Causes and Types of Arterial Hypotension
Arterial hypotension is a pathological condition defined primarily by a drop in systolic blood pressure below 105 mm Hg. Hemodynamically, this pressure drop is driven by three main factors: first, a reduction in cardiac output; second, a decrease in total peripheral resistance (TPR); and third, a combination of both factors.
Clinically, hypotension is classified into two major groups:
- Acute form: Develops rapidly and is life-threatening. This includes severe conditions such as various types of shock, vascular collapse, and acute massive blood loss.
- Chronic form: Divided into primary (idiopathic) and secondary. Secondary chronic hypotension is a consequence of other pathologies and strictly requires appropriate pharmacotherapy.
Classification of Vasopressors
Vasopressors are used for the pharmacological correction of low blood pressure. Depending on their primary mechanism affecting hemodynamics, these drugs are divided into two main groups:
- Agents that increase cardiac output and peripheral vascular tone.
These drugs have a combined effect on the cardiovascular system. The main pharmacological group here consists of $\alpha, \beta$-adrenoreceptor agonists. The classic and most prominent representative of this group is epinephrine, also known in medical practice as adrenaline.
- Agents that predominantly increase peripheral vascular tone.
These drugs primarily act to constrict the vascular bed. This group is further subdivided based on chemical structure and sites of action:
- $\alpha$-Adrenoreceptor agonists. Key representatives include norepinephrine (norepinephrine acid tartrate) and phenylephrine (mesaton).
- Polypeptide agents. The main representative is angiotensinamide, also known as hypertensin.
Clinical Application of Adrenomimetics
Adrenomimetics are potent tools in clinical practice. The primary indication for their administration is acute arterial hypotension, when immediate intervention is required to restore adequate circulation.
There are strict rules regarding the routes of administration for these drugs. The primary and safest route is intravenous administration via controlled infusion. However, there is an exception: phenylephrine has specific properties that allow it to be administered not only intravenously, but also subcutaneously and intramuscularly.
Special attention should be given to the clinical use of epinephrine. Due to its ability to rapidly restore hemodynamics, it is recognized as the drug of choice in the management of anaphylactic shock, demonstrating exceptionally high clinical efficacy in this setting.
Pharmacological Profile of Angiotensinamide
Angiotensinamide is a unique polypeptide agent. Structurally, it is an amide of angiotensin II.
Its mechanism of action differs fundamentally from adrenomimetics: the drug directly stimulates specific angiotensin receptors located in arteriolar walls. This stimulation results in a rapid and extremely potent vasoconstrictive effect. Notably, the pressor potency of angiotensinamide significantly exceeds that of epinephrine.
The drug's action has a clear localization. The most pronounced vasoconstriction is observed in the visceral vascular bed, as well as in the skin and renal vessels.
In addition to its direct effect on vascular tone, angiotensinamide significantly affects water and electrolyte balance via hormonal mechanisms. It actively stimulates the production of aldosterone. This hormonal effect results in marked retention of sodium and water in the patient's body, which naturally leads to an increase in extracellular fluid volume and additionally helps maintain blood pressure.