UMEM Educational Pearls

Category: EMS

Title: Which type of BVM provides appropriate tidal volumes in the back of an ambulance?

Keywords: BVM, tidal volume, TV, ALS, BLS (PubMed Search)

Posted: 10/18/2023 by Jenny Guyther, MD (Updated: 4/24/2024)
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The typical bag valve mask ventilator (BVM) for adults has a reservoir volume between 1500-2000 mL depending on the manufacturer while the volume is between 500-1000 mL for a pediatric BVM.  When trying to obtain the recommended tidal volume of 6-8 mL/kg (500-600 mL for the typical adult), one thought was that a pediatric BVM could be used with adult patients so as to avoid iatrogenic barotrauma.  This has been studied on manakins using an oral pharyngeal airway, supraglottic airway and endotracheal tubes (ETT) and has been successful.  This study attempted to obtain the same results in the back of a moving ambulance.  Paramedics and EMTs, squeezing pediatric and adult BVMs with one hand, bagged adult manakins in the back of a moving ambulance (without lights and sirens).  The average tidal volume was recorded using various types of airways (i-gel, King airway and ETT).

Volumes delivered with the pediatric BVM were significantly lower than the tidal volumes with adult BVMs across all airway types suggesting that in the moving ambulance, using pediatric BVMs on an adult patient would not be appropriate.

The I-Gel and King airway provided similar tidal volumes which were not statistically different than volume delivered through the ETT.

EMTs consistently delivered 50% less tidal volumes compared to paramedics. The authors suggested that perhaps the additional training and pathophysiology knowledge that paramedics have could also be important with a skill that is considered basic. 

References

Sun et al.  Are Pediatric Manual Resuscitators Only Fit for Pediatric Use? A Comparison of Ventilation Volumes in a Moving Ambulance.  Prehospital Emergency Care 2023, 27:4, 501-505.