Nov 9, 2013
Medical Student
Can someone explain to me Rapid Sequence Intubation and what LMA is?

For some reason I get different responses from different residents.


ASA Member
10+ Year Member
Jan 8, 2007
Attending Physician
Don't ask residents.

Check out an anesthesia textbook or two and see what those sources say. You can also search for relevant journal articles.

Then, when you hear different answers from residents, you have the medical knowledge to ask informed questions.


Laugh at me, will they?
10+ Year Member
Dec 15, 2005
Home Again
Attending Physician
Can someone explain to me Rapid Sequence Intubation and what LMA is?
RSI is a technique by which the patient and induced and the airway is secured with an endotracheal tube as quickly as is safely possible. Typically the induction drug and paralytic are given nearly simultaneously, fast acting drugs/doses are chosen, no attempt is made to ventilate the patient prior to intubation, and some voodoo cricoid pressure is applied to ward off evil spirits. Usual indication is a full stomach, and the objective in intubating quickly is to minimize the time the patient is induced and vulnerable to aspiration. There are some variations to this, but that's the classic unmodified "true" RSI.

LMAs are laryngeal mask airways, big floppy rubbery supraglottic airway devices that are placed blind. They're glorified oropharyngeal airways that keep an airway open. Usually the patient breathes spontaneously throughout the case, but one can apply positive pressure ventilation through them. They don't seal as well as endotracheal tubes though, and excessive pressure can insufflate the stomach, so most people will limit inspiratory pressures to under 20 cmH20. For this reason they're not really appropriate for laparoscopy (though I hear some Europeans go there). Some models allow for decompression of the stomach but mostly they're regarded as not an aspiration-protective device. In selected patients they simplify the anesthetic by allowing one to avoid muscle relaxant (and reversal) and laryngoscopy. They may also reduce the incidence of a sore throat relative to an endotracheal tube.

LMAs are in the ASA's difficult airway algorithm as a rescue device. If a patient is unexpectedly a difficult intubation and you can't mask ventilate, placing an LMA to allow ventilation is next on the list.

An LMA is not going to be a good choice for most RSIs since they don't protect against the main concern you have when doing most RSIs anyway (aspiration).
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