CPAP (Continuous positive airway pressure) is the use of continuous positive pressure to maintain a continuous level of positive airway pressure, in a spontaneously breathing Pt.
What is CPAP?
Positive pressure, is used continuously, to maintain a positive pressure in the airways. This means that the airway is kept open by the air pressure, so that it is possible to breathe. It's important to know that it's not the movement of air, but the air pressure, that opens up the airway.
Functionally the same as PEEP (Positive End Expiratory Pressure), as both are used to stent alveoli open, and recruit alveoli of the lungs for more surface area for ventilation
CPAP is continuous positive airway pressure, using constant mild air pressure to keep an airway open, maintaining a constant PEEP, rather than only at end expiration (cycling)
Patients must initiate all of their breaths
CPAP machines can be used at home
Some CPAP have other features, including heated humidifiers
CPAP delivery through nasal mask is the most common modality, but there are other interfaces, including including oral/naso-oral masks (used when nasal congestion/obstruction is an issue)
What is PEEP, and how is it related to CPAP?
PEEP is positive pressure in the lungs, after breathing out. This is equivlent to not breathing out completely, meaning that the lungs won't fully collapse, and breathing will be possible.
BiPAP (Bilevel positive airway pressure) is a mod of CPAP, that uses time-cycled or flow-cycled change between 2 different applied levels of positive airway pressure (cf CPAP which uses a SINGLE level of positive airway pressure throughtout the whole respiratory cycle). It generates inspiratory (IPAP) and expiratory (EPAP) pressure gradients that complement the Pt's own respiratory cycle, optimizing the lung's efficiency, and reducing the WOB.
What is BiPAP then? And how's it different from CPAP?
Rather than just maintaining a single CONTINUOUS pressure. BiPAP uses 2 pressures, 1 for breathing out, and 1 for breathing in. It's helpful for patients who find it hard to force air out, against incoming air.
Typically used in Pt's who have breathing problems (e.g. sleep apnea), preventing the airways from collapsing or becoming blocked
Frequently used in preterm infants whose lungs have not fully developed (e.g. respiratory distress syndrome), as it is associated with improved survival, decreased need for steroid Tx, and a decrease in incidence of bronchopulmonary dysplasia. Its use is nonetheless controversial