Nitrosative and Oxidative Stress, Reduced Antioxidant Capacity, and Fiber Type Switch in Iron-Deficient COPD Patients: Analysis of Muscle and Systemic Compartments.

We hypothesized that a rise in the levels of oxidative/nitrosative stress markers and a decline in antioxidants might take place in systemic and muscle compartments of chronic obstructive pulmonary disease (COPD) patients with non-anemic iron deficiency. In COPD patients with/without iron depletion (n = 20/group), markers of oxidative/nitrosative stress and antioxidants were determined in blood and vastus lateralis (biopsies, muscle fiber phenotype). Iron metabolism, exercise, and limb muscle strength were assessed in all patients. In iron-deficient COPD compared to non-iron deficient patients, oxidative (lipofuscin) and nitrosative stress levels were greater in muscle and blood compartments and proportions of fast-twitch fibers, whereas levels of mitochondrial superoxide dismutase (SOD) and Trolox equivalent antioxidant capacity (TEAC) decreased. In severe COPD, nitrosative stress and reduced antioxidant capacity were demonstrated in vastus lateralis and systemic compartments of iron-deficient patients. The slow- to fast-twitch muscle fiber switch towards a less resistant phenotype was significantly more prominent in muscles of these patients. Iron deficiency is associated with a specific pattern of nitrosative and oxidative stress and reduced antioxidant capacity in severe COPD irrespective of quadriceps muscle function. In clinical settings, parameters of iron metabolism and content should be routinely quantify given its implications in redox balance and exercise tolerance.

Incidence of pulmonary embolism in patients with non-invasive respiratory support during COVID-19 outbreak.

While the incidence of thrombotic complications in critically ill patients is very high, in patients under non-invasive respiratory support (NIS) is still unknown. The specific incidence of thrombotic events in each of the clinical scenarios within the broad spectrum of severity of COVID-19, is not clearly established, and this has not allowed the implementation of thromboprophylaxis or anticoagulation for routine care in COVID-19. Patients admitted in a semi-critical unit treated initially with NIS, especially Continuous-Positive Airway Pressure (CPAP), were included in the study. The cumulative incidence of pulmonary embolism was analyzed and compared between patients with good response to NIS and patients with clinical deterioration that required orotracheal intubation. 93 patients were included and 16% required mechanical ventilation (MV) after the NIS. The crude cumulative incidence of the PE was 14% (95%, CI 8-22) for all group. In patients that required orotracheal intubation and MV, the cumulative incidence was significantly higher [33% (95%, CI 16-58)] compared to patients that continued with non-invasive support [11% (CI 5-18)] (Log-Rank, p = 0.013). Patients that required mechanical ventilation were at higher risk of PE for a HR of 4.3 (95%CI 1.2-16). In conclusion, cumulative incidence of PE is remarkably higher in critically patients with a potential impact in COVID-19 evolution. In this context, patients under NIS are a very high-risk group for developing PE without a clear strategy regarding thromboprophylaxis.

[Could Inspiratory Muscle Function Be an Equivalent of Lung Hyperinflation in COPD Patients?] / ¿La función muscular inspiratoria podría ser un equivalente de la insuflación pulmonar en los pacientes con EPOC?

Introduction: Chronic obstructive pulmonary disease (COPD) is the respiratory disease that causes the greatest morbidity and mortality worldwide. Lung function parameters and systemic manifestations have been defined as prognostic factors; however, they have limitations. The aim of this study was to analyze whether inspiratory muscle strength could reflect lung hyperinflation, and therefore serve as a prognostic factor in COPD patients. Method: We selected COPD patients who had performed a non-invasive respiratory muscle strength assessment and lung function testing between January 2015 and October 2017. Mortality was subsequently followed up until March 1, 2020. Results: We included 140 COPD patients (GOLD stage I 5%, II 73.4%, and III 21.6%), of whom 10% died during follow-up. Bronchial obstruction, defined by FEV1, was a good predictor of mortality (p = 0.004). Lung hyperinflation, defined as inspiratory capacity (IC)/total lung capacity less than 25 and IC less than 65% of predicted increased mortality in COPD patients (p = 0.001 and p = 0.06, respectively). In this cohort, inspiratory muscle strength, measured by SNIP, was not a prognostic factor (p = 0.629). Conclusion: In COPD patients, lung hyperinflation is a prognostic factor, but inspiratory muscle function is not. Inspiratory muscle function in COPD patients depends not only on lung mechanics but also on intrinsic muscle factors.