From the Research
Sleep apnea primarily causes respiratory acidosis, a type of acid-base imbalance characterized by elevated carbon dioxide levels in the blood. During apneic episodes, breathing temporarily stops or becomes very shallow, leading to decreased ventilation and carbon dioxide retention. This causes the blood pH to decrease as carbon dioxide combines with water to form carbonic acid. In chronic sleep apnea, the body may develop compensatory mechanisms, including renal retention of bicarbonate to partially normalize pH, resulting in a compensated respiratory acidosis. Over time, sleep apnea can also lead to metabolic alkalosis as a secondary compensation. Additionally, the intermittent hypoxia from sleep apnea can cause lactic acid production during episodes, potentially contributing to a mixed acid-base disturbance.
These acid-base imbalances contribute to the cardiovascular complications associated with untreated sleep apnea, including hypertension and arrhythmias. The most recent and highest quality study, 1, found that oxygen therapy and high-flow nasal cannula therapy can effectively reduce the apnea-hypopnea index (AHI) and increase oxyhemoglobin saturation (SpO2) in patients with obstructive sleep apnea. However, treatment with continuous positive airway pressure (CPAP) therapy or other interventions can effectively reverse these acid-base abnormalities by preventing the apneic episodes and normalizing ventilation.
Some key points to consider:
- Sleep apnea can lead to respiratory acidosis, metabolic alkalosis, and mixed acid-base disturbances.
- The intermittent hypoxia from sleep apnea can cause lactic acid production during episodes.
- Treatment with CPAP therapy or other interventions can effectively reverse acid-base abnormalities.
- Oxygen therapy and high-flow nasal cannula therapy can also reduce AHI and increase SpO2 in patients with obstructive sleep apnea, as shown in 1.
- The study 2 highlights the importance of considering different pathophysiological components of sleep-disordered breathing and choosing adequate therapeutic strategies.