Answer: Great question. The use of the BVM is a decision that paramedics make every day based upon judgment as to the patient’s level of consciousness and respiratory effectiveness/distress as well as where indicated by the BLS Patient Care Standards.
If a patient is in respiratory distress and has an oxygen saturation of < 90% or accessory muscle use such that CPAP would be considered (and CPAP is not available) then it would be reasonable to consider using a BVM to assist with ventilations.
Strictly speaking however, providing ventilations through the BVM does not provide a continuous level of airway pressure (although with the use of a PEEP valve on a BVM we may be able to approach some level of continuous airway pressure) therefore the physiology (and potentially the benefit) may not be the same. Bottom line: the use of the BVM is a skill that paramedics must be familiar with and used as per their own judgment and the BLS Patient Care Standards but not as a substitute for CPAP.