Hypotension

Overview of hypotension

Blood pressure is an important parameter that determines the overall health of an individual. Idiopathic as well as identifiable fluctuations of blood pressure can affect health and lifestyle. A common condition of abnormal blood pressure in the human body is “hypotension”, more commonly known as low blood pressure. As the name implies, it is a condition of reduced blood pressure, which after a certain limit may lead to extreme consequences. The condition is common in people of all age groups and genders.

In the recent past, there has been an alarming rise in emergency hospitalization due to low blood pressure. This has worried doctors and the health organizations in different countries.

What is hypotension?

Hypotension or “Low blood pressure” is a condition of abnormally dropped blood pressure particularly in the arteries of the circulatory system. In proper medical terms, blood pressure is the collective pressure exerted by the circulating blood on all the blood vessels (arteries). Two types of blood pressure are there namely- Systolic and Diastolic pressure. The normal values of systolic and diastolic pressure are- 120 mm Hg and 80 mm Hg. A dip in the systolic pressure below 90 mm Hg and the diastolic pressure below 60 mm Hg is medically termed as low blood pressure. This variation differs according to the age of the individual. Numerous environmental, psychological physiological and dietary factors contribute to low blood pressure in an individual.

What are the main causes of hypotension?

Hypotension may result from a range of aetiological factors. These are listed below-

• Low blood volume (Hypovolemia)
• Dilated blood vessels
• Hormonal variations (during menstruation or pregnancy)
• Side-effects of certain broad-spectrum drugs (alpha and beta channel blockers)
• Low hemoglobin (anemia)
• Cardiovascular disorders
• Endocrinal problems
• Dehydration due to diarrhea and vomiting
• Low intake of fluid on a daily basis
• Hemorrhage
• Reduced cardiac output

What are the common signs and symptoms?

Hypotension typically presents as-

• Breathlessness
• Chest pain, tightness, and discomfort
• Arrhythmia
• Low-grade fever
• Stiffness of neck
• Headache and dizziness
• General malaise
• Upper back pain
• Cough with phlegm
• Persistent diarrhoea and vomiting
• Indigestion (Dyspepsia)
• Painful urination (Dysuria)
• Allergic reactions of serious nature
• Seizures, fits and convulsions
• Loss of consciousness
• Blurred vision (temporary)
• Fatigue
• Connective tissue disorders
• Black discolouration of stools

Postural (orthostatic) hypotension

In this condition, an abrupt drop in the blood pressure occurs within 3 minutes of standing. This happens because the cardiovascular system fails to regulate the flow of blood to the lower extremities when they are in a vertical position. This condition is often characterized by syncopal episodes.

The main causes of Orthostatic hypotension are as follows-

Cardiovascular factors

• Arrhythmia
• Aortic stenosis
• Myocardial infarction
• Pericarditis
• Dilated cardiomyopathy
• Advanced heart failure

Endocrinal factors

• Diabetes
• Post-gastrectomy dumping syndrome
• Primary hypoaldosteronism
• Phaeochromocytoma

Neurological factors

• Vasospasm and vasovagal faints
• Alcoholic neuropathy
• Tabes dorsalis
• Parkinson’s disease
• Spinal cord lesions
• Syringomyelia
• Alcoholic neuropathy
• Sympathectomy

Other causes

• Pernicious anaemia (due to Vitamin B12 deficiency)
• Varicose veins
• Pregnancy
• Being bed-ridden for a long time 

The main symptoms of Postural hypotension are 

• Light-headedness
• Feeling of fainting, falling or loss of balance
• Blurred or tunnel vision
• Throbbing headaches
• Mental confusion
• Feeling of an unexplained pressure on the shoulders and neck
• Feeling hot and clammy
• Sudden feeling of nausea
• Weakness
• Fatigue

Acute hypotension

Acute hypotension presents as certain serious complications that may lead to cerebral, renal and myocardial damage due to an extreme shortage of oxygen. It manifests as any of the following types of shocks-

• Septic shock
• Cardiogenic shock
• Hypovolemic shock
• Anaphylactic shock
• Neurogenic shock

Some of the general causes of acute hypotension are as follows-

• Vasodilation: Heat exposure, anti-hypertensive drugs
• Broad-spectrum drugs: Anxiolytics, antidepressants, alcohol, narcotic analgesics
• Cardiac problems: Aortic regurgitation, tamponade, myocardial infarction, arrhythmia
• Autonomic nervous system failure
• Pulmonary embolism
• Micturition syncope

Chronic hypotension

It is usually seen in people having Addison’s disease, which is a kind of autoimmune adrenal failure. This is primarily marked by a drop in the systolic BP below 110 mm Hg.

Vasovagal faints

In this condition, pooling of venous blood occurs with a significant drop in the return of venous blood to the heart. The patient may experience sweating and pre-syncope before collapsing. A transient loss of consciousness occurs due to reduced cerebral perfusion.

Postprandial hypotension

This is seen in 40-80% of people who have autonomic dysfunction. The systolic arterial pressure drops below 90 mm Hg in this condition.

Diagnosis

The doctors recommend the following laboratory examinations to correctly detect the disease-

• Blood pressure measurement (by sphygmomanometer or arterial catheter)
• Measurement of mean arterial pressure
• Tilt table test (for evaluating vasovagal syncope)
• Full blood count
• Fasting glucose
• Pregnancy test
• Electrocardiogram
• Echocardiogram
• Platelet count
• Coagulation profile
• Liver function test

Treatment & Prevention

The only way to treat hypotension is through medications and lifestyle and dietary changes. The most commonly prescribed drug is fludrocortisone that aims at treating orthostatic hypotension (low BP symptom of dizziness that appears on standing up too fast). Patients with chronic orthostatic hypotension are prescribed Midodrine.

Prevention of hypotension includes:

• Drinking more water and replenishing the lost electrolytes.
• The patient may be asked to slightly increase sodium intake through diet.
• Wear compression stockings that are used to treat varicose veins.
• Eat low carb foods and avoid eating heavy meals at one sitting.

References