Respiratory Muscle Strength as a Predictive Biomarker for Survival in Amyotrophic Lateral Sclerosis

[Proposals from a French expert panel for respiratory care in ALS patients]

BACKGROUND

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease characterized by progressive diaphragm weakness and deteriorating lung function. Bulbar involvement and cough weakness contribute to respiratory morbidity and mortality. ALS-related respiratory failure significantly affects quality of life and is the leading cause of death. Non-invasive ventilation (NIV), which is the main recognized treatment for alleviating the symptoms of respiratory failure, prolongs survival and improves quality of life. However, the optimal timing for the initiation of NIV is still a matter of debate. NIV is a complex intervention. Multiple factors influence the efficacy of NIV and patient adherence. The aim of this work was to develop practical evidence-based advices to standardize the respiratory care of ALS patients in French tertiary care centres.

METHODS

For each proposal, a French expert panel systematically searched an indexed bibliography and prepared a written literature review that was then shared and discussed. A combined draft was prepared by the chairman for further discussion. All of the proposals were unanimously approved by the expert panel.

RESULTS

The French expert panel updated the criteria for initiating NIV in ALS patients. The most recent criteria were established in 2005. Practical advice for NIV initiation were included and the value of each tool available for NIV monitoring was reviewed. A strategy to optimize NIV parameters was suggested. Revisions were also suggested for the use of mechanically assisted cough devices in ALS patients.

CONCLUSION

Our French expert panel proposes an evidence-based review to update the respiratory care recommendations for ALS patients in daily practice.

Generation of human iPSC-derived phrenic-like motor neurons to model respiratory motor neuron degeneration in ALS

The fatal motor neuron (MN) disease Amyotrophic Lateral Sclerosis (ALS) is characterized by progressive MN degeneration. Phrenic MNs (phMNs) controlling the activity of the diaphragm are prone to degeneration in ALS, leading to death by respiratory failure. Understanding of the mechanisms of phMN degeneration in ALS is limited, mainly because human experimental models to study phMNs are lacking. Here we describe a method enabling the derivation of phrenic-like MNs from human iPSCs (hiPSC-phMNs) within 30 days. This protocol uses an optimized combination of small molecules followed by cell-sorting based on a cell-surface protein enriched in hiPSC-phMNs, and is highly reproducible using several hiPSC lines. We show further that hiPSC-phMNs harbouring ALS-associated amplification of the C9orf72 gene progressively lose their electrophysiological activity and undergo increased death compared to isogenic controls. These studies establish a previously unavailable protocol to generate human phMNs offering a disease-relevant system to study mechanisms of respiratory MN dysfunction.

Calculated Maximal Volume Ventilation (cMVV) as a Marker of Early Respiratory Failure in Amyotrophic Lateral Sclerosis (ALS)

Respiratory failure assessment is among the most debatable research topics in amyotrophic lateral sclerosis (ALS) clinical research due to the wide heterogeneity of its presentation. Among the different pulmonary function tests (PFTs), maximal voluntary ventilation (MVV) has shown potential utility as a diagnostic and monitoring marker, able to capture early respiratory modification in neuromuscular disorders. In the present study, we explored calculated MVV (cMVV) as a prognostic biomarker in a center-based, retrospective ALS population belonging to the Piemonte and Valle d'Aosta registry for ALS (PARALS). A Spearman's correlation analysis with clinical data and PFTs showed a good correlation of cMVV with forced vital capacity (FVC) and a moderate correlation with some other features such as bulbar involvement, ALSFRS-R total score, blood oxygen (pO2), carbonate (HCO3-), and base excess (BE), measured with arterial blood gas analysis. Both the Cox proportional hazard models for survival and the time to non-invasive ventilation (NIV) measurement highlighted that cMVV at diagnosis (considering cMVV(40) ≥ 80) is able to stratify patients across different risk levels for death/tracheostomy and NIV indication, especially considering patients with FVC% ≥ 80. In conclusion, cMVV is a useful marker of early respiratory failure in ALS, and is easily derivable from standard PFTs, especially in asymptomatic ALS patients with normal FVC measures.

Relation of Motor Impairments to Neuropathologic Changes of Limbic-Predominant Age-Related TDP-43 Encephalopathy in Older Adults

BACKGROUND AND OBJECTIVES

Limbic-predominant age-related transactive response DNA-binding protein 43 (TDP-43) encephalopathy neuropathologic change (LATE-NC) is common and is a major contributor to cognitive decline and Alzheimer dementia in older adults. The objective of the current study was to examine whether LATE-NC was also associated with declining motor function in older adults.

METHODS

Participants were from 2 longitudinal clinical pathologic studies of aging who did not have dementia at the time of enrollment. Postmortem pathologic examination included immunohistochemical staining for TDP-43 in 8 brain regions, which was summarized as a dichotomous variable indicating advanced LATE-NC stages at which TDP-43 pathology had accumulated in the hippocampus, entorhinal, or neocortical regions. Annual motor testing included maximal inspiratory and expiratory pressures (summarized as respiratory muscle strength), grip and pinch strength (summarized as hand strength), finger tapping speed and the Purdue Pegboard Test (summarized as hand dexterity), and walking 8 feet and turning 360° (summarized as gait function). The severity of parkinsonism was also assessed and summarized as a global parkinsonism score. Global cognition was a summary of standardized scores of 19 neuropsychological tests. We used linear mixed-effect models to examine the associations of LATE-NC with longitudinal changes of motor decline and used multivariate random coefficient models to simultaneously examine the associations of LATE-NC with cognitive and motor decline.

RESULTS

Among 1,483 participants (mean age at death 90.1 [SD = 6.4] years, 70% women, mean follow-up 7.4 [SD = 3.8] years), LATE-NC was present in 34.0% (n = 504). In separate linear mixed-effect models controlling for demographics and other brain pathologies, LATE-NC was associated with faster decline in respiratory muscle strength (estimate = -0.857, SE = 0.322, p = 0.008) and hand strength (estimate = -0.005, SE = 0.002, p = 0.005) but was not related to hand dexterity, gait function, or parkinsonism. In multivariate random coefficient models including respiratory muscle strength, hand strength, and global cognition as the outcomes, LATE-NC remained associated with a faster respiratory muscle strength decline rate (estimate = -0.021, SE = 0.009, p = 0.023), but the association with hand strength was no longer significant (estimate = -0.002, SE = 0.003, p = 0.390).

DISCUSSION

Motor impairment, specifically respiratory muscle weakness, may be an unrecognized comorbidity of LATE-NC that highlights the potential association of TDP-43 proteinopathy with noncognitive phenotypes in aging adults.

Neuroprognostication for Patients with Amyotrophic Lateral Sclerosis: An Updated, Evidence-Based Review

Amyotrophic lateral sclerosis (ALS) is a rapidly progressive neurodegenerative disorder that presents and progresses in various ways, making prognostication difficult. Several paradigms exist for providers to elucidate prognosis in a way that addresses not only the amount of time a patient has to live, but also a patient's quality of their life moving forward. Prognostication, with regard to both survivability and quality of life, is impacted by several features that include, but are not limited to, patient demographics, clinical features on presentation, and over time, access to therapy, and access to multidisciplinary clinics. An understanding of the impact that these features have on the life of a patient with ALS can help providers to develop a better and more personalized approach for patients related to their clinical prognosis after a diagnosis is made. The ultimate goal of prognostication is to empower patients with ALS to take control and make decisions with their care teams to ensure that their goals are addressed and met.

Practical Guide to Management of Long-Term Noninvasive Ventilation for Adults With Chronic Neuromuscular Disease

Recent technological advances in respiratory support and monitoring have dramatically enhanced the utility of long-term noninvasive ventilation (NIV). Improved quality of life and prolonged survival have been demonstrated for several common chronic neuromuscular diseases. Many adults with progressive neuromuscular respiratory disease can now comfortably maintain normal ventilation at home to near total respiratory muscle paralysis without needing a tracheostomy. However, current practice in many communities falls short of that potential. Mastery of the new technology calls for detailed awareness of the respiratory cycle; expert knowledge of mechanical devices, facial interfaces, and quantitative monitoring tools for home ventilation; and a willingness to stay current in a rapidly expanding body of clinical research. The depth and breadth of the expertise required to manage home assisted ventilation has given rise to a new focused medical subspecialty in chronic respiratory failure at the interface between pulmonology, critical care, and sleep medicine. For clinicians seeking pragmatic "how to" guidance, this primer presents a comprehensive, physician-directed management approach to long-term NIV of adults with chronic neuromuscular respiratory disease. Bi-level devices, portable ventilators, ventilation modalities, terminology, and monitoring strategies are reviewed in detail. Building on that knowledge base, we present a step-by-step guide to initiation, refinement, and maintenance of home NIV tailored to patient-centered goals of therapy. The quantitative approach recommended incorporates routine monitoring of home ventilation using technologies that have only recently become widely available including cloud-based device telemonitoring and noninvasive measurements of blood gases. Strategies for troubleshooting and problem solving are included.

Predictors of Peak Expiratory Cough Flow in Individuals with Amyotrophic Lateral Sclerosis

Dystussia is prevalent in individuals with amyotrophic lateral sclerosis (ALS), leading to a diminished physiologic capacity to effectively defend the airway. We aimed to identify predictors of peak expiratory cough flow rate in individuals with ALS. One hundred and thirty-four individuals with a confirmed diagnosis of ALS (El-Escorial criteria revised) completed the ALS Functional Rating Scale-Revised (ALSFRS-R) and underwent pulmonary function and cough spirometry testing. Pearson's correlation coefficients and hierarchical multiple regression modeling were conducted to determine predictors of voluntary cough peak expiratory flow rate (p < 0.05). The full model including age, bulbar disease, cough spirometry metrics, and respiratory parameters had a marginal R² = 0.635, F (7, 126) = 30.241, p < 0.0005, adjusted R² = 0.61. Maximum expiratory pressure, compression phase, and vital capacity did not contribute and were therefore removed (p < 0.05). The most parsimonious predictive model included age, bulbar disease, peak inspiratory flow rate and duration, peak expiratory rise time, and inspiratory pressure generation with a marginal R² = 0.543. Although expiratory pressure generation has historically served as the therapeutic target to improve dystussia in ALS, the current dataset highlighted that the inability to quickly and forcefully inspire during the inspiratory phase of voluntary cough places patients at a mechanical disadvantage to generate subsequent high-velocity expiratory airflow to clear the airway. Thus, therapeutic training programs that include both inspiratory and expiratory strength targets may optimize airway clearance capacity in this challenging patient population.

Respiratory muscle training in neuromuscular disease: a systematic review and meta-analysis

Background

Neuromuscular disease causes a progressive decline in ventilatory function which respiratory muscle training may address. Previous systematic reviews have focussed on single diseases, whereas this study systematically reviewed the collective evidence for respiratory muscle training in children and adults with any neuromuscular disease.

Methods

Seven databases were searched for randomised controlled trials. Three reviewers independently reviewed eligibility, extracted characteristics, results, determined risk of bias and combined results using narrative synthesis and meta-analysis.

Results

37 studies (40 publications from 1986–2021, n=951 participants) were included. Respiratory muscle training improved forced vital capacity (standardised mean difference (SMD) 0.40 (95% confidence interval 0.12–0.69)), maximal inspiratory (SMD 0.53 (0.21–0.85)) and maximal expiratory pressure (SMD 0.70 (0.35–1.04)) compared to control (usual care, sham or alternative treatment). No impact on cough, dyspnoea, voice, physical capacity or quality of life was detected. There was high degree of variability between studies.

Discussion

Study heterogeneity (children and adults, different diseases, interventions, dosage and comparators) suggests that the results should be interpreted with caution. Including all neuromuscular diseases increased the evidence pool and tested the intervention overall.

Conclusions

Respiratory muscle training improves lung volumes and respiratory muscle strength in neuromuscular disease, but confidence is tempered by limitations in the underlying research.

A multi-trial, retrospective analysis of the antihypertensive effects of high-resistance, low-volume inspiratory muscle strength training

Above-normal blood pressure (BP) is a primary risk factor for cardiovascular diseases. In a retrospective analysis of five pilot trials, we assessed the BP-lowering effects of high-resistance inspiratory muscle strength training (IMST) in adults aged 18-82 years and the impact of IMST on maximal inspiratory pressure (PIMAX), a gauge of inspiratory muscle strength and independent disease risk factor. Participants were randomized to high-resistance IMST (75% PIMAX) or low-resistance sham (15% PIMAX) training (30 breaths/day, 5-7 days/wk, 6 wk). IMST (n = 67) reduced systolic BP (SBP) by 9 ± 6 mmHg (P < 0.01) and diastolic BP (DBP) by 4 ± 4 mmHg (P < 0.01). IMST-related reductions in SBP and DBP emerged by week 2 of training (-4 ± 8 mmHg and -3 ± 6 mmHg; P ≤ 0.01, respectively) and continued across the 6-wk intervention. SBP and DBP were unchanged with sham training (n = 61, all P > 0.05). Select subject characteristics slightly modified the impact of IMST on BP. Greater reductions in SBP were associated with older age (β = -0.07 ± 0.03; P = 0.04) and greater reductions in DBP associated with medication-naïve BP (β = -3 ± 1; P = 0.02) and higher initial DBP (β = -0.12 ± 0.05; P = 0.04). PIMAX increased with high-resistance IMST and low-resistance sham training, with a greater increase from high-resistance IMST (+20 ± 17 vs. +6 ± 14 cmH2O; P < 0.01). Gains in PIMAX had a modest inverse relation with age (β = -0.20 ± 0.09; P = 0.03) and baseline PIMAX (β = -0.15 ± 0.07; P = 0.04) but not to reductions in SBP or DBP. These compiled findings from multiple independent trials provide the strongest evidence to date that high-resistance IMST evokes clinically significant reductions in SBP and DBP, and increases in PIMAX, in adult men and women.NEW & NOTEWORTHY In young-to-older adult men and women, 6 wk of high-resistance inspiratory muscle strength training lowers casual systolic and diastolic blood pressure by 9 mmHg and 4 mmHg, respectively, with initial reductions observed by week 2 of training. Given blood pressure outcomes with the intervention were only slightly altered by subject baseline characteristics (i.e., age, blood pressure medication, and health status), inspiratory muscle strength training is effective in lowering blood pressure in a broad range of adults.

Proposals from a French expert panel for respiratory care in ALS patients

BACKGROUND

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease characterized by progressive diaphragm weakness and deteriorating lung function. Bulbar involvement and cough weakness contribute to respiratory morbidity and mortality. ALS-related respiratory failure significantly affects quality of life and is the leading cause of death. Non-invasive ventilation (NIV), which is the main recognized treatment for alleviating the symptoms of respiratory failure, prolongs survival and improves quality of life. However, the optimal timing for the initiation of NIV is still a matter of debate. NIV is a complex intervention. Multiple factors influence the efficacy of NIV and patient adherence. The aim of this work was to develop practical evidence-based advices to standardize the respiratory care of ALS patients in French tertiary care centres.

METHODS

For each proposal, a French expert panel systematically searched an indexed bibliography and prepared a written literature review that was then shared and discussed. A combined draft was prepared by the chairman for further discussion. All of the proposals were unanimously approved by the expert panel.

RESULTS

The French expert panel updated the criteria for initiating NIV in ALS patients. The most recent criteria were established in 2005. Practical advice for NIV initiation were included and the value of each tool available for NIV monitoring was reviewed. A strategy to optimize NIV parameters was suggested. Revisions were also suggested for the use of mechanically assisted cough devices in ALS patients.

CONCLUSION

Our French expert panel proposes an evidence-based review to update the respiratory care recommendations for ALS patients in daily practice.

Thoracic Excursion Is a Biomarker for Evaluating Respiratory Function in Amyotrophic Lateral Sclerosis

Objective

To evaluate the usefulness of thoracic excursion as a biomarker in patients with amyotrophic lateral sclerosis (ALS).

Methods

We measured the forced the vital capacity (FVC), thoracic excursion, baseline-to-peak diaphragmatic compound muscle action potential (DCMAP) amplitude, diaphragm thickness at full inspiration (DTfi), Medical Research Council (MRC) sum score for muscle strength, and arterial partial pressures of oxygen and carbon dioxide and administered the Amyotrophic Lateral Sclerosis Functional Rating Scale-Revised (ALSFRS-R) and modified Medical Research Council (mMRC) Dyspnea Scale. The test–retest reliability of thoracic excursion was determined.

Results and Conclusions

Thirty-four patients with ALS and 26 age- and sex-matched healthy participants were enrolled. Thoracic excursion measurement had excellent test–retest reliability (intraclass coefficient: 0.974). Thoracic excursion was more strongly correlated with FVC (r = 0.678, p &lt; 0.001) than DCMAP amplitude (r = 0.501, p = 0.003) and DTfi (r = 0.597, p &lt; 0.001). It was also correlated with ALSFRS-R score (r = 0.610, p &lt; 0.001), MRC sum score (r = 0.470, p = 0.005), and mMRC Dyspnea Scale score (r = −0.446, p = 0.008) and was the most sensitive parameter for assessing dyspnea and FVC. Thoracic excursion decreased as FVC declined in the early and late stages, there were no differences in DCMAP amplitude and DTfi between the early and late stages, and ALSFRS-R score and MRC sum score decreased only in the late stage. Thoracic excursion was well correlated with respiratory function and is useful for predicting respiratory and general dysfunction in patients with ALS regardless of stage.

1,2-Dehydropyrrolizidine Alkaloids: Their Potential as a Dietary Cause of Sporadic Motor Neuron Diseases

Sporadic motor neuron diseases (MNDs), such as amyotrophic lateral sclerosis (ALS), can be caused by spontaneous genetic mutations. However, many sporadic cases of ALS and other debilitating neurodegenerative diseases (NDDs) are believed to be caused by environmental factors, subject to considerable debate and requiring intensive research. A common pathology associated with MND development involves progressive mitochondrial dysfunction and oxidative stress in motor neurons and glial cells of the central nervous system (CNS), leading to apoptosis. Consequent degeneration of skeletal and respiratory muscle cells can lead to death from respiratory failure. A significant number of MND cases present with cancers and liver and lung pathology. This Perspective explores the possibility that MNDs could be caused by intermittent, low-level dietary exposure to 1,2-dehydropyrrolizidine alkaloids (1,2-dehydroPAs) that are increasingly recognized as contaminants of many foods consumed throughout the world. Nontoxic, per se, 1,2-dehydroPAs are metabolized, by particular cytochrome P450 (CYP450) isoforms, to 6,7-dihydropyrrolizines that react with nucleophilic groups (-NH, -SH, -OH) on DNA, proteins, and other vital biochemicals, such as glutathione. Many factors, including aging, gender, smoking, and alcohol consumption, influence CYP450 isoform activity in a range of tissues, including glial cells and neurons of the CNS. Activation of 1,2-dehydroPAs in CNS cells can be expected to cause gene mutations and oxidative stress, potentially leading to the development of MNDs and other NDDs. While relatively high dietary exposure to 1,2-dehydroPAs causes hepatic sinusoidal obstruction syndrome, pulmonary venoocclusive disease, neurotoxicity, and diverse cancers, this Perspective suggests that, at current intermittent, low levels of dietary exposure, neurotoxicity could become the primary pathology that develops over time in susceptible individuals, along with a tendency for some of them to also display liver and lung pathology and diverse cancers co-occurring with some MND/NDD cases. Targeted research is recommended to investigate this proposal.

Acute intermittent hypoxia and respiratory muscle recruitment in people with amyotrophic lateral sclerosis: A preliminary study

Respiratory failure is the main cause of death in amyotrophic lateral sclerosis (ALS). Since no effective treatments to preserve independent breathing are available, there is a critical need for new therapies to preserve or restore breathing ability. Since acute intermittent hypoxia (AIH) elicits spinal respiratory motor plasticity in rodent ALS models, and may restore breathing ability in people with ALS, we performed a proof-of-principle study to investigate this possibility in ALS patients. Quiet breathing, sniff nasal inspiratory pressure (SNIP) and maximal inspiratory pressure (MIP) were tested in 13 persons with ALS and 10 age-matched controls, before and 60 min post-AIH (15, 1 min episodes of 10% O₂, 2 min normoxic intervals) or sham AIH (continuous normoxia). The root mean square (RMS) of the right and left diaphragm, 2nd parasternal, scalene and sternocleidomastoid muscles were monitored. A vector analysis was used to calculate summated vector magnitude (Mag) and similarity index (SI) of collective EMG activity during quiet breathing, SNIP and MIP maneuvers. AIH facilitated tidal volume and minute ventilation (treatment main effects: p < 0.05), and Mag (ie. collective respiratory muscle activity; p < 0.001) during quiet breathing in ALS and control subjects, but there was no effect on SI during quiet breathing. SNIP SI decreased in both groups post-AIH (p < 0.005), whereas Mag was unchanged (p = 0.09). No differences were observed in SNIP or MIP post AIH in either group. Discomfort was not reported during AIH by any subject, nor were adverse events observed. Thus, AIH may be a safe way to increase collective inspiratory muscle activity during quiet breathing in ALS patients, although a single AIH presentation was not sufficient to significantly increase peak inspiratory pressure generation. These preliminary results provide evidence that AIH may improve breathing function in people with ALS, and that future studies of prolonged, repetitive AIH protocols are warranted.

Use of non-invasive ventilation in motor neuron disease - a retrospective cohort analysis

Motor neuron disease (MND) is a neurodegenerative disorder which leads to progressive muscle weakness including respiratory muscle decline. The introduction of non-invasive ventilation (NIV) has been shown to improve quality of life, survival and slow the rate of pulmonary function decline. A retrospective chart analysis of patients who attended the MND clinic from 2014 to 2019 at a tertiary-referral, academic, teaching hospital was carried out to evaluate if NIV and greater compliance with NIV was associated with improved survival. 111 patients were included. The mean age at diagnosis was 63.8 years and 61.3% were males. 66.7% of our cohort used NIV and of this 66.7%, 44.1% were compliant. There was a significantly longer survival in those who used NIV (p = 0.002) and in those who used NIV optimally (p = 0.02) when both groups were compared to those who did not use NIV. In the bulbar MND group those who were compliant with NIV survived longer than who those who did not use NIV (p = 0.001). We found a significantly longer survival with the use of NIV, the use of NIV optimally and with use of NIV in those with bulbar onset MND compared to those who did not use NIV.

Effects of an optimised approach to home-based respiratory care in individuals with amyotrophic lateral sclerosis: a study protocol for a randomised controlled trial

INTRODUCTION

This study aims to investigate the effects of an optimal home-based respiratory care protocol in individuals with amyotrophic lateral sclerosis (ALS).

METHODS AND ANALYSIS

This is a randomised, blinded controlled trial involving patients diagnosed with ALS, both sexes, age between 18 and 80 years. Patients will be randomly allocated into the conventional respiratory care (CRC) group and the optimised respiratory care home-based (ORC) group. Primary outcomes will be peak cough flow, the number of exacerbations and ALS Functional Rating Scale Revised. Secondary outcomes will include chest wall volumes, maximal respiratory pressures, sniff nasal inspiratory pressure, nasal expiratory pressure and forced vital capacity (FVC), forced expiratory volume in the 1st second (FEV1) and FEV1/FVC. The CRC group will receive educational information about respiratory care at the clinic. The ORC group will receive conventional care and home-based care. The clinical status of all individuals will be monitored weekly through telephone calls. A 6-month intervention is planned, the outcomes will be assessed every 3 months and 3 and 6 months follow-up after final evaluation. The primary and secondary results will be described as average or median for continuous variables and absolute and relative frequencies for qualitative variables. Treatment effects or differences between the outcomes (baseline, 3 months and 6 months) of the study groups will be analysed using an analysis of variance. The level of significance will be set as p≤0.05.

ETHICS AND DISSEMINATION

The research ethics committee approved the study. It is expected to evaluate respiratory function in patients with ALS in the short, medium and long terms with home-based care protocol applied. The disease's rapid progression is a limitation for performing a long-term clinical study.

TRIAL REGISTRATION NUMBER

RBR-3z23ts; Pre-results.

The Benefit of Non-invasive Ventilation in Motor Neuron Disease

Background:

Motor Neuron Disease (MND) is a progressive neurodegenerative disorder leading to respiratory muscle weakness with dyspnoea, morning headaches, orthopnoea, poor concentration, unrefreshing sleep, fatigue and daytime somnolence. Respiratory failure is the primary cause of death in those with MND.

Methods:

Although guidelines suggest the use of non-invasive ventilation (NIV) in MND, there lacks clear guidance as to when is the optimal time to initiate NIV and which markers of respiratory muscle decline are the best predictors of prognosis. There have been a number of studies that have found a significant survival advantage to the use of NIV in MND. Similarly, in quality-of-life questionnaires, those treated with NIV tend to perform better and maintain a better quality of life for longer. Furthermore, studies also suggest that improved compliance and greater tolerance of NIV confer a survival advantage.

Results and Discussion:

Forced Vital Capacity (FVC) has traditionally been the main pulmonary function test to determine the respiratory function in those with MND; however, FVC may not be entirely reflective of early respiratory muscle dysfunction. Evidence suggests that sniff nasal inspiratory pressure and maximum mouth inspiratory pressure may be better indicators of early respiratory muscle decline. These measures have been shown to be easier to perform later in the disease, in patients with bulbar onset disease, and may indeed be better prognostic indicators.

Conclusion:

Despite ongoing research, there remains a paucity of randomised controlled data in this area. This review aims to summarise the evidence to date on these topics.

Humoral Influence of Repeated Lineage-Negative Stem/Progenitor Cell Administration on Articulatory Functions in ALS Patients

Amyotrophic lateral sclerosis (ALS) remains a fatal, neurodegenerative disease frequently leading to dysarthria and impaired swallowing. Better understanding of ALS pathophysiology is prompting the use of humoral cell therapies. Hence, a repeated cellular therapy was applied to ALS patients as an attempt to prevent speech deterioration. Autologous bone marrow-derived lineage-negative (Lin⁻) cells were intrathecally administered three times at six-week intervals to 42 sporadic ALS patients. Patients were examined for articulatory functions using subjective (VHI) and objective (FDA) scales. Selected trophic, proinflammatory factors and expression profiles of miRNA were measured in cerebrospinal fluid (CSF) and plasma by multiplex Luminex and q-PCR in different timepoints. Of the 42 patients who received the Lin⁻ cells, 6 showed improvement in articulatory functions, 27 remained stable, and 9 deteriorated after 18 weeks of therapy according to FDA scale. Clinical improvement was particularly evident by the 7^th day of each cell application and concerned better cough and swallow reflex, soft palate, laryngeal time, pitch, and volume. These results correlated with significant changes in the concentration of various trophic and proinflammatory factors and miRNA expression profiles. A multiple application of Lin⁻ cells proved to be safe and feasible. The repeated procedure can potentate a humoral effect and prevent speech deterioration. A short-lasting trophic effect of each Lin⁻ cells administration was observed on local and systemic level. However, further in-depth studies are necessary to sustain the beneficial effect.

Long-Term Mechanical Ventilation: Recommendations of the Swiss Society of Pulmonology

Long-term mechanical ventilation is a well-established treatment for chronic hypercapnic respiratory failure (CHRF). It is aimed at improving CHRF-related symptoms, health-related quality of life, survival, and decreasing hospital admissions. In Switzerland, long-term mechanical ventilation has been increasingly used since the 1980s in hospital and home care settings. Over the years, its application has considerably expanded with accumulating evidence of beneficial effects in a broad range of conditions associated with CHRF. Most frequent indications for long-term mechanical ventilation are chronic obstructive pulmonary disease, obesity hypoventilation syndrome, neuromuscular and chest wall diseases. In the current consensus document, the Special Interest Group of the Swiss Society of Pulmonology reviews the most recent scientific literature on long-term mechanical ventilation and provides recommendations adapted to the particular setting of the Swiss healthcare system with a focus on the practice of non-invasive and invasive home ventilation in adults.

Classifying Patients with Amyotrophic Lateral Sclerosis by Changes in FVC. A Group-based Trajectory Analysis

Rationale: A model for stratifying progression of respiratory muscle weakness in amyotrophic lateral sclerosis (ALS) would identify disease mechanisms and phenotypes suitable for future investigations. This study sought to categorize progression of FVC after presentation to an outpatient ALS clinic.Objectives: To identify clinical phenotypes of ALS respiratory progression based on FVC trajectories over time.Methods: We derived a group-based trajectory model from a single-center cohort of 837 patients with ALS who presented between 2006 and 2015. We applied our model to the Pooled Resource Open-Access ALS Clinical Trials (PRO-ACT) database with 7,461 patients with ALS. Baseline characteristics at first visit were used as predictors of trajectory group membership. The primary outcome was trajectory of FVC over time in months.Measurements and Main Results: We found three trajectories of FVC over time, termed "stable low," "rapid progressor," and "slow progressor." Compared with the slow progressors, the rapid progressors had shorter diagnosis delay, more bulbar-onset disease, and a lower ALS Functional Rating Scale-Revised (ALSFRS-R) total score at baseline. The stable low group had a shorter diagnosis delay, lower body mass index, more bulbar-onset disease, lower ALSFRS-R total score, and were more likely to have an ALSFRS-R orthopnea score lower than 4 compared with the slow progressors. We found that projected group membership predicted respiratory insufficiency in the PRO-ACT cohort (concordance statistic = 0.78, 95% CI, 0.76-0.79).Conclusions: We derived a group-based trajectory model for FVC progression in ALS, which validated against the outcome of respiratory insufficiency in an external cohort. Future studies may focus on patients predicted to be rapid progressors.

NurOwn, phase 2, randomized, clinical trial in patients with ALS: Safety, clinical, and biomarker results

Objective

To determine the safety and efficacy of mesenchymal stem cell (MSC)-neurotrophic factor (NTF) cells (NurOwn®, autologous bone marrow-derived MSCs, induced to secrete NTFs) delivered by combined intrathecal and intramuscular administration to participants with amyotrophic lateral sclerosis (ALS) in a phase 2 randomized controlled trial.

Methods

The study enrolled 48 participants randomized 3:1 (treatment: placebo). After a 3-month pretransplant period, participants received 1 dose of MSC-NTF cells (n = 36) or placebo (n = 12) and were followed for 6 months. CSF was collected before and 2 weeks after transplantation.

Results

The study met its primary safety endpoint. The rate of disease progression (Revised ALS Functional Rating Scale [ALSFRS-R] slope change) in the overall study population was similar in treated and placebo participants. In a prespecified rapid progressor subgroup (n = 21), rate of disease progression was improved at early time points (p < 0.05). To address heterogeneity, a responder analysis showed that a higher proportion of treated participants experienced ≥1.5 points/month ALSFRS-R slope improvement compared to placebo at all time points, and was significant in rapid progressors at 4 and 12 weeks (p = 0.004 and 0.046, respectively). CSF neurotrophic factors increased and CSF inflammatory biomarkers decreased in treated participants (p < 0.05) post-transplantation. CSF monocyte chemoattractant protein-1 levels correlated with ALSFRS-R slope improvement up to 24 weeks (p < 0.05).

Conclusion

A single-dose transplantation of MSC-NTF cells is safe and demonstrated early promising signs of efficacy. This establishes a clear path forward for a multidose randomized clinical trial of intrathecal autologous MSC-NTF cell transplantation in ALS.

Classification of evidence

This phase II study provides Class I evidence.

Dyspnea in amyotrophic lateral sclerosis: The Dyspnea-ALS-Scale (DALS-15) essentially contributes to the diagnosis of respiratory impairment

BACKGROUND

Dyspnea is a cardinal but often underestimated symptom in amyotrophic lateral sclerosis (ALS). The newly developed Dyspnea-ALS-Scale (DALS-15) is highly relevant for therapeutic decisions because dyspnea is a separate criterion to consider noninvasive ventilation (NIV) in ALS. In comparison to the limited effects of neuroprotective compounds, NIV has the greatest impact on survival and improves quality of life.

OBJECTIVE

To investigate whether dyspnea corresponds to parameters of respiratory status mainly used in clinical neurological practice. We also investigated if the DALS-15 could help identify patients for consideration of NIV in whom neither spirometry nor blood gas parameters indicate the need for NIV (forced vital capacity (FVC) < 50% or probable <75%, pCO₂ ≥45  mmHg).

METHODS

Seventy ALS patients with dyspnea according to the DALS-15 obtained blood gas analysis and spirometry (FVC in sitting and supine positions). The supine decline in FVC was calculated.

RESULTS

There was no linear relationship between dyspnea and spirometry as well as blood gases. 83% of our patients had an upright FVC still greater than 50% and no daytime hypercapnia.

CONCLUSIONS

Our study clearly shows that dyspnea can occur independently of objective indicators of respiratory impairment like spirometry or blood gases. Hence, the DALS-15 covers another aspect of respiratory impairment than these tests and refers to the subjective component of respiratory impairment. It detects dyspnea in a considerable proportion of patients in whom NIV should thus be considered although their spirometric and blood gas results do not point towards NIV. The DALS-15 therefore may help to improve the stratification of patients with respiratory impairment for more efficient symptom management and timely coordination of care.

Frontiers in Clinical Practice of Long-Term Care of Chronic Ventilatory Failure

Home mechanical ventilation (HMV) is an effective long-term treatment for chronic hypercapnic respiratory failure. In addition to the established practice of providing HMV for the treatment of chronic ventilatory failure in slowly progressive neuromuscular and chest wall disease, there is accumulating evidence for improvement of quality of life and prolongation of survival by HMV in highly prevalent diseases like chronic obstructive pulmonary disease and ever-increasing obesity hypoventilation syndrome as well as rapidly progressive neuromuscular disease. The key concepts for successful HMV are an experienced team selecting the right patients, timely initiation of adequate ventilation via an appropriate interface, and monitoring effectiveness during regular long-term follow-up. Coaching of patients with chronic respiratory failure on long-term HMV within a dedicated service and collaborations with community services for home care are essential. The current review describes various important practical aspects of HMV that remain frontiers in the implementation of the current knowledge in clinical practice and may help in providing effective HMV to all those in need.

The Dyspnea-ALS-Scale (DALS-15) optimizes individual treatment in patients with amyotrophic lateral sclerosis (ALS) suffering from dyspnea

BACKGROUND

Dyspnea is frequent in amyotrophic lateral sclerosis (ALS) and one of the most bothersome symptoms. The recently developed Dyspnea-ALS-Scale (DALS-15) is a disease-specific patient-reported outcome to detect and quantify dyspnea.

OBJECTIVES

To analyze in a case-based approach the diagnostic and clinical implications and the benefit of the DALS-15 for individual patients in daily clinical routine.

METHODS

Dyspnea was assessed by the 15-item comprising DALS-15 in two patients with ALS. Spirometry was performed and blood gases were analyzed. Results were evaluated in the clinical context of the respective patients.

RESULTS

In one patient the presence of dyspnea detected by the DALS-15 indicated noninvasive ventilation (NIV) although forced vital capacity (FVC) and blood gas analysis were well preserved. After NIV implementation, the DALS-15 was helpful to determine the patient's need for medication, the timing of NIV titration and the adaptation of NIV sessions. In another patient, who was anarthric and no longer able to perform spirometry due to severe bulbar impairment, the DALS-15 allowed a standardized assessment of dyspnea-related distress independently of bulbar dysfunction.

CONCLUSION

The DALS-15 provides a deeper insight into the respiratory status of individual patients. It helps to diagnose respiratory impairment in patients in whom NIV should be considered although FVC and blood gas results do not reveal indication for NIV. It is also valuable for the guidance of patients in later stages of respiratory impairment when NIV is already implemented, and in patients with severe bulbar dysfunction. The DALS-15 can improve specific symptom management and coordination of care and therefore has the potential to optimize individual treatment in ALS patients with dyspnea.

ERS statement on respiratory muscle testing at rest and during exercise

Assessing respiratory mechanics and muscle function is critical for both clinical practice and research purposes. Several methodological developments over the past two decades have enhanced our understanding of respiratory muscle function and responses to interventions across the spectrum of health and disease. They are especially useful in diagnosing, phenotyping and assessing treatment efficacy in patients with respiratory symptoms and neuromuscular diseases. Considerable research has been undertaken over the past 17 years, since the publication of the previous American Thoracic Society (ATS)/European Respiratory Society (ERS) statement on respiratory muscle testing in 2002. Key advances have been made in the field of mechanics of breathing, respiratory muscle neurophysiology (electromyography, electroencephalography and transcranial magnetic stimulation) and on respiratory muscle imaging (ultrasound, optoelectronic plethysmography and structured light plethysmography). Accordingly, this ERS task force reviewed the field of respiratory muscle testing in health and disease, with particular reference to data obtained since the previous ATS/ERS statement. It summarises the most recent scientific and methodological developments regarding respiratory mechanics and respiratory muscle assessment by addressing the validity, precision, reproducibility, prognostic value and responsiveness to interventions of various methods. A particular emphasis is placed on assessment during exercise, which is a useful condition to stress the respiratory system.

Biomarkers in Motor Neuron Disease: A State of the Art Review

Motor neuron disease can be viewed as an umbrella term describing a heterogeneous group of conditions, all of which are relentlessly progressive and ultimately fatal. The average life expectancy is 2 years, but with a broad range of months to decades. Biomarker research deepens disease understanding through exploration of pathophysiological mechanisms which, in turn, highlights targets for novel therapies. It also allows differentiation of the disease population into sub-groups, which serves two general purposes: (a) provides clinicians with information to better guide their patients in terms of disease progression, and (b) guides clinical trial design so that an intervention may be shown to be effective if population variation is controlled for. Biomarkers also have the potential to provide monitoring during clinical trials to ensure target engagement. This review highlights biomarkers that have emerged from the fields of systemic measurements including biochemistry (blood, cerebrospinal fluid, and urine analysis); imaging and electrophysiology, and gives examples of how a combinatorial approach may yield the best results. We emphasize the importance of systematic sample collection and analysis, and the need to correlate biomarker findings with detailed phenotype and genotype data.

Tracking a Fast-Moving Disease: Longitudinal Markers, Monitoring, and Clinical Trial Endpoints in ALS

Amyotrophic lateral sclerosis (ALS) encompasses a heterogeneous group of phenotypes with different progression rates, varying degree of extra-motor involvement and divergent progression patterns. The natural history of ALS is increasingly evaluated by large, multi-time point longitudinal studies, many of which now incorporate presymptomatic and post-mortem assessments. These studies not only have the potential to characterize patterns of anatomical propagation, molecular mechanisms of disease spread, but also to identify pragmatic monitoring markers. Sensitive markers of progressive neurodegenerative change are indispensable for clinical trials and individualized patient care. Biofluid markers, neuroimaging indices, electrophysiological markers, rating scales, questionnaires, and other disease-specific instruments have divergent sensitivity profiles. The discussion of candidate monitoring markers in ALS has a dual academic and clinical relevance, and is particularly timely given the increasing number of pharmacological trials. The objective of this paper is to provide a comprehensive and critical review of longitudinal studies in ALS, focusing on the sensitivity profile of established and emerging monitoring markers.

Amyotrophic Lateral Sclerosis and the Respiratory System

Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disorder that always affects the respiratory muscles. It is characterized by degeneration of motor neurons in the brain and spinal cord. Respiratory complications are the most common causes of death in ALS and typically occur within 3 to 5 years of diagnosis. Because ALS affects both upper and lower motor neurons, it causes hyperreflexia, spasticity, muscle fasciculations, muscle atrophy, and weakness. It ultimately progresses to functional quadriplegia. ALS most commonly begins in the limbs, but in about one-third of cases it begins in the bulbar muscles responsible for speech and swallowing.

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.

Respiratory muscle testing in amyotrophic lateral sclerosis: a practical approach

In amyotrophic lateral sclerosis (ALS), respiratory muscle weakness leads to respiratory failure and death. Non-invasive positive pressure ventilation (NIPPV) appears to reduce lung function decline, thus improving survival and quality-of-life of patients affected by the disease. Unfortunately, clinical features and timing to start NIPPV are not well defined. Starting from recent findings, we examine established and novel tests of respiratory muscle function that could help clinicians decide whether and when to start NIPPV in ALS. Non-invasive tests estimate the function of inspiratory, expiratory, and bulbar muscles, whereas clinical examination allows to assess the overall neurologic and respiratory symptoms and general conditions. Most of the studies recommend that together with a thorough clinical evaluation of the patient according to current guidelines, vital capacity, maximal static and sniff nasal inspiratory pressures, maximal static expiratory pressures and peak cough expiratory flow, and nocturnal pulse oximetry be measured. A sound understanding of physiology can guide the physician also through the current armamentarium for additional supportive treatments for ALS, such as symptomatic drugs and new treatments to manage sialorrhea and thickened saliva, cough assistance, air stacking, and physiotherapy. In conclusion, careful clinical and functional evaluation of respiratory function and patient's preference are key determinants to decide "when" and "to whom" respiratory treatments can be provided.

The Respiratory Phenotype of Rodent Models of Amyotrophic Lateral Sclerosis and Spinocerebellar Ataxia

Amyotrophic lateral sclerosis (ALS) and spinocerebellar ataxia (SCA) are neurodegenerative disorders that result in progressive motor dysfunction and ultimately lead to respiratory failure. Rodent models of neurodegenerative disorders provide a means to study the respiratory motor unit pathology that results in respiratory failure. In addition, they are important for pre-clinical studies of novel therapies that improve breathing, quality of life, and survival. The goal of this review is to compare the respiratory phenotype of two neurodegenerative disorders that have different pathological origins, but similar physiological outcomes. Manuscripts reviewed were identified using specific search terms and exclusion criteria. We excluded manuscripts that investigated novel therapeutics and only included those manuscripts that describe the respiratory pathology. The ALS manuscripts describe pathology in respiratory physiology, the phrenic and hypoglossal motor units, respiratory neural control centers, and accessory respiratory muscles. The SCA rodent model manuscripts characterized pathology in overall respiratory function, phrenic motor units and hypoglossal motor neurons. Overall, a combination of pathology in the respiratory motor units and control centers contribute to devastating respiratory dysfunction.

Mirtazapine for chronic breathlessness? A review of mechanistic insights and therapeutic potential

INTRODUCTION

Chronic breathlessness is a common and distressing symptom of advanced disease with few effective treatments. Central nervous system mechanisms are important in respiratory sensation and control. Consequently, drugs which may modify processing and perception of afferent information in the brain may have a role. Antidepressants have been proposed; however, current evidence is limited. Of potentially suitable antidepressants, mirtazapine is an attractive option given its tolerability profile, low cost, and wide availability, along with additional potential benefits. Areas covered: The paper provides an overview of the physiology of breathlessness, with an emphasis on central mechanisms, particularly the role of fear circuits and the associated neurotransmitters. It provides a potential rationale for how mirtazapine may improve chronic breathlessness and quality of life in patients with advanced disease. The evidence was identified by a literature search performed in PubMed through to October 2018. Expert opinion: Currently, there is insufficient evidence to support the routine use of antidepressants for chronic breathlessness in advanced disease. Mirtazapine is a promising candidate to pursue, with definitive randomized controlled trials required to determine its efficacy and safety in this setting.

Surface mechanomyography and electromyography provide non-invasive indices of inspiratory muscle force and activation in healthy subjects

The current gold standard assessment of human inspiratory muscle function involves using invasive measures of transdiaphragmatic pressure (Pdi) or crural diaphragm electromyography (oesEMGdi). Mechanomyography is a non-invasive measure of muscle vibration associated with muscle contraction. Surface electromyogram and mechanomyogram, recorded transcutaneously using sensors placed over the lower intercostal spaces (sEMGlic and sMMGlic respectively), have been proposed to provide non-invasive indices of inspiratory muscle activation, but have not been directly compared to gold standard Pdi and oesEMGdi measures during voluntary respiratory manoeuvres. To validate the non-invasive techniques, the relationships between Pdi and sMMGlic, and between oesEMGdi and sEMGlic were measured simultaneously in 12 healthy subjects during an incremental inspiratory threshold loading protocol. Myographic signals were analysed using fixed sample entropy (fSampEn), which is less influenced by cardiac artefacts than conventional root mean square. Strong correlations were observed between: mean Pdi and mean fSampEn |sMMGlic| (left, 0.76; right, 0.81), the time-integrals of the Pdi and fSampEn |sMMGlic| (left, 0.78; right, 0.83), and mean fSampEn oesEMGdi and mean fSampEn sEMGlic (left, 0.84; right, 0.83). These findings suggest that sMMGlic and sEMGlic could provide useful non-invasive alternatives to Pdi and oesEMGdi for the assessment of inspiratory muscle function in health and disease.

The Pathophysiology of Respiratory Failure: Control of Breathing, Respiratory Load, and Muscle Capacity

The purpose of this review is to provide an overview on how interactions between control of breathing, respiratory load, and muscle function may lead to respiratory failure. The mechanisms involved vary according to the underlying pathology, but respiratory failure is most often the result of an imbalance between the muscular pump and the mechanical load placed upon it. Changes in respiratory drive and response to CO2 seem to be important contributors to the pathophysiology of respiratory failure. Inspiratory muscle dysfunction is also frequent but is not a mandatory prerequisite to respiratory failure since increased load may also be sufficient to precipitate it. It is crucial to recognize these interactions to be able to timeously establish patients on mechanical ventilation and adapt the ventilator settings to their respiratory system physiology.

Genioglossus muscle activity during sniff and reverse sniff in healthy men

NEW FINDINGS

What is the central question of this study? Maximal sniff nasal inspiratory and reverse sniff nasal expiratory pressures are measured as inspiratory and expiratory muscle strength, respectively. Is the genioglossus muscle activated during short maximal inspiratory and expiratory efforts through the nose? What is the main finding and its importance? Genioglossus muscle activity occurred with inspiratory muscle activity during a maximal sniff and with expiratory muscle activity during a maximal reverse sniff. These results indicate that genioglossus muscle activity is closely related to the generation of maximal sniff nasal inspiratory and reverse sniff nasal expiratory pressures.

ABSTRACT

Maximal sniff nasal inspiratory pressure (SNIP_max ) is widely used to assess inspiratory muscle strength. The sniff nasal inspiratory pressure (SNIP) is lower in patients with neuromuscular disease with bulbar involvement compared with those without, possibly owing to impaired upper airway muscle function. However, the degree to which the genioglossus (GG) muscle, one of the upper airway muscles, is activated during inspiratory and expiratory efforts through the nose remains unclear. Therefore, we examined GG activity during short and sharp inspiratory and expiratory efforts through the nose, i.e. sniff and reverse sniff manoeuvres. In eight normal young subjects, we inserted fine wire electrodes into the GG muscle, parasternal intercostal and scalene (inspiratory) muscles and transversus abdominis (expiratory) muscle. We assessed EMG activity of each muscle and measured SNIP and reverse sniff nasal expiratory pressure (RSNEP) during sniffs and reverse sniffs from low to high intensities in the sitting position. The highest SNIP and RSNEP were analysed as SNIP_max and maximal RSNEP (RSNEP_max ), respectively. In each subject, GG EMG activity increased linearly with increasing SNIP and RSNEP. The SNIP_max and RSNEP_max were -85.1 ± 15.9 and 83.2 ± 24.2 cmH₂ O, respectively. Genioglossus EMG activity varied with EMG activity of the parasternal intercostal and scalene muscles during generation of SNIP_max and with EMG activity of the transversus abdominis muscle during RSNEP_max . Genioglossus EMG activity during generation of SNIP_max was higher than during RSNEP_max (62.9 ± 31.1% EMG of SNIP_max , P = 0.012). These results suggested that GG activity was closely related to the generation of both SNIP_max and RSNEP_max .

Serial changes in exercise capacity, quality of life and cardiopulmonary responses after pulmonary rehabilitation in patients with chronic obstructive pulmonary disease

BACKGROUND AND OBJECTIVES

Patients with chronic obstructive pulmonary disease (COPD) often have poor health-related quality of life (HRQL), exercise capacity and cardiopulmonary function. Pulmonary rehabilitation (PR) is beneficial to improve exercise capacity and HRQL. However, series changes of these parameters remain unclear.

METHODS

Forty-three subjects participated in a 3-months PR program. Subjects were evaluated at baseline and at 8, 16, and 24 sessions after PR.

RESULTS

After 8 sessions, there were significant improvements in the SGRQ-symptom domain, exertional dyspnea, and oxygen pulse (all p < 0.05). Maximal VO₂, SGRQ-activity and SGRQ-impact domains, and respiratory muscle strength were significantly improved after 16 and 24 sessions (all p < 0.05).

CONCLUSIONS

Eight sessions of exercise training lead to improvement of symptoms and exertional dyspnea. 16 to 24 sessions result in further improvement. We suggest patients receive 16 to 24 sessions of PR.

Respiratory Assessment of ALS Patients: A Nationwide Survey of Current Dutch Practice

BACKGROUND AND OBJECTIVE

Non-invasive ventilation (NIV) is an established treatment for respiratory failure in patients with amyotrophic lateral sclerosis (ALS). Several studies have shown room for improvement with regard to respiratory care for ALS patients, including latency of referral. These studies focused on the time period starting at the moment of referral to a home ventilation service (HVS) onwards. In the current study we performed a nationwide survey to gain insight in the trajectory before referral. We questioned the assessment of respiratory impairment by ALS physicians/care teams, including criteria for referral to an HVS.

METHODS

We requested 40 ALS care teams in the Netherlands to fill in an online questionnaire on respiratory management in ALS patients.

RESULTS

Thirty-two ALS care teams (80%) responded. Forced vital capacity was the most frequently used test at each outpatient visit (72%) and often served as a criterion (78%) for referral to an HVS. Other respiratory function measurements that were performed less often included peak cough flow (50%), maximum inspiratory/expiratory pressure (31% /28%) and sniff nasal inspiratory pressure (13%). Morning headache was the most frequently questioned complaint (94%), followed by daytime sleepiness (91%). Dyspnoea and orthopnoea were reported by 38% and 59% as important complaints. Out of all patients under the care of the ALS care teams, the mean estimated proportion of patients that was referred to an HVS was 69% (range 20-100%). When physicians refrained from referral, the most often cited reasons were patient's decision to withhold NIV (94%) and cognitive impairment (50%). Sixteen percent of the respondents stated bulbar impairment as a reason to refrain from referral.

CONCLUSION

Despite findings in previous studies on the superiority of SNIP and PCF as compared to FVC, our study shows that a majority of ALS care teams still prefers to use FVC for the assessment of respiratory dysfunction and for the timing of referral to an HVS. Another finding is that bulbar impairment is not an obstacle for referral for NIV.

Thoracoabdominal asynchrony and paradoxical motion in middle stage amyotrophic lateral sclerosis

AIM

To assess thoracoabdominal asynchrony (TAA) and the presence of paradoxical motion in middle stage amyotrophic lateral sclerosis (ALS) and its relationships with chest wall tidal volume (V_T,CW), breathing pattern and cough peak flow (CPF).

METHODS

Phase angle (θ) between upper (RCp) and lower ribcage (RCa) and abdomen (AB), as well as percentage of inspiratory time for the lower ribcage (IP_RCa) and abdomen (IP_AB) moving in opposite directions were quantified using optoelectronic plethysmography in 12 ALS patients during quiet breathing and coughing. Paradoxical motion of the compartments was based on threshold values of θ and IP, obtained in twelve age and sex matched healthy persons.

RESULTS

During quiet breathing, significantly higher RCa and AB θ (p < .05), IP_RCa (p = 0.001) and IP_AB (p < 0.05) were observed in ALS patients as compared to controls. In ALS patients, correlations between RCa and AB θ with forced vital capacity (FVC) (r=-0.773, p < 0.01), vital capacity (r=-0.663, p < 0.05) and inspiratory capacity (IC) (r=-0.754, p < 0.01), as well as between RCp and RCa θ with FVC (r=-0.608, p < 0.05) and CPF (r=-0.601, p < 0.05) were found. During coughing, correlations between RCp and AB θ with CPF (r=-0.590, p < 0.05), IC (r=-0.748, p < 0.01) and V_T,CW (r=-0.608, p < 0.05), as well as between RCa and AB θ with CPF (r=-0.670, p < 0.05), IC (r=-0.713, p < 0.05) and peak expiratory flow (r=-0.727, p < 0.05) were also observed in ALS patients. ALS patients with paradoxical motion presented lower vital capacity and FVC_%pred (p < 0.05) compared to those without paradoxical motion.

CONCLUSIONS

Middle stage ALS patients exhibit TAA and paradoxical motion during quiet spontaneous breathing and coughing. In addition, diaphragmatic weakness (i.e. decrease in excursion of the RCa and AB compartments) was observed earlier in the lower ribcage rather than the abdominal compartment in this population.

Multiparametric Analysis of Sniff Nasal Inspiratory Pressure Test in Middle Stage Amyotrophic Lateral Sclerosis

The relaxation rates and contractile properties of inspiratory muscles are altered with inspiratory muscle weakness and fatigue. This fact plays an important role in neuromuscular disorders patients and had never been extensively studied in amyotrophic lateral sclerosis (ALS). In this cross-sectional study, these parameters were investigated non-invasively through nasal inspiratory sniff pressure test (SNIP) in 39 middle stage spinal onset ALS subjects and compared with 39 healthy controls. ALS patients were also divided into three subgroups according to a decline in their percentage of predicted forced vital capacity (FVC_%pred) as well as a decline in the ALS functional rating scale score and its respiratory subscore (R-subscore) in order to determine the best parameter linked to early respiratory muscle weakness. When compared with healthy subjects, middle stage ALS subjects exhibited a significantly lower (p < 0.0001) maximum relaxation rate and maximum rate of pressure development (MRPD), as well as a significantly higher (p < 0.0001) tau (τ), contraction time, and half-relaxation time. The results from receiver operating characteristic curves showed that MRPD (AUC 0.735, p < 0.001) and FVC_%pred (AUC 0.749, p = 0.009) were the best discriminator parameters between ALS patients with ≤30 and >30 points in the ALS functional rating scale. In addition, 1/2RT (AUC 0.720, p = 0.01), FVC_%pred (AUC 0.700, p = 0.03), τ (AUC 0.824, p < 0.0001), and MRPD (AUC 0.721, p = 0.01) were the parameters more sensitive in detecting a fall of three points in the R-subscore. On the other hand, MRPD (AUC 0.781, p < 0.001), τ (AUC 0.794, p = 0.0001), and percentage of predicted of SNIP (AUC 0.769, p = 0.002) were the parameters able to detect a fall in 30% of the FVC_%pred in middle stage ALS patients. The contractile properties and relaxation rates of the diaphragm are altered in middle stage spinal onset ALS when compared with healthy subjects. These parameters are able to discriminate between those middle stage ALS subjects with early decline in inspiratory muscle function and those who not.

Breathing: Motor Control of Diaphragm Muscle

Breathing occurs without thought but is controlled by a complex neural network with a final output of phrenic motor neurons activating diaphragm muscle fibers (i.e., motor units). This review considers diaphragm motor unit organization and how they are controlled during breathing as well as during expulsive behaviors.