Medical hypnosis mitigates laboratory dyspnoea in healthy humans: a randomised, controlled experimental trial.

QUESTION: Dyspnoea persisting despite treatments of underlying causes requires symptomatic approaches. Medical hypnosis could provide relief without the untoward effects of pharmacological approaches. We addressed this question through experimentally induced dyspnoea in healthy humans (inspiratory threshold loading (excessive inspiratory effort) and carbon dioxide stimulation (air hunger)). MATERIAL AND METHODS: 20 volunteers (10 women, aged 21-40 years) were studied on four separate days. The order of the visits was randomised in two steps: firstly, the "inspiratory threshold loading first" versus "carbon dioxide first" group (n=10 in each group); secondly, the "medical hypnosis first" versus "visual distraction first" subgroup (n=5 in each subgroup). Each visit comprised three 5-min periods (reference, intervention, washout) during which participants used visual analogue scales (VAS) to rate the sensory and affective dimensions of dyspnoea, and after which they completed the Multidimensional Dyspnea Profile. RESULTS: Medical hypnosis reduced both dimensions of dyspnoea significantly more than visual distraction (inspiratory threshold loading: sensory reduction after 5 min 34% of full VAS versus 8% (p=0.0042), affective reduction 17.6% versus 2.4% (p=0.044); carbon dioxide: sensory reduction after 5 min 36.9% versus 3% (p=0.0015), affective reduction 29.1% versus 8.7% (p=0.0023)). The Multidimensional Dyspnea Profile showed more marked sensory effects during inspiratory threshold loading and more marked affective effects during carbon dioxide stimulation. ANSWER TO THE QUESTION: Medical hypnosis was more effective than visual distraction at attenuating the sensory and affective dimensions of experimentally induced dyspnoea. This provides a strong rationale for clinical studies of hypnosis in persistent dyspnoea patients.

Sensory interventions to relieve dyspnoea in critically ill mechanically ventilated patients.

BACKGROUND: In critically ill patients receiving mechanical ventilation, dyspnoea is frequent, severe and associated with an increased risk of neuropsychological sequelae. We evaluated the efficacy of sensory interventions targeting the brain rather than the respiratory system to relieve dyspnoea in mechanically ventilated patients. METHODS: Patients receiving mechanical ventilation for ≥48 h and reporting dyspnoea (unidimensional dyspnoea visual analogue scale (Dyspnoea-VAS)) first underwent increased pressure support and then, in random order, auditory stimulation (relaxing music versus pink noise) and air flux stimulation (facial versus lower limb). Treatment responses were assessed using Dyspnoea-VAS, the Multidimensional Dyspnea Profile and measures of the neural drive to breathe (airway occlusion pressure (P 0.1) and electromyography of inspiratory muscles). RESULTS: We included 46 patients (tracheotomy or intubation n=37; noninvasive ventilation n=9). Increasing pressure support decreased Dyspnoea-VAS by median 40 mm (p<0.001). Exposure to music decreased Dyspnoea-VAS compared with exposure to pink noise by median 40 mm (p<0.001). Exposure to facial air flux decreased Dyspnoea-VAS compared with limb air flux by median 30 mm (p<0.001). Increasing pressure support, but not music exposure and facial air flux, reduced P 0.1 by median 3.3 cmH2O (p<0.001). CONCLUSIONS: In mechanically ventilated patients, sensory interventions can modulate the processing of respiratory signals by the brain irrespective of the intensity of the neural drive to breathe. It should therefore be possible to alleviate dyspnoea without resorting to pharmacological interventions or having to infringe the constraints of mechanical ventilation lung protection strategies by increasing ventilatory support.

"In their own words": delineating the contours of dyspnea invisibility in patients with advanced chronic obstructive pulmonary disease from quantitative discourse analysis.

BACKGROUND: Dyspnea conveys an upsetting or distressing experience of breathing awareness. It heavily weighs on chronic respiratory disease patients, particularly when it persists despite maximal treatment of causative abnormalities. The physical, psychological and social impacts of persistent dyspnea are ill-appreciated by others. This invisibility constitutes a social barrier and impedes access to care. This study aimed to better understand dyspnea invisibility in patients with chronic obstructive pulmonary disease (COPD) through quantitative discourse analysis. METHODS: We conducted a lexicometric analysis (lemmatization, descending hierarchical classification, multicomponent analysis, similarity analysis) of 11 patients' discourses (6 men, severe COPD; immediate postexacerbation rehabilitation) to identify semantic classes and communities, which we then confronted with themes previously identified using interpretative phenomenological analysis (IPA). RESULTS: Class#1 ("experience and need for better understanding"; 38.9% of semantic forms, 50% of patients) illustrates the gap that patients perceive between their experience and what others see, confirming the importance of dyspnea invisibility in patients' concerns. Class#2 ("limitations"; 28.7% of forms) and Class#3 (management"; 13.1% of forms) point to the weight of daily limitations in performing basic activities, of the need to accept or adapt to the constraints of the disease. These three classes matched previously identified IPA-derived themes. Class#4 ("hospitalization"; 18.2% of forms) points to the importance of interactions with the hospital, especially during exacerbations, which constitutes novel information. CONCLUSIONS: Lexicometry confirms the importance of dyspnea invisibility as a burden to COPD patients.

Clinical correlates of respiratory disorders in patients with severe multiple sclerosis: A cross-sectional cohort.

BACKGROUND: Respiratory disorders remain incompletely described in multiple sclerosis (MS), even though they are a frequent cause of death. METHODS: The objective was to describe respiratory disorders in MS patients with Expanded Disability Status Score (EDSS) ⩾ 6.5. Diaphragm dysfunction was defined by at least two of the seven criteria: clinical signs, inspiratory recruitment of neck muscles during wakefulness, reduced upright vital capacity (VC) < 80%, upright-to-supine VC ⩾ 15% of upright VC, decrease in Maximal Inspiratory Pressure < 60%, phasic activation of inspiratory neck muscles during sleep, and opposition of thoracic and abdominal movements during sleep. Cough weakness was defined by a peak cough flow < 270 L/min and/or need for cough assist. Sleep apnea syndrome was defined by an apnea-hypopnea index ⩾ 15. RESULTS: Notably, 71 MS patients were included: median age 54 [48, 61] years; median disease duration 21.4 [16.0, 31.4] years. Of these, 52 patients had one or more respiratory disorders; diaphragm dysfunction was the most frequent (n = 34). Patients with diaphragm dysfunction and cough weakness were more disabled. The fatigue score and the cognitive evaluations did not differ between the groups. Five patients required non-invasive ventilation. CONCLUSION: Respiratory disorders are frequent in severe MS, mostly diaphragm dysfunction. Of interest, instrumental interventions are available to address these disorders.

Increasing Sweep Gas Flow Reduces Respiratory Drive and Dyspnea in Nonintubated Venoarterial Extracorporeal Membrane Oxygenation Patients: A Pilot Study.

BACKGROUND: Data on assessment and management of dyspnea in patients on venoarterial extracorporeal membrane oxygenation (ECMO) for cardiogenic shock are lacking. The hypothesis was that increasing sweep gas flow through the venoarterial extracorporeal membrane oxygenator may decrease dyspnea in nonintubated venoarterial ECMO patients exhibiting clinically significant dyspnea, with a parallel reduction in respiratory drive. METHODS: Nonintubated, spontaneously breathing, supine patients on venoarterial ECMO for cardiogenic shock who presented with a dyspnea visual analog scale (VAS) score of greater than or equal to 40/100 mm were included. Sweep gas flow was increased up to +6 l/min by three steps of +2 l/min each. Dyspnea was assessed with the dyspnea-VAS and the Multidimensional Dyspnea Profile. The respiratory drive was assessed by the electromyographic activity of the alae nasi and parasternal muscles. RESULTS: A total of 21 patients were included in the study. Upon inclusion, median dyspnea-VAS was 50 (interquartile range, 45 to 60) mm, and sweep gas flow was 1.0 l/min (0.5 to 2.0). An increase in sweep gas flow significantly decreased dyspnea-VAS (50 [45 to 60] at baseline vs. 20 [10 to 30] at 6 l/min; P < 0.001). The decrease in dyspnea was greater for the sensory component of dyspnea (-50% [-43 to -75]) than for the affective and emotional components (-17% [-0 to -25] and -12% [-0 to -17]; P < 0.001). An increase in sweep gas flow significantly decreased electromyographic activity of the alae nasi and parasternal muscles (-23% [-36 to -10] and -20 [-41 to -0]; P < 0.001). There was a significant correlation between the sweep gas flow and the dyspnea-VAS (r = -0.91; 95% CI, -0.94 to -0.87), between the respiratory drive and the sensory component of dyspnea (r = 0.29; 95% CI, 0.13 to 0.44) between the respiratory drive and the affective component of dyspnea (r = 0.29; 95% CI, 0.02 to 0.54) and between the sweep gas flow and the alae nasi and parasternal (r = -0.31; 95% CI, -0.44 to -0.22; and r = -0.25; 95% CI, -0.44 to -0.16). CONCLUSIONS: In critically ill patients with venoarterial ECMO, an increase in sweep gas flow through the oxygenation membrane decreases dyspnea, possibly mediated by a decrease in respiratory drive.

Dyspnoea relief as an inherent benefit of high flow nasal cannula therapy: A laboratory randomized trial in healthy humans.

BACKGROUND AND OBJECTIVE: Persistent dyspnoea is a public health issue for which the therapeutic arsenal is limited. This study tested high-flow nasal cannula therapy (HFNT) as a means to alleviate experimental dyspnoea. METHODS: Thirty-two healthy subjects underwent an experimental dyspnoea induced by thoracoabdominal elastic loading. HFNT was administered with alternately FiO2 of 100% (HFNT100) or 21% (HFNT21). The sensory (S-VAS) and affective (A-VAS) components of dyspnoea, transcutaneous CO2 pressure (PtcCO2 ), pulse-oximetry oxygen saturation (SpO2 ), heart rate, respiratory rate and skin galvanometry were monitored continuously. Three experimental sessions of 8 min were conducted: the first session consisted in familiarization with the experimental dyspnoea and the next two sessions tested the effects of HFNT100 and HFNT21 alternatively in a randomized order. RESULTS: HFNT21 and HFNT100 significantly reduced dyspnoea, respectively of ∆A-VAS = 0.80 cm [-0.02-1.5]; p = 0.007 and ∆A-VAS = 1.00 cm [0.08-1.75]; p < 0.0001; ∆S-VAS = 0.70 cm [-0.15-1.98]), p < 0.0001 and ∆S-VAS = 0.70 cm [0.08-1.95]), p = 0.0002) with no significant difference between HFNT21 and HFNT100. HFNT did not significantly alter the respiratory rate or the heart rate, reduced PtcCO2 only on room air and GSR under both experimental conditions. CONCLUSION: HFNT was associated with a statistically significant reduction in the intensity of the sensory and affective components of dyspnoea, independent of oxygen addition. This relief of laboratory dyspnoea could result from a reduction of afferent-reafferent mismatch.

Diaphragm Neurostimulation Assisted Ventilation in Critically Ill Patients.

Diaphragm neurostimulation consists of placing electrodes directly on or in proximity to the phrenic nerve(s) to elicit diaphragmatic contractions. Since its initial description in the 18th century, indications have shifted from cardiopulmonary resuscitation to long-term ventilatory support. Recently, the technical development of devices for temporary diaphragm neurostimulation has opened up the possibility of a new era for the management of mechanically ventilated patients. Combining positive pressure ventilation with diaphragm neurostimulation offers a potentially promising new approach to the delivery of mechanical ventilation which may benefit multiple organ systems. Maintaining diaphragm contractions during ventilation may attenuate diaphragm atrophy and accelerate weaning from mechanical ventilation. Preventing atelectasis and preserving lung volume can reduce lung stress and strain and improve homogeneity of ventilation, potentially mitigating ventilator-induced lung injury. Furthermore, restoring the thoracoabdominal pressure gradient generated by diaphragm contractions may attenuate the drop in cardiac output induced by positive pressure ventilation. Experimental evidence suggests diaphragm neurostimulation may prevent neuroinflammation associated with mechanical ventilation. This review describes the historical development and evolving approaches to diaphragm neurostimulation during mechanical ventilation and surveys the potential mechanisms of benefit. The review proposes a research agenda and offers perspectives for the future of diaphragm neurostimulation assisted mechanical ventilation for critically ill patients.

Multimodal physiological correlates of dyspnea ratings during breath-holding in healthy humans.

INTRODUCTION AND OBJECTIVES: Dyspnea is associated with fear and intense suffering and is often assessed using visual analog scales (VAS) or numerical rating scales (NRS). However, the physiological correlates of such ratings are not well known. Using the voluntary breath-holding model of induced dyspnea, we studied healthy volunteers to investigate the temporal relationship between dyspnea, the neural drive to breathe assessed in terms of involuntary thoracoabdominal movements (ITMs) and neurovegetative responses. PARTICIPANTS AND METHODS: Twenty-three participants (10 men; median [interquartile range] age 21 [20-21]) performed three consecutive breath-holds with the continuous assessment of dyspnea (urge-to-breathe) using a 10 cm VAS, thoracic and abdominal circumferences measured with piezoelectric belt-mounted transducers, heart rate and heart rate variability (HRV), and galvanic skin response (GSR). Urge-to-breathe VAS at the onset of ITMs (gasping point) was identified visually or algorithmically. RESULTS: Urge-to-breathe VAS at the end of the breath-hold was 9.7 [8.6-10] cm. Total breath-hold duration was 93 [69-130] s. Urge-to-breathe VAS, ITM, heart rate, HRV, and GSR significantly increased during breath-hold. Urge-to-breathe VAS correlated with the magnitude of the thoracic and abdominal movements (rho = 0.51 and rho = 0.59, respectively, p < 0.001). The urge-to-breathe ratings corresponding with ITM onset were 3.0 [2.0-4.7] cm and 3.0 [1.0-4.0] cm for visual and algorithmic detection, respectively (p = 0.782). CONCLUSION: An urge-to-breathe VAS of 3 cm (30% of full scale on a 10 cm VAS) corresponds to a physiological turning point during the physiological response to voluntary breath-holding in healthy humans.

Respiratory recovery trajectories after severe-to-critical COVID-19: a 1-year prospective multicentre study.

BACKGROUND: Survivors of severe-to-critical coronavirus disease 2019 (COVID-19) may have functional impairment, radiological sequelae and persistent symptoms requiring prolonged follow-up. This pragmatic study aimed to describe their clinical follow-up and determine their respiratory recovery trajectories, and the factors that could influence them and their health-related quality of life. METHODS: Adults hospitalised for severe-to-critical COVID-19 were evaluated at 3 months and up to 12 months post-hospital discharge in this prospective, multicentre, cohort study. RESULTS: Among 485 enrolled participants, 293 (60%) were reassessed at 6 months and 163 (35%) at 12 months; 89 (51%) and 47 (27%) of the 173 participants initially managed with standard oxygen were reassessed at 6 and 12 months, respectively. At 3 months, 34%, 70% and 56% of the participants had a restrictive lung defect, impaired diffusing capacity of the lung for carbon monoxide (D LCO) and significant radiological sequelae, respectively. During extended follow-up, both D LCO and forced vital capacity percentage predicted increased by means of +4 points at 6 months and +6 points at 12 months. Sex, body mass index, chronic respiratory disease, immunosuppression, pneumonia extent or corticosteroid use during acute COVID-19 and prolonged invasive mechanical ventilation (IMV) were associated with D LCO at 3 months, but not its trajectory thereafter. Among 475 (98%) patients with at least one chest computed tomography scan during follow-up, 196 (41%) had significant sequelae on their last images. CONCLUSIONS: Although pulmonary function and radiological abnormalities improved up to 1 year post-acute COVID-19, high percentages of severe-to-critical disease survivors, including a notable proportion of those managed with standard oxygen, had significant lung sequelae and residual symptoms justifying prolonged follow-up.

Lifting dyspnoea invisibility: COVID-19 face masks, the experience of breathing discomfort, and improved lung health perception - a French nationwide survey.

QUESTION ADDRESSED: In contrast with pain, dyspnoea is not visible to the general public, who lack the corresponding experiential baggage. We tested the hypothesis that the generalised use of face masks to fight severe acute respiratory syndrome coronavirus 2 dissemination could change this and sensitise people to respiratory health. METHODS: General population polling (1012-person panel demographically representative of the adult French population, quota sampling method; 517 (51%) female). 860 (85%) answered "no" to "treated for a chronic respiratory disease" ("respiratory healthy"), and 152 answered "yes" ("respiratory disease"). 14% of respiratory healthy respondents reported having a close family member treated for a chronic respiratory disease (RH-family+ ). Respondents described mask-related attitudes, beliefs, inconveniencies, dyspnoea and changes in their respiratory health vision . RESULTS: Compliance with masks was high (94.7%). Dyspnoea ranked first among mask inconveniencies (respiratory disease 79.3%, respiratory healthy 67.3%; p=0.013). "Air hunger" was the main sensory dyspnoea descriptor. Mask-related dyspnoea was independently associated with belonging to RH-family+ (OR 1.85, 95% CI 1.16-2.98) and removing masks to improve breathing (OR 5.21, 95% CI 3.73-7.28). It was negatively associated with considering masks effective to protect others (OR 0.42, 95% CI 0.25-0.75). Half the respondents were more concerned with their respiratory health since wearing masks; 41% reported better understanding patients' experiences. ANSWER TO THE QUESTION: Wearing protective face masks leads to the mass discovery of breathing discomfort. It raises public awareness of what respiratory diseases involve and sensitivity to the importance of breathing. These data should be used as the fulcrum of respiratory health oriented communication actions.

Respiratory distress observation scales to predict weaning outcome.

BACKGROUND: Whether dyspnea is present before starting a spontaneous breathing trial (SBT) and whether it may affect the outcome of the SBT is unknown. Mechanical Ventilation-Respiratory Distress Observation Scale (MV-RDOS) has been proposed as a reliable surrogate of dyspnea in non-communicative intubated patients. In the present study, we sought (1) to describe the evolution of the MV-RDOS during a SBT and (2) to investigate whether MV-RDOS can predict the outcome of the SBT. METHODS: Prospective, single-center study in a twenty-two bed ICU in a tertiary center. Patients intubated since more 48 h who had failed a first SBT were eligible if they meet classical readiness to wean criteria. The MV-RDOS was assessed before, at 2-min, 15-min and 30-min (end) of the SBT. The presence of clinically important dyspnea was inferred by a MV-RDOS value ≥ 2.6. RESULTS: Fifty-eight patients (age 63 [51-70], SAPS II 66 [51-76]; med [IQR]) were included. Thirty-three (57%) patients failed the SBT, whose 18 (55%) failed before 15-min. Twenty-five (43%) patients successfully passed the SBT. A MV-RDOS ≥ 2.6 was present in ten (17%) patients before to start the SBT. All these ten patients subsequently failed the SBT. A MV-RDOS ≥ 2.6 at 2-min predicted a SBT failure with a 51% sensibility and a 88% specificity (AUC 0.741 95% confidence interval [CI] 0.616-0.866, p = 0.002). Best cut-off value at 2-min was 4.3 and predicted SBT failure with a 27% sensibility and a 96% specificity. CONCLUSION: Despite patients met classical readiness to wean criteria, respiratory distress assessed with the MV-RDOS was frequent at the beginning of SBT. Measuring MV-RDOS before to initiate a SBT could avoid undue procedure and reduce patient's exposure to unnecessary mechanical ventilation weaning failure and distress.

'You can't feel what we feel': Multifaceted dyspnoea invisibility in advanced chronic obstructive pulmonary disease examined through interpretative phenomenological analysis.

BACKGROUND: More than a symptom, dyspnoea is an existential experience shaping the lives of those afflicted, particularly when its persistence despite maximal pathophysiological treatments makes it pervasive. It is, however, insufficiently appreciated by concerned people themselves, family members, healthcare professionals and the public (dyspnoea invisibility), limiting access to appropriate care and support. AIM: To provide a better understanding of dyspnoea experiences and its invisibility. DESIGN: Interpretative phenomenological analysis of data collected prospectively through in-depth semi-structured interviews. SETTING/PARTICIPANTS: Pulmonary rehabilitation facility of a tertiary care university hospital; 11 people (six men, five women) with severe chronic obstructive pulmonary disease (stages 3 and 4 of the 4-stage international GOLD classification) admitted for immediate post-exacerbation rehabilitation. RESULTS: We identified several types of dyspnoea invisibility depending on temporality and interlocutors: (1) invisibility as a symptom to oneself; (2) invisibility as a symptom to others; (3) invisibility as an experience that cannot be shared; (4) invisibility as an experience detached from objective measurements; (5) invisibility as an experience that does not generate empathic concern. The notion of invisibility was present in all the identified experiential dimensions of dyspnoea. It was seen as worsening the burden of the disease and as self-aggravating through self-isolation and self-censorship. CONCLUSIONS: The study confirmed that dyspnoea invisibility is a reality for people with advanced chronic obstructive pulmonary disease. It shows dyspnoea invisibility to be a multifaceted burden. Future research should aim at identifying individual and collective measures to overcome dyspnoea invisibility.

Prevalence of hyposmia and hypogeusia in 390 COVID-19 hospitalized patients and outpatients: a cross-sectional study.

Anecdotal evidence rapidly accumulated during March 2020 from sites around the world that sudden hyposmia and hypogeusia are significant symptoms associated with the SARS-CoV-2 pandemic. Our objective was to describe the prevalence of hyposmia and hypogeusia and compare it in hospitalized and non-hospitalized COVID-19 patients to evaluate an association of these symptoms with disease severity. We performed a cross-sectional survey during 5 consecutive days in March 2020, within a tertiary referral center, associated outpatient clinic, and two primary care outpatient facilities in Paris. All SARS-CoV-2-positive patients hospitalized during the study period and able to be interviewed (n = 198), hospital outpatients seen during the previous month (n = 129), and all COVID-19-highly suspect patients in two primary health centers (n = 63) were included. Hospitalized patients were significantly more often male (64 vs 40%) and older (66 vs 43 years old in median) and had significantly more comorbidities than outpatients. Hyposmia and hypogeusia were reported by 33% of patients and occurred significantly less frequently in hospitalized patients (12% and 13%, respectively) than in the health centers' outpatients (33% and 43%, respectively) and in the hospital outpatients (65% and 60%, respectively). Hyposmia and hypogeusia appeared more frequently after other COVID-19 symptoms. Patients with hyposmia and/or hypogeusia were significantly younger and had significantly less respiratory severity criteria than patients without these symptoms. Olfactory and gustatory dysfunction occurs frequently in COVID-19, especially in young, non-severe patients. These symptoms might be a useful tool for initial diagnostic work-up in patients with suspected COVID-19.

Intensity and quality of exertional dyspnoea in patients with stable pulmonary hypertension.

Dynamic hyperinflation is observed during exercise in 60% of patients with clinically stable pulmonary arterial hypertension (PAH) and chronic thromboembolic pulmonary hypertension (CTEPH), intensifying exertional dyspnoea. The impact of dynamic changes in respiratory mechanics during exercise on qualitative dimensions of dyspnoea in these patients has not been evaluated.26 patients (PAH n=17; CTEPH n=9) performed an incremental symptom-limited cycle exercise test. Minute ventilation (V'E), breathing pattern, operating lung volumes and dyspnoea intensity were assessed throughout exercise. Dyspnoea quality was serially assessed during exercise using a three-item questionnaire (dyspnoea descriptors). The inflection point of tidal volume (V T) relative to V'E was determined for each incremental test. Changes in inspiratory capacity during exercise defined two groups of patients: hyperinflators (65%) and non-hyperinflators (35%). Multidimensional characterisation of dyspnoea was performed after exercise using the Multidimensional Dyspnea Profile.In hyperinflators, inspiratory capacity decreased progressively throughout exercise by 0.36 L, while remaining stable in non-hyperinflators. The "work/effort" descriptor was most frequently selected throughout exercise in both types of patients (65% of all responses). At the V T/V'E inflection, work/effort plateaued while "unsatisfied inspiration" descriptors became selected predominantly only in hyperinflators (77% of all responses). In the affective domain, the emotion most frequently associated with dyspnoea was anxiety.In pulmonary hypertension patients who develop hyperinflation during exercise, dyspnoea descriptors referring to unsatisfied inspiration become predominant following the V T/V'E inflection. As these descriptors are generally associated with more negative emotional experiences, delaying or preventing the V T/V'E inflection may have important implications for symptom management in patients with pulmonary hypertension.

Human diaphragm atrophy in amyotrophic lateral sclerosis is not predicted by routine respiratory measures.

Amyotrophic lateral sclerosis (ALS) patients show progressive respiratory muscle weakness leading to death from respiratory failure. However, there are no data on diaphragm histological changes in ALS patients and how they correlate with routine respiratory measurements.We collected 39 diaphragm biopsies concomitantly with laparoscopic insertion of intradiaphragmatic electrodes during a randomised controlled trial evaluating early diaphragm pacing in ALS (https://clinicaltrials.gov; NCT01583088). Myofibre type, size and distribution were evaluated by immunofluorescence microscopy and correlated with spirometry, respiratory muscle strength and phrenic nerve conduction parameters. The relationship between these variables and diaphragm atrophy was assessed using multivariate regression models.All patients exhibited significant slow- and fast-twitch diaphragmatic atrophy. Vital capacity (VC), maximal inspiratory pressure, sniff nasal inspiratory pressure (SNIP) and twitch transdiaphragmatic pressure did not correlate with the severity of diaphragm atrophy. Inspiratory capacity (IC) correlated modestly with slow-twitch myofibre atrophy. Supine fall in VC correlated weakly with fast-twitch myofibre atrophy. Multivariate analysis showed that IC, SNIP and functional residual capacity were independent predictors of slow-twitch diaphragmatic atrophy, but not fast-twitch atrophy.Routine respiratory tests are poor predictors of diaphragm structural changes. Improved detection of diaphragm atrophy is essential for clinical practice and for management of trials specifically targeting diaphragm muscle function.

NIV in amyotrophic lateral sclerosis: The 'when' and 'how' of the matter.

Non-invasive ventilation (NIV) has become an essential part of the treatment of amyotrophic lateral sclerosis (ALS) since 2006. NIV very significantly improves survival, quality of life and cognitive performances. The initial NIV settings are simple, but progression of the disease, ventilator dependence and upper airway involvement sometimes make long-term adjustment of NIV more difficult, with a major impact on survival. Unique data concerning the long-term adjustment of NIV in ALS show that correction of leaks, management of obstructive apnoea and adaptation to the patient's degree of ventilator dependence improve the prognosis. Non-ventilatory factors also impact the efficacy of NIV and various solutions have been described and must be applied, including cough assist techniques, control of excess salivation and renutrition. NIV in ALS has been considerably improved as a result of application of all of these measures, avoiding the need for tracheostomy in the very great majority of cases. More advanced use of NIV also requires pulmonologists to master the associated end-of-life palliative care, as well as the modalities of discontinuing ventilation when it becomes unreasonable.

Effects of inspiratory muscle training on dyspnoea in severe COPD patients during pulmonary rehabilitation: controlled randomised trial.

The benefit of inspiratory muscle training (IMT) combined with a pulmonary rehabilitation programme (PRP) is uncertain. We aimed to demonstrate that, in severe and very severe chronic obstructive pulmonary disease (COPD) patients, IMT performed during a PRP is associated with an improvement of dyspnoea.In a single-blind randomised controlled trial, 150 severe or very severe COPD patients were allocated to follow PRP+IMT versus PRP alone. The evaluations were performed at inclusion and after 4 weeks. The primary outcome was the change in dyspnoea using the Multidimensional Dyspnoea Profile questionnaire at the end of a 6-min walk test (6MWT) at 4 weeks. Secondary outcomes were changes in dyspnoea using the Borg (end of the 6MWT) and modified Medical Research Council scales and in functional parameters (maximal inspiratory pressure (PImax), inspiratory capacity, 6MWT and quality of life). All analyses were performed on an intention-to-treat basis.Dyspnoea decreased significantly in both groups; however, the improvement of dyspnoea was not statistically different between the two groups. We only found a statistically significant greater increase of PImax after IMT+PRP than after PRP alone.In this trial including severe or very severe COPD patients, we did not find a significant benefit of IMT during PRP+IMT as compared to PRP alone on dyspnoea, despite a significantly higher improvement of PImax in the IMT group.

Effects of non-fatiguing respiratory muscle loading induced by expiratory flow limitation during strenuous incremental cycle exercise on metabolic stress and circulating natural killer cells.

Exercise induces release of cytokines and increase of circulating natural killers (NK) lymphocyte during strong activation of respiratory muscles. We hypothesised that non-fatiguing respiratory muscle loading during exercise causes an increase in NK cells and in metabolic stress indices. Heart rate (HR), ventilation (VE), oesophageal pressure (Pes), oxygen consumption (VO2), dyspnoea and leg effort were measured in eight healthy humans (five men and three women, average age of 31 ± 4 years and body weight of 68 ± 10 kg), performing an incremental exercise testing on a cycle ergometer under control condition and expiratory flow limitation (FL) achieved by putting a Starling resistor. Blood samples were obtained at baseline, at peak of exercise and at iso-workload corresponding to that reached at the peak of FL exercise during control exercise. Diaphragmatic fatigue was evaluated by measuring the tension time index of the diaphragm. Respiratory muscle overloading caused an earlier interruption of exercise. Diaphragmatic fatigue did not occur in the two conditions. At peak of flow-limited exercise compared to iso-workload, HR, peak inspiratory and expiratory Pes, NK cells and norepinephrine were significantly higher. The number of NK cells was significantly related to ΔPes (i.e. difference between the most and the less negative Pes) and plasmatic catecholamines. Loading of respiratory muscles is able to cause an increase of NK cells provided that activation of respiratory muscles is intense enough to induce a significant metabolic stress.

Relieving dyspnoea by non-invasive ventilation decreases pain thresholds in amyotrophic lateral sclerosis.

BACKGROUND: Dyspnoea is a threatening sensation of respiratory discomfort that presents many similarities with pain. Experimental dyspnoea in healthy subjects induces analgesia. This 'dyspnoea-pain counter-irritation' could, in reverse, imply that relieving dyspnoea in patients with chronic respiratory diseases would lower their pain thresholds. METHODS: We first determined pressure pain thresholds in 25 healthy volunteers (22-31 years; 13 men; handheld algometer), during unloaded breathing (BASELINE) and during inspiratory threshold loading (ITL). Two levels of loading were used, adjusted to induce dyspnoea self-rated at 60% or 80% of a 10 cm visual analogue scale (ITL6 and ITL8). 18 patients with chronic respiratory failure due to amyotrophic lateral sclerosis (ALS) were then studied during unassisted breathing and after 30 and 60 min of non-invasive ventilation-NIV30 and NIV60-(same dyspnoea evaluation). RESULTS: In healthy volunteers, pressure pain thresholds increased significantly in the deltoid during ITL6 (p<0.05) and ITL8 (p<0.05) and in the trapezius during ITL8 (p<0.05), validating the use of pressure pain thresholds to study dyspnoea-pain counter-irritation. In patients with ALS, the pressure pain thresholds measured in the deltoid during unassisted breathing decreased by a median of 24.5%-33.0% of baseline during NIV30 and NIV60 (p<0.05). CONCLUSION: Relieving dyspnoea by NIV in patients with ALS having respiratory failure is associated with decreased pressure pain thresholds. Clinical implications have yet to be determined, but this observation suggests that patients with ALS could become more susceptible to pain after the institution of NIV, hence the need for reinforced attention towards potentially painful diagnostic and therapeutic interventions.

Real-life assessment of the multidimensional nature of dyspnoea in COPD outpatients.

Dyspnoea is a prominent symptom of chronic obstructive pulmonary disease (COPD). Recent multidimensional dyspnoea questionnaires like the Multidimensional Dyspnea Profile (MDP) individualise the sensory and affective dimensions of dyspnoea. We tested the MDP in COPD outpatients based on the hypothesis that the importance of the affective dimension of dyspnoea would vary according to clinical characteristics.A multicentre, prospective, observational, real-life study was conducted in 276 patients. MDP data were compared across various categories of patients (modified Medical Research Council (mMRC) dyspnoea score, COPD Assessment Test (CAT) score, Global Initiative for Chronic Obstructive Lung Disease (GOLD) airflow obstruction categories, GOLD "ABCD" categories, and Hospital Anxiety and Depression Scale (HADS)). Univariate and multivariate regressions were conducted to explore factors influencing the affective dimension of dyspnoea. Cluster analysis was conducted to create homogeneous patient profiles.The MDP identified a more marked affective dimension of dyspnoea with more severe mMRC, CAT, 12-item Short-Form Health Survey mental component, airflow obstruction and HADS. Multivariate analysis identified airflow obstruction, depressive symptoms and physical activity as determinants of the affective dimension of dyspnoea. Patients clustered into an "elderly, ex-smoker, severe disease, no rehabilitation" group exhibited the most marked affective dimension of dyspnoea.An affective/emotional dimension of dyspnoea can be identified in routine clinical practice. It can contribute to the phenotypic description of patients. Studies are needed to determine whether targeted therapeutic interventions can be designed and whether they are useful.