How to Insert a Laryngeal Mask Airway
Laryngeal Mask Airways have become increasingly popular in theatres (for minor surgery procedures with low risks of aspiration) and even in pre-hospital care as a good alternative to Endotracheal Intubation.
It should be noted that although LMA insertion is easier than ET insertion it is not as stable an airway and does not protect the airway from potential vomiting. This said, LMA insertion is easier and less likely to fail.
Like any other medical procedure (even in an emergency) it is always important to prepare the patient, as much as preparing the equipment.
When I’m about to insert an LMA I like to adequately assess the patency of the patient’s airway before insertion, with simple airway manourvres such as: jaw thrust, head tilt, and chin lift. I then pre-oxygenate the patient, by ventilating with a Bag Valve Mask with 100% Oxygen for at least two minutes before hand.
I then prepare the equipment. This will include, the Laryngeal Mask Airway, syringe, lubricating gel, bite block (or oropharyngeal airway), trachy ties or tape, and scissors. I also make sure my stethoscope is handy.
I then select the size LMA. Each brand of LMA appears to have a different system. The brand that we use currently are broken down into small patients, medium sized patients, and large patients. However, it should be noted that larger patients (although technically requiring a larger LMA, sometimes, due to the size of an obese person’s neck, or a person with a particularly short, thick neck, a smaller size LMA may be the only size that actually fits. Each LMA is designed differently, so review the packaging and manufacturer’s advice on this topic.
Lubricate the posterior surfaces of the LMA (but don’t worry if you get some lubricant on the anterior side surface of the LMA, this wont affect anything).
Check to make sure that the valve depressor is inserted into the indicator bulb (this keeps some pressure in the LMA, and stops it folding back so easily).
Position yourself ideally behind the patient’s head.
Place the patient in a supine position and then into the “sniffing” position.
Use some pressure with your non-dominant hand on the jaw to allow enough room to insert the LMA with your dominant hand.
Hold the LMA with your dominant hand and insert the airway over the top of the tongue and pushing it backwards until it reaches the hard palate (back part of the oropharynx).
Advance the LMA as far back as possible.
Remove the valve depressor and insert the required inflation amount of air (often about 20-30 minutes, but may vary depending on brands).
Immediately after insertion, auscultate the patient’s lungs to ensure that you have correct placement of the LMA and that it is providing a patent airway.
Insert a bite block to stop the patient biting down on the LMA tube
Tie the LMA tube to the lip. To do this, tie a knot at the top lip. This is because the top lip does not move, where as the jaw (mandible) will likely move.