How is Blood Pressure calculated?
This short article will explain how to read blood pressure terminology, to assist in understanding low blood pressure numbers. When the heart beats it consists of a contraction which forces blood into the arteries, that subsequently causes the pressure to increase. At this stage, the arterial pressure is greatest. This is known as the systolic pressure. It is followed by a relaxation of the heart muscle, which then refills with blood from the veins, and causes the pressure on the arteries to decrease. This is known as the diastolic pressure. Both the systolic and diastolic pressures are measured in terms of millimetres of mercury (mmHg). The standard notation for blood pressure reading is systolic first, followed by diastolic.
Normal Blood Pressure
The normal blood pressure range for healthy young adults is betwwen 110/70 mmHg and 120/80. However, the term ‘low blood pressure’ or ‘very low blood pressure’ is relative, and depending on the individual, blood pressure lower than 110/70 mm Hg may produce no symptoms compared to the ‘good blood pressure’ range.
Usually lower blood pressure is more beneficial for long term health.
Daily variation in blood pressure
Throughout the day, blood pressure varies, depending on activity levels. Sometimes this can be by as much as 30-40 mmHg (both systolic and diastolic). Blood pressure is generally lowest during sleep or periods of relaxation. During exercise, or periods of stress or anxiety, blood pressure increases. Therefore, when keeping blood pressure charts, or other extended blood pressure monitoring, measurements should be performed under similar conditions at the same time each day to ensure accurate results.
What is very low blood pressure?
Very Low blood pressure is also known as hypotension. People with a reading of 90/60, or less, are commonly regarded as having very low blood pressure. Because blood pressure varies during the day, there may be a range of low blood pressure readings.
Is very low blood pressure dangerous?
Low blood pressure readings may indicate a dangerous condition when they drop suddenly, or are accompanied by symptoms such as dizziness or fainting. Severely low blood pressure can indicate serious heart, endocrine system, or neurological problems, and can deprive the brain and other vital organs of oxygen and nutrients.
This in turn can lead to shock, which can be a life-threatening condition. Dangerous low blood pressure should always be investigated and treated.
Causes of low blood pressure
The are many possible reasons for low blood pressure, many of which are listed below:
Pregnancy – During the first 24 weeks of pregnancy, it is normal for blood pressure to drop.
Medications – A number of drugs can cause low blood pressure, including diuretics and other drugs that treat hypertension; heart medications such as beta blockers; drugs for Parkinson’s disease; tricyclic antidepressants; Viagra, particularly in combination with nitroglycerine; narcotics and alcohol. Other prescription and over-the-counter medications may cause low blood pressure when taken in combination with high blood pressure drugs.
Heart problems – Among the heart conditions that can lead to low blood pressure are an abnormally low heart rate (bradycardia), problems with heart valves, heart attack and heart failure. These are conditions in which your heart may not be able to circulate enough blood to meet your body’s needs.
Endocrine problems – these include an underactive or overactive thyroid (hypothyroidism and hyperthyroidism respectively), adrenal insufficiency (Addison’s disease), low blood sugar and, in some cases, diabetes.
Dehydration – Fever, vomiting, severe diarrhea, overuse of diuretics and strenuous exercise can all lead to dehydration, a potentially serious condition in which your body loses more water than you take in. Even mild dehydration, a loss of as little as 1 percent to 2 percent of body weight, can cause weakness, dizziness and fatigue.
Blood loss – A significant loss of blood from major trauma or severe internal bleeding reduces blood volume, leading to a severe drop in blood pressure.
Severe infection (septic shock) – Septic shock can occur when bacteria leave the original site of an infection, most often in the lungs, abdomen or urinary trac, and enter the bloodstream. The bacteria then produce toxins that affect the blood vessels, leading to a profound and life-threatening decline in blood pressure.
Allergic reaction (anaphylaxis) – Anaphylactic shock can be a fatal allergic reaction that can occur in people who are highly sensitive to drugs such as penicillin, or to certain foods such as peanuts, or to bee or wasp stings. This type of shock is characterized by breathing problems, hives, itching, a swollen throat and a sudden, dramatic fall in blood pressure.
Nutritional deficiencies – A lack of the essential vitamins B-12 and folic acid can cause anemia, which in turn can lead to low blood pressure.
Symptoms of low blood pressure
There a number of symptoms whiuch are indicative of low blood pressure, some or more of which may apply to any particular individual:
* Dizziness or lightheadedness
* Fainting (also known as syncope)
* Lack of concentration
* Blurred vision
* Cold, clammy, pale skin
* Rapid, shallow breathing
* Unusual thirst
Diagnosis of Low Blood Pressure
Low blood pressure should be diagnosed by a doctor. The doctor can examine a patient’s medical history, age, specific symptoms, and the conditions under which the symptoms occur, and determine whether there is a significant low blood pressure problem.
Some symptoms – e.g. dizziness and lightheadedness when standing up (postural hypotension), may not necessarily be linked to low blood pressure. Because a wide range of conditions can cause the same symptoms as very low blood pressure, it is important to accurately identify the cause of the symptoms so that the correct treatment can be given.
The Doctor may perform additional diagnostic tests such as :
In-depth monitoring and evaluation of blood pressure readings and pulse rate, involving periods of lying down, and then sitting or standing up.
ECG (electrocardiogram) to detect heart rate and rhythm problems
echocardiogram (an ultrasound test to visualize the heart).
Blood tests to look for anemia or problems with blood sugar levels.
Exercise stress test or electrophysiology test (EP test)
Where the problem only occurs infrequently, it may be necesary to perform extended home ECG monitoring to capture the data over a longer period of time.
Treatment for low blood presure
For many people, chronic low blood pressure can be effectively treated. Initially, the doctor may recommend some simple diet and lifestyle changes to alleviate the effects of very low blood pressure, or to increase the blood pressure. These may include some of all of the following tips:
How to prevent some of the symptoms of very low blood pressure:
1. When moving from lying down to standing position, do so slowly, and pause for rest at the sitting position.
2. Elevate the head of your bed at night by 5 to 20 degrees, by placing bricks or blocks under the head of bed.
3. Avoid heavy lifting.
4. Avoid straining while using the toilet.
5. Avoid prolonged exposure to hot water, such as hot showers and spas.
6. Eat smaller, more frequent meals and rest after eating.
7. Use elastic support (compression) stockings as these restrict blood flow to the legs, and help to keeping more blood in the upper body.
How to raise low blood pressure:
1. Eat a diet higher in salt.
2. Drink a minimum of 8 glasses of liquid per day, especially during hot weather. Sports drinks that are high in sodium and potassium are recommended
3. Consume extra salt and drink more fluids during hot weather or during viral illness, such as a cold or influenza.
4. Have a doctor evaluate any precription or general medications to identify any link to low blood pressure.
5. Get regular exercise to promote blood flow.
6. Drink more coffee (although there is conflicting medical evidence as to whether there is any link between coffee and higher blood pressure