Cobra PLA

[crispy91]

I'm currently taking the new AEMT course. In the airway section, one of the advanced airways they mention specifically is the Cobra. There are instuctions for inserting it, but there's no information on the mechanism behind it. It doesn't seem that it would provide much protection from aspiration at all, or really seal off the esophagus.

Can anyone give me any more info on this? How does it work? And what would be the advantage over something like a combitube, or a king airway?

 

[WuLabsWuTecH]

Welcome crispy!

Try this: http://www.pulmodyne.com/Airways/CobraPLA.html

It looks to me like it uses the epiglottis to "seal off" the esophagus. But I agree, idk that it really forms that well of a seal from the materials I read on that page.

 

[Christopher]

I'm currently taking the new AEMT course. In the airway section, one of the advanced airways they mention specifically is the Cobra. There are instuctions for inserting it, but there's no information on the mechanism behind it. It doesn't seem that it would provide much protection from aspiration at all, or really seal off the esophagus.

Can anyone give me any more info on this? How does it work? And what would be the advantage over something like a combitube, or a king airway?

I've only seen these in textbooks and catalogs, never in the field. Granted, you still hear about EOA's--which I thought were grounds for negligence if used--in catalogs or in scope of practice exams.

That being said, it appears to be similar in design to an LMA with aperture bars, with the addition of a retrolingual cuff.

Your use of the word "advantage" is devoid of context, but we can attempt to measure it with respect to items Critical to Quality:

Ease of Use
It has 1 lumen and 1 inflation port for the cuff. This is simpler than a Combitube, and roughly as simple as a KingLT. Insertion times are likely the same as other single lumen supraglottic airways (SGA).

Quality of Ventilation
The cuff design appears similar to all non-LMA designed SGA's. Likely it is meant to fill the retrolingual space to isolate the trachea from the oropharynx. It has an elliptical design similar to a PTL, which may or may not approximate the anatomy better than a Combitube or KingLT. Given an adequate seal, I would imagine this would be functionally identical to non-LMA style SGA's.

The bowl with aperture bars is similar to some of the newer LMA designs. This ensures that even if the epiglottis is captured by the bowl that it does not block the delivery of positive pressure ventilations. The bowl itself is smaller than an LMA/iGel/Air-Q but larger than a Combitube/KingLT. This could conceivably make it easier to ventilate by lowering the pressures generated through lumen narrowing.

Isolation of Tracheal Inlet/Esophagus
In this realm the Cobra appears inferior to other SGA designs. Depending on where the bowl seats, it could conceivably provide positive pressure ventilations into both the tracheal inlet and esophagus or even just the esophagus. Likely, a strategy similar to the KingLT needs to be used on insertion which encourages a gradual retraction after cuff inflation to ensure a proper seating of the cuff and proper alignment of the bowl.

Does it even matter?
In all likelihood, the usage of a Cobra PLA would be found to be non-inferior to other similar SGA's. I think it would be safe to say that it would also be found to have faster insertion times versus a Combitube. Ventilatory performance should be on par with other SGA's. However, given the bowl design it seems likely that this SGA would introduce larger volumes of positive pressure ventilations into the esophagus versus designs which attempt to isolate tracheal inlet.

SGA design is a very interesting field and recently there have been lots of great discussions at the EMCrit and PHARM podcasts.