Home-Based Mechanical Ventilation and Neuromuscular Disease
Improving access to sleep medicine care for patients with NMD
Sleep-disordered breathing (SDB) occurs in up to 5% of children, with adverse implications for growth and development. Children with neuromuscular disease are at significantly higher risk than unaffected children (Chiang et al. Children. 2018;5:e78). Respiratory dysfunction that may present as SDB before daytime impairment in gas exchange is evident. Diagnosing and treating SDB (to include OSA, CSA, and hypoventilation syndromes) early can significantly improve morbidity and mortality.
Dr. Jacob Collen
Unfortunately, diagnostic sleep medicine resources are limited. Children may wait up to a year or more for definitive testing with in-laboratory, attended polysomnography (PSG). Among children with neuromuscular disease, fewer than 10% may undergo a sleep clinic evaluation, and, of those that do, they may have only one visit over a 3-year period of care (Rose et al. Pediatr Pulmonol. 2018 Oct;53:1378). Home sleep testing (HST) has been evaluated as an alternative to PSG given lower cost, availability, and advantage of the child sleeping in his/her own bed. Although HST is indicated in adults with a high pretest probability for moderate to severe OSA, it is not indicated in children, given the potential to underestimate disease severity or to miss the diagnosis entirely (Kirk et al. J Clin Sleep Med. 2017 Oct 15;13[10]:1199). HST lacks electroencephalogram (EEG) and capnography. Technical recording mishaps are more common in children, but in-lab PSG has the advantage of on-site troubleshooting by a technologist. A recently published study by Fishman and colleagues attempted to compare gold standard in-lab PSG to HST with capnography (Fishman et al. J Clin Sleep Med. 2018 Dec 15;14[12]:2013). Despite a well-designed study with a carefully selected population, HST failed to reliably diagnose SDB. HST underestimated disease severity and, in some cases, missed the diagnosis of SDB entirely. The addition of end tidal CO2 monitoring failed to improve diagnostic accuracy, and HST and PSG-ETco2 values were poorly correlated.
Although children with neuromuscular disease face long wait times for sleep evaluations, HST is clearly not the solution for now. It remains to be seen if innovations in HST with extended monitoring (and transcutaneous CO2) become viable. In the meantime, finding ways to improve access to sleep medicine care for children with neuromuscular disease is a must.
Jacob Collen, MD, FCCP
Steering Committee Member
Interstitial and Diffuse Lung Disease
Idiopathic pneumonias that are not all that idiopathic
Despite being defined as an individual entity for research purposes in 2015 (Fisher et al. Eur Respir J. 2015;46:976), interstitial pneumonias with autoimmune features (IPAF) remain a heterogeneous group of interstitial lung diseases that puzzle the clinician. Since the introduction of the IPAF definition, there have been attempts to validate the diagnostic criteria and study their prognostic implications. Some of these studies showed differential prognosis in patients who met the IPAF criteria (Oldham et al. Eur Respir J. 2016;47:1767).
Although the implications of the presence of autoimmune antibodies in idiopathic interstitial pneumonias (IIPs) is not fully understood, the treatment often entails immunosuppression, especially in those with non-UIP patterns of disease and/or clinical features of autoimmune disease. The stakes are high when IIPs are associated with antibodies correlated with rapidly progressive disease, such as MDA-5 antibody or antisynthetase antibodies. Pulmonologists often lack the clinical expertise to detect occult autoimmune disorders, though the role of the rheumatologist in facilitating the diagnosis and treatment of IPAF is not well delineated. Most health-care systems are not equipped with collaborative ILD-rheumatology clinics or even easy access to a rheumatologist. There is a need for real-world pragmatic studies to establish the optimal way to evaluate patients with ILD for autoimmune features and identify patients who would benefit most from an early referral to rheumatology to aid with diagnosis, treatment, and sometimes monitoring for extrapulmonary manifestations of autoimmune disorders.
Avanthika Thanushi Wynn, MD
Steering Committee Fellow-in-Training