The Interpretation of Arterial Blood Gas During the Apneic Phase of a Patient With Obstructive Sleep Apnea: A Case Report

Obstructive sleep apnea (OSA) is now increasingly recognized as a disease entity that can play a major role in affecting multiple organ systems. Even though the symptoms of OSA were first described in the 19th century as Pickwickian syndrome, there are a lot of things that came to be known only recently including its pathophysiology and diagnosis. In this case report, we present some findings that mostly have not been reported in OSA patients before. It has been reported that OSA patients have a typical arterial blood gas (ABG) picture of raised bicarbonate (HCO(3)-) levels, which also aid in adding to the diagnosis, but we found some more findings that are only specific to the apneic phase of the disease. A 65-year-old female patient was put on a ventilator due to dengue-associated acute respiratory distress syndrome (ARDS). She was also diagnosed with obstructive sleep apnea after facing difficulty in weaning from a ventilator. Post extubation, she was put on noninvasive ventilation (NIV), but the patient's arterial blood gas (ABG) drawn during the apneic phase was showing signs of severe metabolic acidosis even on NIV. This was reversible and gets corrected once the patient is awakened or put on NIV. Clinical decisions from ABG in a patient with OSA may result in errors especially when the ABG is drawn during the apneic phase of the disease. Clinicians have to be careful of this phenomenon, and more research needs to be undertaken to fully understand the pathophysiology of this phenomenon.