Ambulatory blood pressure monitoring – (ABPM) is a diagnostic tool used to measure the arterial pressure at regular intervals during a 24 hour period. To do this the patient wears a normal blood pressure cuff connected to a small registration device attached with a belt to the waist. The blood pressure is then measured automatically throughout the day and recorded in the device. The patient must simply continue his normal daily activities but avoid physical exertion during the testing period.
ABPM has many clinical applications, including but not limited to the diagnostic assessment of Hypertension, White coat Hypertension and the determination of the nocturnal pressure profile.
From the analysis of the data recorded during the 24 hours of blood pressure monitoring patients are subdivided into different groups based on their nocturnal pressure profile.
The normal physiological response at night is for blood pressure to decrease, known as “dipping”.
A “dipper” is defined as a patient demonstrating a 10-20% decrease in the average systolic pressure during the night as compared to the average value during the day.
A “non-dipper” is defined as a patient demonstrating less than 10% decrease in the average systolic pressure during the night as compared to the average value during the day.
A “reverse-dipper” is a defined as a subject demonstrating an increased average systolic pressure during the night as compared to the average value during the day. These patients therefore have irregular physiology in respect to the normal circadian rhythm of blood pressure.
Night nipping can be influence by many factors, such as sleep quality, or of more concern, pathological conditions such as secondary causes of hypertension, chronic renal failure, heart failure influence.
According to numerous clinical studies the non-dipper nocturnal pressure profile seems to be associated with more severe organ damage, such as left ventricular hypertrophy, and to a worst prognosis in patients.
Another extremely important evaluation is measuring “morning surge”, the physiological increase of the arterial pressure when a patients awakes in the morning. Data collected by the 24 hour registration by the ABPM will enable the quantification of this value.
The American Heart Association findings agree that the “morning surge“ value has significant prognostic and clinical relevance, specifically that an excessive increase in blood pressure in the morning is a predictor of increased risk of acute vascular events, and in particular of ischemic stroke in the elderly suffering from high blood pressure.
Furthermore, it has been demonstrated that the level of organ damage in hypertensive patient correlates more strongly with the data collected via ABPM than with the clinical blood pressure.