Low blood pressure, or hypotension, is not often considered to be a major problem.
However, severe hypotension can indicate an underlying problem, and it can lead to serious heart disorders and organ failure, because oxygen and nutrients may not reach key organs.
The heart is a muscle that pumps blood around the body continuously. Blood that is low in oxygen is pumped towards the lungs, where it picks up oxygen.
The blood pressure cuff must be the right size.
The heart pumps this oxygen-rich blood around the body to supply our muscles and cells. The pumping of blood generates blood pressure.
Measures of blood pressure include two different types of pressure: Systolic pressure is the blood pressure when the heart contracts. It is measured at the moment of maximum force of the contraction, when the left ventricle of the heart contracts.
Diastolic pressure is the blood pressure measured between heartbeats, when the heart is resting and opening up, or dilating.
A blood pressure reading measures both the systolic and diastolic pressures. The figures usually appear with a larger number first, which is the systolic pressure, and then a smaller number, the diastolic pressure.
If a person’s blood pressure is 120 over 80, or 120/80 mmHg, the systolic pressure is 120mmHg, and the diastolic pressure is 80mmHg. The abbreviation mmHfg means millimeters of mercury.
Levels of blood pressure can fluctuate by up to 30 or 40 mmHg during the day. Blood pressure is lowest while sleeping or resting. Physical activity, high levels of stress and anxiety causes blood pressure to rise. Blood pressure must be taken under similar circumstances each time, so that when the readings are compared, they refer to the same state of physical activity.
An adult with a reading of 90/60 mmHg or lower can be regarded as having hypotension, or low blood pressure.
Symptoms
Many people with low blood pressure have no symptoms. People who are very fit may have low blood pressure and be in good health. In others, a chronic problem such as a hormone imbalance, or acute condition, such as anaphylaxis, can trigger hypotension.
Dizziness is a common symptom of low blood pressure.
Common symptoms include: Blurred vision, cold, clammy, pale skin, depression, dizziness, fainting, and nausea, fatigue and weakness, palpitations, rapid, shallow breathing and thirst.
If the hypotension is not severe and there are no underlying conditions, no treatment is necessary.
If it is severely low, or significantly lower than usual, blood and oxygen supply to the brain and other vital organs may be insufficient. In this case, the patient will need medical attention. Severe hypotension indicates an underlying problem.
Causes
Blood pressure can become low for a number of reasons.
Heart disease
Bradycardia, or low heart rate, heart valve problems, heart attack and heart failure can cause very low blood pressure, mainly because the heart cannot pump enough blood to keep the pressure up.
Orthostatic, or postural hypotension
A change in posture, such as standing up from a sitting or lying position, can lead to a drop in blood pressure, but this returns quickly to normal levels. This is more common as people get older. People with diabetes can experience this if they have damage to their autonomic nervous system.
Low blood pressure after meals
Sometimes, blood pressure falls after eating, causing light-headedness, dizziness, and faintness. It is more common among older people, especially those with high blood pressure, diabetes, or Parkinson’s disease.
After eating, the intestines need more blood supply for digestion. The heart beats faster, and blood vessels in other parts of the body narrow to help maintain blood pressure. With age, this process becomes less effective.
To minimize the problem, it may help to lie down after eating, reduce carbohydrate intake, and eat smaller meals, more frequently.
Using the bathroom, swallowing, and coughing
Blood pressure can drop when using the bathroom. Straining while urinating or having a bowel movement stimulates the vagus nerve, and this raises acetylcholine levels in the body.
Swallowing and coughing can also lead to faintness due to the stimulation of the vagus nerve.
