CHEST Guidelines-Potential-Effects-of-Hypoxia-Preconditioning-in-Ob

Potential-Effects-of-Hypoxia-Preconditioning-in-Ob

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In a recent correspondence to the Editor of CHEST, Dr. Martin Burtscher responds to an article by Masa et al., which discusses the cardiovascular benefits observed in patients with obesity hypoventilation syndrome (OHS) experiencing severe oxygen desaturation. Burtscher suggests that the terminology and mechanisms discussed need further exploration, particularly in differentiating ischemia preconditioning (IP) from hypoxic preconditioning (HP). He highlights that IP traditionally refers to blood flow restriction, whereas HP, which is applicable to OHS, is induced by repeated hypoxic occurrences due to hypoventilation and can have potential therapeutic applications. He notes that unlike IP, HP is a safer, established method capable of improving exercise tolerance in patients with cardiovascular diseases or COPD.<br /><br />Moreover, Burtscher raises questions about the contrasting impacts of intermittent hypoxia in patients with obstructive sleep apnea (OSA) versus those with OHS, highlighting the maladaptive effects commonly observed in severe OSA. He asks if added daytime hypoxia and hypercapnia in OHS, with extended hypoxia/reoxygenation cycles, might account for the beneficial effects observed.<br /><br />In response, Masa and colleagues clarify their use of the term "ischemia preconditioning," explaining that in OHS, cyclic sympathetic surges result in vasoconstriction leading to reduced blood flow after obstructive events. They propose that myocardial dysfunction could be more pronounced when hypoxia results from combined vasoconstriction and arterial hypoxemia, rather than arterial hypoxemia alone, which is central to their findings. By examining these distinct pathways, they aim to elucidate the cardiovascular mechanisms in OHS, potentially distinguishing them from the maladaptive cycles observed in severe OSA.

Keywords

Obesity Hypoventilation Syndrome

Cardiovascular Benefits

Ischemia Preconditioning

Hypoxic Preconditioning

Intermittent Hypoxia

Obstructive Sleep Apnea

Hypoventilation

Therapeutic Applications

Vasoconstriction

Myocardial Dysfunction