Hypoxic burden and sleep hypoventilation in obese patients.

INTRODUCTION: Novel biomarkers of hypoxic load have emerged, as sleep apnea-specific hypoxic burden which provides more precise assessment of intermittent hypoxemia severity. Our main objective was to assess the potential benefit of hypoxic burden to identify obesity-related sleep hypoventilation. We hypothesized that hypoxic burden may help diagnose obesity-related sleep hypoventilation better than usual sleep respiratory measures (i.e., apnea-hypopnea index (AHI), mean SpO2, time with SpO2 < 90 %). METHODS: This retrospective study was conducted from June 2022 to October 2023 at the University Hospital of Rouen, France. All consecutive obese patients (BMI ≥30 kg/m2), adults, with no other respiratory or neurological diseases who underwent a polysomnography or polygraphy with concomitant capnography were included. Sleep hypoventilation was defined according to American Academy of Sleep Medicine criteria based on transcutaneous CO2 monitoring (PtcCO2). Diagnostic performance of sleep-related respiratory measures i.e., sleep apnea-specific hypoxic burden, apnea-hypopnea index (AHI), mean SpO2, time with SpO2 < 90 % was evaluated using Receiver Operating Characteristic (ROC) curves. Correlations between sleep-related respiratory measures were assessed by a Spearman correlation matrix. RESULTS: Among 107 obese patients with analyzed capnography, 37 (35 %) had sleep hypoventilation. Patients were 53 ± 14 years old, mean BMI = 38 ± 6 kg/m2, mean AHI = 26.5 ± 25/h, mean hypoxic burden = 67 ± 109 %min/h, mean SpO2 = 91.5 ± 3 %, mean time with SpO2<90 % = 19.4 ± 28 %, mean PtcCO2 = 6.2 ± 0.7 kPa. A low positive correlation was found between hypoxic burden and mean PtcCO2 (r = 0.4, p < 0.001). Multivariate logistic regression model explaining sleep hypoventilation was insufficient with area under ROC curve of hypoxic burden estimated at 0.74 (95 % CI 0.65 to 0.84). CONCLUSION: Hypoxic burden has low correlation with transcutaneous CO2 pressure and a low ability to diagnose obesity-related sleep hypoventilation.

[High-flow nasal oxygen therapy and hypercapnic acute respiratory failure]. / Oxygénothérapie nasale à haut débit et insuffisance respiratoire aiguë hypercapnique.

Humidified high-flow nasal oxygen therapy (HFNO) has, in recent years, come to assume a key role in the management of hypoxemic acute respiratory failure (ARF). While non-invasive ventilation (NIV) currently represents the first-line ventilatory strategy in patients exhibiting hypercapnic ARF, the operating principles and physiological effects of HFNO could be interesting and useful in the initial management of hypercapnic ARF and/or after extubation, particularly in acute exacerbations of chronic obstructive pulmonary disease. Under these conditions, HFNO could be used either alone continuously or in combination with NIV during breaks in spontaneous breathing, depending on the severity and etiology of the underlying hypercapnic ARF.

[Ventilatory management of SARS-CoV-2 acute respiratory failure]. / Prise en charge ventilatoire de l'insuffisance respiratoire aiguë à SARS-CoV-2.

COVID-19 pneumonia presents several particularities in its clinical presentation (cytokine storm, silent hypoxemia, thrombo-embolic risk) and may lead to a number of acute respiratory distress syndrome (ARDS) phenotypes. While the optimal oxygenation strategy in cases of hypoxemic acute respiratory failure (ARF) is still under debate, ventilatory management of COVID-19-related ARF has confirmed the efficacy of high-flow oxygen therapy and restored interest in other ventilatory approaches such as continuous positive airway pressure (CPAP) and noninvasive ventilation involving a helmet, which due to patient overflow are sometimes implemented outside of critical care units. However, further studies are still needed to determine which patients should be given which oxygenation technique, and under which conditions they require invasive mechanical ventilation, given that delayed initiation potentially burdens prognosis. During invasive mechanical ventilation, ventral decubitus and extracorporeal membrane oxygenation have become increasingly prevalent. While innovative therapies such as awake prone position or lung transplantation have likewise been developed, their indications, modalities and efficacy remain to be determined.

NRF2 targeting: a promising therapeutic strategy in chronic obstructive pulmonary disease.

Several convergent destructive mechanisms such as oxidative stress, alveolar cell apoptosis, extracellular matrix proteolysis and chronic inflammation contribute to chronic obstructive pulmonary disease (COPD) development. Evidence suggests that oxidative stress contributes to the pathophysiology of COPD, particularly during exacerbations. Nuclear factor erythroid-2-related factor 2 (NRF2), a transcription factor expressed predominantly in epithelium and alveolar macrophages, has an essential protective role in the lungs through the activation of antioxidant response element-regulated antioxidant and cytoprotective genes. Animal models and human studies have identified NRF2 and several NRF2 target genes as a protective system against inflammation and oxidative stress from cigarette smoke, a major causative factor in COPD development. Hence, NRF2 targeting might provide clinical benefit by reducing both oxidative stress and inflammation in COPD.