02/28/2008Blood Pressure - The complete scoop for CKD patients

Susan Steigerwalt, MD, FACP

High blood pressure (also called hypertension) damages the kidney's blood-filtering units so the blood doesn't get cleaned. Eventually, this type of damage can cause irreversible shutdown of the kidneys. Second to quitting smoking, the single best thing you can do for your kidneys and heart is to control your blood pressure.  This is a difficult challenge for patients with chronic kidney disease.  In fact, most kidney patients require four different medications to reach their blood pressure to goal.

What is a blood pressure reading?

A blood pressure reading consists of two numbers.  The top number is the systolic  reading.  This is the peak blood pressure at the beginning of the cardiac cycle.  The bottom number is the diastolic reading, the pressure when the heart is at rest.  These measurements are in millimeters of mercury (mmHg), just like a weather barometer.  An example of a blood pressure measurement is 140/80 mmHg, which translates to 140 for systolic blood pressure and 80 for diastolic blood pressure.  A normal office blood pressure is less than 135/85 with a pulse usually between 60-80 beats per minute (bpm) while at rest. Blood pressure tends to be lower in the evening and lowest when we are sleeping.  Blood pressure may vary by 50-70 mmHg for systolic and 20mmHg diastolic depending on when it is measured.

Monitor your blood pressure at home

Checking your own blood pressure is a great way to become involved with your care. We recommend that all patients buy a blood pressure cuff, learn to use it, and check their blood pressure as part of their daily routine.

There are many blood pressure cuffs available. We recommend three models that have been independently reviewed and tested:

• Good: ReliOn (Made by Omron, available for $50 at Wal-Mart) [web link]
  
• Better: HEM-712C ($50 at Costco & Amazon) [web link]
  
• Best: HEM-711AC with Intellisence ($60 at Costco and Amazon) [web link]
  

TIP: Regardless of which blood pressure device you buy make sure the blood pressure cuff is large enough. A cuff that is too small will give reading which are too high. People with large arms may need to order a large cuff from the manufacturer.

Once you have a blood pressure monitor, practice using it correctly:

• Avoid alcohol, caffeine and cigarettes for 30 minutes before measurement
• Measure your BP when you first wake and before dinner
• Sit in a chair with a back at a table or desk for 3-5 minutes prior to checking your blood pressure
• Rest your arm on the table while measuring the blood pressure.
• If the blood pressure is too high you may repeat the measurement once after resting for a few minutes.  Record the lower reading of the two.

We urge all of our patients to record their blood pressure readings and bring their log to the clinic. This information is very useful to your doctor.  They will instruct you on how often to measure your blood pressure and what time of day is best for optimal readings.

Ideal blood pressure - your goal

Patients with kidney disease need to keep their blood pressure below 130 over 80 when measured in the clinic. At home you should get blood pressures about 10 points lower (i.e. the top number should be less than 120).  It is less clear what the home reading should be compared to the clinic.  Some data suggests 130/80 is fine.  Getting your blood pressure to the target may be difficult and can take months but if we work together and we will get you to goal.

Change your diet to help control blood pressure

What you eat can affect your blood pressure. Salt or sodium can raise your blood pressure and your doctor may advise you to restrict the amount of salt in your diet. Restricting salt is more important if you have heart failure or are an African American.

The most effective way to lower your blood pressure with diet is by using the Dietary Approaches to Stop Hypertension Diet or DASH Diet (http://www.dashdiet.org/). The DASH Diet has been shown to lower blood pressure about as much as a typical blood pressure medicine. In addition the drop blood pressure can be expected after just two weeks of following this diet.

The DASH Diet is a high potassium, high calcium, and low fat diet. It does not restrict sodium; however if in addition to the DASH Diet you also restrict sodium your blood pressure will fall even more.

The DASH Diet is not for everyone. Some kidney patients have trouble with high potassium or phosphorous in the blood stream. The DASH Diet could make either of these problems worse. Ask your doctor if the DASH Diet would be a healthy choice for you.

Check with a specialist before taking new medications

Speak with your nephrologist or hypertension physician before beginning any new drugs.  Some over-the-counter medications (Motrin, Advil, Aleive, and others) or prescriptions from your primary care physician may have adverse affects on your kidneys.

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