Which Bag Valve Mask (BVM)?

 

Historically #AirwayNerds we have used an Adult BVM with a potential maximum ventilation volume of 1500-1600 Mls but why do we use this size device and is this still required?

 

The Resuscitation guidelines at the turn of the Millenium suggested that 10-15 Mls per KG should be used in the ventilation of an adult in cardiac arrest. As the maximum IDEAL body weight (IBW) of an adult human is approx 100KG then you can see how the adult BVM size was set!

 

Since then the idea of lesser ventilation in Cardiac Arrest to keep Intra-Thoraccic Pressure down (To Keep Cardiac Output up) and ideas surrounding lung protective strategies now mean we have a recommended tidal volume of 6-8 Mls per KG and many suggest if 5 Mls per KG produces slight chest rise then it is perfectly adequate in Cardiac Arrest.

 

This means for a 70KG adult at 5 Mls per KG the desired tidal volume in Cardiac Arrest may be as low as 350 Mls! It is incredibly difficult to ventilate this amount precisely using a 1500-1600Ml BVM and the potential for over ventilation with the associated complications is fairly obvious particularly in the inexperienced and/or over excited provider.

 

One idea often suggested and supported by us is the use of a Paediatric 500-600 Ml BVM for adults which then means one BVM can be used for all patients, especially as many places have withdrawn 250 Ml Neonatal BVMs as they are always way too large for the required tidal volume of that group!

 

This assists in ensuring a controlled maximum tidal volume even in the most stressful scenarios and also saves on expense and volume of kit carried as a bonus. One day maybe #AirwayNerds (although we have been already waiting some years!) the adult BVM size manufactured will catch up with the clinical guidelines!