Pub Date : 2026-04-01Epub Date: 2025-12-22DOI: 10.1016/j.resp.2025.104530
M. Berger , E. Leusmann , T. Senfter , A.-S. Käferböck , M. Wald , M. Pillei
Continuous positive airway pressure (CPAP) technology is crucial in the initial respiratory support of newborns with insufficient spontaneous breathing. Although two neonatal CPAP systems, the Neopuff T-piece and the Inspire rPAP, use constant flow technology, clinical observations reveal significant differences in pressure stability during ventilation of newborn children. The Neopuff T-piece device exhibits stronger pressure fluctuations compared to the Inspire rPAP, which maintains more stable airway pressures. This study investigates the root causes of these instabilities using computational fluid dynamics (CFD) simulations in anatomically realistic neonatal airway models, focusing on how device geometry and flow behavior influence pressure stability and imposed work of breathing (iWOB). Digital models of the devices were created using CAD software, and neonatal airway geometries were segmented from MRI data. Steady-state 3D CFD simulations, employing the k-ω-SST turbulence model, were conducted for three respiratory scenarios: resting, inhalation, and exhalation. Both CPAP devices were simulated under identical boundary conditions for direct comparison. The Inspire rPAP demonstrated higher static pressures, flow velocities, and turbulent kinetic energy (TKE) but maintained superior pressure stability, with fluctuations limited to 6.28 %, compared to 46.12 % for the Neopuff. The Neopuff’s T-piece geometry generated vortices and flow resistance, particularly during exhalation, increasing iWOB. In contrast, the Inspire rPAP’s narrower, multi-channel design effectively shielded the patient interface from high-energy flows, reducing interaction with expiratory streams. These findings highlight the critical role of internal flow-guiding geometry in pressure regulation and iWOB. The study underscores the value of CFD modeling in optimizing neonatal CPAP systems to improve respiratory support and reduce the burden on preterm infants.
{"title":"Dynamics analysis of neonatal CPAP devices neopuff and inspire rPAP: Investigating pressure stability and work of breathing in anatomically realistic airway models","authors":"M. Berger , E. Leusmann , T. Senfter , A.-S. Käferböck , M. Wald , M. Pillei","doi":"10.1016/j.resp.2025.104530","DOIUrl":"10.1016/j.resp.2025.104530","url":null,"abstract":"<div><div>Continuous positive airway pressure (CPAP) technology is crucial in the initial respiratory support of newborns with insufficient spontaneous breathing. Although two neonatal CPAP systems, the Neopuff T-piece and the Inspire rPAP, use constant flow technology, clinical observations reveal significant differences in pressure stability during ventilation of newborn children. The Neopuff T-piece device exhibits stronger pressure fluctuations compared to the Inspire rPAP, which maintains more stable airway pressures. This study investigates the root causes of these instabilities using computational fluid dynamics (CFD) simulations in anatomically realistic neonatal airway models, focusing on how device geometry and flow behavior influence pressure stability and imposed work of breathing (iWOB). Digital models of the devices were created using CAD software, and neonatal airway geometries were segmented from MRI data. Steady-state 3D CFD simulations, employing the k-ω-SST turbulence model, were conducted for three respiratory scenarios: resting, inhalation, and exhalation. Both CPAP devices were simulated under identical boundary conditions for direct comparison. The Inspire rPAP demonstrated higher static pressures, flow velocities, and turbulent kinetic energy (TKE) but maintained superior pressure stability, with fluctuations limited to 6.28 %, compared to 46.12 % for the Neopuff. The Neopuff’s T-piece geometry generated vortices and flow resistance, particularly during exhalation, increasing iWOB. In contrast, the Inspire rPAP’s narrower, multi-channel design effectively shielded the patient interface from high-energy flows, reducing interaction with expiratory streams. These findings highlight the critical role of internal flow-guiding geometry in pressure regulation and iWOB. The study underscores the value of CFD modeling in optimizing neonatal CPAP systems to improve respiratory support and reduce the burden on preterm infants.</div></div>","PeriodicalId":20961,"journal":{"name":"Respiratory Physiology & Neurobiology","volume":"341 ","pages":"Article 104530"},"PeriodicalIF":1.6,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145808338","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-04-01Epub Date: 2025-12-22DOI: 10.1016/j.resp.2025.104531
Volodymyr Portnichenko , Roman Yanko , Petro Tsapenko , Mikhail Levashov , Iryna Litovka , Mykola Zavhorodnii , Mieczyslaw Pokorski
Burn disease, which is a sequel of skin burn injuries, is a common cause of complications and the development of associated pathologies. This study aimed to assess the effects of burn disease on the lungs and their correction with melatonin. We used a standard skin 14-day burn model in Wistar rats. During burn progression, phase changes in metabolism were noted from a hypometabolic phase in the first 4 days to a hypermetabolic phase starting on Day 5. By Day 14, the energy metabolism had normalized to the control level. In experimental melatonin burn treatment, a hypermetabolic response was noted during the first 3 days. By Day 10, the ventilatory response decreased below the baseline level, and by Day 14, it did not significantly differ from that in the control group. Morphological changes in the lungs of rats with burn injuries were characterized by structural alterations, such as reduced functional activity, decreased air permeability, and suppression of gas exchange processes. In rats receiving melatonin alongside burn injury, most morphological lung indicators remained at control levels. We conclude that melatonin treatment accelerates healing and reduces complications associated with burn injuries.
{"title":"Metabolism and respiration in skin burn injury in rats: Corrective effects of melatonin","authors":"Volodymyr Portnichenko , Roman Yanko , Petro Tsapenko , Mikhail Levashov , Iryna Litovka , Mykola Zavhorodnii , Mieczyslaw Pokorski","doi":"10.1016/j.resp.2025.104531","DOIUrl":"10.1016/j.resp.2025.104531","url":null,"abstract":"<div><div>Burn disease, which is a sequel of skin burn injuries, is a common cause of complications and the development of associated pathologies. This study aimed to assess the effects of burn disease on the lungs and their correction with melatonin. We used a standard skin 14-day burn model in Wistar rats. During burn progression, phase changes in metabolism were noted from a hypometabolic phase in the first 4 days to a hypermetabolic phase starting on Day 5. By Day 14, the energy metabolism had normalized to the control level. In experimental melatonin burn treatment, a hypermetabolic response was noted during the first 3 days. By Day 10, the ventilatory response decreased below the baseline level, and by Day 14, it did not significantly differ from that in the control group. Morphological changes in the lungs of rats with burn injuries were characterized by structural alterations, such as reduced functional activity, decreased air permeability, and suppression of gas exchange processes. In rats receiving melatonin alongside burn injury, most morphological lung indicators remained at control levels. We conclude that melatonin treatment accelerates healing and reduces complications associated with burn injuries.</div></div>","PeriodicalId":20961,"journal":{"name":"Respiratory Physiology & Neurobiology","volume":"341 ","pages":"Article 104531"},"PeriodicalIF":1.6,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145828036","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-04-01Epub Date: 2025-12-17DOI: 10.1016/j.resp.2025.104529
Michael L. Frazure , Emily G. Flanigan , Ralph F. Fregosi
We tested the hypothesis that developmental nicotine exposure (DNE) disrupts the cardiorespiratory response to brief, severe hypoxia by measuring ventilatory and heart rate during a 15 s epoch of N2 breathing in one-to-six-day-old Sprague Dawley rat pups. Data were analyzed with a 3-way ANOVA, with inspired O2 concentration, treatment group and sex the main factors. As expected, N2 breathing significantly increased the inspired pulmonary ventilation rate () in control pups of both sexes, driven by an increase of tidal volume. In contrast, neither male nor female DNE pups increased during the N2 challenge. There was no effect of hypoxia on heart rate in any group. These findings reveal a selective vulnerability: DNE specifically compromises the respiratory system’s ability to increase ventilation in response to brief severe hypoxia. This dissociation between ventilatory and heart rate responses to severe hypoxia provides fresh insight into the impact of DNE on cardiorespiratory function during a critical developmental stage.
{"title":"Developmental nicotine exposure eliminates the ventilatory response to a brief episode of severe hypoxia, independently of sex","authors":"Michael L. Frazure , Emily G. Flanigan , Ralph F. Fregosi","doi":"10.1016/j.resp.2025.104529","DOIUrl":"10.1016/j.resp.2025.104529","url":null,"abstract":"<div><div>We tested the hypothesis that developmental nicotine exposure (DNE) disrupts the cardiorespiratory response to brief, severe hypoxia by measuring ventilatory and heart rate during a 15 s epoch of N<sub>2</sub> breathing in one-to-six-day-old Sprague Dawley rat pups. Data were analyzed with a 3-way ANOVA, with inspired O<sub>2</sub> concentration, treatment group and sex the main factors. As expected, N<sub>2</sub> breathing significantly increased the inspired pulmonary ventilation rate (<span><math><mover><mi>V</mi><mo>˙</mo></mover></math></span>) in control pups of both sexes, driven by an increase of tidal volume. In contrast, neither male nor female DNE pups increased <span><math><mrow><mover><mrow><mi>V</mi></mrow><mo>̇</mo></mover><mspace></mspace></mrow></math></span> during the N<sub>2</sub> challenge. There was no effect of hypoxia on heart rate in any group. These findings reveal a selective vulnerability: DNE specifically compromises the respiratory system’s ability to increase ventilation in response to brief severe hypoxia. This dissociation between ventilatory and heart rate responses to severe hypoxia provides fresh insight into the impact of DNE on cardiorespiratory function during a critical developmental stage.</div></div>","PeriodicalId":20961,"journal":{"name":"Respiratory Physiology & Neurobiology","volume":"341 ","pages":"Article 104529"},"PeriodicalIF":1.6,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145794640","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The essential role of upper airway muscles in maintaining patency has led to the hypothesis that alterations in tongue muscle properties may contribute to the development of obstructive sleep apnea (OSA). Prior studies comparing the mechanical characteristics of tongue muscles in OSA patients and healthy controls have yielded inconsistent results. In this study, we evaluated tongue muscle mechanics using an objective, non-volitional method: surface electrical stimulation of the genioglossus (GG) muscle. Tongue protrusion force, whether generated volitionally or by electrical stimulation, was significantly lower in OSA patients. Stimulated force was consistently lower than volitional force across all participants; however, the two measures were strongly correlated (r = 0.62, p < 0.001). Tongue muscle fatigability in OSA patients did not differ significantly from controls during volitional testing or low-frequency stimulation but was increased during high-frequency stimulation. Twitch contraction and half-relaxation times, as well as high-to-low frequency force curves, were comparable between OSA and control subjects. These findings indicate that although tongue muscle fiber composition appears similar in OSA and control groups, maximal tongue protrusion force is reduced in OSA. Given the inconsistent results of prior studies, we suggest that the methodology of force assessment may be critical: different testing modes likely recruit distinct patterns of tongue muscle coordination and may uncover coordination deficits in OSA. Furthermore, the increased fatigability observed during high-frequency stimulation is consistent with the presence of tongue muscle neuropathy in this population.
上气道肌肉在维持气道通畅方面的重要作用使得舌肌特性的改变可能导致阻塞性睡眠呼吸暂停（OSA）的发生。先前的研究比较了OSA患者和健康对照者舌肌的力学特性，结果并不一致。在这项研究中，我们评估舌肌力学使用客观的，非意志的方法：颏舌肌（GG）的表面电刺激。在OSA患者中，无论是自愿还是电刺激产生的舌突力都明显降低。在所有参与者中，受刺激的力量始终低于意志力量；然而，这两种测量结果是强相关的（r = 0.62, p < 0.001）。在意志测试或低频刺激时，OSA患者的舌肌疲劳与对照组无显著差异，但在高频刺激时，舌肌疲劳有所增加。抽搐收缩和半松弛时间以及高低频力曲线在OSA和对照组之间具有可比性。这些发现表明，尽管OSA组和对照组的舌肌纤维组成相似，但OSA组的最大舌突力有所降低。鉴于之前的研究结果不一致，我们认为力评估的方法可能是至关重要的：不同的测试模式可能会招募不同的舌肌协调模式，并可能发现OSA的协调缺陷。此外，在高频刺激期间观察到的疲劳增加与该人群中舌肌神经病变的存在是一致的。
{"title":"Neurophysiologic tongue protrusion characteristics$ in obstructive sleep apnea: A comparative study","authors":"Ron Oliven , Arie Oliven , Mostafa Somri , Emilia Hardak , Naveh Tov","doi":"10.1016/j.resp.2026.104544","DOIUrl":"10.1016/j.resp.2026.104544","url":null,"abstract":"<div><div>The essential role of upper airway muscles in maintaining patency has led to the hypothesis that alterations in tongue muscle properties may contribute to the development of obstructive sleep apnea (OSA). Prior studies comparing the mechanical characteristics of tongue muscles in OSA patients and healthy controls have yielded inconsistent results. In this study, we evaluated tongue muscle mechanics using an objective, non-volitional method: surface electrical stimulation of the genioglossus (GG) muscle. Tongue protrusion force, whether generated volitionally or by electrical stimulation, was significantly lower in OSA patients. Stimulated force was consistently lower than volitional force across all participants; however, the two measures were strongly correlated (r = 0.62, p < 0.001). Tongue muscle fatigability in OSA patients did not differ significantly from controls during volitional testing or low-frequency stimulation but was increased during high-frequency stimulation. Twitch contraction and half-relaxation times, as well as high-to-low frequency force curves, were comparable between OSA and control subjects. These findings indicate that although tongue muscle fiber composition appears similar in OSA and control groups, maximal tongue protrusion force is reduced in OSA. Given the inconsistent results of prior studies, we suggest that the methodology of force assessment may be critical: different testing modes likely recruit distinct patterns of tongue muscle coordination and may uncover coordination deficits in OSA. Furthermore, the increased fatigability observed during high-frequency stimulation is consistent with the presence of tongue muscle neuropathy in this population.</div></div>","PeriodicalId":20961,"journal":{"name":"Respiratory Physiology & Neurobiology","volume":"341 ","pages":"Article 104544"},"PeriodicalIF":1.6,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145990159","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-03-16DOI: 10.1016/j.resp.2026.104564
Wioleta Rosa, Rafal Pilinski, Robert Baranski, Mateusz Stec, Agnieszka Sliwka
Intensified inspiration and expiration require recruitment of accessory respiratory muscles, whose activity is essential for generating appropriate pressure changes and ensuring efficient ventilation. The aim of this study was to evaluate their surface activity (sEMG) and analyze bilateral symmetry and coordination in healthy individuals during maximal inspiratory (PImax) and expiratory (PEmax) pressure maneuvers. Thirty healthy volunteers (mean age 49 ± 12 years) participated in the study. sEMG activity was recorded from the sternocleidomastoid (SCM), scalene (SCA), and external oblique abdominal (EOA) muscles. Signals were normalized to maximal voluntary contraction (%MVC). Bilateral symmetry and agonist-antagonist activity ratios were assessed. High bilateral symmetry was observed for all examined muscles (p > 0.05 for all R/L pairs). The greatest activity was noted for the EOA during forced expiration, reaching 100.74% MVC, whereas SCM and SCA exhibited peak activity during inspiration (53.23% MVC and 40.18% MVC, respectively). Coordination analysis revealed significant agonist dominance; however, the EOA maintained relatively higher activity during the antagonist phase (inspiration) compared to neck muscles during expiration. No significant correlations were found between PImax/PEmax values and sEMG activity of the accessory muscles. In healthy individuals, accessory respiratory muscles function with high bilateral symmetry. The EOA is a key force generator during forced expiration, likely contributing to trunk stabilization. The absence of a relationship between sEMG activity and generated pressure suggests that inspiratory and expiratory force in healthy subjects depends on mechanisms more complex than mere recruitment of accessory muscle motor units.
{"title":"Electromyographic activity and coordination of accessory respiratory muscles during increased breathing effort in healthy adults.","authors":"Wioleta Rosa, Rafal Pilinski, Robert Baranski, Mateusz Stec, Agnieszka Sliwka","doi":"10.1016/j.resp.2026.104564","DOIUrl":"10.1016/j.resp.2026.104564","url":null,"abstract":"<p><p>Intensified inspiration and expiration require recruitment of accessory respiratory muscles, whose activity is essential for generating appropriate pressure changes and ensuring efficient ventilation. The aim of this study was to evaluate their surface activity (sEMG) and analyze bilateral symmetry and coordination in healthy individuals during maximal inspiratory (PImax) and expiratory (PEmax) pressure maneuvers. Thirty healthy volunteers (mean age 49 ± 12 years) participated in the study. sEMG activity was recorded from the sternocleidomastoid (SCM), scalene (SCA), and external oblique abdominal (EOA) muscles. Signals were normalized to maximal voluntary contraction (%MVC). Bilateral symmetry and agonist-antagonist activity ratios were assessed. High bilateral symmetry was observed for all examined muscles (p > 0.05 for all R/L pairs). The greatest activity was noted for the EOA during forced expiration, reaching 100.74% MVC, whereas SCM and SCA exhibited peak activity during inspiration (53.23% MVC and 40.18% MVC, respectively). Coordination analysis revealed significant agonist dominance; however, the EOA maintained relatively higher activity during the antagonist phase (inspiration) compared to neck muscles during expiration. No significant correlations were found between PImax/PEmax values and sEMG activity of the accessory muscles. In healthy individuals, accessory respiratory muscles function with high bilateral symmetry. The EOA is a key force generator during forced expiration, likely contributing to trunk stabilization. The absence of a relationship between sEMG activity and generated pressure suggests that inspiratory and expiratory force in healthy subjects depends on mechanisms more complex than mere recruitment of accessory muscle motor units.</p>","PeriodicalId":20961,"journal":{"name":"Respiratory Physiology & Neurobiology","volume":" ","pages":"104564"},"PeriodicalIF":1.6,"publicationDate":"2026-03-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147481492","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-03-16DOI: 10.1016/j.resp.2026.104565
Leandro da Silva Cândido, Matheus Ramos Lopes, Pedro Alves Machado-Junior, Aline Maria Dos Santos, Thais Lopes Valetim Di Paschoale Ostolin, Ana Beatriz Farias de Souza, Alexandre Barbosa Reis, Fernanda Cacilda Dos Santos Silva, Deoclécio Alves Chianca-Jr, Frank Silva Bezerra, Rodrigo Cunha Alvim de Menezes
Background: Mechanical ventilation is an essential intervention for patients with acute respiratory failure. However, ventilatory strategies with high tidal volumes can be harmful, and are strongly associated with ventilator-induced lung injury. Growing evidence suggests that ventilator-induced lung injury may also trigger oxidative stress and contribute to systemic inflammation and neuronal impairment, particularly in regions such as the hippocampus, which plays a fundamental role in cognitive functions.
Objective: Investigate the impact of high tidal volume mechanical ventilation on anxiety-related behaviors, memory, inflammation, and oxidative stress in the central nervous system of male Wistar rats.
Methods: Animals were assigned to three groups: spontaneous ventilation, mechanical ventilation with 6mL/kg, and mechanical ventilation with 12mL/kg. Ventilated animals underwent volume-controlled ventilation for 180minutes.
Results: Our findings showed that high tidal volume ventilation led to a marked influx of inflammatory cells, increased oxidative stress, and structural damage in the lungs. These pulmonary alterations were accompanied by elevated levels of oxidative markers and pro-inflammatory cytokines in the hippocampus and amygdala. Ventilated animals showed significant deficits in memory-related tasks, and increased anxiety related behaviors.
Conclusion: The relationship between oxidative stress, neuroinflammation, and behavioral changes validates the hypothesis that the ventilator-induced lung injury effects extend beyond the lungs, impairing brain function and leading to cognitive deficits. This study advances current knowledge by showing that even short periods of mechanical ventilation can trigger early neurobehavioral changes. These findings underscore the need for protective ventilation strategies to minimize the systemic effects of mechanical ventilation.
{"title":"Impact of mechanical ventilation on oxidative stress, neuroinflammation, memory and anxiety related behavior: insights from an experimental model.","authors":"Leandro da Silva Cândido, Matheus Ramos Lopes, Pedro Alves Machado-Junior, Aline Maria Dos Santos, Thais Lopes Valetim Di Paschoale Ostolin, Ana Beatriz Farias de Souza, Alexandre Barbosa Reis, Fernanda Cacilda Dos Santos Silva, Deoclécio Alves Chianca-Jr, Frank Silva Bezerra, Rodrigo Cunha Alvim de Menezes","doi":"10.1016/j.resp.2026.104565","DOIUrl":"https://doi.org/10.1016/j.resp.2026.104565","url":null,"abstract":"<p><strong>Background: </strong>Mechanical ventilation is an essential intervention for patients with acute respiratory failure. However, ventilatory strategies with high tidal volumes can be harmful, and are strongly associated with ventilator-induced lung injury. Growing evidence suggests that ventilator-induced lung injury may also trigger oxidative stress and contribute to systemic inflammation and neuronal impairment, particularly in regions such as the hippocampus, which plays a fundamental role in cognitive functions.</p><p><strong>Objective: </strong>Investigate the impact of high tidal volume mechanical ventilation on anxiety-related behaviors, memory, inflammation, and oxidative stress in the central nervous system of male Wistar rats.</p><p><strong>Methods: </strong>Animals were assigned to three groups: spontaneous ventilation, mechanical ventilation with 6mL/kg, and mechanical ventilation with 12mL/kg. Ventilated animals underwent volume-controlled ventilation for 180minutes.</p><p><strong>Results: </strong>Our findings showed that high tidal volume ventilation led to a marked influx of inflammatory cells, increased oxidative stress, and structural damage in the lungs. These pulmonary alterations were accompanied by elevated levels of oxidative markers and pro-inflammatory cytokines in the hippocampus and amygdala. Ventilated animals showed significant deficits in memory-related tasks, and increased anxiety related behaviors.</p><p><strong>Conclusion: </strong>The relationship between oxidative stress, neuroinflammation, and behavioral changes validates the hypothesis that the ventilator-induced lung injury effects extend beyond the lungs, impairing brain function and leading to cognitive deficits. This study advances current knowledge by showing that even short periods of mechanical ventilation can trigger early neurobehavioral changes. These findings underscore the need for protective ventilation strategies to minimize the systemic effects of mechanical ventilation.</p>","PeriodicalId":20961,"journal":{"name":"Respiratory Physiology & Neurobiology","volume":" ","pages":"104565"},"PeriodicalIF":1.6,"publicationDate":"2026-03-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147481502","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Background: Regular training increases Anaerobic Threshold (AT) and improves ventilatory efficiency during exercise. A presence of a Double AT (DT), a delayed ventilatory response to CO2 increase during exercise, was described in some healthy subjects, and may represent a favorable adaptation mechanism for trained subjects. The aim was to investigate the prevalence of DT in trained individuals and the relationship between training and ventilatory efficiency.
Methods: Maximal CardioPulmonary Exercise Test (CPET) of trained subjects were analysed for assessment of AT with the metabolic (V-slope analysis, MetAT) and the ventilatory methods (end-tidal and ventilatory equivalent methods, VentAT). Trained subjects were assigned to groups DT+ or DT- based on the presence/absence of DT, respectively. Trained subjects were also classified by type of sport practiced. Determinants of ventilatory efficiency were assessed at adjusted multivariate regression analysis.
Results: DT was identified in 52 cases out of 205 enrolled (25.4%). No differences by age, sex, body mass index and peak CPET parameters were observed between groups. DT+ subjects had a longer duration and greater ΔVO2 values of isocapnic buffering period. Ventilatory efficiency was negatively associated (better values) with the presence of a DT (p=0.017). Type of sport practiced did not influence the prevalence of DT nor the ventilatory efficiency response.
Conclusion: DT was found in 25.4% of trained people. The presence of DT is not influenced by the type of training and is not related to maximal aerobic capacity; however, subjects with a DT have a greater isocapnic buffering period and a better ventilatory efficiency.
{"title":"ASSESSMENT OF DOUBLE ANAEROBIC THRESHOLD IN TRAINED SUBJECTS.","authors":"Alessio Pellegrino, Mauro Contini, Edoardo Falconi, Alessandro Nava, Lucia Tricarico, Michele Correale, Pietro Amedeo Modesti, Piergiuseppe Agostoni","doi":"10.1016/j.resp.2026.104563","DOIUrl":"https://doi.org/10.1016/j.resp.2026.104563","url":null,"abstract":"<p><strong>Background: </strong>Regular training increases Anaerobic Threshold (AT) and improves ventilatory efficiency during exercise. A presence of a Double AT (DT), a delayed ventilatory response to CO<sub>2</sub> increase during exercise, was described in some healthy subjects, and may represent a favorable adaptation mechanism for trained subjects. The aim was to investigate the prevalence of DT in trained individuals and the relationship between training and ventilatory efficiency.</p><p><strong>Methods: </strong>Maximal CardioPulmonary Exercise Test (CPET) of trained subjects were analysed for assessment of AT with the metabolic (V-slope analysis, MetAT) and the ventilatory methods (end-tidal and ventilatory equivalent methods, VentAT). Trained subjects were assigned to groups DT+ or DT- based on the presence/absence of DT, respectively. Trained subjects were also classified by type of sport practiced. Determinants of ventilatory efficiency were assessed at adjusted multivariate regression analysis.</p><p><strong>Results: </strong>DT was identified in 52 cases out of 205 enrolled (25.4%). No differences by age, sex, body mass index and peak CPET parameters were observed between groups. DT+ subjects had a longer duration and greater ΔVO<sub>2</sub> values of isocapnic buffering period. Ventilatory efficiency was negatively associated (better values) with the presence of a DT (p=0.017). Type of sport practiced did not influence the prevalence of DT nor the ventilatory efficiency response.</p><p><strong>Conclusion: </strong>DT was found in 25.4% of trained people. The presence of DT is not influenced by the type of training and is not related to maximal aerobic capacity; however, subjects with a DT have a greater isocapnic buffering period and a better ventilatory efficiency.</p>","PeriodicalId":20961,"journal":{"name":"Respiratory Physiology & Neurobiology","volume":" ","pages":"104563"},"PeriodicalIF":1.6,"publicationDate":"2026-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147475134","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-21DOI: 10.1016/j.resp.2026.104560
K Michael Spyer, Julian F R Paton
{"title":"Diethelm Richter (1943-2025); a life in Respiratory Neurobiology.","authors":"K Michael Spyer, Julian F R Paton","doi":"10.1016/j.resp.2026.104560","DOIUrl":"https://doi.org/10.1016/j.resp.2026.104560","url":null,"abstract":"","PeriodicalId":20961,"journal":{"name":"Respiratory Physiology & Neurobiology","volume":" ","pages":"104560"},"PeriodicalIF":1.6,"publicationDate":"2026-02-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147277023","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Respiratory dysfunction in people with multiple sclerosis (PwMS) is often attributed to respiratory pump failure, yet central respiratory drive and automatic breathing control remain underexplored. We assessed the prevalence of breathing automatic-voluntary dissociation (AVD) in PwMS.
Methods
We analyzed prospectively collected data from a tertiary care rehabilitation center observational cohort. All adult PwMS, who underwent pulmonary function testing, including a CO₂ ventilatory response test, while relapse-free for ≥ 3 months, between January 2018 and December 2024 were screened. AVD was defined by maximal tidal volume (VTmax) during CO₂ response test higher than vital capacity (VC)(VTmax/VC>1), reflecting discordance between voluntary and automatic respiratory response. Univariate analysis and multivariate logistic regression were performed to identify variables associated with AVD.
Results
Fifty-five PwMS were included (age 59 ±7 years, disease duration 23 ± 11 years, women 64 %, median EDSS 8[7,5;8,5]). Restrictive ventilatory pattern was observed in 65 %, 32 % being severely impaired, and with cough impairment in 64 %. Eighteen (33 %) presented AVD. It was associated with significantly lower VC, inspiratory capacity, peak cough flow (p < 0.001), higher EDSS scores and greater use of respiratory support devices (CPAP/NIV, p = 0.002; mechanical in-exsufflation, p = 0.002).
Conclusion
Breathing AVD is frequent in PwMs with severe disease, underscoring the relevance of thorough respiratory assessment to individualize respiratory care.
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Pub Date : 2026-02-01Epub Date: 2025-12-10DOI: 10.1016/j.resp.2025.104527
T.J. Pereira , H. Edgell
The mechanoreflex mediates the initial cardiorespiratory response during dynamic exercise, via input from the mechanical deformation of the exercising muscle. In response to passive movement (PM), engaging a greater number of limbs elicits a higher heart rate response. Additionally, males have larger pressor responses to arm PM; however, no sex differences exist in the pressor response to leg PM. Considering that the legs are a larger muscle mass and the pressor response to leg PM was not different between sexes, this may suggest inherent limb-dependant differences. This study aimed to determine sex differences and the role of limb volume and muscle strength on the cardiorespiratory responses to arm and leg PM. Females were smaller (i.e., stature, limb volume), less fit and had weaker handgrip strength compared to males (all p < 0.05); although, both sexes had similar plantarflexion strength (p = 0.3). During arm PM, only males experienced an increased MAP response to arm PM (p < 0.001), compared to females (p < 0.05); however, this sex difference was eliminated when accounting for disparities in forearm volume. Males and females had similar cardiorespiratory responses to leg PM (all p > 0.05). Further, greater plantarflexion strength enhanced the ventilatory response to leg PM in both sexes (p = 0.024). Based on covariate analysis, differences in limb volume and muscle strength contributed almost half of the variability in the cardiorespiratory responses to arm or leg PM. Contrary to our hypotheses, the results of the current study suggest that the previously observed sex and limb-dependant differences were influenced by disparities in limb characteristics (i.e., volume or strength).
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