Shock / Hemodynamics
Vasopressors
Overview of vasopressor use in distributive shock, distributive shock pathophysiology, and common pressor agents used in the SICU.
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Distributive Shock and Vasopressors
Distributive shock* is caused by pathologic dilation of peripheral vascular beds. When peripheral vascular beds dilate: • Blood...Section
Distributive Shock and Vasopressors
Distributive shock* is caused by pathologic dilation of peripheral vascular beds. When peripheral vascular beds dilate: • Blood...- Distributive shock* is caused by pathologic dilation of peripheral vascular beds. When peripheral vascular beds dilate:
- Blood pools in the periphery
- Blood does not return to the central circulation (right heart)
- This loss of preload can spiral into cardiovascular collapse
- Vasopressors* are the tools used to combat distributive shock. They act on vascular smooth muscle receptors to constrict the vascular beds.
Mechanism of Most Pressors
- Most ICU vasopressors are synthetic analogs of endogenous catecholamines (e. g., norepinephrine, epinephrine)
- They work via adrenergic receptors on vascular smooth muscle cells
- Vasopressin acts via a separate set of receptors — the 'V' receptors on vascular smooth muscle
Common Vasopressors in the SICU
Property • Effect • α-adrenergicSection
Common Vasopressors in the SICU
Property • Effect • α-adrenergicNorepinephrine (First-line for most distributive shock)
| Property | Effect |
|---|---|
| α-adrenergic | Peripheral vasoconstriction |
| β-adrenergic | Cardiac inotrope, coronary vasodilation |
- Clinical use:* First-line agent for septic shock and most forms of distributive shock.
Epinephrine
| Property | Effect |
|---|---|
| α₁-adrenergic | Peripheral vasoconstriction |
| β₁-adrenergic | Cardiac inotrope |
- Clinical use:* Second-line or adjunct; cardiac arrest, anaphylaxis.
Vasopressin
| Property | Effect |
|---|---|
| V₁ receptors | Vasoconstriction via IP₃ signal transduction and Rho-kinase pathway |
- Clinical use:* Adjunct to norepinephrine in refractory septic shock; also used in post-cardiac arrest and neurogenic shock.
Important Clinical Reminders
Do not use vasopressor protocols or dosing guidance without attending direction and institutional review.Section
Important Clinical Reminders
Do not use vasopressor protocols or dosing guidance without attending direction and institutional review.Do not use vasopressor protocols or dosing guidance without attending direction and institutional review.
- Vasopressor dosing is patient-specific and depends on hemodynamic response, comorbidities, and goals of care
- Monitoring requirements (arterial line, central venous access) must be in place
- Wean vasopressors in concert with volume resuscitation
- Avoid abrupt discontinuation — taper to assess volume status response