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2008/04/18, 08:17 AM
I am taking excerpts from this site :
http://www.medicinenet.com/low_blood_pressure/page3.htm
"What are low blood pressure signs and symptoms?
When the blood pressure is not sufficient to deliver enough blood to the organs of the body, the organs do not work properly and may be permanently damaged. For example, if insufficient blood flows to the brain, brain cells do not receive enough oxygen and nutrients, and a person can feel lightheaded, dizzy, or even faint. Going from a sitting or lying position to a standing position often brings out symptoms of low blood pressure. This occurs because standing causes blood to "settle" in the veins of the lower body, and this can lower the blood pressure. If the blood pressure is already low, standing can make the low pressure worse, to the point of causing symptoms. The development of lightheadedness, dizziness, or fainting upon standing caused by low blood pressure is called orthostatic hypotension. Normal individuals are able to compensate rapidly for the low pressure created by standing with the responses discussed previously and do not develop orthostatic hypotension.
When there is insufficient blood pressure to deliver blood to the coronary arteries (the arteries that supply blood to the heart's muscle), a person can develop chest pain (angina) or even a heart attack. When insufficient blood is delivered to the kidneys, the kidneys fail to eliminate wastes from the body, for example, urea and creatinine, and an increase in their levels in the blood occur (for example, elevations of blood urea nitrogen or BUN and serum creatinine, respectively).
Shock is a life-threatening condition where persistently low blood pressure causes organs such as kidney(s), liver, heart, lung, and brain to fail rapidly.
What are the causes of low blood pressure?
Conditions that reduce the volume of blood, reduce cardiac output (the amount of blood pumped by the heart), and medications are frequent causes of low blood pressure.
Dehydration is common among patients with prolonged nausea, vomiting, and diarrhea. Large amounts of water are lost when vomiting and with diarrhea, especially if the patient does not drink adequate amounts of fluid to replace the depleted water.
Other causes of dehydration include exercise, sweating, fever, and heat exhaustion, or heat stroke. Individuals with mild dehydration may experience only thirst and dry mouth. Moderate to severe dehydration may cause orthostatic hypotension (manifested by lightheadedness, dizziness, or fainting upon standing). Protracted and severe dehydration can lead to shock, kidney failure, confusion, acidosis (too much acid in the blood), coma, and even death. For more, please read the Dehydration article.
Moderate or severe bleeding can quickly deplete an individual's body of blood, leading to low blood pressure or orthostatic hypotension. Bleeding can result from trauma, surgical complications, or from gastrointestinal abnormalities such as ulcers, tumors, or diverticulosis. Occasionally, the bleeding may be so severe and rapid (for example, bleeding from a ruptured aortic aneurysm) that it causes shock and death rapidly.
Severe inflammation of organs inside the body such as acute pancreatitis can cause low blood pressure. In acute pancreatitis, fluid leaves the blood vessels to enter the inflamed tissues around the pancreas as well as the abdominal cavity, depleting the volume of blood.
Causes of low blood pressure due to heart disease
Weakened heart muscle can cause the heart to fail and reduce the amount of blood it pumps. One common cause of weakened heart muscle is the death of a large portion of the heart's muscle due to a single, large heart attack or repeated smaller heart attacks (please read the Heart Attack article for more information). Other examples of conditions that can weaken the heart include medications that are toxic to the heart, infections of the muscle of the heart by viruses (myocarditis), and diseases of the heart's valves such as aortic stenosis.
Pericarditis is an inflammation of the pericardium (the sac surrounding the heart). Pericarditis can cause fluid to accumulate within the pericardium and compress the heart, restricting the ability of the heart to fill and pump blood.
Pulmonary embolism is a condition in which a blood clot in a vein (deep vein thrombosis) breaks off and travels to the heart and eventually the lung. A large blood clot can block the flow of blood into the left ventricle from the lungs and severely diminish the blood returning to the heart for pumping. Pulmonary embolism is a life-threatening emergency. For more, please read the Deep Vein Thrombosis and Pulmonary Embolism article.
A slow heart rate (bradycardia) can decrease the amount of blood pumped by the heart. The resting heart rate for a healthy adult is between 60 and 100 beats/minute. Bradycardia (resting heart rates slower than 60 beats/minute) does not always cause low blood pressure. In fact, some highly trained athletes can have resting heart rates in the 40s and 50s (beats per minute) without any symptoms. (The slow heart rates are offset by more forceful contractions of the heart that pump more blood than in non?athletes.) But in many patients bradycardia can lead to low blood pressure, lightheadedness, dizziness, and even fainting."
There are more causes listed like medication, postural hypotensions, neurological damage, adrenal damage and severe allergic reactions.
As far as treatment -
"Low blood pressure in healthy subjects without symptoms or organ damage needs no treatment. However, all patients with symptoms possibly due to low blood pressure should be evaluated by a doctor. (Patients who have had a major drop in blood pressure from their usual levels even without the development of symptoms also should be evaluated.) The doctor needs to identify the cause of the low blood pressure because treatment will depend on the cause. For example, if a medication is causing the low blood pressure, the dose of medication may have to be reduced or the medication stopped, though only after consulting the doctor. Self-adjustment of medication should not be done."
"Dehydration is treated with fluids and minerals (electrolytes). Mild dehydration without nausea and vomiting can be treated with oral fluids and electrolytes. Moderate to severe dehydration usually is treated in the hospital or emergency room with intravenous fluids and electrolytes.
Blood loss can be treated with intravenous fluids and blood transfusions. Continuous and severe bleeding needs to be treated immediately.
Septic shock is an emergency and is treated with intravenous fluids and antibiotics.
Postural hypotension can be treated by increasing water and salt intake, using compression stockings to compress the leg veins and reduce the pooling of blood in the leg veins, and in some patients, the use of a medication called midodrine (ProAmatine). The problem with ProAmatine is that while it increases blood pressure in the upright position, the supine blood pressure may become too high, thus increasing the risk of strokes. Mayo clinic researchers found that a medication used to treat muscle weakness in Myasthenia gravis called pyridostigmine (Mestinon) increases upright blood pressure but not supine blood pressure. Mestinon is an anticholinesterase medication that works on the autonomic nervous system, especially when a person is standing up. Side effects of pyridostigmine include minor abdominal cramping or increased frequency of bowel movements. Increasing salt intake can lead to heart failure in patients with existing heart disease and should not be undertaken without consulting a doctor.
Vasovagal Syncope can be treated with several types of drugs such as beta blockers , selective serotonin reuptake inhibitors , fludrocortisone (Florinef) (a drug that prevents dehydration by causing the kidney(s) to retaining water). A pacemaker can also be helpful when a patient fails drug therapy."
So - if you are mostly experiencing this upon exercise I would guess dehydration is the main factor, though I am NOT a doctor and CANNOT diagnose anything.
Try drinking an electrolyte replacement fluid before , during, and after exercise and see if that helps. If you want to make your own sports drink look on running sites, they often have recipes for fluid replacement drinks that you can make yourself, or you could try pedialyte or gatorade.
Good luck.
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Argue for your limitations, and sure enough, they\'re yours.
Richard Bach
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