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Vasopressors & Inotropes

Dopamine CRI · standard method

Catecholamine CRI for dogs and cats with dose-dependent receptor activity (β₁ inotropy at mid doses, α₁ vasoconstriction at higher doses). Used for hypotension and shock where both inotropic and vasopressor support are needed. Above 20 µg/kg/min, switch to norepinephrine for a more selective vasopressor effect.

Stock: 40 mg/mL (40 000 µg/mL)
Standard CRI workflow

This is the standard CRI calculator for dopamine, works with any bag size. If you have a 100 mL bag available, the 6×kg method → is simpler (the pump rate equals the dose in µg/kg/min, no further math at the bedside).

How this calculator works

Two standard preparations, both using a 200 mg load (5 mL of 40 mg/mL stock). The 250 mL bag gives 800 µg/mL; the 500 mL bag gives 400 µg/mL. Both deliver the same dose at the same pump rate; the choice is workflow-driven, not patient-driven.

The suggested tag on the bag size follows your concentration choice; each concentration has a matching bag that uses one full 200 mg vial. The off-diagonal combinations (e.g. 400 µg/mL in a 250 mL bag) are still valid; the suggested tag points to the standard preparation for each concentration.

For very small patients where even the more dilute 400 µg/mL preparation gives a pump rate below 2 mL/hr, switch to Advanced: target pump rate; you pick the rate you want, the calculator derives the bag concentration to deliver it.

Dogs: 3.0–20.0 · Cats: 5.0–20.0 ug/kg/min
250 mL preparation suggested · uses one full vial
Draw 5 mL of 40 mg/mL dopamine stock (1 vial = 200 mg)
Add to 250 mL bag of 0.9% NaCl or 5% dextrose
Final 800 µg/mL dopamine in 250 mL
500 mL preparation
Draw 10 mL of 40 mg/mL dopamine stock (2 vials = 400 mg)
Add to 500 mL bag of 0.9% NaCl or 5% dextrose
Final 800 µg/mL dopamine in 500 mL
250 mL preparation
Draw 2.5 mL of 40 mg/mL dopamine stock (half-vial; discard the rest = 100 mg)
Add to 250 mL bag of 0.9% NaCl or 5% dextrose
Final 400 µg/mL dopamine in 250 mL
500 mL preparation suggested · uses one full vial
Draw 5 mL of 40 mg/mL dopamine stock (1 vial = 200 mg)
Add to 500 mL bag of 0.9% NaCl or 5% dextrose
Final 400 µg/mL dopamine in 500 mL
Awaiting input

Enter a patient weight to see the result.

Reference

How the calculation works

Dopamine CRI · standard method 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
800 µg/mL 200 mg (5 mL of 40 mg/mL) into a 250 mL bag of 0.9% NaCl or 5% dextrose 250 mL bag prep
400 µg/mL 200 mg (5 mL of 40 mg/mL) into a 500 mL bag of 0.9% NaCl or 5% dextrose 500 mL bag prep

Standard CRI preparation. Dopamine is compatible with 0.9% NaCl, 5% dextrose, LRS, and Ringer's. Plumb's hard ceiling for the compounded final concentration is 3200 µg/mL (3.2 mg/mL); both preset preparations above are well under this limit. Discard if the solution turns pink, yellow, or brown; these indicate oxidative degradation. Dopamine is incompatible with sodium bicarbonate and other alkaline solutions; do not co-administer in the same line. For the 100 mL bag Plumb's 6×kg method, see the dopamine 6×kg calculator (it gives the same drug delivery with the elegant identity that pump rate equals dose).

Dilution helper — Dopamine CRI · standard method

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

Suggestions from the reference table above
Draw up

Enter stock, target concentration, and final volume.