Spirometry in amyotrophic lateral sclerosis

Onset of age, site and respiratory symptoms are strongly associated with respiratory decline in sporadic amyotrophic lateral sclerosis: a long-term longitudinal study

Objective

The objective of this study is to identify factors influencing progression of respiratory decline from the onset of neurological symptoms to respiratory failure in patients with amyotrophic lateral sclerosis (ALS).

Methods

In 100 patients with sporadic ALS, %vital capacity (%VC) was continuously measured from the first visit to the respiratory endpoint (REP). Cox proportional hazards model identified factors influencing the duration from onset of ALS to REP (Onset-REP). We performed Kaplan-Meier survival curve analysis for onset-REP according to identified factors.

Results

Onset sites were the upper limb (U-ALS), lower limb (L-ALS), bulbar paralysis (B-ALS) and respiratory paralysis (R-ALS) in 37, 19, 32 and 12 patients, respectively. Duration from the onset of ALS to the onset of respiratory symptoms (Onset-Rp) and REP (Onset-REP) was 16.1 (SD 12.1) and 24.9 months (SD 14.6), respectively. Multivariate analysis revealed that age at onset, site of onset, Onset-Rp and %VC decline rate significantly influenced Onset-REP duration. Elderly patients had a significantly shorter Onset-REP duration. Onset-REP duration did not significantly differ between patients with U-ALS and L-ALS, but was longer in these patients than in those with B-ALS and R-ALS. Onset-REP duration was positively associated with Onset-Rp duration. The average monthly %VC decline rate was -5.6% (SD 3.3). Age at onset, onset site and Onset-Rp duration significantly influenced the %VC decline rate.

Conclusions

Our findings revealed strong and independent patient-specific factors that influence the Onset-REP duration and the %VC decline rate in patients with ALS. These could inform future clinical trials and interventions considering the respiratory function and natural history of patients with ALS.

[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.

Pulmonary care for ALS: Progress, gaps, and paths forward

INTRODUCTION

Adults with amyotrophic lateral sclerosis (ALS) have been using home mechanical ventilation for over 50 years. More recently, home respiratory care has evolved to include portable home ventilators, airway clearance devices, and physiological assessments with telemonitoring capability.

CURRENT STATE OF RESPIRATORY CARE

National organizations currently offer incentives for providing a pulmonary care specialist within a multidisciplinary ALS clinic; however, several critical gaps exist between the available technology and employing a clinician with the necessary expertise.

GAPS IN CARE

Lack of formal training and poor financial incentives have led to a paucity of both clinicians and active clinical research engaging in the home respiratory care of ALS. Criteria for noninvasive ventilation (NIV) initiation are controversial, and few guidelines exist on the ideal subsequent adjustments of NIV with evolving disease. Consequently, many patients with ALS tolerate NIV poorly and must face the harrowing decision of hospice vs tracheostomy. Advancement of respiratory care in ALS has been hindered by critical gaps in pulmonologist availability, training in chronic respiratory failure, financial support, clinical research, and clarity on ventilation management beyond initiation.

BRINGING RESPIRATORY CARE UP TO SPEED

Only a multifaceted approach will suffice for addressing the voids in ALS respiratory care, including various education initiatives, financial incentives, clinical research programs, and elevating the standard of respiratory care.

Metabolic Profile and Pathological Alterations in the Muscle of Patients with Early-Stage Amyotrophic Lateral Sclerosis

Diverse biomarkers and pathological alterations have been found in muscle of patients with Amyotrophic lateral sclerosis (ALS), but the relation between such alterations and dysfunction in energetic metabolism remains to be investigated. We established the metabolome of muscle and serum of ALS patients and correlated these findings with the clinical status and pathological alterations observed in the muscle. We obtained data from 20 controls and 17 ALS patients (disease duration: 9.4 ± 6.8 months). Multivariate metabolomics analysis identified a distinct serum metabolome for ALS compared to controls (p-CV-ANOVA < 0.035) and revealed an excellent discriminant profile for muscle metabolome (p-CV-ANOVA < 0.0012). Citramalate was discriminant for both muscle and serum. High lauroylcarnitine levels in muscle were associated with low Forced Vital Capacity. Transcriptomics analysis of key antioxidant enzymes showed an upregulation of SOD3 (p = 0.0017) and GLRX2(1) (p = 0.0022) in ALS muscle. Analysis of mitochondrial enzymatic activity in muscle revealed higher complex II/CS (p = 0.04) and lower LDH (p = 0.03) activity in ALS than in controls. Our study showed, for the first time, a global dysfunction in the muscle of early-stage ALS patients. Furthermore, we identified novel metabolites to be employed as biomarkers for diagnosis and prognosis of ALS patients.

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.

Respiratory function tests in amyotrophic lateral sclerosis: The role of maximal voluntary ventilation

BACKGROUND

Pulmonary function tests are routinely used to measure progression in ALS. This study aimed to assess the change of various respiratory tests, in particular maximal voluntary ventilation (MVV), which evaluates respiratory endurance.

METHODS

A group of 51 patients were assessed 3 times (T1, T2, T3, separated by 5.4 months), including slow (SVC) and forced vital capacity (FVC), forced expiratory volume in 1 s (FEV1), peak expiratory flow (PEF), maximal inspiratory (MIP) and expiratory (MEP) pressures, MVV, and sniff nasal inspiratory pressure (SNIP). In addition, body mass index (BMI), ALSFRS-R and phrenic nerve responses were obtained 4 times. Patients with dementia and marked bulbar involvement were excluded.

RESULTS

Mean ALSFRS-R was high at entry (42.9) and its decline was moderately slow at 0.4/month. FVC and FEV1 declined significantly in the three time frames analysed. MVV reduced significantly only between T1-T3 and SVC between T2-T3, and MIP, MEP, PEF and SNIP did not change significantly. The amplitude and the latency of the motor response of the phrenic nerve changed significantly, and BMI declined significantly in most time periods, and ALSFRS-R changed significantly in the 4 time periods. We found a strong correlation between MVV, and FVC, SVC, FEV1, SNIP, phrenic nerve amplitude/area (p < 0.001), and markedly with PEF (rho = 0.821) and ALSFRS-R (rho = 0.713).

CONCLUSIONS

Our study of early affected patients supports the use of a set of volitional and non-volitional respiratory tests to assess disease progression, rather than any single test. We found MVV a potentially useful marker of pulmonary function in ALS.

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.

Pulmonary function testing in neuromuscular disease

Neuromuscular disorders frequently compromize pulmonary function and effective ventilation, and a thorough respiratory evaluation often can assist in diagnosis, risk assessment, and prognostication. Since many of these disorders can be progressive, serial assessments may be necessary to best define a trajectory of impairment or improvement with therapy. Patients with neuromuscular diseases may have few respiratory symptoms and limited signs of skeletal muscle weakness, but can have significant respiratory muscle weakness. A single testing modality may fail to elucidate true respiratory compromise, and often a combination of tests is recommended to fully evaluate these patients. Common tests performed in this population include measurement of flow rates, lung volumes, maximal pressures, and airways resistance. This review covers the major respiratory testing modalities available in the evaluation of these patients, emphasizing both the benefits and shortcomings of each approach. The majority of parameters are available in a standard pulmonary laboratory (flows, volumes, static pressures), although referral to a specialized center may be necessary to conclusively evaluate a given patient.

Intralingual and Intrapleural AAV Gene Therapy Prolongs Survival in a SOD1 ALS Mouse Model

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease that results in death from respiratory failure. No cure exists for this devastating disease, but therapy that directly targets the respiratory system has the potential to prolong survival and improve quality of life in some cases of ALS. The objective of this study was to enhance breathing and prolong survival by suppressing superoxide dismutase 1 (SOD1) expression in respiratory motor neurons using adeno-associated virus (AAV) expressing an artificial microRNA targeting the SOD1 gene. AAV-miRSOD1 was injected in the tongue and intrapleural space of SOD1G93A mice, and repetitive respiratory and behavioral measurements were performed until the end stage. Robust silencing of SOD1 was observed in the diaphragm and tongue as well as systemically. Silencing of SOD1 prolonged survival by approximately 50 days, and it delayed weight loss and limb weakness in treated animals compared to untreated controls. Histologically, there was preservation of the neuromuscular junctions in the diaphragm as well as the number of axons in the phrenic and hypoglossal nerves. Although SOD1 suppression improved breathing and prolonged survival, it did not ameliorate the restrictive lung phenotype. Suppression of SOD1 expression in motor neurons that underlie respiratory function prolongs survival and enhances breathing until the end stage in SOD1G93A ALS mice.

Diaphragmatic CMAP amplitude from phrenic nerve stimulation predicts functional decline in ALS

OBJECTIVE

To evaluate phrenic nerve motor amplitude (PhrenicAmp) as an independent predictor of functional decline in amyotrophic lateral sclerosis (ALS). We also assessed both PhrenicAmp and forced vital capacity (FVC) as predictors of functional loss in patients with bulbar dysfunction.

METHODS

We included consecutive ALS patients with PhrenicAmp and FVC at baseline. Participants were evaluated with the revised ALS Functional Rating Scale (ALSFRS-R) at inclusion and at, at least, one subsequent follow-up visit. The outcome measure of functional decline was the percentage reduction in ALSFRS-R from baseline. Bulbar dysfunction was defined by the presence of any relevant symptom on the ALSFRS-R bulbar sub-score. Correlations and mixed-effects regressions were used to study the relationship between functional decline and both PhrenicAmp and FVC baseline evaluations.

RESULTS

A total of 249 ALS patients were included; 64.2% of these had bulbar dysfunction. At inclusion, significant correlations were found between PhrenicAmp and FVC (p < 0.001), as well as between each respiratory measure and ALSFRS-R (all p < 0.001). The functional decline at first (median 3 months) and second (median 6 months) follow-up visits was significantly correlated with baseline values of both respiratory evaluations (all p < 0.01) in the entire ALS population, but only with baseline PhrenicAmp (all p < 0.05) in bulbar dysfunction cases. Regression analysis revealed that PhrenicAmp (all p < 0.05), but not FVC, was a significant independent predictor of functional decline in ALS patients and in those with bulbar dysfunction.

CONCLUSION

Baseline PhrenicAmp is an independent predictor of functional decline in ALS, whether or not bulbar dysfunction is present.

Effects of noninvasive ventilation in amyotrophic lateral sclerosis: The complication of bulbar impairment

Amyotrophic lateral sclerosis is a neurodegenerative illness that causes gradual loss of muscle function. Patients eventually develop bulbar impairment, requiring extensive respiratory support. Noninvasive ventilation (NIV) has gained attention as an easily accessible method with promising benefits. We conducted this systematic review to outline the therapeutic effects of NIV, add to previous publications discussing this topic by providing updates on newly completed and ongoing studies, and identify limitations that must be addressed in future trials. A search of PubMed and Cochran for relevant primary studies yielded 26 publications. Studies indicate NIV use is associated with improvements in quality of life, regardless of the severity of bulbar impairment. However, NIV’s benefits on survival were limited to patients with less bulbar impairment. In addition, our review found several limitations that undermine the efforts to establish a definitive treatment regimen. Future studies will need to address these problems in order to provide patients with better respiratory care.

Pattern of lung function decline in patients with amyotrophic lateral sclerosis: implications for timing of noninvasive ventilation

BACKGROUND

The course of lung function decline in amyotrophic lateral sclerosis (ALS) and the effect of noninvasive positive-pressure ventilation (NIPPV) on that decline are uncertain. We sought to model lung function decline, determine when NIPPV is initiated along that course, and assess its impact on the course of decline.

METHODS

An observed sigmoid pattern of forced vital capacity decline was reproduced with a four-parameter nonlinear mixed-effects logistic model.

RESULTS

Analyses were performed on 507 patients overall and in 353 patients for whom a determination of adherence to NIPPV was ascertained. A sigmoid bi-asymptotic model provided a statistical fit of the data and showed a period of stable vital capacity, followed by an accelerated decline, an inflection point, then a slowing in decline to a plateau. By the time NIPPV was initiated in accordance with reimbursement guidelines, vital capacity had declined by ≥85% of the total range. Nearly half of the total loss of vital capacity occurred over 6.2 months centred at an inflection point occurring 17 months after disease onset and 5.2 months before initiation of NIPPV at a vital capacity of about 60%. Fewer bulbar symptoms and a faster rate of decline of lung function predicted adherence to NIPPV, but the intervention had no impact on final vital capacity.

CONCLUSIONS

In patients with ALS, vital capacity decline is rapid but slows after an inflection point regardless of NIPPV. Initiating NIPPV along reimbursement guidelines occurs after ≥85% of vital capacity loss has already occurred.

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.

Pulmonary Function Testing in Neuromuscular and Chest Wall Disorders

Neuromuscular and chest wall disorders frequently compromise pulmonary function, and thorough respiratory evaluation often can assist in diagnosis, risk assessment, and prognosis. Because many of these disorders can be progressive, serial assessments are necessary to best define a trajectory of impairment (or improvement with therapy). This article covers the major respiratory testing modalities available in the evaluation of these patients, emphasizing both the benefits and shortcomings of each approach. Most parameters are available in a standard pulmonary laboratory (flows, volumes, static pressures), although referral to a specialized center may be necessary to conclusively evaluate a given patient.

The pattern of use and survival outcomes of a dedicated adult Home Ventilation and Respiratory Support Service in Singapore: a 7-year retrospective observational cohort study

Background

In Singapore, a dedicated adult multidisciplinary Home Ventilation and Respiratory Support Service (HVRSS) was set-up to assist individuals with chronic ventilatory failure. We aimed to study the use, survival outcomes and identify factors influencing survival in our cohort of ventilator-assisted individuals (VAIs).

Methods

We retrospectively reviewed all referrals to HVRSS from 2009 to 2015. All VAIs were included and divided into 4 categories: (I) amyotrophic lateral sclerosis (ALS); (II) other neuromuscular and chest wall disease (NMCW); (III) spinal cord injury (SCI); and (IV) complex intensive care unit (ICU) groups for comparison of baseline characteristics, co-morbidities, therapy details and survival outcomes. Cox proportional analysis was used to identify important factors influencing survival for ALS and non-ALS VAIs.

Results

There were 112 VAIs; most were male (63%) and ethnic Chinese (83%). At baseline, median [interquartile range (IQR)] age was 61 [46-69] years, body mass index was 20.2 (17.1-23.8) kg/m² and forced vital capacity was 38 [24-65] %predicted. The three most common diseases were ALS (43%), SCI (13%) and congenital muscular dystrophies (6%). Seventy-four (66%) VAIs received non-invasive ventilation (NIV). Median survival for ALS, Complex ICU, SCI and NMCW VAIs were 1.8, 2.6, 4.2 and 6.7 years respectively. In ALS, NIV conversion to invasive mechanical ventilation (IMV) was associated with longer survival [hazard ratio (HR) 0.24]. In non-ALS VAIs, older age (HR 1.40) and cardiovascular comorbidities (HR 2.61) were poor prognostic factors.

Conclusions

The HVRSS managed a heterogenous group of VAIs in Singapore and survival is comparable to published cohorts. ALS had the worst survival whereas NMCW had the best survival with Complex ICU and SCI groups in between. Transition from NIV to IMV, age and cardiovascular disease were important prognostic factors.

SVC Is a Marker of Respiratory Decline Function, Similar to FVC, in Patients With ALS

Introduction: Respiratory function is a critical predictor of survival in amyotrophic lateral sclerosis (ALS). We aimed to determine if slow vital capacity (SVC) is a predictor of functional loss in ALS as compared to forced vital capacity (FVC).

Methods: Consecutive ALS patients in whom respiratory tests were performed at baseline and 6 months later were included. All patients were evaluated with revised ALS functional rating scale (ALSFRS-R) and the respiratory tests, SVC, and FVC. Significant independent variables of functional decay were assessed by univariate Kaplan-Meier log-rank test and multivariate Cox proportional hazards model. A monthly decay not exceeding 0.92 in ALSFRS was considered as the time event.

Results: We included 232 patients (134 men; mean onset-age 59.1 ± 11.23 years; mean disease duration from first symptoms to first visit: 14.5 ± 12.9 months; 166 spinal and 66 bulbar onset). All variables studied declined significantly between the two evaluations (p < 0.001). FVC and SVC were strongly correlated at study entry (r² = 0.98, p < 0.001) and FVC and SVC decays between first evaluation and 6 months after were the only significant prognostic variables of functional decay (p < 0.001).

Conclusion: FVC and SVC decay are inter-changeable in predicting functional decay in ALS. Pharmacological interventions reducing the decline rate of FVC and SVC can have a positive impact on the global functional impairment, with relevant implications for clinical trials' design and interpretation.

Diaphragmatic Neurophysiology and Respiratory Markers in ALS

The main reason for short survival in amyotrophic lateral sclerosis (ALS) is involvement of respiratory muscles. Severe compromise of diaphragmatic function due to marked loss of motor units causes poor inspiratory strength leading to symptomatic respiratory fatigue, and hypercapnia and hypoxemia, often firstly detected while sleeping supine. Weakness of expiratory muscles leads to cough weakness and poor bronchial clearance, increasing the risk of respiratory infection. Respiratory tests should therefore encompass inspiratory and expiratory function, and include measurements of blood gases during sleep. Non-volitional tests, such as phrenic nerve stimulation, are particularly convenient for investigating respiratory function in patients unable to perform standard respiratory function tests due to poor cooperation or facial weakness. However, SNIP is a sensitive test when patients with bulbar involvement are able to perform the necessary maneuvers. It is likely that central respiratory regulation is disturbed in some ALS patients, but its evaluation is more complex and not regularly implemented. Practical tests should incorporate tolerability, sensitivity, easy application for regular monitoring, and prognostic value. Impending respiratory failure can cause increased circulating inflammatory markers, but molecular assessment of respiratory distress requires further study. In future, home-monitoring of patients with accessible devices should be developed.

Mechanisms of compensatory plasticity for respiratory motor neuron death

Respiratory motor neuron death arises from multiple neurodegenerative and traumatic neuromuscular disorders. Despite motor neuron death, compensatory mechanisms minimize its functional impact by harnessing intrinsic mechanisms of compensatory respiratory plasticity. However, the capacity for compensation eventually reaches limits and pathology ensues. Initially, challenges to the system such as increased metabolic demand reveal sub-clinical pathology. With greater motor neuron loss, the eventual result is de-compensation, ventilatory failure, ventilator dependence and then death. In this brief review, we discuss recent advances in our understanding of mechanisms giving rise to compensatory respiratory plasticity in response to respiratory motor neuron death including: 1) increased central respiratory drive, 2) plasticity in synapses on spared phrenic motor neurons, 3) enhanced neuromuscular transmission and 4) shifts in respiratory muscle utilization from more affected to less affected motor pools. Some of these compensatory mechanisms may prolong breathing function, but hasten the demise of surviving motor neurons. Improved understanding of these mechanisms and their impact on survival of spared motor neurons will guide future efforts to develop therapeutic interventions that preserve respiratory function with neuromuscular injury/disease.

Turkish Thoracic Society Consensus Report: Interpretation of Spirometry

ÖZET: Günümüzde spirometre ölçümlerinin uygulama ve yorumlama nitelik güvencesi "American Thoracic Society / European Respiratory Society" standartları ile belirlenmiştir. Dünyada olduğu gibi ülkemizde de birçok laboratuvar bu standartları kullanmaktadır. Buna karşın, farklı laboratuvarlardan farklı değerlendirme sonuçları görebilmek mümkündür. Bu rapor, ülkemizdeki solunum fonksiyon testi laboratuvarlarında yapılan değerlendirmelerin standardizasyonunu sağlamak amacı ile hazırlanmıştır.

Respiratory measures in amyotrophic lateral sclerosis

OBJECTIVE

Amyotrophic lateral sclerosis (ALS) is a progressive neuromuscular disease that causes skeletal muscle weakness, including muscles involved with respiration. Death often results from respiratory failure within 3-5 years. Monitoring respiratory status is therefore critical to ALS management, as respiratory/pulmonary function tests (PFTs) are used to make decisions including when to initiate noninvasive ventilation. Understanding the different respiratory and PFTs as they relate to disease progression and survival may help determine which tests are most suitable.

METHODS

This review describes the tests used to assess respiratory muscle and pulmonary function in patients with ALS and the correlations between different respiratory measures and clinical outcomes measures.

RESULTS

The most commonly used measurement, forced vital capacity (VC), has been shown to correlate with clinical milestones including survival, but also requires good motor coordination and facial strength to form a tight seal around a mouthpiece. Other tests such as slow VC, sniff inspiratory pressure, or transdiaphragmatic pressure with magnetic stimulation are also associated with distinct advantages and disadvantages.

CONCLUSIONS

Therefore, how and when to use different tests remains unclear. Understanding how each test relates to disease progression and survival may help determine which is best suited for specific clinical decisions.

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.

Home Mechanical Ventilation: An Overview

Prevalence studies have shown heterogeneous use of home mechanical ventilation in different conditions, with a marked increase in uptake especially in users of noninvasive ventilation. Although randomized controlled trials have examined noninvasive ventilation in acute exacerbations of chronic obstructive pulmonary disease, for weaning from invasive ventilation and for postextubation respiratory failure, the evidence base for long-term noninvasive ventilation and comparisons with invasive ventilation are less well developed. The combination of noninvasive ventilation and cough-assist devices has reduced the indications for tracheotomy ventilation in some situations (e.g., Duchenne muscular dystrophy, spinal muscular atrophy, myopathies, and amyotrophic lateral sclerosis) and has also prolonged survival. Several excellent overviews have been written on the history of home mechanical ventilation and its evolution from negative pressure to positive pressure techniques, including a systematic review of outcomes. This review, instead, will cover recent trials, trends in the field, outcomes, and safety. Because the greatest growth has been in home noninvasive ventilation, this will be the main focus of this article.

Comparison of slow and forced vital capacities on ability to predict survival in ALS

INTRODUCTION

Slow (SVC) and forced (FVC) vital capacities are the most used pulmonary function tests in amyotrophic lateral sclerosis (ALS). It is unknown if they equally predict survival in ALS. The aim of the present study was to compare both measures in predicting survival in this disease.

METHODS

Consecutive definite/probable ALS patients (2000-2014) in whom respiratory tests were performed at baseline and four months later were included. All patients were evaluated with the revised ALS functional rating scale (ALSFRS-R), respiratory (RofALSFRS-R), bulbar (ALSFRSb), upper and lower limb subscores, SVC, FVC, maximal inspiratory (MIP) and expiratory (MEP) pressures. King's functional staging system was applied retrospectively. Survival analysis was carried out by univariate Kaplan-Meier log-rank test. Multivariate Cox proportional hazards model determined significant independent variables.

RESULTS

We included 469 patients (270 males; mean onset age 61.0 ± 11.5 years; mean disease duration from first symptoms to first visit: 15.8 ± 16.1months; 329 spinal and 140 bulbar onset). FVC and SVC were strongly correlated (r² = 0.981, p < 0.001). Significant survival prognostic variables (Kaplan-Meier analyses) were onset region, age, disease duration, ALSFRS-R, ALSFRSb, RofALSFRS-R, ALSFRS-R decay, SVC, FVC, MIP, MEP and King's staging (p ≤ 0.01). Final Cox model including the significant variables showed similar results for FVC and SVC (p < 0.001). Moreover, 1% decrease in either predicted values increased death probability by 1.02.

CONCLUSION

FVC and SVC are inter-changeable in predicting survival in ALS.

The "Complex Restrictive" Pulmonary Function Pattern: Clinical and Radiologic Analysis of a Common but Previously Undescribed Restrictive Pattern

BACKGROUND

Most patients with restriction have a pulmonary function test (PFT) pattern in which total lung capacity (TLC), FVC, and FEV₁ are reduced to a similar degree. This pattern is called "simple restriction" (SR). In contrast, we commonly observe a pattern in which FVC percent predicted (_pp) is disproportionately reduced relative to TLC_pp. This pattern is termed "complex restriction" (CR), and we attempted to characterize its clinical, radiologic, and physiologic features.

METHODS

This study reviewed PFT results of patients tested between November 2009 and June 2013 who had restriction (TLC less than the lower limit of normal). SR was defined as TLC_pp-FVC_pp ≤ 10%, and CR was stratified into four classes based on TLC_pp-FVC_pp discrepancy: Class 1 CR, TLC_pp-FVC_pp > 10% and ≤ 15%; Class 2 CR, TLC_pp-FVC_pp > 15% and ≤20%; Class 3 CR, TLC_pp-FVC_pp > 20% and ≤ 25%; and Class 4 CR, TLC_pp-FVC_pp > 25%. The medical records of 150 randomly selected patients with SR and 50 patients from each CR class were reviewed.

RESULTS

Of 39,277 PFTs completed, we identified 4,532 patients (11.5%) with restriction: 2,407 (6.1%) with SR, 1,614 (4.1%) with CR, and 511 (1.3%) with a mixed pattern. Patients with CR were younger, were more often women, and had a higher prevalence of neuromuscular disease, BMI > 40 kg/m² or < 18.5 kg/m², diaphragmatic dysfunction, bronchiectasis, CT mosaic attenuation, and pulmonary hypertension (P < .0001, < .0001, < .001, .004, .0008, .002, .008, .009, .053, and .01, respectively) and a lower prevalence of interstitial lung disease (P < .0001).

CONCLUSIONS

CR is a common PFT pattern with distinct clinical features. The associated clinical entities share impaired lung emptying (eg, neuromuscular disease, occult obstruction, chest wall limitation). Clinicians should be aware of this novel PFT pattern and how it shapes the differential diagnosis.

Severe respiratory changes at end stage in a FUS-induced disease state in adult rats

Background

Fused in sarcoma (FUS) is an RNA-binding protein associated with the neurodegenerative diseases amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration. ALS manifests in patients as a progressive paralysis which leads to respiratory dysfunction and failure, the primary cause of death in ALS. We expressed human FUS in rats to determine if FUS would induce ALS relevant respiratory changes to serve as an early stage disease indicator. The FUS expression was initiated in adult rats by way of an intravenously administered adeno-associated virus vector serotype 9 (AAV9) providing an adult onset model.

Results

The rats developed progressive motor impairments observed as early as 2–3 weeks post gene transfer. Respiratory abnormalities manifested 4–7 weeks post gene transfer including increased respiratory frequency and decreased tidal volume. Rats with breathing abnormalities also had arterial blood acidosis. Similar detailed plethysmographic changes were found in adult rats injected with AAV9 TDP-43. FUS gene transfer to adult rats yielded a consistent pre-clinical model with relevant motor paralysis in the early to middle stages and respiratory dysfunction at the end stage. Both FUS and TDP-43 yielded a similar consistent disease state.

Conclusions

This modeling method yields disease relevant motor and respiratory changes in adult rats. The reproducibility of the data supports the use of this method to study other disease related genes and their combinations as well as a platform for disease modifying interventional strategies.

Neurologic Causes of Acute Respiratory Dysfunction

Many neurologic diseases can cause acute respiratory decompensation, therefore a familiarity with these diseases is critical for any clinician managing patients with respiratory dysfunction. In this article, we review the anatomy of the respiratory system, focusing on the neurologic control of respiration. We discuss general mechanisms by which diseases of the peripheral and central nervous systems can cause acute respiratory dysfunction, and review the neurologic diseases which can adversely affect respiration. Lastly, we discuss the diagnosis and general management of acute respiratory impairment due to neurologic disease.

Progression from respiratory dysfunction to failure in late-onset Pompe disease

To identify determinants of respiratory disease progression in late-onset Pompe disease (LOPD), we studied relationships between pulmonary function, respiratory muscle strength, gas exchange, and respiratory control. Longitudinal evaluation of 22 LOPD patients (mean age 38 years) was performed at 6-month intervals for 6-24 months. Measurements included vital capacity (VC), maximum inspiratory pressure (MIP), maximum expiratory pressure (MEP), tidal volume (VT), dead space (VD), and ventilatory response to CO2. Although reduction in VC correlated with MIP and MEP (p < 0.0001), some patients had normal VC despite reduced MIP and MEP (5 [23%] and 9 [41%] patients, respectively). Daytime hypercapnia was associated with reduced VC (<60% predicted) and MIP (<40% predicted). Moreover, chronic hypercapnia was associated with elevated VD/VT (≥0.44) due to falling VT (≈300 ml), compatible with reduced efficiency of CO2 clearance. The presence of hypercapnia and/or ventilatory support was associated with reduced ventilatory responsiveness to CO2 (≤0.7 l/min/mmHg). We conclude that daytime hypercapnia, an indicator of chronic respiratory failure, is tightly linked to the degree of respiratory muscle weakness and severity of pulmonary dysfunction in LOPD patients. Reductions in CO2 clearance efficiency and ventilatory responsiveness may contribute to the development of chronic daytime hypercapnia.

Measuring Neuromuscular Junction Functionality in the SOD1(G93A) Animal Model of Amyotrophic Lateral Sclerosis

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease that leads to motor neuron degeneration, alteration in neuromuscular junctions (NMJs), muscle atrophy, and paralysis. To investigate the NMJ functionality in ALS we tested, in vitro, two innervated muscle types excised from SOD1^G93A transgenic mice at the end-stage of the disease: the Soleus, a postural muscle almost completely paralyzed at that stage, and the diaphragm, which, on the contrary, is functional until death. To this aim we employed an experimental protocol that combined two types of electrical stimulation: the direct stimulation and the stimulation through the nerve. The technique we applied allowed us to determine the relevance of NMJ functionality separately from muscle contractile properties in SOD1^G93A animal model. Functional measurements revealed that the muscle contractility of transgenic diaphragms is almost unaltered in comparison to control muscles, while transgenic Soleus muscles were severely compromised. In contrast, when stimulated via the nerve, both transgenic muscle types showed a strong decrease of the contraction force, a slowing down of the kinetic parameters, as well as alterations in the neurotransmission failure parameter. All together, these results confirm a severely impaired functionality in the SOD1^G93A neuromuscular junctions.

Sniff nasal inspiratory pressure as a prognostic factor of tracheostomy or death in amyotrophic lateral sclerosis

Forced vital capacity (FVC) shows limitations in detecting respiratory failure in the early phase of amyotrophic lateral sclerosis (ALS). In fact, mild-to-moderate respiratory muscle weakness may be present even when FVC is normal, and ALS patients with bulbar involvement might not be able to perform correctly the spirometry test. Sniff nasal inspiratory pressure (SNIP) is correlated with transdiaphragmatic strength. We evaluated SNIP at baseline as a prognostic factor of tracheostomy or death in patients with ALS. In a multidisciplinary tertiary care center for motorneuron disease, we enrolled 100 patients with ALS diagnosed with El Escorial criteria in the period between January 2006 and December 2010. Main outcome measures were tracheostomy or death. RECursive Partitioning and AMalgamation (RECPAM) analysis was also used to identify subgroups at different risks for the tracheostomy or death. Twenty-nine patients with ALS reached the outcome (12 died and 17 had tracheostomy). Using a multivariate model SNIP correctly classified the risk of the composite event within 1 year of follow-up with a continuous Net Reclassification Improvement cNRI of 0.58 (p = 0.03). Sex, Amyotrophic Lateral Sclerosis Functional Rating Scale revisited, site of onset, and FVC did not improve the classification of prognostic classes. SNIP ≤18 cmH2O identified the RECPAM class with the highest risk (Class 1, hazard ratio = 9.85, 95 % confidence interval: 2.67-36.29, p < 0.001). SNIP measured at baseline identified patients with ALS with initial respiratory failure. Finally, using only ALS patients with spinal onset of the disease, our findings were mostly overlapping with those reported in the models including the whole sample. At baseline, SNIP appeared to be the best predictor of death or tracheostomy within 1 year of follow-up. The measurement of SNIP in the early phase of the disease may contribute to identify patients with high risk of mortality or intubation. SNIP may also provide an additional tool for baseline stratification of patients with ALS in clinical trials.

Usefulness of phrenic latency and forced vital capacity in patients with ALS with latent respiratory dysfunction

OBJECTIVES

The pulmonary function test (PFT) is a non-invasive and easily available technique to assess respiratory function in patients with amyotrophic lateral sclerosis (ALS); however, patients with dyspnea sometimes show normal PFT findings. Herein, we investigated whether phrenic nerve conduction study (NCS) and PFT are useful to evaluate respiratory function of patients with ALS with normal value ranges in the PFT.

METHODS

We prospectively enrolled 34 patients with definite or probable ALS, who showed FVC (%) ⩾80 of predicted and 78 healthy subjects. PFT and phrenic NCS were performed with the measurement of forced vital capacity (FVC, %), forced expiratory volumes in 1s (FEV1, %), FEV1/FCV ratio (%), and phrenic compound muscle action potential amplitude, and latency.

RESULTS

Compared to healthy controls, ALS patients showed delayed phrenic nerve latency and the decrease of FVC (%) (p=0.006 and p<0.0001, respectively). ROC curve analysis demonstrated that phrenic latency (AUC=0.7655) and FVC (%) (AUC=0.8239) discriminated ALS patients from healthy subjects.

CONCLUSION

We demonstrated that ALS patients had early respiratory dysfunction, despite normal PFT findings.

SIGNIFICANCE

Phrenic latency and FVC (%) can be helpful to discriminate ALS patients with latent respiratory dysfunction from healthy subjects.

Sleep disordered breathing in isolated unilateral and bilateral diaphragmatic dysfunction

INTRODUCTION

The effect of isolated unilateral or bilateral diaphragmatic dysfunction (DD), in the absence of a generalized neuromuscular disorder, on sleep disordered breathing (SDB) is not well understood. The type of positive airway pressure (PAP) device needed to treat SDB in patients with isolated DD is also not well established.

METHODS

We retrospectively analyzed data on patients with isolated unilateral or bilateral DD who were referred for polysomnography (PSG) for clinical symptoms or abnormal oximetry between 1994 and 2006.

RESULTS

We found 66 patients who met criteria, of whom 74.2% were males with an average age of 58.8 ± 10.9 years. 56 had isolated unilateral DD, and 10 had isolated bilateral DD. All had significant SDB with an apnea-hypopnea index (AHI) of 26.6 ± 28.4. There were no significant differences in PSG measures, arterial blood gas analysis, pulmonary function tests, or echocardiographic data, except for lower maximal inspiratory pressure in patients with bilateral DD compared to unilateral DD (40.2% ± 17.8% vs. 57.7% ± 20.5%, p = 0.02). Control of SDB with continuous PAP (CPAP) was possible in only 37.9% of patients with the rest requiring bilevel PAP (BPAP). Patients with isolated bilateral DD and SDB were 6.8 times more likely to fail CPAP than those with unilateral DD (p = 0.03).

CONCLUSIONS

Most patients with isolated DD failed CPAP and required BPAP. Patients with bilateral DD were more likely to require BPAP than those with unilateral DD. Patients with isolated DD should be considered for in-lab titration to determine adequacy of therapy.

Improved survival with an ambulatory model of non-invasive ventilation implementation in motor neuron disease

Non-invasive ventilation (NIV) increases survival and quality of life in motor neuron disease (MND). NIV implementation historically occurred during a multi-day inpatient admission at this institution; however, increased demand led to prolonged waiting times. The aim of this study was to evaluate the introduction of an ambulatory model of NIV implementation. A prospective cohort study was performed. Inclusion criteria were referral for NIV implementation six months pre- or post-commencement of the Day Admission model. This model involved a 4-h stay to commence ventilation with follow-up in-laboratory polysomnography titration and outpatient attendance. Outcome measures included waiting time, hospital length of stay, adverse events and polysomnography data. Results indicated that after changing to the Day Admission model the median waiting time fell from 30 to 13.5 days (p < 0.04) and adverse events declined (4/17 pre- (three deaths, one acute admission) vs. 0/12 post-). Survival was also prolonged (median (IQR) 278 (51-512) days pre- vs 580 (306-1355) days post-introduction of the Day Admission model; hazard ratio 0.41, p = 0.04). Daytime PaCO2 was no different. In conclusion, reduced waiting time to commence ventilation and improved survival were observed following introduction of an ambulatory model of NIV implementation in people with MND, with no change in the effectiveness of ventilation.

Breathing new life into treatment advances for respiratory failure in amyotrophic lateral sclerosis patients

SUMMARY In the last three decades, improvements in respiratory management are responsible for increasing survival and improving quality of life for amyotrophic lateral sclerosis (ALS) patients. Nowadays, ALS patients with respiratory involvement are offered a support treatment other than the traditional respiratory palliative care. Knowledge about available respiratory support potentialities is essential for appropriate, customized and effective treatment of ALS, which should probably be started sooner than the conventional approach. There is evidence supporting that respiratory support has a larger impact than riluzole on survival. Noninvasive ventilation is essential in the treatment of ALS patients with respiratory involvement. In this article methods to determine respiratory failure in ALS, mechanical invasive and noninvasive ventilation, telemetry, diaphragm pacing, cough aids and respiratory exercise are reviewed, after a brief overlook of respiratory insufficiency in ALS.

Breathing and the nervous system

Breathing requires complex interactions of the central and peripheral nervous systems with the respiratory system. It involves cortical (volitional) as well as subcortical (automatic) output. Cortical output is mainly through the corticospinal tract, whereas the brainstem sends signals via the reticulospinal tract. Groups of nuclei in the brainstem (pneumotaxic center, dorsal and ventral respiratory group), situated in the pons and medulla, function as rhythm generators. Some of these nuclei have intrinsic pacemaker activity; however, their output is affected extensively by various chemical (through aortic and carotid bodies), mechanical (stretch reflexes), and neural feedbacks from the peripheral nervous system involving cranial nerves V, VII, IX, X, and XI. Brainstem nuclei also have central chemoreceptors that detect changes in serum carbon dioxide and pH. Various neurologic disorders such as stroke or neurodegenerative diseases (Parkinson's disease, multiple system atrophy) can adversely affect respiration and may even be the first sign of disease onset. Clinicians should have a better understanding of this complex but important physiological process to better appreciate pathologies affecting it. Future research is needed to enhance our understanding of this intricate process.

Common mechanisms of compensatory respiratory plasticity in spinal neurological disorders

In many neurological disorders that disrupt spinal function and compromise breathing (e.g. ALS, cervical spinal injury, MS), patients often maintain ventilatory capacity well after the onset of severe CNS pathology. In progressive neurodegenerative diseases, patients ultimately reach a point where compensation is no longer possible, leading to catastrophic ventilatory failure. In this brief review, we consider evidence that common mechanisms of compensatory respiratory plasticity preserve breathing capacity in diverse clinical disorders, despite the onset of severe pathology (e.g. respiratory motor neuron denervation and/or death). We propose that a suite of mechanisms, operating at distinct sites in the respiratory control system, underlies compensatory respiratory plasticity, including: (1) increased (descending) central respiratory drive, (2) motor neuron plasticity, (3) plasticity at the neuromuscular junction or spared respiratory motor neurons, and (4) shifts in the balance from more to less severely compromised respiratory muscles. To establish this framework, we contrast three rodent models of neural dysfunction, each posing unique problems for the generation of adequate inspiratory motor output: (1) respiratory motor neuron death, (2) de- or dysmyelination of cervical spinal pathways, and (3) cervical spinal cord injury, a neuropathology with components of demyelination and motor neuron death. Through this contrast, we hope to understand the multilayered strategies used to "fight" for adequate breathing in the face of mounting pathology.

Ventilatory control in ALS

Amyotrophic lateral sclerosis (ALS) is a fatal, progressive neurodegenerative disease. ALS selectively causes degeneration in upper and lower (spinal) motor neurons, leading to muscle weakness, paralysis and death by ventilatory failure. Although ventilatory failure is generally the cause of death in ALS, little is known concerning the impact of this disorder on respiratory motor neurons, the consequences of respiratory motor neuron cell death, or the ability of the respiratory control system to "fight back" via mechanisms of compensatory respiratory plasticity. Here we review known effects of ALS on breathing, including possible effects on rhythm generation, respiratory motor neurons, and their target organs: the respiratory muscles. We consider evidence for spontaneous compensatory plasticity, preserving breathing well into disease progression despite dramatic loss of spinal respiratory motor neurons. Finally, we review current and potential therapeutic approaches directed toward preserving the capacity to breathe in ALS patients.

Monitoring respiratory muscle strength assists in early diagnosis of respiratory dysfunction as opposed to the isolated use of pulmonary function evaluation in amyotrophic lateral sclerosis

ObjectiveIt was study the relationship between respiratory muscle strength and forced vital capacity (FVC) in patients with amyotrophic lateral sclerosis (ALS) versus healthy subjects.MethodsPulmonary function and respiratory muscle strength [maximal inspiratory (PImax), maximal expiratory (PEmax) and sniff nasal inspiratory pressure (SNIP)] were assessed in patients with ALS and healthy subjects, matched using cutoffs established in the literature for impaired pulmonary function and respiratory muscle weakness.ResultsTwenty-eight ALS patients and 28 healthy subjects were studied. We found sensitivity and specificity for PImax, PEmax and SNIP of 75/58%, 81/67% and 75/67%. The Receiver Operating Characteristic curve (ROC curve) indicated that the variables PImax, PEmax and SNIP can identify differences in respiratory muscle strength between ALS and healthy individuals at 0.89, 0.9 and 0.82, respectively. A positive correlation was recorded between FVC (%) versus SNIP, PImax and PEmax.ConclusionIn ALS, monitoring respiratory muscle strength assists in early diagnosis of respiratory dysfunction as opposed to the isolated use of FVC.

Spinal anesthetic management for discectomy in a patient with amyotrophic lateral sclerosis -A case report-

Amyotrophic lateral sclerosis (ALS), also referred to as Lou Gehrig's disease, is a degenerative disorder of motor neuron system of the spinal cord and the cortical neuron. Patients with ALS present a unique challenge to the anesthesiologist. Respiratory muscle weakness, for instance, can result in trouble with proper breathing after general anesthesia. We report a case of spinal anesthesia for discectomy in a patient with ALS.

Respiratory therapies for amyotrophic lateral sclerosis: a primer

Respiratory complications are a common cause of morbidity and mortality in amyotrophic lateral sclerosis (ALS). Treatment of respiratory insufficiency with noninvasive ventilation (NIV) improves ALS patients' quality of life and survival. Evidence-based practice guidelines for the management of ALS patients recommend treatment of respiratory insufficiency with NIV as well as consideration of insufflation/exsufflation to improve clearance of airway secretions. Despite these recommendations respiratory therapies remain underused. In this review we provide a practical guide for the clinician to prescribe and manage respiratory therapies for the patient with ALS.

Protocol for diaphragm pacing in patients with respiratory muscle weakness due to motor neurone disease (DiPALS): a randomised controlled trial

Background

Motor neurone disease (MND) is a devastating illness which leads to muscle weakness and death, usually within 2-3 years of symptom onset. Respiratory insufficiency is a common cause of morbidity, particularly in later stages of MND and respiratory complications are the leading cause of mortality in MND patients. Non Invasive Ventilation (NIV) is the current standard therapy to manage respiratory insufficiency. Some MND patients however do not tolerate NIV due to a number of issues including mask interface problems and claustrophobia. In those that do tolerate NIV, eventually respiratory muscle weakness will progress to a point at which intermittent/overnight NIV is ineffective. The NeuRx RA/4 Diaphragm Pacing System was originally developed for patients with respiratory insufficiency and diaphragm paralysis secondary to stable high spinal cord injuries. The DiPALS study will assess the effect of diaphragm pacing (DP) when used to treat patients with MND and respiratory insufficiency.

Method/Design

108 patients will be recruited to the study at 5 sites in the UK. Patients will be randomised to either receive NIV (current standard care) or receive DP in addition to NIV. Study participants will be required to complete outcome measures at 5 follow up time points (2, 3, 6, 9 and 12 months) plus an additional surgery and 1 week post operative visit for those in the DP group. 12 patients (and their carers) from the DP group will also be asked to complete 2 qualitative interviews.

Discussion

The primary objective of this trial will be to evaluate the effect of Diaphragm Pacing (DP) on survival over the study duration in patients with MND with respiratory muscle weakness. The project is funded by the National Institute for Health Research, Health Technology Assessment (HTA) Programme (project number 09/55/33) and the Motor Neurone Disease Association and the Henry Smith Charity. Trial Registration: Current controlled trials ISRCTN53817913. The views and opinions expressed therein are those of the authors and do not necessarily reflect those of the HTA programme, NIHR, NHS or the Department of Health.