InfusionFox
Vasopressors & Inotropes

Epinephrine CRI

Vasopressor CRI for dogs and cats. Reserved for hypotension that has not responded to fluid resuscitation, an inotrope, or a more selective vasopressor; positioned as a second-line vasopressor in vasodilatory shock after norepinephrine. Drives more tachycardia and myocardial oxygen demand than norepinephrine. Use the lowest effective dose and titrate down as the patient tolerates.

Stock: 1 mg/mL (1000 µg/mL), formerly labeled 1:1000
How this calculator works

Enter the patient's weight and dose. The calculator picks a syringe concentration matched to the patient's size: 20 µg/mL for very small patients, 40 µg/mL for most cats and small/medium dogs, 80 µg/mL for larger dogs. Each preparation is the same 50 mL syringe volume, with the drug load scaled to fit a syringe-pump infusion.

The concentration tab shows a suggested tag that updates as you change the patient inputs. Click any tab to override; the override sticks for the rest of the session.

For very small patients or very low doses where even the most dilute preparation gives an unworkable pump rate, switch to Advanced: target pump rate; you pick the rate you want, the calculator derives the syringe concentration to deliver it.

Typical range: 0.05–2.0 ug/kg/min (dogs and cats)
50 mL preparation
Draw 1 mL of 1 mg/mL epinephrine stock (1 vial = 1 mg)
Add to 50 mL bag of 0.9% NaCl or 5% dextrose
Final 20 µg/mL epinephrine in 50 mL
50 mL preparation
Draw 2 mL of 1 mg/mL epinephrine stock (2 vials = 2 mg)
Add to 50 mL bag of 0.9% NaCl or 5% dextrose
Final 40 µg/mL epinephrine in 50 mL
50 mL preparation
Draw 4 mL of 1 mg/mL epinephrine stock (4 vials = 4 mg)
Add to 50 mL bag of 0.9% NaCl or 5% dextrose
Final 80 µg/mL epinephrine in 50 mL
Awaiting input

Enter a patient weight to see the result.

Reference

How the calculation works

Epinephrine CRI is dosed in µg/kg/min. To convert a per-minute dose into a per-hour CRI rate, multiply by 60. The full formula:

$$\text{mL/hr} = \frac{\text{weight}_{\text{kg}} \times \text{dose}_{\mu g/kg/min} \times 60}{\text{concentration}_{\mu g/mL}}$$

Why the 60? The patient's weight (kg) times the dose (µg per kg per minute) gives micrograms per minute. Multiplying by 60 converts to micrograms per hour. Dividing by the concentration (µg per mL of the prepared CRI) yields mL per hour.

In target-pump-rate mode the pump rate is fixed by the clinician and the bag concentration is the unknown. The preparation runs in three steps.

Step 1: bag concentration

Same numerator as standard-bag mode (the total drug delivered per hour for this patient), but divided by the chosen pump rate instead of by a chosen bag concentration:

$$\text{bag concentration}_{\mu g/mL} = \frac{\text{weight}_{\text{kg}} \times \text{dose}_{\mu g/kg/min} \times 60}{\text{pump rate}_{\text{mL/hr}}}$$

Step 2: total drug in the bag

The bag concentration times the chosen bag volume gives the total micrograms of drug to add. Convert to milligrams (divide by 1,000) for the size of stock you'll actually be drawing:

$$\text{total drug}_{\mu g} = \text{bag concentration}_{\mu g/mL} \times \text{bag volume}_{\text{mL}}$$
$$\text{total drug}_{mg} = \frac{\text{total drug}_{\mu g}}{1{,}000}$$

Step 3: volume of stock to draw

Total drug divided by the stock vial concentration gives the volume of stock to draw and add to the bag:

$$\text{stock volume}_{\text{mL}} = \frac{\text{total drug}_{mg}}{\text{stock}_{mg/mL}}$$

Worked through together: divide the total drug in the bag by the stock vial's mg/mL to get the mL of stock that contains that much drug. That is the volume to pull into the syringe and add to the bag.

Worked example with current inputs

Enter a patient weight to see the worked example.

Reference

Recommended dilutions

Target concentration Dilution When useful
20 µg/mL 1 mL stock in 49 mL carrier fluid Very small patients (<5 kg)
40 µg/mL 2 mL stock in 48 mL carrier fluid Most cats, small/medium dogs (5–20 kg)
80 µg/mL 4 mL stock in 46 mL carrier fluid Larger dogs (>20 kg)
1000 µg/mL Undiluted vial (1 mg/mL stock, the CRI strength, formerly 1:1000) Too concentrated for accurate syringe-pump dosing, always dilute

Use the 1 mg/mL ('1:1000') strength for CRI dilution, NOT the 0.1 mg/mL ('1:10,000') strength which is the cardiac-arrest bolus formulation. Most balanced isotonic crystalloids (0.9% NaCl, LRS, Ringer's) work as carrier fluids, as does 5% dextrose; however, epinephrine becomes unstable in 5% dextrose at pH > 5.5, so for prolonged infusions check the solution color before and during use. Discard any solution that turns pink, brown, or develops a precipitate. Do not mix epinephrine with sodium bicarbonate or other alkalinizing solutions, and do not co-administer in a line containing oxidizing agents: the catecholamine is rapidly destroyed in those conditions.

Dilution helper — Epinephrine CRI

Work out how many mL of stock drug and diluent to combine for any target concentration. Stock is pre-filled for Epinephrine CRI; change it if you're using a different vial.

Suggestions from the reference table above
Draw up

Enter stock, target concentration, and final volume.