Vasopressors & Inotropes Study Char
1. Core Terminology
Term | Meaning | ATI/NCLEX Tip |
Inotrope | ↑ contractility → ↑ CO | Watch for ↑ myocardial oxygen demand (tachycardia, ischemia risk) |
Chronotrope | ↑ HR | Too high → ↓ filling time & CO |
Dromotrope | ↑ AV node conduction | Dysrhythmias possible |
Bathmotrope | ↑ myocardial excitability | Can trigger arrhythmias |
Lusitrope | ↑ relaxation | Helps ventricular filling |
2. Receptors & Effects
Receptor | Location | Effect | Nursing Tip |
Alpha-1 | Vascular smooth muscle | Vasoconstriction ↑ SVR ↑ BP | Monitor perfusion (skin, UOP) |
Beta-1 | Heart | ↑ HR, ↑ contractility | Watch for tachycardia, dysrhythmias |
Beta-2 | Lungs/vasculature | Bronchodilation, mild vasodilation | Helpful in asthma/anaphylaxis |
Dopaminergic | Renal artery | Vasodilation → ↑ renal perfusion | “Renal-dose dopamine” (low-dose) |
Vasopressin V1 | Vascular smooth muscle, platelets | Vasoconstriction, ↑ clotting | Watch for ischemia |
Vasopressin V2 | Renal tubules | Water retention (ADH effect) | Monitor Na+, UOP, signs of fluid overload |
3. Endogenous vs. Exogenous
Chemical | Endogenous Role | Exogenous Use |
Dopamine | Precursor to NE/Epi, regulates renal perfusion, ↓ GI motility, ↓ insulin | Shock states (renal perfusion, contractility, vasoconstriction) |
Norepinephrine (NE) | Stress response, ↑ BP/CO | First-line in septic/distributive shock |
Epinephrine (Epi) | Fight/flight (↑ HR, ↑ CO, vasoconstriction, bronchodilation) | Anaphylaxis, bradycardia, cardiac arrest, severe shock |
Vasopressin (ADH) | Osmoregulation, backup BP control | Refractory shock, GI bleed, DI |
4. Drug Profiles
Dopamine
Dose Range | Receptor Effect | Result |
Low (1–4 mcg/kg/min) | Dopaminergic | ↑ Renal blood flow |
Medium (4–10) | β1, some α1 | ↑ Contractility & CO |
High (10–20) | α1 dominant | Vasoconstriction, ↑ SVR |
Nursing: ECG (tachydysrhythmias), BP, distal perfusion, UOP, gut function
Norepinephrine (Levophed)
Indication: First-line for septic/distributive shock
Receptors: Mainly α1 → vasoconstriction, some β1
Dose: 0.05–1 mcg/kg/min
Nursing: Watch for peripheral ischemia (cold/blue fingers, ↓ pulses), BP, UOP, mental status
Epinephrine
Indication: Anaphylaxis, cardiac arrest, severe shock, bradycardia
Receptors: α1, α2, β1, β2
Effects: ↑ HR, ↑ CO, vasoconstriction, bronchodilation, ↑ O2 demand
Nursing: ECG, BP, UOP, perfusion, GI ischemia (splanchnic hypoperfusion)
Vasopressin (ADH)
Indication: Refractory shock, GI bleed, DI
Receptors: V1 (vasoconstriction), V2 (H₂O reabsorption)
Dose: 0.01–0.04 units/min
Nursing: Watch for bradycardia, monitor Na+, perfusion, fluid overload
Other Vasopressors
Drug | Action | Nursing Tip |
Dobutamine | β1 agonist → ↑ contractility, mild vasodilation | For HF, cardiogenic shock |
Milrinone | PDE-3 inhibitor → ↑ contractility, vasodilation | Watch for hypotension, arrhythmias |
Phenylephrine | Pure α1 agonist → vasoconstriction | Reflex bradycardia risk |
Isoproterenol | β1 & β2 → ↑ HR, contractility, bronchodilation | Rarely used; arrhythmia risk |
Nitroprusside | Potent vasodilator → ↓ afterload | Watch for cyanide toxicity |
5. Case Study (Septic Shock)
Scenario | Key Points | ATI Angle |
1 | Septic shock s/p 2L NS, MAP 59 | Start Norepinephrine (first-line) |
2 | Still hypotensive on NE + fluids, lactate ↑, Cr ↑ | Add Vasopressin or Epinephrine; consider hydrocortisone if refractory |
Assessment: UOP, perfusion, lactate, mental status | ||
ATI Tip: Always titrate to maintain MAP ≥ 65 mmHg |
6. Safety & Nursing Priorities
Extravasation:
Stop infusion, D/C IV, elevate limb
Warm compress
Infiltrate phentolamine
Topical nitroglycerin
Debridement/grafting PRN
General Nursing:
Central line preferred (vesicant risk)
Continuous ECG & BP monitoring
Titrate to MAP ≥ 65 mmHg
Assess distal perfusion, UOP, neuro status
NEVER stop abruptly → rebound hypotension/shock
7. Math & Calculations
Most vasopressors: mcg/kg/min
Pre-mixed IV bags
Pumps programmed, but double-check!
Example #1: Dopamine
Order: 5 mcg/kg/min
Supply: 400 mg in 250 mL D5W
Weight: 63 kg
Answer: 11.8 mL/hr
Example #2: Norepinephrine
Order: 0.07 mcg/kg/min
Supply: 4 mg in 250 mL D5W
Weight: 102 kg
Answer: via calc methods (dimensional/order over supply)
🧠 Memory Aids
“ABC”: Alpha = BP ↑ (vasoconstriction), Beta-1 = Beats ↑, Beta-2 = Bronchi relax
Norepinephrine = “Levophed → leave them dead” (severe vasoconstriction, ischemia risk if extravasation)
Epinephrine = “Everything ↑” (HR, BP, bronchi open)
Vasopressin = “Vessel squeeze + water in”
Dopamine = “Dose-dependent”: Low → kidney, Medium → heart, High → vessels