Vasopressors
Key Points
- Vasopressors (vasoactive drugs) increase blood pressure by increasing vasoconstriction and/or cardiac output — used when shock or severe hypotension threatens tissue perfusion.
- Must be administered via central venous access whenever possible — peripheral extravasation causes tissue necrosis.
- Correct hypovolemia FIRST before initiating most vasopressors — vasopressors cannot compensate for inadequate volume.
- Continuous cardiac monitoring, frequent vital sign assessment, and IV site inspection are mandatory nursing priorities.
- Common agents: norepinephrine (first-line septic shock), dopamine (cardiogenic shock, dose-dependent effects), epinephrine (anaphylaxis, cardiac arrest), dobutamine (cardiogenic shock inotrope).
Mechanism of Action by Agent
Vasopressors stimulate adrenergic receptors to increase blood pressure:
| Agent | Receptor Activity | Primary Effect | Primary Use |
|---|---|---|---|
| Norepinephrine (Levophed) | Alpha-1 (dominant) + Beta-1 (moderate) | Vasoconstriction + ↑ HR/contractility | Septic shock, cardiogenic shock |
| Dopamine (dose-dependent) | Low dose: dopaminergic; Intermediate: Beta-1; High dose: Alpha-1 | Dose-dependent: vasodilation → inotropy → vasoconstriction | Cardiogenic shock, profound hypotension |
| Epinephrine | Alpha-1, Beta-1, Beta-2 | Vasoconstriction + bronchodilation + ↑ cardiac output | Anaphylaxis, cardiac arrest |
| Dobutamine | Beta-1 (dominant) | ↑ Myocardial contractility (inotropy) without significant vasoconstriction | Cardiogenic shock (heart failure) |
| Vasopressin | V1 receptors (vascular) | Vasoconstriction (non-adrenergic) | Septic shock adjunct, vasodilatory shock |
Dopamine dose-response relationship:
- Low doses (0.5–2 mcg/kg/min): dopaminergic receptor → renal vasodilation, ↑ urine output
- Intermediate doses (2–10 mcg/kg/min): Beta-1 → ↑ heart rate and cardiac output
- High doses (>10 mcg/kg/min): Alpha-1 → peripheral vasoconstriction → ↑ blood pressure
Indications
- Septic shock — norepinephrine is first-line after adequate fluid resuscitation
- Cardiogenic shock — dopamine, dobutamine, norepinephrine (after infarction or severe heart failure)
- Anaphylactic shock — epinephrine is first-line (IM or IV depending on severity)
- Hypovolemic shock — volume replacement is primary; vasopressors used only as bridge
- Cardiac arrest — epinephrine every 3–5 minutes IV/IO during CPR
Nursing Assessment
NCLEX Focus
Vasopressors are high-alert medications. Never start a vasopressor without correcting volume deficit first. Peripheral extravasation of norepinephrine, dopamine, or epinephrine causes severe tissue necrosis — check IV site every 1–2 hours when using peripheral access and anticipate urgent central line placement.
Pre-administration:
- Assess blood pressure, heart rate, SpO₂, and urine output (target ≥30 mL/hr)
- Ensure IV access is patent; central venous access preferred
- Verify and correct hypovolemia — fluid bolus before initiating norepinephrine or epinephrine
- Verify titration order (vasopressors are titrated to target MAP, typically MAP ≥65 mmHg)
Contraindications and cautions:
- Dopamine: contraindicated in pheochromocytoma, uncorrected tachyarrhythmias, ventricular fibrillation
- Norepinephrine: use with extreme caution in hypovolemia (peripheral ischemia risk)
- Epinephrine: use caution in coronary artery disease (↑ myocardial oxygen demand)
Nursing Interventions
Administration:
- Administer via infusion pump — rate changes must be precise
- Use central venous catheter (CVC) when possible — peripheral vasopressors require vigilant site monitoring
- Never bolus vasopressors — titrate gradually based on MAP and clinical response
- Confirm and document dose expression in mcg/kg/min (or ordered unit) when converting from pump mL/hr and solution concentration.
- Do not mix vasopressors with alkaline solutions (e.g., sodium bicarbonate) — chemical incompatibility
Monitoring:
- Continuous cardiac monitoring — dysrhythmias (ventricular tachycardia, atrial fibrillation, widened QRS)
- Blood pressure every 5–15 minutes (or continuous arterial line monitoring in ICU)
- Urine output hourly — target ≥30 mL/hr (indicator of adequate perfusion)
- Level of consciousness and skin perfusion (warm extremities, capillary refill <3 sec)
Extravasation emergency:
- Inspect IV site every 1–2 hours for redness, swelling, pallor, or skin blanching
- If extravasation suspected: stop infusion immediately, aspirate, notify provider
- Antidote for extravasation: phentolamine (alpha-blocker) injected subcutaneously around site
- Do not apply heat — worsens tissue damage
Tissue Necrosis Risk
Peripheral extravasation of norepinephrine or dopamine causes severe local tissue ischemia and may require surgical debridement. Use central venous access whenever possible. Inspect peripheral infusion sites every 1–2 hours. Report any signs of extravasation immediately.
Related Concepts
- cardiovascular-system — Adrenergic receptor distribution and hemodynamic principles underlying vasopressor effects.
- fluid-volume-deficit-hypovolemia-and-dehydration — Volume resuscitation must precede vasopressor initiation in hypovolemic shock.
- systematic-ecg-interpretation-and-dysrhythmia-triage — Cardiac dysrhythmias as vasopressor adverse effects requiring monitoring.
- hypersensitivity-types-and-anaphylaxis-response — Epinephrine as first-line vasopressor in anaphylactic shock.
- cvad-indications-and-device-selection — Central venous access for safe vasopressor administration.
- iv-push-medication-safety-principles — High-alert medication safety principles applied to vasopressor infusions.
Self-Check
- A client in septic shock has received 30 mL/kg crystalloid bolus, and MAP remains at 55 mmHg. The provider orders norepinephrine. What is the priority nursing assessment before initiating the infusion?
- A nurse notices the IV site where dopamine is infusing is pale, swollen, and the patient reports burning pain. What is the immediate nursing action?
- Why does the dose of dopamine matter so much in clinical practice, and what effect occurs at each dose range?