Ambulatory blood pressure monitoring (ABPM) is generally not accurate in patients with certain forms of abnormal heart rhythms (arrhythmias), such as atrial fibrillation, frequent extrasystoles or frequent episodes of supraventricular tachycardiasupraventricular tachycardia. Readings may be less accurate for elderly patients or those with very high blood pressure. These problems with accuracy are usually detected when the monitor is being placed on the patient because calibration may be difficult or impossible.


It is important to note that ABPM readings have not been as carefully researched and documented as the use of clinic blood pressure readings. For instance, medications that have been proven to reduce blood pressure and death rates from hypertension-related illnesses are usually officially evaluated with the use of clinic blood pressure readings. Though ABPM is becoming increasingly popular as a method of evaluating medications and other treatment options during clinical trials, the majority of information available applies to clinic blood pressure readings.

There are very few safety issues associated with ABPM, and complications are rare. Bruising or swelling of the arm around the cuff area may occur in some patients, especially those with impaired function of blood platelets (substances that help the blood to clot in response to injury). Skin inflammation or rash may also develop. In very rare cases, the repeated pressure on the arm can cause palsy (or paralysis) of the ulnar nerve, which affects movement and sensation in the wrist and hand.