InfusionFox
Cardiology

Esmolol CRI

Ultra-short-acting β-blocker CRI for supraventricular tachyarrhythmias (SVT, atrial fibrillation / atrial flutter rate control), perioperative tachycardia or hypertension, thyrotoxic crisis (cats), and as a "trial of beta-blockade" before committing to longer-acting oral agents. Sometimes used in pheochromocytoma management AFTER alpha-blockade is established, NEVER as monotherapy. Continuous ECG, BP, and heart-rate monitoring required.

Stock: 10 mg/mL premix (10 000 µg/mL); 250 mg/mL concentrate also available; dilute to 10 mg/mL before use
How this calculator works

Enter the patient's weight and the desired CRI dose. The calculator picks a concentration (10, 5, or 2 mg/mL) that keeps the pump in its accurate range. The 10 mg/mL premix is used directly for larger patients; smaller patients get progressive dilution into a 50 mL syringe.

The recommended concentration shows a suggested tag that updates as you change the patient inputs.

Loading dose (50–500 µg/kg IV over 1 min) is shown above the CRI maintenance rate. Most of the acute hypotension risk concentrates in the loading bolus; give slowly and reassess before starting the CRI.

Typical range: 25.0–200.0 ug/kg/min (dogs and cats)
5000 µg/mL
Draw 25 mL of 10 mg/mL premix and dilute with 25 mL of 0.9% NaCl or 5% dextrose into a 50 mL syringe (1:1 dilution); deliver via syringe pump
Use a different concentration

All preparations are pharmacologically equivalent. The default (5000 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

Esmolol 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
10000 µg/mL Use the 10 mg/mL premixed bag directly via a volumetric IV pump; no dilution needed Direct use of the premixed bag for patients ≥15 kg. Lowest preparation effort; recommended when a volumetric IV pump is in use and patient size keeps pump rate in the precision range.
5000 µg/mL Draw 25 mL of 10 mg/mL premix and dilute with 25 mL of 0.9% NaCl or 5% dextrose into a 50 mL syringe (1:1 dilution); deliver via syringe pump Standard 1:1 dilution for patients 3–15 kg. Matches typical syringe-pump workflow and keeps the pump rate in the precision range for medium patients.
2000 µg/mL Draw 10 mL of 10 mg/mL premix and dilute with 40 mL of 0.9% NaCl or 5% dextrose into a 50 mL syringe (1:4 dilution); deliver via syringe pump Dilute preparation for cats and very small dogs (<3 kg) or any patient at very low doses where the 5 mg/mL preparation would drop pump rate below 2 mL/hr.

Stock: the 10 mg/mL premixed bag (Brevibloc Premixed: 100 mg/10 mL bag or 2 500 mg/250 mL bag) is the typical ICU starting point. The 250 mg/mL concentrated vial also exists but must be diluted to 10 mg/mL (or lower) before use; the manufacturer's recommended dilution is 25 mL of concentrate into 250 mL of 0.9% NaCl or 5% dextrose. Compatibility: 0.9% NaCl, 5% dextrose, and lactated Ringer's are all compatible. Avoid mixing in the same line with sodium bicarbonate (precipitation risk). Storage: refrigerate the diluted product if not used immediately; per the manufacturer, the diluted solution is stable for 24 hours at room temperature and longer refrigerated. Discard if any particulate or discoloration is visible.

Dilution helper — Esmolol CRI

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