Sleep Apnoea

Question 1

What is apnoea and hypopnoea?

Answer 1

Apnoea = complete cessation of ventilation for >10 seconds

Hypopnoea = partial reduction in ventilation

Question 2

OSA is defined as AHI - what is it and how would you classify severity of disease?

Answer 2

Apnoea-Hypopnoea Index.

If more than 5 per hour → OSA

Mild: 5-15

Moderate: 15-30

Severe >30

Question 3

What is the implication of OSA in perioperative period? (5)

Answer 3

Increased risk of respiratory Failure

For orthopaedic surgery: increased risk of PE, ARDS, intubation, Aspiration

Question 4

OSA: PRIC-MCP

Symptoms? (7)

Answer 4

Snore (if no snoring, suspect CSA)

Apnoea (>10 seconds significant; and sleep arousals)

Excessive daytime somnolence

Fatigue

Early morning headaches

Epworth sleepiness scale*** (2 key questions)

• Do you fall asleep when watching news/movie?
• Do you feel safe to drive / or fall asleep when the car is stopped for few minutes for traffic?

Question 5

Epworth Sleepiness scale? What is rough score for normal individual and likely sleep apnoea?

Answer 5

Epworth score >10 makes sleep apnoea likely (likely severe).

<8- unlikely to have sleep apnoea.

Question 6

OSA History: PRIC-MCP

Risk factors? (7, 3 in question)

Answer 6

Obesity

Older age

Male

Smoking & Alcohol

For questions - just 3

Family history

Anatomical (enlarged tonsils, previous tonsillar surgery)

Hypnotics (e.g. BDZ, narcotics, gabapentinoids)

Question 7

OSA - things to comment on examination?

Answer 7

BMI (chart)

Pulse - AF

BP / fundoscopy (HTN)

Mallampeti

Signs of pulmonary HTN

Question 8

OSA History: PRIC-MCP

Investigations? (3)

Answer 8

Sleep study (polysomnography) - looking for Apnoeas >10 seconds ≥5 episodes / hr and calculate AHI to grade severity or MWT (Maintenance of Wakefulness Test) - where patient is placed in a room for 40 minutes and stay awake for 40 minutes

• Also to look for complicaitons such as hypoxia, hypercapnoea, arrythmia (ECG)
• To exclude other differentials: CSA and Narcolepsy

TFT to exclude hypothyroidism

TTE: RVSP and RV function

Question 9

OSA History: PRIC-MCP

Complications? (5)

Answer 9

HTN

IHD & CCF

Pumonary HTN

Arrythmia

Social / occupational impact

Question 10

How would you manage this patient with OSA?

Answer 10

Goal: halt disease progression, improve self-efficacy (and compliance), prevent complication

Confirm diagnosis: ask for PSG

A: identify & treat hypothyroidism, nasal obstruction, depression, smoking and ETOH

T: Non-pharm

• Educate - morbidity & life-thretening complications, impact of non-pharm Mx
• Weight reduction: exercise, diet (Meditteranean, low fat, low-energy/calorie diet)
• Avoid respiratory depressants
• Good sleep hygiene with regular sleeping routine
• Address fitness for driving: refer to resp (if not already), consider regular MWT

T: Pharm

• CPAP is gold standard (adherence rate >70%)
• Mandible advancement splint
• Surgical correction of upper airway narrowing by polyps, enlarged tonsils, macroglossia
• BiPAP for CSA (but NOT ASV - adaptive servo-ventilation as it increases mortality)

Ensure FU and screen for complications

• Clinical examination for HTN, pulmonary HTN
• TTE
• Consider WMT

Question 11

What is the definition of Obesity Hypoventilation syndrome?

Answer 11

Clinical syndrome defined as the presence of awake alveolar hypoventilation (PaCO2 >45) in obese patient (BMI >30), which cannot be attributed to other conditions a/w hypoventilation.

Question 12

How would you investigate suspected OHS? (4) and treatments (2)

Answer 12

Clinical manifestations of OHS are non-specific and more reflective of manifestations of obesity, coexistent OSA (90%) and it’s complications (e.g. pHTN).

Work up:

EUC for bicarb (>27) should prompt further investigations

ABG - hypercapnoea and chronic respiratory acidosis

Polysomnography

TTE to look for pulmonary HTN + RVF

Treatment is with BiPAP +/- O2 through it (if hypoxic) - but never O2 alone. Weight loss is main stay of therapy,

Question 13

Restless leg - diagnosis? (features in history)

Answer 13

Largely clinical.

1) Urge to move limbs
2) Rest precipitates it
3) Eases when moving
4) Worse in evenings

Sleep study not required by will show periodic leg kicks.

Question 14

How would you manage this patient’s restless legs?

Answer 14

Goals: control symptoms, prevent complication, identify & treat secondary causes

Confirm dx: history, PSG (periodic leg kicks)

A: work-up for secondary causes - 1) Fe deficiency, 2) ESRF (Uraemia), 3) Neurological (spinal cord, MS, Parkinson’s, PN of any cause), 4) Medications (TCA, SSRI, antipsychotics), 5) Diabetes

T: Non-pharm

• Mainstay: only treat with drugs if very severe
• Avoid precipitating drugs, caffeine, alcohol
• Exercise, leg massage, applied heat
• Mental activation activities

T: Pharm

• Replace iron (if ferritin <50)
• Dopamine agonist (pramipexole, ropinirole, ritogotine) - successful in 80%, 20% can cause augmentation (paradoxical worsening)
• Gabapentinoids (gabapentine, pregabaline) - no risk of augmentation
• Choice depends on other indications (e.g. if depressed, dopamine agonist, if pain/insomnia - gabapentinoids)
• Rescue tx with opioids or long acting BDZ