RPSGT Exam Oxygen Therapy & Alternative Sleep Treatments — Questions and Answers
Question 1: During a PAP titration study, at what SpO2 level is supplemental oxygen typically added when oxygen saturation remains persistently low despite adequate PAP therapy?
- SpO2 < 95%
- SpO2 < 92%
- SpO2 < 88% (Correct answer)
- SpO2 < 85%
Correct answer: SpO2 < 88%
AASM titration guidelines recommend considering supplemental oxygen addition when SpO2 remains below 88% for more than 5 minutes despite optimized PAP pressure. This threshold aligns with CMS criteria for long-term oxygen therapy and reflects the point at which the hemoglobin-oxygen dissociation curve enters its steep portion.
Question 2: Adaptive servo-ventilation (ASV) is contraindicated in which specific patient population, based on the findings of the SERVE-HF clinical trial?
- Patients with obesity hypoventilation syndrome and hypercapnia
- Elderly patients with complex sleep apnea over age 70
- Patients with heart failure with reduced ejection fraction (EF < 45%) and predominant central sleep apnea (Correct answer)
- Patients with REM-predominant obstructive sleep apnea
Correct answer: Patients with heart failure with reduced ejection fraction (EF < 45%) and predominant central sleep apnea
The SERVE-HF trial (2015) demonstrated significantly increased cardiovascular mortality with ASV in patients with heart failure with reduced ejection fraction (LVEF < 45%) who had predominant central sleep apnea. ASV is therefore contraindicated in this population. This is a critical safety contraindication that all sleep technologists must know.
Question 3: Mandibular advancement devices (MADs) treat obstructive sleep apnea through which primary mechanism?
- Delivering positive pressure to pneumatically splint the upper airway open
- Repositioning the mandible and tongue anteriorly to increase retropalatal and retroglossal airway dimensions (Correct answer)
- Stimulating hypoglossal nerve activity to stiffen the tongue
- Applying negative pressure to the oropharynx to prevent collapse
Correct answer: Repositioning the mandible and tongue anteriorly to increase retropalatal and retroglossal airway dimensions
MADs hold the lower jaw (mandible) in a forward position during sleep, which secondarily advances the tongue base and tenses the pharyngeal walls, increasing the cross-sectional area of the upper airway. They are a guideline-recommended alternative to CPAP, particularly for patients with mild-to-moderate OSA or those intolerant of PAP.
Question 4: Positional obstructive sleep apnea is defined by AASM as an AHI that is at least how much higher in the supine position compared to non-supine sleep?
- 10% higher in the supine position
- At least twice as high (≥2×) in the supine versus non-supine position (Correct answer)
- 50% higher in the supine position
- Any documented difference qualifies as positional OSA
Correct answer: At least twice as high (≥2×) in the supine versus non-supine position
Positional OSA is defined as a supine AHI that is at least twice the non-supine AHI, with the non-supine AHI being ≤ 5 events/hour (some definitions require non-supine AHI < 5 to be truly positional). Patients with positional OSA may respond to positional therapy (devices that prevent supine sleep) as a primary or adjunct treatment.
Question 5: A patient with severe COPD and no co-existing OSA shows SpO2 < 88% for more than 30% of total sleep time on nocturnal oximetry. Which treatment is most appropriate?
- Mandibular advancement device to reduce respiratory effort
- CPAP titration study to treat presumed obstructive apneas
- Nocturnal supplemental oxygen therapy (Correct answer)
- Positional therapy to reduce supine breathing impairment
Correct answer: Nocturnal supplemental oxygen therapy
In COPD patients without OSA, nocturnal desaturation results from hypoventilation and ventilation-perfusion mismatch rather than airway obstruction. CPAP would not correct this. Supplemental oxygen is the appropriate intervention, and criteria for nocturnal oxygen in COPD include SpO2 < 88% for ≥ 5 minutes during sleep, which this patient clearly meets.
Question 6: Which surgical procedure for OSA works by repositioning both the maxilla and mandible anteriorly, creating the largest documented surgical increase in pharyngeal airway volume?
- Uvulopalatopharyngoplasty (UPPP)
- Hyoid suspension
- Maxillomandibular advancement (MMA) (Correct answer)
- Radiofrequency tongue base reduction
Correct answer: Maxillomandibular advancement (MMA)
Maxillomandibular advancement (MMA) surgically moves both jaws forward, expanding the entire upper airway from the retropalatal to the retroglossal level. It has the highest reported surgical success rate for OSA (approximately 86-90%) and produces the greatest increase in pharyngeal volume of any surgical option, but is more invasive than soft tissue procedures.
RPSGT Exam Oxygen Therapy & Alternative Sleep Treatments
During a PAP titration study, at what SpO2 level is supplemental oxygen typically added when oxygen saturation remains persistently low despite adequate PAP therapy?