Ambulatory blood pressure recording; principles and practice

Continuous intra-arterial blood pressure recording in ambulant subjects was initially developed in 1969. This involves the use of arterial cannulation and a perfusion unit with either data recording on magnetic tape or the use of biotelemetry. This technique produces a very large amount of accurate data (approximately 100,000 data points during a twenty-four hour period) but is invasive and is therefore not suitable for routine clinical use or the study of normal subjects. The major clinical use of ambulatory blood pressure recording is the investigation of patients with mild hypertension when it is not clear whether the degree of blood pressure elevation warrants treatment. In primary health care mild hypertension is common, whereas severe hypertension, where the decision to treat is easy, is relatively uncommon. Some patients exhibit “white coat hypertension” with persistently elevation blood pressure when measured in the clinic or doctors surgery, but a normal ambulatory blood pressure outside the hospital or clinical environment. These individuals have a good prognosis and may not require drug therapy. Ambulatory blood pressure monitoring may also be useful in the investigation of episodic or resistant hypertension and is also useful in the assessment of blood pressure treatment and drug trial evaluation