Treatment of Sleep-Related Hypoventilation

Diagnosis and Assessment

• The American Academy of Sleep Medicine recommends polysomnography with continuous CO2 monitoring as the gold standard for diagnosis and assessment of sleep-related hypoventilation 1, 2
• Overnight pulse oximetry with continuous CO2 monitoring can be used to monitor nighttime gas exchange in areas where polysomnography is not readily available 1
• Simple oximetry alone provides only indirect information on ventilation and should be used only when better alternatives are unavailable 1
• Serum bicarbonate >27 mmol/L can be used as a screening tool to identify patients who may need arterial blood gas analysis to diagnose hypoventilation 3

Treatment Algorithm

• The American College of Chest Physicians recommends CPAP therapy as first-line treatment for stable ambulatory patients with Obesity Hypoventilation Syndrome (OHS) and severe OSA (AHI >30 events/h) 4, 5
• Noninvasive ventilation (NIV) is recommended for OHS patients with sleep hypoventilation without severe OSA 4, 5
• The American Thoracic Society recommends starting NIV therapy before hospital discharge for hospitalized patients with respiratory failure suspected of having OHS 4, 5
• Target sustained weight loss of 25-30% of actual body weight to achieve resolution of hypoventilation 4
• Consider bariatric surgery evaluation for patients without contraindications who cannot achieve this degree of weight loss through lifestyle interventions 4

PAP Titration Guidelines

• The American Academy of Sleep Medicine recommends that the NPPV device used for titration should have capability of operating in spontaneous, spontaneous timed, and timed modes 2
• Minimum starting IPAP and EPAP should be 8 cm H2O and 4 cm H2O, respectively 2
• Maximum IPAP should be 30 cm H2O for patients ≥12 years and 20 cm H2O for patients <12 years 2
• Minimum and maximum levels of pressure support are 4 cm H2O and 20 cm H2O, respectively 2
• Increase pressure support if tidal volume is low (<6-8 mL/kg) or if arterial PCO2 remains 10 mm Hg or more above the PCO2 goal for 10 minutes or more 2

Monitoring and Follow-up

• Schedule periodic reassessment appropriate to the stage of disease 1
• Follow-up visits should include monitoring for the development of daytime hypoventilation, which may necessitate around-the-clock ventilation 1

Clinical Considerations and Pitfalls

• Do not use supplemental oxygen alone to treat sleep-related hypoventilation, as this may worsen hypercapnia without addressing the underlying ventilatory problem 1, 6
• Mask displacement can rapidly lead to severe hypoxemia and hypercapnia in fragile patients; additional monitoring such as pulse oximetry is useful 1