How much volume is in an adult resuscitator (BVM)? 1600ml

The quick and easy answer to how much volume is in the BVM ventilation bag (the part you squeeze) in an adult resuscitator is 1600ml.

You hear the alarm go through the hospital “CODE BLUE in room XYZ”. You, like me, are an ambulance chaser and want to get there as soon as possible to either run the code or handle the airway or all of the above. A patient needs to be saved! Your team sorts itself out with everyone assuming their roles (or being delegated to their roles). Someone in at the head of the bed with the resuscitator, also known in many places as the “Ambu”.

I sometimes call it the BVM for bag-valve mask. We need to get better at our language in this game. That’s besides the point. So someone is at the head of the bed with a huge adrenaline rush pounding away at the resuscitator squishing the bag ferociously trying to get all the O2’s that exist into the patients lungs RIGHT NOW. More squeeze equals more air and then that’s “more better”, right?  This is too common and this post is to hopefully slow us down when we “bag” the patient. I’m not going to go into proper technique to apply the mask because that’s a topic for another day. The purpose of this post.

The problem is that whether you are utilizing this tool to “bag” someone through a mask or once the endotracheal tube is placed, people bag too much volume and too fast. I’ve seen several cases now where patients have developed pneumothoraces secondary to this issue. People just don’t know the volume of the bag and the fact that you don’t have to squeeze it entirely like you’re trying to get the last of the lemon into your vodka tonic. 1/3 of the way will do.

The reason for this is because our total lung capacity is approximately 6 liters. From those 6L you need to subtract about 1200ml of residual volume and 1200ml expiratory reserve volume. You have 3600cc left to go. Then you bag, bag, bag without allowing time for exhalation and the lungs end up popping like balloons because of the enlarged BVM volume. Then your patient who just coded ended up on a ventilator, whatever the etiology of the arrest was to begin with, and a couple of chest tubes to seal the deal. Be careful with this tool, team.

Credit to Laerdal for publishing the pretty picture and the volume of their resuscitator.
Resuscitator Link

-EJ

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