Supplemental Oxygen Therapy in Obesity Hypoventilation Syndrome

Introduction to Oxygen Supplementation

• The American Thoracic Society guidelines acknowledge the complexity of adding oxygen to PAP therapy in patients with persistent hypoxemia despite PAP optimization, but do not provide a formal recommendation 2, 3, 4, 5

Critical Safety Principles

• Oxygen alone is dangerous in OHS because it can correct hypoxemia without treating the underlying hypoventilation, potentially impairing central respiratory drive and worsening CO2 retention 1

Step-by-Step Algorithm for Oxygen Supplementation

• Verify adequate adherence to therapy, as higher adherence correlates with better respiratory control, according to the American Journal of Respiratory and Critical Care Medicine 6
• Consider that high CPAP pressures may be needed in OHS patients, as noted in Thorax 7
• Monitor both SpO2 AND CO2 levels continuously through blood gas sampling or capnography 1

Monitoring Requirements When Oxygen is Added

• Continuously monitor oxygen saturation AND carbon dioxide levels, and assess whether hypoxemia is due to hypoventilation, atelectasis, or airway secretions, treating the underlying cause appropriately rather than masking it with oxygen 1
• Follow up within 4-8 weeks to assess clinical and physiological response, as recommended by the American Journal of Respiratory and Critical Care Medicine 6

Postoperative Context

• In the perioperative setting for bariatric surgery patients, supplemental oxygen can be given via the patient's CPAP machine or via nasal cannula under the CPAP mask, as described in Anaesthesia 8
• Non-invasive positive pressure (CPAP or BiPAP) with or without supplemental oxygen should be used liberally for hypoxemia (SpO2 <90%) in the immediate postoperative period, according to the World Journal of Emergency Surgery 9