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Mixing instructions and dosing for push dose epinephrine and phenylephrine for acute hypotension
Patient with acute hypotension (SBP <90 mmHg) requiring immediate intervention
Target MAP: ≥65 mmHg
Interval: Every 2-5 minutes as needed
Use as: Bridge therapy only
Prepare: Continuous infusion if >3 doses needed
Continuous cardiac monitoring
Frequent blood pressure checks (every 1-2 min)
Watch for tachycardia, arrhythmias
Watch for hypertensive emergency
Prepare for continuous infusion if multiple doses needed
Important Note: Bridge therapy while establishing continuous vasopressor infusion. Do NOT confuse with code-dose epinephrine (1 mg).
| Feature | Epinephrine | Phenylephrine |
|---|---|---|
| Mechanism | Alpha + Beta | Pure Alpha |
| Heart Rate | Increases (β1) | Reflex bradycardia |
| Contractility | Increases (β1) | No effect |
| SVR | Increases (α1) | Increases (α1) |
| Duration | 5-10 min | 15-20 min |
| Best For | Bradycardia + hypotension | Spinal/epidural hypotension |
| Arrhythmia Risk | Higher | Lower |
Code dose = 1 mg (1,000 mcg)
Push dose = 10-20 mcg
100x difference! Can be fatal.
Must dilute correctly. Never give undiluted phenylephrine or concentrated epinephrine as push dose.
Push dose pressors are temporary bridge therapy. Prepare continuous infusion if multiple doses needed.
Must have continuous cardiac monitoring and frequent BP checks. Can cause dangerous arrhythmias or hypertension.
Push dose pressors are ideal for acute, transient hypotension that requires immediate treatment but doesn't justify a continuous infusion. Common scenarios: post-induction hypotension, neuraxial anesthesia hypotension, awaiting vasopressor infusion setup. They are bridge therapy, not definitive management.
If requiring more than 2-3 push doses, start a continuous vasopressor infusion (norepinephrine preferred for most shock states). Don't rely on repeated push doses for sustained hypotension. Calculate total dose given and use to guide initial infusion rate (e.g., if giving push dose epi 20 mcg q3min = approximately 0.05-0.1 mcg/kg/min infusion).
Phenylephrine: Pure vasoconstriction, good for spinal/epidural hypotension or high cardiac output states. May cause reflex bradycardia (not necessarily bad). Epinephrine: Combined inotrope and vasopressor, good for low cardiac output or bradycardia with hypotension. More arrhythmogenic. Consider patient's heart rate and cardiac function.
Ephedrine (5-10 mg IV push) is another option for acute hypotension, especially with bradycardia. Indirect sympathomimetic with alpha and beta effects. Longer duration (15-60 min) than push dose pressors. Preferred by some anesthesiologists for obstetric hypotension. Tachyphylaxis can develop with repeated doses.
Push dose epinephrine is diluted to 10 mcg/mL and given in 5-20 mcg doses for acute hypotension in a patient WITH A PULSE. Code dose epinephrine is 1 mg (1,000 mcg) given during cardiac arrest (no pulse). The code dose is 50-200 times larger than a push dose. Never confuse these - giving code dose to a patient with a pulse can be fatal.
Use cardiac epinephrine 1:10,000 (1 mg in 10 mL = 0.1 mg/mL). Take 1 mL and add 9 mL NS to make 10 mL total (0.01 mg/mL = 10 mcg/mL). Label the syringe clearly. Store away from code cart epinephrine. Some institutions use pre-filled syringes to reduce errors. Double-check concentration before every dose.
Choose epinephrine if: Patient is bradycardic, low cardiac output suspected, need both inotropy and vasoconstriction. Choose phenylephrine if: Patient is tachycardic, pure vasoplegia (spinal/epidural), want to avoid tachycardia/arrhythmia. Phenylephrine has no beta effects so won't increase heart rate or contractility.
Yes, push dose pressors can be given through peripheral IV. However, ensure good IV access and flush well. If extravasation occurs, both epinephrine and phenylephrine can cause tissue necrosis. If possible, use large-bore peripheral IV in large vein or central line. Never give through small hand IVs if avoidable.
If you need more than 2-3 push doses (within 10-15 minutes), start a continuous vasopressor infusion. Repeated push doses indicate sustained hypotension requiring continuous therapy. Norepinephrine is preferred first-line vasopressor for most shock states. Push dose pressors are meant as bridge therapy while establishing infusion.
Risks include: Hypertensive emergency from excessive dose, tachycardia and arrhythmias (especially epinephrine), myocardial ischemia in CAD patients, tissue necrosis from extravasation, medication errors (confusing with code dose), reflex bradycardia (phenylephrine). Use lowest effective dose, monitor closely, and have atropine/esmolol available for bradycardia/tachycardia.
This push dose pressor calculator is for educational and reference purposes only. It is designed for use by healthcare professionals trained in hemodynamic management and vasopressor administration. Push dose pressors are potent medications that require careful preparation, dosing, and monitoring. Medication errors can be life-threatening. This tool does not replace clinical judgment, formal training, or institutional protocols. Always verify concentrations, use proper labeling, and follow safety protocols. Use only as bridge therapy for acute hypotension while preparing definitive management.