Sleep and hypoventilation

Question 1

Clues from sleep study that central sleep apnoea?

Answer 1

No flow = apnoea
No abdo or thorax effort (would be there if OSA)
Associated with desaturation

Nb. Central sleep apnoea more common in pt with HF and MI

Question 2

Pt has OSA but are not sleepy. Do they need to inform DVLA?

Answer 2

No

Question 3

Pt has OSA and are sleepy. Do they need to inform DVLA?

Answer 3

Yes unless mild where can wait 3 months (although still can’t drive and if still sleepy then must tell DVLA)

Question 4

But has ODI of 32. What are the implications on driving?

Answer 4

If sleepy then must not drive an inform DVLA (severe OSA)

If no longer sleepy and show treatment compliance, then can restart
–> mod/severe OSA need to show treatment compliance when symptoms resolved before resuming driving

Question 5

What are definitions of OSA?

Answer 5

Apnoea-hypopnoea index
Normal <5
Mild 5-14
Moderate 15-29
Severe 30+

Question 6

What is the difference between polygraphy and polysomnography?

Answer 6

Polygraphy is the HR, SATS, nasal flow, chest movement etc.

Polysomnography also has EEG, eye movements etc

Question 7

What is best test of OSA?

Answer 7

Polygraphy

Question 8

What is treatment of OSA?

Answer 8

Lifestyle advice
+ fixed level CPAP if moderate severity or above or mild with symptoms affecting QOL

+/- consider tonsillectomy
+/- treat rhinitis
+/- mandibular advance device (if intolerant to CPAP)

Question 9

When should auto-CPAP be considered in OSA?

Answer 9

If high pressure only needed at certain times of night
OR can’t tolerate fixed-level CPAP
OR telemonitoring can’t be used

Question 10

What preliminary test can be done to screen for OHS if pre-test probability low?

Answer 10

Bicarbonate as <27 = unlikely OHS

Question 11

What tests should be done to diagnose OHS?

Answer 11

ABG/CBG when awake (pCO2 >6)
Polygraphy +/- CO2 monitoring
BMI >30

Question 12

What is treatment for OHS?

Answer 12

Without acute episode ventilatory failure AND pCO2<7
+ severe OSA –> CPAP. R/v at 3/12: if symptoms don’t improve or remain hyperCO2 then try NIV
- OSA or non-severe OSA –> NIV
+ COPD –> NIV

With acute episode of ventilatory failure
+ OSA –> NIV but consider CPAP once stable

Question 13

When should overnight oxygen be considered in OHS?

Answer 13

Hypoxia despite good AHI and nocturnal hypoventilation control

Question 14

Pt has COPD and OSA. Should you use CPAP or NIV?

Answer 14

pCO2<7 –> CPAP
>7 –> NIV

Question 15

When should pts started on CPAP/NIV for OSA or OHS be followed up?

Answer 15

1 month
Telemonitoring for a year

Question 16

When should NIV be used in MND?

Answer 16

SOB particularly orthopnoea
Daytime sleepiness
Daytime pCO2 >6
Nocturnal desaturation or daytime SATS <94
FVC<50 (or <80 with symptoms/signs)
Postural VC drop

Question 17

What is REM behaviour disorder?

Answer 17

New onset sleep-talking, punching, kicking
Can be ass with Alzheimers, Parkinsons, Stroke
Can be ass with SSRIs

Tx: conservating, clonazepam, melatonin

Question 18

What are RFs for central sleep apnoea?

Answer 18

Older age
Male
Opioid use
Cardiovascular disease