Inspiratory effort is associated with the recruitment of extra-diaphragmatic muscles, including parasternal intercostal muscles (PIMs). The mechanical behavior of PIM and its relationship to indices of inspiratory effort in humans remains poorly characterized. We investigated whether PIM stiffening, assessed using ultrafast ultrasound shear wave elastography (SWE), tracks inspiratory effort breath-by-breath during graded inspiratory loading. Fourteen healthy adults (9 men and 5 women) were studied during quiet breathing and inspiratory threshold loading at 10%, 20%, 30%, and 40% of maximal inspiratory pressure. Inspiratory changes in PIM shear modulus (Δµ) were quantified from SWE and related to esophageal (ΔP̄es) and transdiaphragmatic (ΔP̄di) pressure swings, pressure-time products (PTP̄es and PTP̄di), and crural diaphragm electromyography (EAdi). The ability of Δµ to detect increased inspiratory effort was evaluated per breath using receiver operating characteristic (ROC) analysis. Inspiratory loading induced progressive increases in PIM stiffening (Δµ: 10.2 ± 7.4 to 24.0 ± 15.9 kPa, P < 0.001). Δµ showed strong within-subject correlations with ΔP̄es and ΔP̄di (R = 0.72 and R = 0.68, respectively; both P < 0.0001) and moderate correlations with PTP̄es and PTP̄di (R = 0.50 and R = 0.49, respectively; both P < 0.001). Δµ was also moderately correlated with EAdi (R = 0.45, P < 0.001). Breath-by-breath Δµ discriminated breaths with increased inspiratory effort with a pooled ROC area under the curve of 0.78. PIM stiffening increased proportionally with inspiratory load and was correlated with established pressure- and activation-based indices of inspiratory effort. These findings define the mechanical behavior of the PIM during loaded breathing and identify PIM stiffening as a noninvasive mechanical readout of increased inspiratory effort in humans.NEW & NOTEWORTHY Using ultrasound shear wave elastography, we tracked parasternal intercostal muscle stiffness breath-by-breath during quiet breathing and graded inspiratory threshold loading. Changes in parasternal intercostal muscle stiffness increased progressively with load and were closely associated with indices of inspiratory effort from pressure recordings and diaphragm electrical activity. Stiffness measurements identified breaths with elevated inspiratory effort and may serve as a practical, noninvasive mechanical readout of global inspiratory effort, with potential relevance for respiratory disease assessment and assisted-ventilation monitoring.

INTRODUCTION:Unilateral diaphragmatic dysfunction can cause exertional and postural dyspnoea, along with sleep-related breathing disturbances. Diaphragm plication alleviates daytime symptoms, but its effects on sleep have not been evaluated in detail. METHODS:We analysed prospectively collected observational data in 12 patients undergoing surgical plication for unilateral diaphragmatic dysfunction. Standardised pre- and postoperative assessments included ratings of exertional dyspnoea, orthopnoea and antepnoea (D-VAS), quality of life (VSRQ), spirometry (sitting and supine), transdiaphragmatic twitch pressures, and polysomnography (PSG). Sleep-disordered breathing was evaluated using standard PSG indices including the obstructive apnoea-hypopnoea index (oAHI), measured globally and during REM. RESULTS:Following plication, dyspnoea decreased and orthopnoea and antepnoea were nearly abolished (p = 0.0123 and p = 0.0001, respectively). VSRQ improved (p = 0.0078). Supine vital capacity rose from 52.5% to 75.0% predicted (p = 0.0010), and supine VC drop decreased from 15.1% to 2.65% (p = 0.0068). Twitch pressures increased significantly. oAHI decreased from 15.5 to 8.5 events·h⁻¹ (not significant after multiplicity correction). REM AHI decreased from 43.0 [24.5-66.9] to 19.0 [11.5-23.3] events·h⁻¹ (p = 0.0020), and REM hypopnoea index from 19.5 to 11.0 (p = 0.0098). Strong correlations were found between REM AHI changes and both FRC and expiratory reserve volume (ERV). CONCLUSION:In patients with unilateral diaphragmatic dysfunction, diaphragm plication is associated with improved REM-related obstructive events. This may relate to lung volume restoration. These exploratory findings suggest that prospective studies are needed to determine the usefulness of systematic pre-post plication PSG for patient selection and outcome evaluation.

Abstract In limb muscles, corticospinal excitability is modulated by motor context, with greater facilitation during movement initiation and dynamic contractions than during sustained isometric activation. Whether this applies to the human diaphragm remains uncertain, given the hybrid automatic‐voluntary control and continuous activity of respiratory motoneurones. To determine whether corticospinal excitability of the human diaphragm is influenced by the dynamics of voluntary inspiratory contraction at a given level of inspiratory mouth pressure, nine healthy participants (3 women, 6 men; age 23–39 years) performed inspiratory efforts against an occluded mouthpiece. Diaphragm motor evoked potentials (Di‐MEPs) elicited by transcranial magnetic stimulation were recorded from validated chest surface sites at end‐expiration with the airway occluded, at rest, during sustained static inspiratory efforts at graded fractions of maximal inspiratory mouth pressure (Pi,max), and during dynamic inspiratory efforts matched for pressure (20% Pi,max) but differing in rate of pressure development (slow vs. fast). Static efforts increased Di‐MEP amplitude and shortened latency in a pressure‐dependent manner. Slow dynamic efforts produced similar facilitation to static efforts. Fast dynamic efforts elicited greater facilitation, with increased amplitude and shortened latency. Corticospinal excitability of the diaphragm is modulated by contraction dynamics, with rapid efforts inducing additional facilitation beyond force alone.

N’importe qui peut ralentir, accélérer ou stopper sa respiration. Selon Thomas Similowski, cette capacité a probablement été cruciale pour doter notre espèce de la parole, et nous permet aujourd’hui d’agir, via nos poumons, sur nos propres émotions et ressentis. La capacité a moduler notre respiration a probablement été cruciale pour l’apparition du langage et nous permet aussi d’agir sur nos émotions, selon Thomas Similowski, professeur de pneumologie. Notre capacité à ralentir, accélérer ou stopper notre respiration a probablement été cruciale pour la maîtrise de la parole. Elle nous permet aussi d’agir sur nos émotions. https://www.cerveauetpsycho.fr/sd/psychologie/un-souffle-si-apaisant-14705.php https://www.cerveauetpsycho.fr/sd/memoire/pour-bien-memoriser-respirez-28911.php https://www.cerveauetpsycho.fr/sd/neurosciences/reguler-ses-emotions-en-respirant-20526.php https://www.cerveauetpsycho.fr/sd/neurobiologie/respirer-pour-mieux-penser-18648.php https://www.cerveauetpsycho.fr/sr/ecole-des-cerveauxen-classe-respirez-pour-mieux-penser-17820.php https://www.cerveauetpsycho.fr/sr/ecole-des-cerveauxbien-respirer-pour-mieux-apprendre-25999.php

How does the human brain detect and respond to disruptions in breathing? While animal studies have advanced our understanding of respiratory control, breathing distress in humans remains difficult to treat. It often arises not only from pulmonary lesions or brainstem dysfunction but also from how higher brain regions interpret breathing signals shaped by emotion and experience. We recorded intracranial cortical activity in neurosurgical patients during an interoceptive task involving transient breathing challenges. Conscious detection of these disruptions was predicted by early responses in the anterior insula, which routed signals to orbitofrontal and premotor cortices for appraisal and compensation. These cortical regions preferentially encoded inspiratory effort or airflow, revealing signal-specific processing that echoes functional segregation in brainstem centers. The present findings identify a dynamic insular-frontal circuit for sensing and adapting to respiratory challenges, offering insight into the neural basis of breathing awareness and its disruption in disease.

BACKGROUND:Alternative or adjunctive rehabilitation treatments have emerged for obstructive sleep apnea (OSA) to address low patient compliance with conventional treatments, improve sleep quality, and reduce the number of apnea episodes. OBJECTIVE:To conduct a comprehensive review of respiratory muscle training as a therapeutic adjunct for OSA. Namely, oromyofunctional therapies (OMF), inspiratory muscle training (IMT), and expiratory muscle training (EMT). METHODS:English language articles were selected from the PubMed, Cochrane Library, and ASHA databases, and their methodological quality was assessed using AMSTAR 2. A qualitative review and random-effects meta-analyses were performed on the variables of interest. Because of a specific focus on rehabilitation approaches, we excluded pharmacological therapies and hypoglossal nerve stimulation, thereby centering the research on airway musculature. RESULTS:A total of 247 articles were identified. Four studies were selected for review, comprising a total of 1468 adult patients and 106 pediatric patients. The meta-analyses showed that only OMF, as an adjunctive or stand-alone therapy (mean difference, MD -14.26 events/hour; P < 0.0001; CI 95% -20.98 to -7.54) and EMT (MD -8.42 events/hour; P < 0.0001; CI 95% -12.41 to -4.43) significantly reduced the apnea-hypopnea index (AHI). However, the 3 therapies were all effective in reducing daytime sleepiness (MD -3.50/24 points; P = 0.003; 95% CI -5.78 to -1.22), and IMT, EMT, or a combination of both also improved sleep quality (MD -2.75, P = 0.01; 95% CI -4.85 to -0.66). CONCLUSION:The results of this review suggest that respiratory muscle training improves AHI and has a beneficial effect on clinical symptoms such as sleep quality and daytime sleepiness. Included studies are based on a low level of evidence, despite the generally good methodological quality of the systematic reviews.

Breathing is a fundamental biological rhythm linked to cognition, attention, and social perception. While robots often incorporate anthropomorphic features to enhance engagement, the effect of breathing-like behaviours on the perception of robots and on human-robot interaction (HRI) is largely unexplored. We examined whether simulated robotic breathing influences engagement towards a humanoid robot and its perception. We tested 75 participants (30 men, median age 33) interacting with Softbank Robotics’ Pepper under breathing (simulated respiratory movements, breathing-like sounds) and control (Perlin noise-based movements, purposeless sounds) conditions in a crossover randomised design. Outcome measures included gaze time (primary outcome), duration of human response to robot’s questions, total human-robot interaction duration, ratio of gaze time to interaction duration, Godspeed questionnaire, and in-house questions. Participants spent significantly more time looking at the breathing robot (+ 10.65s [95

Background:Dyspnoea is frequent in mechanically ventilated patients and contributes to substantial distress and a heightened risk of post-traumatic stress disorder. It attests to respiratory-related brain suffering that must be actively managed. This is particularly challenging in noncommunicative patients, hence the interest of electroencephalographic surrogates. This study aims at characterizing the effects of opioids, proposed to relieve dyspnoea, on respiratory-related cortical activity in mechanically ventilated patients. Methods:In a 16-bed intensive care unit (ICU) over a 4-month period, we consecutively included eighteen mechanically ventilated patients with self-reported dyspnoea (visual analog scale -VAS-, communicative patients) or an observation-derived suspicion of respiratory-related brain suffering (noncommunicative patients, respiratory distress observation scores -RDOS-) persisting despite ventilator settings optimisation. Participants underwent electroencephalographic (EEG) recordings before and after administration of intravenous opioids. Respiratory-related cortical activity was assessed using covariance-based connectivity analysis, preinspiratory potentials (PIPs), and time-frequency analysis (TFA) time-locked to inspiration. To disentangle respiratory-specific from general effects of opioids, TFA was also computed from randomly selected EEG segments. Results:Opioids reduced dyspnoea evaluated by VAS and RDOS without significant sedation. EEG covariance analysis showed changes in brain state in 15 of 18 patients. PIP occurrence was variable and not modulated by opioids. TFA revealed statistically significant opioid-induced modulations in low beta and high beta power bands time-locked to inspiration, not observed in randomly timed analyses hence a specific effect of opioids on respiratory-related cortical networks. Conclusion:Opioids can relieve dyspnoea in mechanically ventilated ICU patients and modulate respiratory-related cortical activity beyond their general effects on cortical electrogenesis. This suggests that their effects on breathing control are not limited to brainstem mechanisms.

RATIONALE:Diaphragm dysfunction impedes weaning from mechanical ventilation. Transvenous diaphragm neurostimulation can increase diaphragm strength, but its impact on patient outcomes is uncertain. OBJECTIVES:To test the safety and effectiveness of transvenous diaphragm neurostimulation to increase successful weaning in patients with difficulty weaning from mechanical ventilation in comparison with standard of care. METHODS:This international, multicenter, open-label, randomized clinical trial (RESCUE-3) included adult patients requiring mechanical ventilation for ⩾96 hours who met readiness-to-wean criteria and failed two or more weaning attempts. Patients were randomized to twice-daily transvenous diaphragm neurostimulation (treatment) or standard of care (control). The primary outcome was successful weaning at Day 30. Secondary outcomes included duration of ventilation to Day 30 and mortality at Day 30. The prespecified primary analysis utilized a Bayesian approach with borrowing of prior information from a previous Phase-II randomized trial, downweighted to account for possible differences in trials. MEASUREMENTS AND MAIN RESULTS:Because of slow enrollment and financial considerations, the trial was halted at the first interim analysis after 200 patients were randomized. Overall, 216 patients were randomized in the modified intent-to-treat population (treatment group, n = 102; control group n = 114). At Day 30, 71 (70%) patients in the treatment group and 69 (61%) patients in the control group were successfully weaned (adjusted hazard ratio, 1.34; 95% credible interval = 1.01-1.78; posterior probability of superiority, 97.9%). Treatment reduced the duration of ventilation (adjusted difference, -2.5 d; 95% credible interval = -5.0 to 0.1; posterior probability of superiority, 97.1%). Serious adverse events were reported in 36% of patients in the treatment group and 24% of patients in the control group; 9.8% of patients in the treatment group and 10.5% of patients in the control group died (adjusted hazard ratio, 0.74; 95% credible interval = 0.37-1.46; posterior probability of superiority, 80.6%). CONCLUSIONS:Although the trial was stopped early because of slow enrollment, transvenous diaphragm neurostimulation showed a high probability of potential benefit for weaning success but with a possible increase in serious adverse events.

Objectif Dresser un état des lieux des connaissances, de l’utilisation et du degré de satisfaction des définitions de Détresse Respiratoire Aiguë (DRA) et Insuffisance Respiratoire Aiguë (IRA) dans une population d’étudiants en médecine de 3ème cycle et de médecins de différentes spécialités. Patients et Méthodes Recherche en pédagogie n’impliquant pas la personne humaine se déroulant en deux étapes : état des lieux par une enquête Surveymonkey puis proposition de scénarios "case-based" avec biologie et gaz du sang. Pour chaque cas deux questions étaient posées avec les mêmes propositions afin de permettre de ne pas faire qu’une seule proposition en cas de doute ou de réponses multiples. La durée du questionnaire était de 20 minutes environ. Le questionnaire a été laissé en ligne durant 2 mois. Les critères d’inclusion étaient les cliniciens, pneumologues, réanimateurs, cardiologues, urgentistes ; interne et sénior. Résultats 252 personnes, âgé de 33 (29-40), de sexe masculin dans 57% des cas, ont répondu au questionnaire sur une période de 2 mois de juin 2022 à aout 2022. 37% étaient internes, 30% junior, 23% praticiens hospitaliers et 10% universitaires. 42% étaient de spécialité Médecine Intensive et Réanimation, 26% Pneumologie,16% Anesthésiste Réanimation. A la question « Souhaitez-vous une amélioration des définitions de l’IRA et de la DRA pour améliorer leur utilisation en pratique clinique, 162 participants sur 224 (72 %) répondent « oui ». Conclusion Ce questionnaire encourage à faire évoluer les définitions de DRA et d’IRA dans les enseignements des 2ème et 3ème cycle.

Dyspnea is a major sensory and emotional burden in patients with chronic respiratory insufficiency. While experimentally induced acute dyspnea has been shown to interfere with cognition in healthy participants, interferences between cognition and chronic clinical dyspnea have not been studied. We conducted an exploratory study to examine the association between dyspnea severity and cognitive performance in patients with amyotrophic lateral sclerosis (ALS) and chronic respiratory failure. Twenty patients were studied during unassisted breathing and during non-invasive ventilation (NIV). Dyspnea was assessed using the Multidimensional Dyspnea Profile, and cognitive performance was evaluated using the Paced Auditory Serial Addition Test (PASAT) and the Corsi block-tapping test. Respiratory-related cortical activity was assessed using electroencephalography. Linear mixed-effects models were used to examine associations between dyspnea descriptors and cognitive outcomes, adjusting for age, educational level, and disease severity. NIV markedly relieved dyspnea, anxiety, and respiratory-related cortical activity but was not associated with changes in cognitive performance. Dyspnea unpleasantness was independently associated with longer PASAT response time, whereas no associations were observed with PASAT accuracy measures or Corsi test outcomes. Neither ventilation condition nor respiratory-related cortical activity was associated with cognitive performance. These findings suggest that, in patients with ALS, dyspnea unpleasantness may be associated with slower PASAT response time without detectable relationships with other cognitive measures assessed in this study. Given the exploratory and focal nature of the study, further investigations are warranted to better characterize dyspnea-cognition interactions in this population.

BACKGROUND:Mechanical insufflation-exsufflation (MI-E) improves tracheal secretion clearance in patients with neuromuscular disease. Whether it could mitigate the need for tracheal suctioning without altering comfort and safety in intubated patients free of neuromuscular disease admitted in the ICU is unknown. METHODS:Prospective, randomized, crossover open-label study. Intubated patients without preexisting neuromuscular diseases were included. Two tracheal suctioning strategies were compared: suctioning with prior use of MI-E versus standard suctioning. The primary outcome was the number of tracheal suctioning procedures over a 24-h period. Secondary outcomes included sputum volume collected, blood gas, pain, and adverse events related to suctioning. RESULTS:The study enrolled 40 subjects over a 2-year period. Out of the 201 tracheal suctioning procedures performed during the 24-h MI-E period, 130 (65%) were actually preceded by the use of MI-E. The number of tracheal suctioning procedures was 5 [3-8] during the 24-h MI-E period and 5 [4-8] during the 24-h standard suctioning period (P = .99). There was no difference between MI-E and the standard suctioning 24-h study periods in terms of the volume of secretions suctioned (10 [5-20] mL vs 15 [5-28] mL, P = .81) and behavioral pain scale (4 [3-4] vs 4 [3-5], P = .51). There was no difference in terms of blood gas, arterial desaturation, or any adverse events. No pneumothoraces were observed. CONCLUSION:In subjects intubated in the ICU, the systematic use of MI-E before tracheal suctioning did not reduce the number of suctioning procedures but was not associated with a higher prevalence of adverse events.

Dyspnea is the symptom that conveys the upsetting or distressing awareness of respiratory sensations. It is part of an ensemble of respiratory, neurovegetative, and behavioral manifestations resulting from the brain's reaction to abnormal respiratory-related afferents. This attests to a systemic phenomenon and suggests the existence of measurable biological changes. Different types of experimental respiratory challenges evoke different perceptual, physiological, and psychological responses, suggesting distinct mechanisms and the possibility of varied systemic biological responses. We investigated this hypothesis in 34 healthy volunteers (17 women) exposed to inspiratory threshold loading (ITL) and carbon dioxide stimulation with restricted ventilation (CO2-rv), in a randomized cross-over design. Blood and saliva samples were collected at baseline (T0), at the end of a 5-min dyspnea challenge (T1), and at 30 and 60 min postchallenge (T2 and T3). They were analyzed for neuromodulators and inflammatory biomarkers. Substance P levels rose at all time points during both challenges, but were significantly higher after CO2-rv than after ITL. β-Endorphin levels rose similarly after both challenges, with a correlation to affective dyspnea ratings during ITL only (R = 0.527, P = 0.0023). Brain-derived neurotrophic factor (BDNF) decreased after both stimuli, with lower values following ITL. There were no significant changes in salivary α-amylase, FGF-2, TNF-α, IL-1β, IL-8, or indoleamine/tryptophan 2,3-dioxygenase (IDO/TDO) activity, and salivary cortisol decreased. These results provide a biological substrate for the differences between responses to respiratory challenges. They open new avenues toward biology-guided research into respiratory-related brain suffering.NEW & NOTEWORTHY Dyspnea can be induced through different types of respiratory challenges, including inspiratory loading and carbon dioxide stimulation with restricted ventilation. These paradigms elicit different physiological, perceptual, and psychological responses, suggesting distinct modes of engagement of respiratory-related brain suffering. This study shows that the associated biological responses also differ: Substance P levels were higher during the CO2 challenge, whereas β-endorphin changes were more closely linked to effortful breathing. These results open new avenues toward biology-guided research into respiratory-related brain suffering.

Abstract Contactless assessment of cardiopulmonary function remains an unmet need, with current approaches relying either on subjective clinical examination or on resource-intensive imaging. We evaluated a novel multipoint airborne ultrasound surface motion camera (SMC) designed to map thoracic vibration patterns without contact and to extract clinically relevant information through data-driven analysis. In a prospective observational study, clinically characterised participants underwent short-duration acquisitions during natural breathing and externally induced oscillations. The resulting signals were transformed into spatially and frequency-resolved maps and analysed using machine learning models to discriminate healthy individuals from patients with respiratory or cardiac disease. The approach proved feasible in a clinical setting and achieved excellent discrimination between healthy individuals and respiratory patients (area under the receiver operating characteristic curve (AUC) 0.90 ± 0.07), including in patients with subtle abnormalities not detected by pulmonary function testing. Discrimination between healthy individuals and cardiac patients ranged from acceptable to excellent (AUC 0.76–0.90 depending on subgroup), with the highest performance observed in aortic stenosis. Model interpretability analyses revealed spatial and spectral patterns consistent with the known physiological organisation of lung mechanics and cardiac auscultation areas, supporting a structure–function relationship between recorded signals and underlying processes. These findings indicate that thoracic vibration transmission encodes spatially and spectrally organised information that can be captured without contact and exploited through explainable data-driven modelling. While the results require confirmation in larger populations, this approach may represent an operator-independent, low-burden extension of bedside assessment, with potential applications in early detection, triage, and monitoring of cardiopulmonary disease.

Background and objectives Although sleep disorders of neurological origin have been documented extensively in cases of autoimmune encephalitis, the impact and clinical significance of sleep disordered breathing remain underexplored. We aimed at determining the prevalence of sleep disordered breathing in autoimmune encephalitis. Methods A cohort study of consecutive patients with autoimmune encephalitis referred to a tertiary centre for sleep pathology was conducted over a period of 4.5 years. Patients underwent an overnight videopolysomnography with capnography. We investigated the presence of sleep-related breathing disorders, including sleep-related hypoventilation, sleep apnoea-hypopnoea syndrome, central hyperventilation, irregular breathing and excessive sighing. Results 46 participants with autoimmune encephalitis were included, with a median (interquartile range) age of 60 (40-69) years, of whom three were previously treated with noninvasive ventilation after acute respiratory failure and three were previously treated with positive airway pressure. A total of 26 (56.5%) out of 46 participants had sleep disordered breathing, including 19 (41.3%) out of 46 participants with moderate to severe apnoea-hypopnoea syndrome. Capnography revealed sleep-related hypoventilation in 12 (36%) out of 33 cases, including four (80%) out of five anti-IgLON5, one (25%) out of four antiglutamic acid decarboxylase-65, one (25%) out of four anti-CASPR2, and six (42.8%) out of 14 antibody-negative cases. Nocturnal stridor was observed in two (40%) out of five anti-IgLON5 cases. Overall, 20 (43%) out of 46 subjects required respiratory support, including positive airway pressure (n=13) and noninvasive ventilation (n=7). Conclusion More than one-third of participants with autoimmune encephalitis required nocturnal mechanical ventilation. Particular attention should be paid to sleep-related hypoventilation (assessed by nocturnal capnography) in patients with autoimmune encephalitis to guide timely respiratory support and reduce morbidity and mortality.

Mechanically ventilated patients may experience respiratory suffering, which is difficult to assess when verbal communication is impaired. We evaluated the performance of a steady-state visual evoked potential (SSVEP)-based brain–computer interface (BCI) designed to enable self-reporting of dyspnoea in this context. Forty-nine healthy volunteers were studied under five respiratory conditions: normal breathing (NB), inspiratory resistive loading (IRL), inspiratory threshold loading (ITL), CO₂ inhalation (CO₂), and a return to NB as wash-out (NBWO). Respiratory discomfort was evaluated using a visual analogue scale (VAS). Two BCIs models were tested: a detection BCI (D-BCI), designed to discriminate between ‘breathing is OK’ and ‘breathing is difficult’, and a quantification BCI in the form of a LED-based analogue scale (LAS), composed of five light-emitting diodes. Visual stimuli were delivered at different frequency sets: 12–15 Hz, 15–20 Hz, and 20–30 Hz for the D-BCI; low frequencies (13–17–19–23–29 Hz) and high frequencies (41–43–47–53–59 Hz) for the LAS. Performance was assessed using receiver operating characteristic (ROC) curves; the area under the ROC curve (AUC) was the primary outcome. Participants reported significant respiratory discomfort during IRL, ITL, and CO₂ conditions in the D-BCI groups, and during ITL and CO₂ in the LAS groups, as reflected by higher dyspnoea VAS scores compared to NB. The best-performing frequency sets were 20–30 Hz for the D-BCI (AUC 0.89 [0.89–0.90]) and low frequencies for the LAS (AUC 0.84 [0.83–0.85]). This study demonstrates that an SSVEP-based BCI can sucessfully detect and quantify experimentally induced dyspnoea in healthy individuals. Further research is needed to evaluate its clinical applicability for assessing dyspnoea in non-communicative patients.

ABSTRACT Background Diaphragm dysfunction is an important and often unrecognized cause of dyspnea. The current gold standard, transdiaphragmatic twitch pressure (Pdi,tw), requires oesophageal and gastric balloon catheters and is infrequently used in routine care. We evaluated whether ultrafast ultrasound descriptors of costal diaphragm during bilateral phrenic magnetic stimulation can provide a noninvasive alternative for assessing diaphragm contractility. Methods Thirty patients (19 men and 11 women) referred for suspected diaphragm dysfunction (median age 57 [42–63] years) underwent bilateral anterolateral magnetic stimulation with simultaneous ultrafast ultrasound and oesophageal/gastric pressure recordings. Peak diaphragm tissue velocity, acceleration and jerk were extracted. Associations with Pdi,tw were assessed using ridge regression. Diagnostic performance for detecting abnormal Pdi,tw (< 20 cmH2O) was evaluated using Bayesian receiver operating characteristic (ROC) analysis, including posterior mean AUC and 95% credible intervals. Agreement between predicted and measured Pdi,tw was assessed using Lin's concordance correlation coefficient and Passing–Bablok regression. Results Twenty four of 30 patients (80%) had abnormal Pdi,tw. Ultrafast ultrasound descriptors correlated with Pdi,tw (Spearman's ρ: velocity 0.77 [95% CI, 0.57–0.89], acceleration 0.70 [95% CI, 0.41–0.87], jerk 0.67 [95% CI, 0.43–0.85]; all p < 0.0001). The multivariable ridge model explained 66% of the variance in Pdi,tw and showed high agreement with measured values (Lin's concordance correlation coefficient = 0.87 [95% CI, 0.75–0.93]). Bayesian ROC analysis demonstrated strong discrimination of diaphragm dysfunction (AUC = 0.91; 95% credible interval [CrI], 0.76–0.98). Using the clinical threshold of 20 cmH2O, model‐predicted Pdi,tw yielded a sensitivity of 75% and specificity of 100%. The optimal velocity threshold for discriminating abnormal Pdi,tw was 10.25 mm·ms−1 (95% CrI, 6.12–18.58 mm·ms−1). The corresponding thresholds for acceleration and jerk were 408.6 mm·ms−2 (95% CrI, 122.6–952.4) and 3073 mm·ms−3 (95% CrI, 1038.8–11541.4), respectively. Conclusions Ultrafast ultrasound coupled with magnetic phrenic stimulation provides a feasible, noninvasive, nonvolitional assessment of diaphragm contractility. Diaphragm motion descriptors reliably predicted Pdi,tw and enabled accurate identification of diaphragm dysfunction. These findings support further clinical evaluation and warrant larger multicentre validation studies.

Diagnostic certainty criteria for ICI-myocarditis