Respiratory Function and Sleep Disordered Breathing in Pediatric Duchenne Muscular Dystrophy

The impact of sleep in high-risk infants

Most of an infant's day is devoted to sleep - and normal sleep is vital to normal brain development. Sleep disruptions may impair overall health, well-being, and neurodevelopment. Disruptors of sleep and circadian health, such as noise, light, respiratory support, and clinical interventions, are highly prevalent in hospital and nursing care facilities. These factors particularly affect infants who already have an increased risk of sleep disorders and their consequences due to an underlying disease. Preterm infants and infants with disorders such as neonatal abstinence syndrome, craniofacial malformations, congenital heart disease, hypoxic-ischemic encephalopathy, Chiari-malformation/myelomeningocele, congenital musculoskeletal disease, and Down syndrome are all at high risk for impaired development of sleep-wake cycling and for sleep-disordered breathing. Since abnormal sleep is a potentially treatable risk factor for impaired neurodevelopment, there is an urgent need for effective monitoring, timely interventions, and treatment strategies to improve sleep physiology and thereby optimize overall neurodevelopment in these high-risk populations. IMPACT: Healthy sleep plays a fundamental role in normal infant brain development. Many factors can disrupt sleep during a hospital stay. This is particularly important for infants who have an increased risk of sleep disorders due to neonatal disorders such as prematurity, congenital heart disease, or Chiari malformation. Sleep protective strategies are readily available and need to be systematically implemented into hospital care.

A New Perspective on Drugs for Duchenne Muscular Dystrophy: Proposals for Better Respiratory Outcomes and Improved Regulatory Pathways

New drugs for Duchenne muscular dystrophy (DMD) are emerging rapidly. However, we and others believe these drugs are achieving regulatory approval prematurely. It is the cardiorespiratory complications of DMD that cause the disease's major morbidities and that determine survival. Thus, to be truly effective, a new drug must improve cardiorespiratory function; instead, new drugs are approved for patient use via accelerated regulatory pathways that rely on surrogate outcome measures with unproven clinical benefits (such as tissue levels of non-biologic, truncated dystrophin) and on scales that reflect muscle strength (such as small improvements in timed activities). In DMD, cardiorespiratory complications occur in "older" individuals who are in the non-ambulatory stage of the disease. In contrast, accelerated approvals are based on data from young, ambulatory subjects, a group that essentially never experiences cardiorespiratory complications. When drug studies do obtain cardiorespiratory data, their methodologies are suboptimal. We critically review these methodologies in detail, including problems with the use of threshold levels of respiratory function as outcome measures; problems with the use of historical controls, whose results vary widely, and are influenced by uncontrolled variables related to their observational nature; and the limitations of using percent predicted forced vital capacity (FVC %pred), and its single rate of decline across a wide range of age and function, as a preferred respiratory outcome measure. We discuss the advantages of an alternative respiratory outcome, the absolute value of FVC with aging (the "Rideau plot"). Unlike FVC %pred, the Rideau plot considers distinct phenotypes rather than aggregating all individuals into a single respiratory trajectory. Key features of the Rideau plot can show the nature and timing of a drug's effect on respiratory function, making it a potentially better outcome measure for assessing the respiratory effects of a drug. With this article, we use our respiratory perspective to critically examine the DMD drug development process and to propose improvements in study methodologies and in the regulatory processes that approve new drugs.

Can Sniff Nasal Inspiratory Pressure be a guide in detecting of sleep-disordered breathing in children with Duchenne Muscular Dystrophy?

PURPOSE

Duchenne muscular dystrophy (DMD) is a severe, progressive condition characterized by muscle degeneration and weakness, significantly affecting respiratory function. This study aimed to evaluate the presence of sleep-disordered breathing (SDB) in children with DMD and investigate the relationships between sleep and respiratory function using spirometry, sniff nasal inspiratory pressure (SNIP), and polysomnography (PSG) along with capnography.

RESEARCH QUESTION

Can low SNIP be a guide for detecting respiratory muscle involvement early and determining the right time to perform early PSG and capnography in DMD?

STUDY DESIGN

Prospective, observational, cross-sectional study.

METHODS

This study included DMD patients aged <18 years. Pulmonary function tests were conducted using spirometry and SNIP, and maximum inspiratory and expiratory pressure were measured. PSG and capnography were performed within two weeks after the pulmonary function tests, and their relationships with each other were investigated.

RESULTS

The study included 44 children. Obstructive sleep apnea syndrome (OSAS) was present in 70.5 % of patients, while nocturnal hypoventilation was observed in 4.5 %. SNIP values were significantly lower in patients with moderate-to-severe OSAS than in those without OSAS. An SNIP value below 40 cm H2O was associated with a 92.8 % prevalence of OSAS.

CONCLUSION

SNIP is a valuable, noninvasive marker for the early detection of respiratory muscle involvement and SDB in patients with DMD. This study highlights the need for early and regular respiratory monitoring in children with DMD to enhance care and quality of life.

Definition of diaphragmatic sleep disordered breathing and clinical meaning in Duchenne muscular dystrophy

BACKGROUND

Diaphragmatic sleep disordered breathing (dSDB) has been recently identified as sleep dysfunction secondary to diaphragmatic weakness in Duchenne muscular dystrophy (DMD). However, scoring criteria for the identification of dSDB are missing.This study aimed to define and validate dSDB scoring criteria and to evaluate whether dSDB severity correlates with respiratory progression in DMD.

METHODS

Scoring criteria for diaphragmatic apnoea (dA) and hypopnoeas (dH) have been defined by the authors considering the pattern observed on cardiorespiratory polygraphy (CR) and the dSDB pathophysiology.10 sleep professionals (physiologists, consultants) blinded to each other were involved in a two-round Delphi survey to rate each item of the proposed dSDB criteria (Likert scale 1-5) and to recognise dSDB among other SDB. The scorers' accuracy was tested against the authors' panel.Finally, CR previously conducted in DMD in clinical setting were rescored and diaphragmatic Apnoea-Hypopnoea Index (dAHI) was derived. Pulmonary function (forced vital capacity per cent of predicted, FVC%pred), overnight oxygen saturation (SpO2) and transcutaneous carbon dioxide (tcCO2) were correlated with dAHI.

RESULTS

After the second round of Delphi, raters deemed each item of dA and dH criteria as relevant as 4 or 5. The agreement with the panel in recognising dSDB was 81%, kappa 0.71, sensitivity 77% and specificity 85%.32 CRs from DMD patients were reviewed. dSDB was previously scored as obstructive. The dAHI negatively correlated with FVC%pred (r=-0.4; p<0.05). The total number of dA correlated with mean overnight tcCO2 (r 0.4; p<0.05).

CONCLUSIONS

dSDB is a newly defined sleep disorder that correlates with DMD progression. A prospective study to evaluate dSDB as a respiratory measure for DMD in clinical and research settings is planned.

Pediatric pulmonology year in review 2022: Sleep medicine

Pediatric pulmonology publishes original research, review articles, and case reports on a wide variety of pediatric respiratory disorders. In this article, we summarized the past year's publications in sleep medicine and reviewed selected literature from other journals in this field. We focused on original research articles exploring aspects of sleep-disordered breathing in patients with underlying conditions such as asthma, neuromuscular disorders, and Down syndrome. We also explored sleep-disordered breathing risk factors, monitoring, diagnosis, and treatment; and included recent recommendations for drug-induced sleep endoscopy and ways to monitor and improve PAP adherence remotely.

Pediatric Sleep Respiratory Disorders: A Narrative Review of Epidemiology and Risk Factors

Sleep is a fundamental biological necessity, the lack of which has severe repercussions on the mental and physical well-being in individuals of all ages. The phrase "sleep-disordered breathing (SDB)" indicates a wide array of conditions characterized by snoring and/or respiratory distress due to increased upper airway resistance and pharyngeal collapsibility; these range from primary snoring to obstructive sleep apnea (OSA) and occur in all age groups. In the general pediatric population, the prevalence of OSA varies between 2% and 5%, but in some particular clinical conditions, it can be much higher. While adenotonsillar hypertrophy ("classic phenotype") is the main cause of OSA in preschool age (3-5 years), obesity ("adult phenotype") is the most common cause in adolescence. There is also a "congenital-structural" phenotype that is characterized by a high prevalence of OSA, appearing from the earliest ages of life, supported by morpho-structural abnormalities or craniofacial changes and associated with genetic syndromes such as Pierre Robin syndrome, Prader-Willi, achondroplasia, and Down syndrome. Neuromuscular disorders and lysosomal storage disorders are also frequently accompanied by a high prevalence of OSA in all life ages. Early recognition and proper treatment are crucial to avoid major neuro-cognitive, cardiovascular, and metabolic morbidities.

Sleep apnoea and hypoventilation in patients with five major types of muscular dystrophy

BACKGROUND

The characteristics of and relationship between sleep apnoea and hypoventilation in patients with muscular dystrophy (MD) remain to be fully understood.

METHODS

We analysed 104 in-laboratory sleep studies of 73 patients with MD with five common types (DMD-Duchenne, Becker MD, CMD-congenital, LGMD-limb-girdle and DM-myotonic dystrophy). We used generalised estimating equations to examine differences among these types for outcomes.

RESULTS

Patients in all five types had high risk of sleep apnoea with 53 of the 73 patients (73%) meeting the diagnostic criteria in at least one study. Patients with DM had higher risk of sleep apnoea compared with patients with LGMD (OR=5.15, 95% CI 1.47 to 18.0; p=0.003). Forty-three per cent of patients had hypoventilation with observed prevalence higher in CMD (67%), DMD (48%) and DM (44%). Hypoventilation and sleep apnoea were associated in those patients (unadjusted OR=2.75, 95% CI 1.15 to 6.60; p=0.03), but the association weakened after adjustment (OR=2.32, 95% CI 0.92 to 5.81; p=0.08). In-sleep average heart rate was about 10 beats/min higher in patients with CMD and DMD compared with patients with DM (p=0.0006 and p=0.02, respectively, adjusted for multiple testing).

CONCLUSION

Sleep-disordered breathing is common in patients with MD but each type has its unique features. Hypoventilation was only weakly associated with sleep apnoea; thus, high clinical suspicion is needed for diagnosing hypoventilation. Identifying the window when respiratory muscle weakness begins to cause hypoventilation is important for patients with MD; it enables early intervention with non-invasive ventilation-a therapy that should both lengthen the expected life of these patients and improve its quality.Cite Now.

Evaluation and diagnosis of pediatric obstructive sleep apnea—An update

Purpose

Formal overnight polysomnography (PSG) is required to diagnose obstructive sleep apnea (OSA) in children with sleep disordered breathing (SDB). Most clinical guidelines do not recommend home-based tests for pediatric OSA. However, PSG is limited by feasibility, cost, availability, patient discomfort, and resource utilization. Additionally, the role of PSG in evaluating disease impact may need to be revised. There is a strong need for alternative testing that can stratify the need for PSG and improve the time to diagnosis of OSA. This narrative review aims to evaluate and discuss innovative approaches to pediatric SDB diagnosis.

Findings

Methods to evaluate pediatric SDB outside of PSG include validated questionnaires, single-channel recordings, incorporation of telehealth, home sleep apnea testing (HSAT), and predictive biomarkers. Despite the promise, no individual metric has been found suitable to replace standard PSG. In addition, their use in combination to diagnose OSA diagnosis still needs to be defined.

Summary

When combined with adjunct assessments, HSAT advancements may accurately evaluate SDB in children and thus minimize the need for overnight in-laboratory PSG. Further studies are required to confirm diagnostic validity vis-à-vis PSG as a reference standard.

Respiratory Insufficiency in Neuromuscular Disease (RIND): A Delphi Study to Establish Consensus Criteria to Define and Diagnose Hypoventilation in Pediatric Neuromuscular Disease

Chronic respiratory failure is a common endpoint in the loss of respiratory muscle function in patients with progressive neuromuscular disease (NMD). Identifying the onset of hypoventilation is critical to allow for the timely introduction of ventilator support and effectively manage respiratory failure [1-3]. While there are accepted criteria governing the diagnosis of hypoventilation during polysomnography (PSG) [4], there is concern that criteria are insufficient for identifying hypoventilation in the earlier stages of respiratory insufficiency related to NMD. The purpose of this project was to identify more sensitive criteria for identifying hypoventilation.

METHODS

Fifteen pediatric pulmonologists with broad experience in managing patients with NMD, 10 of whom were board certified in and practice sleep medicine, were assembled and performed a review of the pertinent literature and a two-round Delphi process with 6 domains (Table 1).

RESULTS

Within the 6 domains there were three pertinent items per domain (Table 2). There was clear agreement on findings on history (morning headaches) and pulmonary function testing (FVC < 50% or awake TcCO2 > 45 mmHg) indicating a high concern for nocturnal hypoventilation. There was close agreement on the definitions for nocturnal hypercapnia and hypoxemia. PSG criteria were identified that indicate a patient is likely in the transitional phase from adequate ventilation to hypoventilation.

DISCUSSION

We identified a set of clinical criteria that may allow for more sensitive diagnosis of hypoventilation in NMD and earlier initiation of non-invasive ventilation leading to a reduction in the respiratory morbidity in progressive NMD. These criteria need to be further and more broadly validated prospectively to confirm their utility.