Practical problems in the respiratory care of patients with muscular dystrophy

Respiratory comorbidities and treatments in Duchenne muscular dystrophy: impact on life expectancy and causes of death

BACKGROUND

Duchenne muscular dystrophy (DMD) is a neuromuscular disorder with progressive decline of pulmonary function increasing the risk of early mortality. The aim of this study was to explore the respiratory-related comorbidities, and the effect of these comorbidities and treatments on life expectancy and causes of death.

METHODS

All male patients living in Sweden with DMD, born and deceased 1970-2019, were included. Data regarding causes of death were collected from the Cause of Death Registry and cross-checked with the medical records along with diagnostics and relevant clinical features.

RESULTS

Hundred and twenty nine patients were included with a median lifespan of 24.3 years. Acute respiratory failure accounted for 63.3% of respiratory-related causes of death. 70.1% suffered at least one pneumonia, with first episode at a median age of 17.8 years. Hypoventilation was found in 73.0% with onset at 18.1 years. 60.5% had their first pneumonia before established hypoventilation. Age at onset of hypoventilation showed a strong correlation with age at first pneumonia. First pneumonia and scoliosis non-treated with scoliosis surgery increased the risk of dying of respiratory-related causes. In 10% of the patients, first pneumonia resulted in acute tracheostomy or early death. Patients treated with assisted ventilation had higher life expectancy compared to untreated patients.

CONCLUSIONS

Our results highlight the importance of identifying subclinical hypoventilation in a timely manner and the importance of an active treatment regime upon clinical signs of pneumonia.

Long-term Observation in Patients with Duchenne Muscular Dystrophy with Early Introduction of a Standing Program Using Knee-ankle-foot Orthoses

Objectives

This study investigated the outcomes of the early introduction of a standing program for patients with Duchenne muscular dystrophy (DMD).

Methods

This was a retrospective observational study of 41 outpatients with DMD aged 15-20 years. We introduced the standing program using knee-ankle-foot orthoses (KAFO) to slow the progression of scoliosis when ankle dorsiflexion became less than 0° in the ambulatory period.

Results

Thirty-two patients with DMD were offered the standing program with KAFO; 12 continued the program until the age of 15 years (complete group) and 20 discontinued the program before the age of 15 years (incomplete group). The non-standing program group included 9 patients. The standing program with KAFO was significantly associated with the Cobb angle at the age of 15 years after adjustment for the duration of corticosteroid use and DMD mutation type (P=0.0004). At the age of 15 years, significant correlations were found between the ankle dorsiflexion range of motion (ROM) and non-ambulatory period (P=0.0010), non-ambulatory period and Cobb angle (P<0.0001), Cobb angle and percent predicted forced vital capacity (P=0.0004), and ankle dorsiflexion ROM and Cobb angle (P=0.0066). In the complete group, the age at ambulation loss (log-rank P=0.0015), scoliosis progression (log-rank P=0.0032), and pulmonary dysfunction (log-rank P=0.0006) were significantly higher than in the non-standing program group.

Conclusions

The early introduction of a standing program for DMD patients may prolong the ambulation period and slow the progression of scoliosis and pulmonary dysfunction.

Erratum: Spontaneous transverse colon volvulus in a patient with Duchenne muscular dystrophy: An unreported complication

[This corrects the article DOI: 10.1016/j.radcr.2022.12.062.][This corrects the article DOI: 10.1016/j.radcr.2023.03.026.].

Spontaneous transverse colon volvulus in a patient with Duchenne muscular dystrophy: An unreported complication

A 22-year-old male patient with Duchenne muscular dystrophy (DMD) and chronic constipation presents to the emergency room with severe abdominal pain and hive closed to feces and gas. Contrast-enhanced computed tomography of the abdomen demonstrates mechanical ileus due to volvulus of the transverse colon: torsion of the transverse mesocolon is confirmed and subtotaly colectomy is performed, revealing multiple ischemic areas with focal perforations. DMD is frequently associated with gastrointestinal motility disorders, including chronic constipation and life-threatening conditions like intestinal pseudo-obstruction and sigmoid volvulus. To date, transverse colic localization of volvolus represents an unreported condition among patients with DMD.

Pulmonary function testing in neuromuscular disease

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

Diagnosis and treatment of pneumonia, a common cause of respiratory failure in patients with neuromuscular disorders

Patients with neuromuscular diseases, during their illness are more susceptible to respiratory infections due to predisposing factors. Ineffective cough and the presence of atelectasis and hypoventilation, dysphagia and drooling can represent risk factors for the development of respiratory infection and fatal respiratory failure.

Infections of respiratory tract with acute respiratory failure are the most common reason for hospitalizations, and pneumonia is among the leading causes of morbidity and mortality worldwide. The setting in which pneumonia is acquired heavily influences diagnostic and therapeutic choices. We will focus on aetiopathogenesis, diagnosis and treatment of pneumonia in these subjects, particularly considering the disease severity, rates of antibiotic resistance and the possible complications. In this case consultations with specialized physicians are strongly recommended.

Evaluating the Diagnostic and Prognostic Value of Biomarkers for Heart Disease and Major Adverse Cardiac Events in Patients With Muscular Dystrophy

AIMS

Heart disease is recognized as the leading cause of morbidity and mortality in patients with muscular dystrophy (MD). Our study demonstrates the clinical utility of cardiac biomarkers to improve the diagnosis of cardiomyopathy and prognostication of major adverse cardiac events (MACE) in these vulnerable patients.

METHODS AND RESULTS

We prospectively followed 117 patients (median age, 42 (interquartile range [IQR], 26-50) years; 49 [41.9%] women) at the Neuromuscular Multidisciplinary clinic diagnosed with a dystrophinopathy, limb-girdle MD, type 1 myotonic dystrophy, or facioscapulohumeral MD. We determined that B-type natriuretic peptide (BNP) and high-sensitive troponin I (hsTnI) were effective diagnostic markers of cardiomyopathy (area under the curve [AUC], 0.64; P=0.017; and AUC, 0.69; P=0.001, respectively). Patient risk stratification for MACE was based on cutoff values of BNP and hsTnI defined a priori as 30.5000 pg/mL and 7.6050 ng/L, respectively. Over a median follow-up period of 2.09 (IQR, 1.17-2.81) years there were 36 confirmed MACE. Multivariate regression analyses showed that patients with BNP and hsTnI levels above the respective cutoff values had a 3.70-fold (P=0.001) and 3.24-fold (P=0.002) greater risk of MACE, respectively, compared to patients with biomarker levels below. Furthermore, patients with biomarker levels above both cutoff values had a 4.08-fold (P=0.001) greater risk of MACE. Inflammatory biomarkers did not show clinical utility for heart disease in these patients.

CONCLUSION

Our study demonstrates important diagnostic and prognostic value of BNP and hsTnI as part of a comprehensive cardiac assessment to augment the management and treatment of heart disease in patients with MD.

Spinal cord injury and diaphragm neuromotor control

Introduction: Neuromotor control of diaphragm muscle and the recovery of diaphragm activity following spinal cord injury have been narrowly focused on ventilation. By contrast, the understanding of neuromotor control for non-ventilatory expulsive/straining maneuvers (including coughing, defecation, and parturition) is relatively impoverished. This variety of behaviors are achieved via the recruitment of the diverse array of motor units that comprise the diaphragm muscle.Areas covered: The neuromotor control of ventilatory and non-ventilatory behaviors in health and in the context of spinal cord injury is explored. Particular attention is played to the neuroplasticity of phrenic motor neurons in various models of cervical spinal cord injury.Expert opinion: There is a remarkable paucity in our understanding of neuromotor control of maneuvers in spinal cord injury patients. Dysfunction of these expulsive/straining maneuvers reduces patient quality of life and contributes to severe morbidity and mortality. As spinal cord injury patient life expectancies continue to climb steadily, a nexus of spinal cord injury and age-associated comorbidities are likely to occur. While current research remains concerned only with the minutiae of ventilation, the major functional deficits of this clinical cohort will persist intractably. We posit some future research directions to avoid this scenario.

Timed immersion expiration measures in patients with muscular dystrophies

Introduction

Muscular dystrophies (MD) cause muscle weakness, affecting motor and respiratory functions. Aquatic activities maintain strength and ventilatory function and may require immersion expiration control.

Objectives

(1) To describe the evolution of timed immersion expiration in patients with MD in one-year follow-up. (2) to describe motor and respiratory outcomes in one-year follow-up. (3) to investigate possible relationships between timed immersion expiration and age, motor and respiratory functions.

Method

Fifty-seven patients with MD (12-35 years, Vignos scale 2-8) were evaluated twice, with one-year interval. Immersion expiration control was timed with a chronometer. Motor function was assessed by Motor Function Measure. The respiratory function was evaluated by spirometry. Analysis of variance compared assessments and Pearson tests investigated relationships between variables and age.

Results

Motor and respiratory functions decreased (p < 0.001) but timed immersion expiration was maintained. Timed immersion expiration was not correlated to motor and respiratory functions.

Conclusion

As patients maintained timed immersion expiration in the one-year follow-up, aquatic therapy might be a facilitator for people with MD.

Cardiac Intervention Improves Heart Disease and Clinical Outcomes in Patients With Muscular Dystrophy in a Multidisciplinary Care Setting

Background

Patients with muscular dystrophy (MD) represent a vulnerable patient population with no clearly defined care model in modern‐day clinical practice to manage a high burden of heart disease and comorbidities. We demonstrate the effectiveness of cardiac interventions, namely the initiation and optimization of medical and device therapies, as part of a multidisciplinary care approach to improve clinical outcomes in patients with MD.

Methods and Results

We conducted a prospective cohort study at the Neuromuscular Multidisciplinary clinic following patients with dystrophinopathies, limb‐girdle MD, type 1 myotonic dystrophy, and facioscapulohumeral MD. A negative control group classified as non‐MD myopathies without heart disease, was also tracked. Our cohort of 185 patients (median age: 42 years; 79 [42.7%] women), included 145 patients with MD. Cardiomyopathy was present in 65.6% of the patients with dystrophinopathies (21 of 32) and 27.3% of the patients with limb‐girdle MD (9 of 33). Conduction abnormalities were common in type 1 myotonic dystrophy (33.3% [20/60] patients). Cardiac intervention reversed systolic dysfunction, with left ventricular ejection fraction improving from 43% to 50.0% over a 3‐year period. A sustained reduction in healthcare utilization was also observed. The number of outpatient clinic visits decreased from 3.0 to 1.5 visits per year, the duration of hospitalizations was reduced from 14.2 to 0.9 days per year, and the number of cardiac‐related hospitalizations decreased from 0.4 to 0.1 hospitalizations per year associated with low mortality.

Conclusions

Our study demonstrates that cardiac intervention as part of a comprehensive multidisciplinary care approach to treating patients with MD leads to a sustained improvement in clinical outcomes.

Echographic Assessment of Diaphragmatic Function in Duchenne Muscular Dystrophy from Childhood to Adulthood

BACKGROUND

Duchenne muscular dystrophy (DMD) is an X-linked recessive genetic muscle disorder. Respiratory muscle function is classically affected in this disease. Ultrasound recently emerged as a non-invasive tool to assess diaphragm function. However, there are only a few studies using diaphragm ultrasound (US) in DMD.

PURPOSE

We aimed to assess diaphragm ultrasound patterns in DMD, their relationship with age and their association with home mechanical ventilation (HMV).

METHODS

We included DMD patients followed at Raymond Poincaré Hospital who benefited from diaphragm ultrasound and pulmonary function tests.

RESULTS

There were 110 DMD patients and 17 male sex-matched healthy subjects included. In all, 94% of patients were permanent wheelchair users. Median body mass index (BMI) was 18 kg/m2. DMD patients disclosed a reduced forced vital capacity (VC) (12% of predicted value), and 78% of patients were on HMV. In patients, right and left diaphragmatic motions on deep inspiration were reduced and end expiratory diaphragm thickness was borderline normal. In patients, right and left diaphragmatic thickening fractions (TF) were reduced 12.7% and 15.5%, respectively. Age and end expiratory thickness were significantly inversely associated (p = 0.005 for the right diaphragm, p = 0.018 for the left diaphragm). Diaphragm TF was significantly inversely associated with age (p = 0.001 for the right side, p < 0.0001 for the left side). Right and left inspiratory diaphragm motions were significantly inversely associated with age (p < 0.0001).

CONCLUSION

This study describes the severity of diaphragm dysfunction in patients with DMD. Diaphragm US may be a non-invasive outcome measure for DMD.

Longitudinal changes in clinical outcome measures in COL6-related dystrophies and LAMA2-related dystrophies

OBJECTIVE

To identify the rate of change of clinical outcome measures in children with 2 types of congenital muscular dystrophy (CMD), COL6-related dystrophies (COL6-RDs) and LAMA2-related dystrophies (LAMA2-RDs).

METHODS

Over the course of 4 years, 47 individuals (23 with COL6-RD and 24 with LAMA2-RD) 4 to 22 years of age were evaluated. Assessments included the Motor Function Measure 32 (MFM32), myometry (knee flexors and extensors, elbow flexors and extensors), goniometry (knee and elbow extension), pulmonary function tests, and quality-of-life measures. Separate linear mixed-effects models were fitted for each outcome measurement, with subject-specific random intercepts.

RESULTS

Total MFM32 scores for COL6-RDs and LAMA2-RDs decreased at a rate of 4.01 and 2.60 points, respectively, each year (p < 0.01). All muscle groups except elbow flexors for individuals with COL6-RDs decreased in strength between 1.70% (p < 0.05) and 2.55% (p < 0.01). Range-of-motion measurements decreased by 3.21° (p < 0.05) at the left elbow each year in individuals with LAMA2-RDs and 2.35° (p < 0.01) in right knee extension each year in individuals with COL6-RDs. Pulmonary function demonstrated a yearly decline in sitting forced vital capacity percent predicted of 3.03% (p < 0.01) in individuals with COL6-RDs. There was no significant change in quality-of-life measures analyzed.

CONCLUSION

Results of this study describe the rate of change of motor function as measured by the MFM32, muscle strength, range of motion, and pulmonary function in individuals with COL6-RDs and LAMA2-RDs.

Pulmonary Function Testing in Neuromuscular and Chest Wall Disorders

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

Comparison of sitting and supine forced vital capacity in collagen VI-related dystrophy and laminin α2-related dystrophy

BACKGROUND

Progressive, restrictive, respiratory insufficiency is the major cause of morbidity and mortality in Congenital Muscular Dystrophy (CMD). Nocturnal hypoventilation precedes daytime alveolar hypoventilation, and if untreated, may lead to respiratory failure and cor pulmonale. CMD consensus care guidelines recommend screening for respiratory insufficiency by conventional and dynamic (sitting to supine) pulmonary function testing (PFT) and evaluating for sleep disordered breathing if there is more than 20% relative reduction from sitting to supine FVC(L) (ΔFVC).

OBJECTIVE

The objective of this retrospective study was to explore and characterize dynamic FVC measures in 51 individuals with two common subtypes of CMD, COL6-RD, and LAMA2-RD.

METHODS

We compared sitting and supine FVC in patients with confirmed mutation(s) in either COL6 or LAMA2. We investigated influences of age, CMD subtype, gender, race, ambulatory status, and non-invasive positive pressure ventilation (NIPPV) status on FVC percent predicted (FVCpp) and ΔFVC.

RESULTS

COL6-RD participants exhibited a significant difference between sitting and supine mean FVCpp (sitting 66.1, supine 55.1; P < 0.0001) and were 5.4 times more likely to have -ΔFVC >20% than those with LAMA2-RD when controlling for ambulant status. FVCpp sitting correlated inversely with age in individuals ≤18 years.

CONCLUSION

FVCpp sitting decreases progressively in childhood in both CMD subtypes. However, our results point to a difference in diaphragmatic involvement, with COL6-RD individuals having more disproportionate diaphragmatic weakness than LAMA2-RD. A ΔFVC of greater than -20% should continue to be used to prompt evaluation of sleep-disordered breathing. Timely initiation of NIPPV may be indicated to treat nocturnal hypoventilation. Pediatr Pulmonol. 2017;52:524-532. © 2017 Wiley Periodicals, Inc.

Treatment effect of idebenone on inspiratory function in patients with Duchenne muscular dystrophy

Assessment of dynamic inspiratory function may provide valuable information about the degree and progression of pulmonary involvement in patients with Duchenne muscular dystrophy (DMD). The aims of this study were to characterize inspiratory function and to assess the efficacy of idebenone on this pulmonary function outcome in a large and well-characterized cohort of 10-18 year-old DMD patients not taking glucocorticoid steroids (GCs) enrolled in the phase 3 randomized controlled DELOS trial. We evaluated the effect of idebenone on the highest flow generated during an inspiratory FVC maneuver (maximum inspiratory flow; V'I,max(FVC)) and the ratio between the largest inspiratory flow during tidal breathing (tidal inspiratory flow; V'I,max(t)) and the V'I,max(FVC). The fraction of the maximum flow that is not used during tidal breathing has been termed inspiratory flow reserve (IFR). DMD patients in both treatment groups of DELOS (idebenone, n = 31; placebo: n = 33) had comparable and abnormally low V'I,max(FVC) at baseline. During the study period, V'I,max(FVC) further declined by -0.29 L/sec in patients on placebo (95%CI: -0.51, -0.08; P = 0.008 at week 52), whereas it remained stable in patients on idebenone (change from baseline to week 52: 0.01 L/sec; 95%CI: -0.22, 0.24; P = 0.950). The between-group difference favoring idebenone was 0.27 L/sec (P = 0.043) at week 26 and 0.30 L/sec (P = 0.061) at week 52. In addition, during the study period, IFR improved by 2.8% in patients receiving idebenone and worsened by -3.0% among patients on placebo (between-group difference 5.8% at week 52; P = 0.040). Although the clinical interpretation of these data is currently limited due to the scarcity of routine clinical practice experience with dynamic inspiratory function outcomes in DMD, these findings from a randomized controlled study nevertheless suggest that idebenone preserved inspiratory muscle function as assessed by V'I,max(FVC) and IFR in patients with DMD. Pediatr Pulmonol. 2017;52:508-515. © 2016 The Authors. Pediatric Pulmonology Published by Wiley Periodicals, Inc.

Short-term effect of volume recruitment-derecruitment manoeuvre on chest-wall motion in Duchenne muscular dystrophy

Because progressive respiratory muscle weakness leads to decreased chest-wall motion with eventual ribcage stiffening, the purpose was to compare vital capacity (VC) and contributions of chest-wall compartments before and after volume recruitment-derecruitment manoeuvres (VRDM) in Duchenne muscular dystrophy (DMD). We studied nine patients with DMD and VC lower than 30% of predicted. VRDM was performed using 15 insufflations-exsufflations of +30 to -30 cmH₂O. VC and three-dimensional chest-wall motion were measured, as well as oxygen saturation, transcutaneous partial pressure of carbon dioxide and the rapid shallow breathing index (respiratory rate/tidal volume) before (baseline) and immediately and 1 hour after VRDM. VC increased significantly immediately after VRDM (108% ± 7% of baseline, p = 0.018) but returned to baseline within 1 hour, and the rapid shallow breathing index increased significantly. The non-dominant side systematically increased immediately after VRDM ( p = 0.0077), and in the six patients with abnormal breathing asymmetry (difference >10% of VC) at baseline, this asymmetry was corrected immediately and/or 1 hour after VRDM. VRDM improved VC and reduced chest-wall motion asymmetry, but this beneficial effect waned rapidly with respiratory muscle fatigue, suggesting that VRDM may need to be repeated during the day to produce lasting benefits.

Affection of the Respiratory Muscles in Combined Complex I and IV Deficiency

Objectives:

Combined complex I+IV deficiency has rarely been reported to manifest with the involvement of the respiratory muscles.

Case Report:

A 45y male was admitted for hypercapnia due to muscular respiratory insufficiency. He required intubation and mechanical ventilation. He had a previous history of ophthalmoparesis since age 6y, ptosis since age 23y, and anterocollis since at least age 40y. Muscle biopsy from the right deltoid muscle at age 41y was indicative of mitochondrial myopathy. Biochemical investigations revealed a combined complex I+IV defect. Respiratory insufficiency was attributed to mitochondrial myopathy affecting not only the extra-ocular and the axial muscles but also the shoulder girdle and respiratory muscles. In addition to myopathy, he had mitochondrial neuropathy, abnormal EEG, and elevated CSF-protein. Possibly, this is why a single cycle of immunoglobulins was somehow beneficial. For muscular respiratory insufficiency he required tracheostomy and was scheduled for long-term intermittent positive pressure ventilation.

Conclusion:

Mitochondrial myopathy due to a combined complex I+IV defect with predominant affection of the extra-ocular muscles may progress to involvement of the limb-girdle, axial and respiratory muscles resulting in muscular respiratory insufficiency. In patients with mitochondrial myopathy, neuropathy and elevated cerebrospinal fluid protein, immunoglobulins may be beneficial even for respiratory functions.

Gastrointestinal Dysfunction in Patients with Duchenne Muscular Dystrophy

Background

In adult patients with Duchenne muscular dystrophy (DMD) life-threatening constipation has been reported. Since gastrointestinal function in DMD has not been rigorously studied we investigated objective and subjective manifestations of gastrointestinal disturbances in DMD patients.

Methods

In 33 patients with DMD, age 12–41 years, eating behavior and gastrointestinal symptoms were evaluated by questionnaires. Gastric emptying half time (T_1/2) and oro-cecal transit time (OCTT) were evaluated by analyzing ¹³CO₂ exhalation curves after ingestion of ¹³C labeled test meals. Colonic transit time (CTT) was measured by abdominal radiography following ingestion of radiopaque markers.

Results

The median (quartiles) T_1/2 was 187 (168, 220) minutes, the OCTT was 6.3 (5.0, 7.9) hours, both substantially longer than normal data (Goetze 2005, T_1/2: 107±10; Geypens 1999, OCTT 4.3±0.1 hours). The median CTT was 60 (48, 82) hours despite extensive use of laxative measures (Meier 1995, upper limit of normal: 60 hours). T_1/2 and OCTT did not correlate with symptoms evaluated by the Gastroparesis Cardinal Symptom Index (GCSI) (Spearman r = -0.3, p = 0.1; and r = -0.15, p = 0.4, respectively). CTT was not correlated with symptoms of constipation assessed by ROME III criteria (r = 0.12, p = 0.5).

Conclusions

DMD patients have a markedly disturbed gastrointestinal motor function. Since objective measures of impaired gastrointestinal transport are not correlated with symptoms of gastroparesis or constipation our findings suggest that measures assuring adequate intestinal transport should be taken independent of the patient’s perception in order to prevent potentially life threatening constipation, particularly in older DMD patients.

Neurologic Causes of Acute Respiratory Dysfunction

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

Management of Ventilatory Insufficiency in Neuromuscular Patients Using Mechanical Ventilator Supported by the Korean Government

Since 2001, financial support has been provided for all patients with neuromuscular disease (NMD) who require ventilatory support due to the paralysis of respiratory muscles in Korea. The purpose of this study was to identify ventilator usage status and appropriateness in these patients. We included 992 subjects with rare and incurable NMD registered for ventilator rental fee support. From 21 February 2011 to 17 January 2013, ventilator usage information, regular follow-up observation, and symptoms of chronic hypoventilation were surveyed by phone. Home visits were conducted for patients judged by an expert medical team to require medical examination. Abnormal ventilatory status was assessed by respiratory evaluation. Chronic respiratory insufficiency symptoms were reported by 169 of 992 subjects (17%), while 565 subjects (57%) did not receive regular respiratory evaluation. Ventilatory status was abnormal in 102 of 343 home-visit subjects (29.7%). Although 556 subjects (56%) reported 24-hour ventilator use, only 458 (46%) had an oxygen saturation monitoring device, and 305 (31%) performed an airstacking exercise. A management system that integrates ventilator usage monitoring, counselling and advice, and home visits for patients who receive ventilator support could improve the efficiency of the ventilator support project.

Idebenone reduces respiratory complications in patients with Duchenne muscular dystrophy

In Duchenne muscular dystrophy (DMD), progressive loss of respiratory function leads to restrictive pulmonary disease and places patients at significant risk for severe respiratory complications. Of particular concern are ineffective cough, secretion retention and recurrent respiratory tract infections. In a Phase 3 randomized controlled study (DMD Long-term Idebenone Study, DELOS) in DMD patients 10-18 years of age and not taking concomitant glucocorticoid steroids, idebenone (900 mg/day) reduced significantly the loss of respiratory function over a 1-year study period. In a post-hoc analysis of DELOS we found that more patients in the placebo group compared to the idebenone group experienced bronchopulmonary adverse events (BAEs): placebo: 17 of 33 patients, 28 events; idebenone: 6 of 31 patients, 7 events. The hazard ratios (HR) calculated "by patient" (HR 0.33, p = 0.0187) and for "all BAEs" (HR 0.28, p = 0.0026) indicated a clear idebenone treatment effect. The overall duration of BAEs was 222 days (placebo) vs. 82 days (idebenone). In addition, there was also a difference in the use of systemic antibiotics utilized for the treatment of BAEs. In the placebo group, 13 patients (39.4%) reported 17 episodes of antibiotic use compared to 7 patients (22.6%) reporting 8 episodes of antibiotic use in the idebenone group. Furthermore, patients in the placebo group used systemic antibiotics for longer (105 days) compared to patients in the idebenone group (65 days). This post-hoc analysis of DELOS indicates that the protective effect of idebenone on respiratory function is associated with a reduced risk of bronchopulmonary complications and a reduced need for systemic antibiotics.

Can daytime measures of lung function predict respiratory failure in children with neuromuscular disease?

Neuromuscular disorders in children are a heterogeneous group of conditions with a variable age of presentation and overlapping clinical manifestations, many of which have progressive respiratory morbidity. Respiratory insufficiency occurs as a consequence of an imbalance between demands on the respiratory system and respiratory muscle capacity. Daytime measures of pulmonary function are used routinely in these children to assess respiratory status and monitor the consequences of the progression of muscle weakness. This review describes the current evidence for daytime pulmonary function tests and their ability to predict imminent respiratory morbidity.

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 commonly used to treat it. This is a 2014 update of a review first published in 2000 and previously updated in 2007.

OBJECTIVES

To examine the effects on mortality of nocturnal mechanical ventilation in people with neuromuscular or chest wall disorders. Subsidiary endpoints were to examine the effects of respiratory assistance on improvement of chronic hypoventilation, sleep quality, hospital admissions and quality of life.

SEARCH METHODS

We searched the Cochrane Neuromuscular Disease Group Specialized Register, CENTRAL, MEDLINE and EMBASE on 10 June 2014. We contacted authors of identified trials and other experts in the field.

SELECTION CRITERIA

We searched for quasi-randomised or randomised controlled trials of participants of all ages with neuromuscular or chest wall disorder-related stable chronic hypoventilation of all degrees of severity, receiving any type and any mode of long-term nocturnal mechanical ventilation. The primary outcome measure was one-year mortality and secondary outcomes were unplanned hospital admission, short-term and long-term reversal of hypoventilation-related clinical symptoms and daytime hypercapnia, improvement of lung function and sleep breathing disorders.

DATA COLLECTION AND ANALYSIS

We used standard Cochrane methodology to select studies, extract data and assess the risk of bias in included studies.

MAIN RESULTS

The 10 eligible trials included a total of 173 participants. Roughly half of the trials were at low risk of selection, attrition or reporting bias, and almost all were at high risk of performance and detection bias. Four trials reported mortality data in the long term. The pooled risk ratio (RR) of dying was 0.62 (95% confidence interval (CI) 0.42 to 0.91, P value = 0.01) in favour of nocturnal mechanical ventilation compared to spontaneous breathing. There was considerable and significant heterogeneity between the trials, possibly related to differences between the study populations. Information on unplanned hospitalisation was available from two studies. The corresponding pooled RR was 0.25 (95% CI 0.08 to 0.82, P value = 0.02) in favour of nocturnal mechanical ventilation. For most of the outcome measures there was no significant long-term difference between nocturnal mechanical ventilation and no ventilation. Most of the secondary outcomes were not assessed in the eligible trials. Three out of the 10 trials, accounting for 39 participants, two with a cross-over design and one with two parallel groups, compared volume- and pressure-cycled non-invasive mechanical ventilation in the short term. From the only trial (16 participants) on parallel groups, there was no difference in mortality (one death in each arm) between volume- and pressure-cycled mechanical ventilation. Data from the two cross-over trials suggested that compared with pressure-cycled ventilation, volume-cycled ventilation was associated with less sleep time spent with an arterial oxygen saturation below 90% (mean difference (MD) 6.83 minutes, 95% CI 4.68 to 8.98, P value = 0.00001) and a lower apnoea-hypopnoea (per sleep hour) index (MD -0.65, 95% CI -0.84 to -0.46, P value = 0.00001). We found no study that compared invasive and non-invasive mechanical ventilation or intermittent positive pressure versus negative pressure ventilation.

AUTHORS' CONCLUSIONS

Current evidence about the therapeutic benefit of mechanical ventilation is of very low quality, but is consistent, suggesting alleviation of the symptoms of chronic hypoventilation in the short term. In four small studies, survival was prolonged and unplanned hospitalisation was reduced, mainly in participants with motor neuron diseases. With the exception of motor neuron disease and Duchenne muscular dystrophy, for which the natural history supports the survival benefit of mechanical ventilation against no ventilation, further larger randomised trials should assess the long-term benefit of different types and modes of nocturnal mechanical ventilation on quality of life, morbidity and mortality, and its cost-benefit ratio in neuromuscular and chest wall diseases.

Systematic Analysis of the Multiple Bioactivities of Green Tea through a Network Pharmacology Approach

During the past decades, a number of studies have demonstrated multiple beneficial health effects of green tea. Polyphenolics are the most biologically active components of green tea. Many targets can be targeted or affected by polyphenolics. In this study, we excavated all of the targets of green tea polyphenolics (GTPs) though literature mining and target calculation and analyzed the multiple pharmacology actions of green tea comprehensively through a network pharmacology approach. In the end, a total of 200 Homo sapiens targets were identified for fifteen GTPs. These targets were classified into six groups according to their related disease, which included cancer, diabetes, neurodegenerative disease, cardiovascular disease, muscular disease, and inflammation. Moreover, these targets mapped into 143 KEGG pathways, 26 of which were more enriched, as determined though pathway enrichment analysis and target-pathway network analysis. Among the identified pathways, 20 pathways were selected for analyzing the mechanisms of green tea in these diseases. Overall, this study systematically illustrated the mechanisms of the pleiotropic activity of green tea by analyzing the corresponding “drug-target-pathway-disease” interaction network.

Relation between hand grip strength, respiratory muscle strength and spirometric measures in male nursing home residents

Adverse-outcomes related to sarcopenia are mostly mentioned as physical disability. As the other skeletal muscles, respiratory muscles may also be affected by sarcopenia. Respiratory muscle strength is known to affect pulmonary functions. Therefore, we aimed to investigate the relations between extremity muscle strength, respiratory muscle strengths and spirometric measures in a group of male nursing home residents. Among a total of 104 male residents, residents with obstructive measures were excluded and final study population was composed of 62 residents. Mean age was 70.5 ± 6.7 years, body mass index: 27.7 ± 5.3 kg/m2 and dominant hand grip strength: 29.7 ± 6.5 kg. Hand grip strength was positively correlated with maximal inspiratory pressure (MIP) and maximal expiratory pressure (MEP) (r = 0.35, p < 0.01 and r = 0.26, p < 0.05, respectively). In regression analysis, the only factor related to MIP was hand grip strength; among spirometric measures only parameter significantly related to grip strength was peak cough flow (PCF). The association of PCF with grip strength disappeared when MIP alone or "MIP and MEP" were included in the regression analysis. In the latter case, PCF was significantly associated only with MIP. We found peripheric muscle strength be associated with MIP and PCF but not with MEP or any other spirometric parameters. The relation between peripheral muscle strength and PCF was mediated by MIP. Our findings suggest that sarcopenia may affect inspiratory muscle strength earlier or more than the expiratory muscle strength. Sarcopenia may cause decrease in PCF in the elderly, which may stand for some common adverse respiratory complications.

Natural history of pulmonary function in collagen VI-related myopathies

The spectrum of clinical phenotypes associated with a deficiency or dysfunction of collagen VI in the extracellular matrix of muscle are collectively termed 'collagen VI-related myopathies' and include Ullrich congenital muscular dystrophy, Bethlem myopathy and intermediate phenotypes. To further define the clinical course of these variants, we studied the natural history of pulmonary function in correlation to motor abilities in the collagen VI-related myopathies by analysing longitudinal forced vital capacity data in a large international cohort. Retrospective chart reviews of genetically and/or pathologically confirmed collagen VI-related myopathy patients were performed at 10 neuromuscular centres: USA (n = 2), UK (n = 2), Australia (n = 2), Italy (n = 2), France (n = 1) and Belgium (n = 1). A total of 486 forced vital capacity measurements obtained in 145 patients were available for analysis. Patients at the severe end of the clinical spectrum, conforming to the original description of Ullrich congenital muscular dystrophy were easily identified by severe muscle weakness either preventing ambulation or resulting in an early loss of ambulation, and demonstrated a cumulative decline in forced vital capacity of 2.6% per year (P < 0.0001). Patients with better functional abilities, in whom walking with/without assistance was achieved, were initially combined, containing both intermediate and Bethlem myopathy phenotypes in one group. However, one subset of patients demonstrated a continuous decline in pulmonary function whereas the other had stable pulmonary function. None of the patients with declining pulmonary function attained the ability to hop or run; these patients were categorized as intermediate collagen VI-related myopathy and the remaining patients as Bethlem myopathy. Intermediate patients had a cumulative decline in forced vital capacity of 2.3% per year (P < 0.0001) whereas the relationship between age and forced vital capacity in patients with Bethlem myopathy was not significant (P = 0.1432). Nocturnal non-invasive ventilation was initiated in patients with Ullrich congenital muscular dystrophy by 11.3 years (±4.0) and in patients with intermediate collagen VI-related myopathy by 20.7 years (±1.5). The relationship between maximal motor ability and forced vital capacity was highly significant (P < 0.0001). This study demonstrates that pulmonary function profiles can be used in combination with motor function profiles to stratify collagen VI-related myopathy patients phenotypically. These findings improve our knowledge of the natural history of the collagen VI-related myopathies, enabling proactive optimization of care and preparing this patient population for clinical trials.

Conditional expression of TGF-β1 in skeletal muscles causes endomysial fibrosis and myofibers atrophy

To study the effects of transforming growth factor beta 1 (TGF-β1) on fibrosis and failure of regeneration of skeletal muscles, we generated a tet-repressible muscle-specific TGF-β1 transgenic mouse in which expression of TGF-β1 is controlled by oral doxycycline. The mice developed muscle weakness and atrophy after TGF-β1 over-expression. We defined the group of mice that showed phenotype within 2 weeks as early onset (EO) and the rest as late onset (LO), which allowed us to further examine phenotypic differences between the groups. While only mice in the EO group showed significant muscle weakness, pathological changes including endomysial fibrosis and smaller myofibers were observed in both groups at two weeks after the TGF-β1 was over-expressed. In addition, the size of the myofibers and collagen accumulation were significantly different between the two groups. The amount of latent and active TGF-β1 in the muscle and circulation were significantly higher in the EO group compared to the LO or control groups. The up-regulation of the latent TGF-β1 indicated that endogenous TGF-β1 was induced by the expression of the TGF-β1 transgene. Our studies showed that the primary effects of TGF-β1 over-expression in skeletal muscles are muscle wasting and endomysial fibrosis. In addition, the severity of the pathology is associated with the total amount of TGF-β1 and the expression of endogenous TGF-β1. The findings suggest that an auto-feedback loop of TGF-β1 may contribute to the severity of phenotypes.

Ventilatory chemosensory drive is blunted in the mdx mouse model of Duchenne Muscular Dystrophy (DMD)

Duchenne Muscular Dystrophy (DMD) is caused by mutations in the DMD gene resulting in an absence of dystrophin in neurons and muscle. Respiratory failure is the most common cause of mortality and previous studies have largely concentrated on diaphragmatic muscle necrosis and respiratory failure component. Here, we investigated the integrity of respiratory control mechanisms in the mdx mouse model of DMD. Whole body plethysmograph in parallel with phrenic nerve activity recordings revealed a lower respiratory rate and minute ventilation during normoxia and a blunting of the hypoxic ventilatory reflex in response to mild levels of hypoxia together with a poor performance on a hypoxic stress test in mdx mice. Arterial blood gas analysis revealed low PaO2 and pH and high PaCO2 in mdx mice. To investigate chemosensory respiratory drive, we analyzed the carotid body by molecular and functional means. Dystrophin mRNA and protein was expressed in normal mice carotid bodies however, they are absent in mdx mice. Functional analysis revealed abnormalities in Dejours test and the early component of the hypercapnic ventilatory reflex in mdx mice. Together, these results demonstrate a malfunction in the peripheral chemosensory drive that would be predicted to contribute to the respiratory failure in mdx mice. These data suggest that investigating and monitoring peripheral chemosensory drive function may be useful for improving the management of DMD patients with respiratory failure.

Ventilatory control in ALS

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

Cardiac and respiratory dysfunction in Duchenne muscular dystrophy and the role of second messengers

Duchenne muscular dystrophy (DMD) affects young boys and is characterized by the absence of dystrophin, a large cytoskeletal protein present in skeletal and cardiac muscle cells and neurons. The heart and diaphragm become necrotic in DMD patients and animal models of DMD, resulting in cardiorespiratory failure as the leading cause of death. The major consequences of the absence of dystrophin are high levels of intracellular Ca(2+) and the unbalanced production of NO that can finally trigger protein degradation and cell death. Cytoplasmic increase in Ca(2+) concentration directly and indirectly triggers different processes such as necrosis, fibrosis, and activation of macrophages. The absence of the neuronal isoform of nitric oxide synthase (nNOS) and the overproduction of NO by the inducible isoform (iNOS) further increase the intracellular Ca(2+) via a hypernitrosylation of the ryanodine receptor. NO overproduction, which further induces the expression of iNOS but decreases the expression of the endothelial isoform (eNOS), deregulates the muscle tissue blood flow creating an ischemic situation. The high levels of Ca(2+) in dystrophic muscles and the ischemic state of the muscle tissue would culminate in a positive feedback loop. While efforts continue toward optimizing cardiac and respiratory care of DMD patients, both Ca(2+) and NO in cardiac and respiratory muscle pathways have been shown to be important to the etiology of the disease. Understanding the mechanisms behind the fine regulation of Ca(2+) -NO may be important for a noninterventional and noninvasive supportive approach to treat DMD patients, improving the quality of life and natural history of DMD patients.

Exercise in neuromuscular diseases

This article reviews the current knowledge regarding the benefits and contraindications of exercise on individuals with neuromuscular diseases (NMDs). Specific exercise prescriptions for individuals with NMDs do not exist because the evidence base is limited. Understanding the effect of exercise on individuals with NMDs requires the implementation of a series of multicenter, randomized controlled trials that are sufficiently powered and use reliable and valid outcome measures to assess the effect of exercise interventions-a major effort for each NMD. In addition to traditional measures of exercise efficacy, outcome variables should include measures of functional status and health-related quality of life.

Lung function monitoring in patients with duchenne muscular dystrophy on steroid therapy

BACKGROUND

Duchenne muscular dystrophy (DMD) is a sex-linked inherited muscle disease characterized by a progressive loss in muscle strength and respiratory muscle involvement. After 12 years of age, lung function declines at a rate of 6 % to 10.7 % per year in patients with DMD. Steroid therapy has been proposed to delay the loss of motor function and also the respiratory involvement.

METHOD

In 21 patients with DMD aged between seven and 16 years, the forced vital capacity (FVC) and the forced expiratory volume in one second (FEV1) were evaluated at three different times during a period of two years.

RESULTS

We observed in this period of evaluation the maintenance of the FVC and the FEV1 in this group of patients independently of chronological age, age at onset of steroid therapy, and walking capacity.

CONCLUSION

The steroid therapy has the potential to stabilize or delay the loss of lung function in DMD patients even if they are non-ambulant or older than 10 years, and in those in whom the medication was started after 7 years of age.

Nature and frequency of respiratory involvement in chronic progressive external ophthalmoplegia

Chronic progressive external ophthalmoplegia (CPEO) is a relatively common mitochondrial disorder. Weakness of the extra-ocular, limb girdle and laryngeal muscles are established clinical features. Respiratory muscle involvement however has never been studied systematically, even though respiratory complications are one of the main causes of death. We therefore determined the prevalence and nature of respiratory muscle involvement in 23 patients with genetically confirmed CPEO. The main finding was decreased respiratory muscle strength, both expiratory (76.8% of predicted, p = 0.002) and inspiratory (79.5% of predicted, p = 0.004). Although the inspiratory vital capacity (92.5% of predicted, p = 0.021) and the forced expiratory volume in 1 s (89.3% of predicted, p = 0.002) were below predicted values, both were still within the normal range in the majority of patients. Expiratory weakness was associated with a decreased vital capacity (ρ = 0.502, p = 0.015) and decreased peak expiratory flow (ρ = 0.422, p = 0.045). Moreover, expiratory muscle strength was lower in patients with limb girdle weakness (62.6 ± 26.1% of predicted vs. 98.9 ± 22.5% in patients with normal limb girdle strength, p = 0.003), but was not associated with other clinical features, subjective respiratory complaints, disease severity or disease duration. Since respiratory involvement in CPEO is associated with severe morbidity and mortality, the present data justify periodic assessment of respiratory functions in all CPEO patients.

Gene therapy with helper-dependent adenoviral vectors: current advances and future perspectives

Recombinant Adenoviral vectors represent one of the best gene transfer platforms due to their ability to efficiently transduce a wide range of quiescent and proliferating cell types from various tissues and species. The activation of an adaptive immune response against the transduced cells is one of the major drawbacks of first generation Adenovirus vectors and has been overcome by the latest generation of recombinant Adenovirus, the Helper-Dependent Adenoviral (HDAd) vectors. HDAds have innovative features including the complete absence of viral coding sequences and the ability to mediate high level transgene expression with negligible chronic toxicity. This review summarizes the many aspects of HDAd biology and structure with a major focus on in vivo gene therapy application and with an emphasis on the unsolved issues that these vectors still presents toward clinical application.

Ventilatory parameters and maximal respiratory pressure changes with age in Duchenne muscular dystrophy patients

The aim of this longitudinal study was to precise, in children with Duchenne muscular dystrophy, the respective functional interest of ventilatory parameters (Vital capacity, total lung capacity and forced expiratory volume in one second [FEV(1)]) in comparison to maximal inspiratory pressure (Pimax) during growth. In ten boys the mean age of 9.1 +/- 1 years) to mean age of 16 +/- 1.4 years followed over a period of 7 years, we found that: (1) ventilatory parameters expressed in percentage of predicted value, after a normal ascending phase, start to decrease between 11 and 12 years, (2) Pimax presented only a decreasing phase since the beginning of the study and thus was already at 67% of predicted value at 12 years while ventilatory parameters was still normal, (3) after 12 years the mean slopes of decrease per year of vital capacity and FEV1 were higher (10.7 and 10.4%) than that of Pimax (6.9%), (4) at 15 years mean values of vital capacity and FEV1 (53.3 and 49.5% of predicted values) was simlar to that of Pimax (48.3%). In conclusion, if at early stages of the disease, Pimax is a more reliable index of respiratory impaiment than ventilatory parameters, the follow-up of ventilatory parameters, when they start to decrease, is a better indicator of disease progression and, at advanced stages they provided same information about the functional impact of disease.

How respiratory muscle strength correlates with cough capacity in patients with respiratory muscle weakness

PURPOSE

The purpose of this study is to investigate how respiratory muscle strength correlates to cough capacity in patients with respiratory muscle weakness.

MATERIALS AND METHODS

Forty-five patients with amyotrophic lateral sclerosis (ALS), 43 with cervical spinal cord injury (SCI), and 42 with Duchenne muscular dystrophy (DMD) were recruited. Pulmonary function tests including forced vital capacity (FVC) and respiratory muscle strength (maximal expiratory pressure, MEP; maximal inspiratory pressure, MIP) were performed. The correlation between respiratory muscle strength and cough capacity was analyzed.

RESULTS

In the SCI group, FVC in a supine position (2,597 +/- 648 mL) was significantly higher than FVC in a sitting position (2,304 +/- 564 mL, p < 0.01). Conversely, in the ALS group, FVC sitting (1,370 +/- 604 mL) was significantly higher than in supine (1,168 +/- 599 mL, p < 0.01). In the DMD group, there was no statistically significant difference between FVC while sitting (1,342 +/- 506 mL) and FVC while supine (1,304 +/- 500 mL). In addition, the MEP and MIP of all three groups showed a significant correlation with peak cough flow (PCF) (p < 0.01, Pearson's correlation analysis). In the SCI group, MIP was more closely correlated with PCF, while in the ALS and DMD groups, MEP was more closely correlated with PCF (p < 0.01, multiple regression analysis).

CONCLUSION

To generate cough flow, inspiratory muscle strength is significantly more important for SCI patients, while expiratory muscle function is significantly more important for ALS and DMD patients.

Effects of scoliosis on respiratory muscle strength in patients with neuromuscular disorders

BACKGROUND CONTEXT

Neuromuscular disorders (NMD) are characterized by loss of lung volume and respiratory muscle weakness, but the effects of scoliosis on lung function are unclear.

PURPOSE

To compare pulmonary function and respiratory muscle strength in patients with NMD with and without scoliosis as well as in healthy controls.

STUDY DESIGN/SETTING

Prospective comparison of pulmonary function testing and respiratory muscle strength were made at the pediatric pulmonology and cardiopulmonary rehabilitation units of a university hospital.

PATIENT SAMPLE

Twenty-two patients with NMD and scoliosis, 17 patients with NMD without scoliosis, and 24 age- and sex-matched healthy controls. Outcome measures were compared in patients with NMD with and without scoliosis and healthy subjects using Student t test, Mann-Whitney U test, chi-square test, one-way analysis of variance (ANOVA), Kruskal-Wallis one-way ANOVA, Pearson correlation coefficients, and Spearman rank correlation, as appropriate.

OUTCOME MEASURES

1) Pulmonary function: forced vital capacity (FVC), forced expiratory volume in 1 second (FEV(1)), peak expiratory flow rate (PEF), forced expiratory flow between 25% and 75% of FVC (FEF(25-75%)), and maximum expiratory flows at 75%, 50%, and 25% of FVC (MEF(75), MEF(50), and MEF(25), respectively); 2) oxygen saturation: pulse oxymeter reading; and 3) respiratory muscle strength: maximal inspiratory mouth pressure (MIP) and maximal expiratory mouth pressure (MEP).

METHODS

Pulmonary function, oxygen saturation, MIP, and MEP were measured and compared in patients with NMD, patients with and without scoliosis, and in healthy subjects.

RESULTS

The patients with NMD, both with and without scoliosis, had significantly lower PEF, MIP, MEP, % predicted MIP (%MIP), and % predicted MEP (%MEP) than those of healthy subjects (p<.05). The patients with NMD and scoliosis had significantly lower values than those with NMD without scoliosis and controls (p<.05) for FVC, FEV(1), and FEF(25-75%).

CONCLUSION

Both inspiratory and expiratory muscle strength were diminished in patients with NMD compared with healthy controls. Significant differences were also noted in pulmonary function in patients with NMD with or without scoliosis. This suggests that NMD may impact respiratory function independently of the effects of scoliosis. Clinicians treating patients with NMD should be aware of the possibility of compromised respiratory function in these patients to address possible complications.

Rehabilitation management of neuromuscular disease: the role of exercise training

This paper summarizes the current state of knowledge regarding exercise and neuromuscular diseases/disorders (NMDs) and reviews salient studies in the literature. Unfortunately, there is inadequate evidence in much of the NMDs to make specific recommendations regarding exercise prescriptions. This review focuses on the role of exercise in a few of the specific NMDs where most research has taken place and recommends future research directions.

Abnormal cardiac morphology, function and energy metabolism in the dystrophic mdx mouse: an MRI and MRS study

Patients with muscular dystrophy have abnormal cardiac function and decreased high-energy phosphate metabolism. Here, we have determined whether the 8 month old mdx mouse, an animal model of muscular dystrophy, also has abnormal cardiac function and energetics. In vivo cardiac MRI revealed 33% and 104% larger right ventricular end-diastolic and end-systolic volumes, respectively, and 17% lower right ventricular ejection fractions in mdx mice compared with controls. Evidence of left ventricular diastolic dysfunction included 18% lower peak filling rates in mdx mouse hearts. Abnormal cardiac function was accompanied by necrosis and lower citrate synthase activity in the mdx mouse heart, suggesting decreased mitochondrial content. Decreased mitochondrial numbers were associated with 38% lower phosphocreatine concentration, 22% lower total creatine, 36% higher cytosolic free ADP concentration and 1.3 kJ/mol lower free-energy available from ATP hydrolysis in whole isolated, perfused mdx mouse hearts than in controls. Transsarcolemmal creatine uptake was 12% lower in mdx mouse hearts. We conclude that the absence of dystrophin in adult mdx mouse heart, as in the heart of human patient, is associated with right ventricular dilatation, left ventricular diastolic dysfunction and abnormal energy metabolism.

Comparison study of chest physiotherapy home training programmes on respiratory functions in patients with muscular dystrophy

Objective: To compare the effects of home training programmes, threshold inspiratory muscle training and breathing exercise on spirometry and maximal pressures in patients with muscular dystrophy.

Design: Prospective blinded 12-week study.

Settings: Cardiopulmonary department of university hospital.

Subjects: Twenty-three patients with muscular dystrophy (17 patients with limb girdle muscular dystrophy and 6 patients with Becker muscular dystrophy) assigned to the threshold inspiratory muscle training and breathing exercise groups with alternate allocation.

Methods: Spirometry, maximal inspiratory pressure (PImax) and maximal expiratory pressure (PEmax) were measured before and after training. In the threshold inspiratory muscle training group threshold pressure load was determined as equal to 30% of weekly PImaxmeasurement. In the breathing exercise group, patients performed deep and forceful diaphragmatic and segmental exercises. All patients performed exercises at home and once a week at hospital under supervision.

Results: The improvement of PImaxin the threshold inspiratory muscle training group was more significant than the improvement observed in the breathing exercise group (P= 0.05). PEmaxincreased significantly only in the breathing exercise group (P= 0.01). Spirometry results did not change significantly in both groups after the training.

Conclusions: We conclude that respiratory muscle strength is enhanced by training in the patients with muscular dystrophy who are ambulatory, but inspiratory and/or expiratory training effect is specific to the trained muscles. The techniques that improve the strength of respiratory muscles should be included in the physiotherapy management of patients with 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.

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 increasingly used to treat it.

OBJECTIVES

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

SEARCH STRATEGY

We searched the Cochrane Neuromuscular Disease Group Trials Register, MEDLINE (from January 1966 to June 2006), and EMBASE (from January 1980 to June 2006) for randomised trials and contacted authors of trials and other experts in the field.

SELECTION CRITERIA

We searched for quasi-randomised or randomised controlled trials of participants with neuromuscular or chest wall disorder-related stable chronic hypoventilation of all ages and all degrees of severity, receiving any type and any mode of nocturnal mechanical ventilation. The primary outcome measure was short-term and long-term reversal of hypoventilation related clinical symptoms and secondary outcomes were unplanned hospital admission, one year mortality, short-term and long-term reversal of daytime hypercapnia, improvement of lung function and sleep breathing disorders.

DATA COLLECTION AND ANALYSIS

We identified eight randomised trials.

MAIN RESULTS

The eight eligible trials included a total of 144 participants. The relative risk of 'no improvement of hypoventilation related clinical symptoms' in the short-term following nocturnal mechanical ventilation was available in only one trial with 10 participants and was not significant, 0.09 (95% confidence interval (CI) 0.01 to 1.31). The relative risk of 'no reversal of daytime hypercapnia' in the short-term following nocturnal ventilation was significant and favoured treatment, 0.37 (95% CI 0.20 to 0.65). The weighted mean difference of nocturnal mean oxygen saturation was 5.45% (95% CI 1.47 to 9.44) more improvement in participants treated with nocturnal mechanical ventilation. For most of the outcome measures there was no significant long-term difference between nocturnal mechanical ventilation and no ventilation. However, the estimated risk of death based on three studies was reduced following nocturnal ventilation, 0.62 (95% CI 0.42 to 0.91). There was considerable and significant heterogeneity between the trials possibly related to differences between the study populations. Most of the secondary outcomes were not assessed in the eligible trials. Data from two crossover trials suggested no evidence for a difference in reversal of daytime hypercapnia and sleep study parameters between volume-cycled and pressure-cycled ventilation. No data could be summarised for the comparisons between invasive and non-invasive mechanical ventilation or between intermittent positive pressure and negative pressure ventilation.

AUTHORS' 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. In three small studies survival was prolonged mainly in participants with motor neuron diseases. With the exception of motor neuron disease, further larger randomised 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 in neuromuscular and chest wall diseases and to compare the different types and modes of ventilation.

Hand versus mouth for call–bell activation by DMD and Becker patients

Severe hand dysfunction is common in patients with Duchenne muscular dystrophy (DMD) and may preclude the use of conventional call-bells. We prospectively evaluated a call-bell with two hand-controlled interfaces (push-button and key-pinch) and two mouth-controlled interfaces (sip-or-puff) in 32 consecutive DMD and Becker patients. Patients called intentionally 348 times, using the sip-or-puff device 237 times and the hand-controlled interfaces 147 times. Use of the hand-controlled interfaces correlated with key-pinch strength (R=0.366; P=0.04). Six patients reported being unable to call with the hand interfaces and five patients reported temporary call failure due to inaccessibility of the sip-or-puff interface. Ease-of-use scores on a visual analogue scale were best for puff, followed by sip then key-pinch interrupter and push-button (8.7+/-2.1, 7.5+/-2.7, 6.2+/-3.9, and 0.5+/-2.0 respectively; ANOVA: P<0.00001). In conclusion sip-or-puff devices should be considered more often to provide neuromuscular patients with greater independence.

Posterior spinal fusion for scoliosis in duchenne muscular dystrophy diminishes the rate of respiratory decline

STUDY DESIGN

To assess the rate of decline in pulmonary function in Duchenne muscular dystrophy (DMD) before and after posterior spinal fusion for scoliosis.

OBJECTIVE

To compare the rate of respiratory decline using percent normal forced vital capacity (%FVC) measurements before and after posterior spinal fusion.

SUMMARY OF BACKGROUND DATA

Posterior spinal fusion for scoliosis is used widely in DMD, although the long-term pulmonary effects have not been well established.

METHODS

Fifty-six patients were assessed. Percent forced vital capacity was the outcome parameter with data analysis using a mixed-model repeated-measures ANOVA and paired t tests. Group 1: Inclusion criteria were a diagnosis of DMD, 2 or more pulmonary function tests presurgery, and 2 or more postsurgery. Group 2: The rates of respiratory decline before and after spinal fusion for the whole study population were determined by within-subjects mixed-model regression analysis to account for the varying number of FVC studies between patients and unequal spacing between tests.

RESULTS

Group 1: 20 patients. Mean length of time of respiratory value determination was 2.5 +/- 1.0 years presurgery and 5.6 +/- 2.8 years postsurgery. Mean rate of decline presurgery was 8.0% +/- 4.1% per year, which decreased to 3.9% +/- 1.9% per year postsurgery (paired t test = 4.58, P < 0.0001). Group 2: 56 patients. The respiratory value determinations ranged from 4 years presurgery to 8 years postsurgery. The rates of respiratory decline based on the whole study population were 4% per year presurgery, which decreased to 1.75% per year postsurgery (F-test comparison of slopes = 19.71, P < 0.0001).

CONCLUSIONS

Posterior spinal fusion for scoliosis in DMD is associated with a significant decrease in the rate of respiratory decline postsurgery compared with presurgery rates.

Pulmonary rehabilitation in patients with neuromuscular disease

In neuromuscular disease (NMD) patients with progressive muscle weakness, respiratory muscles are also affected and hypercapnia can increase gradually as the disease progresses. The fundamental respiratory problems NMD patients experience are decreased alveolar ventilation and coughing ability. For these reasons, it is necessary to precisely evaluate pulmonary function to provide the proper inspiratory and expiratory muscle aids in order to maintain adequate respiratory function. As inspiratory muscle weakening progresses, NMD patients experience hypoventilation. At this point, respiratory support by mechanical ventilator should be initiated to relieve respiratory distress symptoms. Patients with adequate bulbar muscle strength and cognitive function who use a non-invasive ventilation aid, via a mouthpiece or a nasal mask, may have their hypercapnia and associated symptoms resolved. For a proper cough assist, it is necessary to provide additional insufflation to patients with inspiratory muscle weakness before using abdominal thrust. Another effective method for managing airway secretions is a device that performs mechanical insufflation-exsufflation. In conclusion, application of non-invasive respiratory aids, taking into consideration characterization of respiratory pathophysiology, have made it possible to maintain a better quality of life in addition to prolonging the life span of patients with NMD.