Polysomnogram

Aka: Polysomnogram, Polysomnography, Sleep Study, Obstructive Apnea, Obstructive Hypopnea, Upper Airway Resistance Syndrome, Respiratory Effort Related Arousal, Apnea and Hypopnea Index, Respiratory Disturbance Index, UARS, RERA, AHI, RDI

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II. Indications

  1. Sleep disorder diagnosis
    1. Sleep Apnea (Central Sleep Apnea, Obstructive Sleep Apnea)
      1. Diagnosis and CPAP/BiPAP titration
    2. Narcolepsy
    3. Parasomnia
    4. Periodic Limb Movement Disorder
    5. Rapid Eye Movement Sleep Behavior Disorder
    6. Sleep Related Seizure Disorder
  2. Sleep-related symptom evaluation
    1. Sleep maintenance Insomnia
    2. Snoring
    3. Daytime Sleepiness (unexplained)

III. Definitions

  1. Obstructive Apnea
    1. Air flow decreases 70% for at least 10 seconds with persistent respiratory effort
  2. Obstructive Hypopnea
    1. Air flow decreases 30% for at least 10 seconds with oxygen desaturation >3%
  3. Upper Airway Resistance Syndrome (UARS)
    1. Variant of Obstructive Sleep Apnea
    2. Less airway collapse and less oxygen desaturation
    3. Frequent arousals occur as with OSA/H
  4. Respiratory Effort Related Arousal (RERA)
    1. Abnormal respiratory event associated with an arousal (e.g. gasping) per hour
  5. Apnea and Hypopnea Index (AHI)
    1. Number of Obstructive Apnea and Obstructive Hypopnea events per hour
  6. Respiratory Disturbance Index (RDI)
    1. Apnea and Hypopnea Index (AHI) and Respiratory Effort Related Arousal (RERA)

IV. Technique: Monitors

  1. Electro-oculogram (Eye movement)
  2. Electromyogram (Muscle activity)
  3. Electrocardiogram (EKG)
  4. Nasal pressure transducer
  5. Oronasal thermistor
  6. Oxygen Saturation
  7. Electroencephalogram (EEG)
    1. Sleep Stages
    2. Sleep Latency
    3. Arousals from sleep
  8. Telemetry
    1. Heart Rate and rhythm
    2. Respiratory Rate

V. Types

  1. Overnight Polysomnogram in sleep lab (monitored by attendant, preferred study)
    1. Full night study with subsequent study with NIPPV (CPAP or BiPap) OR
    2. Split-night study (typically diagnostic in first 2 hours with >20 events/h) and NIPPV trial same night
  2. Home study with portable monitors
    1. Precautions
      1. Not recommended for patients with comorbidities (e.g. vascular disease, lung disease)
      2. Less accurate (esp. for fewer channels, when compared with lab study)
        1. Accuracy increases with high pretest probability
    2. Type 2 monitor (7-16 channel)
      1. Test Sensitivity: 79% for AHI 15 (88% for AHI 5)
      2. Test Specificity: 71% for AHI 15 (36% for AHI 5)
    3. Type 3 monitor (4-6 channel)
      1. Test Sensitivity: 64% for AHI 15 (83% for AHI 5)
      2. Test Specificity: 41% for AHI 15 (48% for AHI 5)
    4. Type 4 monitor (2-3 channel)
      1. Test Sensitivity: 67% for AHI 15 (75% for AHI 5)
      2. Test Specificity: 50% for AHI 15 (43% for AHI 5)
    5. References
      1. Qaseem (2014) Ann Intern Med 161(3): 210-20 [PubMed]

VI. Grading

  1. Respiratory Disturbance Index (RDI) <5 apnea/hypopnea events/hour
    1. No Obstructive Sleep Apnea
    2. No treatment necessary except:
      1. Disruptive snoring
      2. Serious comorbidity (e.g. CHF)
      3. Upper Airway Resistance Syndrome
        1. Consider if significant Sleepiness and Fatigue
  2. Respiratory Disturbance Index (RDI) 5 to 14 apnea/hypopnea events/hour
    1. Mild Obstructive Sleep Apnea
    2. Diagnostic if symptoms or cardiovascular comorbidities
    3. Consider Upper Airway Resistance Syndrome
  3. Respiratory Disturbance Index (RDI) 15 to 29 apnea/hypopnea events/hour
    1. Moderate Obstructive Sleep Apnea
    2. Diagnostic for all patients regardless of symptoms or comorbidities
  4. Respiratory Disturbance Index (RDI) >=30 apnea/hypopnea events/hour
    1. Severe Obstructive Sleep Apnea

VII. References

  1. Semelka (2016) Am Fam Physician 94(5): 355-60 [PubMed]

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