Impact of nasal ventilation on survival in hypercapnic Duchenne muscular dystrophy

[Pulmonary and nonpulmonary alterations in Duchenne muscular dystrophy]

OBJECTIVE

To describe our experience in managing patients with Duchenne muscular dystrophy.

PATIENTS AND METHODS

We analyzed the following variables in a group of 27 patients with Duchenne muscular dystrophy: arterial blood gases, lung function before and after mechanical ventilation, oxygen saturation (measured by pulse oximetry), nocturnal PaCO2 (measured transcutaneously by capnography), heart function, and dysphagia.

RESULTS

The mean (SD) age was 26 (6) years and the mean age at which mechanical ventilation had initiated in the patients was 21 (5) years. Sixty-two percent had undergone tracheostomy and invasive mechanical ventilation. Arterial blood gas levels returned to normal once mechanical ventilation was administered and remained so for the entire treatment period (mean duration of follow-up, 56 [49] months). Thirteen patients had cardiac symptoms and they all presented abnormal electrocardiograms and echocardiograms indicating dilated cardiomyopathy, left ventricular dysfunction, and posterior hypokinesis. Only 9 patients were receiving enteral nutrition (7 through a gastrostomy tube and 2 through a nasogastric tube). The videofluoroscopic swallowing study confirmed that dysphagia was related to neuromuscular disease rather than the presence or not of a tracheostomy. Five patients (18%), 4 of whom were receiving invasive mechanical ventilation, died during the follow-up period. Three patients had serious heart disease.

CONCLUSIONS

Mechanical ventilation confers clinical benefits and prolongs life expectancy in patients with Duchenne muscular dystrophy. Heart disease and feeding difficulties are determining factors in the prognosis of these patients.

A comparison of invasive versus noninvasive full-time mechanical ventilation in Duchenne muscular dystrophy

The aim of this study was to compare morbidity and causes of death in a series of 42 Duchenne patients receiving full-time mechanical ventilation either by tracheostomy (TR, n = 16 or by noninvasive methods (noninvasive ventilation [NIV], n = 26). At inclusion for a 5-year observation period (2002–2006), TR and NIV patients were 32.7 and 27 years old, respectively. A program of follow-up with similar ventilation devices, techniques of respiratory physiotherapy, and drugs was applied to all the patients [TR + NIV]. Ages and respiratory characteristics at death and causes of death were comparable between groups. Morbidity was worse in TR compared with NIV patients; mucus hypersecretion and tracheal injuries were more frequent, whereas loss of weight and need for gastric feeding appeared less frequent in the TR group. Because noninvasive techniques avoid the severe complications associated with TR with comparable mortality, the authors support the use of noninvasive interfaces as default choice when assisted ventilation is required for daytime use.

Sleep problems in children with neurological disorders

This review describes the complex and often reciprocal relationship between sleep problems, neurological disorders and/or intellectual disability in children. The causes of Intellectual disability (ID) discussed in this review include those conditions present from or around the time of birth, although it also considers traumatic brain injuries occurring later in development. This review discusses the patterns of sleep difficulty associated with specific disorders and summarizes the assessment and interventions, both behavioural and pharmacological, applicable to children. Many neurological disorders such as epilepsy, narcolepsy and neurorespiratory disorders vary considerably in terms of the degree of co-morbid problems and can present with a spectrum of effects on underlying cognitive or behavioural substrates including sleep function. These conditions are discussed as they provide useful insights into how disordered sleep can impact on cognitive development and behaviour. The review draws both on the literature in these areas and the extensive clinical experience of the authors.

Mechanical ventilation in Duchenne patients with chronic respiratory insufficiency: clinical implications of 20 years published experience

Chronic respiratory insufficiency is inevitable in the course of disease progression in patients with Duchenne muscular dystrophy (DMD). Without mechanical ventilation (MV), morbidity and mortality are highly likely towards the end of the second decade of life. The present review reports evidence and clinical implications regarding DMD patients treated with MV. There is no doubt that nocturnal hypercapnia precedes daytime hypercapnia. Historical comparisons have provided evidence that non-invasive intermittent positive pressure ventilation (NIPPV) at night is effective and improves quality of life and survival by 5-10 years. By contrast, the optimal criteria and timing for initiation of NIPPV are inconsistent. A recent randomized study however demonstrated the benefits of commencing NIPPV as soon as nocturnal hypoventilation is detected (Ward S, et al., Randomised controlled trial of non-invasive ventilation (NIV) for nocturnal hypoventilation in neuromuscular and chest wall disease patients with daytime normocapnia. Thorax 2005; 60: 1019-24). The respective role of the three hypotheses of the indirect action of nocturnal NIPPV on daytime blood gases may be complimentary; the main improvement may be due to improved ventilatory response to CO2. The ultimate time to offer full time ventilation with the most advantageous interface is lacking in evidence. Full time NIV is possible with a combination of a nasal mask during the night and a mouthpiece during the day, however tracheostomy may be provided when mechanical techniques of cough-assistance are useless to treat chronic cough insufficiency.

Mental retardation and lifetime events of Duchenne muscular dystrophy in Japan

OBJECTIVE

This study investigated the relationship between mental retardation and lifetime events in patients with Duchenne muscular dystrophy (DMD).

METHODS

The data on mental retardation and ages of lifetime events (first walking, loss of ambulation, introductions of ventilator support and tube nutrition and death) were collected retrospectively, and the relationships between the factors were analyzed.

PATIENTS

Among 194 DMD patients admitted to our hospital between 1995 and 2007, 74 patients underwent evaluation of their intelligence quotient (IQ).

RESULTS

Twenty-eight patients (38%) demonstrated mental retardation (IQ<70). DMD patients with mental retardation started walking later, required ventilator and tube nutrition support earlier, and died earlier than those without mental retardation.

CONCLUSIONS

Since the prognosis of DMD patients with mental retardation was worse than that of those without mental retardation, more careful treatment is necessary for DMD patients with mental retardation.

Heart rate variability and hypercapnia in Duchenne muscular dystrophy

OBJECTIVE

To investigate the relationship between heart rate variability and hypercapnia.

PATIENTS AND METHODS

We measured the coefficient of variation of R-R interval (CVrr) and arterial blood gas pressures in 73 patients with Duchenne muscular dystrophy.

RESULTS

CVrr was negatively correlated with arterial partial pressure of carbon dioxide (PaCO(2)). In patients whose CVrr was larger than 5%, 84% of them had no hypercapnia while the other 16% had hypercapnia (PaCO(2) >45 mmHg). In contrast, 27% of those with CVrr smaller than 3% had no hypercapnia, 73% had hypercapnia and 47% had severe hypercapnia (PaCO(2) >50 mmHg).

CONCLUSION

We first showed that CVrr was negatively correlated with PaCO(2), and propose that abnormally low CVrr indicates respiratory insufficiency in patients with Duchenne muscular dystrophy.

Local dystrophin restoration with antisense oligonucleotide PRO051

BACKGROUND

Duchenne's muscular dystrophy is associated with severe, progressive muscle weakness and typically leads to death between the ages of 20 and 35 years. By inducing specific exon skipping during messenger RNA (mRNA) splicing, antisense compounds were recently shown to correct the open reading frame of the DMD gene and thus to restore dystrophin expression in vitro and in animal models in vivo. We explored the safety, adverse-event profile, and local dystrophin-restoring effect of a single, intramuscular dose of an antisense oligonucleotide, PRO051, in patients with this disease.

METHODS

Four patients, who were selected on the basis of their mutational status, muscle condition, and positive exon-skipping response to PRO051 in vitro, received a dose of 0.8 mg of PRO051 injected into the tibialis anterior muscle. A biopsy was performed 28 days later. Safety measures, composition of mRNA, and dystrophin expression were assessed.

RESULTS

PRO051 injection was not associated with clinically apparent adverse events. Each patient showed specific skipping of exon 51 and sarcolemmal dystrophin in 64 to 97% of myofibers. The amount of dystrophin in total protein extracts ranged from 3 to 12% of that found in the control specimen and from 17 to 35% of that of the control specimen in the quantitative ratio of dystrophin to laminin alpha2.

CONCLUSIONS

Intramuscular injection of antisense oligonucleotide PRO051 induced dystrophin synthesis in four patients with Duchenne's muscular dystrophy who had suitable mutations, suggesting that further studies might be feasible.

Chronic respiratory failure in patients with neuromuscular diseases: diagnosis and treatment

Neuromuscular diseases affect alveolar air exchange and therefore cause chronic respiratory failure. The onset of respiratory failure can be acute, as in traumas, or progressive (slow or rapid), as in amyotrophic lateral sclerosis, muscular dystrophies, diseases of the myoneural junction, etc. Respiratory muscle impairment also affects cough efficiency and, according to the current knowledge regarding the type of treatment available in Brazil to these patients, it can be said that the high rates of morbidity and mortality in these individuals are more often related to the fact that they cough inefficiently rather than to the fact that they ventilate poorly. In this review, with the objective of presenting the options of devices available to support and substitute for natural ventilation in patients with neuromuscular diseases, we have compiled a brief history of the evolution of orthopedic braces and prostheses used to aid respiration since the end of the 19th century. In addition, we highlight the elements that are fundamental to the diagnosis of alveolar hypoventilation and of failure of the protective cough mechanism: taking of a clinical history; determination of peak cough flow; measurement of maximal inspiratory and expiratory pressures; spirometry in two positions (sitting and supine); pulse oximetry; capnography; and polysomnography. Furthermore, the threshold values available in the literature for the use of nocturnal ventilatory support and for the extension of this support through the daytime period are presented. Moreover, the maneuvers used to increase cough efficiency, as well as the proper timing of their introduction, are discussed.

When should home mechanical ventilation be started in patients with different neuromuscular disorders?

BACKGROUND AND OBJECTIVES

Current international consensus guidelines identify a number of indicators for the establishment of home mechanical ventilation (HMV) for patients with neuromuscular diseases but do not address the possible clinical differences between each of the underlying disorders. This study assessed the differences in the physiological parameters of patients with neuromuscular disease commenced on HMV for the treatment of symptomatic chronic hypercapnic respiratory failure.

METHODS

Patients commenced on HMV for the treatment of symptomatic chronic hypercapnic respiratory failure over a 9-year period were studied. Physiological parameters at the time of referral for HMV, impact of HMV and survival were analysed.

RESULTS

The study recruited 66 patients with neuromuscular disease. Thirty-one patients had rapidly progressive disease: amyotrophic lateral sclerosis (ALS, n = 19), Duchenne muscular dystrophy (DMD, n = 12) and 35 patients had slowly progressive disease. Mean FVC at HMV onset was 40.3 +/- 17.5% predicted in all patients, but was >50% predicted in eight patients (12%). ALS patients were more hypercapnic (P = 0.03) and more hypoxaemic (P < 0.001), but had better FEV(1) at HMV onset, compared with DMD patients (P = 0.005). Maximal inspiratory mouth occlusion pressure (PImax) was 3.0 +/- 1.6 kPa in all patients, but values were lower compared with international consensus guidelines (5.88 kPa). Median survival in DMD, slowly progressive diseases and ALS was 132, 82 and 16 months, respectively (P < 0.001).

CONCLUSIONS

Blood gases and lung function parameters vary substantially between patients with differing underlying neuromuscular disorders when commenced on HMV for the treatment of symptomatic chronic hypercapnic respiratory failure. In contrast, PImax is equally reduced in all patients and more severely reduced compared with consensus guidelines. The specific underlying neuromuscular disease has a major impact on outcome. Specific selection criteria are needed for the use of HMV in the different diseases that comprise neuromuscular disorders.

Correlations of Egen Klassifikation and Barthel Index scores with pulmonary function parameters in Duchenne muscular dystrophy

PURPOSE

This study investigated the correlations obtained by using the Egen Klassifikation (EK) and Barthel Index (BI) functional scales and respiratory function parameters in patients with Duchenne muscular dystrophy.

METHODS

Spirometry, maximal respiratory pressures, and arterial blood gases were analyzed and graded according to the EK and BI scales in 26 patients. They were classified as high or low risk for introduction of noninvasive ventilation according to the respiratory function.

RESULTS

The EK and BI scales significantly correlated with forced vital capacity, forced expiratory volume in 1 second, and maximal respiratory pressures. The worse the functional performance, the worse the respiratory measurements. The degree of correlation between the functional scales and each respiratory parameter was similar. An EK of 21 or higher predicted high risk for the introduction of noninvasive ventilation.

CONCLUSIONS

EK and BI scales similarly correlated with the degree of respiratory involvement in Duchenne muscular dystrophy. The EK scale was superior in detecting subjects with a higher risk for introduction of noninvasive ventilation.

Laparoscopic Nissen fundoplication during gastrostomy tube placement and noninvasive ventilation may improve survival in type I and severe type II spinal muscular atrophy

Progressive respiratory muscle weakness with bulbar involvement is the main cause of morbidity and mortality in type I and severe type II spinal muscular atrophy. Noninvasive positive pressure ventilation techniques coupled with laparoscopic gastrointestinal procedures may allow for improved morbidity and mortality. The authors present a series of 7 spinal muscular atrophy patients (6 type I and 1 severe type II) who successfully underwent laparoscopic gastrostomy tube insertion coupled with Nissen fundoplication and early postoperative extubation using noninvasive positive pressure ventilation techniques. The authors measured the length of survival and the frequencies of pneumonia and hospitalization before and after surgery as outcomes of these new surgical and medical interventions. All 7 patients had respiratory symptoms (unmanageable oropharyngeal secretions, cough, pneumonia), difficulty feeding, and weight loss. Six patients had documented reflux via diagnostic testing preoperatively. Five patients were on noninvasive positive pressure ventilation and other supportive respiratory therapies prior to surgery. All 7 patients survived the procedures. By August 2006, 5 patients with type I and 1 with severe type II spinal muscular atrophy were alive and medically stable at home 1.5 months to 41 months post-op. One patient with type I expired approximately 5 months post-op due to obstructive apnea. This case series demonstrates that laparoscopic gastrostomy tube placement coupled with Nissen fundoplication and noninvasive positive pressure ventilation can be successfully used as a treatment option to allow for early postoperative extubation and to optimize quality of life in type I and severe type II spinal muscular atrophy patients.

Current treatment of adult Duchenne muscular dystrophy

Patients with Duchenne muscular dystrophy (DMD) are living longer into adulthood due to a variety of improvements in health care practices. This growing patient population presents new therapeutic challenges. In this article, we review the literature on current treatment of adult DMD as well as our own experience as a multidisciplinary team actively caring for 23 men ages 19-38 years of age. Approximately one quarter of our adult DMD patients have remained on moderate dose corticosteroids. Daily stretching exercises are recommended, particularly of the distal upper extremities. Cardiomyopathy is anticipated, detected, and treated early with afterload reduction. Oxygen saturation monitoring, noninvasive positive pressure ventilation and cough assist devices are routinely used. Other medical issues such as osteoporosis, gastrointestinal and urinary symptoms are addressed. Current and future therapies directed at prolonging the lifespan of those with DMD will result in further increases in this adult population with special needs and concerns. These needs are best addressed in a multidisciplinary clinic.

Recent Advances in Respiratory Care for Neuromuscular Disease

The impact of ventilatory support on the natural history of neuromuscular disease (NMD) has become clearer over the last 2 decades as techniques have been more widely applied. Noninvasive ventilation (NIV) allows some patients with nonprogressive pathology to live to nearly normal life expectancy, extends survival by many years in patients with other conditions (eg, Duchenne muscular dystrophy), and in those patients with rapidly deteriorating disease (eg, amyotrophic lateral sclerosis) survival may be increased, but symptoms can be palliated even if mortality is not reduced. A growing number of children with NMD are surviving to adulthood with the aid of ventilatory support. The combination of NIV with cough-assist techniques decreases pulmonary morbidity and hospital admissions. Trials have confirmed that NIV works in part by enhancing chemosensitivity, and in patients with many different neuromuscular conditions the most effective time to introduce NIV is when symptomatic sleep-disordered breathing develops.

Outcome of non-invasive domiciliary ventilation in elderly patients

STUDY OBJECTIVES

To analyze the short- and long-term effects of domiciliary non-invasive ventilation (NIV) in the elderly.

METHODS

From 1990 to 2005 all patients who initiated NIV at age 75 or older were included in the study. The mean follow-up period was 36 (24) months. Data were obtained from a database record.

RESULTS

Forty-three patients, mean age 77 (1.9) years and hypercapnic respiratory failure secondary to restrictive, neuromuscular or hypoventilatory disease were included. The short-term effects included a significant improvement in arterial blood gases and nocturnal desaturations during NIV compared to baseline: PaO(2) increased a mean of 19 mmHg (P<0.0001), PaCO(2) decreased a mean of 16 mmHg (P<0.0001) and nocturnal time with SaO(2)<90% decreased a mean of 72% (P<0.0001). Arterial blood gases while breathing room air also improved significantly at 6 months after NIV initiation. Five patients (11%) discontinued treatment; this group did not differ from patients who continued NIV. Mean compliance was 8.3 (3.1)h/day. In the long-term effects, we observed that the initial improvement of arterial blood gases breathing room air was maintained throughout the followup period. The number of hospital admissions and days of hospital stay decreased significantly (P<0.0001 and 0.001, respectively) after NIV initiation. The poorest survival was observed in ALS patients (median 10.9 (2.3) months) significantly lower than the survival for the other diagnostic groups (median 58.5 (4.8) months), P=0.0013.

CONCLUSIONS

NIV is an effective treatment in the elderly. It improves arterial blood gases and nocturnal desaturations, decreases hospital admissions and is associated with long survival. So advanced age should not be considered as an exclusion criteria to prescribe NIV.

Respiratory involvement in inherited primary muscle conditions

Patients with inherited muscle disorders can develop respiratory muscle weakness leading to ventilatory failure. Predicting the extent of respiratory involvement in the different types of inherited muscle disorders is important, as it allows clinicians to impart prognostic information and offers an opportunity for early interventional management strategies. The approach to respiratory assessment in patients with muscle disorders, the current knowledge of respiratory impairment in different muscle disorders and advice on the management of respiratory complications are summarised.

Correction of neuromuscular scoliosis in patients with preexisting respiratory failure

STUDY DESIGN

A prospective observational study in scoliosis patients who were on noninvasive night ventilation for respiratory failure.

OBJECTIVE

To report the results of spinal deformity correction in a group of patients with progressive scoliosis and rare forms of muscular dystrophy/myopathy with respiratory failure who were on nocturnal ventilatory support at the time of surgery.

SUMMARY OF BACKGROUND DATA

This is the first study on the results of deformity correction in a series of patients on ventilatory support.

MATERIALS AND METHODS

Eight patients (6 males, 2 females) presented with progressive scoliosis and respiratory failure. The mean age at surgery was 12 years (range, 8-15 years). The mean follow-up was 48 months (range, 12-80 months). Outcome measures include lung function (spirometry), overnight pulse oximetry, Cobb angles, duration of stay in Intensive care (ICU), and the total hospital stay.

RESULTS

The mean stay in the ICU was 2.7 days (range, 2-5 days). The mean hospital stay was 14.2 days (range, 10-21 days). The mean preoperative Cobb angle was 70.2 degrees (55 degrees -85 degrees ). This changed to 32 degrees (16 degrees -65 degrees ) after surgery (P = 0.0002). The mean vital capacity at the time of surgery was 20% (range, 13%-28%). The mean vital capacity of patients at last follow-up was 18% (range, 10%-31%). The desaturation noted on the preventilation overnight oximetry was reversed by nocturnal ventilation. All patients recovered well following surgery with no major cardiac or pulmonary complications.

CONCLUSION

Patients with preexisting respiratory failure on nocturnal noninvasive ventilation can be safely operated for deformity correction. This can help to significantly improve their quality of life.

Left ventricular function and response to enalapril in patients with duchenne muscular dystrophy during the second decade of life

The role of angiotensin-converting enzyme inhibitors in the management of cardiomyopathy related to Duchenne muscular dystrophy has not been completely defined. The purposes of this study were to describe the response to enalapril and its relation to dystrophin mutation type, ventricular size, or age at the onset of left ventricular (LV) systolic dysfunction. Serial clinical and echocardiographic data from 50 patients with Duchenne muscular dystrophy (aged 10 to 20 years) were retrospectively reviewed. Twenty-seven patients (46%) developed LV systolic dysfunction (mean age 13.2 +/- 2.4 years). Ten (43%) responded to enalapril with the normalization of function. Responders and nonresponders developed LV systolic dysfunction at similar ages (p = 0.91). At the onset of LV systolic dysfunction, only 2 patients (1 responder, 1 nonresponder) had dilated left ventricles. The positive response to enalapril was sustained in 7 patients (median follow-up 23 months, range 5 to 58). No specific mutation was associated with the response to enalapril (p = 0.66) or predictive of the development of LV systolic dysfunction (p = 0.8). In conclusion, 10 of 26 patients (43%) with Duchenne muscular dystrophy responded to the use of enalapril with normalization of the shortening fraction. Age at the onset of LV systolic dysfunction and the type of mutation were not predictors of response to enalapril.

[Home ventilatory assistance in Chilean children: 12 years' experience]

OBJECTIVE

Home ventilatory support systems are a treatment option for patients with severe chronic respiratory failure. The objective of the present study was to characterize the children admitted to a home ventilatory assistance program.

PATIENTS AND METHOD

The home ventilation program was created by our hospital to coordinate professional and technological support for chronic ventilator-dependent children. We revised and updated information on patient characteristics, type of assisted ventilation, respiratory morbidity, and equipment failures between 1993 and 2004.

RESULTS

Follow-up of 35 children (18 male) was carried out by our hospital staff. Median age upon admission to the program was 12 months (range, 5 months to 14 years). Median length of time in the program was 21 months and we were able to wean 40% of patients from ventilators. Six patients died. The main indications for assisted ventilation were neuromuscular disease (12 cases), airway abnormality (11 cases), cardiopulmonary disease (7 cases), and hypoventilation syndrome (5 cases). The types of assisted ventilation used were continuous positive airway pressure (in 17 cases), bilevel positive pressure (in 8 cases), and synchronized intermittent mandatory ventilation (in 10 cases). Invasive ventilation via a tracheostomy was used in 26 cases. The use of noninvasive ventilation increased in the last 4 years. Respiratory morbidity (pneumonia and bacterial tracheitis) was the most frequent cause of hospitalization and the annual rate of such episodes was 1.6 per child. The annual rate of hospitalization due to equipment failures was 0.1 per child.

CONCLUSION

The program provides safe and necessary home ventilatory assistance for children with severe chronic respiratory failure. The professional support that home hospitalization offers had a positive effect on outcome in these children. It is important to take our experience into account in creating a Chilean national home ventilatory assistance program.

Therapeutics in duchenne muscular dystrophy

Duchenne muscular dystrophy (DMD) is a fatal disorder affecting approximately 1 in 3,500 live born males, characterized by progressive muscle weakness. Several different strategies are being investigated in developing a cure for this disorder. Until a cure is found, therapeutic and supportive care is essential in preventing complications and improving the afflicted child's quality of life. Currently, corticosteroids are the only class of drug that has been extensively studied in this condition, with controversy existing over the use of these drugs, especially in light of the multiple side effects that may occur. The use of nutritional supplements has expanded in recent years as researchers improve our abilities to use gene and stem cell therapies, which will hopefully lead to a cure soon. This article discusses the importance of therapeutic interventions in children with DMD, the current debate over the use of corticosteroids to treat this disease, the growing use of natural supplements as a new means of treating these boys and provides an update on the current state of gene and stem cell therapies.

Nonmolecular treatment for muscular dystrophies

PURPOSE OF REVIEW

This review highlights emerging evidence on the management of patients with muscular dystrophies.

RECENT FINDINGS

New diagnostic modalities based on muscle biopsy and DNA analysis mean that diagnoses within the heterogeneous group of muscular dystrophies can be much more precise; also, as the phenotypes associated with these different disorders are clarified, new management implications can be recognized. At the same time, the spread of evidence based medicine into this area has led to an increase in clinical trial activity and the development of evidence based guidelines. Because many if not all muscular dystrophies are multisystem disorders, these guidelines relate not only to the limited number of interventions aimed at improving strength but also to the management of potentially life threatening complications.

SUMMARY

Because specific diagnoses carry specific management implications in many areas for these hitherto rather neglected disorders, a more proactive approach to patients with muscular dystrophies is needed. Complications involving, for example, the cardiovascular, respiratory and gastrointestinal systems may need to be sought and actively managed, whereas caution for complications of anaesthesia and other interventions may also be necessary. However, areas remain where there is little evidence from which practice guidelines can be developed and these will need to be addressed with well planned clinical trials.

The effects of nocturnal home mechanical ventilation on daytime blood gas disturbances

INTRODUCTION

In chronic alveolar hypoventilation, previous studies of selected patient groups have shown that nocturnal home mechanical ventilation (HMV) may result in improvements in chronic blood gas disturbances during daytime spontaneous breathing. We wished to examine the effects of this treatment in a large sample of non-selected patients prospectively followed up, in a national multicentric register.

MATERIAL

A total of 288 patients from a broad diagnostic spectrum were studied. We looked at the blood gases and vital capacity before the patients elected for initiation of HMV and at the first register-recorded follow-up after 6-24 months.

RESULTS

We found statistically significant improvements in PO(2) and PCO(2) (approximately 1 kPa in both) and in base excess, but no changes in vital capacity or calculated alveolo-arterial gradient. All changes were independent of the observation period and only weakly diagnose-related.

DISCUSSION

Our findings extend those of previous studies, showing a relatively early and apparently stable improvement in blood gases after starting and continuing nocturnal HMV. The equal extent of the improvements in blood gases among all the diagnostic groups including the neurological patients with progressive diseases was unexpected.

CONCLUSION

In 288 patients starting nocturnal HMV electively we found significant improvements in daytime blood gases after 6-24 months. There were no changes in vital capacity or calculated alveolo-arterial gradient.

Diaphragmatic function in advanced Duchenne muscular dystrophy

The aim of this study was to assess diaphragm electrical activation and diaphragm strength in patients with advanced Duchenne muscular dystrophy during resting conditions. Eight patients with advanced Duchenne muscular dystrophy (age of 25 +/- 2 years) were studied during tidal breathing, maximal inspiratory capacity, maximal sniff inhalations, and magnetic stimulation of the phrenic nerves. Six patients were prescribed home mechanical ventilation (five non-invasive and one tracheotomy). Transdiaphragmatic pressure and diaphragm electrical activation were measured using an esophageal catheter. During tidal breathing (tidal volume 198 +/- 83 ml, breathing frequency 25 +/- 7), inspiratory diaphragm electrical activation was clearly detectable in seven out of eight patients and was 12 +/- 7 times above the noise level, and represented 45 +/- 19% of the maximum diaphragm electrical activation. Mean inspiratory transdiaphragmatic pressure during tidal breathing was 1.5 +/- 1.2 cmH2O, and during maximal sniff was 7.6 +/- 3.6 cmH2O. Twitch transdiaphragmatic pressure deflections could not be detected. This study shows that despite near complete loss of diaphragm strength in advanced Duchenne muscular dystrophy, diaphragm electrical activation measured with an esophageal electrode array remains clearly detectable in all but one patient.

Noninvasive ventilation during gastrostomy tube placement in patients with severe duchenne muscular dystrophy: case reports and review of the literature

Individuals with Duchenne muscular dystrophy may benefit from gastrostomy tube feeding due to progressive dysphagia and malnutrition. However, due to their severely impaired pulmonary function, these individuals are at risk of severe complications when they are sedated or undergo anesthesia for the procedure. We previously described a technique of noninvasive positive pressure ventilation to provide respiratory support during gastrostomy tube placement in such patients, but this technique had risks and limitations. In this case report, we examine two alternative techniques we used to provide respiratory support successfully to patients with severe muscular dystrophy and malnutrition who underwent percutaneous endoscopic gastrostomy tube placement. We then review the literature and discuss the potential benefits, risks, and limitations of the above techniques and of other options for gastrostomy placement in people with severe muscular dystrophy.

Randomised controlled trial of non-invasive ventilation (NIV) for nocturnal hypoventilation in neuromuscular and chest wall disease patients with daytime normocapnia

BACKGROUND

Long term non-invasive ventilation (NIV) reduces morbidity and mortality in patients with neuromuscular and chest wall disease with hypercapnic ventilatory failure, but preventive use has not produced benefit in normocapnic patients with Duchenne muscular dystrophy. Individuals with nocturnal hypercapnia but daytime normocapnia were randomised to a control group or nocturnal NIV to examine whether nocturnal hypoventilation is a valid indication for NIV.

METHODS

Forty eight patients with congenital neuromuscular or chest wall disease aged 7-51 years and vital capacity<50% predicted underwent overnight respiratory monitoring. Twenty six with daytime normocapnia and nocturnal hypercapnia were randomised to either nocturnal NIV or to a control group without ventilatory support. NIV was started in the control group if patients fulfilled preset safety criteria.

RESULTS

Peak nocturnal transcutaneous carbon dioxide tension (Tcco2) did not differ between the groups, but the mean (SD) percentage of the night during which Tcco2 was >6.5 kPa decreased in the NIV group (-57.7 (26.1)%) but not in controls (-11.75 (46.1)%; p=0.049, 95% CI -91.5 to -0.35). Mean (SD) arterial oxygen saturation increased in the NIV group (+2.97 (2.57)%) but not in controls (-1.12 (2.02)%; p=0.024, 95% CI 0.69 to 7.5). Nine of the 10 controls failed non-intervention by fulfilling criteria to initiate NIV after a mean (SD) of 8.3 (7.3) months.

CONCLUSION

Patients with neuromuscular disease with nocturnal hypoventilation are likely to deteriorate with the development of daytime hypercapnia and/or progressive symptoms within 2 years and may benefit from the introduction of nocturnal NIV before daytime hypercapnia ensues.

Cardiovascular health supervision for individuals affected by Duchenne or Becker muscular dystrophy

Duchenne muscular dystrophy is the most common and severe form of the childhood muscular dystrophies. The disease is typically diagnosed between 3 and 7 years of age and follows a predictable clinical course marked by progressive skeletal muscle weakness with loss of ambulation by 12 years of age. Death occurs in early adulthood secondary to respiratory or cardiac failure. Becker muscular dystrophy is less common and has a milder clinical course but also results in respiratory and cardiac failure. The natural history of the cardiomyopathy in these diseases has not been well established. As a result, patients traditionally present for cardiac evaluation only after clinical symptoms become evident. The purpose of this policy statement is to provide recommendations for optimal cardiovascular evaluation to health care specialists caring for individuals in whom the diagnosis of Duchenne or Becker muscular dystrophy has been confirmed.

Trends in survival from muscular dystrophy in England and Wales and impact on respiratory services

Respiratory failure is an important terminal event in muscular dystrophy, but increasingly is effectively treated by non-invasive ventilation. This study was designed to assess mortality statistics in this patient group in order to get an indication of future demand. Mortality data for all deaths from muscular dystrophy registered by death certification in England and Wales between 1993 and 1999 were analysed. In total, 817 deaths from muscular dystrophy were registered between 1993 and 1999. Annual number of deaths was unchanged over this period. Median age at death (interquartile range) for all cause muscular dystrophy increased from 20 (17-42.5) years in 1993, to 26 (17.5-63) years in 1999. Respiratory failure was the primary or contributory cause of death in 82% of cases. Two thirds of these deaths were during acute infection. We can expect 100 patients with muscular dystrophy to develop respiratory failure in England and Wales each year, so non-invasive ventilation services probably need to be able to provide for 0.2 new patients per 100,000 population annually. Respiratory services also need to provide adequate monitoring and early treatment of infection in these patients.

Quality of Life, Physical Disability, and Respiratory Impairment in Duchenne Muscular Dystrophy

RATIONALE

Duchenne muscular dystrophy (DMD) leads to progressive, generalized paresis, and to respiratory failure in the second decade of life. The assumption that severe physical disability precludes an acceptable quality of life is common, but has not been specifically evaluated in DMD.

OBJECTIVES

The purpose of this study was to investigate the quality of life in relation to physical disability, pulmonary function, and the need for assisted ventilation in DMD.

METHODS

In 35 patients with DMD, aged 8-33 yr, we assessed physical disability by a score ranging from 9 (no disability) to 80 (complete dependence on care and technical aids), pulmonary function, and health-related quality of life by Short-Form 36 of the medical outcome questionnaire.

MEASUREMENTS AND MAIN RESULTS

All patients required a wheelchair and help for dressing and eating. Fourteen patients were on long-term noninvasive positive-pressure ventilation. In ventilated patients, mean +/- SD FVC was 12 +/- 10 % predicted, and the physical disability score was 65 +/- 7. Corresponding values in spontaneously breathing patients were 48 +/- 25 % predicted, and 51 +/- 7, respectively (p < 0.05 for both comparisons between groups). Short-Form 36 physical function scores were massively reduced in both groups (1 +/- 2, and 0 +/- 0, respectively), but vitality, role-emotional, social function, and mental health scores were nearly normal (67-98), and did not differ between groups.

CONCLUSIONS

Quality of life in DMD is not correlated with physical impairment nor the need for noninvasive positive-pressure ventilation. The surprisingly high quality of life experienced by these severely disabled patients should be taken into consideration when therapeutic decisions are made.

Analysis of an adult Duchenne muscular dystrophy population

BACKGROUND

Advances in management have led to increasing numbers of patients with Duchenne muscular dystrophy (DMD) reaching adulthood. Older patients with DMD are necessarily severely disabled, and their management presents particular practical issues.

AIM

To review the management of a late adolescent and adult DMD population, and to identify areas in which the present service provisions may be inadequate to their needs.

DESIGN

Retrospective review.

METHODS

We studied 25 patients with DMD referred to an adult neuromuscular clinic over a 7-year period. Clinical details were obtained retrospectively, from case notes or direct observations.

RESULTS

There were 24 males and one symptomatic female carrier. Nine patients died during the observation period. There was no significant correlation between age of wheelchair confinement and age of death. Sixteen patients received non-invasive positive pressure support. Twelve attended mainstream schools and 12, residential special schools. All the patients lived at home for some or all of the time, when their main carers were either one or both of the parents. The most striking difficulties were with the provision of practical aids, including appropriate hoists and belts, feeding and toileting aids, and the conversion of accommodation. Patients rarely wished to discuss the later stages of their disease, and death was often more precipitate than expected. Death usually occurred outside hospital and the final cause was often difficult to establish.

DISCUSSION

Adult patients with DMD develop progressive impairment, due to respiratory, orthopaedic and general medical factors. However, the particular areas of difficulty in this study often reflected inadequate and poorly directed social and medical support, illustrating the need for improvements in the structure, co-ordination and breadth of rehabilitation services for adult patients with DMD.

Sleep-related breathing disorder in Duchenne muscular dystrophy: disease spectrum in the paediatric population

Duchenne muscular dystrophy (DMD) is a progressive neuromuscular disease with death usually occurring because of respiratory failure. Signs of early respiratory insufficiency are usually first detectable in sleep.

OBJECTIVE

To study the presentation of sleep-related breathing disorder (SRBD) in patients with DMD.

METHOD

A retrospective review of patients with DMD attending a tertiary paediatric sleep disorder clinic over a 5-year period. Symptoms, lung function and polysomnographic indices were reviewed.

RESULTS

A total of 34 patients with DMD were referred for respiratory assessment (1-15 years). Twenty-two (64%) reported sleep-related symptomatology. Forced vital capacity (FVC) was between 12 and 107% predicted (n = 29). Thirty-two progressed to have polysomnography of which 15 were normal studies (median age: 10 years) and 10 (31%) were diagnostic of obstructive sleep apnoea (OSA) (median age: 8 years). A total of 11 patients (32%) showed hypoventilation (median age: 13 years) during the 5-year period and non-invasive ventilation (NIV) was offered to them. The median FVC of this group was 27% predicted. There was a significant improvement in the apnoea/hypopnoea index (AHI) (mean difference = 11.31, 95% CI = 5.91-16.70, P = 0.001) following the institution of NIV.

CONCLUSIONS

The prevalence of SRBD in DMD is significant. There is a bimodal presentation of SRBD, with OSA found in the first decade and hypoventilation more commonly seen at the beginning of the second decade. Polysomnography is recommended in children with symptoms of OSA, or at the stage of becoming wheelchair-bound. In patients with the early stages of respiratory failure, assessment with polysomnography-identified sleep hypoventilation and assisted in initiating NIV.

Ethical aspects of home long term ventilation in children with neuromuscular disease

Increasing numbers of children and young adults are now receiving home ventilation. Whereas in some neuromuscular conditions the outcome and quality of life gains are clear cut; in others eg Spinal Muscular Atrophy Type I there are a few outcome studies with conflicting results and it is more difficult to balance the ethical concepts of beneficence, non-maleficence, autonomy and distributive justice. As a result there are widespread variations in the clinical management of these children. This article examines decision-making in these areas seen from the perspective of the individual, the family and society.

Noninvasive ventilation options in pediatric myasthenia gravis

A 10-month-old female infant with congenital myasthenic syndrome suffering from acute respiratory failure was supported using face mask positive pressure ventilation until definitive diagnosis and specific treatment was achieved. A 12-year-old girl suffering from seronegative myasthenia gravis was treated by helmet-delivered noninvasive ventilation during recurrent myasthenic episodes. Noninvasive support was really beneficial in the myasthenic crisis with respiratory muscle weakness, whereas a shift to tracheal intubation was necessary when pulmonary infection and multiple atelectasis occurred. The new helmet interface for noninvasive positive pressure ventilation can represent a valuable means of respiratory support in the early phase of respiratory failure in older children.

Respiratory management of the infant with type 1 spinal muscular atrophy

A recent paper has highlighted the differences in the respiratory management offered to infants with type 1 spinal muscular atrophy (SMA-1). Current views appear polarised between those who would offer nothing, to those who would proceed as far even as tracheostomy and long term invasive ventilation for these infants. Here we offer a personal view, as a possible template for managing a vexed and emotional problem. The complex non-respiratory aspects of the holistic care of these infants will not be discussed.

Cough determinants in patients with neuromuscular disease

Neuromuscular disease leads to cough impairment. Cough augmentation can be achieved by mechanical insufflation (MI) or manually assisted coughing (MAC). Many studies have compared these two methods, but few have evaluated them in combination. In 155 neuromuscular patients, we assessed determinants of peak cough flow (PCF) using stepwise correlation. Maximal inspiratory capacity contributed 44% of the variance (p<0.001), expiratory reserve volume 13%, and maximal expiratory pressure 2%. Thus, augmenting inspiration seems crucial. However, parameters dependent on expiratory muscles independently influence PCF. We measured vital capacity and PCF in 10 neuromuscular patients during cough augmentation by MI, MAC, or both. MI or MAC significantly improved VC and PCF (p<0.01) as compared to the basal condition and VC and PCF were higher during MI plus MAC than during MAC or MI alone (p<0.01). In conclusion, combining MAC and MI is useful for improving cough in neuromuscular patients.

L’assistance ventilatoire non invasive à domicile chez l’enfant

INTRODUCTION

Non-invasive positive pressure ventilation (NPPV) represents a particularly interesting technique of ventilatory support in paediatrics. Indeed, a significant number of pathologies that may be responsible for chronic respiratory insufficiency in childhood, such as neuromuscular diseases, obstruction of the upper airways, disorders of chest wall and/or the lungs, and disorders of ventilatory control may all lead to alveolar hypoventilation that can be improved by ventilatory support.

BACKGROUND

Few physiological studies have been performed on NPPV in children. The most appropriate modes and settings for each pathology have not been clearly defined, and the criteria for commencing NPPV are based essentially on consensus guidelines for the management of neuromuscular disorders.

VIEWPOINT

All the health care professionals managing these children should combine their efforts to evaluate more precisely the medium and long-term physiological effects of NPPV on the respiratory muscles, the development of the respiratory system, inspiratory activity, the indications for starting treatment and, above all, the benefits in terms of psycho-neurological development and quality of life.

CONCLUSIONS

A better evaluation of the medium and long-term physiological and psychological benefits together with technical improvements in ventilators and associated equipment should allow a rapid expansion in the use of domiciliary NPPV in children.

Noninvasive ventilation for the management of pulmonary hypertension associated with congenital heart disease in children

The use of noninvasive ventilation to support children with secondary pulmonary hypertension has not previously been reported. We present four children with secondary pulmonary hypertension in association with complex congenital and acquired cardiorespiratory anomalies who have been successfully managed in hospital and then discharged into the community on noninvasive ventilation, thus placing them in environments more suited for growth and development.

Long-term mechanical ventilation and nutrition

Mechanical ventilation (MV) in chronic situations is commonly used, either delivered invasively or by means of non-invasive interfaces, to control hypoventilation in patients with chest wall, neuromuscular or obstructive lung diseases (either in adulthood or childhood). The global prevalence of ventilator-assisted individuals (VAI) in Europe ranges from 2 to 30 per 100000 population according to different countries. Nutrition is a common problem to face with in patients with chronic respiratory diseases: nonetheless, it is a key component in the long-term management of underweight COPD patients whose muscular disfunction may rapidly turn to peripheral muscle waste. Since long-term mechanical ventilation (LTMV) is usually prescribed in end-stage respiratory diseases with poor nutritional status, nutrition and dietary intake related problems need to be carefully assessed and corrected in these patients. This paper aims to review the most recent innovations in the field of nutritional status and food intake-related problems of VAI (both in adulthood and in childhood).

Assistance ventilatoire à domicile : justifications et contraintes physiopathologiques

INTRODUCTION

Domiciliary assisted ventilation (DAV) may be undertaken invasively or non-invasively. Non-invasive DAV is used for patients suffering from alveolar hypoventilation due to restrictive pathology. Invasive DAV is reserved for "indications of necessity" that is when non-invasive ventilation is contraindicated due to the absence of adequate cough and for alveolar hypoventilation leading to hypercapnoea during spontaneous ventilation.

STATE OF THE ART

The main pathophysiological limitation to non-invasive ventilation is the interference of the glottis. In this mode the glottis imposes a variable resistance to the ventilation delivered. Its behaviour is more predictable during Volume controlled than during pressure controlled ventilation. The control parameters of a Volume controlled ventilator are very different from those used in invasive ventilation during which the respiratory system may be regarded as a single compartment (provided a cuffed tube bypasses the upper airway). In non-invasive DAV: mode VCM, tidal volume 13 mls kg(-1), rate 20 cycles min(-1), insp/exp ratio 1/1.2. In invasive DAV: mode VCM, tidal volume 8-10 mls kg(-1), rate 12 cycles min(-1), insp/exp ratio depending on the pathology 1/2.

PERSPECTIVES

As non-invasive DAV is essentially delivered during sleep the parameters for each patient can be optimised during polysomnography because waking, leading to a partial glottic occlusion, interferes with the ventilation delivered.

CONCLUSIONS

Recent understanding of the way the glottis interferes with mechanical ventilation when delivered non-invasively should lead to a revision of earlier practices based on invasive ventilation.