Spirometry in amyotrophic lateral sclerosis

Força muscular respiratória e perfil postural e nutricional em crianças com doenças neuromusculares

INTRODUÇÃO: As doenças neuromusculares infantis são crônicas, degenerativas e determinam alterações funcionais, musculares e nutricionais. OBJETIVOS: Avaliar sistematicamente a força muscular respiratória e o perfil postural e nutricional de crianças com doenças neuromusculares em seguimento multidisciplinar institucional. MATERIAIS E MÉTODOS: Foram estudados pacientes com diferentes doenças neuromusculares por meio da verificação da força muscular respiratória, da avaliação nutricional de massa muscular, do índice de massa corpórea e da porcentagem (%) de gordura corporal, além de avaliação postural e dos padrões de movimento. RESULTADOS: Foram avaliados 41 sujeitos. As crianças do sexo masculino predominaram na população em estudo, sendo 82,9% dela (n = 34), e os outros 17,1% (n = 7) eram do sexo feminino. A média de idade encontrada foi de 9,65 ± 3,11 anos. O principal diagnóstico encontrado foi Distrofia Muscular de Duchenne, 43,9% (n = 18), seguido de Atrofia Muscular Espinhal, 9,75% (n = 4), Distrofia Congênita, 7,31% (n = 3), Distrofia Muscular de Cinturas, Polineuropatia e Miopatia Congênita, todos com 4,9% (n = 2), além de Distrofia Muscular Progressiva, Miastenia Grávis, Charcoot Marie Toot, Emery Dreifuss, encontrados em 2,43% (n = 1). Foi verificada uma diminuição da força muscular respiratória (PImáx = 81 ± 24,3 cmH2O, 91% predito e PEmáx = 70 ± 29,6 cmH2O, 72% predito), mais evidente nos músculos expiratórios. A Hiperlordose lombar foi encontrada em 26 pacientes (64%) e 9 pacientes (22%) já haviam perdido a capacidade de deambular. Em relação ao perfil nutricional, 90% dos pacientes (n = 30) mostraram uma alta incidência de perda de reserva muscular e 52% deles (n = 13) apresentaram a porcentagem de gordura corporal abaixo do aceitável. CONCLUSÃO: A avaliação multidisciplinar das doenças neuromusculares pediátricas podem auxiliar no estabelecimento de tratamento precoce da Fisioterapia para melhorar a qualidade de vida dos pacientes e cuidadores.

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.

Assessment of respiratory functions by spirometry and phrenic nerve studies in patients of amyotrophic lateral sclerosis

OBJECTIVE

Spirometry is the most common test recommended to monitor respiratory dysfunction in patients of amyotrophic lateral sclerosis (ALS). However, the test depends on the patient's efforts and may be difficult to conduct in patients with faciobulbar weakness. We aimed to study the role of phrenic nerve-electrophysiological studies to predict respiratory dysfunction and correlate it with the forced vital capacity (FVC) in patients of ALS.

METHODS

Forty-three unselected patients (32 male, 25 with limb-onset ALS, age 50±15 years) with clinically definite or probable ALS were included. They were evaluated at entry and after a period of 6 months with the ALS functional rating scale (ALSFRS), their respiratory subscores (ALS-FRSr), their FVC values as determined by spirometry, and phrenic nerve studies.

RESULTS

Six patients could not perform a satisfactory spirometry at the onset and during the course of illness. All the six patients had severe faciobulbar weakness. Respiratory abnormalities on spirometry were found in 85% of patients, whereas only 30% were symptomatic for respiratory dysfunction. In patients with severe respiratory dysfunction (FVC<60%), the phrenic nerve motor amplitudes (PNAMPs) were significantly reduced compared to those with mild-to-moderate respiratory dysfunction (FVC≥60%). The FVC value showed a significant correlation with the PN-AMP. Nine patients had a poor outcome (death or severe disability) at the end of a period of 6 months. Low levels of both FVC and PN-AMP were predictors of poor outcome for patients at the end of 6 months.

CONCLUSION

We conclude that respiratory dysfunction, as determined by spirometry, is common in patients of ALS. However, only about one-third of patients show symptoms of respiratory distress. Clinical symptoms of respiratory distress are unreliable predictors of respiratory failure in ALS. Measurement of PN-AMP at the time of presentation may be an additional tool to assess respiratory dysfunction in ALS. Reduced PN-AMP values may be indicative of low FVC and may have some role in the assessment of respiratory function in patients in whom a routine spirometry is not possible due to limitations arising from the illness. Both low FVC and reduced PN-AMP at the time of presentation are predictors of poor outcome for patients at the end of 6 months.

Management of respiratory symptoms in ALS

Respiratory insufficiency is a frequent feature of ALS and is present in almost all cases at some stage of the illness. It is the commonest cause of death in ALS. FVC is used as important endpoint in many clinical trials, and in decision-making events for patients with ALS, although there are limitations to its predictive utility. There are multiple causes of respiratory muscle failure, all of which act to produce a progressive decline in pulmonary function. Diaphragmatic fatigue and weakness, coupled with respiratory muscle weakness, lead to reduced lung compliance and atelectasis. Increased secretions increase the risk of aspiration pneumonia, which further compromises respiratory function. Bulbar dysfunction can lead to nutritional deficiency, which in turn increases the fatigue of respiratory muscles. Early recognition of respiratory decline and symptomatic intervention, including non-invasive ventilation can significantly enhance both quality of life and life expectancy in ALS. Patients with respiratory failure should be advised to consider an advance directive to avoid emergency mechanical ventilation.

Hypoventilation syndromes

A wide variety of mechanisms can lead to the hypoventilation associated with various medical disorders, including derangements in central ventilatory control, mechanical impediments to breathing, and abnormalities in gas exchange leading to increased dead space ventilation. The pathogenesis of hypercapnia in obesity hypoventilation syndrome remains somewhat obscure, although in many patients comorbid obstructive sleep apnea appears to play an important role. Hypoventilation in neurologic or neuromuscular disorders is primarily explained by weakness of respiratory muscles, although some central nervous system diseases may affect control of breathing. In other chest wall disorders, obstructive airways disease, and cystic fibrosis, much of the pathogenesis is explained by mechanical impediments to breathing, but an element of increased dead space ventilation also often occurs. Central alveolar hypoventilation syndrome involves a genetically determined defect in central respiratory control. Treatment in all of these disorders involves coordinated management of the primary disorder (when possible) and, increasingly, the use of noninvasive positive pressure ventilation.

Pulmonary function tests and diaphragmatic compound muscle action potential in patients with sporadic amyotrophic lateral sclerosis

BACKGROUND

Respiratory failure is the primary cause of death in patients with amyotrophic lateral sclerosis (ALS). Diaphragmatic compound muscle action potentials (DCMAP) are valid parameters to assess the respiratory muscle innervation.

AIM

In this study we propose to establish evidence of pulmonary dysfunction in patients with ALS and its relation to DCMAP parameters among patients with sporadic ALS.

MATERIALS AND METHODS

Twenty nine patients (M-20, F-9) diagnosed to have sporadic ALS by El. Escorial criteria, without symptoms of pulmonary dysfunction, and able to perform the PFT satisfactorily, were studied. Thirty controls (M-20, F-10) were selected from patient's relatives. Forced vital capacity (FVC), forced expiratory volume in one second (FEV(1)), peak expiratory flow rate (PEFR) and maximum voluntary ventilation (MVV) were measured by spirometry. Maximum expiratory pressure (MEP) was measured by digital peak pressure monitor. Right phrenic nerve conductions (DCMAP) were performed and the latencies and amplitude of diaphragmatic com-pound action potential (DCMAP) was recorded in controls and ALS patients.

RESULTS

The mean age of patients was 51.41 +/- 10.72 years (37-82) and control was 53.57 +/- 8.85 years (30-68). None of the patients had symptoms or clinical evidence of respiratory dysfunction. The FVC, FEV1, PEFR, MVV, MIP and MEP were significantly (P < 0.001) reduced in ALS. The mean DCMAP amplitude was reduced among patients (610 +/- 506.231 muv) as compared to controls (1303.33 +/- 584.56, P < 0.001) and mean latency was increased in patients (9.73 +/- 2.57 ms) compared to controls (7.69 +/- 0.87, P = 0.001). There was significant negative correlation between PFTs and latencies of DCMAP. Amplitude of DCMAP did not correlate with PFTs.

CONCLUSION

There is significant negative correlation between DCMAP latencies and PFTs suggesting early loss of myelinated fibres and diaphragmatic dysfunction. DCMAP latencies may be a good indicator of early respiratory muscle involvement and also of disease progression in ALS.

Spirometer‐dependence of vital capacity in ALS: Validation of a portable device in 52 patients

Since the evaluation of vital capacity (VC) needs to be carried out every three months in patients with amyotrophic lateral sclerosis (ALS), a portable spirometer would be of value in clinical practice. Over the follow-up of 52 ALS patients, we compared the values of slow vital capacity measured by two spirometers: a reference flow-metered spirometer based on a Hans-Rudolph pneumotachograph and a portable Venturi spirometer. The objectives were to analyse the overall concordance of the measurements from the two devices and determine a discordance cut-off. The correlation between measurements was high (r = 0.936) and significant (p<10(-20)). Bland and Altman analysis showed that the measurements were concordant at a statistical risk of 5%; nevertheless, on examination of the raw differences between the measurements, two sub-populations could be identified on either side of the 56% cut-off where the means of the differences were significantly different (p<0.0001). The 56% cut-off was also statistically significant in plotting differences against the coefficient of variations of the data pairs expressed as (100 x s/mean). The differences observed between the two spirometers could be explained by technical differences between the devices as well as by an increase in variability with progression of the disease. In conclusion, this study demonstrates that a portable spirometer can be used reliably at the bedside. For values of vital capacity below the discordance cut-off of 56%, vital capacity should be determined by operators trained in pulmonary function examinations.

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.

Palliative care in amyotrophic lateral sclerosis, Parkinson's disease, and multiple sclerosis

BACKGROUND

Amyotrophic lateral sclerosis, Parkinson's disease, atypical parkinsonian syndromes, and multiple sclerosis are progressive neurologic disorders that cumulatively afflict a large number of people. Effective end-of-life palliative care depends upon an understanding of the clinical aspects of each of these disorders.

OBJECTIVES

The authors review the unique and overlapping aspects of each of these disorders with an emphasis upon the clinical management of symptoms.

DESIGN

The authors review current management and the supporting literature.

CONCLUSIONS

Clinicians have many effective therapeutic options to choose from when managing the symptoms produced by these disorders.

A clinical pilot study: high frequency chest wall oscillation airway clearance in patients with amyotrophic lateral sclerosis

Respiratory complications are common in patients with amyotrophic lateral sclerosis (ALS) with respiratory failure representing the most common cause of death. Ineffective airway clearance resultant from deficient cough frequently contributes to these abnormalities. We sought to evaluate the effectiveness of high frequency chest wall oscillation (HFCWO) administered through the Vest Airway Clearance System when added to standard care in preventing pulmonary complications and prolonging the time to death in patients with ALS. This is a single center study performed at the Penn State Milton S. Hershey Medical Center (HMC). Nine patients with a diagnosis of ALS and concurrently receiving non-invasive ventilatory support with bi-level positive airway pressure (BiPAP) were recruited from the outpatient clinic at HMC. Four patients were randomized to receive standard care and five patients to receive standard care plus the addition of HFCWO administered twice-daily for 15 min duration. Longitudinal assessments of oxyhemoglobin saturation, forced vital capacity (FVC), and adverse events were obtained until time of death. Pulmonary complications of atelectasis, pneumonia, hospitalization for a respiratory-related abnormality, and tracheostomy with mechanical ventilation were monitored throughout the study duration. No differences were observed between treatment groups in relation to the rate of decline in FVC. The addition of HFCWO airway clearance failed to improve time to death compared to standard treatment alone (340 days +/- 247 vs. 470 days +/- 241; p = 0.26). The random allocation of HFCWO airway clearance to patients with ALS concomitantly receiving BiPAP failed to attain any significant clinical benefits in relation to either loss of lung function or mortality. This study does not exclude the potential benefit of HFCWO in select patients with ALS who have coexistent pulmonary diseases, pre-existent mucus-related pulmonary complications, or less severe levels of respiratory muscle weakness.

Development of chronic hypoventilation in amyotrophic lateral sclerosis patients

Early prediction of respiratory muscle involvement and chronic hypoventilation (CH) in amyotrophic lateral sclerosis (ALS) patients can help to plan mechanical ventilatory aids and palliative care interventions well before respiratory failure occurs. To describe the natural history of the progressive pulmonary dysfunction leading to CH, and to identify potential parameters associated with its development in ALS, we prospectively followed 38 ALS patients up to 26 months, starting from their first presentation at our Clinic. At study entry, median FVC was 87% (interquartile range: 72-104%) and declined by 10% after 6 months (range: 2-49%), showing a very high inter-patient variability. Over the 26-months follow-up, 19 patients (50%) presented CH in the first 12 months, and eight patients (21%) developed CH in the remaining 14 months of the study. The remaining 29% of patients did not show signs of CH during the whole period of observation. In the Cox model, the category of disease progression (rapid vs. intermediate and slow), assessed using the Appel ALS Rating Scale (AARS) in the first 3 months after presentation, was the only variable associated with a significantly increased likelihood of CH. We conclude that CH can occur within 1 year from presentation in a great proportion of patients, independently from their initial respiratory status. Including the patients in specific categories of early disease progression, as assessed with the AARS, could be a sensitive method to identify patients with different risk of developing CH, and may help physicians to more efficiently plan the frequencies of respiratory evaluations, initiate mechanical ventilation and discuss advance directives with the patients and their caregivers.

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.

Effects of non-invasive ventilation on survival and quality of life in patients with amyotrophic lateral sclerosis: a randomised controlled trial

BACKGROUND

Few patients with amyotrophic lateral sclerosis currently receive non-invasive ventilation (NIV), reflecting clinical uncertainty about the role of this intervention. We aimed to assess the effect of NIV on quality of life and survival in amyotrophic lateral sclerosis in a randomised controlled trial.

METHODS

92 of 102 eligible patients participated. They were assessed every 2 months and randomly assigned to NIV (n=22) or standard care (n=19) when they developed either orthopnoea with maximum inspiratory pressure less than 60% of that predicted or symptomatic hypercapnia. Primary validated quality-of-life outcome measures were the short form 36 mental component summary (MCS) and the sleep apnoea quality-of-life index symptoms domain (sym). Both time maintained above 75% of baseline (T(i)MCS and T(i)sym) and mean improvement (microMCS and microsym) were measured.

FINDINGS

NIV improved T(i)MCS, T(i)sym, microMCS, microsym, and survival in all patients and in the subgroup with better bulbar function (n=20). This subgroup showed improvement in several measures of quality of life and a median survival benefit of 205 days (p=0.006) with maintained quality of life for most of this period. NIV improved some quality-of-life indices in those with poor bulbar function, including microsym (p=0.018), but conferred no survival benefit.

INTERPRETATION

In patients with amyotrophic lateral sclerosis without severe bulbar dysfunction, NIV improves survival with maintenance of, and improvement in, quality of life. The survival benefit from NIV in this group is much greater than that from currently available neuroprotective therapy. In patients with severe bulbar impairment, NIV improves sleep-related symptoms, but is unlikely to confer a large survival advantage.

The cost-effectiveness of early noninvasive ventilation for ALS patients

Background

Optimal timing of noninvasive positive pressure ventilation (NIPPV) initiation in patients with amyotrophic lateral sclerosis (ALS) is unknown, but NIPPV appears to benefit ALS patients who are symptomatic from pulmonary insufficiency. This has prompted research proposals of earlier NIPPV initiation in the ALS disease course in an attempt to further improve ALS patient quality of life and perhaps survival. We therefore used a cost-utility analysis to determine a priori what magnitude of health-related quality of life (HRQL) improvement early NIPPV initiation would need to achieve to be cost-effective in a future clinical trial.

Methods

Using a Markov decision analytic model we calculated the benefit in health-state utility that NIPPV initiated at ALS diagnosis must achieve to be cost-effective. The primary outcome was the percent utility gained through NIPPV in relation to two common willingness-to-pay thresholds: $50,000 and $100,000 per quality-adjusted life year (QALY).

Results

Our results indicate that if NIPPV begun at the time of diagnosis improves ALS patient HRQL as little as 13.5%, it would be a cost-effective treatment. Tolerance of NIPPV (assuming a 20% improvement in HRQL) would only need to exceed 18% in our model for treatment to remain cost-effective using a conservative willingness-to-pay threshold of $50,000 per QALY.

Conclusion

If early use of NIPPV in ALS patients is shown to improve HRQL in future studies, it is likely to be a cost-effective treatment. Clinical trials of NIPPV begun at the time of ALS diagnosis are therefore warranted from a cost-effectiveness standpoint.

Survival in Amyotrophic Lateral Sclerosis With Home Mechanical Ventilation

STUDY OBJECTIVES

To analyze (1) the impact of a protocol of early respiratory evaluation of the indications for home mechanical ventilation (HMV) in patients with amyotrophic lateral sclerosis (ALS), and (2) the effects of the protocol and of bulbar involvement on the survival of patients receiving noninvasive ventilation (NIV).

DESIGN AND SETTING

Retrospective study in a tertiary care referral center.

PATIENTS

HMV was indicated in 86 patients with ALS, with 22 patients (25%) presenting with intolerance to treatment associated with bulbar involvement. Treatment with HMV had been initiated in 15 of 64 patients prior to initiating the protocol (group A) and in the remaining 49 patients after protocol initiation (group B).

RESULTS

In group A, the majority of patients began treatment with HMV during an acute episode requiring ICU admission (p = 0.001) and tracheal ventilation (p = 0.025), with a lower percentage of patients beginning HMV treatment without respiratory insufficiency (p = 0.013). No significant differences in survival rates were found between groups A and B among patients treated with NIV. Greater survival was observed in group B (p = 0.03) when patients with bulbar involvement were excluded (96%). Patients without bulbar involvement at the start of therapy with NIV presented a significantly better survival rate (p = 0.03). Multivariate analysis showed bulbar involvement to be an independent prognostic factor for survival (relative risk, 1.6; 95% confidence interval, 1.01 to 2.54; p = 0.04). No significant differences in survival were observed between patients with bulbar involvement following treatment with NIV and those with intolerance, except for the subgroup of patients who began NIV treatment with hypercapnia (p = 0.0002).

CONCLUSIONS

Early systematic respiratory evaluation in patients with ALS is necessary to improve the results of HMV. Further studies are required to confirm the benefits of NIV treatment in patients with bulbar involvement, especially in the early stages.

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.

Surveillance et traitement des troubles respiratoires associés à la sclérose latérale amyotrophique

INTRODUCTION

In amyotrophic lateral sclerosis (ALS), respiratory muscle involvement is highly predictive of survival and quality of life (QOL). There is compelling evidence that non invasive ventilation (NIV) prolongs survival by several months and improves QOL more than any other currently available treatment. Frequent testing of pulmonary function and regular evaluations are recommended since 1999 by the American Academy of Neurology in order to take appropriate treatment decisions.

STATE OF ART

There are numerous tests available to evaluate respiratory status in ALS and it is important to know their sensitivity and specificity to recognize clinical risk situations. Some recent data suggest that sniff nasal pressure and maximal inspiratory pressure (MIP) can be performed reliably by most ALS patients and are more sensitive to decrements in inspiratory muscle strength than spirometry or arterial blood gasometry.

PERSPECTIVES

Airway obstruction caused by ineffective coughing is the principal cause of intolerance to NIV. Several factors other than respiratory muscle strength may affect pulmonary function: postural changes, nutritional status, infectious disease, drugs.

CONCLUSION

The neurologist has to coordinate multidisciplinary care, with attention to individual patient preferences, and with a frank and compassionate discussion between the patient, the family, the physicians and the caregivers.

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.

Predictors of noninvasive ventilation tolerance in patients with amyotrophic lateral sclerosis

Noninvasive ventilation (NIV) appears to improve survival and quality of life in patients with amyotrophic lateral sclerosis (ALS), but little is known about predictors of NIV tolerance. NIV use was assessed and clinical predictors of tolerance were investigated, using predictive modeling, in ALS patients diagnosed and followed in our clinic until death over a 4-year time period. Patients were prescribed NIV based on current practice parameters when respiratory symptoms were present or forced vital capacity was less than 50%. We prescribed NIV in 52% (72) of patients. For those prescribed NIV, information regarding tolerance was available for 50 patients, with 72% (36) tolerant to its use. Tolerance was six times more likely in limb-onset than bulbar-onset ALS patients, with a trend toward reduced tolerance in those with lower forced vital capacity at NIV initiation. Age, gender, and duration of disease were not predictors of NIV tolerance. We conclude that a majority of ALS patients who are prescribed NIV can successfully become tolerant to its use.

[Review of nutritional and respiratory support in ALS]

During the evolution of amyotrophic lateral sclerosis (ALS), quality of life and survival of patients are related to respiratory and nutritional status. After diagnosis, a multidisciplinary care has to be promptly organized and coordinated by the referring neurologist. The nutritional and respiratory support imply that neurologists know their specific means of evaluation with their sensitivity and sensibility and be able to recognize clinical risk situations. The informations of patients on assisted-ventilation and nutritional support by using gastrostomy may be done early, precisely and trustfully. Well informed patient's choices must be respected. Nutritional and respiratory supports may be based on recommendations established by the American Academy of Neurology. This review will present and discuss their main aspects in patients with ALS.

Patterns of mortality in patients with motor neurone disease

OBJECTIVE

Motor neurone disease (MND) is a rapidly fatal condition with survival of less than 4 years. Patients can deteriorate quickly in the preterminal stages resulting in inappropriate resuscitation or admission to intensive care units (ICU) or accident and emergency (A & E).

MATERIAL AND METHODS

We looked at patterns of mortality with emphasis on the place of death. A retrospective study was performed of all patients attending an MND clinic, who had died within a 10-year period.

RESULTS

Of 179 patients (63 female), 81 patients (45%) died at home, in a hospice or in a nursing home. Sixty-five patients (36%) died in hospital (11 in ICU or A & E). Nine of the latter were previously known to have MND and six admissions were probably avoidable. Most ward patients died of respiratory causes and were treated conservatively.

CONCLUSION

The proportion of patients dying in A & E or ICU was small but could have been reduced further. A number of those who died on the wards could probably have been managed conservatively at home. Older patients and those with bulbar disease had a poorer prognosis.

Outcome of ventilatory support for acute respiratory failure in motor neurone disease

OBJECTIVES

To review the outcome of acute ventilatory support in patients presenting acutely with respiratory failure, either with an established diagnosis of motor neurone disease (MND) or with a clinical event where the diagnosis of MND has not yet been established.

METHODS

Outcome was reviewed in 24 patients with respiratory failure due to MND who received endotracheal intubation and intermittent positive pressure ventilation either at presentation or as a result of the unexpected development of respiratory failure. Patients presenting to local hospitals with acute respiratory insufficiency and requiring tracheal intubation, ventilatory support, and admission to an intensive therapy unit (ITU) before transfer to a regional respiratory care unit were selected. Clinical features of presentation, management, and outcome were studied.

RESULTS

24 patients with MND were identified, all being intubated and ventilated acutely within hours of presentation. 17 patients (71%) were admitted in respiratory failure before the diagnosis of MND had been made; the remaining seven patients (29%) were already known to have MND but deteriorated rapidly such that intubation and ventilation were initiated acutely. Seven patients (29%) died on ITU (between seven and 54 days after admission). 17 patients (71%) were discharged from ITU. 16 patients (67%) received long term respiratory support and one patient required no respiratory support following tracheal extubation. The daily duration of support that was required increased gradually with time.

CONCLUSION

When a patient with MND is ventilated acutely, with or without an established diagnosis, independence from the ventilator is rarely achieved. Almost all of these patients need long term ventilatory support and the degree of respiratory support increases with time as the disease progresses. The aim of management should be weaning the patient to the minimum support compatible with symptomatic relief and comfort. Respiratory failure should be anticipated in patients with MND when the diagnosis has been established.

Spirometry in the supine position improves the detection of diaphragmatic weakness in patients with amyotrophic lateral sclerosis

STUDY OBJECTIVES

To determine which respiratory function tests best predicted diaphragmatic strength in patients with amyotrophic lateral sclerosis.

PATIENTS AND METHODS

Patients referred for pulmonary evaluation were included (n = 25) if they underwent measurement of transdiaphragmatic pressure (Pdi) and one or more of the following on the same day: upright FVC, supine FVC, upright FEV(1), supine FEV(1), maximal inspiratory pressure (MIP), maximal expiratory pressure (MEP), and PaCO(2). Abdominal paradox and use of accessory muscles were also assessed. Bivariate analyses were performed using simple linear regression. Sensitivity and specificity of the potential predictors to detect an abnormal Pdi (< 70 cm H(2)O) were calculated.

SETTING

Pulmonary function laboratory of an academic medical center.

RESULTS

Upright FVC, FEV(1), and MEP were all significantly correlated with Pdi, while MIP and PaCO(2) were not. Supine FVC was the most highly correlated predictor of Pdi (R(2) = 0.76). A cutoff of supine FVC that was < 75% predicted was 100% sensitive and specific for predicting an abnormally low Pdi. Accessory muscle use and abdominal paradox were both significantly associated with Pdi, and the presence of accessory muscle use had a sensitivity of 84% and a specificity of 100% for detecting a low Pdi.

CONCLUSIONS

Our findings suggest that supine FVC is an excellent and simple test of diaphragmatic weakness.

Cost effectiveness of treatments for amyotrophic lateral sclerosis: a review of the literature

Amyotrophic lateral sclerosis (ALS) is a difficult to diagnose, fatal, progressive degenerative disease with an average survival time of 2 to 5 years. Percutaneous endoscopic gastrotomy (PEG) and bi-level intermittent positive pressure (BIPAP) ventilation may be the major interventions leading to longer survival of patients with ALS. Riluzole has been shown to have modest effects on survival (as opposed to functional) gains and is currently the only drug approved for the treatment of ALS. There is conflicting evidence with regard to the ability of recombinant human insulin-like growth factor (rhIGF-I) to retard ALS progression. Mechanical ventilation (via a tracheostomy tube) is expensive, but is widely used in later stage patients with ALS in the US. A review of nine cost-effectiveness studies of riluzole and one of rhIGF-I found the following: drug costs and survival gains are the major drivers of cost effectiveness; survival gains are estimated from truncated databases with a high degree of uncertainty; more accurate stage-specific utility weights based on patients who agreed to treatment are needed; case incidence-based evaluations should be carried out; cost-effectiveness ratios are insensitive to discount rates; employment and caregiver issues or externalities have been widely ignored; threshold acceptance cost-effectiveness values are ill-defined and evaluations are not generalisable to other countries because of cost and treatment style differences. On account of the high degree of uncertainty pertaining to survival gains and the relatively high costs per life years or quality-adjusted life-years gained, and while acknowledging that not every therapy has to be cost effective (e.g. orphan drugs), it is still inconclusive as to whether or not riluzole or rhIGF-1 can be considered as cost-effective therapies for ALS.

Pulmonary function testing in neuromuscular disease

Pulmonary function testing is useful in the diagnosis and management of patients with neuromuscular disease. It is important, however, to keep in mind that certain tests commonly used to assess these patients, such as MIPs and MEPs, although useful, are fraught with potential error and rigorous attention should be paid to technical details when performing them. In addition, many studies have shown that pulmonary impairment does not always parallel generalized muscle impairment and thorough testing therefore should be done in any patient with neuromuscular disease to assess the level of respiratory compromise accurately. In addition, the clinician should be aware that the pattern of involvement-bulbar versus inspiratory, versus expiratory muscle weakness-may vary markedly among patients, even with the same diagnosis, so testing should be tailored to detect these patterns. Furthermore, serial follow-up examinations should be performed to track the rate of deterioration so that therapeutic interventions can be initiated before respiratory crises occur.

Respiratory Failure or Impairment in Amyotrophic Lateral Sclerosis

Respiratory complications account for the majority of deaths occurring in patients suffering from amyotrophic lateral sclerosis (ALS). Patients normally succumb to their illness within an average of 3 to 5 years from the time of diagnosis from complications such as hypoventilation, hypoxemia, hypercarbia, aspiration, and other pneumonia and pulmonary emboli. Although invariably disabling, ALS need not be fatal if respiratory involvement is detected early, which will allow sufficient time to discuss and implement treatment options. The recently published American Academy of Neurology guidelines for the management of ALS recommends the following: Serial measures of pulmonary function to guide management and determine prognosis. Noninvasive ventilatory support--an effective initial therapy for symptomatic chronic hypoventilation and prolonged survival. Invasive ventilatory support when long-term survival is the goal and noninvasive support is no longer sufficient. Physicians respect the right of the patient to choose, refuse, or withdraw ventilatory support. Liberal use of opiates and anxiolytics to relieve dyspnea and anxiety when ventilatory support is refused or withdrawn.

Development of a patient-specific dyspnoea questionnaire in motor neurone disease (MND): the MND dyspnoea rating scale (MDRS)

Motor neurone disease (MND) is a progressive, unremitting and fatal disease. Respiratory dysfunction is common and a significant cause of morbidity. The relationship between subjective dyspnoea and objective measures of lung function have been unexplored in MND. Increasing interest in the specific treatment of respiratory symptoms in MND has highlighted the need for simple, reliable and valid measures to quantify the degree of dyspnoea in this condition. Several generic questionnaires have been developed to rate subjective breathlessness but are inappropriate for use in MND patients as they often assess dyspnoea by exercise-limitation. As yet, there are no published disease-specific measures to assess dyspnoea in MND. In order to accurately and reproducibly measure the subjective experience of dyspnoea in this patient group, we have developed and validated a novel patient-specific dyspnoea questionnaire, the MND dyspnoea rating scale (MDRS). It comprises three domains covering dyspnoea, emotion and mastery and is valid for use in MND patients at all stages of disease progression. In our cohort of 40 unselected patients with MND we have shown that the patients subjective experience of dyspnoea is closely related to emotion and psychological control over the disease. Dyspnoea is not related to objective measures of lung function such as vital capacity, irrespective of limb or bulbar presentation. In conclusion, vital capacity, although useful prognostically, is only one aspect of respiratory function in MND. The MDRS is a reliable and valid tool to rate subjective dyspnoea in MND.

Sleep disorders and diaphragmatic function in patients with amyotrophic lateral sclerosis

In amyotrophic lateral sclerosis (ALS), the progressive loss of upper and lower motor neurons leads to respiratory failure, often with predominant diaphragm dysfunction, and death. Because the diaphragm is the only active inspiratory muscle during rapid eye movement (REM) sleep, there is a high theoretical risk of respiratory disorders during REM sleep in patients with ALS. To assess this hypothesis, we studied sleep characteristics (polysomnography) in 21 patients with ALS, stratified according to the presence or absence of diaphragmatic dysfunction. Diaphragmatic dysfunction was defined as an absent or delayed diaphragm response to cervical or cortical magnetic stimulation, abdominal paradox, or respiratory pulse (Group 1, 13 patients). These patients did not differ in age, clinical course, or form (bulbar or spinal) from the eight others, who did not have diaphragmatic dysfunction (Group 2). REM sleep was reduced in Group 1 (7 +/- 7% of total sleep time; mean +/- SD) and normal in Group 2 (18 +/- 6%, p = 0.004). Apneas or hypopneas were rare in both groups. In Group 1, REM sleep was absent or minimal (less than 3 min) in five patients. An unusual and remarkable preservation of phasic inspiratory sternomastoid activation during REM was associated with longer REM sleep duration in six of the other patients with diaphragmatic dysfunction. Median survival time was dramatically shorter (217 d) in Group 1 than in Group 2 (619 d, p = 0.015).

Pulmonary evaluation and prevalence of non-invasive ventilation in patients with amyotrophic lateral sclerosis: a multicenter survey and proposal of a pulmonary protocol

In order to evaluate the current standard of care for the management of respiratory failure in patients with amyotrophic lateral sclerosis (ALS), a questionaire was mailed to the Medical Directors of 48 multidisciplinary ALS centers in the United States. Twenty centers reported information on 2357 patients, mean of 124 patients per center. Pulmonary function tests were performed at each visit in 17/20 institutions. Arterial blood gases, maximal expiratory pressures and maximal inspiratory pressures were followed in three centers and serum chloride was monitored in only four centers. The use of non-invasive ventilation (NIV) was extremely variable (range 0-50%) and included 360 patients (15%). The majority of centers used symptoms/signs of hypoventilation and worsening forced vital capacity (FVC) to initiate NIV with no established protocol. A FVC between 20 and 40% was used by most centers to initiate NIV. Due to great variability in the approach to monitoring pulmonary function among ALS centers and the modest effects of current medications to slow disease progression, we propose the use of a structured protocol which can prospectively study the role of NIV in prolonging survival and improving quality of life.