lead to Increase in Cardiovascular Events, American Heart Association
4. ^ Morning surge in blood pressure linked to strokes in elderly
5. ^ Stroke Prognosis and Abnormal Nocturnal Blood Pressure Falls in Older Hypertensives