An induction agent (e.g. propofol) induces a state of immediate unresponsiveness. This is then followed by the administration of a neuromuscular blocking agent to induce paralysis. The combination of drugs ceases spontaneous ventilation in the patient and allows for better view of the vocal cords. RSI is useful in patients with an intact gag reflex, a full stomach and a life threatening injury or illness requiring immediate airway control.
There are considerable variations in medications used for induction and paralysis. In the UK, propofol and ketamine remain the two most commonly used induction agents. There is now a shift of use of paralytic agent, from suxamethonium to rocuronium. In a recent analysis of 4275 intubations performed in the ED (USA), suxamethonium and rocuronium exhibited no differences in first-pass success (87.0% versus 87.5%) or adverse events (14.7% versus 14.8%) (April MD et al). This study only examined patients receiving either suxamethonium or rocuronium.
The most common induction agents used are:
| Drug | How to make up | Final concentration |
| Propofol 1% | Neat – into 20ml syringe | 10mg/ml |
| Ketamine 500mg/10ml | Neat – into 10ml syringe | 50mg/ml |
| Thiopentone 500mg vial | Add 20ml water into 20ml syringe | 25mg/ml |
| Etomidate 20mg/10ml | Neat – into 10ml syringe | 2mg/ml |
The most common paralysing agents used are:
| Drug | How to make up | Final concentration |
| Suxamethonium 50mg/ml | Neat – 1 ampoule into 2ml syringe | 50mg/ml |
| Rocuronium 50mg/5ml | Neat – 2 ampoules into 10ml syringe | 10mg/ml |
| Atracurium 50mg/5ml | Neat – 2 ampoules into 10ml syringe | 10mg/ml |
| Vecuronium 10 mg | Add 5ml water into 5ml syringe | 2mg/ml |