Sleep Apnea

Question 1

AHI and Classification

Answer 1

• Apnea = >10 sec of no flow
• Hypopnea = dec flow by >30% w/ >4% dec in O2 sat
• AHI (# apnea or hypopnea event s / hr sleep)
  
  • Mild 5-15
  • Moderate 15-30
  • Severe >30

Question 2

Pathophysiology

Answer 2

• Main problem = small pharyngeal airway (genetic, obesity)
• Made worse w/ sleep b/c muscles relax, on back inc neg thoracic pressure, vulnerable period at start of sleep where RR dec so transient hypercapnia
• High CO2 then stimulates normal breathing –> inc arousal –> augment sympathetic tone (which is normally dec in sleep)
• Leads to intermittent hypoxemia –> ischemia/reperfusion fluctuation –> transcription/translation of biomarkers (

Question 3

3 Major Categories of Complications

Answer 3

1- Cardio

- Inc burst of symp tone during arousals --> HR variability (brady- tachy) --> nocturnal up-regulation of symp tone --> diurnal up-reg of symp tone
- Also inc in nocturnal BP --> risk of diurnal HTN

2- Neuro-cognitive

- Sleepiness
- Inc MVA and occupational accidents
- Less daytime function, coordination, vigilance, executive function
- Dec quality of life

3- Metabolic

- Production of biomarkers (CRP, IL-6)
- Inc serum glucose and insulin insensitivity (even when controlling for obesity)
- Elevated leptin (leptin insensitive?)

Question 4

2 Methods of Dx

Answer 4

• Gold std = PSG (EEG, EMG, EOG) (15%)
  
  • Expensive and must do in lab
• Portable Monitor (85%)
  
  • Resp effort, airflow, oximetry and HR
  • Less sensitive, less specific BUT cheaper and more convenient

Question 5

5 Tx Options

Answer 5

1- Conservative Measures (AHI <15 and otherwise healthy)
- Weight loss, lateral position therapy (instead of on back) to keep airway open, avoid alcohol, sedatives, narcotics

2- Poss Pressure Therapy

- Column of pressurized air prevents airway collapse ("air stent")
- Effective immediately
- CPAP (cont), BiPap (bi-level - inc in insp and dec in exp but maintain baseline)

3- Oral Appliances

4- Surgery

- Directed at level of obstruction (retropalatal or retrolingual)
- Less effective in obese pts
- Kids - T&A

5- Neurostimulation/tongue pacing (pacer in intercostals w/ stimulator on hypoglossal nerve)