Introduction to PAP Flashcards
NICE recommends CPAP as the gold-standard treatment for OSAHS in addition to lifestyle changes, where appropriate, for moderate to severe OSAHS and where mild but with symptoms affecting quality of life and daytime activities. Fixed level CPAP is considered the first line and this is mostly based on cost and lack of concrete evidence on the superiority of auto-CPAP for its given level of cost (hence the reccomendment to use auto – CPAP where it can be supplied at the same price or lower than fixed CPAP).
What is CPAP?
Application of continuous positive pressure to the upper airways, either through the nares (nasal mask) via the oronasal route (full face mask). It acts as a pneumatic splint to maintain upper airway patency.
Contraindications to CPAP
- hx of facial, oral or skull surgery or trauma
- history of severe nosebleeds
- pneumothorax
- severe cardiac arrhythmia or coronary artery disease
- acute sinusitis
Absolute contraindications include active vomiting due to the risk of aspiration. CPAP should not be used in someone who is not spontaneously breathing or in someone who is not cooperative. Although CPAP might be the best treatment for someone it is not something that can or should be forced onto someone, even those who lack capacity.
Clinical outcomes from CPAP
CPAP can help resolve symptoms such as excessive sleepiness, morning headaches, nocturia, tiredness. It reduces snoring and can therefore help with strained relationships where snoring is disturbing a partner’s sleep. It can also improve other health outcomes such as improving hypertension control, diabetic control, asthma contol. It improves health related quality of life and neurocognitive performance.
Modes of CPAP
Fixed CPAP does what it says on the tin. A pressure is set and that pressure is delivered constantly (although it may drop on expiration when the comfort setting known as Expiratory Pressure Relief is used). This fixed pressure is predicted using a formula based on factors e.g. BMI/ neck circumference and oxygen desaturated/ apnoea hypopnea index
Auto-CPAP or APAP is an adaptive pressure which changes and increases in response to various respiratory events such as snoring, apnoeas and hypopnoeas in order to prevent further events. It will also reduce pressure when there are long periods with no event in order to minimise the pressure delivered.
pros and cons of fixed CPAP
Advs:
- does not react to mask leak
- no pressure changes that could cause arousals
– less expensive
- pressure can be checked using pressure gauge to ensure working correctly
Disadvantages:
- pressure may be set too high/ low
- titration is time consuming
- lower compliance
- older machine reports only show usage
- higher mean pressures
- will not react to factors that increase airway resistance (alcohol, medication, posture)
APAP pros and cons
ADvs:
- lower mean pressure
-improve comfort
- differentiate between central and obstructive vents
- able to give detailed data such as mask leak, AHI and pressures
- Abel to adapt to factors that may increase airway resistance (posture, alcohol, meds etc)
Disadvantages:
- inappropriate detection of events due to mask leak
- more expensive
- malfunctioning cannot be ruled out
- algorithms often not divulged
- pressure changes may cause arousals
Side effects with CPAP
- nasal congestion
- pressure sores
- noisy
- mask leak
- mouth dryness
- air swallowing
