Hypotension - Causes and Symptoms

Definition

Hypotension is a condition in which the maximum (or systolic) arterial pressure is equal to or less than 90 milligrams of mercury (mmHg) and the minimum (or diastolic) is equal to or less than 60 mmHg.

The causes can be multiple and of different relevance. The most important factors that can induce a drop in pressure are the reduction of cardiac output, the mass of circulating blood and peripheral resistance.

In some people, low blood pressure is a constant, probably due to a genetic predisposition, and almost never causes problems. On the other hand, subjects whose values tend to be normal may be affected by a possible drop in blood pressure.

In most cases, it is a temporary alteration, but when the hypotensive crisis lasts a long time or the episode is particularly intense, it is advisable to seek medical attention, since it could be the symptom of more serious disorders, such as a hemorrhage internal, adrenal insufficiency or heart disease. Furthermore, if hypotension is prolonged and is not adequately treated it can lead to multi-organ dysfunction.

Hypotension can be associated with symptoms such as tiredness, difficulty concentrating, drowsiness, dizziness, palpitations, a feeling of weakness in the legs, cold sweat, nausea and vision problems. Sudden drops in pressure can also lead to a reduced blood supply to the brain with the risk of fainting and falling to the ground; this exposes the elderly to the danger of serious fractures.

The most common causes of hypotension are dehydration, sudden changes in posture (especially when moving quickly from a lying position to an upright position), a drop in sugar and strong emotion. In some cases, the drop in blood pressure is a side effect of some drugs, such as vasodilators, diuretics and tricyclic antidepressants. Excessive alcohol consumption can also reduce pressure.

Hypotension can be caused by burns, endocrine diseases, anemia, gastroenteritis, metabolic acidosis, pregnancy or vitamin deficiencies. It is necessary to know that there are also certain conditions that can promote the persistence of low blood pressure, such as prolonged heat, long-lasting bedding (for example, due to illness, surgery or fracture) and consistent and continuous loss of fluids (eg prolonged vomiting, diarrhea and profuse sweating). Furthermore, hypotension may be secondary to prolonged convalescence after bacterial and viral infections.

The origin of this symptom can be cardiogenic causes, such as myocardial infarction, heart failure, pericardial tamponade, severe obstructive valvulopathy and progression of chronic myocardiopathy. Possible conditions predisposing to hypotension are also peripheral venous insufficiency, tachyarrhythmias or bradyarrhythmias and alteration of vasomotor tone (as in hypokalaemia).

Sudden bleeding, sepsis, anaphylactic shock and pulmonary embolism may also be the basis for the decrease in blood pressure. Other causes of hypotension include dysfunctions of the neurovegetative system secondary to Parkinson's disease, spinal cord neoplasms and diabetic or nutritional neuropathy.