Pressor

Pressor

A pressor is a term used in the medical field to describe any agent or mechanism that causes an increase in blood pressure. This can refer to both endogenous substances, such as hormones, and exogenous drugs that are administered to patients to manage hypotension (low blood pressure). Pressors are critical in the management of various medical conditions, particularly in critical care settings.

Physiological Mechanisms

Pressors work by influencing the cardiovascular system to increase blood pressure. This can be achieved through several mechanisms:

• Vasoconstriction: Many pressors act by causing the blood vessels to constrict, which increases vascular resistance and subsequently raises blood pressure.
• Increased Cardiac Output: Some pressors increase the heart rate or the force of cardiac contraction, thereby increasing cardiac output and blood pressure.
• Fluid Retention: Certain pressors can influence the kidneys to retain fluid, increasing blood volume and pressure.

Endogenous Pressors

The body naturally produces several pressor substances, including:

• Norepinephrine: A neurotransmitter and hormone that acts as a potent vasoconstrictor.
• Epinephrine: Also known as adrenaline, it increases heart rate and cardiac output.
• Angiotensin II: A peptide hormone that causes blood vessels to constrict and stimulates the release of aldosterone, promoting sodium and water retention.

Exogenous Pressors

In clinical practice, synthetic or natural pressor agents are used to treat hypotension. Commonly used pressors include:

• Norepinephrine (Levophed): Often the first-line agent in septic shock.
• Epinephrine: Used in cardiac arrest and anaphylaxis.
• Dopamine: Used in certain cases of heart failure and shock.
• Phenylephrine: A selective alpha-1 adrenergic receptor agonist used to increase blood pressure.

Clinical Applications

Pressors are primarily used in:

• Septic Shock: To counteract the profound vasodilation and hypotension.
• Cardiogenic Shock: To improve cardiac output and perfusion.
• Anaphylactic Shock: To reverse vasodilation and bronchoconstriction.

Side Effects and Considerations

While pressors are life-saving, they can have significant side effects, including:

• Tissue Ischemia: Due to excessive vasoconstriction.
• Arrhythmias: Particularly with agents that increase heart rate.
• Hypertension: Overcorrection of blood pressure can lead to complications.

Also see

• Vasopressor
• Hypotension
• Septic shock
• Cardiogenic shock
• Anaphylaxis

Resources

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Source: Data courtesy of the U.S. National Library of Medicine. Since the data might have changed, please query MeSH on Pressor for any updates.

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