What are the best methods for monitoring obesity hypoventilation syndrome (OHS)?

From the Guidelines

Monitoring patients with obesity hypoventilation syndrome (OHS) requires a comprehensive approach that includes regular assessment of respiratory function, sleep quality, and treatment effectiveness, as recommended by the American Thoracic Society clinical practice guideline 1. The best methods for monitoring OHS involve:

• Overnight oximetry or polysomnography every 6-12 months to evaluate nocturnal oxygen saturation and breathing patterns
• Regular arterial blood gas measurements to monitor daytime hypercapnia, with a target PaCO2 below 45 mmHg
• Pulmonary function tests performed annually to assess lung volumes and respiratory muscle strength
• For patients on positive airway pressure therapy, device data should be downloaded monthly to check for mask leaks, compliance, and residual events
• Weight management is crucial, with monthly weight checks and BMI calculations
• Patients should also be monitored for comorbidities including heart failure, pulmonary hypertension, and metabolic disorders through regular echocardiography, BNP levels, and metabolic panels
• Symptom assessment using validated questionnaires like the Epworth Sleepiness Scale helps track improvement in daytime somnolence This approach is supported by the American Thoracic Society clinical practice guideline, which suggests that clinicians use a serum bicarbonate level < 27 mmol/L to exclude the diagnosis of OHS in obese patients with sleep-disordered breathing when suspicion for OHS is not very high (< 20%) but to measure arterial blood gases in patients strongly suspected of having OHS 1. Additionally, the guideline recommends that stable ambulatory patients with OHS receive positive airway pressure (PAP) therapy, and that continuous positive airway pressure (CPAP) rather than noninvasive ventilation be offered as the first-line treatment to stable ambulatory patients with OHS and coexistent severe obstructive sleep apnea 1. The guideline also suggests that patients hospitalized with respiratory failure and suspected of having OHS be discharged with noninvasive ventilation until they undergo outpatient diagnostic procedures and PAP titration in the sleep laboratory, ideally within 2-3 months 1. Overall, a comprehensive monitoring approach is necessary to manage OHS effectively and prevent progressive respiratory failure, as supported by the American Thoracic Society clinical practice guideline 1 and other studies 1.

From the Research

Monitoring Obesity Hypoventilation Syndrome (OHS)

The best methods for monitoring OHS include:

• Arterial blood gas measurements to assess daytime hypercapnia [(2,3,4)]
• Sleep studies, such as polysomnography, to evaluate sleep-disordered breathing [(2,3,4)]
• Assessment of clinical symptoms, such as sleepiness and quality of life [(3,4)]
• Evaluation of comorbidities, including metabolic and cardiovascular conditions 3

Treatment and Monitoring

Treatment of OHS typically involves the use of non-invasive positive airway pressure, including:

• Continuous positive airway pressure (CPAP) for patients with concomitant severe obstructive sleep apnea [(2,3,5)]
• Non-invasive ventilation (NIV) for patients with hypoventilation during sleep and no or milder forms of obstructive sleep apnea [(2,3,4)]
• Monitoring of treatment efficacy, including assessment of arterial blood gases, sleep studies, and clinical symptoms [(4,5)]

Key Considerations

Key considerations in monitoring OHS include:

• The presence of daytime hypercapnia and sleep-disordered breathing [(2,3)]
• The effectiveness of treatment in improving clinical symptoms, quality of life, and gas exchange [(3,4)]
• The importance of managing comorbidities, including metabolic and cardiovascular conditions 3