Calculation Guide

Part A: Calculating Patient Dose

Use this when checking a running pump to see how much drug the patient is receiving.

1 Calculate Concentration

Determine how much drug is in every milliliter.

Conc (mg/ml) = Total Drug Amount (mg) Total Syringe Volume (ml)

2 Calculate Hourly Dose

Multiply concentration by the running rate.

Dose/hr = Conc × Rate (ml/hr)

3 Calculate 24-Hour Dose

Project the dose over a full day.

Dose/24hr = Dose/hr × 24

4 Duration Safety Check

Ensure the syringe volume is sufficient.

Duration = Total Volume (ml) Rate (ml/hr)

⚠️ If Duration < 24 hours, the pump will empty early.

Part B: Preparing a Syringe

Use this when mixing a new syringe to determine volumes and diluent needed.

1 Calculate Drug Volumes

Convert the required dose (mg) into volume (ml) using standard concentrations.

Drug Vol (ml) = Prescribed Dose Concentration
Morphine10 mg/ml
Fentanyl50 mcg/ml
Hyoscine20 mg/ml
Midazolam5 mg/ml (or 1mg/ml)
Levomepromazine25 mg/ml

2 Total Drug Volume

Add the volume of every drug being added to the syringe.

Total Drug Vol = Vol A + Vol B + Vol C...

3 Calculate Diluent

Determine how much saline/water to add to reach the target syringe size (e.g., 22ml).

Diluent = Target Volume - Total Drug Vol

⚠️ If Total Drug Vol > Target Volume, you need a larger syringe or more concentrated drugs.

4 Set Infusion Rate

Calculate the rate to run the syringe over 24 hours.

Rate (ml/hr) = Target Volume (ml) 24 hours

Example: 22ml ÷ 24hr ≈ 0.92 ml/hr

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