Obstructive Sleep Apnoea CPOC

Question 1

Define apnoea and hypopnea

Answer 1

• apnoea: complete obstruction and cessation in breathing for 10 secs
• hypopnea: Partial obstruction and air flow halved for 10 secs

Question 2

Apnoea/ Hypopnea Index

Answer 2

Number of apnoea and hypopnea per hour

<5- Normal
- 5-15 Mild OSA
- 15-30- Moderate OSA
- >30- Severe OSA

Question 3

Pathophysiology of OSA

Answer 3

Upper airway obstruction from increased soft tissue/ large adenoids etc leads to a PaCO2 rise
-> Central chemoreceptor stimulation -> Deep inspiration + Partial Arousal
-> Repeated frequent sympathetic stimulation (rise in HR &BP) throughout sleep
-> Daytime somnolence, chronic HTN

Question 4

Investigations for OSA

Answer 4

Gold standard- inpatient polysomnography (ECG, EEG, EMG, SpO2, oro-nasal airflow)
Commonly- overnight oximetry at home, >4% dip = Apnoea/ hypopnea event. Gives ODI (oxygen desat index)

Question 5

STOP-BANG

Answer 5

S= Snoring
T= Tiredness in daytime (excessive)
O= Observed to stop breathing (apnoea)
P= Pressure high (BP (>140/90)

B= BMI >35
A= Age >50
N= Neck circumference >40cm
G= Gender - male

5-8 = high probability
>3 = probable (do serum bicarb)

Question 6

Treatment of OSA

Answer 6

• Weight loss
• Stop smoking
• Decrease alcohol/ sedative medication consumption
• CPAP
• Mandibular advancement devices
• Adenotonsillectomy
• Uvulo-palato- pharyngoplasty

Question 7

Pre-Operative Considerations for OSA

Answer 7

• If elective surgery establish on and ensure good compliance with CPAP
• Weight loss
• Smoking cessation
• Ensure patient brings CPAP machine with them
• Risk stratification based on co-morbidities: IHD, HTN, NAFLD, Asthma
• Consider checking rt heart function- ECG, ECHO
• Avoid sedative pre-medications

Question 8

Intra-Operative Considerations for OSA

Answer 8

• Senior anaesthetist
• Avoid GA when possible
• Caution with intra-scalene blocks due to risk of phrenic nerve palsy
• Plan for difficult BMV, hypoxia and difficult intubation
• Avoid long acting opioids where possible
• Consider arterial line esp if evidence of right heart issues
• Extubate fully awake and reversed, upright

Question 9

Post-Operative Considerations for OSA

Answer 9

• Continuous SpO2 monitoring
• Use CPAP in recovery if severe
• Consider HDU
• Avoid long acting opioids