Ambulatory blood pressure

Definition

Ambulatory blood pressure is blood pressure measurements taken throughout the day and night while an individual is engaged in normal daily activities.

Purpose

Ambulatory blood pressure measurement, also known as automated sphygmomanometry, is used to measure blood pressure at regular intervals, usually throughout a 24 hour period. Ambulatory blood pressure is believed to be a more accurate indicator of certain high blood pressure problems than a single reading taken in a doctor's office.

Ambulatory blood pressure monitoring is used to diagnose and get a better picture of a variety of conditions. One of the most frequent reasons for use is to diagnose “white coat hypertension.” This is name for the fact that many people have increased blood pressure due to the stress of being at the doctor's office. During routine blood pressure measurement in health care settings their blood pressure is recorded as being much higher than it really is normally. Monitoring the blood pressure through the day can help to determine if elevated blood pressure levels are a side-effect of the office visit or are true hypertension .

As many as 30% of pregnant women are believed to have white coat hypertension. Using ambulatory blood pressure monitoring can help reduce the need to administer medicine, admit the woman to the hospital, or deliver the baby early when hypertension is not truly present. Ambulatory blood pressure monitoring is also used frequently to help diagnose seniors with hypertension. Because many seniors experience significant adverse side-effects to blood pressure lowering medications, using a series of blood pressure measurements throughout the day to make the most accurate diagnosis possible can help eliminate the unnecessary treatment of hypertension.

Precautions

There are no special precautions necessary for having ambulatory blood pressure monitored. The device must be worn for the whole 24 hour period, so certain activities such as bathing or swimming should not be planned for that time period.

Description

Ambulatory blood pressure measurement is done using an ambulatory blood pressure monitor. The monitor consists of a blood pressure cuff, just like the ones normally used to take blood pressure readings in the doctor's office. This cuff is then attached to a small, battery-powered machine that is normally worn clipped to a belt. The machine sends information to the cuff about when to inflate and deflate, takes the blood pressure readings, and records it so that the doctor can look at the information later.

The ambulatory blood pressure measurement device records the individual's blood pressure at regular intervals usually every 15 or 30 minutes as decided by the doctor. Some machines have the option for the individual to cause extra readings to be taken between intervals as desired. The monitor stays on the individual all day, and throughout the night. After the 24 hour period of monitoring is complete the individual returns to the doctor's office where the data is taken from the monitoring device and analyzed.

Preparation

No special preparations are required for ambulatory blood pressure measurement.

Aftercare

No aftercare is generally required for ambulatory blood pressure.

KEY TERMS

Automated sphygmomanometry —The automatic taking of blood pressure readings at regular intervals.

QUESTIONS TO ASK YOUR DOCTOR

• How often will the monitor take measurements?
• What types of information should I note in my diary?
• Are there any activities I should not engage in while wearing the monitor?
• Is there a phone number to call if I have questions or problems with the monitor?

Complications

The individual may find that the arm on which the blood pressure cuff was worn is somewhat sore from the repeated blood pressure measurements. Some individuals experience a minor rash. Both of these issues generally clear up without treatment in a short time after the blood pressure cuff is removed.

Results

Normal blood pressure levels differ between people and during different times of the day. Healthy individuals normally have a significant dip in blood pressure during the late hours of sleep. Absence of this dip is a sign of some significant health problems. Ambulatory blood pressure results are often averaged over the waking hours or over the whole day. Results are:

• Normal (normotensive): less than 120/80.
• Pre-hypertensive: 120/80 to 139/89.
• Stage 1 hypertensive: 140/90 to 159/99.
• Sate 2 hypertensive: greater than 160/100

Caregiver concerns

The doctor makes the decision that ambulatory blood pressure monitoring is appropriate for the patient. The doctor or nurse explains the use of the device to the individual, including how often the device will take readings, what they will feel like, and how to manually deflate the blood pressure cuff. The doctor or nurse will also discuss with the patient what types of information should be recorded in the diary. The doctor or a specially trained office staff member uses a computer to interpret and summarize the data. The doctor then uses this data to determine which, if any, further action is indicated.

Resources

BOOKS

Appel, Lawrence, Rafael H. Llinas, and Simeon Margolis. Hypertension and Stroke. Baltimore, MD: Johns Hopkins Medical Institutions, 2003.

Fortmann, Stephen P. and Prudence E. Breitrose. The Blood Pressure Book: How to Get it Down and Keep it Down. Boulder, CO: Bull Pub. Co., 2006.

White, William B., ed. Blood Pressure Monitoring in Cardiovascular Medicine and Therapeutics, 2nd Ed. Totowa, N.J.: Humana Press, 2007.

PERIODICALS

Chavanu, Kathleen, Jennifer Merkel and Allen M. Quan.

"Role of Ambulatory Blood Pressure Monitoring in the Management of Hypertension." American Journal of Health-System Pharmacy 65.3 (Feb 1, 2008): 209-219.

Daniels, Stephen R. “Ambulatory Blood Pressure and Cardiac Abnormalities.” Journal of Pediatrics 152.3(March 2008): A2.

Recordati, Giorgio and Alberto Zanchetti. “The 24 h Blood Pressure-R-R Interval Relation in Ambulatory Monitoring.” Autonomic Neuroscience: Basic and Clinical 139 1-2 (May 30, 2008): 68-78.

ORGANIZATIONS

American Academy of Family Physicians, P.O. Box 11210, Shawnee Mission, KS, 66207-1210, 800-274-2237, http://www.aafp.org/.

Robert Bockstiegel