Rapid sequence induction

Rapid sequence induction (RSI) is an advanced medical protocol of advanced airway support which permits the expeditious intubation of the trachea of a patient. It is indicated for patients who are suspected of having a full stomach, to reduce the risk of aspirating acidic stomach contents into the lungs. RSI is generally used for emergency surgery or for patients suffering major trauma or head injuries. The technique is a quicker form of the process normally used to "induce" a coma-state (anaesthesia) in preparation for elective surgery. It uses drugs to rapidly allow an endotracheal tube to be placed between the vocal cords, by blocking the patient's involuntary reflexes and muscle tone in the oropharynx. Once the endotracheal tube has been passed between the vocal cords, a cuff is inflated around the tube in the trachea and the patient can then be artificially ventilated.

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In its purest form, RSI involves pre-oxygenating the patient with a tightly-fitting oxygen mask for three minutes, followed by the sequential administration of pre-determined doses of a sedative/hypnotic drug and a rapid-acting neuromuscular blocker. The difference between an RSI and standard anaesthetic induction is that the anaesthetist does not wait to see the effect of the drugs. Ideally, the endotracheal tube should be in place within 75 seconds of the start of administration of the first drug. Sedatives used include thiopental, propofol, midazolam, and etomidate. Neuromuscular-blocking drugs used include suxamethonium and rocuronium.

Other drugs may be used in a "modified" RSI. Opioids such as alfentanil or fentanyl may be given to attenuate the responses to the intubation process (tachycardia and raised intracranial pressure). This has advantages in patients with ischaemic heart disease and those with intra-cerebral haemorrhage (e.g. after traumatic head injury or stroke).

This procedure is usually performed by doctors in operating theatres and in the emergency department. Paramedics, including aero-medical paramedics can be trained to carry out RSI in certain settings.