The assessment and management of the respiratory complications of pediatric neuromuscular diseases

Respiratory performance in Duchenne muscular dystrophy: Clinical manifestations and lessons from animal models

Duchenne muscular dystrophy (DMD) is a fatal genetic neuromuscular disease. Lack of dystrophin in skeletal muscles leads to intrinsic weakness, injury, subsequent degeneration and fibrosis, decreasing contractile function. Dystropathology eventually presents in all inspiratory and expiratory muscles of breathing, severely curtailing their critical function. In people with DMD, premature death is caused by respiratory or cardiac failure. There is an urgent need to develop therapies that improve quality of life and extend life expectancy in DMD. Surprisingly, there is a dearth of information on respiratory control in animal models of DMD, and respiratory outcome measures are often limited or absent in clinical trials. Characterization of respiratory performance in murine and canine models has revealed extensive remodelling of the diaphragm, the major muscle of inspiration. However, significant compensation by extradiaphragmatic muscles of breathing is evident in early disease, contributing to preservation of peak respiratory system performance. Loss of compensation afforded by accessory muscles in advanced disease is ultimately associated with compromised respiratory performance. A new and potentially more translatable murine model of DMD, the D2.mdx mouse, has recently been developed. Respiratory performance in D2.mdx mice is yet to be characterized fully. However, based on histopathological features, D2.mdx mice might serve as useful preclinical models, facilitating the testing of new therapeutics that rescue respiratory function. This review summarizes the pathophysiological mechanisms associated with DMD both in humans and in animal models, with a focus on breathing. We consider the translational value of each model to human DMD and highlight the urgent need for comprehensive characterization of breathing in representative preclinical models to better inform human trials.

Current Update on Role of Hesperidin in Inflammatory Lung Diseases: Chemistry, Pharmacology, and Drug Delivery Approaches

Inflammation is a common feature of many respiratory diseases, such as pneumonia, asthma, pulmonary fibrosis, chronic obstructive pulmonary disease (COPD), lung cancer, acute lung injury, and COVID-19. Flavonoids have demonstrated their anti-inflammatory and antioxidant effects by influencing inflammation at different stages and majorly impacting several respiratory diseases’ onset and development. According to current studies, hesperidin, one of the most abundant polyphenols, can inhibit transcription factors or regulatory enzymes essential for controlling inflammation-linked mediators, including nuclear factor-kappa B (NF-κB), Inducible nitric oxide synthase (iNOS), and cyclooxygenase-2 (COX-2). It also improved cellular antioxidant defences by activating the ERK/Nrf2 signalling pathway. Therefore, this review provides the latest studies on the effect of hesperidin in different respiratory diseases, its pharmacokinetic profile, and innovative drug delivery methods.

[Respiratory physiotherapy in pediatric practice]

Congestion of the upper (URT) and lower respiratory tracts (LRT) is a common symptom in several acute and chronic respiratory diseases that occur in childhood. To eliminate these secretions, airway clearance techniques (ACT) directed to the URT and LRT are frequently prescribed. The rationale for the application of these techniques is the same as in adults, but they need to be adapted to be transposed to children. The physiotherapist will be able to choose among a wide range of techniques, of which the most adequate will depend not only on the age of the child and the indication, but also on the basis of his preferences or habits, as well as those of the child. Upper airway clearance, including nasal irrigation, is now recommended for acute and chronic rhinosinusitis in children. It is also one of the symptomatic treatments recommended for infants with acute bronchiolitis. For LRT clearance, several indications, such as cystic fibrosis, primary ciliary dyskinesia and neuromuscular disease, are now widely advocated. Conversely, other indications, such as for infants with acute viral bronchiolitis, are highly controversial. Thoughtful application of these techniques is lacking in robust and precise tools to objectively assess the presence of bronchial congestion, and to treat it accordingly. Similarly, no precise and reliable evaluation of the effectiveness of these ACTs is available to date. This review is designed to explore the ACTs used by physiotherapists, to provide an overview of their current indications, and to consider complementary approaches.

Respiratory functional and motor control deficits in children with spinal cord injury

Children with spinal cord injury (SCI) are at high risk for developing complications due to respiratory motor control deficits. However, underlying mechanisms of these abnormalities with respect to age, development, and injury characteristics are unclear. To evaluate the effect of SCI and age on respiratory motor control in children with SCI, we compared pulmonary function and respiratory motor control outcome measures in healthy typically developing (TD) children to age-matched children with chronic SCI. We hypothesized that the deficits in respiratory functional performance in children with SCI are due to the abnormal and age-dependent respiratory muscle activation patterns. Fourteen TD (age 7±2 yrs., Mean±SD) and twelve children with SCI (age 6±1 yrs.) were evaluated by assessing Forced Vital Capacity (FVC); Forced Expiratory Volume in 1sec (FEV₁); and respiratory electromyographic activity during maximum inspiratory and maximum expiratory airway pressure measurements (PI_max and PE_max). The results indicate a significant reduction (p<.01) of FVC, FEV₁ and PE_max values in children with SCI compared to TD controls. During PE_max assessment, children with SCI produced significantly decreased (p<.01) activation of respiratory muscles below the neurological level of injury (rectus abdominous and external oblique muscles). In addition, children with SCI had significantly increased (p<.05) compensatory muscle activation above the level of injury (upper trapezius muscle). In the TD group, age, height, and weight significantly (p<.05) contributed towards increase in FVC and FEV₁. In children with SCI, only age was significantly (p<.05) correlated with FVC and FEV₁ values. These findings indicate the degree of SCI-induced respiratory functional and motor control deficits in children are age-dependent.

Recurrent Pneumonia in Children: A Reasoned Diagnostic Approach and a Single Centre Experience

Recurrent pneumonia (RP), i.e., at least two episodes of pneumonia in one year or three episodes ever with intercritical radiographic clearing of densities, occurs in 7.7%–9% of children with community-acquired pneumonia. In RP, the challenge is to discriminate between children with self-limiting or minor problems, that do not require a diagnostic work-up, and those with an underlying disease. The aim of the current review is to discuss a reasoned diagnostic approach to RP in childhood. Particular emphasis has been placed on which children should undergo a diagnostic work-up and which tests should be performed. A pediatric case series is also presented, in order to document a single centre experience of RP. A management algorithm for the approach to children with RP, based on the evidence from a literature review, is proposed. Like all algorithms, it is not meant to replace clinical judgment, but it should drive physicians to adopt a systematic approach to pediatric RP and provide a useful guide to the clinician.

Recurrent lower respiratory tract infections in children: a practical approach to diagnosis

Many children are affected by recurrent lower respiratory tract infections (LRTIs), but the majority of them do not suffer from serious lung or extrapulmonary disease. The challenge for clinicians is to distinguish the recurrent RTIs with self-limiting or minor problems from those with underlying disease. The aim of this review is to describe a practical approach to children with recurrent LRTIs that limits unnecessary, expensive and time-consuming investigations. The children can be divided into three groups on the basis of their personal and family history and clinical findings: 1) otherwise healthy children who do not need further investigations; 2) those with risk factors for respiratory infections for whom a wait-and-see approach can be recommended; and 3) those in whom further investigations are mandatory. However, regardless of the origin of the recurrent LRTIs, it is important to remember that prevention by means of vaccines against respiratory pathogens (i.e. type b Haemophilus influenzae, pertussis, pneumococcal and influenza vaccines) can play a key role.

Safety, tolerability, and efficacy of high-frequency chest wall oscillation in pediatric patients with cerebral palsy and neuromuscular diseases: an exploratory randomized controlled trial

Airway secretions and infections are common in cerebral palsy and neuromuscular diseases. Chest physiotherapy is standard therapy but effort is substantial. High-frequency chest wall oscillation is used in cystic fibrosis but tolerability and safety data in cerebral palsy and neuromuscular disease are limited. A prospective, randomized, controlled trial of high-frequency chest wall oscillation and standard chest physiotherapy was performed in participants with neuromuscular disease or cerebral palsy. Outcome measures included respiratory-related hospitalizations, antibiotic therapy, chest radiographs, and polysomnography. Care-givers were questioned regarding therapy adherence. A total of 28 participants enrolled, 23 completed (12 chest physiotherapy, mean study period 5 months). No adverse outcomes were reported. Adherence to prescribed regimen was higher with high-frequency chest wall oscillation (P = .036). Our data suggest safety, tolerability, and better compliance with high-frequency chest wall oscillation. Improvement in airway clearance may help prevent hospitalizations. Larger controlled trials are required to confirm these results.

Novel methods of ambulatory physiologic monitoring in patients with neuromuscular disease

This is a summary of the presentation on novel methods of ambulatory physiologic monitoring in patients with neuromuscular disease, presented as part of the program on pulmonary management of pediatric patients with neuromuscular disorders at the 30th annual Carrell-Krusen Neuromuscular Symposium on February 20, 2008.

Airway clearance in Duchenne muscular dystrophy

This is a summary of the presentation on airway clearance in neuromuscular disorders presented as part of the program on airway clearance in Duchenne muscular dystrophy at the 30th annual Carrell-Krusen Neuromuscular Symposium on February 20, 2008.

Early laparoscopic fundoplication and gastrostomy in infants with spinal muscular atrophy type I

BACKGROUND/PURPOSE

Spinal muscular atrophy (SMA) in children leads to progressive muscle weakness, dysphagia, aspiration, and death. We hypothesized that early laparoscopic fundoplication and gastrostomy in infants with SMA type I could be performed safely perhaps leading to fewer aspiration events and improved nutritional status.

METHODS

Children diagnosed with SMA type I from 2002 through 2005 were included (n = 12). All children underwent laparoscopic Nissen fundoplication with gastrostomy shortly after diagnosis. Postoperative respiratory management and discharge criteria were standardized.

RESULTS

All patients were extubated immediately postoperatively. There were no significant complications. Average time to full feeding and inpatient length of stay were 42 +/- 4.9 hours (range, 30-48 hours) and 78 +/- 22.5 hours (range, 44-120 hours), respectively. Mean weight-for-length percentile was doubled at 1 year postoperatively (P = .03). The number of respiratory-related hospitalizations in the cohort decreased by almost 50% in the ensuing 12 months after surgery, although this did not reach statistical significance in this small cohort (P = .34).

CONCLUSIONS

Early laparoscopic fundoplication and gastrostomy is safe and is associated with improved nutritional status. A trend toward fewer significant long-term aspiration-related events was seen after fundoplication. To better assess the long-term benefits of performing an antireflux procedure in these high-risk patients, a larger prospective trial comparing current nutritional support practices is needed.

Noninvasive ventilation in immunocompromised pediatric patients: eight years of experience in a pediatric oncology intensive care unit

OBJECTIVE

The experience of noninvasive positive pressure ventilation (NPPV) in the pediatric setting is limited. The aim of the present study is to retrospectively evaluate the effectiveness of NPPV in pediatric immunocompromised patient admitted in our PICU (Pediatric Intensive Care Unit) for acute respiratory failure.

DESIGN/SETTING

Retrospective cohort study of children admitted to the PICU of Hospital do Cancer between June 1997 and May 2005 requiring ventilatory support.

RESULTS

A total of 239 admissions were included. The first mechanical ventilation (MV) technique used was NPPV in 120 (50.2%) patients [noninvasive ventilation (NIV) group] and conventional MV in 119 (49.8%) [invasive ventilation (IV) group]; 25.8% of the patients from the NIV group subsequently required intubation. Patients in the IV group were more likely to be in a severe clinical status. Characteristics associated with severe clinical status were median value for therapeutic intervention scoring system score (37.5 points IV vs. 29 points NIV, P<0.0001), presence of >2 organs failure (63.6% IV vs. 36.4% NIV, P<0.0001), cardiac failure (62.5% IV vs. 37.5% NIV, P<0.0001), and septic shock (63.9% IV vs. 36.1% NIV, P<0.0001). Documented severe pulmonary disease was significantly higher (67.6%) in IV group, P=0.02. Baseline values of arterial pCO2, hypoxemia, arterial pH, and respiratory rate did not differ between the groups. Multivariate analysis showed that independent predictive factors for intubation were solid tumors (P=0.012), cardiovascular dysfunction (P<0.0001), and therapeutic intervention scoring system score >or=40 points (P=0.018).

CONCLUSIONS

Our results encourage the use of NPPV as a first-line treatment in children with malignancies who develops acute respiratory failure, except in those with severe hemodynamic status.

Use of the laryngeal mask airway in patients with severe muscular dystrophy who require sedation or anesthesia

Severe muscular dystrophy (MD) has historically led to death in early adulthood, due to mainly cardiopulmonary complications. However, with newer methods of cardiac and respiratory management, survival has improved, and patients with MD are more frequently undergoing procedures requiring deep sedation or anesthesia. Respiratory management of these patients during procedures is challenging; safe and effective options for respiratory support are needed. In this report, we describe our experience using the laryngeal mask airway (LMA) to provide respiratory support during deep sedation or anesthesia for eight patients with severe MD during the following medical procedures: eight percutaneous endoscopic gastrostomy (PEG) placements, three lithotripsies, and placement of an implantable cardioverter-defibrillator. We also review the benefits and risks of the LMA in the context of other respiratory support options for people with MD, and the integral role of non-invasive positive pressure ventilation (NPPV) during induction of and recovery from deep sedation or general anesthesia.

Respiratory failure in infants due to spinal muscular atrophy with respiratory distress type 1

BACKGROUND

Spinal muscular atrophy with respiratory distress type 1 (SMARD1) is a rare autosomal recessive neuromuscular disease of unknown prevalence characterized by degeneration of anterior horn alpha-motoneurons and manifesting in the first 6months of life as life-threatening irreversible diaphragmatic paralysis associated with progressive symmetrical muscular weakness (distal lower limbs mainly involved), muscle atrophy, and peripheral sensory neuropathy.

SETTING

Pediatric intensive care unit of tertiary care hospital.

PATIENTS

We present two new cases of SMARD1 and report two new mutations in the gene IGHMBP2 which encodes immunoglobulin mu-binding protein 2 on chromosome 11q13.

CONCLUSIONS

SMARD1 is a poor-prognosis disease that should be considered when acute respiratory insufficiency, of suspected neuromuscular or unclear cause, develops during the first 6months of life. Diaphragmatic paralysis, manifesting as dyspnea and paradoxical respiration, is the most prominent presenting sign and diaphragmatic motility should be investigated early by fluoroscopy or ultrasound. Electromyography and nerve conduction studies revealing peripheral motor and sensory neuropathy then suggest the diagnosis which should be confirmed by genetic analysis.

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

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

Spirometry is affected by intelligence and behavior in Duchenne muscular dystrophy

Children with Duchenne muscular dystrophy (DMD) have progressive respiratory muscle weakness. Spirometry monitors progress, but is effort-dependent. Intelligence quotients (IQ) average one standard deviation below normal, and behavioral disturbance is common. Our aim was to assess if impaired intelligence or behavior influences spirometry in children with DMD, and if computerized visual incentives (CVI) are beneficial. Forty-seven boys with DMD, of mean age 12.6 years (range, 6-19), were recruited. Full-scale, performance, and verbal IQ, and parent-and-teacher-reported oppositional behavior scores, were recorded. Each was divided into moderate, mild, and no impairment groups. A randomized crossover design was applied to performing spirometry with or without CVI first. A Jaeger Masterscope (version 4.60) was used. Linear regression defined the relationship between spirometry and both IQ and behavior scores. The paired Student's t- test compared spirometry performed with and without CVI for the overall group and subgroups. Boys with DMD can adequately perform spirometry. There is an association between %FEV1 and %FVC with full-scale (r = 0.50, P = 0.002; r = 0.49, P = 0.003, respectively), performance (r = 0.68, P < 0.0005; r = 0.68, P < 0.0005, respectively) and verbal (r = 0.39, P = 0.043; r = 0.36, P = 0.037, respectively) IQ, but not with parent (P = 0.77, P = 0.70, respectively) or teacher (P = 0.90, P = 0.90, respectively)-reported oppositional behavior scores. The effect of CVI was significant in those with moderate full-scale (P = 0.03), performance (P = 0.002), and verbal (P = 0.02) intellectual impairment, and moderately severe teacher-reported oppositional behavior (P = 0.02). In conclusion, spirometry results are related to intelligence in DMD. Using CVI improves the FVC obtained in those with moderate intellectual or behavioral impairment.

Relationship between peak cough flow and spirometry in Duchenne muscular dystrophy

Spirometry is used to monitor respiratory progress in children with Duchenne muscular dystrophy (DMD). Mucociliary clearance depends on cough strength, which can be measured by peak cough flow (PCF). It is not routinely measured in most centers. When the PCF falls below 270 l/min, mucociliary clearance is likely to be impaired during viral illnesses, and techniques to assist mucociliary clearance should be taught. There is no known association between spirometry and PCF. Our aim was to assess if PCF relates to spirometry measures, and if spirometry can be used to predict when the PCF <270 l/min. Children with DMD aged 6-19 years were recruited. Spirometry was performed with a Jaeger Masterscope with version 4.60 software. PCF was performed with a Wright peak flow meter. Data were collected into an Access '97 database, and statistics were performed with Stata 7.0. The association between PCF and spirometry was defined with linear regression. Logistic regression was used to predict the probability that the PCF would be <270 l/min for any given forced vital capacity (FVC) or forced expired volume in 1 sec (FEV1). The risk ratios for PCF <270 l/min were calculated for the spirometry parameters. PCF is associated with FVC (R2, 0.72) and FEV1 (R2, 0.69). The likelihood of PCF <270 l/min rises when FVC <2.l and FEV1 <2.l/sec. The risk ratio for PCF <270 l/min when FVC <2.1 l is 4.80 (1.72-13.40) and when FEV1 <2.1 l/sec is 3.94 (1.43-10.85). In children with DMD, PCF should be measured when FVC <2.1 l or FEV1 <2.1 l/sec, so that techniques to assist with mucociliary clearance can be effectively used.

Recognition and management of respiratory dysfunction in children with tetraplegia

Children less than 15 years of age comprise approximately 3% to 5% of all new spinal injuries each year. Approximately one third of these children sustain injuries to the cervical spine. Respiratory complications of spinal cord injuries at the level of C5 and above may include diaphragm dysfunction, retained airway secretions, recurrent aspiration, nocturnal hypoventilation, and respiratory failure. Although most newly injured children with cervical injuries above the level of C5 will require mechanical ventilation acutely, many eventually will be able to be weaned from technology. Despite their ability to breathe without mechanical support, these children often develop ongoing issues associated with respiratory compromise, which interfere with daily activities and can negatively affect quality of life. Poor endurance, failure to thrive, recurrent pneumonia, and sleep-disordered breathing all may be indications of significant respiratory dysfunction. This article describes assessment tools and management strategies aimed at supporting optimal health and preventing recurrent complications associated with unrecognized or untreated respiratory dysfunction.