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Highlights of CHEST 2018 – Sleep Disorders
Highlights of CHEST 2018 – Sleep Disorders
Katrina Mountfort, Senior Medical Writer, Touch Medical Media, UK
Insights into sleep disorder research presented at the 84th annual meeting for the American College of Chest Physicians (CHEST), San Antonio, TX, US, October 6-10, 2018.

Obstructive sleep apnea (OSA) was once considered a very rare disorder but recent epidemiological studies show an astonishingly high prevalence. Moderate-to-severe OSA has been found in up to 50% of men and up to 31% of women in the middle-aged population (as defined by an apnea–hypopnea index ≥15).1–3 It is characterized by breathing cessation and impaired oxygenation during sleep, resulting in sleep fragmentation and impaired daytime activities, and is associated with cardio-metabolic diseases and mortality.4 When the large number of individuals with this disorder is multiplied by the cost of adverse effects that can be attributed to OSA, the total disease burden is huge. CHEST 2018, the 84th annual meeting for the American College of Chest Physicians, was held Oct 6–10, 2018, in San Antonio, Texas, and features a number of presentations on OSA, highlights of which are discussed in this article.

The high prevalence of OSA means that sleep clinics are struggling to meet demands. Continuous positive airway pressure (CPAP) therapy is commonly prescribed for patients with OSA. A CPAP machine delivers a constant flow of airway pressure to the throat to ensure that the airway remains open during sleep, effectively treating the spontaneous pauses in breath associated with OSA. If patients are compliant with CPAP therapy, it should be possible to monitor them through CPAP downloads by a registered sleep technologist-educator with supervision from an advanced practice clinician. This hypothesis was investigated in a study presented at CHEST. Compliance was defined as usage of CPAP >80% nights for >5hrs of average use per night for 6 months or more; patient agreement to undergoing follow-up in a “stable CPAP clinic”, absence of other sleep co-morbidities such as insomnia, untreated restless legs syndrome, rapid eye movement sleep behavior disorder, or other conditions considered to complicate CPAP usage. Patients who met these criteria were followed by a sleep coordinator who tracked downloads every 6 months, and were also seen once yearly by an advanced practice clinician. Among 837 patients from three sites, 335 were scheduled for 20-minute follow-up visits by the advanced practice clinician. Ten patients did not make these appointments and were contacted for subsequent follow-ups by the coordinator. Seven were transferred back to the referring healthcare provider for CPAP non-compliance or for additional sleep problems requiring further treatment. The clinic saved 110 hours of physician time in terms of return patient visits. Additionally, this clinic achieved long term management of stable OSA patients without the need for primary care providers while maintaining high rates of CPAP adherence.5 This study has important clinical implications and the use of “stable CPAP clinics” should become widespread.

The reduction in oropharyngeal muscle tone in the upper airway is an important factor in snoring and OSA. Neuromuscular electrical stimulation (NEMS) is the application of an electric current to muscles to induce contractions, and is routinely used for increasing muscle tone, strength, and functional performance in rehabilitation and regenerative medicine. A small study presented at CHEST used a novel daytime intra-oral NEMS device for the tongue to treat snoring and mild OSA in 27 patients. The use of the SnooZeal® (SnooZeal, Leicester, UK) intra-oral NEMS device was associated with significant improvement in snoring and sleep quality.6 This intervention therefore warrants further study.

Surgical patients with OSA are at increased risk for perioperative complications. Postoperative supplemental oxygen is commonly used to treat these patients. Despite this, some patients remain at risk of postoperative oxygen desaturation, which is associated with increased ICU admissions and adverse cardiopulmonary events. Nasal high flow (NHF) therapy is a promising novel oxygen delivery device that offers some beneficial effects over conventional oxygen systems. A high flow of heated and humidified gas mixture is administered, promoting higher and more stable inspiratory oxygen fraction values, decreasing dead space and generating a positive airway pressure that can reduce the work of breathing and enhance patient comfort and tolerance.7 A single-blinded trial recruited 50 patients with moderate-to-severe OSA who were not compliant with CPAP machine use to receive NHF at low flow (30 LPM) plus oxygen at 1 LPM or oxygen supplement at 1 LPM via nasal cannula (control) during the first post-surgical night. The use of NHF at low flow was not found to confer any advantages over supplemental oxygen alone; higher flow may be needed.8 Further studies are warranted to determine the role of NHF in the perioperative management of OSA patients.

OSA associated with obesity is highly prevalent in children and adolescents.9 A small study presented at CHEST yielded potential new insights into this association. A retrospective analysis was performed of 81 pediatric patients with obesity (body mass index ≥95th percentile) who underwent evaluation with polysomnography and echocardiography. Despite similar degrees of obesity and systolic blood pressure (BP), pediatric patients with OSA had significantly higher diastolic BP, heart rate, and abnormal metabolic profile including elevated alanine transaminase, aspartate transaminase, triglycerides, and glycated hemoglobin (HbA1c). While larger studies are required to confirm this finding, these data suggest that abnormal metabolic profile rather than weight is associated with increased severity of OSA in obese children. Screening this patient population may help identify those at risk for more significant OSA.10

The treatment of OSA involves a number of disciplines, but current care delivery is often fragmented, with different disciplines acting in isolation. A Chinese prospective randomized controlled study compared a new integrated model of care for OSA with routine practice. At 1 month follow-up, the integrated multidisciplinary OSA model achieved better sleep Functional Outcome Sleep Questionnaire (FOSQ) scores (-1.5±5.1 versus -0.60±4.7, p=0.01) and shorter clinic appointment waiting time than routine care (13.1 versus 27.3 days, p=0.03) among patients with OSA.11 While longer follow-up is needed to draw firm conclusions, this study has demonstrated the need for new model of care delivery in the outpatient clinic setting for OSA.

These diverse presentations have highlighted the breadth of research that is being conducted in OSA, and should lead to improvements in the management of this disorder.

References

1. Heinzer R, Vat S, Marques-Vidal P, et al. Prevalence of sleep-disordered breathing in the general population: the HypnoLaus study. Lancet Respir Med. 2015;3:310–8.
2. Franklin KA, Sahlin C, Stenlund H, et al. Sleep apnoea is a common occurrence in females. Eur Respir J. 2013;41:610–5.
3. Arnardottir ES, Bjornsdottir E, Olafsdottir KA, et al. Obstructive sleep apnoea in the general population: highly prevalent but minimal symptoms. Eur Respir J. 2016;47:194–202.
4. Young T, Peppard PE, Gottlieb DJ. Epidemiology of obstructive sleep apnea: a population health perspective. Am J Respir Crit Care Med. 2002;165:1217–39.
5. Sundar K, Ryujin D, Willis A, et al. Creation of “stable CPAP clinic” for population management of PAP-adherent sleep apnea patients through sleep co-ordinators. Presented at the CHEST Annual Meeting 2018; October 6–10, 2018; San Antonio, TX.
6. Sama A, Wessolleck E, Stuck B, et al. Daytime intra-oral neuromuscular stimulation with SnooZeal for the treatment of snoring and mild sleep apnea. CHEST. 154 Suppl:1081A.
7. Ischaki E, Pantazopoulos I, Zakynthinos S. Nasal high flow therapy: a novel treatment rather than a more expensive oxygen device. Eur Respir Rev. 2017;26: pii: 170028. DOI: 10.1183/16000617.0028-2017.
8. Selim B, Gali B, Kashyap R, et al. Nasal high flow therapy versus oxygen supplementation in postoperative care of obstructive sleep apnea patients with CPAP non-compliance: a pilot randomized study. CHEST. 154 Suppl: 1133A.
9. Narang I, Mathew J. Childhood obesity and obstructive sleep apnea. J Nutr Metab. 2012;2012:134202.
10. Mathur K, Barraza G, Khan M, et al. Cardiometabolic risk factors in obese children with OSA. CHEST. 154 Suppl:817A–18A.
11. Chua A-P, Guo W, Han T-O, et al. Short-term impact of an integrated multidisciplinary patient-centered coordinated care treatment in OSA. CHEST. 154 Suppl:1087A–88A.