CHEST Guidelines-Response_chest

Response_chest_14 (3)

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The document discusses the relationship between obstructive sleep apnea (OSA) and cardiovascular pathophysiology, with a specific focus on its implications for obesity hypoventilation syndrome (OHS). Dr. Giorgio Castellana and colleagues from the University of Bari raise the question of whether findings pertaining to OSA can be applied to OHS. They are interested in exploring the role of nocturnal hypoventilation in patients with OHS, especially those with severe OSA and high body mass index (BMI), who may experience sustained hypoxia between apneic events.<br /><br />Dr. Juan F. Masa and colleagues, responding to Castellana, acknowledge the importance of distinguishing the effects of intermittent versus sustained hypoxemia on cardiovascular outcomes. They highlight that their dataset linked the severity of OSA and measures of intermittent hypoxemia, such as the oxygen desaturation index, with reduced cardiovascular morbidity. However, sustained hypoxemia, which was evaluated through daytime PaO2 and the percentage of total sleep time with oxygen saturation below 90%, was not associated with a reduction in cardiovascular morbidities.<br /><br />The response suggests a complex interaction where sustained hypoxemia may have a potential protective cardiovascular role if its influence is greater than that of intermittent hypoxemia. The implication is that patients with OHS who demonstrate persistent hypoxemia, regardless of OSA severity, might not exhibit the same cardiovascular protection seen in those with predominant intermittent hypoxemia.<br /><br />Lastly, an introduction of high-sensitivity cardiac troponin T as a potential biomarker for assessing OSA-related cardiovascular morbidity in OHS patients is briefly mentioned, indicating a direction for future research in understanding these pathophysiological interactions. This exchange underscores the need for further studies to elucidate the complex relationships between these sleep-related disorders and cardiovascular outcomes.

Keywords

obstructive sleep apnea

cardiovascular pathophysiology

obesity hypoventilation syndrome

nocturnal hypoventilation

sustained hypoxemia

intermittent hypoxemia

oxygen desaturation index

high body mass index

cardiovascular morbidity

cardiac troponin T