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Vasopressors & Inotropes

Dobutamine CRI

Inotrope CRI for dogs and cats. Used short-term to augment forward flow in low cardiac output and acute heart failure (MMVD stage C and D), and to support cardiac output during general anesthesia. Reach for it once fluid resuscitation is complete and the goal is contractility, not vasoconstriction.

Stock: 12.5 mg/mL (12 500 µg/mL)
How this calculator works

Enter the patient's weight and dose. The calculator picks a bag concentration matched to the patient's size, and offers two containers: a 50 mL syringe (for syringe-pump precision) or a 250 mL bag (for the standard volumetric-pump workflow).

Both selections show 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.

If the resulting pump rate falls below the volumetric precision floor (≈ 2 mL/hr at small patient + low dose), run the 50 mL syringe in a syringe pump for accurate delivery.

Dogs: 2.0–20.0 · Cats: 1.0–5.0 ug/kg/min
50 mL preparation
Draw 1 mL of 12.5 mg/mL dobutamine stock (0.05 of a vial; discard the rest = 12 mg)
Add to 50 mL bag of 5% dextrose, 0.9% NaCl, or LRS
Final 250 µg/mL dobutamine in 50 mL
250 mL preparation
Draw 5 mL of 12.5 mg/mL dobutamine stock (quarter-vial; discard the rest = 62 mg)
Add to 250 mL bag of 5% dextrose, 0.9% NaCl, or LRS
Final 250 µg/mL dobutamine in 250 mL
50 mL preparation
Draw 2 mL of 12.5 mg/mL dobutamine stock (0.10 of a vial; discard the rest = 25 mg)
Add to 50 mL bag of 5% dextrose, 0.9% NaCl, or LRS
Final 500 µg/mL dobutamine in 50 mL
250 mL preparation
Draw 10 mL of 12.5 mg/mL dobutamine stock (half-vial; discard the rest = 125 mg)
Add to 250 mL bag of 5% dextrose, 0.9% NaCl, or LRS
Final 500 µg/mL dobutamine in 250 mL
50 mL preparation
Draw 4 mL of 12.5 mg/mL dobutamine stock (0.20 of a vial; discard the rest = 50 mg)
Add to 50 mL bag of 5% dextrose, 0.9% NaCl, or LRS
Final 1000 µg/mL dobutamine in 50 mL
250 mL preparation suggested · uses one full vial
Draw 20 mL of 12.5 mg/mL dobutamine stock (1 vial = 250 mg)
Add to 250 mL bag of 5% dextrose, 0.9% NaCl, or LRS
Final 1000 µg/mL dobutamine in 250 mL
Awaiting input

Enter a patient weight to see the result.

Reference

How the calculation works

Dobutamine 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
250 µg/mL 1 mL stock into 49 mL carrier fluid Very small patients (<5 kg)
500 µg/mL 2 mL stock into 48 mL carrier fluid Most cats, small/medium dogs (5–15 kg)
1000 µg/mL 4 mL stock into 46 mL carrier fluid Medium/large dogs (>15 kg)
12500 µg/mL Undiluted vial Too concentrated for accurate syringe-pump dosing
Dilution helper — Dobutamine CRI

Work out how many mL of stock drug and diluent to combine for any target concentration. Stock is pre-filled for Dobutamine 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.