I read this somewhat interesting letter to the editor in the latest issue of Acta Anaesthesiologica Scandinavica, and it caught my attention. I believe this has to do with the fact that in airway management topics, there are more “factoids” than actual “facts”. Believe it or not I posted this question to some of the most prestigious minds in the airway related community, and most sidestepped an answer. And so my question goes for you: Is the LMA classic a secure airway? If “yes”, only for certain procedures, or only for certain patients? And if “No” is it because it does not a gastric aspiration port? Which then leads to the next obligatory question: Are the ProSeal and/or Supreme LMA’s, secure airways?
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Sep
Sep
The LMA “classic” is it a secure airway
5 Responses to “The LMA “classic” is it a secure airway”
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Associate Professor of Anesthesiology at the University of Florida; I did my residency then fellowship in Cardiothoracic anesthesia, completed a Masters In Education at UF in 2012 and have been a UF/VA staff anesthesiologist since 2000. I was also the Director of the Master of Education Fellowship from the C.O.M. until the course was terminated. I am responsible for the Difficult Airway Rotation at the UF and Airway Management Services at the NFSGVHS. My interests include: 1-Airway related topics 2-Education about Airway management 3- Resident training in Airway management 4-Non-Anesthesia providers airway training and education 5-Education in general and specifically technology in education.
In my opinion a protected airway is one that gives a reasonable amount of confidence that stomach contents cannot enter the lungs. Having a port to suction the stomach may decrease the contents available to enter the airway, but I would not say this “secures” the airway. While you may get seals more than adequate for ventilation with these devices there is still no guarantee of a seal that cannot be dislodged or allows occult leakage of stomach contents. If I feel there is a risk for aspiration I would opt for an ETT, regardless of ability to suction the stomach.
Posted on September 22nd, 2009 at 4:31 pmI think this is a very reasonable response and my guess is that at least 50% of people will agree with you; there are still many others specially outside the U.S that use SGA’s far more often than we do here, and for procedures we would not even consider it. I think the issue with these SGA’s is far from over. I am surprised how we have come to accept many “factoids” about them. If you go to the LMA website there are some intersting figures that as far as I know will never be able to be confirmed i.e “LMA Classic™ has been used in over 100 million patients worldwide”… how do they really know?; based on sales? how many times have you submitted a report to the LMA co. stating how often you use it? I bet you $ none… so how do they really know how many times has it ever been used? and the way that apparently Dr. Brain -whom do not get me wrong- deserves all the credit in the world, came to its design and apparently “used it in 7000 patients before it was introduced in the clinical arena”… I do not know, has anyone really ever confirmed these numbers? My point is that before we accept anything, I am of the philosophy that I like to see objective facts…. otherwise how do I know I am not dealing with sales people factoids?
Posted on September 22nd, 2009 at 5:42 pmIt seems some studies have measured lower esophageal sphincter pressure or esophageal pH as indirect means to asses reflux with LMA use. Here is an article that uses gastric distension as a measure of reflux risk when comparing LMA to ETT use during laparoscopic surgery.
http://msquared.anest.ufl.edu/Library/Airway/LMA_ProSeal_Classic_Laparoscopy_Plus_Editorial.pdf
The data show that the LMA is safe, provided you make perfect patient and LMA selection (e.g. choose the best LMA for those with restrictive lung disease/obesity, like a Proseal).
Despite this data, it seems no author will come off the fence and definitively claim any LMA equal to an ETT for intra-abdominal surgery.
As sales people put more fancy additions to the LMA (like a gastric port and extra balloons) it will eventually look like a combitube!
Fow now, only an ETT is a secure airway, period. In certain situations, the LMA might be ‘secure enough.’
Posted on September 24th, 2009 at 8:58 pmThis is both a technical question but begs for a philisophical interpretation. Technically, as others have commented, the “secure” part of an airway description suggests that the airway will not become insecure as events in the airway change. Therefore, even as there may be regurgitation, there should be no aspiration, or even as chest wall or lung compliance may decrease, ventilation can still be provided because the seal pressure can be increased. Hence, a “secure” airway does require an endotracheal location AND a cuff. The philisophical perspective looks at the question in absolutes. There are ailure modes of a cuffed ETT, too. We know lasers can puncture cuffs, and a proper seal is either minimal leak (or seal), so there can be leaks. In fact, we know that micro-aspirations and ventilator-associated pneumonias occur, presumably from leaks around cuffs. SGA’s in their current configurations, anyhow, should not be considered “secure,” no matter how well they may be taped in.
Posted on September 29th, 2009 at 2:55 pmExcellent points, and I agree with you. However, I must point out that some UK LMA enthusiasts like Dr. Verguese consider that as long you have a gastric port and that you position either the Proseal or Supreme correctly, it should be O.K, even for gastric procedures. The LMA Classic on the other hand….
Posted on September 29th, 2009 at 3:10 pm