InfusionFox
Cardiology

Furosemide CRI

Refractory congestive heart failure (MMVD stage D, end-stage DCM, refractory pulmonary edema), acute fulminant pulmonary edema unresponsive to bolus diuretic therapy, oliguric or anuric acute kidney injury (in select protocols, with appropriate volume status), and volume management in life-threatening hyperkalemia. CRI delivery is preferred over repeated bolus for severe or refractory cases: smoother diuresis, less ototoxicity, better natriuretic efficiency. Continuous monitoring required: serum electrolytes, creatinine/BUN, body weight, urine output, blood pressure.

Stock: 50 mg/mL (50 000 µg/mL), 50 mL multi-dose vial (2 500 mg per vial)
How this calculator works

Enter the patient's weight and the desired CRI dose. The calculator picks a concentration (5, 2, or 1 mg/mL) that keeps the pump in its accurate range.

Cat doses run lower than dogs (0.25–1 vs 0.25–2 mg/kg/hr), and the cat-specific caution threshold is correspondingly lower; cats are more prone to dehydration and electrolyte derangements at any given diuretic dose.

Loading dose (1–4 mg/kg IV over 1–2 minutes) is shown above the CRI maintenance rate. Drive the initial diuresis with the loading bolus; the CRI maintains response with a smoother curve and less ototoxicity than repeated bolus dosing.

Dogs: 0.25–2.0 · Cats: 0.25–1.0 mg/kg/hr
2000 µg/mL
2 mL of 50 mg/mL stock (100 mg total) into 48 mL of 0.9% NaCl in a 50 mL syringe (final volume 50 mL)
Use a different concentration

All preparations are pharmacologically equivalent. The default (2000 µg/mL) fits the most common clinical use case. The alternatives below cover situational needs.

Awaiting input

Enter a patient weight to see the result.

Reference

How the calculation works

Furosemide CRI is dosed in mg/kg/hr. Because the prepared CRI concentration is expressed in µg/mL, the formula needs a × 1000 to convert the mg dose into µg before dividing:

$$\text{mL/hr} = \frac{\text{weight}_{\text{kg}} \times \text{dose}_{mg/kg/hr} \times 1000}{\text{concentration}_{\mu g/mL}}$$

Patient weight (kg) times dose (mg per kg per hour) gives mg per hour. Multiplying by 1,000 converts mg to µg so the units match the bag concentration. Dividing by µg/mL 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:

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

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
5000 µg/mL 5 mL of 50 mg/mL stock (250 mg total) into 45 mL of 0.9% NaCl in a 50 mL syringe (final volume 50 mL) Recommended for patients ≥15 kg. Concentrated end of the range, minimizes carrier-fluid load in volume-restricted patients with CHF.
2000 µg/mL 2 mL of 50 mg/mL stock (100 mg total) into 48 mL of 0.9% NaCl in a 50 mL syringe (final volume 50 mL) Standard preparation for patients 5–15 kg. Matches the most common ICU CHF workflow.
1000 µg/mL 1 mL of 50 mg/mL stock (50 mg total) into 49 mL of 0.9% NaCl in a 50 mL syringe (final volume 50 mL) Dilute preparation for patients <5 kg (cats and small dogs). Essential when more concentrated preps would drop pump rate below 2 mL/hr at conservative cat doses.

Stock: 50 mg/mL injectable, 50 mL multi-dose vial (2 500 mg per vial). For CRI: 0.9% NaCl is the preferred diluent. 5% dextrose is borderline; some references list mild incompatibility; if D5W must be used, prepare fresh and deliver promptly. Furosemide is sensitive to acidic conditions; precipitates in lactated Ringer's and most acidic IV fluids. Avoid mixing in the same line with calcium-containing solutions, epinephrine, or any acidic drug. Light-protection: not strictly required for short-term infusions, but discard the prepared syringe if any color change to yellow or amber appears; furosemide degrades in ambient light over hours, particularly when exposed at elevated temperature. Companion medications: pair the CRI with electrolyte monitoring at 4–6 hour intervals. Hypokalemia frequently develops within the first 12 hours and is best managed preemptively with potassium-containing IV fluid or potassium supplementation rather than waiting for severe derangement.

Dilution helper — Furosemide CRI

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