What It Is, What Causes And Prevention

If you are going to take your blood pressure and it shows low values, that is, hypotension, know that, respecting certain limits, this is the best result that could be obtained. Unlike so-called high blood pressure, there is no numerical threshold that determines that blood pressure is too low, unless it causes symptoms.

Considered relatively benign, hypotension is poorly recognized because it is usually asymptomatic. It can affect men and women equally, but is more common among thin young females and the elderly.

Physically active and healthy adults may have lower blood pressure levels when compared to sedentary and/or overweight adults, and this is related to better quality of life and survival.

When episodes of low blood pressure are repeated, they can be due to aging, the use of certain medications and diseases such as diabetes. In most cases, simple lifestyle changes — such as improved hydration, in addition to the treatment of illnesses related to them — are enough to remedy the problem, and medications for its control are rare.

Understand what is hypotension

Blood pressure is influenced by the Autonomic Nervous System (ANS) which remains in balance through the Sympathetic Nervous System (responsible for raising blood pressure levels) and the Parasympathetic Nervous System, represented by the vagus nerve, whose function is to reduce blood pressure . Any ANS imbalance (dysautonomia) can lower the pressure.

Thus, doctors define hypotension as a transitory phenomenon whose diagnosis is made not only by a numerical diagnosis, but by the set of symptoms. Although these may appear at other blood pressure values, those below 90/60 mmHg are generally symptomatic. The explanation comes from cardiologist Minna Moreira Dias Romano, a professor at the Faculty of Medicine of Ribeirão Preto.

“It is precisely because of these characteristics that there is no disease called hypotension”, completes the specialist.

Why does it happen?

Hypotension sometimes has no apparent cause (idiopathic). However, the most common source of the problem is reactive, that is, it occurs as a result of some situations, such as those described below:

Remain standing for a long time, indoors and warm (especially among young people)
Acute blood loss (in a hospital setting)
Dehydration (mainly among the elderly)

Less common causes
Use of certain medications (antihypertensives, anxiolytics, antidepressants, diuretics, analgesics)
Severe infection (septic shock)
Severe allergic reaction (anaphylactic shock)
nutritional deficiencies

How to recognize the symptoms

When they manifest, they can vary depending on the level of pressure drop. Check out the most common manifestations:

feeling unwell
Visual blurring or dimming
feeling nauseous
Loss of consciousness (also called syncope, which occurs in more severe cases)

If symptoms appear when standing up or changing position, hypotension is called orthostatic or postural.

Understand the difference between hypotension and hypertension

Hypertension is a disease characterized by multiple causes, including hereditary factors, excessive consumption of salt and alcohol, obesity, smoking, and it also involves the stiffening of blood vessels and atherosclerosis, which can manifest with aging.

Hypotension, on the other hand, is a natural action of the body (physiological), but it can also be a phenomenon related to some illnesses.

Who needs to be on the lookout?

Hypotension can manifest itself in men, women and even children, but episodes are more frequent in these groups:

thin and young women
People with neurological diseases (such as Parkinson’s)

When should I seek professional help?

According to family doctor Rafael Mendonça Rey dos Santos, a professor at PUC-PR, the time to make an appointment is the moment when you observe the repetition and intensity of episodes of low blood pressure, “especially when it manifests itself with a faint or dizziness that has caused or may cause a fall, and they are already starting to disrupt daily life,” he says.

Anyone who already has an underlying disease should act even faster. The suggestion is to seek out the general practitioner or doctor you are already seeing.

How is the diagnosis made?

At the time of the consultation, the doctor will listen to your complaint and ask questions to identify symptoms, possible triggering factors, predisposing diseases and will also review your family history.

In addition, he will perform the physical examination, the most important part of which is measuring your blood pressure. The practice should be done —preferably— by the doctor himself, in the lying, sitting and standing positions.

The postural hypotension test should also be performed, which is done with the patient standing, after he has remained in that posture for a period of 3 minutes.

The professional will compare all the results found to identify cases of postural hypotension (orthostatic), especially among the elderly. For the latter, an important test that can be requested is the Ambulatory Blood Pressure Monitoring (ABPM), which records blood pressure for 24 hours.

When there is suspicion of arrhythmia, the specialist may also request a test called Holter, to monitor the heart rhythm for a period of 24 hours.

Some doctors may also use the so-called tilt test (Tilt test), a procedure performed on a stretcher that can be placed in different positions to reproduce hypotension phenomena.

How is the treatment done?

Cardiologist Brivaldo Markman, head of the Cardiology Service of the Hospital das Clínicas at UFPE, explains that when hypotension is symptomatic, the goal of treatment is to reestablish blood pressure balance.

For most patients, medical guidelines include improving hydration, adequate salt intake (in people who are not hypertensive) and measures such as lying down with your legs elevated or wearing elastic stockings.

“In cases where there was a careful assessment of the patient and a disease was identified, the focus should be on treating it properly. When drug interactions are found, it is necessary to adjust these medications”, adds the doctor.

The use of drugs to control hypotension is rare and more indicated in cases of neurological diseases. Most of the time, the treatment is successful.

Can you prevent it?

Yes. And exercise is a good prevention strategy. Prefer isometric practices that maintain adequate lower limb muscle mass. For simple cases, calf exercises, good hydration and balanced salt intake can be helpful.

To this must be added prevention measures for cardiovascular diseases, such as taking care of weight, rational consumption of alcohol, avoiding smoking and stress control.

Young people who tend to have blood pressure drop should not neglect hydration and nutrition. In addition, they must be positioned in environments in areas where there is greater air circulation. It is suggested for the elderly to have greater attention and care when getting up.

Possible complications of hypotension

Experts say that the most feared of these is syncope (loss of consciousness)—which may be associated with hypotension but also signal more severe conditions. Related risks are trauma—to the skull, upper or lower limbs, stroke (cerebrovascular accident) and cardiac arrest.

Another possibility is the shock that arises from medical situations such as the loss of acute blood volume in an inpatient, or as a consequence of serious infections, such as pyelonephritis, this is also an evolution of the urinary infection that can lead to sepsis.

How to help a person with hypotension?

The general rule is to keep the patient lying down, sitting or crouching for a period of time, keeping them hydrated.

Popular belief says that salt under the tongue can help. However, there is no scientific evidence to justify this measure. Nevertheless, consuming adequate amounts of salt is a useful practice that can be adopted by people on a salt-restricted diet for some reason.

Sources: Minna Moreira Dias Romano, professor at FMRP-USP (Faculty of Medicine of Ribeirão Preto, University of São Paulo) in the Department of Clinical Medicine, working in the field of cardiology; Brivaldo Markman, head of the Cardiology Service of the Hospital das Clínicas at UFPE (Federal University of Pernambuco), a unit linked to Ebserh (Brazilian Company of Hospital Services) and full professor of the discipline of cardiology at the same institution; Rafael Mendonça Rey dos Santos, family doctor and professor at the School of Medicine at PUC-PR (Pontifical Catholic University of Paraná). Technical review: Brivaldo Markman.

References: AHA (American Heart Association); Sharma S, Hashmi MF, Bhattacharya PT. Hypotension. [Atualizado em 2021 Aug 14]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2021 Jan-. Available at: https://www.ncbi.nlm.nih.gov/books/NBK499961/.