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A Comprehensive Educational Website (established 1998)

Designed, Produced, and maintained (Edition 12, 2022) by 

Bhavani Shankar Kodali MD

Updated September 2022

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LMA and Capnography

PETCO2 measured via LMA or ETT correlate well with PaCO2 during mechanical ventilation in children as well as in adults breathing spontaneously

 PETCO2  measured via ET tube                                PETCO2 measured via LMA
 /Clinicalapplication/lmaet.gif  /Clinicalapplication/lma.gif

During spontaneous ventilation in adults, the mean difference between PaCO2 and PETCO2 measured via LMA is similar to that measured via endotracheal tube.1 However, in children, PETCO2 measured via LMA does not accurately reflect PaCO2 in spontaneously breathing children.2 On the other hand, infants and children weighing less than 10 kg who are mechanically ventilated via the LMA, PETCO2 is as accurate an indicator of PaCO2 as when ventilated via LMA.3

1. Hicks I, Soni N, Shephard J. Comparison of end-tidal and arterial carbon dioxide measurements during anaesthesia with laryngeal mask airway.  Br J Anaesth 1993;71:734-5.
2. Spahr-Schopfer IA, Bissoonnette B, Hartley EJ. Capnometry and the pediatric laryngeal mask airway. Can J Anaesth 1993;40:1038-43.

3. Chhibber AK, Kolano JW, Roberts WA. Relationship between end-tidal and arterial carbon dioxide with laryngeal mask airways and endotracheal tubes in children. Anesth Analg 1996;82:247-50.]