Gas Cookbook | Calculator changelog

14 Oct 2026

Opioid Conversion

v0.4.0Major

IV/SC morphine is half the oral dose (MST Continus SPC, NHS Scotland); was a third.
IV/SC oxycodone equals IV morphine (factor 2, was 4) and oral to IV oxycodone is 2:1, as in the OxyNorm injection SPC.
Fentanyl (0.2, was 0.3) and pethidine (0.25, was 0.375) factors change to keep their anchors to IV morphine: 100 mcg fentanyl ≈ 10 mg IV morphine; 100 mg pethidine ≈ 12.5 mg IV morphine.

61/61 checks run and passed

Reviewed by JC

Lean / Ideal / Adjusted Body Weight

v0.2.0Major

Drug weight bases follow the Association of Anaesthetists / SOBA 2015 table: lean body weight for fentanyl, morphine, rocuronium, vecuronium, atracurium, paracetamol, lidocaine and bupivacaine; adjusted body weight for alfentanil and neostigmine (max 5 mg).
Ideal body weight uses Devine's 2.3 kg per inch exactly (was up to 0.4 kg out at extreme heights; 0.1 kg at 178 cm).

79/79 checks run and passed

Reviewed by JC

Paediatric Anaesthesia

v2.0.0Baseline

Version 2.0.0: doses, maximums and sections checked against UK product licences and guidelines (RCUK 2025, Embrace, NHS GGC, BSH). Later changes are listed here.

329/329 checks run and passed

Reviewed by JC

Opioid Conversion

v0.4.0Major

IV/SC morphine is half the oral dose (MST Continus SPC, NHS Scotland); was a third.
IV/SC oxycodone equals IV morphine (factor 2, was 4) and oral to IV oxycodone is 2:1, as in the OxyNorm injection SPC.
Fentanyl (0.2, was 0.3) and pethidine (0.25, was 0.375) factors change to keep their anchors to IV morphine: 100 mcg fentanyl ≈ 10 mg IV morphine; 100 mg pethidine ≈ 12.5 mg IV morphine.

61/61 checks run and passed

Reviewed by JC

Lean / Ideal / Adjusted Body Weight

v0.2.0Major

Drug weight bases follow the Association of Anaesthetists / SOBA 2015 table: lean body weight for fentanyl, morphine, rocuronium, vecuronium, atracurium, paracetamol, lidocaine and bupivacaine; adjusted body weight for alfentanil and neostigmine (max 5 mg).
Ideal body weight uses Devine's 2.3 kg per inch exactly (was up to 0.4 kg out at extreme heights; 0.1 kg at 178 cm).

79/79 checks run and passed

Reviewed by JC

Paediatric Anaesthesia

v2.0.0Baseline

Version 2.0.0: doses, maximums and sections checked against UK product licences and guidelines (RCUK 2025, Embrace, NHS GGC, BSH). Later changes are listed here.

329/329 checks run and passed

Reviewed by JC