Vasoconstriction

Definition

Vasoconstriction is the narrowing of blood vessels by contraction of vascular smooth muscle, reducing vessel diameter, blood flow, and increasing blood pressure.

Triggers

• Sympathetic nervous system (fight-or-flight)
• Cold exposure
• Stress, anxiety
• Medications: norepinephrine, phenylephrine, epinephrine, vasopressin
• Nicotine
• Angiotensin II

Clinical Uses

Shock management: vasopressors (norepinephrine) maintain perfusion. Local anesthesia: epinephrine added to prolong anesthesia and reduce bleeding. Severe bleeding: decongestants vasoconstrict to reduce nosebleed.

Nursing Considerations

Monitor BP, perfusion, and IV site closely when administering vasopressors. Extravasation causes tissue necrosis (antidote: phentolamine). Raynaud's phenomenon: vasospasm of digits on cold exposure. Teach warmth, smoking cessation.

NCLEX Relevance

Vasopressors extravasation → phentolamine.