Endotracheal tube and laryngeal mask airways

[AlexBPS]

Hey

Just seeking some clarification on patient ventilation through an ETT or LMA. I understand the concept of forcing air into the airway through the bag valve mask, but how does the air (CO2) leave when the patient expirates if the ETT/LMA and BVM are in the way?

A.

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[Paseo Del Norte]

Your patient would hopefully exhale gas through the same conduit that gas moved through during inhalation. LMA's and ETT's are not designed to be in the way.

 

[Lawsonc]

Hey

Just seeking some clarification on patient ventilation through an ETT or LMA. I understand the concept of forcing air into the airway through the bag valve mask, but how does the air (CO2) leave when the patient expirates if the ETT/LMA and BVM are in the way?

A.

Those devices are not constant pressure like a CPAP mask, expiration is not an issue. The devices themselves are in the simplest forms "breathing tubes' so direct access to the lungs through the trachea.

If anything expiration is no problem, its keeping PEEP or positive end expiratory pressure in check, as now you have direct access and no natural back pressure to keep the lungs open.

EDIT- that is for the ETT tube, the LMA is not a gold standard definitive airway, it does not access the trachea but rather sits above (laryngeal mask airway)