The Pharmacologic Treatment of Hypotension
- THIS PAGE: Definition of Hypotension and its Causes
- Page 2: Rationale for Pharmacologic Treatment of Hypotension
- Page 3: Drugs Used to Treat Hypotension
Definition of Hypotension and its Causes
Causes of Hypotension:
Reduced Cardiac Output
- Hypovolemia
(hemorrhage; dehydration) - Impaired venous return
(orthostatic hypotension; gravity) - Reduced cardiac contractility
(heart failure; cardiogenic shock) - Reduced ventricular rate
(sinus bradycardia; AV nodal block) - Elevated ventricular rate
(tachycardia; fibrillation) - Autonomic dysfunction
(autonomic neuropathy)
Reduced Systemic Vascular Resistance
- Systemic vasodilation
(septic shock; anaphylaxis) - Autonomic dysfunction
(autonomic neuropathy)
Hypotension is a physiologic state in which the arterial blood pressure is abnormally low. For an adult, hypotension exists when the systolic pressure is less than 90 mmHg and the diastolic pressure is less than 60 mmHg. Because arterial pressure is determined by cardiac output, venous pressure and systemic vascular resistance (Click here for more details), a reduction in either one or all of these variables can lead to hypotension. Causes of hypotension include:
- Hypovolemia due to hemorrhage or dehydration (reduces venous pressure and cardiac output).
- Blood volume redistribution caused by postural changes or gravitational forces (reduces venous pressure and cardiac output).
- Reduced cardiac output caused by acute or chronic heart failure (e.g., cardiogenic shock), arrhythmias, or autonomic neuropathy.
- Reduced systemic vascular resistance due to loss of sympathetic tone caused by drugs or autonomic neuropathy, or vasodilation caused by sepsis (septic shock) or anaphylaxis.
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Rationale for Pharmacologic Treatment
Revised 03/14/07