Chapter 3
Circulatory System

The blood leaves the capillaries by way of the veins. Veins return blood to the right side of your heart, where the whole cycle begins again. (See figure 3.2.)

 
Blood Pressure and How It’s Regulated

Blood pressure is a measure of the force with which your blood goes through your blood vessels. It is basically determined by two things:
1. How well your heart can pump blood out.
2. How much tension there is in your arteries.

There is a wide range of blood pressures that are considered normal. A stable blood pressure is one that stays within a consistent range.

Your nervous system controls the diameter of your blood vessels. The diameter is always adjusting in size depending on your body position and level of activity. This helps keep your blood pressure stable. For example, when you move from sitting to standing, the blood vessels in your legs narrow to stabilize blood pressure. If this did not occur, blood would stay in your legs rather than return to your heart. This pooling of blood in your legs would cause your blood pressure to lower.

 
HOW SCI AFFECTS YOUR CIRCULATION

The major effects that your spinal cord injury has on your circulation are changes in your blood pressure and in how your blood moves from your body back to your heart. How well your heart pumps is not affected by SCI but the tension in your arteries is.

As mentioned above, your nervous system plays a part in adjusting the diameter of your arteries. So, the arteries in the parts of your body affected by your injury will also be affected.

A narrow artery raises blood pressure, while a wider artery lowers the pressure. Think in terms of a garden hose. At the tap, you turn on the water and let it flow at a steady rate. Depending on how you use the nozzle, you can close it down and increase the resistance, sending less water through in a high-powered, direct stream. You can also open the nozzle all the way and decrease the resistance, which will give you a lot of water in a relaxed spray with no strong power behind it.

Increasing the blood pressure is like closing down the nozzle. Lowering the blood pressure is like opening up the nozzle so that the power behind the water is little more than what originally comes from the tap. By closing down the nozzle just enough, you can take the original power behind the water, force it through a smaller space, and increase the power and speed at which it comes out. You can then shoot down your neighbor’s prize roses at 40 paces!

In the same way, a stable blood pressure is high enough to circulate nutrients and oxygen to your body quickly and efficiently but not so high as to cause you problems.

After SCI, your arteries tend to stay wide (dilated). They can’t get as narrow (constricted) as they did before your SCI. The result is that your blood pressure stabilizes at a lower level than it was before your injury.

Usually, the action of your muscles, flexing and relaxing either voluntarily or during spasticity, helps keep your blood moving. The muscles affected by your injury can’t do this any more, although spasticity can help somewhat.

These changes in your circulation after SCI tend to increase your risk for developing the following conditions:

1. Edema (swelling)
2. Thrombus/pulmonary embolus (blood clots)
3. Orthostatic hypotension (low blood pressure when you sit up)
4. Decreased heart rate

 
Edema (swelling)

Depending on the level of your injury, your legs and perhaps your hands may swell. Swelling occurs when fluid leaves your blood vessels and goes into the spaces between tissue cells. This swelling is called "dependent edema". (Dependent refers to any area that is below the level of your heart). This edema is caused by muscle weakness in your legs or arms, because muscle action and movement normally help return blood to your heart. If the blood returns to the heart too slowly, more fluid will leak out of the blood and into the spaces between tissue cells.

To prevent your legs from swelling, you can do the following:

1. Wear stockings routinely. These are tight elastic stockings and should generally come up to the top of your thigh. They help in returning blood to your heart and keeping it from pooling in your legs.
2. Do your range-of-motion exercises every day, and make sure that you move your legs from one position to another every two to three hours.

If the swelling is only in one of your legs, see the next section because you may have a blood clot in your leg! If both your legs swell, try these tips for decreasing edema:

1. Do more range-of-motion exercises. Do them routinely or get someone else to do it for you.
2. Elevate your legs to or above the level of your heart for 10 to 15 minutes. Do this four to five times a day. Here are some ways to do this:
   • Lie down and place pillows under your feet and calves and/or under your hands and arms.
   • Move you wheelchair close to your bed and place your feet and legs on the bed. LOCK YOUR WHEELCHAIR FIRST!
   • Sit on a couch or an overstuffed chair and place your feet and legs on your wheelchair.
   • Sleep with your legs slightly elevated.
3. Make sure you wear your compressive stockings while you are awake and up in your chair.
4. If the swelling continues in your legs for more than one week despite your efforts to treat it or if you notice a sudden increase in swelling, call your physician at the SCI center or in your community.

 
Thrombus or DVT (blood clot)

Blood clots in either your legs or your lungs can be a serious medical problem. Blood has a tendency to clot when it does not move at its regular, steady pace. The same lack of muscle pumping action in your legs that causes swelling slows the blood and allows clots to form. Blood clots begin in veins, especially those in your legs. If it’s in one of the veins deep inside your leg, it is called a "DVT" (deep vein thrombus). (See figure 3.3.) A blood clot in the leg veins can break free and travel to other parts of your body. A clot that stays in one place is a thrombus (plural = thrombi). A clot that has broken free is called an embolus (plural = emboli).

Since blood clots are so common, your doctors often use drugs and other treatments to try and prevent them. First, the same things used to treat swelling (listed above) are started. Your doctor might also put you on medication that will decrease clot formation. These drugs are commonly known as "blood thinners" or anticoagulants (ANN-tie-co-AGG-you-lance). The most common type of drug used to prevent blood clots is called heparin. There are different types of heparin that have names like enoxaparin, Lovenox, and low molecular weight heparin. Sometimes doctors also use plastic air pumps on the legs to prevent blood clots. The part that goes around the leg inflates with air. This pushes the blood out of the legs and back toward the heart. These treatments decrease the risk of blood clots, but some people will get blood clots even if they receive the drugs and other treatments.

Some common signs and symptoms of a clot in your leg include:

1. One calf or thigh feels warmer than the other. It may also be red.
2. One calf or thigh is more swollen than the other. A simple way to see if there might be swelling is to measure the size of both calves or thighs. A clot can develop and cause the leg to swell quickly. This is why, in the early stages after your injury, the nursing staff measure the size of your calves and thighs. You may wish to continue this practice on a weekly basis at home.
3. One leg may be painful, tender, or feel heavy. However, you may not have normal feeling in your legs, so you may not feel anything.

Often when there is a blood clot, you cannot tell you have one and neither can your doctors without doing special tests.

What to Do if You Think You Have One

1. If one calf or thigh becomes larger than the other,
   • DO NOT increase your activity level.
   • DO NOT do range-of-motion exercises.
   • DO NOT move the leg. Increasing your activity may cause the clot to break loose.
2. Put yourself to bed and call your physician or nurse at the spinal cord center to get further instructions. If you do have a clot in your leg, treatment will be geared toward preventing it from breaking free and moving to your lungs.
3. Most people with a blood clot must take anticoagulants for three to six months after the clot is discovered.

You may feel one or all of the following:

1. A sudden shortness of breath. It may be accompanied by a feeling of tightness in your chest.
2. Pain in your side, chest, or back. The pain is usually worse when you breathe in and lets up when you breathe out.
3. A sudden development of a new cough. This cough is often associated with sputum or phlegm that may be slightly pink or red.

Prevention is extremely important, because a pulmonary embolus can be life-threatening. Since most pulmonary emboli are caused by clots in the legs, the way to prevent them is to follow the prevention methods given to you under prevention of blood clots.

What to Do if You Think You Have a Pulmonary Embolus

1. CALL 911. A pulmonary embolus is an emergency!
2. Also call your spinal cord center physician or your local physician immediately.
3. If you feel short of breath, sit up in a chair; this sometimes helps.
4. This problem needs to be treated in a hospital where further tests and treatments can be performed.

If you get a blood clot in your leg, or if it goes into the lung, you will usually receive blood thinners to help your body dissolve the blood clot. The most common blood thinners are heparin and warfarin (Coumadin). The main side effect of these drugs is bleeding. Bleeding can be minor, like a nosebleed, or serious, like a bleeding stomach ulcer. Because of these risks, people on blood thinners need close medical follow-up. Sometimes frequent blood tests are needed to make sure you are receiving the right dose of the blood thinners. Some of these medicines can interact with other drugs, or even with food. You should ask for information about these interactions if you need to take blood thinners after leaving the hospital. Usually a pharmacist will discuss this with you if you need blood thinners.

 
Orthostatic Hypotension

Your blood pressure may be lower after an SCI, because your blood vessels cannot constrict to help keep it at a higher level. Most people get used to a lower blood pressure and do not have problems from it.

However, when you sit up with your legs down or when you stand up, your blood pressure may drop even lower. This happens because blood tends to collect (pool) in the veins of your legs and feet instead of being pushed back to the heart. If your blood pressure drops when you are upright, it is called orthostatic hypotension. Orthostatic means "changing positions", and hypotension refers to lower blood pressure.

Lower blood pressure can decrease the amount of blood to your brain. This makes you feel lightheaded or dizzy when you change positions. This can be a big problem soon after your SCI when you first get out of bed. Fortunately, this problem usually improves with time in most people.

Preventing Lightheadedness or Dizziness

1. When you get up from a lying position, do it in steps:
   • Sit up slowly.
   • Rest for a few minutes.
   • Move your legs to a lower position.
   • Continue your activities.
2. Do not change positions quickly. Take your time.
3. Wear your compressive stockings and abdominal binder (if prescribed), because they help blood get back to your heart and help prevent blood from collecting in your legs.

If you have a continuing problem with dizziness, you can try the following:

1. Make sure that you are taking in enough fluids in your diet.
2. If you continue to feel dizzy or lightheaded despite following all the tips outlined above, call your SCI clinic physician or nurse. You may need to be put on medications to increase your blood pressure for a while.

Your blood pressure can go so low that not enough blood gets your brain and you pass out, or faint. Fainting should not cause problems if it happens once in a while. If it does occur more often, you need to be treated to prevent it.

If You Faint or Feel Dizzy

1. Your family or attendant should lie you down and elevate your legs to above the level of your heart.
2. If you are in your wheelchair, someone can just tilt the wheelchair backwards about 45 degrees. Be sure to lock your brakes first.

 
Decreased Heart Rate

After an injury to the spinal cord, your heart rate will tend to be slower. The same part of the nervous system that is responsible for increasing your blood pressure is also responsible for increasing your heart rate. The ability may be lost if your injury is above the mid-thoracic level. If you cannot raise your heart rate when you need to, such as when exercising, you may have the same feelings of dizziness and lightheadedness that were mentioned in the section on orthostatic hypotension.

What Will You Feel if You Have Decreased Heart Rate?

Most people don’t feel any differently with decreased heart rate. Some people, though, may feel dizziness and lightheadedness if their heart rate drops below 50 beats per minute.

If you feel lightheaded or dizzy, call your SCI clinic for further instructions.

It’s a good idea to memorize your usual blood pressure and heart rate. That way, if you are treated by different doctors who don’t have your medical records, you can tell them what is a normal blood pressure and heart rate for you. Otherwise, they may think you have a new medical problem causing low blood pressure or pulse.

 

SCI Self-Care Guide Main Page Chapter 1     SCI Anatomy & Physiology Chapter 2     Skin Care Chapter 3     Circulatory System Chapter 4     Respiratory Care Chapter 5     Range of Motion Chapter 6     Bladder Management Chapter 7     Bowel Management Chapter 8     Nutrition Chapter 9     Medications Chapter 10   Nerves, Muscles, and Bones Chapter 11   Autonomic Dysreflexia Chapter 12   Pressure Sores Chapter 13   Psychosocial Adjustment Chapter 14   Sexual Health & Rehabilitation

Chapter 15   Community Resources Chapter 16   Vocational Rehabilitation Chapter 17   Recreation Chapter 18   Driver’s Training Chapter 19   Attendant Management Chapter 20   Home Modifications Chapter 21   Approaching Discharge Chapter 22   Pain after Spinal Cord Injury Chapter 23   Substance Abuse and SCI Chapter 24   Exercise Chapter 25   Alternative Medicine Chapter 26   Equipment Chapter 27   Staying Healthy Glossary