Respiratory assistance with a non-invasive ventilator (Bipap) in MND/ALS patients: survival rates in a controlled trial

Nocturnal mechanical ventilation for chronic hypoventilation in patients with neuromuscular and chest wall disorders

BACKGROUND

Chronic alveolar hypoventilation is a common complication of many neuromuscular and chest wall disorders. Long term nocturnal mechanical ventilation is used to treat an increasing number of patients.

OBJECTIVES

To examine the efficacy of nocturnal mechanical ventilation in relieving hypoventilation related symptoms in patients with neuromuscular or chest wall disorders.

SEARCH STRATEGY

Search of the Cochrane Neuromuscular Disease Group register for randomized trials and enquiry from authors of trials and other experts in the field.

SELECTION CRITERIA

Types of studies: quasi-randomized or randomized controlled trials

TYPES OF PARTICIPANTS

patients with neuromuscular or chest wall disorder-related stable chronic hypoventilation of all ages and all degrees of severity. Types of interventions: any type and any mode of nocturnal mechanical ventilation. Types of outcome measures: Primary: short term and long term reversal of hypoventilation related clinical symptoms Secondary: unplanned hospital admission rate, one year mortality, short term and long term reversal of day time hypercapnia, improvement of lung function and improvement of sleep breathing disorders.

DATA COLLECTION AND ANALYSIS

We identified four randomized trials. One author extracted the data and another checked them. Individual data were available from the authors of the largest study.

MAIN RESULTS

The four eligible trials included a total of 51 patients. The risk difference (proportion of patients) of no improvement of hypoventilation related clinical symptoms in the short term following nocturnal mechanical ventilation was significant and favoured treatment, -0.417 (95% CI -0.639 to -0.194). However, there was significant heterogeneity across the studies (p<0.001). Similarly, the risk difference of no reversal of day time hypercapnia in the short term following nocturnal ventilation was significant and favoured treatment, -0.635 (95% CI -0.874 to -0.396). The weighted mean difference of nocturnal mean oxygen saturation percent was 5.5 (95% CI 1.5 to 9.4) more improvement in patients treated with nocturnal mechanical ventilation. For the primary and most of the secondary outcome measures there was no significant difference between nocturnal mechanical ventilation and no ventilation in the long term, except for one-year mortality. Indeed, the risk difference of death one year following implementation of nocturnal mechanical ventilation was significant and favoured treatment, -0.259 (95% CI -0.478 to -0. 041). However, there was significant heterogeneity across the studies (p<0.001). Most of the secondary outcomes were not assessed in the eligible trials. No data could be summarised for the comparisons between invasive and non-invasive mechanical ventilation, between intermittent positive pressure and negative pressure ventilation, and between volume-cycled and pressure-cycled ventilation.

REVIEWER'S CONCLUSIONS

Current evidence about the therapeutic benefit of mechanical ventilation is weak, but consistent, suggesting alleviation of the symptoms of chronic hypoventilation in the short term, and in two small studies survival was prolonged. Mechanical ventilation should be offered as a therapeutic option to patients with chronic hypoventilation due to neuromuscular diseases. Further larger randomized trials are needed to confirm long term beneficial effects of nocturnal mechanical ventilation on quality of life, morbidity and mortality, to assess its cost-benefit ratio, and to compare the different types and modes of ventilation.

Amyotrophic Lateral Sclerosis

More than a century after its initial clinicopathologic description, amyotrophic lateral sclerosis (ALS) remains a largely fatal, progressive neurodegenerative disorder for which few efficacious pharmacotherapies with an impact directly on the natural course of the illness exist. The only currently approved therapy, the antiglutamatergic agent riluzole, has been shown to have only a marginal survival benefit in the absence of changes in functional assessments during the disease course. The efficacy of recombinant human insulin-like growth factor (rhIGF-1) remains controversial. In light of this, the primary focus of treatment for individuals with ALS remains symptomatic, through a multidisciplinary team approach including physicians, nurses, speech/language pathologists, physical therapists, occupational therapists, dietitians, social workers, and respiratory therapists.

Neuromuscular disease and hypoventilation

Alveolar hypoventilation associated with neuromuscular disease can occur in acute and chronic forms. In the acute form, progressive weakness of respiratory muscles leads to rapid reduction in vital capacity followed by respiratory failure with hypoxemia and hypercarbia. Symptoms are those of acute respiratory failure, including dyspnea, tachypnea, and tachycardia. In the chronic form, impairment of the respiratory muscles affects mechanical properties of the lungs and chest wall, decreases the ability to clear secretions, and eventually may alter the function of the central respiratory centers. Symptoms include orthopnea, fatigue, disturbed sleep, and hypersomnolence. Treatment and outcome of the disease's chronic form are dependent on the underlying clinical cause of the alveolar hypoventilation. For chronic but stable diseases such as old polio, quadriplegia, or kyposcoliosis, mechanical support of minute ventilation can reverse symptoms. For chronic and progressive disease such as muscular dystrophy and amyotrophic lateral sclerosis, mechanical support of minute ventilation provides only symptomatic relief and is usually associated with deterioration to the point of complete ventilator dependency for survival. For the chronic progressive forms of alveolar hypoventilation, there is currently a need for quality randomized controlled clinical trials to define physiologic indicators and appropriate timing for mechanical support of minute ventilation.

Can amyotrophic lateral sclerosis patients with respiratory insufficiency exercise?

The authors have shown in a recent paper that survival with amyotrophic lateral sclerosis (ALS) can be increased by the use of non-invasive methods of assisted ventilation (Bipap). However, the progression of muscle weakness was not affected and the quality of life was not positively enhanced. In ALS, reduced physical activity may partially be secondary to alveolar hypoventilation syndrome. This leads to deconditioning of ALS/motor neuron disease (ALS/MND) patients. The authors decided to investigate the possibility of reducing motor decline by exercising these patients to the anaerobic threshold, but simultaneously compensating the respiratory insufficiency with the Bipap STD. We conducted a controlled single blind study, exercising eight consecutive ALS/MND patients and used a control group of 12 ALS/MND patients. The patients were all evaluated during a 1 year period. Respiratory function tests (RFT) were performed at entry and then at 6 month intervals. Barthel, Functional Independent Mobility scale (FIM) and Spinal and Bulbar Norris scores were recorded every 3 months. There was a significant difference between the two groups with respect to FIM scores (P<0.03), but not Barthel scores (P<0.8). A slower clinical course (Spinal Norris score P<0.02) and a significant difference in the slope of the RFT (P<0.008) were observed in the treated group, suggesting that exercise may be beneficial in ALS patients once Bipap is used to control peripheral and muscle oxygenation.

Reflex sympathetic dystrophy associated with amyotrophic lateral sclerosis

Reflex sympathetic dystrophy (RSD) is a syndrome characterised by severe distal pain and vasomotor changes. It is believed to be caused by sympathetic nervous system overactivity. Trauma is the most frequent precipitant event. An association with amyotrophic lateral sclerosis (ALS) has been reported only once. We report three patients with ALS in whom the occurrence of RSD, in one of them at a very early clinical stage, seemed to have precipitated a more rapid clinical evolution. New sprouting re-innervating fibres have abnormal ion channels which might increase the risk of RSD. On the other hand, motor changes have been described in RSD, as well as motor strength improvement after RSD treatment. The complex relation of ALS with RSD is discussed. In all ALS patients pain followed by further loss of function should prompt a search for RSD.

Respiratory disorders in ALS: sleep and exercise studies

Sleep disruption in ALS/MND is related to hypoventilation and nocturnal O(2) saturation. Maximal inspiratory pressure (PI(max)) proved sensitive in predicting nocturnal O(2) saturation. However, PI(max) is highly dependent on patient collaboration; on the other hand Mouth Occlusion Pressure (MOP) is a reliable, non-volitional parameter index of central respiratory drive. Since exercise testing (ET) is also part of the assessment of ventilatory regulation the authors aimed to determine whether MOP and ET are sensitive and reliable parameters predictive of nocturnal O(2) saturation and clinical evolution. We conducted a Polysomnographic (PSG) study in two groups of 14 patients, selected according to their MOP level. Patients performed at admission an ET, Respiratory Function tests (RFT) and clinical evaluation with Norris spinal and bulbar scores (SNS and BNS). All patients in Group I (Low MOP) had decreased O(2) saturation during ET (P<0.001). Correlation study showed correlation between ET and MOP (R=0.6); PI(max) slope and PE(max) slope correlated with ET (R=-0.4; -0.6), respectively. ET also correlated with nocturnal O(2) saturation and SNS slope (R=0.8; -0.5), respectively. SNS and BNS slopes correlated with nocturnal O(2) saturation (R=-0.4; -0.7), respectively. The best correlations found were between MOP slope and BNS slope and SNS slope (R=0.8; 0.7), respectively. The high predictive values of MOP and ET at admission to nocturnal O(2) saturation (predicted value=80%) suggested the need of nocturnal pulse oximetry as a standard procedure. MOP and ET should also be used in evaluation protocols of ALS/MND.

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.

Bipap improves survival and rate of pulmonary function decline in patients with ALS

Amyotrophic Lateral Sclerosis (ALS) is a progressive motor neuron disease that frequently causes death within five years of diagnosis. The majority of deaths are due to pulmonary complications resulting from respiratory muscle weakness and bulbar involvement. A promising respiratory intervention is the recently introduced bi-level intermittent positive pressure (Bipap), which is a noninvasive ventilator modality shown to reduce the work of breathing and improve not only gas exchange, but also exercise tolerance and sleep quality. The aim of this study was to assess the utility of Bipap in prolonging survival in ALS. We retrospectively analyzed the results of Bipap use in 122 patients followed at Hahnemann University. All patients in this study were offered Bipap when their forced vital capacity (FVC) dropped below 50% of predicted value. Group 1 (n=38) accepted Bipap and used it more than 4 h/day. Group 2 (n=32) did not tolerate Bipap well and used it less than 4 h/day. Group 3 (n=52) refused to try Bipap. There was a statistically significant improvement in survival from initiation of Bipap in Group 1 (14.2 months) compared to Group 2 (7.0 months, P=0.002) or 3 (4.6 months, P<0.001) respectively. Furthermore, when the slope of vital capacity decline was examined, the group that used Bipap more than 4 h/day had slower decline in vital capacity (-3.5% change/month) compared to Group 2 (-5.9% change/month, P=0.02) and Group 3 (-8.3% change/month, P<0.001). We conclude that Bipap can significantly prolong survival and slow the decline of FVC in ALS. Our results suggest that all patients with ALS be offered Bipap when their FVC drops below 50%, at the onset of dyspnea, or when a rapid drop in %FVC is noted.

Respiratory aspects of neurological disease

Neurological disease may result in respiratory dysfunction; however the manifestations of respiratory dysfunction in such patients may be atypical because of wider effects of their underlying condition. In the present review we have considered separately acute neuromuscular respiratory disease (as well as aspects of respiratory muscle function relevant to intensive care), chronic neuromuscular respiratory disease, sleep related disorders, respiratory consequences of specific neurological diseases, and neurological features of respiratory disease. Approaches to specific clinical problems are discussed; in many instances this can be expedited by close cooperation with a respiratory physician. We suggest that management of respiratory dysfunction in neurological disease depends critically on three factors: firstly, knowledge of when respiratory dysfunction is likely to occur; secondly, maintaining a high index of clinical suspicion (specifically apparently vague symptoms should not be uncritically attributed to the underlying neurological condition); and, thirdly, the pursuing of appropriate investigations.

Measurement of health-related quality of life in patients with amyotrophic lateral sclerosis in clinical trials of new therapies

OBJECTIVES

Recent trials of amyotrophic lateral sclerosis (ALS) therapies have included the Sickness Impact Profile (SIP) to evaluate health-related quality of life (HQL). The purpose of this study was to assess the feasibility, psychometric properties, and interpretation of the Sickness Impact Profile in this setting.

METHODS

The Sickness Impact Profile was administered at baseline, 3, 6, and 9 months during a double-blind, placebo-controlled study of recombinant human insulin-like growth factor I. The frequency of missing Sickness Impact Profile data and administration time were recorded. Patients' scores on the Appel ALS (AALS) Rating Scale were used to identify a stable subgroup for reliability testing and clinically distinct groups for validity testing. Internal consistency reliability and reproducibility were evaluated using Cronbach's alpha and intraclass correlation coefficients, respectively. Analysis of variance (ANOVA) models and t tests were used to assess validity. Effect sizes and the responsiveness index were used to assess responsiveness.

RESULTS

At baseline, 259 (97%) patients completed a 30-minute Sickness Impact Profile interview. At subsequent assessments, response rates ranged from 92% to 97% and mean administration times ranged from 25 to 27 minutes. The overall Sickness Impact Profile score demonstrated alpha reliability and 3-month stability coefficients of 0.94 and 0.80, respectively. Baseline overall Sickness Impact Profile scores discriminated between patients in the two AALS-defined groups with a mean of 13.0+/-7.8 and 24.0+/-11.7 in the better and worse AALS groups, respectively. Similarly, mean overall SIP change scores discriminated patients progressing at different rates (slow to moderate = 4.00+/-7.97; rapid = 10.74+/-8.76). With few exceptions, dimension and category scores met similar criteria. Responsiveness statistics for the physical and overall Sickness Impact Profile scores were lower at 3 months and higher at 6 and 9 months.

CONCLUSIONS

The feasibility, psychometric, and interpretive findings support the validity of the Sickness Impact Profile for assessing outcomes of amyotrophic lateral sclerosis and its treatment. Based on these findings, we recommend including the Sickness Impact Profile in future amyotrophic lateral sclerosis clinical trials.

Polysomnographic studies in amyotrophic lateral sclerosis

We retrospectively reviewed 17 polysomnograms (PSG) in symptomatic amyotrophic lateral sclerosis (ALS) patients to assess the type and frequency of sleep disordered events and correlated these findings with pulmonary function tests (PFTs), presenting complaints, presence of bulbar dysfunction, and response to bi-level positive airway pressure (PAP) treatment. PSG revealed abnormalities in 16 patients. Complaints of orthopnea, daytime sleepiness (but not morning headaches) and a low negative inspiratory force (NIF) correlated with sleep disruption. However, neither the forced vital capacity (FVC) nor the NIF reliably predicted any specific PSG finding. Twelve of 13 patients treated with bi-level PAP responded favorably. Since the response to bi-level PAP is frequently gratifying, PSG should strongly be considered in ALS patients with suspected sleep disturbances.

Motor neuron disease presenting with respiratory failure

Respiratory failure accounts for the majority of deaths in amyotrophic lateral sclerosis (ALS) but only rarely is ALS diagnosed on the basis of respiratory insufficiency. We report four ALS patients presenting with acute respiratory failure. In three patients we have performed EMG needle examination of both hemidiaphragms which showed severe denervation. We reviewed 25 patients previously described presenting with respiratory failure. Almost all patients showed upper limbs weakness and diaphragm involvement; few patients had bulbar dysfunction. The prognosis of these patients is not always in permanent ventilator dependence. Rapidly progressive ventilatory failure may be a striking initial sign of ALS; the main reason is a weakened diaphragm. There are possibilities of significant improvement after a period of rest with ventilatory assistance. In the initial phase of the disease, bulbar dysfunction is not the more common reason of acute respiratory failure.

Home mechanical ventilation for amyotrophic lateral sclerosis: nasal compared to tracheostomy-intermittent positive pressure ventilation

People with amyotrophic lateral sclerosis (ALS) usually die from respiratory failure unless they use mechanical ventilation (MV). Many die of respiratory failure without being adequately informed about the available options, such as MV that can provide symptomatic relief and prolong survival. The traditional method of MV used for persons with ALS has been tracheostomy-intermittent positive pressure ventilation (IPPV). However, the advent of nasal-IPPV has provided a new option for relieving respiratory symptoms and prolonging survival among selected individuals. The ALS Association Data on 75 ALS patients using MV is reviewed. Twenty-five patients used nasal-IPPV, all started electively. Survival with nasal-IPPV ranged from 6 to 64 months for non-bulbar patients, or until the onset of severe bulbar dysfunction when nasal-IPPV no longer was effective. Fifteen of these non-bulbar patients used nasal-IPPV from 20 to 24 h daily; one of these patients used nasal-IPPV continuously for 24 h daily for 24 months. One hundred percent of the users indicated they were glad they chose nasal-IPPV. In contrast, 50 have used tracheostomy-IPPV, usually as a result of emergency hospitalization without advance decision making. Twenty-five patients (50%) lived in a sub-acute skilled nursing facility (SNF) and only 18 of these (72%) were satisfied with their quality of life. Patients using tracheostomy-IPPV with good care are able to live many years: 27 of the 50 (54%) are still living, including one patient who is still living after 14 years of MV. In conclusion, home mechanical ventilation with nasal or tracheostomy-IPPV are options for selected people with ALS. Nasal-IPPV offers may advantages; it was only used when MV was planned and desired. Nasal-IPPV can be used unless bulbar impairment is severe.