Answer: You are correct, Positive End Expiratory Pressure (PEEP) is not exactly the same as CPAP. PEEP can be administered by application of a PEEP valve to a BVM. PEEP works by limiting exhalation by way of maintaining a small amount of positive pressure. This helps to splint alveoli open, and increases functional residual capacity, which is the volume of gas that remains in lungs after a normal breath. CPAP, on the other hand, provides continuous positive pressure throughout the respiratory cycle, thereby improving oxygenation and tidal volumes.
The issue of CPAP vs BVM has been brought up with Ask MAC previously, so some of the following is taken from that (from Nov. 2013)
Both interventions may lead to improved lung compliance and reduced work of breathing. This effect will be much more prominent in the case of CPAP compared to PEEP. Nonetheless, the decision to use a BVM is a decision that must be made on paramedic 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 less than 90% or accessory muscle use such that CPAP would be considered (and CPAP is not available or contraindicated) then it would be reasonable to consider using a BVM to assist with ventilations. In this case, using a PEEP valve on the BVM would be of benefit. As PEEP valves are not controlled medical acts, these equipment components fall under the oversight of paramedic services.
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.