2006B04 Describe the advantages and disadvantages of rocuronium for rapid sequence induction.

· Intro: rapid sequence introduction

· Ideal kinetics

· Ideal dynamics

Rapid sequence induction

· What: minimise time between hypnosis and intubation

· Why: reduced risk of aspiration if

o Recent meal

o Impaired gastric emptying

o Otherwise at risk of regurgitation

· How:

o Rapid hypnotic (thiopentone – highly lipid soluble)

o Rapid relaxant (suxamethonium classically)

o Pre-oxygenate

o Cricoid pressure

o Suction ready

Rocuronium

· Fast onset non-depolarising neuromuscular blocker

· Used in modified RSI

· Large dose produces onset time similar to suxamethonium, but at the expense of long duration

	Rocuronium (ROC)	Suxamethonium (SUX) or other
Cheap	$20	$2
Compatibile with induction drugs	Thio (pH 11) + roc (pH 3.5) -> precipitation	pH 3.5 -> same
Doesn’t need refrigeration	Does	Does
Long life at room temp (90% potency)	2/12	2/52
Doesn’t need reconstitution	Doesn’t	Doesn’t (Vecuronium does)

	Rocuronium	Suxamethonium or other
Admin:
Can maintain paralysis by infusion	Y (but prolonged effect)	No (phase 2 blockade) (Gantacurium: Y (fast offset))
Can give IM if IV cannula fails	No	Yes
Time course:
Rapid onset intubating conditions (Bowman principle: ↓potency -> ↑speed)	2x ED₉₅ = 0.6mg/kg: 1-1.5min 4xED₉₅ = 1.2mg/kg: 0.75-1min	4xED₉₅ = 1.2 mg/kg: 0.5-1min
Rapid offset TOF 0.9 -Quick wake up after short procedure -Safer if CICO	2xED₉₅: 30-40mins 4xED₉₅: 45-60 mins	4xED₉₅: 5 mins (Gantacurium 10 mins max)
Absorption	N/A
Distribution:
-Rapid distribution i.e. fast offset after single bolus (e.g. gastroscopy)	Fast?	Fast?
-V_DSS
Metabolism/excretion
-Rapid metabolism i.e. fast offset after long infusion	t_1/2_β 70 mins (slow)	t_1/2_β 1-2 mins (fast)
-Organ-independent metabolism (ok if liver/kidney failure)	5% metabolized 60% bile excretion 35% renal excretion	Plasma cholinesterase (produced by liver but rarely affected by liver disease) (Gantacurium: cysteine adduction)
-No active metabolites (ok if liver/kidney failure)	17-desacetylrocuronium less active Hepatic elimination	Nil (Gantacurium: Nil)
-No significant polymorphism		Sux apnoea rare (pseudocholinesterase polymorphism)

	Rocuronium	Suxamethonium or other
Effect:
-Non-depolarising	√	Depolarizing (ion flux -> ↑plasma K⁺)
-No desensitisation	√	Y (Phase 2 blockade, prolonged)
-Antidote for deep blockade i.e. fast offset after short case i.e. Safer if CICO	γ-cyclodextrin 16mg/kg if CICO	N

Side effects:
No histamine release	Does not	Does
No anaphylaxis	1 in 2500	1 in 2000 (Gantacurium: very low)
No ↑K⁺	√	Y (depolarisation) ↑↑↑ if denervated e.g. burns
No cardiac mAChr effect	√	Agonist -> sinus bradycardia, AV block, asystole, esp children
No malignant hyperthermia	√	Does (activate abnormal ryanodine receptor)
No myalgia	√	√ (depolarisation)
No ↑IOP	√	√ (depolarisation)
No ↑IGP	√	√ (depolarisation) ↑risk aspiration (but also ↑lower oesophageal sphincter pressure)
No ganglion blockade	√	dTC does