Management of respiratory disease in children with muscular weakness

SYMPOSIUM: NEUROLOGY

Management of respiratory disease in children with muscular weakness Robert Ross Russell

manner to NMD, the impact on respiratory health is similar. As with NMD, respiratory factors are the leading cause of death among CP patients, and careful consideration of respiratory care can improve outcomes as well. This article will predominately focus on patients with NMD, but will also reflect on the problems seen in CP. Muscle weakness caused by rare cases including spinal cord injury or GuillaineBarre syndrome will not be discussed specifically, although the principles that are described here remain the same.

Abstract

Pathophysiology, risk factors and problems

R Abusamra

Children with chronic muscular weakness from any cause are prone to develop varying degrees and patterns of respiratory muscle weakness. This leads to ineffective cough, atelectasis, pneumonia, restrictive pulmonary disease and eventually respiratory failure. Over the past 20 years there have been improvements in clinical care of children with muscular weakness, including improved monitoring of lung function and hypoventilation during sleep, coordinated multidisciplinary respiratory care, physiotherapy and introduction of non-invasive ventilation. This article reviews the current knowledge base and the evidence for management of children and provides practical advice for paediatricians.

The range of presentations seen with NMD is wide, and it is beyond the scope of this article to review them in detail. However, it is very important to recognise the variability in the age of onset, disease severity and the pattern of disease progression that may occur. A brief summary is shown in Table 1. The most common neuromuscular childhood diseases are Duchenne muscular dystrophy (DMD), spinal muscular atrophy (SMA) and congenital muscular disorders (CMD). DMD typically presents with an early onset and is often associated with some developmental delay. The disease is progressive, ultimately involving the heart muscle. Scoliosis develops in w70e90% patients and current life expectancy is in the mid-20s. By contrast, SMA can vary significantly in severity: infants with Type I SMA usually die within two years, but for Type III SMA, life expectancy extends into adulthood. Scoliosis is universal in Types I and II, but there is no cardiac involvement. Children with CMD typically present early and it can be associated with significant weakness. However, progress of this weakness is usually slow or absent, and if present may occur in late childhood. Despite these differences, the respiratory muscles are rarely spared in neuromuscular diseases even if the type of muscle involvement, severity and time course varies greatly between these three different diseases. Respiratory symptoms are, therefore, common and can occur at several different levels. We have grouped these respiratory complications into three categories: issues with the upper airway (airway protection, swallowing and obstructive sleep problems), ventilation problems (respiratory muscles, lung compliance, gas exchange) and infection.

Keywords cerebral palsy; children; neuromuscular disease; respiratory

Introduction Children with muscle weakness include a large and heterogeneous group of patients, including those with neuromuscular disease (NMD), cerebral palsy or developmental delay, spinal injury and other rarer conditions. Muscle weakness often has a very significant effect on respiratory health and as a result these children require regular structured assessments. NMD has a prevalence of 1 in 3000 in the UK population. Although, respiratory failure is the most common cause of death in this group, several factors, including the age of onset, disease severity and the rate of disease progression may vary for each individual. There has been considerable progress in medical care which has increased both duration and quality of life in these patients. Notable recent improvements include adjuncts to assist airway clearance, and the prompt evaluation of respiratory function by multidisciplinary teams. Cerebral palsy (CP) is more common in the population, with a prevalence of approximately 2 per 1000 children. It is associated with prematurity and may be accompanied with concomitant developmental delay. Although CP and developmental delay affect the muscles and the airway protection in a different

Upper airway problems One of the major dangers in children suffering from respiratory weakness is their reduced ability to protect their airways. Coughing, gagging and swallowing reflexes may all be impaired, increasing the risk of aspiration. In order to produce an effective cough, a deep breath (inspiratory muscles) has to be followed by a maximal contraction of the expiratory muscles, with initial glottis closure and then opening (oropharyngeal muscles), which generates an expiratory flow capable of eliminating secretions. All three muscle groups may be weak, leading to reduced airway clearance. Over time, the continuous presence of pooled secretions in the oropharynx may also lead to a reduced cough stimulus. Impairment of the oropharyngeal muscles, in addition to contributing to ineffective cough, will cause phonation and swallowing disorders with a risk of broncho-aspiration that may lead to acute respiratory failure.

R Abusamra MBBS MRCPCH is National (GRID) Trainee in Paediatric Respiratory Medicine, Department of Paediatrics, Cambridge University Hospitals NHS Foundation Trust, Cambridge, UK. Conflict of interest: none declared. Robert Ross Russell MA MB BChir MD FRCP FRCPCH FHEA is Consultant in Paediatric Care and Respiratory Paediatrics in the Department of Paediatrics, Cambridge University Hospitals NHS Foundation Trust, Addenbrooke’s Hospital, Cambridge, UK. Conflict of interest: none declared.

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Condition

Secretion clearance difficulty

Recurrent pneumonia

Progression

Disease-specific features

All by 2 years w40% in childhood Rare in childhood All by 6 months

Marked Early Rare in childhood Marked

All w25% in first 5 years Rare in childhood All

Rapid Slow Slow Rapid in first year, then slows

All require full-time respiratory support

After loss of ambulation

After loss of ambulation

Late

When onset <20 years

With infantile onset

With infantile onset

Slow

Any age depending on severity

Any age depending on severity Infrequent

Slow

All require full-time respiratory support Cardiomyopathy usually occurs after respiratory problems but may precede them Severe infantile onset type is frequently associated with sensorineural deafness

Ullrich

70% in adolescence

Any age depending on severity Mild

Rigid spine muscular dystrophy

Early while ambulation preserved

Mild

Infrequent

Uncommon except in severe recessive type Early while ambulation preserved Early in severe neonatal form, mild later onset form may develop early while ambulation preserved 85% in serve X-linked form

Uncommon

Uncommon

Slow

In severe form

In severe form

Slow

In severe form

In severe form

Slow

Ophthalmoplegia, rare coagulopathy and liver haemorrhage

Depends on genotype

Uncommon

Uncommon

Common in severe congenital onset, usually improves

Common in severe congenital onset

Common in severe congenital onset

Initial improvement, later slow deterioration

Prominent learning difficulty, somnolence, central hypoventilation

Uncommon Often in neonatal period, may occur during inter-current illnesses

Uncommon Especially during inter-current illnesses

Uncommon Possible if weakness severe and persistent

Proximal contractures with marked distal laxity Hypoventilation may occur in ambulant children with relatively preserved vital capacity

Congenital myopathy Central core Minicore Nemaline

Myotubular

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Fiber type disproportion Myotonic dystrophy Myotonic dystrophy 1

Myotonic dystrophy 2 Congenital myasthenic syndromes

Susceptible to malignant hyperthermia

Weakness may fluctuate, episodic apnoea in some. Congenital stridor in those with D0K7 mutations

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SMA Type 1 Type 2 Type 3 SMA with respiratory distress type 1 DMD/severe childhood onset limb-girdle muscular dystrophy Facioscapulohumeral muscular dystrophy Congenital muscular dystrophy All types

Respiratory failure

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Respiratory features of neuromuscular diseases

Variable relationship between motor and respiratory progression

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Ventilation problems Spontaneous ventilation is controlled by the central respiratory drive. This controls the balance between respiratory muscle performance and respiratory load, which is determined by lung, thoracic and airway mechanics. Weakness of the respiratory muscles is the main cause of the ventilator imbalance observed in NMD. Progressive weakness in the inspiratory muscles (mainly the diaphragm) leads to a respiratory pattern with low tidal volumes and increased frequency (superficial respiration). There is also an increase in respiratory load which is often due to thoracic scoliosis and the progressive ‘stiffening’ of the rib cage as well as micro-atelectasis of the lung due to insufficient thoracic movements. Inspiratory and expiratory muscle strength mostly decrease in parallel, but when diaphragm strength is preserved expiratory muscle weakness may predominate e.g. in spinal muscular atrophy. Ventilatory drive is increased with mild to moderate respiratory muscle weakness, leading to hyperventilation, a normal or elevated pH, and a reduced arterial tension of carbon dioxide (pCO2). As respiratory muscles weaken further, pCO2 increases. Hypoxaemia occurs in advanced disease and may be caused by alveolar hypoventilation, retained secretions and mucous plugs, in addition to pneumonia and atelectasis. Sleep is associated with a number of physiological changes, in particular, during REM sleep. In REM sleep there is muscle weakness with reduced central respiratory drive and chemoreceptor sensitivity. Ventilation/perfusion mismatch increases, and there is an increase in airflow resistance and a fall in functional residual capacity (FRC). All these changes explain a physiological decrease in spot arterial oxygen saturation measured by pulse oximetry (SpO2) of approximately 2e3% and an increase in partial arterial carbon dioxide pressure (PaCO2) around 3e5 mm Hg during normal sleep. Sleep disordered breathing is likely when vital capacity falls to less than 60%. Nocturnal alveolar hypoventilation is more significant in patients with NMDs which may lead to complications such as hypersomnia, tiredness on waking and a morning headache. Together with alteration in the respiratory pattern and ventilation control, sustained nocturnal hypoventilation may lead to progressive diurnal hypoventilation. However, this may be acute in the case of an ineffective cough or broncho-aspiration caused by secretion retention during a secondary respiratory infection. Infection problems The risk of respiratory infection is elevated in children with muscle weakness due to several factors, including reduced airway protection with increased risk of aspiration and ineffective secretion clearance. Respiratory tract infections further increase the work of breathing, as well as the metabolic demand, which together may cause a greater imbalance between respiratory muscle capacity and respiratory load. Lower respiratory tract infections (LRTIs) may precipitate rapid and unexpected

Table 1

From Thorax 2012;67:i1ei40. http://dx.doi.org/10.1136/thoraxjnl-2012-201964, with permission.

DMD, Duchenne muscular dystrophy; SMA, spinal muscular atrophy.

Infantile onset Infantile onset Pompe

With severe early onset With severe early onset

With severe early onset, especially with GDAP1 mutation Infantile onset, may be early in later onset while ambulation preserved CharcoteMarieeTooth

Possible Possible Common Mitochondrial myopathy

The upper airway can also be at risk during sleep. REM sleep is associated with muscle atonia (except for the diaphragm), and in patients with muscle weakness, there is a greater incidence of obstructive sleep apnoea. In addition, other problems with ventilation are also more common during sleep (see below).

Infantile rapid, late onset slow

Acute deterioration possible

Stridor, especially with GDAP1 mutation

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respiratory decompensation. LRTIs may also add further to lung damage, causing the development of bronchiectasis, which in turn, could lead to a greater risk of infection and subsequent erosion of the respiratory reserve.

between the inspiratory muscles and the diaphragm is thought to be a strategy of fatigue avoidance. Lung function and respiratory muscle function parameters Pulmonary function tests in patients with neuromuscular disease are characterized by a pattern of restriction as a result of variable combinations of reduced inspiratory muscle strength, the presence of thoracic scoliosis and reduced chest wall and pulmonary compliance. There are different methods and tests to evaluate lung function and respiratory muscle strength in these patients. These tests are classified as either invasive or non-invasive (Table 2) or volitional and non-volitional.

Assessment Clinical assessment of respiratory health should be part of every medical consultation for children with muscular weakness and should be directed towards identifying progressive muscle weakness, ability to cope with respiratory infection, aspiration, progression of scoliosis and sleep-disordered breathing. Formal respiratory assessment is best carried out in a multidisciplinary fashion by a team including a respiratory physician, chest physiotherapist, respiratory physiologist and dietitian. Evaluation is based on a good respiratory history and examination coupled with non-invasive tests, such as the measurement of lung volumes, spirometry and the maximal static pressures, although these may be difficult or impossible to obtain in some young children. Formal assessment prior to surgery is also important. Anaesthesia (especially if prolonged, such as for scoliosis surgery) can unmask incipient respiratory failure. Subsequently, the risks of post-operative ventilation need to be considered, but may be difficult to quantify. Symptoms to be explored include aspects of airway protection, as well as direct features of breathlessness. Airway protection symptoms include dysarthria, dysphagia, difficulty chewing, choking and an ineffective cough, which all suggest an involvement of the oro-pharyngeal muscles and may cause excessive drooling, aspiration and dysphonia. Symptoms of breathlessness include malaise, lethargy and difficulty concentrating which may precede later conventional symptoms of dyspnoea and orthopnoea. Dyspnoea with supination, bending, or immersion in water (e.g. entering a swimming pool) is suggestive of diaphragmatic weakness. A history of recurrent upper and lower respiratory tract infection with frequent hospital admission, especially admission to intensive care, can be a marker of disease severity. The technique of counting words after maximum inspiration is associated with hypoventilation (50 is normal and less than 15 is severe), but has not been validated. Symptoms associated with sleep include hypersomnia and tiredness on waking, as well as malaise, drowsiness and morning headache, suggesting sleep hypoventilation. Due to the impaired mobility of the patients, symptoms of hypoventilation may initially be subtle and depend on the pattern of respiratory muscle weakness. The upper and lower airways, respiratory rates, breathing patterns and expiratory sounds should be examined. Thoracoabdominal incoordination may occur in two patterns. Weakness of the diaphragm (e.g. in SMARD) may cause an inward movement of the abdomen and expansion of the ribcage during inspiration. Conversely, a weak chest wall may cause the opposite with outward abdominal movement and thoracic wall collapse; together with rapid shallow breathing either feature may indicate respiratory weakness. Respiratory alternans may occur when both types of thoraco-abdominal incoordination exist in the same patient. This alternation of the respiratory load

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Non-invasive tests There are three types of non-invasive tests including assessment of flow and volume measurement, breathing pattern and pressure tests. Measurement of flows and volumes (FVC, FEV1, RV, FRC, TLC) constitute the first type of non-invasive test. The characteristic finding in NMD is a restrictive ventilatory defect, with a reduced forced vital capacity (FVC) and total lung capacity (TLC), normal or low functional residual capacity (FRC) and an increased residual volume (RV), due to weakness of the expiratory muscles. An elevated RV may be one of the earliest lung function abnormalities detected with expiratory muscle weakness. The flow/volume loop trace shows slow expiration with reduced peak flow, ending abruptly. The inspiratory flow is also reduced. The strength of the respiratory muscles must be severely impaired (by as much as 50%) before any significant reduction in lung volumes is found. In subjects with diaphragm weakness, VC falls when the patient is supine, although this fall must exceed 25% to be unequivocally abnormal. Peak cough flow can be measured in cooperative children over the age of 6 years. It is an easy test to perform, but thresholds associated with an impaired coughing ability are uncertain for children. Values less than 270 L/minute in children aged 10 years and above suggest reduced cough power, and values less than 160 L/minute are associated with increased frequency of chest infections. The second type of non-invasive test, the pattern of breathing, can be informative. The rapid shallow breathing index (RSBI) is calculated by measuring the breathing rate (fR) and tidal volume (VT). It is increased in respiratory failure and in adults has been shown to predict both need for ventilation and success of extubation. The rapid shallow breathing index (fR/VT) is a marker of increased workload (rather than respiratory weakness). As well as measuring it directly, tidal volume (VT) can be measured using respiratory inductive plethysmography. The technique can be used to assess changes in the cross-sectional area of the chest (and by implication volume changes) by measuring changes in electrical impedance. Clinically this can also be useful in assessing thoraco-abdominal asynchrony. Optical techniques, such as Structured Light Plethysmography (SLP) or Optoelectronic plethysmography (OEP) can evaluate ventilation through an external video measurement of the chest wall surface motion. This technique has been used to show normalisation of thoracoabdominal movements in children during non-invasive ventilation (NIV) and can also separate out abdominal and thoracic

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Different respiratory muscle tests used in children Specific type of muscle tested

None invasive

Invasive

Diaphragm

Inspiratory

Expiratory

Inspiratory & expiratory

TLC Pimax Sniff nasal inspiratory pressure RV Pemax Peak expiratory flow Cough peak flow VC Crying mouth pressure

Breathing pattern with Poes & Pgas Crying Pdi Tension time index TTdi Tension time index TToes

Pgas during a maximal cough

Poes & Pdi during a maximal sniff

Table 2

Sleep assessment Overnight sleep monitoring is used to identify patients who have nocturnal hypoventilation or other sleep disturbances. This tends to occur in the later stages of NMD. The combination of reduced muscle tone and reduced CO2 sensitivity during sleep can give rise to obstructive sleep apnoea, as well as hypoxia and hypercarbia. Night-time hypoxia usually precedes night-time hypercarbia and both tend to occur before daytime hypoventilation. Indications for sleep studies in patients with NMD include patients with an FVC below 60% predicted or those who are wheelchair bound. Other groups at greater risk of sleep problems include infants with weakness, children with symptoms of obstructive sleep apnoea or night-time hypoventilation, patients with diaphragmatic weakness and the presence of ‘rigid spine’ syndrome. There are three main types of sleep assessment. Overnight oximetry is often used to screen for sleep disordered breathing in children with neuromuscular disease. Whilst a normal trace in a child who has slept well usually excludes a significant problem, arterial saturation within the normal range can occasionally be seen in children with mild obstructive sleep apnoea/hypopnea and can be accompanied by hypercapnia in children using CPAP or NIV. Respiratory polygraphy or cardiorespiratory sleep studies are more detailed. Patients are monitored through a number of additional channels, such as ECG, thoraco-abdominal breathing patterns, nasal flow and video monitoring. Oxycapnography includes the measurement of carbon dioxide tension, which can be measured using end-tidal or transcutaneous devices, which correlate well with each other. Although these studies provide more comprehensive information and can distinguish OSA from hypoventilation, they usually require hospital admission and are often poorly tolerated, which may interfere with the quality of the overall study. Lastly patients may undergo polysomnography (PSG). In full PSG, continuous EEG, electromyogram and electro-oculogram are also measured. This type of study allows accurate sleep staging, gives information about sleep efficiency and sleep quality as well as detailed characterisation of respiratory patterns

contribution to breathing, which may be of value in predicting nocturnal hypoxaemia in DMD patients. Lastly, diaphragmatic ultrasound can be used for evaluation of the structure and dynamic function of the diaphragm. Measurements of pressures are the third type of non-invasive test for respiratory function. Maximal static pressures are generated when breathing against occluded airways during maximal forced inspiratory and expiratory effort. A small leak on the mouthpiece is necessary to prevent glottic closure and artificially high maximal pressure values. Maximal inspiratory pressure (Pimax) measured at RV reflects the pressure developed by the inspiratory muscles coupled with the outward recoil pressure of the respiratory system present at this lung volume. In contrast, Pimax measured at FRC represents solely the inspiratory muscles. Maximal static expiratory pressure is measured when the expiratory muscles are optimally stretched after a full inspiration to near TLC. Sniff nasal inspiratory pressure (SNIP) is easier to perform than maximal static pressures, and the majority of children older than 4 years are able to perform sniff efforts. In healthy subjects, the pressure measured in the mouth, nasopharynx and the nose during a sniff is closely related to that in the oesophagus. This technique provides a reasonable estimate of the inspiratory muscle strength, and a pressure greater than 60 cm H2O in women and 70 cm H2O in men excludes significant respiratory muscle weakness. SNIP may underestimate inspiratory muscle strength in case of nasal obstruction due to adenoids or nasal polyps, or in patients with severe respiratory muscle weakness.

Invasive tests There are two main types of invasive tests that can be useful. Firstly a capillary or arterial blood gas may show hypoxia e which can be associated with a reduced CO2 level in early disease. More commonly a degree of hypercarbia is found with a compensating rise in bicarbonate and fall in chloride. The second type of invasive test is measurement of transdiaphragmatic pressure. For this measurement the placement of oesophageal and gastric balloons or pressure transducers is needed which allows the measurement of transdiaphragmatic pressure (Pdi), and crying or sniff Pdi.

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and interventional categories, although a number of treatments (such as physiotherapy or antibiotics) may have roles in both categories.

and abnormalities. For these reasons, PSG remains the gold standard for diagnosing nocturnal hypoventilation, even though it is time-consuming, expensive, and its availability is limited in many settings.

General care Nutrition is important. Optimal nutrition can improve muscle strength, which in turn reduces the risk of respiratory muscle fatigue. Equally, prevention of obesity in some children can be difficult due to their inactivity, and this can have harmful outcomes.

Scoliosis assessment Scoliosis is common and will occur in virtually all children with SMA types I and II, and in 70e90% of those with DMD. It is also a common complication of CP, occurring in around 28% of patients. Scoliosis progresses with the adolescent growth spurt and may also progress more rapidly as children transition to permanent wheelchair use. However, the use of steroid therapy and preservation of standing using frames may reduce the severity of scoliosis. Scoliosis surgery is carried out to prevent progression of the curvature. The optimal timing of scoliosis surgery in children is influenced by a number of factors, including, curve progression, sitting comfortably in wheelchair-bound patients, mobility and pain. Outcome data following scoliosis surgery is mixed. There is evidence that the procedure can improve the quality of life, although it may also slow the rate of deterioration of lung function in patients with DMD.

Physiotherapy and other physical support A specialist respiratory physiotherapist should carry out a comprehensive assessment of the child’s respiratory health in order to choose the correct treatment strategy. This assessment should include a full subjective and objective assessment, lung function tests and peak cough flows. The aims of physiotherapy treatment are multi-factorial. It can help prevent atelectasis, improve lung compliance and aid in secretion clearance by improving cough effectiveness. In acute respiratory distress and at end stage lung disease physiotherapy can also aid in decreasing work of breathing. Table 3 gives a list of treatment options that a physiotherapist may consider. The main issue with this group of children is that they are unable to generate enough inspiratory and/or expiratory flow to move secretions and therefore treatments need to address this issue. Children with muscular weakness can have an ineffective cough and manual in/exsufflation has been found to be effective in improving peak cough flow. If a cough assist machine is being used in a home environment then a suction device and oxygen should also be provided. Mucolytics nebulisers such as saline (0.9% or hypertonic) can be used in conjunction with physiotherapy to help loosen secretions although there are no studies to prove the effectiveness of these treatments in this group of patients.

Swallowing and speech assessment The careful assessment of swallowing and airway protection is an important part of the care in any child with NMD. Video fluoroscopy is considered the gold standard in the assessment of dysphagia, since it provides direct information on the oral, pharyngeal and oesophageal phases of swallowing, as well the safety of the oral route (presence of aspiration). A poor swallow, especially if associated with aspiration, raises the difficult question of gastrostomy placement. Whilst this can be an extremely useful adjunct to maintaining good nutrition e an essential aspect of maintaining respiratory function e the loss of the pleasures of eating can be very upsetting for children and families alike. Consideration of the risks (of aspiration) and the benefits (to quality of life) is important in such situations.

Non-invasive ventilation Nocturnal ventilation is recommended in patients who have any of the following: signs or symptoms of hypoventilation (patients with FVC less than 30% predicted are at especially high risk); a baseline SpO2 less than 95% and/or blood or end-tidal CO2 more

Treatment Treatment options for the respiratory aspects of children with NMD are quite limited. In broad terms, they fall into prophylactic

Respiratory physiotherapy methods General

Inspiratory treatments

Expiratory treatments

Positioning Exercise

Unassisted breath stacking Assisted breath stacking using a lung volume recruitment bag Glossopharyngeal breathing Incentive spirometry

Manual assisted cough Cough stimulation

High-frequency chest wall oscillation (HFCWO) Intrapulmonary percussive ventilation (IPV)

Non e invasive ventilation (NIV) Intermittent positive pressure breathing (IPPB) Cough assist: mechanical insufflations/ exsufflation (MIE)

Suctioning Manual techniques (ie percussion & vibrations)

Cough assist: mechanical insufflations/ exsufflation (MIE)

Table 3

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Financial disclosure

than 45 mm Hg while awake; an apnoeaehypopnoea index more than 10 per hour on polysomnography or four or more episodes per hour of desaturation below 92% or falls by 4% or more in SpO2. Diurnal ventilation is indicated if the above symptoms continue in spite of using nocturnal NIV. Invasive ventilation via tracheostomy is also considered a treatment option. The decision to insert a tracheostomy and beginning invasive ventilation needs very careful consideration. There are worldwide variations in practice in term of invasive ventilation for this group of patients. Japanese studies have shown that NIV is associated with an increased lifespan, but in Scandinavia and some European countries, a sequential approach of NIV followed by tracheostomy ventilation is used. Comparisons in outcome are difficult since tracheostomy ventilation is applied later in life and there have been no randomised trials of invasive versus non-invasive ventilation in patients with NMD. Indications for tracheostomy ventilation include: severe bulbar weakness leading to aspiration; upper airway problems limiting delivery of NIV; failure to control ventilation with noninvasive mode; intractable interface problems; near 24-h ventilator dependency, especially in early infancy and lastly the preference of the patient and family.

All authors have no financial relationships relevant to this article to disclose. A FURTHER READING 1 Hull J, Aniapravan R, Chan E, et al. British Thoracic Society guideline for respiratory management of children with neuromuscular weakness. J Br Thorac Soc 2012; 67(suppl 1). n A, Egea C, et al. Guidelines for the management of 2 Farrero E, Anto respiratory complications in patients with neuromuscular disease. Arch Bronconeumol 2013; 49: 306e13. 3 Chan J, Edman JC, Koltai PJ. Obstructive sleep apnea in children. Am Fam Physician 2004; 69: 1147e54. 4 DePalo V. Respiratory muscle evaluation of the patient with neuromuscular disease. Semin Respir Crit Care Med 2002; 23. 5 Bourke SC, Gibson GJ. Sleep and breathing in neuromuscular diseases. Eur Respir J 2002; 19: 1194e201. 6 Mustfa N, Moxham J. Respiratory muscle assessment in motor neurone disease. QJM 2001 Sep; 94: 497e502. 7 Fauroux B, Khirani S. Neuromuscular disease and respiratory physiology in children: putting lung function into perspective. Respirology 2014; 19: 782e91. 8 Suk KS, Lee BH, Lee HM, et al. Functional outcomes in Duchenne muscular dystrophy scoliosis: comparison of the differences between surgical and nonsurgical treatment. J Bone Joint Surg Am 2014; 96: 409e15. 9 Ward S, Chatwin M, Heather S, Simonds AK. Randomised controlled trial of non-invasive ventilation (NIV) for nocturnal hypoventilation in neuromuscular and chest wall disease patients with daytime normocapnia. Thorax 2005; 60: 1019e24. 10 Hughes A, Griffiths M, Ryan MM, Robertson CF, Jones S, Massie J. Changing patterns for the introduction of non-invasive ventilation in children with neuromuscular disease. Internet J Pulm Med 2014; 16.

Medications Inhalation of mucolytics, normal saline or hypertonic saline may assist secretion clearance although no studies have evaluated the effects of inhaled therapies on secretion clearance in children with NMD or CP. The use of prophylactic antibiotics is frequent, but not evidence based in children with NMD or CP. However, it is not unreasonable to extrapolate evidence from other groups of children with difficulty handling secretion clearance and a tendency of recurrent respiratory infection such as in CF patients. Studies in CF populations indicate that prophylactic antibiotics may reduce the frequency of respiratory exacerbation. Macrolides such as Azithromycin have both direct antibacterial and anti-inflammatory properties in addition to particular pharmacokinetic and bioavailability properties that make it useful for prophylaxis treatment with few side effects. Patients may become colonised with organisms such as Pseudomonas aeruginosa, and in these cases, the use of prophylactic inhaled antibiotics such as colomycin or tobramycin should be considered. All children with significant NMD should also be offered a flu jab annually.

Practice points C

C

Conclusion C

Clinical assessment of respiratory health should be part of every medical consultation for children with muscular weakness and should be directed towards identifying progressive muscle weakness, ability to cope with respiratory infection, aspiration, progression of scoliosis and sleep-disordered breathing. It is important to identify respiratory muscle weakness early to allow adequate time for any concern to be addressed. The multidisciplinary clinic answers the complex needs of patients with neuromuscular diseases, by enabling and facilitating the coordination of all procedures, reinforcing good practice, with early and complete care of their needs.

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C

Serial assessment of lung function should be made in all children with muscle weakness disorders, even in the absence of symptoms Difficulty in clearing respiratory secretions requires specific respiratory physiotherapy and occasionally mechanical assistance to achieve effective cough Children with muscular weakness disorders with a history of swallowing difficulties should have a feeding and swallowing assessment by a speech and language therapist NIV should be considered earlier in the course of respiratory deterioration

Acknowledgement Laura Lowndes, Respiratory physiotherapist, Department of Paediatrics, Cambridge University Hospitals NHS Foundation Trust.

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