Why do we have low blood pressure

Dizziness, weakness and blurred vision are some of the typical signs of low blood pressure, but few know why they appear and how to counteract them.

Almost daily we hear about the risks of hypertension for the heart and arteries, how widespread it is and how essential it is to prevent and counteract it. Hypotension, on the other hand, is a much less considered problem than high blood pressure, probably because it is generally not associated with severe acute events or sequelae that are worrying about long-term health.

This does not mean that having too low pressure can lead to considerable discomfort and some non-negligible risks, especially due to possible dizziness.

It depends on the individual case: if, for example, it is an elderly person who is affected or a person engaged in professional activities that require attention, balance, use of machinery and / or tools that increase the probability of falls and accidents, hypotension can be responsible for events of considerable severity.

For this reason, especially in summer, it is important to recognize the symptoms of hypotension from the onset and learn to prevent and counteract them, correcting, as far as possible, the mechanisms that determine it and adopting simple behavioral strategies that can favor the return to normal blood pressure values. Treatment with certain medications can also help raise blood pressure too low, but people who really need to take them are a minority.

Typical symptoms and causes of low blood pressure

Dizziness or dizziness, blurred vision, weakness, exhaustion, light-headedness, nausea and loss of muscle control, feeling heartbeat (due to the so-called reflex tachycardia), difficulty concentrating, cold skin, weak and rapid pulse and, in the most severe cases, fainting are the unmistakable signs of low blood pressure , corresponding to the presence of maximum (systolic) pressure values < 90 mmHg and minimum pressure (diastolic) < 60 mmHg.

The reference values (according to the WHO) of blood pressure are given in the table below:

Blood pressure	Diastolic (minimum)	Systolic (maximum)
Optimal	< 80 mmHg	< 120 mmHg
Normal	< 85 mmHg	< 130 mmHg
Normal-high	85-89 mmHg	130-139 mmHg
Grade 1 hypertension – borderline	90-94 mmHg	140-149 mmHg
Grade 1 hypertension – mild	95-99 mmHg	150-159 mmHg
Grade 2 – moderate hypertension	100-109 mmHg	160-179 mmHg
Grade 3 hypertension – severe	> 110 mmHg	> 180 mmHg
Borderline isolated systolic hypertension	< 90 mmHg	140-149 mmHg
Isolated systolic hypertension	< 90 mmHg	> 150 mmHg

At the origin of a hypotensive crisis, in those who already have low blood pressure or a poor hemodynamic compensation capacity, there may be trivial causes such as:

– stay too long in a warm environment, especially if the heat is also accompanied by a high humidity, as is the case with a very sultry summer day, a greenhouse, a steam room, a subway car during rush hour;

– get up quickly from a sitting or lying position, for example from the bed, sofa or chair (in this case it is called “orthostatic hypotension”);

– take a hot bath or shower a little too long.

Even not drinking enough and not replenishing lost liquids and mineral salts (especially sodium, chlorine, potassium and magnesium) when you have abundant sweating and / or after practicing intense physical activity (especially if in hot environments) can cause annoying pressure drops and fainting, because, in doing so, it prevents the body from maintaining the correct hydroelectrolyte balance, essential to ensure a sufficient volume of blood in the circulatory tree (volume) and to allow the kidneys to properly regulate pressure values.

Other causes of hypotension may be psychological or neurological in nature. A sudden and stressful event, a fright, unexpected bad news or a high sensitivity towards particular objects (such as needles, blood, blades, etc.) o situations (performing dental interventions or dressings, proximity or contact with animals considered gruesome, etc.) They can trigger the so-called “vagal reaction”, that is, an activation of the vagus nerve which, among its many functions, also has that of modulating the heart rate.

Vagal reactions in stressful situations cause an abrupt and sudden reduction in the speed of contraction of the heart, on which depends the force with which the blood is pushed into the arteries and, therefore, the pressure it exerts on their walls. The result is usually a sudden fainting, mainly due to the sudden decrease in blood pressure and blood supply to the brain.

Although it may seem strange, since generally among the tips for those with low blood pressure there is to eat to get it up, even good food can be responsible for lowering the pressure. A hearty meal, in fact, especially if rich in carbohydrates, can end with episodes of hypotension. In this case, the origin of the abnormal pressure drop is linked to the massive secretion of insulin, promoted by ingested sugar (the nutrient from which the body draws a lot of energy), and to the recall of large amounts of blood to the level of the gastrointestinal system to support digestion, which is thus removed from the general circulation.

In these cases, the hypotensive effect is more marked if, together with carbohydrates (pasta, bread, potatoes, rice, sweets, etc.) wine, beer or spirits are also taken. Alcohol, in fact, has in itself a well-known and widely tested vasodilating and, therefore, hypotensive effect, which is added to the reduction in the volume of blood in circulation (hypovolemia) determined by the meal, amplifying the drop in pressure.

A lowering of blood pressure values can also be caused by alterations in the normal electrical activity of the heart such as those caused by bradycardia (literally, the disorder due to a “slow heart”) or, more rarely, by anaphylactic shock (consequence of allergic reactions), by a myocardial infarction and by cardiac arrhythmias (often due to heart valve problems).

Factors that increase the risk of low blood pressure

In addition to the very common ones, already mentioned, there are many other factors that can favor a lowering of blood pressure.

The first is age: as you get older, your blood pressure calibration system becomes less and less efficient. The arteries stiffen and are able to compensate less for the variations in the volume of blood flowing inside them, the kidneys begin to regulate diuresis and the reabsorption of mineral salts less precisely, the heart (even if healthy) begins to be a little tired and to pump blood into the circulation with less conviction, The level of “positive” basal stress is loosened and with it the whole set of cortisol-based mechanisms that contribute to raising the pressure.

With advancing age, then, almost invariably, cardiovascular, renal, metabolic and neurological diseases take over that make blood pressure controls very imprecise, determining in some cases hypertension and in others tendency to low blood pressure.

Among the typical diseases of the elderly that see hypotension among the characteristic manifestations should be remembered: heart failure, dilated cardiomyopathy, stenosis of the aorta, peripheral venous insufficiency, Parkinson’s disease, dysfunctions of the autonomic nervous system (including the aforementioned vagus nerve).

In addition to the intrinsic organic alterations, to these and other diseases, to determine pressure drops can be the drugs used to counteract them. Those most at risk in this sense are diuretics (furosemide, hydrochlorothiazide), antihypertensive drugs (in particular, ACE inhibitors), vasodilators (nitrates), alpha-blockers and beta-blockers, some antidepressants (tricyclics, MAOIs), antipsychotics and barbiturates, medicines used against erectile dysfunction and some hypoglycemic agents (as well as hypoglycemia of any origin).

Another frequent condition in the elderly, but which can cause dangerous hypotensive crises and important organic imbalances at any age, is dehydration, characterized by a generalized reduction in the volume of body fluids and, therefore, also in the volume.

More or less significant dehydration conditions may be related to diabetes or the habit of drinking too little compared to the basic needs of the body (as often happens in children and the elderly, who perceive less the stimulus of thirst) or to a transient increase in the need for liquids due to environmental conditions (heat, dry climate, etc.), fever, strenuous physical activity, vomiting or diarrhoea, abuse of laxatives, etc.

In women of childbearing age, low blood pressure conditions are frequent, both for reasons related to the direct action of female hormones on blood vessels (of which they regulate the tone and, therefore, the degree of vasoconstriction and vasodilation) and due to periodic blood loss with menstrual flow (which is then subtracted from the body, reducing the volume).

The situation does not improve with pregnancy. In the first three months of gestation, hormonal changes and the cardiocirculatory reorganization necessary to prepare the woman’s body to welcome the fetus lead to a modest reduction in blood pressure, which can be well tolerated or even favorable if the woman was initially normal or hypertensive, but a bit annoying for those who already had low blood pressure before conception. The phenomenon is, however, transient and regresses spontaneously starting from the 2nd trimester of pregnancy.

Other hormonal causes of hypotension are related to thyroid and parathyroid disorders and adrenal gland failure (Addison’s disease), resulting in reduced cortisol production.

Even blood loss of various kinds (evident bleeding or more subtle internal micro-leaks) can lead to a similar reduction in volume and, therefore, blood pressure. A type of blood loss that is particularly important to pay attention to, especially after the age of 50, is the one that affects the gastrointestinal system (recognizable by examining the presence of traces of blood in the stool) since it can be the indicator of an intestinal neoplasm.

Un altro problema ematologico che annovera la pressione bassa tra le proprie manifestazioni è l’anemia di qualunque origine. Forme comuni di anemia sono spesso associate a carenza di ferro e/o folati (in particolare, la vitamina B12). Per assicurarsi un apporto quotidiano corretto del primo è necessario inserire nella dieta cibi come carni rosse e bianche, lenticchie, cioccolato fondente, cacao amaro, tonno e spinaci, preferibilmente aggiungendo alle ricette una fonte di vitamina C (limone, pomodori, peperoni ecc.), che facilita l’assorbimento del ferro. Per fare il pieno di vitamina B12, invece, sono utili cibi come fegato, pesci grassi del mare del Nord (sgombro, aringhe, sardine, tonno, merluzzo) e cereali arricchiti oppure si può ricorrere a integratori mirati (su consiglio del medico).

Come monitorare l’ipotensione

Controlling blood pressure by measuring blood pressure regularly is a form of prevention, a valid tool with which to safeguard health and well-being. In fact, in general, those who suffer from pressure disorders know it well.

On the other hand, measuring blood pressure is always easier and faster: now you can do it from home with a common automatic meter or, in its absence, requesting the assistance of doctors and pharmacists.

Once you have passed the age of 40, then, the only home measurement, although regular and correct, becomes insufficient and then it is necessary to undergo periodic check-ups every five years. In these cases, the physical examination conducted by the family doctor is associated with the interpretation of the results of tests and analyzes such as:

• blood tests, through which the levels of blood sugar, cortisol and red blood cells are investigated;
• urine tests, to look for infections;
• electrocardiogram, echocardiogram and stress tests that allow to detect any cardiac disorders;
• measurement of blood pressure for 24 consecutive hours using a device called a pressure holter;
• radiological examinations (CT and chest X-ray) useful to evaluate the state of the heart and lungs;
• Passive orthostatic stimulation test.

How to prevent the pressure from dropping too much

To avoid the discomfort of low blood pressure and improve the level of well-being, ensuring a correct supply of nutrients and oxygen to all organs, in most cases it is sufficient to adopt some dietary and lifestyle measures and try to minimize the impact of the factors that can promote its reduction, starting from the optimization of the treatment of any predisposing diseases.

On the nutrition front, in addition to the recommendation to take sufficient amounts of liquids in any form (but avoiding alcoholic beverages and very diuretic ones), the main suggestions to raise blood pressure a little consist in slightly increasing sodium intake (using common table salt, possibly iodized, but not the low-sodium versions), in consuming adequate quantities of aged cheeses (30-40 g, maybe added in recipes with vegetables) and red meats (100-150 g), as well as fresh fruits and vegetables in abundance (rich in liquids, minerals and vitamins).

A precious help for those who have a tendency to hypotension (and have no problems with water retention or potassium deficiency) comes from licorice, notoriously able to promote the raising of blood pressure values by stimulating greater sodium reabsorption by the kidneys. Given that the effects of licorice (in the form of logs, candies, extracts in drops, herbal teas, infusions, etc.) can be marked, it is preferable to resort to this, as well as other natural remedies, in moderation, perhaps after asking the opinion of the doctor, especially if you are elderly or suffer from other diseases.

The same applies to coffee and other drinks (or foods) that contain caffeine, theobromine or theophylline, able to improve vascular tone and stimulate the contraction of the heart, thus increasing blood pressure, albeit transiently. The important thing is not to overdo it, having the foresight to contact the doctor in case you have doubts and concerns (or, to a cardiologist, if there is already a pathology affecting the heart). In general, the intake of a maximum of 3-4 coffees or teas a day (or equivalent portions of caffeine in other drinks) does not create problems even for those suffering from non-serious heart diseases, but to avoid mistakes it is always preferable to have the doctor’s ok.

The intake of coffee or tea is definitely advisable in the morning and after meals, when the pressure tends to be lower. Another useful recommendation to make the moment of awakening after the night rest less problematic if you suffer from low blood pressure is to get out of bed very slowly, resting your feet on the ground one at a time and waiting a few tens of seconds before putting force on your legs: it will serve to avoid dizziness, loss of balance and dangerous falls. The same applies when you have to get back on your feet after sitting for more than a few minutes.

A real medicine, both in case of hypotension and hypertension, is to practice physical activity regularly.

The physical activity understood here, however, is not that of exhausting sessions in the gym or long hours of sport, which, as we have seen, end up being weak and counterproductive, but the constant and balanced one that does not subject the body to excessive effort.

Moderate aerobic movement, for at least 30-60 minutes a day, has an extraordinarily positive effect on the cardiovascular and musculoskeletal systems. In particular, those suffering from hypotension benefit in terms of improving the heart’s working capacity, maintaining better vascular tone and strengthening the muscles that help stimulate the return of venous blood from the feet and legs to the heart (“plantar pump”, calves).

The movement in an upright position and associated with gravitational stimuli, moreover, stimulates the mechanisms of regulation of blood pressure at the renal level (renin-angiotensin-aldosterone system), bringing it to values closer to normal. The ideal activities to achieve all these favorable outcomes and improve overall well-being are running, walking, cycling, bodyweight gymnastics and dancing; Swimming is equally advantageous on the cardiovascular and muscular level, but being practiced in a horizontal position and with the support of water does not act on the regulation of orthostatic pressure.

Only in patients with more severe hypotension and not adequately compensated by the combination of these interventions, medicine provides for the use of drugs capable of raising blood pressure values through different mechanisms, such as:

– increased activity of the adrenal glands (steroids such as fludrocortisone) or vascular tone (vasoconstrictors)

– inhibition of diuresis (vasopressin, desmopressin)

– stimulation of the production of red blood cells (erythropoietin)

All possible pharmacological remedies for low blood pressure should be prescribed by the doctor after careful evaluation of the extent and causes of hypotension, age and the general clinical picture of the sufferer.