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Improving Compliance With Continuous Positive Airway Pressure Machines In Patients With Sleep Apnea

Wendy S. Sprague, DVM, PhD

Sprague Medical and Scientific Communications


Obstructive or central sleep apneas are disorders associated with interrupted sleep that can lead to several chronic disorders and diseases. The causes of obstructive sleep apnea are multifactorial, but there is a strong association between obesity and obstructive sleep apnea. Medical disorders or diseases associated with obstructive sleep apnea are hypertension, heart failure, cardiac arrhythmias, type 2 diabetes, chronic obstructive pulmonary disease, and neurologic impairment. Continuous positive airway pressure (CPAP) devices are considered the most effective treatment for obstructive sleep apnea; however, compliance with use is a common problem among patients. It is, therefore, important to educate patients into the reasons why using a CPAP device is in their best interest. Patient complaints regarding CPAP use are mostly associated with the masks and include poor sleep, less intimacy, facial irritation, claustrophobia, and expense. And, approximately 50% of CPAP users have nasal congestion, dry mouth, and skin irritation. Methods to remedy some of these complaints are to decrease mask and strap tension, to have different mask types and sizes available, and to use pads and lotions. Protecta-Gel, a unique protective mask barrier made from a mineral-based elastomer gel, has an innovative design with a novel patented “rib-like” design that is solely responsible for its added protection. And, not only is it hypoallergenic and safe for use on sensitive skin, the design allows for greater cushioning in areas most afflicted by CPAP use.

With the myriad of diseases and disorders associated with sleep apnea, and with the ever-increasing number of sleep apnea cases diagnosed, strategies to encourage optimal CPAP use are of paramount importance.

Improving Compliance With Continuous Positive Airway Pressure Machines In Patients With Sleep ApneaSleep apnea is a sleep disorder that results in fragmented breathing due to upper airway collapse. Two types of sleep apnea exist, obstructive sleep apnea (OSA) and central sleep apnea (CSA). Obstructive spleen apnea is the most common form and is strongly associated with obesity. However, the real cause of OSA is multifactorial, involving upper airway conformation, neck thickness, weakened muscles involved in the movement of air through the throat, and lower lung volume during sleep (Floras, 2015; Giles et al., 2006). As many as 15 million Americans have this disorder, and estimates indicate that many more people remain undiagnosed (Lee, Nagubadi, Kryger, & Mokhlesi, 2008). OSA is more common in males than in females and symptoms are quite varied with some individuals having no symptoms at all. Additional risk factors associated with OSA include type 2 diabetes, polycystic ovarian disease, hypertension refractory to drug treatment, coronary artery disease, congestive heart failure, and stroke (Lee et al., 2008). Central sleep apnea (CSA) is much less common, and found in < 1% of the general population, but is as many as 37% of patients with heart failure have this disorder (Lyons & Bradley, 2015).

Snoring and associated gasps for air are often the first OSA signs reported by the patient or given by the patient’s spouse or partner. Other symptoms include daytime drowsiness, increased blood pressure, morning headaches and sexual dysfunction (Giles et al., 2006; Somers et al., 2008).

Several OSA screening tests are available, such as questionnaires, and in-home oxygen sleep measurements. However, OSA is most definitively diagnosed in a sleep laboratory where respiration measurements including flow rate, breathing effort, and blood oxygen levels are recorded. Heart rate and rhythm, brain activity, muscle activity, eye movement, and snoring are also observed (Somers et al., 2008). The apnea-hypopnea index (AHI) is a measurement used to determine the severity of sleep apnea with an AHI ranging from < 5 in the case of no sleep apnea to > 30 in the case of severe sleep apnea (Lyons & Bradley, 2015).

Treatment options are multi-factorial, and in the case of obesity, weight loss can result in improved oxygen intake and decreased snoring (Haines et al., 2007; Somers et al., 2008). The continuous positive airway pressure (CPAP) device is considered the treatment of choice for patients with OSA as a marked improvement in blood pressure, daytime drowsiness, and mood was found when the CPAP was used for at least 4 hours per night (Bollig, 2010; Kribbs et al., 1993).

Why are compliance and treatment important?

It is important to encourage patients with sleep apnea to comply with CPAP treatments as several medical disorders are linked to sleep apnea, and consistent use of the CPAP has improved many of these conditions.


The link between OSA and systemic hypertension is controversial, yet half of patients with OSA are hypertensive, and as many as 30% of hypertensive patients have undiagnosed OSA. In addition, 80% of patients with hypertension, which do not respond to antihypertensive drugs, will end up being diagnosed with OSA (Cano-Pumarega et al., 2011; Floras, 2015; Somers et al., 2008). Many studies and meta–analyses (statistical analyses of combined studies on the same topic) on CPAP therapy to correct hypertension have been performed with mixed results. Small improvements in blood pressure were seen in patients with uncontrolled hypertension, severe OSA, and daytime sleepiness. Also, lower blood pressure was seen in sleep apnea patients with good CPAP compliance compared to those with poor CPAP compliance. However, the true effect of CPAP therapy may be missed in many of these studies since most studies were of short duration (3 months or less). (Bakker et al., 2014; Duran-Cantolla et al., 2010; Liu, Cao, Guo, & Dai, 2016; Montesi, Edwards, Malhotra, & Bakker, 2012; Muxfeldt et al., 2015). Longer-term studies are needed to assess the full effect of CPAP compliance in the treatment of resistant hypertension. A long-term study that examined the efficacy of CPAP therapy on the 5-year survival of stroke patients with OSA showed 100% cardiovascular survival in patients that received conventional stroke treatment plus CPAP therapy compared to 89.9% survival in patients who only received conventional stroke treatment (Parra et al., 2015).

Heart Failure

Middle-aged to older Men with OSA are more likely to develop heart failure (HF) than those without OSA. Since both OSA and CSA are frequently associated with HF, some researchers believe that periodic lapses in oxygen intake make it harder for the heart to pump blood. However, to date, no strong evidence connects CPAP treatment with improvement in cardiac illness or death resulting from cardiac disease (Lyons & Bradley, 2015; McEvoy et al., 2016). However, further randomized control trials are being developed to answer these questions (Heeley et al., 2016).

Cardiac Arrhythmias

As many as six million people in the United States have atrial fibrillation (AF), a number that is expected to grow as people live longer. Even more troubling is the fact that AF wholly or partially causes at least 130,000 deaths per year, and this number is increasing (CDC, 2015). Two studies showed that AF is two to four times more likely to occur in patients with sleep apnea than in those without sleep apnea and that patients with more severe sleep apnea were more likely to develop AF (Mehra et al., 2006; Selim et al., 2016). Recent evidence shows that CPAP therapy improves atrial electrical conduction after six months of treatment and several other studies show similar CPAP benefits in the correction of conduction abnormalities (Bayir et al., 2014; Neilan et al., 2013; Russo et al., 2016). Fein et al. reported another significant study in patients with both AF and OSA who underwent pulmonary vein isolation (PVI; an ablative method to correct AF). In this study, patients who used CPAP therapy post-PVI treatment had many fewer AF recurrences compared to patients who did not use a CPAP. And, not only did CPAP compliant patients have fewer arrhythmia recurrences, but antiarrhythmic drugs and further ablations were not needed in these patients compared to patients not using the CPAP (Fein et al., 2013).

Type 2 diabetes

Although the connection with type 2 diabetes and OSA has been conflicting, recent meta-analyses have indicated that moderate to severe OSA may predispose people to develop type 2 diabetes. Moreover, CPAP therapy appears to reduce fasting insulin levels in pre-diabetic patients when compared to similar patients not receiving CPAP therapy. These studies suggest that CPAP therapy could lower the risk of developing type 2 diabetes by decreasing insulin resistance, improving glucose regulation and improving fat breakdown (Chakhtoura & Azar, 2012; Chen et al., 2016; Wang, Bi, Zhang, & Pan, 2013).

Chronic obstructive pulmonary disease (COPD)

Almost 10% of patients with OSA have concurrent COPD (called overlap syndrome), which represents approximately 1% of the general population. These patients, as well as COPD patients without OSA, have a decreased ability to exercise or even walk. The use of CPAP for two nights significantly increased mobility and reduced the resting heart rate in patients with overlap syndrome, and even mild effects were seen in COPD patients without OSA (Chaouat et al., 1995; T. Y. Wang et al., 2013). A recent retrospective study also showed fewer hospitalizations in COPD patients after CPAP therapy compared to before CPAP therapy (Vasquez et al., 2017).

Neurological impairment

Estimates show that OSA is present in about three-fourths of patients with dementia. Scientists hypothesize that OSA may exacerbate cognitive dysfunction in these patients, and this exacerbation could be reversed using CPAP treatment (Ancoli-Israel et al., 2008). This idea is supported by the fact that patients who do not have dementia but have severe OSA had improvements in daytime drowsiness and in memory and learning tasks in as little as 15 days after commencing CPAP treatment (Ferini-Strambi et al., 2003). Another study followed 298 elderly women without dementia for 4.7 years. Mild cognitive impairment or dementia was diagnosed more often in the women with moderate OSA (AHI >15 at baseline) compared to women who did not have OSA, suggesting that CPAP therapy can delay development of cognitive deficits or dementia (Yaffe et al., 2011). And, patients with mild to moderate Alzheimer’s disease and severe OSA that used CPAP therapy to treat OSA had significantly less cognitive decline over a 3-year period compared to patients who did not use CPAP therapy (Troussiere et al., 2014).

Structural brain changes have also been identified people with OSA. In two studies, OSA patients had decreased gray matter volume that was linked to cognitive deficits. However, after 3-6 months of CPAP therapy, gray matter volume increased with a return of executive functioning skills and short-term memory abilities (Canessa et al., 2011; O’Donoghue et al., 2012). Another study of OSA patients showed deficits in brain white matter, which almost entirely reversed after 12 months of CPAP therapy. Memory, attention, and executive function corresponded with the increases in white matter (Castronovo et al., 2014).

Patient complaints using the CPAP

Complaints from patients using CPAP for one month are listed in the graph below (Figure 1). As one can see, machine inconvenience and stuffy nose were the chief complaints. Complaints about poor sleep, less intimacy, facial irritation, claustrophobia, and expense were similar in number (Kribbs et al., 1993). And, almost 50% of CPAP users complained of nasal congestion, dry mouth and skin irritation in another study (Bollig, 2010).

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Figure 1: This graph was derived from “Objective measurement of patterns of nasal CPAP use by patients with obstructive sleep apnea.” Am Rev Respir Dis, 147(4), 887-895. (Kribbs et al., 1993)

For the past twenty years, the goal for optimal CPAP treatment was set at ≥ four hours per night and five days per week, however, only about 34% of CPAP users meet this goal, indicating that compliance is poor. And, this low-level CPAP adherence has not improved even with the development of quieter pumps, softer masks, and more easily carried machines, thus revealing that a significant number of patients do not use the CPAP adequately or stop using it altogether (Rotenberg, Murariu, & Pang, 2016).

Through meta-analysis, it was found that behavioral interventions using motivational training sessions to convince patients of the value that can be gained using the CPAP machine yielded the best improvement in CPAP adherence. These interventions could be individual visits, personal written responses, and web-based programs. Educational interventions using instructional videos with detailed information about CPAP machines, possible problems that can occur, and health benefits also showed improvement in CPAP use. However, CPAP adherence is likely the most improved after multimodal intervention, which includes educational and behavioral intervention, and follow-up visits with doctors, nurses, and respiratory therapists (Bollig, 2010; Wozniak, Lasserson, & Smith, 2014). Another factor that leads to better adherence includes making masks more comfortable. One study showed that better adherence with nasal masks vs. oronasal masks; however, oronasal masks provide more effective therapy (Borel et al., 2013). Moreover, oronasal masks are more likely to be uncomfortable, create red marks, have leaks, and produce nose bridge discomfort (Roy, 2016). Several solutions to alleviate these problems are currently available. These include decreasing mask and strap tension, trying different mask types and sizes, and using pads and lotions (Brill, 2014). Protecta-Gel™ is a protective mask barrier made from a mineral-based elastomer gel, which has a unique patented “rib-like” design that bestows the mask with unparalleled shock absorbing power, creating a greater cushioning effect to the nasal bridge and cheekbones, the most problematic areas associated with CPAP use. It is also naturally hypoallergenic and therefore, safe for use on sensitive skin (Figure 2).  In addition to these benefits, Protecta-Gel™ allows users or caregivers to trim the product ensuring a more accurate fit.

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Figure 2: The unique “rib-like” design of Protecta-Gel


CPAP therapy is currently considered the best treatment to alleviate sleep apnea. Evidence that sleep apnea may incite and exacerbate chronic diseases is growing. Moreover, with awareness of sleep apnea among obese individuals, an expanding population of sleep apneic patients is being identified. And, similar to other chronic diseases and disorders, there is a necessity for early diagnosis and treatment of sleep apnea. Therefore, strategies that encourage optimal CPAP use in these patients are of the utmost importance. A combination of intervention strategies has been shown to have the best efficacy for patient compliance. Finally, future studies to examine the effects of CPAP therapy on various disease processes should include patients with optimal CPAP compliance in place.


Ancoli-Israel, S., Palmer, B. W., Cooke, J. R., Corey-Bloom, J., Fiorentino, L., Natarajan, L., . . . Loredo, J. S. (2008). Cognitive effects of treating obstructive sleep apnea in Alzheimer’s disease: a randomized controlled study. J Am Geriatr Soc, 56(11), 2076-2081. doi:10.1111/j.1532-5415.2008.01934.x

Bakker, J. P., Edwards, B. A., Gautam, S. P., Montesi, S. B., Duran-Cantolla, J., Aizpuru, F., . . . Malhotra, A. (2014). Blood pressure improvement with continuous positive airway pressure is independent of obstructive sleep apnea severity. J Clin Sleep Med, 10(4), 365-369. doi:10.5664/jcsm.3604

Bayir, P. T., Demirkan, B., Bayir, O., Duyuler, S., Firat, H., Guray, U., . . . Tatar, E. C. (2014). Impact of continuous positive airway pressure therapy on atrial electromechanical delay and P-wave dispersion in patients with obstructive sleep apnea. Ann Noninvasive Electrocardiol, 19(3), 226-233. doi:10.1111/anec.12106

Bollig, S. M. (2010). Encouraging CPAP adherence: it is everyone’s job. Respir Care, 55(9), 1230-1239.

Borel, J. C., Tamisier, R., Dias-Domingos, S., Sapene, M., Martin, F., Stach, B., . . . Scientific Council of The Sleep Registry of the French Federation of, P. (2013). Type of mask may impact on continuous positive airway pressure adherence in apneic patients. PLoS One, 8(5), e64382. doi:10.1371/journal.pone.0064382

Brill, A. (2014). How to avoid interface problems in acute noninvasive ventilation. Breathe, 10(3), 231-244. doi:10.1183/20734735.003414

Canessa, N., Castronovo, V., Cappa, S. F., Aloia, M. S., Marelli, S., Falini, A., . . . Ferini-Strambi, L. (2011). Obstructive sleep apnea: brain structural changes and neurocognitive function before and after treatment. Am J Respir Crit Care Med, 183(10), 1419-1426. doi:10.1164/rccm.201005-0693OC

Cano-Pumarega, I., Duran-Cantolla, J., Aizpuru, F., Miranda-Serrano, E., Rubio, R., Martinez-Null, C., . . . Barbe, F. (2011). Obstructive sleep apnea and systemic hypertension: longitudinal study in the general population: the Vitoria Sleep Cohort. Am J Respir Crit Care Med, 184(11), 1299-1304. doi:10.1164/rccm.201101-0130OC

Castronovo, V., Scifo, P., Castellano, A., Aloia, M. S., Iadanza, A., Marelli, S., . . . Falini, A. (2014). White matter integrity in obstructive sleep apnea before and after treatment. Sleep, 37(9), 1465-1475. doi:10.5665/sleep.3994

CDC. (2015). Atrial Fibrillation.   Retrieved from https://www.cdc.gov/dhdsp/data_statistics/fact_sheets/docs/fs_atrial_fibrillation.pdf

Chakhtoura, M., & Azar, S. T. (2012). Continuous positive airway pressure and type 2 diabetes mellitus. Diabetes Metab Syndr, 6(3), 176-179. doi:10.1016/j.dsx.2012.09.013

Chaouat, A., Weitzenblum, E., Krieger, J., Ifoundza, T., Oswald, M., & Kessler, R. (1995). Association of chronic obstructive pulmonary disease and sleep apnea syndrome. Am J Respir Crit Care Med, 151(1), 82-86. doi:10.1164/ajrccm.151.1.7812577

Chen, L., Kuang, J., Pei, J. H., Chen, H. M., Chen, Z., Li, Z. W., . . . Zhang, S. T. (2016). Continuous positive airway pressure and diabetes risk in sleep apnea patients: A systemic review and meta-analysis. Eur J Intern Med. doi:10.1016/j.ejim.2016.11.010

Duran-Cantolla, J., Aizpuru, F., Montserrat, J. M., Ballester, E., Teran-Santos, J., Aguirregomoscorta, J. I., . . . Breathing, G. (2010). Continuous positive airway pressure as treatment for systemic hypertension in people with obstructive sleep apnoea: randomised controlled trial. BMJ, 341, c5991. doi:10.1136/bmj.c5991

Fein, A. S., Shvilkin, A., Shah, D., Haffajee, C. I., Das, S., Kumar, K., . . . Anter, E. (2013). Treatment of obstructive sleep apnea reduces the risk of atrial fibrillation recurrence after catheter ablation. J Am Coll Cardiol, 62(4), 300-305. doi:10.1016/j.jacc.2013.03.052

Ferini-Strambi, L., Baietto, C., Di Gioia, M. R., Castaldi, P., Castronovo, C., Zucconi, M., & Cappa, S. F. (2003). Cognitive dysfunction in patients with obstructive sleep apnea (OSA): partial reversibility after continuous positive airway pressure (CPAP). Brain Res Bull, 61(1), 87-92.

Floras, J. S. (2015). Hypertension and Sleep Apnea. Can J Cardiol, 31(7), 889-897. doi:10.1016/j.cjca.2015.05.003

Giles, T. L., Lasserson, T. J., Smith, B. J., White, J., Wright, J., & Cates, C. J. (2006). Continuous positive airways pressure for obstructive sleep apnoea in adults. Cochrane Database Syst Rev(1), CD001106. doi:10.1002/14651858.CD001106.pub2

Haines, K. L., Nelson, L. G., Gonzalez, R., Torrella, T., Martin, T., Kandil, A., . . . Murr, M. M. (2007). Objective evidence that bariatric surgery improves obesity-related obstructive sleep apnea. Surgery, 141(3), 354-358. doi:10.1016/j.surg.2006.08.012

Heeley, E., Billot, L., Anderson, C. S., Antic, N. A., Neal, B., McEvoy, R. D., & investigators, S. (2016). Statistical analysis plan for the Sleep Apnea cardioVascular Endpoints study: An international randomised controlled trial to determine whether continuous positive airways pressure treatment for obstructive sleep apnea in patients with CV disease prevents secondary cardiovascular events. Int J Stroke, 11(1), 148-150. doi:10.1177/1747493015607504

Kribbs, N. B., Pack, A. I., Kline, L. R., Smith, P. L., Schwartz, A. R., Schubert, N. M., . . . Dinges, D. F. (1993). Objective measurement of patterns of nasal CPAP use by patients with obstructive sleep apnea. Am Rev Respir Dis, 147(4), 887-895. doi:10.1164/ajrccm/147.4.887

Lee, W., Nagubadi, S., Kryger, M. H., & Mokhlesi, B. (2008). Epidemiology of Obstructive Sleep Apnea: a Population-based Perspective. Expert Rev Respir Med, 2(3), 349-364. doi:10.1586/17476348.2.3.349

Liu, L., Cao, Q., Guo, Z., & Dai, Q. (2016). Continuous Positive Airway Pressure in Patients With Obstructive Sleep Apnea and Resistant Hypertension: A Meta-Analysis of Randomized Controlled Trials. J Clin Hypertens (Greenwich), 18(2), 153-158. doi:10.1111/jch.12639

Lyons, O. D., & Bradley, T. D. (2015). Heart Failure and Sleep Apnea. Can J Cardiol, 31(7), 898-908. doi:10.1016/j.cjca.2015.04.017

McEvoy, R. D., Antic, N. A., Heeley, E., Luo, Y., Ou, Q., Zhang, X., . . . Coordinators. (2016). CPAP for Prevention of Cardiovascular Events in Obstructive Sleep Apnea. N Engl J Med, 375(10), 919-931. doi:10.1056/NEJMoa1606599

Mehra, R., Benjamin, E. J., Shahar, E., Gottlieb, D. J., Nawabit, R., Kirchner, H. L., . . . Sleep Heart Health, S. (2006). Association of nocturnal arrhythmias with sleep-disordered breathing: The Sleep Heart Health Study. Am J Respir Crit Care Med, 173(8), 910-916. doi:10.1164/rccm.200509-1442OC

Montesi, S. B., Edwards, B. A., Malhotra, A., & Bakker, J. P. (2012). The effect of continuous positive airway pressure treatment on blood pressure: a systematic review and meta-analysis of randomized controlled trials. J Clin Sleep Med, 8(5), 587-596. doi:10.5664/jcsm.2170

Muxfeldt, E. S., Margallo, V., Costa, L. M., Guimaraes, G., Cavalcante, A. H., Azevedo, J. C., . . . Salles, G. F. (2015). Effects of continuous positive airway pressure treatment on clinic and ambulatory blood pressures in patients with obstructive sleep apnea and resistant hypertension: a randomized controlled trial. Hypertension, 65(4), 736-742. doi:10.1161/HYPERTENSIONAHA.114.04852

Neilan, T. G., Farhad, H., Dodson, J. A., Shah, R. V., Abbasi, S. A., Bakker, J. P., . . . Kwong, R. Y. (2013). Effect of sleep apnea and continuous positive airway pressure on cardiac structure and recurrence of atrial fibrillation. J Am Heart Assoc, 2(6), e000421. doi:10.1161/JAHA.113.000421

O’Donoghue, F. J., Wellard, R. M., Rochford, P. D., Dawson, A., Barnes, M., Ruehland, W. R., . . . Jackson, G. D. (2012). Magnetic resonance spectroscopy and neurocognitive dysfunction in obstructive sleep apnea before and after CPAP treatment. Sleep, 35(1), 41-48. doi:10.5665/sleep.1582

Parra, O., Sanchez-Armengol, A., Capote, F., Bonnin, M., Arboix, A., Campos-Rodriguez, F., . . . Macarron, J. L. (2015). Efficacy of continuous positive airway pressure treatment on 5-year survival in patients with ischaemic stroke and obstructive sleep apnea: a randomized controlled trial. J Sleep Res, 24(1), 47-53. doi:10.1111/jsr.12181

Rotenberg, B. W., Murariu, D., & Pang, K. P. (2016). Trends in CPAP adherence over twenty years of data collection: a flattened curve. J Otolaryngol Head Neck Surg, 45(1), 43. doi:10.1186/s40463-016-0156-0

Roy, S. (2016). 3 CPAP Challenges That May Be Remedied With Accessories. Sleep Review Magazine. Retrieved from http://www.sleepreviewmag.com/2016/09/3-cpap-challenges-accessories/

Russo, V., Di Meo, F., Rago, A., Mosella, M., Molino, A., Russo, M. G., & Nigro, G. (2016). Impact of Continuous Positive Airway Pressure Therapy on Atrial Electromechanical Delay in Obesity-Hypoventilation Syndrome Patients. J Cardiovasc Electrophysiol, 27(3), 327-334. doi:10.1111/jce.12879

Selim, B. J., Koo, B. B., Qin, L., Jeon, S., Won, C., Redeker, N. S., . . . Yaggi, H. K. (2016). The Association between Nocturnal Cardiac Arrhythmias and Sleep-Disordered Breathing: The DREAM Study. J Clin Sleep Med, 12(6), 829-837. doi:10.5664/jcsm.5880

Somers, V. K., White, D. P., Amin, R., Abraham, W. T., Costa, F., Culebras, A., . . . American College of Cardiology, F. (2008). Sleep apnea and cardiovascular disease: an American Heart Association/american College Of Cardiology Foundation Scientific Statement from the American Heart Association Council for High Blood Pressure Research Professional Education Committee, Council on Clinical Cardiology, Stroke Council, and Council On Cardiovascular Nursing. In collaboration with the National Heart, Lung, and Blood Institute National Center on Sleep Disorders Research (National Institutes of Health). Circulation, 118(10), 1080-1111. doi:10.1161/CIRCULATIONAHA.107.189375

Troussiere, A. C., Charley, C. M., Salleron, J., Richard, F., Delbeuck, X., Derambure, P., . . . Bombois, S. (2014). Treatment of sleep apnoea syndrome decreases cognitive decline in patients with Alzheimer’s disease. J Neurol Neurosurg Psychiatry, 85(12), 1405-1408. doi:10.1136/jnnp-2013-307544

Vasquez, M. M., McClure, L. A., Sherrill, D. L., Patel, S. R., Krishnan, J., Guerra, S., & Parthasarathy, S. (2017). Positive Airway Pressure Therapies and Hospitalization in Chronic Obstructive Pulmonary Disease. Am J Med. doi:10.1016/j.amjmed.2016.11.045

Wang, T. Y., Lo, Y. L., Lee, K. Y., Liu, W. T., Lin, S. M., Lin, T. Y., . . . Kuo, H. P. (2013). Nocturnal CPAP improves walking capacity in COPD patients with obstructive sleep apnoea. Respir Res, 14, 66. doi:10.1186/1465-9921-14-66

Wang, X., Bi, Y., Zhang, Q., & Pan, F. (2013). Obstructive sleep apnoea and the risk of type 2 diabetes: a meta-analysis of prospective cohort studies. Respirology, 18(1), 140-146. doi:10.1111/j.1440-1843.2012.02267.x

Wozniak, D. R., Lasserson, T. J., & Smith, I. (2014). Educational, supportive and behavioural interventions to improve usage of continuous positive airway pressure machines in adults with obstructive sleep apnoea. Cochrane Database Syst Rev(1), CD007736. doi:10.1002/14651858.CD007736.pub2

Yaffe, K., Laffan, A. M., Harrison, S. L., Redline, S., Spira, A. P., Ensrud, K. E., . . . Stone, K. L. (2011). Sleep-disordered breathing, hypoxia, and risk of mild cognitive impairment and dementia in older women. JAMA, 306(6), 613-619. doi:10.1001/jama.2011.1115