Ambulatory Blood Pressure Monitoring
What is Ambulatory Blood Pressure Monitoring?
All of us have experienced the anxiety associated with a visit to the Doctor’s clinic. It is this very same anxiety, which increases the blood pressure in a clinic setting and often mistakenly labels the patient as hypertensive. Ambulatory blood pressure (ABP) monitoring is a technique where numerous readings of the patient’s blood pressure are taking with a portable device over a 24-hour period or longer, while the patient carries out his routine daily activities. It provides accurate and reliable information and can give patient and the doctor a truer picture of the blood pressure than the occasional readings taken at doctor's office.
What are the indications?
Clinical Problems in Which Ambulatory Blood Pressure Monitoring Is Useful
- "Office" or "white-coat" hypertension- Patients with persistently elevated blood pressures during standard clinic visits and normal self-measurements elsewhere
- Borderline hypertension with target organ (like heart, kidney, retina) damage- The correlation of blood pressure load with the development of target organ complications can be addressed with ABP monitoring.
- Assessment of adequate control of BP while on antihypertensive medications.
- Episodic hypertension
- Evaluation of blood pressure changes in nocturnal angina, pulmonary congestion
- To diagnose a low blood pressure on medication
The term "office" or "white coat" hypertension applies to patients who have elevated blood pressure only when they are in the doctor's office. Blood pressure in these patients is normal when self-measurements are taken-for example, at home and work. "Office" hypertension may persist for several months or many years, despite the individual's growing familiarity with office procedures and personnel. It not only confirms the hypertensive response in the clinic or doctor's office, but also can assess whether or not other stressful periods elevate blood pressure. In the majority of patients with "office" hypertension, blood pressures are not elevated during other forms of regularly recurring stress such as work.
How is this test performed?
The typical, fully automatic device for ABP monitoring is battery-driven and consists of an arm cuff also. The cuff is tied around the patient’s arm after localizing the maximal pulsations of the brachial artery on the arm by the doctor. This device is programmed to inflate automatically every 15-20 minutes throughout the 24 hour period. Usually the blood pressure will be measured at 15 to 20 minute periods during the day and every 30 minutes to one hour at night. The data is stored and then analyzed with computer software and interpreted by doctors.
To assure that the readings taken by the device are valid, simultaneous determinations of blood pressure by the doctor using a mercury sphygmomanometer and by the device are done before initiating the monitoring.
What are pre or post test instructions?
There are no risks involved with the use of ultrasound waves and the transducer and there are no contraindications for this test.
- There are no special diet restrictions before, during or after the test.
- Carry on with the routine activities, diet and medications. Excessive manual work or use of the arm on which the cuff is tied is to be avoided.
- It is better to avoid driving that day
- Each time the cuff inflates completely, it starts deflating immediately and should be fully deflated within a minute or two. If the cuff fails to deflate, it indicates some technical fault and then one should unwrap the cuff and come back to us.