Low blood pressure, medically termed hypotension, is defined as a blood pressure less than 90/60 mm/Hg.
What is low blood pressure?
Low blood pressure or hypotension is a condition in which the pressure of blood circulating throughout the body is less than normal or lower than expected, given the environmental conditions.
Most people with hypotension are asymptomatic. It may not always cause symptoms, but if it does, medical attention may be required. It can occur as a standalone condition or as a symptom of various other diseases.
Low blood pressure is primarily a problem if it causes harm to the body. For instance, if a person’s blood pressure is too low, vital organs like the brain may be deprived of oxygen and nutrients.
Types of low blood pressure
Low blood pressure is classified into three types—orthostatic hypotension, postprandial hypotension and neurally mediated hypotension. Each is set off by different causes, such as a change in body position, consuming a meal or an abnormal reflex.
Orthostatic hypotension
Orthostatic hypotension is low blood pressure caused by a change in the body’s position. This most commonly occurs when a person stands up after lying down. It often lasts only a few seconds or minutes.
The drop in systolic pressure will be 20 mm/Hg or greater, and the decrease in diastolic pressure will be 10 mm/Hg or greater. This is also termed as postural hypotension since it occurs due to changes in posture.
Gravity gives rise to hypotension because blood pools in the legs. The heart would usually compensate by pumping more blood to the brain. However, when orthostatic hypotension occurs, that mechanism fails. The brain tends to receive less oxygen from the bloodstream, and a person may feel lightheaded or dizzy. In some cases, the individual may faint.
It primarily affects the elderly, people with high blood pressure and Parkinson’s disease. However, one may experience it during pregnancy, dehydration, high temperature or Diabetes, heart problems or certain nerve disorders.
Postprandial hypotension
Postprandial hypotension is a drop in blood pressure that occurs shortly after eating.
Typically, the heart rate increases after a meal to circulate blood to the digestive system. This process doesn’t occur for a person with postprandial hypotension, resulting in dizziness and fainting.
It can also bring about tripping and falling in such people, potentially injuring them.
Small, frequent and low-carbohydrate meals can sometimes help alleviate symptoms.
Neurally mediated hypotension
Prolonged standing gives rise to neurally mediated hypotension, also referred to as vasovagal syncope or reflex syncope.
Symptoms may also manifest after exposure to warm environments, such as a hot shower or hot summer weather.
As already pointed out, gravity allows blood to pool in the legs when blood pressure is low. The heart needs to beat faster to supply enough blood to the brain, but a malfunction causes the brain to signal the heart to beat slower, reducing blood supply to the brain.
Types of blood pressure measurements
A blood pressure test measures the arterial pressure as the heart pumps blood. Blood pressure is calculated using two numbers —Systolic and Diastolic pressure.
Systolic pressure
Systolic blood pressure is the first and highest number that measures the pressure inside the arteries when the heart beats.
Diastolic pressure
Diastolic blood pressure is the second and lower number that measures the pressure inside the artery when the heart is at rest between beats.
Causes of low blood pressure
Pregnancy
Blood pressure typically drops during the first 24 weeks of pregnancy, making a pregnant woman prone to low blood pressure.
Medications
Several medications bring about low blood pressure, including diuretics, hypertension medications, beta-blockers, medicines for Parkinson’s disease, erectile dysfunction, antidepressants, narcotics and alcohol.
When combined with high blood pressure medications, other prescription and over-the-counter drugs may cause low blood pressure.
Endocrine problems
Complications with hormone-producing glands present in the endocrine system of the body, like hypothyroidism, Addison’s disease, hypoglycaemia and hyperglycaemia, are known to result in low blood pressure occasionally.
Heart problems
An abnormally low heart rate or bradycardia, heart valve problems, heart attack and heart failure, are heart conditions that can cause low blood pressure. These conditions may make the heart incapable of circulating enough blood to meet the body’s requirements.
Nutritional deficiencies
Anaemia brought on by a lack of essential vitamins B-12 and folic acid can predispose to low blood pressure.
Low blood volume
Blood loss from a severe injury or surgery can result in low blood pressure. Low blood volume can be exacerbated by dehydration.
Alcohol
Alcohol consumption influences the renin-angiotensin-aldosterone system (RAAS).
The kidneys control the RAAS, which regulates blood pressure via three hormones —renin, angiotensin and aldosterone.
Alcohol raises renin levels in the blood, which causes blood vessels to constrict, decreasing blood volume and causing low blood pressure.
Symptoms of low blood pressure
People with low blood pressure show the following symptoms.
Weakness
Due to dehydration, low blood pressure decreases blood volume and causes total weakness, where a person lacks energy. Vitamin B-12 deficiency anaemia also brings on hypotension and weakness in an individual.
Fainting
American Heart Association states that a sudden dip in the blood pressure makes the heart supply insufficient blood to the brain. The decreased blood flow to the powerhouse of the body, the brain, makes a person faint.
Dizziness
The reduced oxygenated blood flow to the brain initially causes blurry vision and brings about dizziness.
Tiredness
Major organs of the body fail to receive enough blood to function properly, making a person feel tired and unwell.
Nausea
Nausea occurs as a result of orthostatic hypotension, which happens due to prolonged standing. The heart and brain miscommunication is the trigger for this symptom.
Dehydration
Most often, low blood pressure occurs due to dehydration which causes low blood volume. Therefore, dehydration frequently occurs in people with hypotension.
Diagnosing low blood pressure
A sphygmomanometer is primarily used for knowing the blood pressure of an individual and diagnosing hypotension.
Lab testing
Blood tests can assist in the diagnosis of low blood sugar or hypoglycaemia, high blood sugar or hyperglycaemia or anaemia, all of which are causes of low blood pressure. Treating the cause helps solve the issue.
Imaging
Electrocardiogram (ECG) measures the heart’s electrical activity and aids in the identification of potential problems affecting blood and oxygen supply to the heart.
An echocardiogram determines the size, shape and function of the heart. X-ray and MRI scans are also a part of the imaging tests.
Tilt table test
A tilt table test can assess the body’s reactions to position changes. The test entails lying on a table tilted to raise the upper part of the body, simulating the transition from a horizontal to a standing position.
The body is held in place by straps. During the test, the heart rate and blood pressure are monitored.
Treatments for low blood pressure
The following treatments would be the recommendation by a general practitioner for low blood pressure.
Changing medication
Changing or adjusting the medication or dosage can help control low blood pressure. Without a medical practitioner’s consultation, one should never change the medication’s dosage.
Increasing blood volume
An NCBI book titled ‘Physiology, Blood Volume’ states that the rising or falling of arterial pressure reflects the changes in the blood volume.
Blood volume reduction results in collapsed vessels, lower pressure and lower perfusion pressure.
The cardiovascular system compensates for low blood volume by constricting blood vessels until the body achieves a blood pressure that restores proper perfusion pressure.
Making blood vessels constrict
Veins play a role in blood pressure regulation, though their effect is much less than that of arterioles.
Veins dilate and constrict to alter the amount of blood they can hold. Constricting veins reduce their capacity to hold blood, allowing more blood to return to the heart and be pumped into the arteries. Blood pressure rises as a result.
Lifestyle changes
Fluids
Fluids help prevent dehydration and increase blood volume, which is essential in treating hypotension.
Salt
Increasing the salt intake is a needed treatment for high blood pressure. Salt contains sodium, and increased sodium intake may raise the blood pressure of people with hypotension.
Small, frequent meals
Smaller and more frequent meals have been shown to help with hypotension.
Compared to larger and heavier meals, smaller and more frequent meals reduce the gap between meals and keep a person full, reducing the chances of low blood pressure.
Complications of low blood pressure
Fall-related injury
Falls due to low blood pressure can occur at any age, though they are more prevalent in the elderly.
Bathroom falls due to hypotension are a common occurrence.
Since hypotension can cause dizziness and fainting, these are the most dangerous symptoms. Falls can result in broken bones, concussions and other severe or fatal injuries.
Preventing falls should be the top concern for a person with hypotension.
Shock
With the drop in blood pressure, the vital organs are deprived of oxygen and essential nutrients. When this occurs, low blood pressure can result in shock, necessitating immediate medical attention.
Cold and sweaty skin, a blue skin tone, rapid breathing or a weak and rapid pulse are signs of shock.
Heart problems
Low blood pressure forces the heart to try to make up by pumping faster or harder. This can terminate in permanent heart damage and even heart failure over time.
Heart problems can give rise to issues such as deep vein thrombosis and stroke, as blood does not flow normally, resulting in clot formation.
When to see a doctor?
Most symptoms of low blood pressure are transient. However, if the symptoms persist for an extended time, it is critical to consult a doctor to understand the severity of the condition and get a treatment plan.
If a person has low blood pressure along with other concerning symptoms, such as mental confusion, loss of consciousness and a weak, rapid pulse and breathing pattern, immediate medical attention is mandatory.
Conclusion
Hypotension is a condition with no initial symptoms in many people. For others, it can cause unpleasant and disruptive symptoms to their daily lives and activities.
If low blood pressure is suspected, it is critical to get it diagnosed and treated as soon as possible to avoid falls and other complications.
Fortunately, this condition is frequently treatable, and a healthcare provider can explain many things to assist a person in caring for themselves.
FAQs
