Effects of alterations in pulmonary function and sleep variables on survival in patients with amyotrophic lateral sclerosis

Perioperative Management in Neuromuscular Diseases: A Narrative Review

Patients with neuromuscular diseases are particularly vulnerable in the perioperative period to the development of pulmonary and cardiac complications, or medication side effects. These risks could include hypoventilation, aspiration pneumonia, exacerbation of underlying cardiomyopathy, arrhythmias, adrenal insufficiency, prolonged neuromuscular blockade, issues related to thermoregulation, rhabdomyolysis, malignant hyperthermia, or prolonged mechanical ventilation. Interventions at each of the perioperative stages can be implemented to mitigate these risks. A careful pre-operative evaluation may help identify risk factors so that appropriate interventions are initiated, including cardiology consultation, pulmonary function tests, initiation of noninvasive ventilation, or implementation of preventive measures. Important intraoperative issues include positioning, airway and anesthetic management, and adequate ventilation. The postoperative period may require correction of electrolyte abnormalities, control of secretions with medications, manual or mechanical cough assistance, avoiding the risk of reintubation, judicious pain control, and appropriate medication management. The aim of this review is to increase awareness of the particular surgical challenges in this vulnerable population, and guide the clinician on the various evaluations and interventions that may result in a favorable surgical outcome.

Optimal Noninvasive Medicare Access Promotion: Patients with Thoracic Restrictive Diseases A Technical Expert Panel Report from the American College of Chest Physicians, the American Association for Respiratory Care, the American Academy of Sleep Medicine, and the American Thoracic Society

The existing coverage criteria for Non-Invasive Ventilation (NIV) do not recognize the benefits of early initiation of NIV for those with Thoracic Restrictive Disease (TRD) and do not address the unique needs for daytime support as the patient's progress to ventilator dependence. This document summarizes the work of the Thoracic Restrictive Disease Technical Expert Panel working group. The most pressing current coverage barriers identified were: 1) Delays in implementing NIV treatment 2) Lack of coverage for many non-progressive Neuro-Muscular Disease (NMD) and 3) Lack of clear policy indications for Home -Mechanical Ventilation (HMV) Support in TRD. To best address these issues we make the following key recommendations: 1) Given the need to encourage early initiation of NIV with Bi-level Positive Airway Pressure (BPAP) devices, we recommend that symptoms be considered as a reason to initiate therapy even at mildly reduced FVC's.; 2) Broaden CO2 measurements to include surrogates such as transcutaneous, end-tidal or Venous Blood Gas (VBG); 3) Expand the diagnostic category to include Phrenic Nerve injuries and Disorders of Central Drive; 4) Allow a BPAP device to be advanced to an HMV when the VC is <30% or to address severe daytime respiratory symptoms; 5) Provide an additional HMV when the patient is ventilator dependent with use >18 hours/ day. Adoption of these proposed recommendations would result in the right device, at the right time, for the right type of patients with hypoventilation syndromes.

Respiratory parameters on diagnostic sleep studies predict survival in patients with amyotrophic lateral sclerosis

OBJECTIVE

In amyotrophic lateral sclerosis (ALS), respiratory muscle involvement and sleep-disordered breathing relate to worse prognosis. The present study investigated whether respiratory outcomes on first-ever sleep studies predict survival in patients with ALS, specifically taking into account subsequent initiation of non-invasive ventilation (NIV).

METHODS

From patients with ALS, baseline sleep study records, transcutaneous capnometry, early morning blood gas analysis, survival data and clinical disease characteristics were retrospectively analyzed. Patients were stratified according to whether enduring NIV was consecutively established ("NIV(+)") or not ("NIV(-)").

RESULTS

Among the study cohort (n = 158, 72 female, 51 with bulbar onset ALS, 105 deceased) sleep-disordered breathing was present at baseline evaluation in 97 patients. Early morning base excess (EMBE) > 2 mmol/l predicted nocturnal hypercapnia. Ninety-five patients were NIV(+) and 63 were NIV(-). Survival from baseline sleep studies was significantly reduced in NIV(-) but not in NIV(+) patients with nocturnal CO₂ tension ≥ 50 mmHg, apnea hypopnea index ≥ 5/h, and EMBE > 2 mmol/l. Hazard ratio for EMBE > 2 mmol/l was increased in NIV(-) patients only, and EMBE independently predicted survival in both NIV(-) and NIV(+) patients. Furthermore, EMBE on baseline sleep studies was the only predictor for survival from symptom onset, and hazard ratio for shorter survival was markedly higher in the NIV(-) than the NIV(+) group (2.85, p = 0.005, vs. 1.71, p = 0.042).

INTERPRETATION

In patients with ALS, EMBE > 2 mmol/l predicts nocturnal hypercapnia and shorter survival. Negative effects of sleep-disordered breathing on survival are statistically abolished by sustained NIV.

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.

Why individuals with cerebral palsy are at higher risk for respiratory complications from COVID-19

Respiratory dysfunction is a leading cause of morbidity and mortality in individuals with cerebral palsy (CP). In children and adults with CP, movement and physical function is always affected. Yet, many clinicians overlook potential for impaired movement and function of the diaphragm muscle (DIAm) in individuals with CP. Since individuals with pre-existing respiratory disorders are at greater risk for respiratory complications if they contract COVID-19, understanding potential risks to individuals with CP is important. In this review we present research on respiratory function and DIAm force generation in children with CP. We compare this clinical work to basic science research investigating phrenic motor neuron and DIAm motor unit dysfunction in an animal model with CP symptoms, the spa mouse. Finally, we integrate the clinical and basic science work in respiratory function in CP, discussing potential for individuals with CP to have severe respiratory symptoms from COVID-19.

Sleep disordered breathing in motor neurone disease

Motor neurone disease (MND) is a neurodegenerative disease defined by axonal loss and gliosis of upper and lower motor neurones in the motor cortex, lower brainstem nuclei and ventral horn of the spinal cord. MND is currently incurable and has a poor prognosis, with death typically occurring 3 to 5 years after disease onset. The disease is characterised by rapidly progressive weakness leading to paralysis, fasciculations, bulbar symptoms (including dysarthria and dysphagia) and respiratory compromise. Respiratory complications arise as a result of weakness of upper airway (pharyngeal and laryngeal) muscles and respiratory muscles (diaphragm, intercostal and accessory muscles) leading to respiratory failure. Due to early involvement of respiratory muscles in MND, sleep disordered breathing (SDB) occurs at a higher frequency than compared to the general population. SDB usually precedes daytime respiratory symptoms and chronic respiratory failure. It significantly impacts upon patients' quality of life and survival and its presence may predict prognosis. Managing SDB in MND with non-invasive ventilation (NIV) improves quality of life and survival. Early identification and management of SDB in MND patients is therefore crucial. This update will review assessments of respiratory muscle function, types of SDB and the effects of NIV in patients with MND.

Maximum inspiratory pressure as a clinically meaningful trial endpoint for neuromuscular diseases: a comprehensive review of the literature

Respiratory muscle strength is a proven predictor of long-term outcome of neuromuscular disease (NMD), including amyotrophic lateral sclerosis, Duchenne muscular dystrophy, and spinal muscular atrophy. Maximal inspiratory pressure (MIP), a sensitive measure of respiratory muscle strength, one of several useful tests of respiratory muscle strength, is gaining interest as a therapeutic clinical trial endpoint for NMD. In this comprehensive review we investigate the use of MIP as a measure of respiratory muscle strength in clinical trials of therapeutics targeting respiratory muscle, examine the correlation of MIP with survival, quality of life, and other measures of pulmonary function, and outline the role of MIP as a clinically significantly meaningful outcome measure. Our analysis supports the utility of MIP for the early evaluation of respiratory muscle strength, especially of the diaphragm, in patients with NMD and as a surrogate endpoint in clinical trials of therapies for NMD.

Noninvasive ventilation in amyotrophic lateral sclerosis: effects on sleep quality and quality of life

OBJECTIVES

Little is known about the effects of noninvasive ventilation (NIV) on sleep quality in amyotrophic lateral sclerosis (ALS). We aim to evaluate the long-term effects of NIV on sleep quality and quality of life in patients with ALS.

METHODS

In this prospective observational study, 13 ALS patients were followed for one year after initiating NIV. We evaluated sleep quality, quality of life and functional status with several questionnaires: Epworth sleepiness Scale (ESS), Pittsburg sleep quality index (PSQI), Short Form 36 Health Questionnaire (SF-36), McGill Quality of Life questionnaire (McGillQoL) and revised Amyotrophic Lateral Sclerosis Functional Rating Scale scores (ALSFRS-R).

RESULTS

Median and interquartile range (IQR) at the start of NIV was 59 (53-65) years. The ALSFRS-R at start was 30 (24-37) (median, IQR), with three patients having severe bulbar impairment (ALSFRS-R-bulbar ≤ 9). The P_aCO₂ at start of NIV treatment was 48 (43-52) mmHg (median, IQR). During the one-year follow-up period, a significant decrease in the ALSFRS-R was observed. The impact of NIV in a short term (1 month) revealed a statistically significant decrease in ESS, decrease in total PSQI and of four PSQI subscales and improvement of almost all subscales of the McGill questionnaire. Long-term analyses (9 months to 1 year) revealed that amelioration in ESS and total PSQI was sustained.

CONCLUSION

We conclude that accurately titrated NIV in ALS patients can stabilize sleep quality and quality of life for at least one year, despite significant disease progression.

The Prognostic Role of Obstructive Sleep Apnea at the Onset of Amyotrophic Lateral Sclerosis

BACKGROUND/OBJECTIVE

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease characterized by the progressive loss of central and peripheral motor neurons. Some studies have found discordant data in the presence of sleep apnea in ALS patients. An obstructive component also occurs with upper airways hypotonia and muscle weakness that may result in an excessive reduction of airway lumen, leading to obstructive sleep apnea (OSA). The aim of this study was to assess the role of obstructive apneic events at disease onset in the ALS prognosis.

METHODS

A longitudinal retrospective study was conducted on 42 clinically diagnosed ALS patients. The study population was divided into 2 groups according to their obstructive apnea/hypopnea index (AHIo): group 1 consisted of 20 patients with an AHIo ≥5 and group 2 consisted of 22 patients with an AHIo <5. Both groups were compared with regard to demographic, polygraphic, and respiratory function parameters as well as ALS characteristics (bulbar onset, time between onset and first check-up, time between diagnosis and first check-up, time between first check-up and death or tracheostomy).

RESULTS

The mean survival in ALS patients with an AHIo ≥5 was significantly shorter than in ALS without OSA (p = 0.0237). The sniff nasal inspiratory pressure test was significantly correlated with AHIo, time of oxyhemoglobin saturation below 90% and the oxyhemoglobin desaturation index (p < 0.0001).

CONCLUSIONS

Our study highlights the importance of an early diagnosis of OSA in ALS patients, allowing the identification of ALS patients with an OSA phenotype (AHIo ≥5), who are characterized by a worse prognosis.

Assessment of pulmonary function in amyotrophic lateral sclerosis: when can polygraphy help evaluate the need for non-invasive ventilation?

BACKGROUND

Non-invasive positive-pressure ventilation (NPPV) is an established, effective, long-term treatment for patients with amyotrophic lateral sclerosis (ALS), but the correct indicators for the establishment of NPPV have not been defined.

METHODS

In this retrospective study, records (spirometry, nocturnal polygraphy, nocturnal blood gases) of 131 patients with ALS were reviewed in order to evaluate the role of polygraphy for prediction of respiratory failure in ALS.

RESULTS

The patient group reporting with versus without dyspnoea had significantly lower values on the revised ALS-Functional Rating Scale (ALSFRS-R), vital capacity (VC), forced VC (FVC), arterial oxygen saturation and arterial oxygen tension readings, including a higher apnoea-hypopnoea index. 23 patients, who did not report about dyspnoea, had an FVC of <75%. Nocturnal hypoventilation was observed in 67% of the patients with ALS independent of their ALSFRS-R. The patient group with nocturnal hypoventilation was characterised by a significantly lower VC, FVC and maximal static inspiratory pressure compared with the group without nocturnal hypoventilation. However, also in the absence of nocturnal hypoventilation, 8 patients had a VC <50% as predicted.

DISCUSSION

Our study shows that in patients not reporting dyspnoea and having an FVC of >75%, nocturnal hypoventilation was observed in nearly every second patient. Therefore, for the question of whether NPPV should be initiated, polygraphy does not provide useful additional information if the FVC is already <75% as predicted. However, in patients with more or less normal lung function parameters or where lung spirometry cannot perform adequately (eg, bulbar ALS), it can provide sufficient evidence for the need of NPPV.

Altered Metabolic Homeostasis in Amyotrophic Lateral Sclerosis: Mechanisms of Energy Imbalance and Contribution to Disease Progression

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease characterized by the death of motor neurones, which leads to paralysis and death in an average of 3 years following diagnosis. The cause of ALS is unknown, but there is substantial evidence that metabolic factors, including nutritional state and body weight, affect disease progression and survival. This review provides an overview of the characteristics of metabolic dysregulation in ALS focusing on mechanisms that lead to disrupted energy supply (at a whole-body and cellular level) and altered energy expenditure. We discuss how a decrease in energy supply occurs in parallel with an increase in energy demand and leads to a state of chronic energy deficit which has a negative impact on disease outcome in ALS. We conclude by presenting potential and tested strategies to compensate for, or correct this energy imbalance, and speculate on promising areas for further research.

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.

Practical respiratory management in amyotrophic lateral sclerosis: evidence, controversies and recent advances

In amyotrophic lateral sclerosis, the onset of respiratory muscle weakness is silent, but survival following symptom recognition may only be a few weeks. Consequently, respiratory function and symptoms should be assessed every 2-3 months. Noninvasive ventilation improves symptoms, quality of life and survival, without increasing carer burden. Lung volume recruitment helps to reverse and prevent atelectasis, improving gas exchange, while techniques to enhance sputum clearance reduce the risk of mucus plugging and lower respiratory tract infections. When noninvasive support fails, often due to severe bulbar impairment, tracheostomy ventilation prolongs life. Most patients receiving tracheostomy ventilation at home report satisfactory quality of life, but at the expense of high carer burden. Diaphragmatic pacing is associated with an increased risk of death.

Neuromuscular disorders and sleep in critically ill patients

Sleep-disordered breathing (SDB) is a frequent presenting manifestation of neuromuscular disorders and can lead to significant morbidity and mortality. If not recognized and addressed early in the clinical course, SDB can lead to clinical deterioration with respiratory failure. The pathophysiologic basis of SDB in neuromuscular disorders, clinical features encountered in specific neuromuscular diseases, and diagnostic and management strategies for SDB in neuromuscular patients in the critical care setting are reviewed. Noninvasive positive pressure ventilation has been a crucial advance in critical care management, improving sleep quality and often preventing or delaying mechanical ventilation and improving survival in neuromuscular patients.

Amyotrophic lateral sclerosis: impact of pulmonary follow-up and mechanical ventilation on survival. A study of 114 cases

OBJECTIVE

To study the impact of ventilatory management and treatment on the survival of patients with amyotrophic lateral sclerosis (ALS).

METHOD

Retrospective analysis of 114 consecutive patients admitted to a general hospital, evaluating demographic data, type of presentation, clinical management, treatment with mechanical ventilation and survival.

STATISTICS

descriptive and Kaplan-Meier estimator.

RESULTS

Sixty four patients presented initial bulbar involvement. Overall mean survival after diagnosis was 28.0 months (95%CI, 21.1-34.8). Seventy patients were referred to the pulmonary specialist (61.4%) and 43 received non-invasive ventilation (NIV) at 12.7 months (median) after diagnosis. Thirty seven patients continued to receive NIV with no subsequent invasive ventilation. The mean survival of these patients was 23.3 months (95%CI, 16.7-28.8), higher in those without bulbar involvement, although below the range of significance. Survival in the 26 patients receiving programmed NIV was higher than in the 11 patients in whom this was indicated without prior pulmonary assessment (considered following diagnosis, P<.012, and in accordance with the start of ventilation, P<.004). A total of 7 patients were treated invasively; mean survival in this group was 72 months (95%CI, 14.36-129.6), median 49.6±17.5 (95%CI, 15.3-83.8), and despite the difficulties involved in home care, acceptance and tolerance was acceptable.

CONCLUSIONS

Long-term mechanical ventilation prolongs survival in ALS. Programmed pulmonary assessment has a positive impact on survival of ALS patients and is key to the multidisciplinary management of this disease.

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.

Effects of noninvasive ventilation on sleep outcomes in amyotrophic lateral sclerosis

STUDY OBJECTIVES

The objective was to study the effects on noninvasive ventilation on sleep outcomes in patient with ALS, specifically oxygenation and overall sleep quality.

METHODS

Patients with ALS who met criteria for initiation of NIV were studied with a series of 2 home PSG studies, one without NIV and a follow-up study while using NIV. Primary outcome was a change in the maximum overnight oxygen saturation; secondary outcomes included change in mean overnight oxygen saturation, apnea and hypopnea indexes, sleep latency, sleep efficiency, sleep arousals, and sleep architecture.

RESULTS

A total of 94 patients with ALS were screened for eligibility; 15 were enrolled; and 12 completed study procedures. Maximum overnight oxygen saturation improved by 7.0% (p = 0.01) and by 6.7% during REM sleep (p = 0.02) with NIV. Time spent below 90% oxygen saturation was also significant-ly better with NIV (30% vs 19%, p < 0.01), and there was trend for improvement in mean overnight saturation (1.5%, p = 0.06). Apnea index (3.7 to 0.7), hypopnea index (6.2 to 5.7), and apnea hypopnea index (9.8 to 6.3) did not significantly improve after introducing NIV. NIV had no effect on sleep efficiency (mean change 10%), arousal index (7 to 12), or sleep stage distribution (Friedman chi-squared = 0.40).

CONCLUSIONS

NIV improved oxygenation but showed no significant effects on sleep efficiency, sleep arousals, restful sleep, or sleep architecture. The net impact of these changes for patients deserves further study in a larger group of ALS patients.

Respiratory muscle assessment in acute exacerbation of chronic obstructive pulmonary disease and its role as a potential biomarker

BACKGROUND

AECOPD is a life threatening condition for patients with chronic obstructive pulmonary disease (COPD) and lack of specific biomarker hinders effective management. Sputum, blood, breath and urinary biomarkers have all been investigated. We measured maximum respiratory pressure post exacerbation once the patient was compliant with the test and after 6 weeks, to assess any correlations.

METHODS AND RESULTS

The maximum pressures were measured using a closed circuit spirometer with a clean rubber mouthpiece properly placed with the patients lips sealed around it. Patients were properly instructed to exhale slowly and completely, then inspire with maximum possible effort and advised to keep it for nearly 1.5 s for maximum inspiratory pressure (MIP). For maximum expiratory pressures (MEP) patients were instructed to inspire slowly and completely, then expire forcefully with maximum effort. With the recorded values TTI (time tension index) was calculated. This was repeated again after 6 weeks. Using Pearsons correlation coefficient we found that MIP had a negative correlation with TTI and a positive correlation with FEV1. FEV1 had a positive correlation with FVC. MEP showed no significant correlation with TTI, but a positive correlation with FEV1.

CONCLUSION

Acute exacerbations of COPD has a profound effect on the respiratory musculature especially the expiratory muscles but the maximum pressures are not specific enough to be prognostic markers. It might be worthwhile studying transformations of the respiratory musculature at the molecular level. More studies must be conducted to find a specific marker to aid in the management of the condition.

Sleep–wake problems in patients with amyotrophic lateral sclerosis: implications for patient management

SUMMARY Sleep–wake problems are frequent, although unrecognized, complications of amyotrophic lateral sclerosis (ALS). Sleep disorders such as insomnia, sleep-disordered breathing and restless legs syndrome have all been reported in patients with ALS, despite the limited number of studies and the small populations investigated so far. Sleep disturbances gradually worsen with disease progression, suggesting a relationship between the severity of disease and the neurodegenerative process. However, poor sleep can also be a consequence of several disturbances such as anxiety, depression, pain, choking, sialorrhea, fasciculations, cramps, nocturia and the inability to get comfortable and move freely in bed. Sleep disorders may have many reflections on patients with ALS, including excessive daytime somnolence, fatigue, impaired cognition, reduced quality of life and survival. This article reviews the recent literature on sleep–wake problems in patients with ALS, focusing on the implications for patient management.

Sleep breathing disorders in 40 Italian patients with Myotonic dystrophy type 1

The aim of this study was to estimate the prevalence and nature of sleep breathing disorders in Myotonic dystrophy type 1 (DM1). We wanted to determine whether there is a relationship between sleep breathing disorders and clinical parameters such as pulmonary function, degree of neuromuscular impairment, daytime sleepiness, and fatigue. This will help assess the prevalence of DM1 patients requiring nocturnal ventilatory treatments. We studied a random sample of 40 unrelated patients and found that 22/40 patients had obstructive sleep apnoea. Of these 22 patients, five showed also periodic breathing and four showed sleep hypoventilation. Nine patients were put on nocturnal ventilation following clinical and instrumental evaluations. Our study reveals that obstructive sleep apnoea is very common in these patients, but cannot be predicted on the basis of clinical-neurological features and diurnal functional respiratory tests. Our data emphasize that a periodical evaluation by polysomnography should be mandatory to ascertain, and treat if necessary, the presence of obstructive sleep apnoea, periodic breathing or nocturnal hypoventilation.

Home mechanical ventilation: a Canadian Thoracic Society clinical practice guideline

Increasing numbers of patients are surviving episodes of prolonged mechanical ventilation or benefitting from the recent availability of userfriendly noninvasive ventilators. Although many publications pertaining to specific aspects of home mechanical ventilation (HMV) exist, very few comprehensive guidelines that bring together all of the current literature on patients at risk for or using mechanical ventilatory support are available. The Canadian Thoracic Society HMV Guideline Committee has reviewed the available English literature on topics related to HMV in adults, and completed a detailed guideline that will help standardize and improve the assessment and management of individuals requiring noninvasive or invasive HMV. The guideline provides a disease-specific review of illnesses including amyotrophic lateral sclerosis, spinal cord injury, muscular dystrophies, myotonic dystrophy, kyphoscoliosis, post-polio syndrome, central hypoventilation syndrome, obesity hypoventilation syndrome, and chronic obstructive pulmonary disease as well as important common themes such as airway clearance and the process of transition to home. The guidelines have been extensively reviewed by international experts, allied health professionals and target audiences. They will be updated on a regular basis to incorporate any new information.

Sleep characteristics of amyotrophic lateral sclerosis in patients with preserved diaphragmatic function

There are a number of sleep studies in amyotrophic lateral sclerosis (ALS), in general including a heterogeneous population of patients. We aimed to study sleep in a population of selected ALS patients by investigating nocturnal polysomnography (PSG) characteristics in ALS patients with normal respiratory function tests and preserved diaphragmatic innervation. Ninety-two ALS patients were screened by percutaneous nocturnal oximetry (PNO). Eleven ALS patients with normal respiratory function tests, phrenic motor responses and preserved motor units on needle electromyography of the diaphragm, but abnormal PNO, were selected for PSG. REM was present in eight patients, but normal in only three. Three patients had mixed apnoea-hypopnoea, severe in one. Seven showed a pattern of periodic mild O(2) desaturation, which occurred in REM 3, REM and NREM 3 and in NREM sleep 1. One patient studied six months later had more severe changes in the second evaluation. In conclusion, the most common sleep disordered breathing was periodic mild O(2) desaturation independent of the sleep stage (REM, NREM). This might represent central drive dysfunction or respiratory muscle fatigue in ALS.

Early treatment with noninvasive positive pressure ventilation prolongs survival in Amyotrophic Lateral Sclerosis patients with nocturnal respiratory insufficiency

BACKGROUND

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease, which rapidly leads to chronic respiratory failure requiring mechanical ventilation. Currently, forced vital capacity (FVC) < 50% is considered as physiologic marker for admitting patients to Noninvasive Positive Pressure Ventilation (NPPV) intervention, although it has been recently shown the median survival of patients with baseline FVC < 75% much shorter than median survival of patients with baseline FVC > 75%, independently by any treatment.

AIM

To assess the role of NPPV in improving outcome of ALS, a retrospective analysis was performed to investigate 1 year survival of ALS patients with FVC < 75% and nocturnal respiratory insufficiency, treated with NPPV, compared to a well-matched population of ALS patients, who refused or was intolerant to NPPV.

METHODS

We investigated seventy-two consecutive ALS patients who underwent pulmonary function test. Forty-four presented a FVC > 75% and served as control group. Twenty-eight patients presented a FVC < 75% and showed, at polysomnography analysis, nocturnal respiratory insufficiency, requiring NPPV; sixteen were treated with NPPV, while twelve refused or were intolerant.

RESULTS

Increased survival rate at 1 year in patients with FVC < 75% treated with NPPV, as compared to those who refused or could not tolerate NPPV (p = 0.02), was observed. The median rate of decline in FVC% was slower in NPPV patients than in patients who did not use NPPV (95% CI: 0.72 to 1.85; p < 0.0001).

CONCLUSION

This report demonstrates that early treatment with NPPV prolongs survival and reduces decline of FVC% in ALS.

Diaphragm training in amyotrophic lateral sclerosis

There is a continued need for therapies to improve respiratory function and quality of life in patients with amyotrophic lateral sclerosis. In this pilot trial, we studied 8 subjects with amyotrophic lateral sclerosis and respiratory involvement. We measured respiratory function and quality of life at baseline. We then taught subjects diaphragm training, a method of breath control designed to improve respiratory muscle strength and efficiency. We repeated measures of respiratory function and quality of life 6 and 12 weeks later. There was no significant improvement in any outcome measure after instituting diaphragm training. There was a nonsignificant trend toward a slower rate of decline in respiratory function in those subjects who mastered the technique; however, only half the subjects were able to successfully change their pattern of breathing. A larger study of this technique is warranted; however, in determining the sample size for a larger study, the difficulty for patients in mastering the technique must be taken into consideration.

Respiratory treatment of amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis is a progressive neurodegenerative disease with no known cure. The major cause of mortality and major morbidities is related to the effects of the disease on the muscles of the respiratory system (ie, the inspiratory, expiratory, and upper airway muscles). Dyspnea, swallowing difficulties, sialorrhea, and impaired cough are all symptoms that can be palliated through pharmacologic and nonpharmacologic means. Noninvasive positive pressure ventilation, in particular, is a technique that not only relieves dyspnea but may also extend the lives of patients who have this disease. It should be offered to all patients who have amyotrophic lateral sclerosis with a forced vital capacity of less than 50 percent.

Management of respiration in MND/ALS patients: an evidence based review

This systematic review comprises an objective appraisal of the evidence in regard to the management of respiration in patients with motor neuron disease (MND/ALS). Studies were identified through computerised searches of 32 databases. Internet searches of websites of drug companies and MND/ALS research web sites, 'snow balling' and hand searches were also employed to locate any unpublished study or other 'grey literature' on respiration and MND/ALS. Since management of MND/ALS involves a number of health professionals and care workers, searches were made across multiple disciplines. No time frame was imposed on the search in order to increase the probability of identifying all relevant studies, although there was a final limit of March 2005. Recommendations for patient and carer-based guidelines for the clinical management of respiration for MND/ALS patients are suggested on the basis of qualitative analyses of the available evidence. However, these recommendations are based on current evidence of best practice, which largely comprises observational research and clinical opinion. There is a clear need for further evidence, in particular randomised and non-randomised controlled trials on the effects of non-invasive ventilation and additional larger scale cohort studies on the issues of initial assessment of respiratory symptoms, and management and timing of interventions.

[Long term domiciliary mechanical ventilation in patients with neuromuscular disease (indications, establishment and follow up)]

Neuromuscular diseases represent a heterogeneous group of pathologies which common feature is the development of a restrictive ventilatory failure.

BACKGROUND

Respiratory insufficiency of neuromuscular origin manifests itself by functional symptoms that must be carefully searched for in the history, such as headaches, sleep disorders, or dyspnoea of effort, sometimes very mild, or in severe cases associated with orthopnoea. Follow up should be multi-disciplinary. On the respiratory level regular measurement of blood gases, vital capacity, maximum inspiratory and expiratory pressures as well as sleep studies, will detect the criteria for mechanical ventilation (hypercarbia > 45 mm Hg, nocturnal desaturation < 88%, vital capacity < 60%, PImax < 60 cm H2O).

STATE OF THE ART

The establishment of mechanical ventilation is a major decision for patients with neuromuscular disease because of the important physical, psychological, social and sometimes financial consequences. The patients and their family must be instructed precisely in order to obtain the best possible observation and compliance. The establishment requires a stay in hospital of several days to optimise the choice of ventilator, its settings, and connections. The link with the organisation managing the domiciliary ventilation is fundamental in ensuring follow up after discharge from hospital. Techniques of cough assistance must be taught to each neuromuscular patient requiring mechanical ventilation.

CONCLUSION

Ventilation of neuromuscular patients requires careful evaluation of the indications and rigorous follow up by a multidisciplinary team with wide experience of this type of disease.

Maladies neuromusculaires : évaluation des fonctions ventilatoires

Involvement of respiratory muscles is a nearly constant feature of neuromuscular disorders, leading to respiratory failure. A careful respiratory follow up adapted to the variable time course of each disease is therefore mandatory. As the first step, a systematic clinical evaluation is essential to detect the subtle respiratory symptoms and signs related to respiratory muscle failure. Dyspnea and orthopnea are often late findings in patients with a usually severe functional impairment due to peripheral muscle weakness. Nocturnal respiratory events (obstructive sleep apnea syndrome and hypoventilation) are strongly suggested by daytime hypersomnolence and frequent morning headaches. Physical evaluation is essential to detect accessory muscle recruitment, supine abdominal paradox, and encumbrance of upper or lower airways. Vital capacity (VC) is the most classical lung function test. The major limitation of spirometry is its poor sensitivity to detect a moderate inspiratory muscle weakness. Supine VC may improve the detection of diaphragmatic involvement. Peak expiratory flow during cough (cough PEF) gives an overall evaluation of cough efficiency, values below 160 to 270 L/min suggesting poor airway clearance. Arterial blood gases are performed in case of clinical signs, significant deterioration of lung function tests, or sleep desaturations. Hypercapnia is weakly related to lung function results in patients with Steinert dystrophy and those with bulbar involvement. A specific evaluation of respiratory muscle strength is mandatory, as these tests are both sensitive and highly prognostic. Possible discrepancies (particularly in bulbar patients) between maximal inspiratory pressure (PImax) and sniff nasal inspiratory pressure (SNIP) justify to perform both measurements and to select the highest pressure. A maximal expiratory pressure (PEmax) below 45 cm H2O may indicate a compromised cough efficiency but the correlation with cough PEF may be poor. A screening nocturnal oxymetry is useful to detect sleep apneas and hypoventilation. Criteria defining significant desaturations remain however controversial. Suspicion of obstructive sleep apnea syndrome on clinical grounds or oxymetry findings should be confirmed by a conventional polysomnography.

Forced vital capacity (FVC) as an indicator of survival and disease progression in an ALS clinic population

In a large cohort of 1034 patients with the diagnosis of definite or probable amyotrophic lateral sclerosis (ALS), the association of forced vital capacity (FVC) at baseline with (a) time to progression of 20 points in Appel ALS (AALS) score or (b) tracheostomy free survival was investigated. The median survival of ALS patients with baseline FVC <75% was 2.91 years, compared with 4.08 years for patients with baseline FVC >75% (p<0.001). Patients with baseline FVC <75% progressed more rapidly (taking 8.0 months to progress 20 AALS points) compared with patients with baseline FVC >75% (10.0 months, p<0.001). Moreover, FVC at first examination was identified as a significant predictor of survival and disease progression in both univariate and multivariate Cox regression models, after adjustment for age, sex, site of onset, diagnostic delay, riluzole therapy, and use of bilateral positive airway pressure and percutaneous endoscopic gastrostomy (p<0.001). We conclude that a single FVC value obtained at an initial visit may serve as a clinically meaningful predictor of survival and disease progression in ALS.

Sleep and Neuromuscular Disorders

Nocturnal sleep-related ventilatory alterations may occur in dis-proportion to the severity of the neuromuscular disorder. Diaphragm paralysis occurring with a neuromuscular disorder is an overlooked complication. Failure to thrive, daytime tiredness, and incapacitating fatigue may be the result of a correctable sleep-related abnormality, not the result of relentless progression of a neuromuscular condition. Polysomnographic evaluation is recommended for patients who have neuromuscular disorder who develop symptoms and signs of sleep-wake abnormality or nocturnal respiratory failure. Application of noninvasive positive airway ventilation and, in some cases, administration of supple-mental oxygen may improve quality of life and prolong survival of patients who have neuromuscular disorder.

Assessment of disease progression in motor neuron disease

Motor neuron disease (MND) is characterised by progressive deterioration of the corticospinal tract, brainstem, and anterior horn cells of the spinal cord. There is no pathognomonic test for the diagnosis of MND, and physicians rely on clinical criteria-upper and lower motor neuron signs-for diagnosis. The presentations, clinical phenotypes, and outcomes of MND are diverse and have not been combined into a marker of disease progression. No single algorithm combines the findings of functional assessments and rating scales, such as those that assess quality of life, with biological markers of disease activity and findings from imaging and neurophysiological assessments. Here, we critically appraise developments in each of these areas and discuss the potential of such measures to be included in the future assessment of disease progression in patients with MND.

Use of Sniff Nasal-Inspiratory Force to Predict Survival in Amyotrophic Lateral Sclerosis

Respiratory muscle weakness is the usual cause of death in amyotrophic lateral sclerosis. The prognostic value of the forced vital capacity (FVC), mouth-inspiratory force, and sniff nasal-inspiratory force were established in a group of 98 patients with amyotrophic lateral sclerosis who were followed trimonthly for 3 years. Sniff nasal-inspiratory force correlated with the transdiaphragmatic pressure (r = 0.9, p < 0.01). Sniff nasal-inspiratory force was most likely to be recorded at the last visit (96% of cases), compared with either the FVC or mouth-inspiratory force (86% and 81%, respectively, p < 0.01). A sniff nasal-inspiratory force less than 40 cm H(2)O was significantly related with nocturnal hypoxemia. When sniff nasal-inspiratory force was less than 40 cm H(2)O, the hazard ratio for death was 9.1 (p = 0.001), and the median survival was 6 +/- 0.3 months. The sensitivity of FVC < 50% for predicting 6-month mortality was 58% with a specificity of 96%, whereas sniff nasal-inspiratory force less than 40 H(2)O had a sensitivity of 97% and a specificity of 79% for death within 6 months. Thus the sniff nasal-inspiratory force test is a good measure of respiratory muscle strength in amyotrophic lateral sclerosis, it can be performed by patients with advanced disease, and it gives prognostic information.