Respiratory muscle strength and cough capacity in patients with Duchenne muscular dystrophy

Effects of pulmonary function improvement devices in the pediatric population with cerebral palsy: Systematic review and meta-analysis of randomized clinical trials

INTRODUCTION

Enhancing lung function can significantly improve daily life functionality for children with cerebral palsy, leading to increased interest in respiratory physiotherapy training devices in clinical practice. This study aims to evaluate the efficacy of devices (inspiratory muscle training and feedback devices) for improving pulmonary function through various respiratory parameters.

METHODS

A systematic review with meta-analysis of randomized clinical trials was conducted in seven databases up until May 2023. The included studies focused on training inspiratory muscle function using specific devices (inspiratory muscle training and feedback devices) in children with cerebral palsy. The main outcomes were maximum expiratory pressure and maximum inspiratory pressure. Secondary outcomes included forced vital capacity, forced expiratory volume in 1 s, peak expiratory flow, and the Tiffenau index. The effects of respiratory treatment were calculated through the estimation of the effect size and its 95% confidence intervals. The risk of bias in the included studies was assessed using the Cochrane Collaboration's tool for assessing the risk of bias (RoB2).

RESULTS

Nine studies were included in the systematic review with meta-analysis, involving a total of 321 children aged between 6 and 18 years after secondary analyses were conducted. Feedback devices were found to be more effective in improving maximum expiratory pressure (effect size -0.604; confidence interval -1.368 to 0.161), peak expiratory flow, forced expiratory volume in 1 s, and forced vital capacity. Inspiratory muscle training devices yielded better effectiveness in improving maximum inspiratory pressure (effect size -0.500; confidence interval -1.259 to 0.259), the Tiffeneau index, and quality of life.

CONCLUSION

Both devices showed potential in improving pulmonary function in children with cerebral palsy. Further high-quality clinical trials are needed to determine the optimal dosage and the most beneficial device type for each pulmonary function parameter.

The effect of respiratory muscle training on children and adolescents with cystic fibrosis: a systematic review and meta-analysis

BACKGROUND

Cystic fibrosis is a chronic genetic disease that can affect the function of the respiratory system. Previous reviews of the effects of respiratory muscle training in people with cystic fibrosis are uncertain and do not consider the effect of age on disease progression. This systematic review aims to determine the effectiveness of respiratory muscle training in the clinical outcomes of children and adolescents with cystic fibrosis.

METHODS

Up to July 2023, electronic databases and clinical trial registries were searched. Controlled clinical trials comparing respiratory muscle training with sham intervention or no intervention in children and adolescents with cystic fibrosis. The primary outcomes were respiratory muscle strength, respiratory muscle endurance, lung function, and cough. Secondary outcomes included exercise capacity, quality of life and adverse events. Two review authors independently extracted data and assessed study quality using the Cochrane Risk of Bias Tool 2. The certainty of the evidence was assessed according to the GRADE approach. Meta-analyses where possible; otherwise, take a qualitative approach.

RESULTS

Six studies with a total of 151 participants met the inclusion criteria for this review. Two of the six included studies were published in abstract form only, limiting the available information. Four studies were parallel studies and two were cross-over designs. There were significant differences in the methods and quality of the methodology included in the studies. The pooled data showed no difference in respiratory muscle strength, lung function, and exercise capacity between the treatment and control groups. However, subgroup analyses suggest that inspiratory muscle training is beneficial in increasing maximal inspiratory pressure, and qualitative analyses suggest that respiratory muscle training may benefit respiratory muscle endurance without any adverse effects.

CONCLUSIONS

This systematic review and meta-analysis indicate that although the level of evidence indicating the benefits of respiratory muscle training is low, its clinical significance suggests that we further study the methodological quality to determine the effectiveness of training.

TRIAL REGISTRATION

The protocol for this review was recorded in the International Prospective Register of Systematic Reviews (PROSPERO) under registration number CRD42023441829.

Effects of Rehabilitative Intervention for Augmenting Cough Function in Patients with Multiple System Atrophy

Objectives

One of the causes of death in patients with multiple system atrophy (MSA) is aspiration pneumonia caused by cough dysfunction. This study aimed to identify an effective approach to improve coughing and to explore the establishment of criteria for the use of gastrostomy based on cough and respiratory dysfunctions.

Methods

Eighteen probable MSA patients participated in the study. They were categorized into air stacking and non-air stacking groups. First, we investigated how the inspiration volume changes by applying maximum insufflation capacity (MIC). Second, peak cough flow (PCF) was measured by different cough augmentation methods: 1) spontaneous coughing (SpC); 2) SpC with MIC (SpC + MIC); 3) SpC with manually assisted cough (MAC) (SpC + MAC); and 4) SpC with MIC and MAC (SpC + MIC + MAC). Among these four conditions, PCF values were compared to determine the most effective approach for cough augmentation. Receiver operating characteristic analysis was performed on percent forced vital capacity (%FVC) to determine an index for discriminating PCF below160 L/min, which indicates a high risk of suffocation, involving SpC and SpC + MIC.

Results

Inspiration volume increased significantly with MIC in both groups (P < 0.05), and PCF increased significantly with MIC in the air stacking group (P < 0.01). PCF could not be maintained at 160 L/min when %FVC fell below 59%, even when MIC was applied.

Conclusions

PCF increases with MIC in patients with MSA. It may be meaningful to consider the timing of gastrostomy introduction based on the severity of cough and respiratory dysfunction.

Respiratory Management of Patients With Neuromuscular Weakness: An American College of Chest Physicians Clinical Practice Guideline and Expert Panel Report

BACKGROUND

Respiratory failure is a significant concern in neuromuscular diseases (NMDs). This CHEST guideline examines the literature on the respiratory management of patients with NMD to provide evidence-based recommendations.

STUDY DESIGN AND METHODS

An expert panel conducted a systematic review addressing the respiratory management of NMD and applied the Grading of Recommendations, Assessment, Development, and Evaluations approach for assessing the certainty of the evidence and formulating and grading recommendations. A modified Delphi technique was used to reach a consensus on the recommendations.

RESULTS

Based on 128 studies, the panel generated 15 graded recommendations, one good practice statement, and one consensus-based statement.

INTERPRETATION

Evidence of best practices for respiratory management in NMD is limited and is based primarily on observational data in amyotrophic lateral sclerosis. The panel found that pulmonary function testing every 6 months may be beneficial and may be used to initiate noninvasive ventilation (NIV) when clinically indicated. An individualized approach to NIV settings may benefit patients with chronic respiratory failure and sleep-disordered breathing related to NMD. When resources allow, polysomnography or overnight oximetry can help to guide the initiation of NIV. The panel provided guidelines for mouthpiece ventilation, transition to home mechanical ventilation, salivary secretion management, and airway clearance therapies. The guideline panel emphasizes that NMD pathologic characteristics represent a diverse group of disorders with differing rates of decline in lung function. The clinician's role is to add evaluation at the bedside to shared decision-making with patients and families, including respect for patient preferences and treatment goals, considerations of quality of life, and appropriate use of available resources in decision-making.

The role of lung volume recruitment therapy in neuromuscular disease: a narrative review

Respiratory muscle weakness results in substantial discomfort, disability, and ultimately death in many neuromuscular diseases. Respiratory system impairment manifests as shallow breathing, poor cough and associated difficulty clearing mucus, respiratory tract infections, hypoventilation, sleep-disordered breathing, and chronic ventilatory failure. Ventilatory support (i.e., non-invasive ventilation) is an established and key treatment for the latter. As survival outcomes improve for people living with many neuromuscular diseases, there is a shift towards more proactive and preventative chronic disease multidisciplinary care models that aim to manage symptoms, improve morbidity, and reduce mortality. Clinical care guidelines typically recommend therapies to improve cough effectiveness and mobilise mucus, with the aim of averting acute respiratory compromise or respiratory tract infections. Moreover, preventing recurrent infective episodes may prevent secondary parenchymal pathology and further lung function decline. Regular use of techniques that augment lung volume has similarly been recommended (volume recruitment). It has been speculated that enhancing lung inflation in people with respiratory muscle weakness when well may improve respiratory system "flexibility", mitigate restrictive chest wall disease, and slow lung volume decline. Unfortunately, clinical care guidelines are based largely on clinical rationale and consensus opinion rather than level A evidence. This narrative review outlines the physiological changes that occur in people with neuromuscular disease and how these changes impact on breathing, cough, and respiratory tract infections. The biological rationale for lung volume recruitment is provided, and the clinical trials that examine the immediate, short-term, and longer-term outcomes of lung volume recruitment in paediatric and adult neuromuscular diseases are presented and the results synthesised.

The Association between the Respiratory System and Upper Limb Strength in Males with Duchenne Muscular Dystrophy: A New Field for Intervention?

Progressive, irreversible muscle weakness is the leading symptom of Duchenne muscular dystrophy (DMD), often resulting in death from respiratory muscle failure. Little is known about the relationship between the functioning of the respiratory system and the hand grip-a function which remains long preserved. This study aimed to investigate the interdependence between muscle strength and the function of both hand grip and the respiratory system in patients with DMD.

MATERIALS AND METHOD

The study included cohort patients, aged 6-17, with DMD, recruited from the Rare Disease Centre, Gdansk, Poland. Clinical status (Vignos scale, Brook scale), pulmonary function (respiratory muscle strength-MIP, MEP); spirometry (FEV1; FVC), as well as upper limb function (performance of the upper limb-PUL 2.0) and hand grip strength (HGS) (hand-held dynamometer) were evaluated in all participants.

RESULTS

Finally, 53 boys (mean age 11.41 ± 3.70 years, 25 non-ambulant) were included. Each of the participants presented a lower %pv of MIP (48.11 ± 27), MEP (38.11 ± 22), PUL (75.64 ± 27), and HGS (33.28 ± 18). There were differences between the ambulatory and non-ambulatory groups in values of MIP, MEP, FVC, PUL, HGS (p < 0.001 for all), and FEV1 (p < 0.013). There were correlations between PUL, HGS, and MIP (R = 0.56; R = 0.61, p < 0.001 both), MEP (R = 0.59; R = 0.62, p < 0.001), FVC (R = 0.77; R = 0.77, p < 0.001), and FEV1 (R = 0.77; R = 0.79; p < 0.001). These correlations were found for all participants, but non-ambulatory patients presented stronger relationships.

CONCLUSIONS

1. The pulmonary and upper limb functions were within the normal range in ambulatory and low in non-ambulatory patients with DMD, but the muscle strength of both systems was low, regardless of the stage of the disease. 2. There seems to be an interdependence between the respiratory system and upper limb strength in terms of muscle strength and function in DMD patients, which is stronger in non-ambulatory patients. This may be the basis for the creation of a new personalized plan in rehabilitation-the simultaneous rehabilitation of the respiratory and upper limb muscles. Further studies on this theory should be conducted.

Routine lung volume recruitment in boys with Duchenne muscular dystrophy: a randomised clinical trial

BACKGROUND

Impaired cough results in airway secretion retention, atelectasis and pneumonia in individuals with Duchenne muscular dystrophy (DMD). Lung volume recruitment (LVR) stacks breaths to inflate the lungs to greater volumes than spontaneous effort. LVR is recommended in DMD clinical care guidelines but is not well studied. We aimed to determine whether twice-daily LVR, compared with standard of care alone, attenuates the decline in FVC at 2 years in boys with DMD.

METHODS

In this multicentre, assessor-blinded, randomised controlled trial, boys with DMD, aged 6-16 years with FVC >30% predicted, were randomised to receive conventional treatment or conventional treatment plus manual LVR twice daily for 2 years. The primary outcome was FVC % predicted at 2 years, adjusted for baseline FVC % predicted, age and ambulatory status. Secondary outcomes included change in chest wall distensibility (maximal insufflation capacity minus FVC) and peak cough flow.

RESULTS

Sixty-six boys (36 in LVR group, 30 in control) were evaluated (median age (IQR): 11.5 years (9.5-13.5), median baseline FVC (IQR): 85% predicted (73-96)). Adjusted mean difference in FVC between groups at 2 years was 1.9% predicted (95% CI -6.9% to 10.7%; p=0.68) in the direction of treatment benefit. We found no differences in secondary outcomes.

CONCLUSION

There was no difference in decline in FVC % predicted with use of twice-daily LVR for boys with DMD and relatively normal lung function. The burden associated with routine LVR may outweigh the benefit. Benefits of LVR to maintain lung health in boys with worse baseline lung function still need to be clarified.

TRIAL REGISTRATION NUMBER

NCT01999075.

Characterizing Expiratory Respiratory Muscle Degeneration in Duchenne Muscular Dystrophy Using MRI

BACKGROUND

Expiratory muscle weakness and impaired airway clearance are early signs of respiratory dysfunction in Duchenne muscular dystrophy (DMD), a degenerative muscle disorder in which muscle cells are damaged and replaced by fibrofatty tissue. Little is known about expiratory muscle pathology and its relationship to cough and airway clearance capacity; however, the level of muscle replacement by fat can be estimated using MRI and expressed as a fat fraction (FF).

RESEARCH QUESTION

How does abdominal expiratory muscle fatty infiltration change over time in DMD and relate to clinical expiratory function?

STUDY DESIGN AND METHODS

Individuals with DMD underwent longitudinal MRI of the abdomen to determine FF in the internal oblique, external oblique, and rectus abdominis expiratory muscles. FF data were used to estimate a model of expiratory muscle degeneration by using nonlinear mixed effects and a cumulative distribution function. FVC, maximal inspiratory and expiratory pressures, and peak cough flow were collected as clinical correlates to MRI.

RESULTS

Forty individuals with DMD (aged 6-18 years at baseline) participated in up to five visits over 36 months. Modeling estimated the internal oblique progresses most quickly and reached 50% replacement by fat at a mean patient age of 13.0 years (external oblique, 14.0 years; rectus abdominis, 16.2 years). Corticosteroid-untreated individuals (n = 4) reached 50% muscle replacement by fat 3 to 4 years prior to treated individuals. Individuals with mild clinical dystrophic phenotypes (n = 3) reached 50% muscle replacement by fat 4 to 5 years later than corticosteroid-treated individuals. Internal and external oblique FFs near 50% were associated with maximal expiratory pressures < 60 cm H₂O and peak cough flows < 270 L/min.

INTERPRETATION

These data improve understanding of the early phase of respiratory compromise in DMD, which typically presents as airway clearance dysfunction prior to the onset of hypoventilation, and links expiratory muscle fatty infiltration to pulmonary function measures.

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.

Non-Invasive Respiratory Assessment in Duchenne Muscular Dystrophy: From Clinical Research to Outcome Measures

Ventilatory failure, due to the progressive wasting of respiratory muscles, is the main cause of death in patients with Duchenne muscular dystrophy (DMD). Reliable measures of lung function and respiratory muscle action are important to monitor disease progression, to identify early signs of ventilatory insufficiency and to plan individual respiratory management. Moreover, the current development of novel gene-modifying and pharmacological therapies highlighted the urgent need of respiratory outcomes to quantify the effects of these therapies. Pulmonary function tests represent the standard of care for lung function evaluation in DMD, but provide a global evaluation of respiratory involvement, which results from the interaction between different respiratory muscles. Currently, research studies have focused on finding novel outcome measures able to describe the behavior of individual respiratory muscles. This review overviews the measures currently identified in clinical research to follow the progressive respiratory decline in patients with DMD, from a global assessment to an individual structure–function muscle characterization. We aim to discuss their strengths and limitations, in relation to their current development and suitability as outcome measures for use in a clinical setting and as in upcoming drug trials in DMD.

Effects of Physical Therapist Intervention on Pulmonary Function in Children With Cerebral Palsy: A Systematic Review and Meta-Analysis

OBJECTIVE

The purpose of this study was to evaluate the effects of physical therapy on pulmonary function and respiratory muscle strength in children with cerebral palsy (CP).

METHODS

A search of 10 databases was conducted for this systematic review. Initially, there were no language, study design, or time frame restrictions. All studies assessing the effect of physical therapy on the respiratory system in children with CP were included. Two reviewers independently extracted and documented data. The data extracted included description of the intervention (duration, therapeutic method) and study results (change of spirometric parameters, respiratory muscle strength). The effects of physical therapist treatment were calculated using software.

RESULTS

A total of 269 children aged 5 to 18 years from 10 studies were included. The included studies consisted of 5 different therapeutic methods (inspiratory muscle training [IMT], aerobic training, swimming, respiratory exercise, exercise with elastic bands). Physical therapist intervention led to a significant increase in the maximal expiratory pressure (MEP) (I2 = 0%), peak expiratory flow (I2 = 0%), and maximum oxygen consumption (I2 = 37%). A separate analysis of the most frequently used therapy (IMT) showed a positive effect on MEP (I2 = 0%) and maximal inspiratory pressure (I2 = 35%).

CONCLUSION

Various forms of physical therapy have potential to demonstrate a positive effect on maximal inspiratory pressure, MEP, and peak expiratory flow in children with CP. There is no possibility to recommend the best method and duration of the physical therapy; however, it can be suggested that physical therapy should be applied for at least 4 weeks and include IMT.

IMPACT

CP is one of the most common causes of physical disabilities in children, and pulmonary dysfunction is the leading cause of death in people with CP. Thus, it is warranted to seek different approaches that may improve pulmonary function in people with CP. This review has shown that various forms of physical therapy have potential to improve the pulmonary function of children with CP.

Objective measurement of lung volume recruitment therapy: laboratory and clinical validation

Lung volume recruitment manoeuvres are often prescribed to maintain respiratory health in neuromuscular disease. Unfortunately, no current system accurately records delivered dose. This study determined the performance characteristics of a novel, objective, manual lung volume recruitment bag counter (‘the counter’) with bench and healthy volunteer testing, as well as in individuals with neuromuscular disease. We undertook (1) bench test determination of activation threshold, (2) bench and healthy volunteer fidelity testing during simulated patient interface leak and different pressure compressions and (3) comparisons with self-report in individuals with neuromuscular disease. The data are reported as summary statistics, compression counts, percentage of recorded versus delivered compressions and concordance (Cohen’s kappa (K) and absolute agreement).

Development of clinical practice guidelines for allied health and nursing assessment and management of Duchenne muscular dystrophy

PURPOSE

To provide evidence-based guidance specific to allied health and nursing practice for the assessment and management of individuals with Duchenne muscular dystrophy (DMD).

MATERIALS AND METHODS

Thirteen key focus areas were identified in consultation with health professionals and consumer advocacy groups. A series of systematic literature reviews were conducted to identify assessment and management strategies for each key focus area. A consensus process using modified Delphi methodology, including an Australia-New Zealand expert consensus meeting, was conducted. Recommendations underwent consultative review with key groups before being finalised and prepared for dissemination.

RESULTS

This clinical practice guideline (CPG) generated 19 evidence-based recommendations, 117 consensus-based recommendations and five research recommendations across the 13 focus areas to inform allied health assessment and management of individuals with DMD.

CONCLUSIONS

The resulting recommendations can be used in conjunction with existing medical CPGs to improve, standardise and advocate for allied health and rehabilitation care in DMD. The process used here may be useful for the development of CPGs in other rare diseases.Implications for rehabilitationImplementation-ready evidence-based statements to guide clinical care of individuals with DMD are provided with the potential to improve participation, function in the community and quality of life.A model for developing best practice statements for other rare neurological diseases is described.Allied health and nursing health professionals should focus research efforts to generate quality evidence to support rehabilitation practice.

RESPIRATORY MUSCLE IMPAIRMENT EVALUATED WITH MEP/MIP RATIO IN CHILDREN AND ADOLESCENTS WITH CHRONIC RESPIRATORY DISEASE

OBJECTIVE

To evaluate the strength of respiratory muscles and to compare maximum inspiratory (MIP) and expiratory (MEP) pressure and MEP/MIP ratio between patients with chronic respiratory diseases and healthy individuals.

METHODS

Case-control study. Individuals with neuromuscular disease and post-infectious bronchiolitis obliterans were considered. In addition, they were also matched according to anthropometric and demographic characteristics with healthy children and adolescents. MIP, MEP in the three groups, and pulmonary function only in patients with chronic respiratory diseases were recorded.

RESULTS

A total of 52 subjects with CRD (25 with neuromuscular disease, and 27 with post-infectious bronchiolitis obliterans) and 85 healthy individuals were included, with an average age of 11.3±2.1 years. Patients with neuromuscular disease and post-infectious bronchiolitis obliterans presented lower MIP and MEP when compared with healthy individuals, although MEP/MIP ratio was lower in patients with neuromuscular disease (0.87±0.3) and higher in patients with post-infectious bronchiolitis obliterans (1.1±0.3) compared to the healthy group (0.97±0.2). Only in patients with neuromuscular disease a negative correlation was observed between MEP/MIP ratio and age (r=-0.50; p=0.01).

CONCLUSIONS

Differences in the pattern of muscular weakness between patients with chronic respiratory diseases were observed. In patients with neuromuscular disease, a decrease in the MEP/MIP ratio depending on MIP was verified; and in those patients with post-infectious bronchiolitis obliterans, an increase in the MEP/MIP ratio depending on MIP was also observed.

Relationship between Eating and Digestive Symptoms and Respiratory Function in Advanced Duchenne Muscular Dystrophy Patients

Background:

Duchenne muscular dystrophy (DMD) patients can have various issues that affect their quality of life, including eating and digestive conditions.

Objective:

We sought to identify the relationship between respiratory function and various eating and digestion related symptoms in patients with advanced Duchenne muscular dystrophy (DMD).

Methods:

Eating and digestive symptoms, including loss of appetite, nausea, vomiting, diarrhea, constipation, swallowing difficulty, mastication difficulty, early satiety, and aspiration, were evaluated among patients with advanced DMD who were nonambulatory and required noninvasive mechanical ventilatory support. In addition, various respiratory function parameters were measured, including forced vital capacity (FVC), maximal insufflation capacity (MIC), peak cough flow (PCF), assisted PCF (APCF), maximal inspiratory pressure (MIP), and maximal expiratory pressure (MEP). We then analyzed the relationship between gastrointestinal symptoms and respiratory function parameters.

Results:

A total of 180 patients (age, 22.3±5.0 years) were included in the analysis. Loss of appetite and early satiety showed no correlation with any of the respiratory function parameters. Constipation was correlated with MEP; swallowing difficulty was correlated with MIC, APCF, MIP and MEP; and mastication difficulty was correlated with FVC, PCF, APCF, MIP, and MEP. Notably, age did not correlate with any gastrointestinal symptoms.

Conclusions:

Eating and digestive symptoms are more closely correlated with respiratory function than with age in patients with DMD. We think this correlation is mainly caused by the skeletal muscle strength, which is major determinant of both digestive and respiratory function.

Comprehensive Respiratory Muscle Training Improves Pulmonary Function and Respiratory Muscle Strength in Acute Stroke Patients

PURPOSE

To evaluate the effects of respiratory muscle training (RMT) on pulmonary function, respiratory complications, and stroke-related disabilities in patients with acute stroke.

METHODS

One hundred twenty-two subjects with stroke admitted to the stroke rehabilitation center of Inje Hospital between August 2016 and May 2018 were recruited. After the initial exclusion, the remaining patients were assigned to the RMT group (36 patients) or the standard rehabilitation (SR) group (28 patients who did not undergo RMT). A total of 44 patients completed the study, with 22 patients in each group. The RMT program consisted of air-stacking exercise, manually assisted coughing, inspiratory and expiratory muscle strengthening, cough exercises, and respiratory reeducation. Pulmonary function and respiratory muscle strength were evaluated before commencement and after 1 mo of RMT. The Functional Ambulation Category score, Korean version of the Modified Barthel Index, Shoulder Abduction and Finger Extension score, and handgrip power were assessed. The incidence of pneumonia was also evaluated.

RESULTS

Both pulmonary function and respiratory muscle strength significantly improved in both groups. However, differences (%) in the RMT group was greater for all parameters of pulmonary function and respiratory muscle strength. Respiratory complications at 1 yr were significantly lower in the RMT group (P = .016).

CONCLUSION

Four weeks of comprehensive RMT in patients with acute stroke resulted in significantly greater improvements in both pulmonary function and respiratory muscle strength than SR. Therefore, RMT has the potential to reduce post-stroke respiratory complications.

DMD-related muscular dystrophy in Cameroon: Clinical and genetic profiles

BACKGROUND

Most of the previous studies on Duchenne Muscular Dystrophy (DMD) were conducted in Caucasian, Asian, and Arab populations. Therefore, little is known about the features of this disease in Africans. In this study, we aimed to determine the clinical characteristics of DMD, and the common mutations associated with this condition in a group of Cameroonian patients.

METHODS

We recruited DMD patients and performed a general physical examination on each of them. Multiplex ligand-dependant probe amplification was carried out to investigate exon deletions and duplications in the DMD gene (OMIM: 300377) of patients and their mothers.

RESULTS

A total of 17 male patients from 14 families were recruited, aged 14 ± 5.1 (8-23) years. The mean age at onset of symptoms was 4.6 ± 1.5 years, and the mean age at diagnosis was 12.1 ± 5.2 years. Proximal muscle weakness was noted in all patients and calf hypertrophy in the large majority of them (88.2%; 15/17). Flexion contractures were particularly frequent on the ankle (85.7%; 12/14). Wasting of shoulder girdle and thigh muscles was present in 50% (6/12) and 46.2% (6/13) of patients, respectively. No patient presented with hearing impairment. Deletions in DMD gene (OMIM: 300377) occurred in 45.5% of patients (5/11), while duplications were observed in 27.3% (3/11). Both mutation types were clustered between exons 45 and 50, and the proportion of de novo mutation was estimated at 18.2% (2/11).

CONCLUSION

Despite the first symptoms of DMD occurring in infancy, the diagnosis is frequently made later in adolescence, indicating an underestimation of the number of cases of DMD in Cameroon. Future screening of deletions and duplications in patients from Cameroon should focus on the distal part of the gene.

Correlation of Bone Mineral Density with Pulmonary Function in Advanced Duchenne Muscular Dystrophy

BACKGROUND

A relationship between bone mineral density (BMD) and physical function has been revealed in the general population and various diseases. However, there is a lack of research investigating the correlation between BMD and respiratory function, one of few measurable physical parameters in patients with advanced Duchenne muscular dystrophy (DMD).

OBJECTIVE

To determine whether pulmonary function parameters, including respiratory muscle strength, are related to BMD.

DESIGN

Retrospective observational study.

SETTING

A tertiary university hospital.

PATIENTS

DMD patients who were over 20 years of age, nonambulatory, and supported by mechanical ventilators.

METHODS

The patients' age, weight, and pulmonary function as well as the BMD of the first and the fourth lumbar vertebra were assessed. Pulmonary function includes forced vital capacity (FVC), unassisted and assisted peak cough flow (UPCF and APCF), maximal expiratory pressure (MEP), and maximal inspiratory pressure (MIP).

MAIN OUTCOME MEASURES

A bivariate correlation for BMD and other pulmonary parameters was calculated, and hierarchical regression analysis was used to determine predictors of spine Z-score.

RESULTS

It was observed that the decrease in the spine BMD was not significantly correlated with age. However, the body mass index (BMI) and all parameters of pulmonary function were correlated with BMD. Partial correlation analysis adjusted by BMI showed that UPCF and APCF were powerful predictors of spine BMD.

CONCLUSIONS

The BMD of the lumbar spine correlated with BMI and PCF in patients with DMD at an advanced stage.

Cough and airway clearance in Duchenne muscular dystrophy

People with Duchenne muscular dystrophy (DMD), develop a respiratory muscle weakness that results in weakened cough, airway clearance impairment and over time respiratory failure and death. Assessment of cough effectiveness through vital capacity, peak cough flow and maximal inspiratory and expiratory pressures has been used to identify the optimal timing of cough augmentation techniques initiation. The choice of therapies depends on physician knowledge, and patient/care giver abilities. The purpose of this review is to clarify mechanisms of action, benefits and disadvantages of available techniques, such as manual cough-assisting manoeuvres, glossopharyngeal breathing, air stacking by resuscitator bag or by volume-cycle ventilator, and mechanical insufflator-exsufflator. Mechanisms of mucus mobilization, like intrapulmonary percussive ventilation, may have a therapeutic role in the case of persistent atelectasis. It is also crucial to recognize the initial phase of an acute respiratory exacerbation, increase the use of these techniques which may reduce morbidity and mortality.

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.

Posture and firmness changes in a pressure-relieving air mattress affect cough strength in elderly people with dysphagia

Dysphagia is the major pathophysiologic mechanism leading to aspiration pneumonia in the elderly. Elderly people with dysphagia who show low levels of the cough peak flow (CPF) are at greater risk for aspiration pneumonia. It has been reported that CPF values were significantly lower in the “soft” versus “hard” mode of a pressure-relieving air mattress in healthy volunteers in a supine position. Parameters such as spinal curvature, however, were not evaluated in detail. In this study, we clarified whether the changes in posture associated with two different firmness levels of a pressure-relieving air mattress were associated with cough production and related factors in the elderly with dysphagia. The body sinking distance, pelvic tilt angle, and immersion of the lumbar spine were measured to evaluate changes in posture. Forty subjects met the study criteria for dysphagia. The “soft” mode showed significantly lower CPF values than the “hard” mode (soft 274.9 ± 107.2 L/min vs. hard 325.0 ± 99.5 L/min, MD 50.0 95%CI 33.1–66.9 P < 0.001). Values of forced vital capacity (FVC) and maximal inspiratory pressure (PImax) were significantly lower in the “soft” mode than in the “hard” mode (MD 0.10 95%CI 0.04–0.17, P = 0.002, MD 3.2 95%CI 0.9–5.5, P = 0.007, respectively). Although there was no significant difference between the two firmness levels, maximal expiratory pressure (PEmax) values also tended to be lower in the “soft” than in the “hard” mode, (MD 2.9 95%CI -0.6–6.3 P = 0.1). At both firmness levels, CPF values were significantly correlated with FVC, PImax, and PEmax. The difference in sinking distance in the anterior superior iliac spine was significantly larger than that in the lesser tubercle of the humerus and patella. Additionally, in the soft mode, the pelvic tilt angle and contact area around the lumbar spine were significantly larger than those observed in the “hard” mode. Parameters associated with the production of cough, including inspiratory muscle strength, lung volume, and ultimately CPF, may be affected by immersion of the lumbar spine and curvature of the spine that results from the “soft” mode in elderly patients with dysphagia.

Assessment of diaphragmatic thickness by ultrasonography in Duchenne muscular dystrophy (DMD) patients

Introduction

In Duchenne muscular dystrophy (DMD) the assessment of diaphragmatic function is crucial because respiratory muscle weakness can cause respiratory failure. We aimed to noninvasively assess diaphragmatic function in DMD by measuring diaphragmatic thickness by ultrasonography, under the hypothesis that the progressive decrease of lung function is related to alterations of diaphragmatic thickness.

Methods

Forty-four DMD patients and thirteen healthy controls were enrolled and subdivided into three age groups. Diaphragmatic thickness was measured during quiet breathing, inspiratory capacity, maximal inspiratory pressure and expiratory pressure maneuvers.

Results

In DMD, absolute values of diaphragmatic thickness were significantly lower than in controls in the majority of the manoeuvers and diaphragmatic thickness significantly decreased with age at end-expiration, remaining constant at end-inspiration and during maximal inspiratory pressure maneuvers. Comparing to controls, absolute values of diaphragmatic thickness and diaphragmatic thickness variations were significantly lower (p<0.001), with the exception of quiet breathing and maximal expiratory pressure maneuvers in the youngest DMD. During maximal inspiratory pressure maneuver, variation of diaphragmatic thickness was not significantly different in the all groups, nevertheless maximal inspiratory pressure decreases with age.

Conclusions

The diaphragm is prone to pseudo-hypertrophy in the youngest DMD, and to progressive atrophy in middle-age and oldest DMD. Diaphragm impairment could be expressed as a dissociation between muscle drive and muscle developed force. Ultrasonography could be used as a noninvasive method to assess progressive diaphragmatic weakness.

Peak expiratory flow in obese subjects in different positions

Objective: To analyze the peak expiratory flow (PEF) in obese subjects in standing (ST), seated (SE), supine (SU), prone (PR), and right and left lateral decubitus (RL and LL) positions. Methods: 36 obese volunteers, aged between 18 and 54 years, and nonsmokers, were evaluated by anthropometric data; spirometry; international physical activity questionnaire (IPAQ); and PEF in ST, SE, SU, PR, RL, and LL positions, randomly. Results: The mean age was 27.3 ± 7.4 years and BMI of 38.7 ± 3.2 kg/m²; IPAQ results: active (50%), irregularly active (25%), very active (16.7%), and sedentary (08.3%); spirometry results: FVC = 100.33%, FEV₁ = 92.83%, FEV₁/FVC ratio = 0.95, FEF_25-75% = 85.55%. The PEF (L/min) were within the normal range and there was no difference between the ST and SE (428.6 ± 100.9 and 430.0 ± 100.1). Comparing ST and SE to the other positions, in absolute and percent of predicted values (L/min and %), there was a decrease in the SU (85.4 ± 14.9), PR (401.1 ± 92.4 and 84.1 ± 14.4), RL (398.6 ± 94.7 and 83.3 ± 14.9) (p < 0.05), and there was no difference to SU (409.4 ± 102.8) and LL (410.3 ± 93.9 and 85.8 ± 14.5). Conclusion: The PEF of healthy obese are similar in the standing and seated positions. The PEF decreases in the lying positions, except for the LL, that could be used as an alternative for measurements.

Analysis of Pulmonary Function Test in Korean Patients With Duchenne Muscular Dystrophy: Comparison of Foreign and Korean Reference Data

Objective

To determine the abnormal pulmonary function value in Korean Duchenne muscular dystrophy (DMD) patients, we performed a comparative analysis of the patients' pulmonary function value expressed as % of the overseas reference data and Korean healthy children and adolescent reference data.

Methods

We performed pulmonary function test (PFT) in a total of 27 DMD patients. We compared the patients' FVC% and FEV1% of the overseas reference data with those of the Korean children and adolescent reference data. Also, we compared the patients' MIP% and MEP% of the prediction equation data with those of the Korean children and adolescent reference data.

Results

Age of the subjects ranged from 8 to 16 years (12.03±2.27 years). The mean maximal expiratory pressure (MEP), maximal inspiratory pressure (MIP), vital capacity (VC), forced vital capacity (FVC), forced expiratory volume in 1 second (FEV1), and peak cough flow (PCF) were 36.93±9.5 cmH₂O, 45.79±17.46 cmH₂O, 1.4±0.43 L, 1.45±0.45 L, 1.40±0.41 L, and 206.25±61.21 L/min, respectively. The MIP%, MEP%, and FVC% of the Korean children and adolescent reference data showed statistically significant higher values than those of the prediction equation data.

Conclusion

We observed a clear numeric difference between Korean DMD patients' pulmonary function value expressed as % of the overseas data and inland data. To perform a precise assessment of respiratory function and to determine appropriate respiratory therapy, pulmonary function values of Korean DMD patients should be interpreted taking into account the inland normal pulmonary function test data.

Effect of Different Levels of Pressure Relieving Air-Mattress Firmness on Cough Strength

Cough is an important host-defense mechanism. The elderly and patients who are severely ill cannot cough effectively when lying in the supine position. Furthermore, pressure relieving air-mattresses are recommended for preventing the development of pressure ulcers. In this study, we clarified whether or not the cough peak flow (CPF), an index of cough strength, is affected by different firmness levels of a pressure relieving air-mattress in healthy volunteers in the supine position. Fifty-two healthy young men participated. All the measurements were carried out on each participant in the supine position on a pressure relieving air-mattress. The participants were assessed at two firmness levels, a "hard" and "soft" mode. The CPF, forced vital capacity (FVC), maximal expiratory pressure (PEmax), and maximal inspiratory pressure (PImax) were determined for each mode. The sinking distance of the body into the mattress was measured without any activity and the difference between the sinking distances of the two firmness levels was determined. The CPF, FVC, PEmax, and PImax were determined for each mode. The sinking distance of the body into the mattress was measured and the difference between the sinking distances of the two firmness levels was determined. The CPF, FVC, PEmax and PImax values of the participants coughing on the mattress were significantly lower when the mattress was in "soft" than in "hard" mode. The differences between the sinking distances of the mattress in "soft" and "hard" modes were larger for the anterior superior iliac spine. A harder mattress may lead to increased CPF in healthy young men lying in the supine position, and increased CPF may be important for host defense.

Assessment and management of respiratory function in patients with Duchenne muscular dystrophy: current and emerging options

Duchenne muscular dystrophy (DMD) is an X-linked myopathy resulting in progressive weakness and wasting of all the striated muscles including the respiratory muscles. The consequences are loss of ambulation before teen ages, cardiac involvement and breathing difficulties, the main cause of death. A cure for DMD is not currently available. In the last decades the survival of patients with DMD has improved because the natural history of the disease can be changed thanks to a more comprehensive therapeutic approach. This comprises interventions targeted to the manifestations and complications of the disease, particularly in the respiratory care. These include: 1) pharmacological intervention, namely corticosteroids and idebenone that significantly reduce the decline of spirometric parameters; 2) rehabilitative intervention, namely lung volume recruitment techniques that help prevent atelectasis and slows the rate of decline of pulmonary function; 3) scoliosis treatment, namely steroid therapy that is used to reduce muscle inflammation/degeneration and prolong ambulation in order to delay the onset of scoliosis, being an additional contribution to the restrictive lung pattern; 4) cough assisted devices that improve airway clearance thus reducing the risk of pulmonary infections; and 5) non-invasive mechanical ventilation that is essential to treat nocturnal hypoventilation, sleep disordered breathing, and ultimately respiratory failure. Without any intervention death occurs within the first 2 decades, however, thanks to this multidisciplinary therapeutic approach life expectancy of a newborn with DMD nowadays can be significantly prolonged up to his fourth decade. This review is aimed at providing state-of-the-art methods and techniques for the assessment and management of respiratory function in DMD patients.

Cough ability measurements and recurrent respiratory symptoms in individuals with Ataxia Telangiectasia

OBJECTIVES

Ataxia-Telangiectasia (A-T) individuals often present with respiratory muscle weakness, causing recurrent respiratory system infections, asthma-like symptoms, and chronic cough life-threatening events. The cough flow volume maneuver may reveal powerless airflow needed for efficient cough. The study aims to explore cough ability in relation to the flow/volume maneuver.

METHODS

Data collected retrospectively from clinical charts of 35 A-T patients (age 12.7 ± 4.9 years) included forced expiratory and cough flow/volume maneuvers performed on the same day. Analysis compared among the maneuvers matching indices, numbers of cough-spikes, flow rate decay, and the reference data of similar ages. Adjusted to age, BMI, and number of hospitalizations prior to the tests, values were correlated with the cough indices.

RESULTS

Cough peak-flow (C-PF) was propagated within 90 ± 20 ms compared with peak expiratory flow (PEF > 200 ms). C-PF measured values were higher than expiratory peak-flow measured values (3.27 ± 1.53 L/s versus 3.02 ± 1.52 L/s, respectively, but C-PF (%predicted) values were significantly lower than expiratory peak-flow (%predicted) (46 ± 15 versus 68 ± 20 %predicted, respectively, p < 0.002). The number of spikes/maneuver was low when compared with reference (2.0 ± 0.8 versus 6-12 spikes) and cough vital-capacity was lower than expiratory vital capacity (0.95 ± 0.43 versus 1.03 ± 0.47; p < 0.01). Inefficient C-PF was more prevalent in patients suffering from recurrent respiratory illness. The length of wheelchair confinement duration mostly influenced the C-VC level.

CONCLUSIONS

The cough flow-volume curve can be applied as a method to follow cough ability in patients with A-T who showed a significantly reduced cough capacity. Further studies are needed to establish if the findings may aid decisions regarding cough assistance.

Effects of home-based respiratory muscle training in children and adolescents with chronic lung disease

OBJECTIVE

Respiratory muscle weakness is a functional repercussion of chronic lung disease (CLD). The objective of this study was to assess the effects of home-based respiratory muscle training (RMT) in children and adolescents with CLD or neuromuscular disease (NMD).

METHODS

This was a quasi-experimental study involving children and adolescents with CLD or NMD. Before and after 6 months of home-based RMT, we measured respiratory muscle strength (MIP and MEP), PEF, and peak cough flow (PCF). We made statistical comparisons between the pre-RMT and post-RMT values, as well as evaluating the correlation between the duration and effect of RMT.

RESULTS

The study included 29 patients, with a mean age of 12 years (range, 5-17 years), of whom 18 (62.1%) were male. The CLD group comprised 11 patients (37.9%), and the NMD group comprised 18 (62.1%). The mean duration of the RMT was 60 weeks (range, 46-90 weeks) in the CLD group and 39 weeks (range, 24-89 weeks) in the NMD group. In comparison with the pre-RMT values, the post-RMT values for MIP and MEP were significantly higher in both groups, whereas those for PEF and PCF were significantly higher only in the NMD group. We found no correlation between the duration and the effect of RMT.

CONCLUSIONS

Home-based RMT appears to be an effective strategy for increasing respiratory muscle strength in children and adolescents with CLD or NMD, although it increased the ability to cough effectively only in those with NMD.

Outcome reliability in non-ambulatory boys/men with Duchenne muscular dystrophy

INTRODUCTION

Therapeutic trials in Duchenne muscular dystrophy (DMD) often exclude non-ambulatory individuals. Here we establish optimal and reliable assessments in a multicenter trial.

METHODS

Non-ambulatory boys/men with DMD (N = 91; 16.7 ± 4.5 years of age) were assessed by trained clinical evaluators. Feasibility (percentage completing task) and reliability [intraclass correlation coefficients (ICCs) between morning and afternoon tests] were measured.

RESULTS

Forced vital capacity (FVC), assessed in all subjects, showed a mean of 47.8 ± 22% predicted (ICC 0.98). Brooke Upper Extremity Functional Rating (Brooke) and Egen Klassifikation (EK) scales in 100% of subjects showed ICCs ranging from 0.93 to 0.99. Manual muscle testing, range of motion, 9-hole peg test, and Jebsen-Taylor Hand Function Test (JHFT) demonstrated varied feasibility (99% to 70%), with ICCs ranging from 0.99 to 0.64. We found beneficial effects of different forms of corticosteroids for the Brooke scale, percent predicted FVC, and hand and finger strength.

CONCLUSIONS

Reliable assessment of non-ambulatory boys/men with DMD is possible. Clinical trials will have to consider corticosteroid use.

Test-retest reliability of expiratory abdominal compression with a handheld dynamometer in patients with prolonged mechanical ventilation

[Purpose] The present study aimed to examine the test-retest reliability of expiratory abdominal compression with a handheld dynamometer in patients with prolonged mechanical ventilation. [Subjects and Methods] We recruited 18 patients with prolonged mechanical ventilation. All patients had impaired consciousness. The mode of the ventilator was synchronized intermittent mandatory ventilation. The abdomen above the navel was vertically compressed using a handheld dynamometer in synchronization with expiration. Expiratory abdominal compression was performed two times. We measured the tidal volume during expiratory abdominal compression. There was an interval of 5 minutes between the first and second measurements. Intraclass correlation coefficient (ICC) and Bland-Altman analysis were performed to examine the test-retest reliability of expiratory abdominal compression with a handheld dynamometer. [Results] The test-retest reliability of expiratory abdominal compression was excellent (ICC(1, 1): 0.987). Bland-Altman analysis showed that there was no fixed bias and no proportional bias. [Conclusion] The findings of this study suggest that expiratory abdominal compression with a handheld dynamometer is reliable and useful for patients with respiratory failure and prolonged mechanical ventilation.

Non-pharmaceutical management of respiratory morbidity in children with severe global developmental delay

BACKGROUND

Children with severe global developmental delay (SGDD) have significant intellectual disability and severe motor impairment; they are extremely limited in their functional movement and are dependent upon others for all activities of daily living. SGDD does not directly cause lung dysfunction, but the combination of immobility, weakness, skeletal deformity and parenchymal damage from aspiration can lead to significant prevalence of respiratory illness. Respiratory pathology is a significant cause of morbidity and mortality for children with SGDD; it can result in frequent hospital admissions and impacts upon quality of life. Although many treatment approaches are available, there currently exists no comprehensive review of the literature to inform best practice. A broad range of treatment options exist; to focus the scope of this review and allow in-depth analysis, we have excluded pharmaceutical interventions.

OBJECTIVES

To assess the effects of non-pharmaceutical treatment modalities for the management of respiratory morbidity in children with severe global developmental delay.

SEARCH METHODS

We conducted comprehensive searches of the following databases from inception to November 2013: the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE, the Allied and Complementary Medicine Database (AMED) and the Cumulative Index to Nursing and Allied Health Literature (CINAHL). We searched the Web of Science and clinical trials registries for grey literature and for planned, ongoing and unpublished trials. We checked the reference lists of all primary included studies for additional relevant references.

SELECTION CRITERIA

Randomised controlled trials, controlled trials and cohort studies of children up to 18 years of age with a diagnosis of severe neurological impairment and respiratory morbidity were included. Studies of airways clearance techniques, suction, assisted coughing, non-invasive ventilation, tracheostomy and postural management were eligible for inclusion.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures as expected by The Cochrane Collaboration. As the result of heterogeneity, we could not perform meta-analysis. We have therefore presented our results using a narrative approach.

MAIN RESULTS

Fifteen studies were included in the review. Studies included children with a range of severe neurological impairments in differing settings, for example, home and critical care. Several different treatment modalities were assessed, and a wide range of outcome measures were used. Most studies used a non-randomised design and included small sample groups. Only four randomised controlled trials were identified. Non-randomised design, lack of information about how participants were selected and who completed outcome measures and incomplete reporting led to high or unclear risk of bias in many studies. Results from low-quality studies suggest that use of non-invasive ventilation, mechanically assisted coughing, high-frequency chest wall oscillation (HFCWO), positive expiratory pressure and supportive seating may confer potential benefits. No serious adverse effects were reported for ventilatory support or airway clearance interventions other than one incident in a clinically unstable child following mechanically assisted coughing. Night-time positioning equipment and spinal bracing were shown to have a potentially negative effect for some participants. However, these findings must be considered as tentative and require testing in future randomised trials.

AUTHORS' CONCLUSIONS

This review found no high-quality evidence for any single intervention for the management of respiratory morbidity in children with severe global developmental delay. Our search yielded data on a wide range of interventions of interest. Significant differences in study design and in outcome measures precluded the possibility of meta-analysis. No conclusions on efficacy or safety of interventions for respiratory morbidity in children with severe global developmental delay can be made based upon the findings of this review.A co-ordinated approach to future research is vital to ensure that high-quality evidence becomes available to guide treatment for this vulnerable patient group.

Determinants of cough efficiency in Duchenne muscular dystrophy

OBJECTIVE

With the progression of Duchenne muscular dystrophy (DMD) cough becomes inefficient leading to recurrent chest infections. Several factors determine the effectiveness of cough in DMD patients. The aim of this study was to investigate how weakened inspiratory muscles alter operating lung and thoraco-abdominal volumes and whether they contribute to cough efficiency.

PATIENTS AND METHODS

Pulmonary function, respiratory muscle strength, and peak cough flow (PCF) were assessed in 36 DMD patients (age 17.0 ± 5.0). Total and compartmental chest wall volumes were measured by Opto-Electronic Plethysmography in the DMD patients and 15 age-matched controls during quiet breathing and maximal voluntary cough maneuvers. The DMD population was divided into three groups: PCF < 160 L/min (inefficient cough), PCF > 270 L/min (efficient cough), and 160 < PCF < 270 L/min (intermediate cough efficiency).

RESULTS

During the inspiration preceding cough, patients with efficient cough presented normal volume variations whereas patients with intermediate cough efficiency showed low abdominal volume variation (P < 0.01). Patients with inefficient cough were characterized by reduced total (P < 0.05) and compartmental (ribcage: P < 0.01; abdomen: P < 0.001) chest wall volumes during the inspiration preceding cough and reduced abdominal contribution to tidal volume during quiet breathing (ΔVAB (%VT), P < 0.001). ROC analysis revealed that among all spirometric, respiratory muscle strength and chest wall parameters ΔVAB (%VT ) was the best discriminator between inefficient and efficient cough.

CONCLUSIONS

Inefficient cough in DMD is associated to reduced operating lung and chest wall volume secondary to weakened inspiratory muscles. Abdominal contribution to tidal volume during spontaneous breathing represents a non-volitional and noninvasive index able to discriminate efficient and inefficient cough.

Respiratory management strategies for Duchenne muscular dystrophy: practice variation amongst Canadian sub-specialists

PURPOSE

Respiratory management of Duchenne muscular dystrophy (DMD) is not well studied and may vary across centers and practitioners. Our objective was to describe and compare the respiratory management practices of Canadian Pediatric Respirologists and Neuromuscular specialists for children with DMD.

METHODS

A web-based survey was sent to all 56 practicing Canadian Pediatric Respirologists and to all 24 members of the Canadian Pediatric Neuromuscular Group (CPNG) who follow children with neuromuscular diseases. The survey included 28 questions about timing and indications for respiratory consultation, sleep disordered breathing (SDB) assessments, and treatments.

RESULTS

Thirty eight (68%) pediatric respirologists and 17 (71%) CPNG members responded. Respirologists provide initial consultation after a patient's first admission to hospital with respiratory complications (14/38, 37%) and when symptoms of SDB are present (14/38, 37%). Half of the CPNG members request initial Respirology consultation at the time of DMD diagnosis. Both groups request routine pulmonary function tests. Ninety-six percent of respirologists use maximal inspiratory (MIP) and expiratory pressures (MEP) to assess respiratory muscle strength, whereas 82% of CPNG members additionally use peak cough flow. Assessment for SDB is requested by both groups when pulmonary function is abnormal or patients are symptomatic. Respirologists favor polysomnography, whereas CPNG members use overnight pulse oximetry. Nocturnal non-invasive ventilation and lung volume recruitment (LVR) are used in a minority of patients.

CONCLUSIONS

Respirologists and CPNG members provide similar respiratory management of DMD patients, but differ in timing of consultation and choice of tests for pulmonary function and SDB. Canadian practices differ from the American Thoracic Society and Centre for Disease Control guidelines.

Establishing clinical end points of respiratory function in large animals for clinical translation

Respiratory dysfunction due progressive weakness of the respiratory muscles, particularly the diaphragm, is a major cause of death in the neuromuscular disease (NMD) X-linked myotubular myopathy (XLMTM). Methods of respiratory assessment in patients are often difficult, especially in those who are mechanically ventilated. The naturally occuring XLMTM dog model exhibits a phenotype similar to that in patients and can be used to determine quantitative descriptions of dysfunction as clinical endpoints for treatment and the development of new therapies. In experiments using respiratory impedance plethysmography (RIP), XLMTM dogs challenged with the respiratory stimulant doxapram displayed significant changes indicative of diaphragmatic weakness.

Value of preoperative pulmonary function test in flaccid neuromuscular scoliosis surgery

STUDY DESIGN

Retrospective study.

OBJECTIVE

To evaluate the prognostic value of preoperative pulmonary function test (PFT) for postoperative pulmonary complications and to identify the operability associated with severely decreased forced vital capacity (FVC) (<30%) status in flaccid neuromuscular scoliosis.

SUMMARY OF BACKGROUND DATA

The preoperative PFT, especially more than 30% FVC, is known as a critical factor for the operability of flaccid neuromuscular scoliosis. But only one study reported that patients with pre-existing respiratory failure on nocturnal noninvasive ventilation can undergo an operation for deformity correction without mortality and severe complications.

METHODS

A total of 74 patients (45 male and 29 female) presented with flaccid neuromuscular scoliosis. For all patients, preoperative PFTs were evaluated and subdivided into three groups (<30% FVC, 30%-50% FVC, and >50% FVC). Then postoperative pulmonary complications, pneumothorax, pneumonia, atelectasis, prolonged ventilator care in the intensive care unit (more than 72 hours), and postoperative tracheostomy were evaluated.

RESULTS

Among these patients, 59 had muscular dystrophy; 5, spinal muscular atrophy; 2, cerebral palsy; and 8, others. The mean age at surgery was 16.8 years (range, 5-32 years). The mean preoperative Cobb angle was 54.6° (16°-135°). The overall postoperative pulmonary complication rate was 31% (23 complications in 74 patients). The less than 30% FVC group had 6 complications among 18 patients; the 30% to 50% FVC group had 7 complications among 18 patients; and the more than 50% FVC group had 10 complications among 38 patients. There were no deaths during the perioperative period. There is no statistical difference between the three groups (P = 0.6195).

CONCLUSION

Patients with flaccid neuromuscular scoliosis can undergo an operation for deformity correction regardless of the severely decreased pulmonary function.

Bone mineral density and respiratory muscle strength in male individuals with mental retardation (with and without Down Syndrome)

The purpose of this study was to assess the respiratory muscle strength (RMS) in individuals with mental retardation (MR), with or without Down Syndrome (DS), and its association with bone mineral density (BMD). Forty-five male individuals (15 with DS, 15 with mental retardation (MR) and 15 apparently healthy controls), aged 20-35, participated in this study. Subject assessment included pulmonary function tests, RMS (maximal inspiratory pressure, MIP, and maximal expiratory pressure, MEP) and BMD of the second and fourth lumbar vertebrae. ANOVA was used to test differences amongst groups. Tukey post hoc test was utilized when significant differences were detected with ANOVA. Bivariate correlation for BMD and respiratory muscle strength was calculated with Pearson's coefficient of correlation. Individuals with MR, both with and without DS, have lower FEV1, FVC, MIP and MEP (p<0.001) compared to controls. Individuals with DS also had lower BMD, which was associated with lower MIP and MEP. Hypotonia, sedentary lifestyle and obesity are factors that may explain lower MIP and MEP in DS. Strategies to increase RMS could decrease the risk of osteoporosis in the DS population.

Aplicação clínica do pico de fluxo da tosse: uma revisão de literatura

INTRODUÇÃO: A tosse é responsável pela manutenção da via aérea livre de secreção e corpos estranhos. O pico de fluxo da tosse (PFT) é o fluxo expirado máximo medido durante uma manobra de tosse por meio de um peak flow meter. A eficácia da tosse depende da magnitude do pico de fluxo. Técnicas de insuflação assistida e de assistência manual à tosse podem aumentar a sua eficácia. Um PFT mínimo de 160 L/min foi relatado por alguns autores como necessário para manutenção da clearance brônquica e desmame da ventilação mecânica. OBJETIVO:Realizar uma revisão de literatura sobre a utilização do pico de fluxo da tosse na avaliação da eficácia da tosse em diferentes situações clínicas. MÉTODOS: Foi utilizado o descritor peak cough flow, durante a pesquisa realizada nas bases de dados Medline, SciELO e LILACS. RESULTADOS:Foi encontrado um total de 36 artigos, sendo 31 selecionados para leitura. Foram selecionados os artigos em português, espanhol ou inglês. CONCLUSÃO:O PFT vem sendo cada vez mais utilizado na avaliação dos doentes neuromusculares e também em outras situações clínicas.

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.

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.