Sleep/Ventilation

Question 1

When should you inform the DVLA if experiencing sleepiness?

Answer 1

• Confirmed diagnosis of moderate or severe OSA with excessive sleepiness
• Either narcolepsy, cataplexy or both
• Excessive sleepiness with any other sleep condition including for at least 3 months including suspected/confirmed mild OSA
  If excessive sleepiness but not confirmed OSA then should not drive but no need to inform the DVLA

Question 2

What is the recommended diagnostic test for people with OSA?

Answer 2

Home polysomnography. If this is not readliy available then can use overnight oximetry (although not very specific)

Question 3

What is the best initial test for suspected OSA?

Answer 3

Home polygraphy (limited sleep study incorporating O2 levels and resp muscle movements). If this is not available then overnight oximetry may be considered.
Consider polysomnography if home polygraphy is negative but symptoms continue

Question 4

What is the recommended treatment for Mild OSA?
Does this change if symptomatic?

Answer 4

Usually if mild (AHI 5-<15) and asymptomatic/mild symptoms then no specific treatment required. Improve sleep hygiene and lifestyle measures (wt loss, smoking cessation, reduce alcohol intake)
If symptomatic affecting day-to-day functioning then offer FIXED LEVEL CPAP alongside lifestyle advice. Can also trial if lifestyle advice unsuccessful.
If FIXED level not tolerated then can offer auto CPAP. Also if high pressures only needed at certain times during sleep.

Question 5

What are the treatments for rhinitis in OHS?

Answer 5

Trial of nasal steroids/antihistamines in allergic rhinitis
Trial of nasal steroids in vasomotor rhinitis

Question 6

When should you suspect OHS?
What are the diagnostic tests for OHS?

Answer 6

Features of OHA/Hypopnoea syndrome
Waking headaches, peripheral oedema, unexplained polycythaemia, hypoxaemia
BMI >30
Measure serum bicarbonate- if <27mmol/L then OHS is unlikely
WAKING measurement of CO2
Sleep study (usually home polygraphy) ideally with transcutaneous CO2 monitoring (TOSCA)
DO NOT USE PULSE OXIMETRY ALONE

Question 7

How is OHS treated?

Answer 7

If severe OSAHS and OHS then offer CPAP as first line therapy
If persisting hypercapnia despite CPAP, symptoms not improving or insufficient reduction in AHI/ODI then offer NIV.
Consider NIV first line if OHAHS not severe or not present
Offer NIV if acute hypoventilatory failure

Question 8

What is the blood gas cut off when deciding treatment in COPD-OSAHS overlap syndrome?

Answer 8

PaCO2 of 7- if 7 or less then consider CPAP as first line treatment
If PaCO2 >7 then consider NIV as first line treatment

Question 9

What happens to central apnoeas during REM sleep?

Answer 9

Central apnoea is more common during NON-REM sleep. Usually awake ventilatory drive overrides central apnoea when awake. During non-REM sleep this is worse as no overriding factors but diaphragmatic activity is present during REM sleep, although erratic.
The diaphragm is not paralysed in REM sleep so ventilation can often improve.

Question 10

What are the relative risks of developing a fatal cardiac event in untreated moderate OSA?

Answer 10

Risk is 2-3 times greater than normal population if left untreated

Question 11

When monitoring FVC in GBS, at what point would you be concerned about developing severe respiratory failure?

Answer 11

If FVC falls below 20ml/kg of body weight e.g. in a 70kg individual, FVC of 1.4L is the cutoff.