Subject: Living With Parkinson's Disease: Understanding and Managing Low Blood Pressure

Date: 10/25/2006

Most people think of PD as shaky hands (tremor), stiffness (bradykinesia), slow movements (bradykinesia), and trouble with balance or walking (postural instability). However, PD can also lead to many other challenges. These include constipation, trouble with controlling or emptying the bladder, difficulty swallowing, excessive sweating, sexual difficulties, and control of blood pressure. All of these problems—known as nonmotor symptoms—are related to a part of the nervous system called the autonomic nervous system. This article focuses on problems with blood pressure that is too low when you stand up or sit up after lying down, called orthostatic hypotension. Future articles will address other nonmotor symptoms of PD.

What is blood pressure?
Blood pressure is the force created by your blood against the walls of the blood vessels that carry blood away from your heart. When healthcare professionals check your blood pressure, they usually record two numbers in the form of XXX/XX, for example, 137 over 75. These numbers represent the pressure when your heart is squeezing and pumping the blood through your body (systolic blood pressure) over the pressure when your heart is at rest between beats (diastolic blood pressure). Your blood pressure should ideally be less than 120/80, but not too low. To get an accurate reading, your blood pressure should be checked about five minutes after you lie down, when you're sitting, when you first stand up, and about one to two minutes after you stand up.

Your blood pressure depends upon many different things, including
* How well your regulatory system and autonomic nervous system are working
* Air temperature
* Whether you have been drinking enough fluids
* Whether you are standing, sitting, or lying down
* How long you've been sitting or lying down

What is orthostatic hypotension and what causes it?
Because of gravity, your blood tends to pool in the veins of your legs when you stand up. Your body responds to this pooling by increasing your heart rate and squeezing or constricting the blood vessels to send the blood to your brain and other vital organs. If you have orthostatic hypotension, something interferes with your body's response. Instead of increasing, your blood pressure falls 20 or more points when you stand up or when you sit up after lying down. Another problem in people with PD is a similar fall in blood pressure that occurs soon after you eat a large meal. This is called postprandial hypotension.

Some people have a combination of high blood pressure when they are lying down and low blood pressure when they are standing up. This type of problem is particularly difficult to treat. You will need to work closely with your doctor to find ways to regulate your blood pressure if you have this problem.

A number of things can cause orthostatic hypotension in people with PD. These include underlying problems with the autononmic nervous system and side effects of medicines used to treat PD.

How can orthostatic hypotension be treated in someone with PD?
People who have orthostatic hypotension and PD should keep in mind some simple points:
* Drink plenty of water.
* Eat five or six small meals throughout the day rather than two or three large meals.
* Use more salt on your food (check with your doctor before doing this if you have the combination of orthostatic hypotension and high blood pressure when lying down).
* Wear thigh-high compression stockings that gently squeeze your legs to prevent the pooling of blood in your legs.
* Don't sit with your legs crossed.
* Stand up slowly after you have been sitting.
* Sit up slowly after you have been lying down, and sit on the side of the bed for a few minutes before standing to let your body adjust to the new position.
* Use blocks to raise the head of your bed about 10 to 20 degrees.

If necessary, there are also medicines that the doctor can order for you to raise your blood pressure. If you find that you are having problems with dizziness, lightheadedness, or even fainting, make sure that you discuss this with your doctor. Working together, communicating about orthostatic hypotension, and finding solutions will help you have a better quality of life with PD.

The Autonomic Nervous System
The autonomic nervous system (ANS) is the part of the nervous system that controls the involuntary functions of your body. These functions, which happen without you thinking about them or "making them happen," include heart rate, breathing, blood pressure, the breakdown of the food that you eat (digestion), and others. Although you're not often aware of it, the ANS is constantly regulating glands and muscles through the release or uptake of chemicals that control the messages that nerve cells use to communicate with each other.

The ANS is made up of three parts: the sympathetic, parasympathetic, and enteric systems. The sympathetic nervous system prepares your body for emergencies or times of stress. This part of the ANS is responsible for your body's "fight or flight" response when you are faced with a dangerous situation. During this response, your heart rate and blood pressure increase, the pupils of your eyes get bigger, and your digestive system slows down. The parasympathetic system helps your body's functions return to normal after they have been stimulated by the sympathetic nervous system and also helps your body to fight off or respond to infections. The enteric nervous system is made up of nerve fibers that send signals to your stomach, intestines, pancreas, and gall bladder. After you eat, these nerve fibers send signals to your brain to drive more blood to this area of your body to help process or digest your food.

E-MOVE Editor: Richard Robinson, NASW, WE MOVE

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