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We assessed the speed of the ventilatory response to square-wave changes in alveolar PCO2 and the relative gains of the steady-state ventilatory response to CO2 of the central chemoreceptors vs. the carotid body chemoreceptors in intact, unanesthetized dogs. We used extracorporeal perfusion of the reversibly isolated carotid sinus to maintain normal tonic activity of the carotid body chemoreceptor while preventing it from sensing systemic changes in CO2, thereby allowing us to determine the response of the central chemoreceptors alone. We found the following. 1) The ventilatory response of the central chemoreceptors alone is l1.2 (SD = 3.6) s slower than when carotid bodies are allowed to sense CO2 changes. 2) On average, the central chemoreceptors contribute ∼63% of the gain to steady-state increases in CO2. There was wide dog-to-dog variability in the relative contributions of central vs. carotid body chemoreceptors; the central exceeded the carotid body gain in four of six dogs, but in two dogs carotid body gain exceeded central CO2 gain. If humans respond similarly to dogs, we propose that the slower response of the central chemoreceptors vs. the carotid chemoreceptors prevents the central chemoreceptors from contributing significantly to ventilatory responses to rapid, transient changes in arterial PCO2 such as those after periods of hypoventilation or hyperventilation (‘ventilatory undershoots or overshoots’) observed during sleep-disordered breathing. However, the greater average responsiveness of the central chemore-ceptors to brain hypercapnia in the steady-state suggests that these receptors may contribute significantly to ventilatory overshoots once unstable/periodic breathing is fully established. [ABSTRACT FROM AUTHOR]

A letter to the editor is presented in response to the article "Endogenous preoptic hydrogen sulphide attenuates hypoxia-induced hyperventilation," by M. Kwiatkoski and colleagues in the 2013 issue.

Introduction: Cardiopulmonary resuscitation (CPR) in microgravity requires specific methods to counteract weightlessness. Automatic chest compression devices (ACCDs) could improve CPR in microgravity. We aimed to compare ACCDs versus manual CPR in microgravity simulated through parabolic flights., Methods: This prospective, open, controlled study compared 3 ACCDs (LUCAS 3©, AUTOPULSE©, EASYPULSE©) to manual CPR during the 66th CNES (Centre National d'Etudes Spatiales) parabolic flights campaign onboard the Novespace Air Zero-G A310 aircraft. Chest compression depths and rates were monitored by a Laerdal© Resusci-Ann-QCPR manikin., Results: The LUCAS 3© device had a median compression depth of 53.0 [53.0-54.0] mm, significantly higher than the EASYPULSE©, AUTOPULSE©, and Manual CPR (Handstand method), measured at 29.0 [26.0-32.0] mm, 29.0 [27.5-30.7] mm and 34.5 [29.6-43.3] mm, respectively (p value < 0.001). Compression rates were 101 [101-101], 100 [100-100] and 80 [80-80] compressions per minute (cpm) for the LUCAS 3©, EASYPULSE©, and AUTOPULSE©, respectively. Manual CPR provided a significantly higher compression rate with 115 [109-123] cpm (p value < 0.001)., Conclusion: Only LUCAS 3© provided effective CPR according to international guidelines. ACCDs should implement microgravity CPR algorithms., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Background: Assessment of the athlete's heart is challenging because of a phenotypic overlap between reactive physiological adaptation and pathological remodelling. The potential value of myocardial deformation remains controversial in identifying early cardiomyopathy., Aim: To identify the echocardiographic phenotype of athletes using advanced two-dimensional speckle tracking imaging, and to define predictive factors of subtle left ventricular systolic dysfunction., Methods: In total, 191 healthy male athletes who underwent a preparticipation medical evaluation at Nancy University Hospital between 2013 and 2020 were included. Clinical and echocardiographic data were compared with 161 healthy male subjects from the STANISLAS cohort. Borderline global longitudinal strain value was defined as<17.5%., Results: Athletes demonstrated lower left ventricular ejection fraction (57.9±5.3% vs. 62.6±6.4%; P<0.01) and lower global longitudinal strain (17.5±2.2% vs. 21.1±2.1%; P<0.01). No significant differences were found between athletes with and without a borderline global longitudinal strain value regarding clinical characteristics, structural echocardiographic features and exercise capacity. A borderline global longitudinal strain value was associated with a lower endocardial global longitudinal strain (18.8±1.2% vs. 22.7±1.9%; P=0.02), a lower epicardial global longitudinal strain (14.0±1.1% vs. 16.6±1.2%; P<0.01) and a higher endocardial/epicardial global longitudinal strain ratio (1.36±0.07 vs. 1.32±0.06; P<0.01). No significant difference was found regarding mechanical dispersion (P=0.46)., Conclusions: Borderline global longitudinal strain value in athletes does not appear to be related to structural remodelling, mechanical dispersion or exercise capacity. The athlete's heart is characterized by a specific myocardial deformation pattern with a more pronounced epicardial layer strain impairment., (Copyright © 2024 Elsevier Masson SAS. All rights reserved.)

Introduction: Chronic wound care remains a critical public health challenge in terms of prevalence, quality of life and healthcare costs on a global scale. Currently used methods to assess the size and content of wounds include direct contact techniques based on double-layer film, ruler measurements, digital photography and visual examination. Nowadays, despite these evaluations, close monitoring and tracking of these chronic wounds remain a great challenge. The use of telemonitoring through digital measurement tools may offer a potential means of improving healing management processes. Many studies have evaluated the size and content of the wound through digital devices such as mobile phones and computers. However, the clinical accuracy of these tools remains to be clarified. The objective of this systematic review is to assess and consolidate the current state-of-the-art digital devices for both quantitative (length, width, surface area, perimeter, volume and depth) and qualitative (granulation, fibrin, necrosis and slough) indicators of wound care., Methods and Analysis: We will include studies using digital measurement methods from databases such as EBSCO, Cochrane Library, MEDLINE, Web of Science and EMBASE, limited to French and English publications until November 15, 2023. Following the Preferred Reporting Items for Systematic Review and Meta-Analysis guidelines, selection involves two independent reviewers conducting title and abstract screenings, study selections, data extractions and risk-of-bias assessments using QUADAS-2. Discrepancies will be resolved through discussion or a third reviewer., Ethics and Dissemination: Primary data will not be collected in this study; thus, ethical approval will not be required. The study's findings will be published in a peer-reviewed journal., Prospero Registration Number: CRD42023396642., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2024. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)