InfusionFox
Cardiology

Nitroprusside CRI

Mixed arterial / venous vasodilator for hypertensive emergencies (pheochromocytoma crisis, acute severe hypertension), heart failure with afterload reduction need (MMVD stage D refractory CHF, dilated cardiomyopathy), perioperative BP control in cardiac surgery, and anesthesia-induced hypertension. Continuous BP monitoring required, with arterial line preferred. Limit total infusion duration to minimize cyanide accumulation risk.

Stock: 50 mg lyophilized vial; reconstitute with 2 mL D5W to 25 mg/mL working stock
How this calculator works

Enter the patient's weight and dose. The calculator picks a bag concentration that keeps the pump in its accurate range (≥ 2 mL/hr for most volumetric pumps), and a bag size that uses one full 50 mg vial of stock.

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, and a notice will appear if your choice doesn't match the patient.

If even the most dilute preparation gives an unworkable rate (very small patient on a low dose), switch to Advanced: target pump rate; you pick the rate you want, the calculator derives the bag concentration to deliver it.

Typical range: 0.5–10.0 ug/kg/min (dogs and cats)
100 mL preparation suggested · uses one full vial
Draw 2 mL of 25 mg/mL nitroprusside stock (1 vial = 50 mg)
Add to 100 mL bag of 5% dextrose ONLY (not 0.9% NaCl)
Final 500 µg/mL nitroprusside in 100 mL
250 mL preparation
Draw 5 mL of 25 mg/mL nitroprusside stock (2.50 vials = 125 mg)
Add to 250 mL bag of 5% dextrose ONLY (not 0.9% NaCl)
Final 500 µg/mL nitroprusside in 250 mL
500 mL preparation
Draw 10 mL of 25 mg/mL nitroprusside stock (5 vials = 250 mg)
Add to 500 mL bag of 5% dextrose ONLY (not 0.9% NaCl)
Final 500 µg/mL nitroprusside in 500 mL
100 mL preparation
Draw 0.8 mL of 25 mg/mL nitroprusside stock (0.40 of a vial; discard the rest = 20 mg)
Add to 100 mL bag of 5% dextrose ONLY (not 0.9% NaCl)
Final 200 µg/mL nitroprusside in 100 mL
250 mL preparation suggested · uses one full vial
Draw 2 mL of 25 mg/mL nitroprusside stock (1 vial = 50 mg)
Add to 250 mL bag of 5% dextrose ONLY (not 0.9% NaCl)
Final 200 µg/mL nitroprusside in 250 mL
500 mL preparation
Draw 4 mL of 25 mg/mL nitroprusside stock (2 vials = 100 mg)
Add to 500 mL bag of 5% dextrose ONLY (not 0.9% NaCl)
Final 200 µg/mL nitroprusside in 500 mL
100 mL preparation
Draw 0.4 mL of 25 mg/mL nitroprusside stock (0.20 of a vial; discard the rest = 10 mg)
Add to 100 mL bag of 5% dextrose ONLY (not 0.9% NaCl)
Final 100 µg/mL nitroprusside in 100 mL
250 mL preparation
Draw 1 mL of 25 mg/mL nitroprusside stock (half-vial; discard the rest = 25 mg)
Add to 250 mL bag of 5% dextrose ONLY (not 0.9% NaCl)
Final 100 µg/mL nitroprusside in 250 mL
500 mL preparation suggested · uses one full vial
Draw 2 mL of 25 mg/mL nitroprusside stock (1 vial = 50 mg)
Add to 500 mL bag of 5% dextrose ONLY (not 0.9% NaCl)
Final 100 µg/mL nitroprusside in 500 mL
Awaiting input

Enter a patient weight to see the result.

Reference

How the calculation works

Nitroprusside 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
500 µg/mL 1 vial (50 mg, reconstituted to 25 mg/mL in 2 mL D5W) into a 100 mL bag of 5% dextrose. Foil-wrap. Concentrated preparation for patients ≥15 kg or fluid-restricted CHF cases where carrier-fluid load matters. Lowest fluid burden.
200 µg/mL 1 vial (50 mg, reconstituted to 25 mg/mL in 2 mL D5W) into a 250 mL bag of 5% dextrose. Foil-wrap. Plumb's textbook preparation ("50 mg in 250 mL D5W"). Recommended for patients 3–15 kg and most general clinical use.
100 µg/mL 1 vial (50 mg, reconstituted to 25 mg/mL in 2 mL D5W) into a 500 mL bag of 5% dextrose. Foil-wrap. Dilute preparation for patients <3 kg or any patient at very low doses where the 200 µg/mL preparation would drop pump rate below 2 mL/hr.

Reconstitution: dissolve the 50 mg lyophilized vial in 2 mL of 5% dextrose, giving a 25 mg/mL working stock. (Sterile water for injection is also acceptable for reconstitution per manufacturer; D5W is Plumb's-recommended.) Add the entire reconstituted volume to the carrier bag. Carrier fluid: 5% dextrose ONLY. Not 0.9% NaCl; Plumb's lists saline as incompatible. The same restriction applies to any line co-administering nitroprusside; if a Y-site is needed, verify compatibility per drug. Light protection is mandatory. Wrap the bag in aluminum foil or use a manufacturer-supplied opaque cover. Use opaque (amber) IV tubing where available; the in-line clear section from a standard set is acceptable since exposure is brief, but the bag itself must remain covered. Bag stability: 24 hours from reconstitution when light-protected, refrigerated or at room temperature. Discard sooner if the solution changes color; fresh nitroprusside is light brown/orange; conversion to dark brown, blue, or green indicates degradation, and the bag is no longer safe to infuse. Hospital-policy note: many institutions have specific nitroprusside compounding protocols (foil-wrap labeled with expiration time, pharmacist-prepared, double-check sign-off). Follow local protocol where it exists; treat the above as a minimum standard.

Dilution helper — Nitroprusside CRI

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