LA Safe Dose — Local Anaesthetic Safe Dose Calculator

Cumulative Toxic Fraction (CTF) model — each entered volume contributes its fractional maximum additively across all agents.

User input

Full CTF available

Remaining allowance (CTF reduced)

CTF exhausted / dose exceeded

Manually entered volume

IBW override

Patient Addressograph — a labelled sticker placeholder appears top-right on the printed A4 sheet.

Patient Demographics

Height (cm)

Enter patient height in centimetres

Weight (kg)

Fallback if IBW cannot be calculated

Sex

Required for Devine formula

Calculated IBW (kg)

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Devine: Male = 50 + 0.906 × (cm − 152.4) · Female = 45.5 + 0.906 × (cm − 152.4)

IBW Override (kg)

Enter known IBW to override the calculated value

IBW Used (kg) ← drives all calculations

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Override › Calculated IBW › Actual weight

⚖ Cumulative Toxic Fraction (CTF) Used: 0.0% | Remaining: 100.0%

Enter patient details and volumes to see CTF breakdown

Maximum Dose Table — Remaining Allowance updates live as CTF is consumed

Drug	Conc.	mg/kg limit	Absolute Max (mg)	Absolute Max (mL)	Remaining Allowance (mL)	Enter Volume (mL)	% of this drug's max

* Absolute ceiling applies regardless of weight — Lidocaine 200 mg · Lidocaine + Adrenaline 500 mg · Bupivacaine 150 mg · Prilocaine 400 mg. The lower of weight-based dose and ceiling is used.

Cumulative Toxic Fraction (CTF): Each entered volume is expressed as a fraction of that drug’s absolute maximum. The CTF is the sum of all fractions across every agent — e.g. 50% lidocaine + 30% bupivacaine = CTF 0.80, leaving 20% of the combined toxic threshold. The Remaining Allowance column reflects this live for every row. Clinical judgement must always be applied.

Disclaimer & Legal Notice

Clinical Use: LA Safe Dose is a decision-support tool for qualified healthcare professionals. It does not replace clinical judgement, formal training, or institutional protocols. All dose calculations must be independently verified before administration. The authors accept no liability for clinical decisions made on the basis of this tool.

Dose Limits: Maximum doses are derived from the AAGBI Guidelines on Local Anaesthesia and the British National Formulary (BNF). Where a weight-based dose exceeds the absolute ceiling (Bupivacaine 150 mg, Lidocaine 200 mg, Lidocaine with Adrenaline 500 mg, Prilocaine 400 mg), the lower ceiling applies. Ropivacaine is weight-based only. These are conservative upper limits; clinical context must always be considered.

Accuracy: Drug doses and guidelines are subject to change. Users are responsible for checking current approved product information and local guidelines.