Rapid sequence induction (RSI) is primarily used for induction in patients with risk of aspiration, such as those who are non-fasted and require urgent surgery. The alternative term is rapid sequence intubation, conveniently using the same acronym: they are the same thing.
It differs from a standard induction in the rapidity of intubation. The goal is to leave the airway unprotected for the minimum possible time. Preoxygenation is completed prior to the start of the procedure and then induction and paralysis are rendered one after the other. Immediately thereafter an endotracheal airway is secured.
The RSI procedure
- Prepare for a surgical airway. Just in case.
- Asses the airway.
- Sucker ready, ventilator ready.
- Tube ready, scope ready
- Position yourself, position everyone else
- Pre-ox, pre-load, (pre-medicate)
- Drugs
- Cricoid pressure…
- Induce
- Paralyse
- Intubate, auscultate, ventilate
- ETCO
Induction agents
Now that barbiturates are in the bin, the below three agents are all that most people use routinely. Propofol has a propensity to drop the blood pressure and etomidate or ketamine may be better suited to the hypotensive (or potentially hypotensive patient). Ketamine causes myocardial depression but also increases sympathetic tone: in patients with inadequate sympathetic reserve it may well tank the blood pressure.
Propofol
RSI dosing: 2mg/kg, unless increased risk of hypotension. Onset: 30-45s Duration of action: 5-10mins
Etomidate
RSI dosing: 0.2-0.4mg/kg Onset: 30-45s Duration of action: 5-15mins
Adrenal suppression
There is a non-zero risk of adrenal suppression with etomidate administration though the evidence is not really convincing enough to impact practice… It should probably be avoided in florid sepsis.
Ketamine
RSI dosing: 1-2mg/kg(idea body weight) Onset: 30s Duration of action: 5-10mins
Paralytics
Neuromuscular blockade makes for more favourable intubating conditions. The ideal agent has a rapid onset, short duration of action, and no significant side effects. Suxamethonium chloride, the only remaining depolarising paralytic in clinical use, is probably the best agent available.
Succinylcholine
RSI dosing: 1-2mg/kg Onset: 30-60s Duration of action: 5-10mins
Risk of hyperkalaemia
Sux regularly causes a non-trivial rise in the serum potassium. It should be avoided in patients with hyperkalaemia, particularly those with ECG changes, and in those at risk of hyperkalaemia such as burn victims (particularly between 24-72hours post injury).
Sux has the fastest onset, and because it is a depolarising agent, it comes with a helpful indicator to intubate: when the patient’s fasciculations stop. Probably to the dismay of Professor Lee, it is now in its eighth decade and still hasn’t been abandoned. 1
Rocuronium
RSI dosing: 1mg/kg Onset: 60s Duration of action: 30-60mins (reversible with sugammadex)
Vecuronium…
2 minutes to paralysis is suboptimal. Go looking elsewhere if you really need to use this.
Footnotes
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Lee C. Goodbye Suxamethonium! Anaesthesia. 2009 Mar;64(s1):73–81. ↩