Rapid sequence induction
It differs from other techniques for inducing general anesthesia in that several extra precautions are taken to minimize the time between giving the induction drugs and securing the tube, during which period the patient's airway is essentially unprotected.
[3] RSI is typically used in patients who are at high risk of aspiration or who are critically ill and may be performed by anaesthesiologists, intensivists, emergency physicians or, in some regions, paramedics.
In this situation, one must consider the difficult airway algorithm[6] with the possibility of waking the patient with paralytic reversal medications such as sugammadex.
[7] Neuromuscular blockade agents are considered one of the highest anaphylaxis-inducing substances in the operating room, along with latex, penicillin, and chlorhexidine.
[5] The process of applying cricoid pressure during Sellick's maneuver can introduce complications such as laryngeal distortion, failure to completely occlude the esophagus, and potential esophageal rupture if the patient is actively vomiting.
[30] Newer methods of preoxygenation include the use of a nasal cannula placed on the patient at 15 LPM at least 5 minutes prior to the administration of the sedation and paralytic drugs.
After apnea created by RSI the same high flow nasal cannula will help maintain oxygen saturation during efforts securing the tube (oral intubation).
[31][32] The use of nasal oxygen during pre-oxygenation and continued during apnea can prevent hypoxia before and during intubation, even in extreme clinical cases.
With standard intravenous induction of general anesthesia, the patient typically receives an opioid, and then a hypnotic medication.
However, the difference lies in the fact that the induction drug and neuromuscular blocking agent are administered in rapid succession with no time allowed for manual ventilation.
The neuromuscular blocking agents paralyze all of the skeletal muscles, most notably and importantly in the oropharynx, larynx, and diaphragm.
Opioids such as fentanyl may be given to attenuate the responses to the intubation process (accelerated heart rate and increased intracranial pressure).
First described by William Stept and Peter Safar in 1970, "classical" or "traditional" RSI involves pre-filling the patient's lungs with a high concentration of oxygen gas; applying cricoid pressure to occlude the esophagus; administering pre-determined doses of rapid-onset sedative and neuromuscular-blocking drugs (traditionally thiopentone and succinylcholine) that induce prompt unconsciousness and paralysis; avoiding any artificial positive-pressure ventilation by mask after the patient stops breathing (to minimize insufflation of air into the stomach, which might otherwise provoke regurgitation); inserting a cuffed endotracheal tube with minimal delay; and then releasing the cricoid pressure after the cuff is inflated, with ventilation being started through the tube.
[37][38][39] There is no consensus around the precise definition of the term "modified RSI", but it is used to refer to various modifications that deviate from the classic sequence – usually to improve the patient's physiological stability during the procedure, at the expense of theoretically increasing the risk of regurgitation.
[2] Examples of such modifications include using various alternative drugs, omitting the cricoid pressure, or applying ventilation before the tube has been secured.
Alternative airway management devices must be immediately available, in the event the trachea cannot be intubated using conventional techniques.
RSI is mainly used to intubate patients at high risk of aspiration, mostly due to a full stomach as commonly seen in a trauma setting.
The patient is given a sedative and paralytic agent, usually midazolam / succinylcholine / Propofol and intubation is quickly attempted with minimal or no manual ventilation.
