#123 Sleep Apnea Pearls and Pitfalls

November 5, 2018 | By Cyrus Askin

The sleep apnea episode that won’t put you to sleep. Become a sleep apnea guru with incredible insights from Barbara Phillips MD, MSPH, FCCP an expert in pulmonary medicine, critical care and sleep medicine who is also a past president of CHEST! We discuss high-yield topics in the world of obstructive sleep apnea including: home sleep studies vs in-lab polysomnography, the importance of oxygen saturation (the T90 and ODI) when interpreting sleep study results, tricks to improve CPAP adherence, and alternatives therapies for obstructive sleep apnea. ACP members can visit https://acponline.org/curbsiders to claim free CME-MOC credit for this episode and show notes (goes live 0900 EST).

Full show notes available at http://thecurbsiders.com/podcast. Rate us on iTunes, recommend a guest or topic and give feedback at thecurbsiders@gmail.com.

Credits

Written and produced by: Cyrus Askin MD

CME questions by: Cyrus Askin MD

Editor: Chris Chiu MD & Matthew Watto MD

Hosts: Cyrus Askin MD & Matthew Watto MD

Guest: Barbara Phillips, MD

Cover-Art & Infographic – Beth Garbitelli, MS1

Clinical Pearls

1. Metabolic syndrome and obstructive sleep apnea (OSA) are dangerous bedfellows: Estimates suggest at least 60% of folks with the metabolic syndrome have OSA, although, Dr. Phillips suggests the association could be as high as 80+%! (Parish et al. Journal of Clinical Sleep Medicine, 2007 & Drager et al. PLoS One, 2010)
2. STOP ordering sleep studies on patients who CLEARLY have sleep apnea, if there is anyway to avoid it! In patients with metabolic syndrome who have other signs or symptoms consistent with obstructive sleep apnea (excessive daytime sleepiness, morning headaches, resistant hypertension, large neck diameter) with or without  high scores on the STOP-BANG questionnaire or Epworth Sleepiness Scale, the pre-test probability that they have sleep apnea and would benefit from therapy is high enough to obviate the need for time consuming, expensive testing when we have autotitrating CPAP (continuous positive airway pressure). – Dr Phillips
3. The apnea-hypopnea index (AHI) is not the be-all-and-end-all: The ODI (oxygen desaturation index) and the T90 (time spent, during a sleep study, with an oxygen saturation at-or-lower than 90%) have been shown to be very useful adjuncts to the AHI when evaluating a patient for OSA. Data suggests that it is not the number of hypopneas/apneas but rather the time spent hypoxemic that is most strongly related to the sequelae of sleep apnea. (Chung et al. Anesthesia and Analgesia 2012 & Dr. Phillips)
4. The data for Home Sleep Testing (HST) is growing: Dr. Phillips cited studies to suggest the data from HSTs  is non-inferior to traditional lab-run polysomnography. There is also data that suggests adherence to therapy and improvement in sleepiness is equivalent (if not superior) for patients diagnosed and treated with HSTs and auto-titrating CPAP.  (Chai-Coetzer et al. Annals of Internal Medicine 2017, Chai-Coetzer at al. American Journal of Respiratory & Critical Care Medicine & Berry et al. Journal of Clinical Sleep Medicine 2014)
5. While HST is great, it’s not for everyone: Per the AASM, in lab polysomnography rather than home sleep testing is recommended for patients with “significant cardiorespiratory disease, potential respiratory muscle weakness due to neuromuscular condition, awake hypoventilation or suspicion of sleep related hypoventilation, chronic opioid medication use, history of stroke or severe insomnia.” (Kapur et al. Journal of Clinical Sleep Medicine 2017)
6. Mild OSA may NOT require treatment: Careful reading of the AASM and ATS guidelines on OSA treatment suggests it is reasonable to defer  CPAP therapy for patients with mild OSA who DO NOT endorse excessive daytime sleepiness. Asymptomatic patients with mild OSA who are started on CPAP and have bad experiences may be much more difficult to reach in the future should their disease worsen. (Kushida et al. AASM 2006 &  Chowdhuri et al. ATS 2016)
7. The cost of OSA on society is tremendous: According to the AASM, undiagnosed (and untreated OSA) cost the United States nearly 150 billion dollars in 2015. Of this, 26.2 billion dollars were spent due to car accidents related to sleepiness in the setting of undiagnosed OSA. Nearly 30% of car accidents in the US are associated with drowsy driving which is well-known to be seen in those with sleep apnea. Fortunately, according to the AASM, there is data to suggest that those treated for their OSA are at lower risk. (Hidden Health Crisis Costing America Billions – AASM & AASM Infographic)
8. OSA is a primary care problem: There are not enough sleep medicine doctors to diagnose, treat and manage all the OSA that is out there. Thus, it is a problem that all primary care doctors need to be comfortable with. After all, OSA is not only a potential cause of morbidity and mortality for the patient, but for those the share highways and roadways with them – especially if they go untreated. – Dr. Phillips

Sleep Apnea Show Notes

More pearls from Dr. Phillips

Sleep Apnea – Why should we care?

Dr. Phillips clearly makes the point that OSA is a disease that affects many patients and undiagnosed OSA is a significant public health risk. Diagnosis of OSA, with the emergence of home sleep testing (HST) is easier to achieve than ever and there are many manual and autotitrating CPAP options along with many mask options to better treat patients.

Red flags when screening for obstructive sleep apnea.

Dr. Phillips mentioned excessive daytime fatigue and morning headaches may be suggestive of underlying sleep apnea. A neck circumference of greater than or equal to 17 inches in males and 16 inches in females is an independent risk factor for OSA. Polycythemia may be seen in patients with OSA, however, this is more indicative of concomitant obesity hypoventilation syndrome as it is suggestive of daytime desaturation events.

Sleep apnea demographics

Not everyone with OSA is obese or has the metabolic syndrome. Dr. Phillips reminds us that individuals with hypothyroidism, a receding chin, Down syndrome, Treacher-Collins, folks with a genetic predisposition (such as Chinese populations) and post-menopausal women (due to tissue laxity caused by decreased serum estrogen) are all at higher risk for OSA regardless of their BMI.

Home sleep study

Although there are indications for inpatient sleep studies, the HST is a great option for many. Lab polysomnography is useful for patients with different pre-existing conditions  (see above). However, HST offers certain noteworthy benefits! HST is an inexpensive, fast and easily administered test which uses desaturation events as the primary measurement. The oxygen desaturation index, as well as the T90 (time with oxygen saturation less-than or equal-to 90%) can be determined via an HST and have been shown in the literature to be very useful indicators of disease severity, particularly by the Spanish Sleep Society. Check it! – Consider setting a patient’s auto-titrating CPAP pressure range to 8cm – 16cm H2O as this will capture virtually the full spectrum of potential pressure needs.

Sleep Study Interpretation

The AHI represents the number of times a patient has an episode of complete apnea (stops breathing for 10 or more seconds) + episodes of hypopnea (the definition of which varies) / hour. An AHI < 5 is normal, 6-14 is mild OSA, 15-29 represents moderate OSA and 30+ represents severe OSA. That said, based on data out of the Spanish Sleep Study and other places, the ODI and the T90 may be more clinically useful indicators of disease severity. The ODI represents the number of times oxygen a patient’s oxygen saturation drops from baseline by 4% or more  / hour. The T90 which, according to Dr. Phillips, is most predictive of incident cancer and heart disease, is the number of minutes during a night of sleep where the patient’s oxygen saturation is 90% or lower.

Achieving CPAP Adherence

Improvements in blood pressure and mortality have been shown or suggested in observational studies with some RCT data from Spain that further supports CPAP use can lead to a statistically significant BP reduction. However, the keys to adherence often lie outside of these findings. Dr. Phillips suggested that motivational interviewing can be the key to helping these patients. If a patient suffers with daytime sleepiness, morning headaches or have a spouse won’t sleep in the same room with them due to loud snoring, focusing on these points may be more useful than raw clinical data. Dr. Phillips also commented on picking the right mask for a patient, i.e. the mask the patient will wear. Thus, she recommends having a patient go online to view different mask options and, if possible, try different options to find the one that will maximize CPAP adherence. In patients without a history of insomnia, Dr. Phillips mentioned that sedative-hypnotic drugs may be helpful in facilitating adherence with CPAP, but there is no evidence to suggest they are useful in those with OSA and insomnia.

Alternative to CPAP for OSA treatment

Dr. Phillips discussed interventions for OSA other than conventional, non-invasive  positive pressure therapy. Mandibular advancement devices, custom made by a dentist, can help with the symptoms of sleep apnea in a patient who is resistant to CPAP. These can be difficult to obtain (i.e. costly and time consuming). Other airway adjuncts, such as those that are commercially available, have not shown to be effective. With respect to surgery, bariatric surgery and tracheostomy certainly can benefit a patient with OSA. Outside of these surgeries, other surgical options do not appear to be as beneficial. Dr. Phillips briefly mentioned medications and in doing so, stated that modafinil does have an FDA-approval for residual sleepiness in patients treated for their OSA with CPAP, but it is not an alternative to CPAP.

Conclusion

OSA is a major medical problem that has  significant medical sequelae and a major societal impact. As such, primary care physicians need to be comfortable identifying patients who should be tested for OSA, using strategies to maximize adherence and initiating therapy and managing them over the long term.

Goals and Learning Objectives

Goals

By the end of this episode, listeners will appreciate the emerging significance of obstructive sleep apnea (OSA) for primary care providers, who to screen for OSA, how to evaluate patients, and why treatment of OSA is so crucial.

Learning objectives

After listening to this episode listeners will…

1. Realize the significance of untreated sleep apnea
2. Learn who to screen for OSA and what may suggest an underlying diagnosis
3. Be introduced to sleep apnea therapies aside from CPAP
4. Recall the indications for CPAP and how to appropriately manage these patients
5. Gain insight regarding the future of OSA management and the role of primary care providers in that future

Disclosures

Dr. Phillips reports no relevant financial disclosures. The Curbsiders report not relevant financial disclosures.

Time Stamps

• 00:00 Disclaimer, intro, guest bio
• 03:00 Guest one liner, book recommendation, advice for trainees
• 08:10 Clinical case of sleep apnea, some basic stats, and key predictors of sleep apnea
• 12:38 Barriers to diagnosis and treatment of OSA
• 15:23 Discussion of T90, hypoxemia and sleep fragmentation
• 17:05 How to read a sleep study report
• 21:55 Home sleep apnea testing
• 24:15 What are the consequences of sleep apnea
• 28:30 What is the efficacy of cpap for lowering blood pressure and mortality
• 31:45 Counseling a patient who is new to cpap
• 33:45 Choice of mask
• 40:10 Do alternatives to cpap work? e.g. surgery, mandibular advancement devices
• 44:17 Modafinil and z-drugs
• 47:15 Driver’s license issues in sleep apnea
• 48:35 Future of sleep medicine and take home points
• 51:15 Outro

Recommendation(s) from the guest:

We Die Too Long and Live Too Short (Book – Amazon Link)

Links

Links from the show are included above. Some additional ones referenced…

– Sleep Heart Health Study: https://sleepdata.org/datasets/shhs

– Spanish Sleep Society (Sociedad Española de Sueño): http://ses.org.es