Blood pressure depends on the force with which the heart pumps blood into the arteries and on the resistances that oppose its free flow. It therefore corresponds to the pressure exerted in the arteries during its two phases of work: contraction of the left ventricle of the heart (systolic or "maximum" pressure) and its relaxation (diastolic or "minimum" pressure).
Arterial pressure is measured through two values: the maximum (systolic), which corresponds to pressure values at rest equal to or less than 120 millimeters of mercury (mmHg), and the minimum (diastolic), equal to or less than 80 millimeters of mercury (mmHg).
Hypotension means blood pressure values lower than those considered normal: maximum (systolic) resting pressure lower than 90 millimeters of mercury (mmHg) and / or minimum (diastolic) pressure lower than 60 mmHg.
In healthy people, hypotension does not cause any symptoms and only rarely can it cause dizziness or fainting or, in more serious cases, due to identifiable causes, can it be life threatening. Clinically, it is a less serious condition than high blood pressure (hypertension).Symptoms
Hypotension, especially when onset suddenly, can occur with:
- dizziness or lightheadedness
- fainting (syncope)
- blurred vision
- lack of concentration
If disturbances of this nature appear, the attending physician should be informed as they could be signs of more important pathologies.
Hypotension, however, may present with signs of a more serious condition, potentially life-threatening due to insufficient blood supply to the organs, which include:
- mental confusion, especially in older people
- cold, clammy, pale skin
- shallow and frequent breathing
- rapid and weak pulse
If symptoms similar to those listed above appear, you should immediately call a doctor or seek help from a healthcare professional or an emergency room.
If, on the other hand, low blood pressure does not cause any problems, the treating doctor will decide whether to prescribe (routine) check-ups.Causes
Blood pressure depends on the force with which the heart pumps blood into the arteries and on the resistances that oppose its free flow. It therefore corresponds to the pressure exerted in the arteries during the two phases of cardiac activity: contraction of the left ventricle of the heart (systolic or "maximum" pressure) and its relaxation (diastolic or "minimum" pressure).
The guidelines indicate that the optimal blood pressure is less than 120/80 millimeters of mercury (mmHg).
The blood pressure value varies continuously: some conditions such as body position, breathing rhythm, stress, general physical condition, medications, type of diet and time of day can affect the blood pressure value . The pressure, in fact, is usually lower at night and rises abruptly when you wake up.
Some people develop hypotension in old age.
Lowering of blood pressure
The blood pressure value varies from person to person. The blood pressure level is considered too low only if it causes the appearance of disturbances.
The possibility of experiencing disorders related to constitutional hypotension is more frequent in the summer months, since the high temperature can accentuate or favor it.
A sudden drop in blood pressure can be dangerous. A change of just 20 mmHg can cause dizziness and fainting because the brain is not receiving an adequate blood supply. Major drops in blood pressure, such as those due to uncontrolled bleeding, severe infections, or allergic reactions, can be life-threatening.
Conditions that cause hypotension
Some conditions can determine the onset of hypotension, they include:
- pregnancy, as the cardiovascular system rapidly undergoes dimensional changes
- heart ailments, such as slow heart rate (bradycardia), heart valve problems, heart attack and cardiac arrest
- endocrine problems, such as thyroid disease and parathyroid disease, adrenal insufficiency (Addison's disease), low blood sugar (hypoglycemia) and, in some cases, diabetes
- dehydration, or when the body loses more fluids than it takes in: fever, vomiting, acute diarrhea, excessive use of diuretics and excess physical activity may be the cause
- loss of blood, as can happen following a serious injury or internal bleeding
- severe infection (septicemia)
- severe allergic reaction (anaphylaxis), during which hypotension may be accompanied by breathing problems, hives, itching, swelling in the throat
- deficiency of vitamin B-12 and folic acid in the diet
Some medications can cause arterial hypotension:
- diuretics, such as furosemide and hydrochlorothiazide
- alphablockers, such as prazosin
- beta blockers, such as atelonol and propranolol
- Parkinson's disease medications, such as pramipexole, or those containing levodopa
- some antidepressants (tricyclic antidepressants) which contain doxepin and imipramine
- erectile dysfunction medications, which contain sildenafil or tadalafil, especially when also taking nitroglycerin, a medicine used for the heart
Types of hypotension
Hypotension can be distinguished on the basis of the causes that cause it into:
- orthostatic hypotension, or the sudden drop in blood pressure that occurs following the transition from a sitting or lying to standing position that can occur for various reasons, including dehydration, a prolonged period of time spent in bed or sitting with legs crossed or in squatting position, pregnancy, diabetes, heart problems, excessive heat, presence of extensive varicose veins and some neurological disorders; this occurs mainly in adults over the age of 65
- postprandial hypotension, or the sudden drop in blood pressure after eating, common in the elderly, especially in those who suffer from hypertension or autonomic nervous system disorders such as Parkinson's disease
- neurological mediated hypotension, occurs in children and young people after a long period of standing
- multiple system atrophy with orthostatic hypotension, or Shy-Drager syndrome, is a rare disease that causes progressive damage to the autonomic nervous system
Blood pressure can be measured:
- in the pharmacy
- to the family doctor, or by a healthcare professional (nurse)
- at home, using the mercury sphygmomanometer or an automatic meter
Between 40 and 74 years of age, blood pressure should be measured at least once every 5 years. If you suffer from low blood pressure and have ailments, it is advisable to visit the family doctor who may request some laboratory and instrumental tests:
- blood tests, to check the level of blood sugar (possible diabetes), cortisol (possible Addison's disease), the number of red blood cells (possible anemia)
- urinalysis, to search for any infections
- electrocardiogram, echocardiogram and stress test, for the assessment (diagnosis) of any heart problems
- pressure holter, or the measurement of blood pressure for 24 hours through a portable device that detects it every 30 minutes to identify the cause during the day
- radiological examinations, such as a CT scan or chest X-ray, to check for changes in the heart or lungs
- passive orthostatic stimulation test, to assess whether hypotension depends on alterations in the functioning of the nervous system
If hypotension does not cause disturbances (symptoms), no treatment is required, while if it causes disturbances and depends on a specific factor, it is necessary to treat the determining cause. For example, your family doctor might suggest that you:
- change the medications you take or adjust the doses, if they are the cause of hypotension
- wear compression stockings, to improve blood circulation
Medicines to raise blood pressure are rarely needed because lifestyle measures are usually effective.Prevention
To alleviate the disorders caused by hypotension it is advisable:
- get up slowly, when changing from lying to standing position
- raise the headboard of the bed at least 15 centimeters, using two pillows or heavy books
- eat light and frequent meals and lie down or sit down for some time after the meal is over
- drink more water
It is to be avoided:
- bending over or changing body position suddenly
- sitting or standing for a long time
- drinking caffeinated beverages, especially in the evening and before bedtime
- drinking too much alcohol
Mild forms of arterial hypotension can cause dizziness, weakness, fainting, and a risk of injury and trauma from falls. Severe forms can deprive the body of the oxygen it needs to perform its normal functions, causing damage to the heart and brain. A state of shock can also occur, characterized by paleness, cold sweats, fast and shallow breathing, and a weak and rapid pulse.Shock, in the absence of timely and adequate treatment, can even lead to death.In-depth link
Mayo Clinic. Low blood pressure (hypotension) (English)
NHS. Low blood pressure (hypotension) (English)