What is low blood pressure?
Just a few decades ago, doctors thought a blood pressure reading of 160/95 millimeters of mercury (mm/Hg) was an acceptable target rate for most people. Today, those numbers are regarded as dangerously high. These days blood pressure lower than 120/80 is optimal for good health. The ongoing downward revision of blood pressure standards has led some people to assume that just as you cannot be too thin or too rich, your blood pressure cannot be too low. However, that is not always the case. Low blood pressure brings some health problems as well. Many people who have low blood pressure (hypotension) are healthy and have no related signs or symptoms. However, others experience dizziness and fainting, or indicate serious heart, endocrine or neurological disorders. Severely low blood pressure can deprive the brain and other vital organs of oxygen and nutrients. This situation leads to shock, which is a life-threatening condition.
Signs and symptoms of low blood pressure
Some people with low blood pressure are in peak physical condition, with strong cardiovascular systems and a reduced risk of a modern man’s common problems such as heart attack and stroke. For these people, low blood pressure is a cause for celebration rather than concern. However, low blood pressure can also signal an underlying problem. This happens especially when it drops suddenly or goes accompanied by signs and symptoms such as dizziness or lightheadedness, fainting, lack of concentration, blurred vision, or nausea. When a person has cold, clammy, pale skin, rapid, shallow breathing, fatigue, depression and thirst, low blood pressure is a condition that requires treatment.
Causes of low blood pressure
The heart is the prime mover of the circulatory system, with each beat launching blood on a journey through 60,000 miles of arteries, veins and capillaries, ultimately circulating about 2,000 gallons of blood each day. To do this, it contracts an average of 70 times a minute with the same amount of force you would use to squeeze a tennis ball. Blood pressure is a measurement of the pressure in your arteries during the active and resting phases of each heartbeat, which is why we have two different numbers in blood pressure readings. It is important to know what these numbers mean.
- Systolic pressure is the first number in a blood pressure reading. Heart generates this pressure when it is pumping blood through arteries to the rest of your body.
- Diastolic pressure is the second number in a blood pressure reading. This refers to the amount of pressure in your arteries when your heart is at rest between two beats.
Although you can get an accurate blood pressure reading at any given time, blood pressure is not a static number. In fact, it can vary considerably in a short amount of time, even from one heartbeat to the next depending on your body position, breathing rhythm, stress level, physical condition, the medications you take, what you eat and drink, and even the time of day. Blood pressure is usually lowest at night and rises sharply at waking time. Current guidelines identify normal blood pressure as lower than 120/80, while many experts think 115/75 is optimal. Higher readings indicate increasingly serious risks of cardiovascular disease or stroke.
Blood pressures formerly considered healthy were 120 to 139 systolic and 80 to 89 diastolic. However, today doctors believe these readings increase the risks of stroke and cardio. Low blood pressure, on the other hand, is much harder for doctors to quantify. Some experts define low blood pressure as readings lower than 90 systolic or 60 diastolic. If you have it, you need have only one number in the low range for your blood pressure to be considered lower than normal. In other words, if your systolic pressure is a perfect 115, but your diastolic pressure is 50, you have lower than normal blood pressure. Yet this can be misleading because what constitutes low blood pressure is relative, varying considerably from one person to another. For that reason, doctors often consider chronically low blood pressure too low only if it causes noticeable signs and symptoms typical for this problem. On the other hand, a sudden fall in blood pressure can be dangerous for everyone. A change of just 20 mm/Hg, or a drop from 130 systolic to 110 systolic, can cause dizziness and fainting when the brain fails to receive an adequate supply of blood. By the way, this is one of the most important roles of the blood - supplying brain and all other pars of the body with oxygen and nutrition.
Low blood pressure can be a boon when it results from a healthy lifestyle of individual. Athletes and people who exercise regularly tend to have a lower blood pressure than do people who are not as fit. The same applies to nonsmokers and people who eat well and maintain a normal weight. However, in some instances, low blood pressure can be a sign of serious, even life-threatening disorders.
Although the reason for lower than normal blood pressure is not always clear, doctors know there are some factors that can cause or contribute to low and sometimes dangerously low readings of blood pressure. These are pregnancy, certain medications, heart problems, dehydration, blood loss, severe infection allergic reaction and postural hypotension. Nutritional deficiencies, such as a lack of the essential vitamins B-12 and folic acid can cause anemia, which in turn can lead to low blood pressure as well.
Low blood pressure risks
Even moderate postural, postprandial or neutrally mediated hypotension can seriously affect one’s quality of life. It could lead not only to dizziness and weakness but also to fainting and a risk of injury from falling. Moreover, severely low blood pressure from any cause can deprive a body of enough oxygen to carry out its normal functions, leading to damage to the heart and brain. Chronic low blood pressure may increase the risk of Alzheimer's-type dementia in some older adults. Diastolic pressures lower than 70 over a long period are most closely associated with dementia. For every 10-point drop in pressure, the likelihood of dementia may increase by as much as 20 percent. For years, researchers debated whether the low blood pressure often seen in people with Alzheimer's was a consequence or a cause of the disease these people have. Current research seems to indicate that it is both. In younger people, however, lower blood pressure is usually associated with a reduced risk of dementia. Scientists speculate that age-related changes in cardiovascular function may explain the difference they were seeking. Because older adults are more likely to have blocked arteries than younger people are, their blood pressure may need to be higher to maintain adequate blood flow to the brain.
Low blood pressure treatment
Low blood pressure without signs or symptoms rarely requires treatment. In symptomatic cases, the appropriate therapy depends on the underlying cause. In this case, a doctor usually tries to address the primary health problem of dehydration, heart failure, diabetes or hypothyroidism, rather than low blood pressure itself.
When hypotension is drug-induced, treatment usually involves changing the dosage of the medication or stopping it entirely. If it is not clear what is causing hypotension, or if no effective treatment exists, the goal is simply to raise the blood pressure and relieve the signs and symptoms. Depending on the patient’s age, health status, and type of hypotension, a doctor has few choices for treatment. He might decide to increase salt intake as the first treatment option. Experts usually recommend limiting the amount of salt in your diet because sodium can raise blood pressure. However, for people with low blood pressure, raising it can be a good thing. Still, it has not quite as simple as dousing your salads with one of the new designer salts. Because excess sodium can lead to heart failure, especially in older adults, it is important to check with your doctor before upping your salt intake.
Increased water might also help, especially when we know that nearly everyone can benefit from drinking more water. This is especially true of people with low blood pressure, because fluids increase blood volume and help prevent dehydration, both of which are important in treating hypotension.
Compression stockings are the same elastic stockings and leotards commonly used to relieve the pain, swelling, and blood stagnation of varicose veins. This may help reduce the pooling of blood in the legs. The medicine midodrine is a common choice of many doctors to raise standing blood pressure levels in people with orthostatic hypotension. However, many of those people have high blood pressure when sitting or lying down and at night, when blood pressure typically declines. In addition to increasing standing blood pressure, midodrine also raises already-high supine pressure, leading to the possibility of strokes, so now it appears that another drug, pyridostigmine, increases standing blood pressure without affecting supine pressure.