In addition to today’s resource, please review:
- Clinical Practice Guideline for Diagnostic Testing for Adult Obstructive Sleep Apnea: An American Academy of Sleep Medicine Clinical Practice Guideline [PubMed Abstract] [Full-Text HTML] [Full-Text PDF]. J Clin Sleep Med. 2017 Mar 15;13(3):479-504. doi: 10.5664/jcsm.6506.
- Treatment of Adult Obstructive Sleep Apnea with Positive Airway Pressure: An American Academy of Sleep Medicine Clinical Practice Guideline [PubMed Abstract] [Full-Text HTML] [Full-Text PDF]. J Clin Sleep Med. 2019 Feb 15;15(2):335-343. doi: 10.5664/jcsm.7640.
Today, I review, link to, excerpt from and embed The Curbsiders‘ “#535 Sleep Apnea Update: How to Choose and Interpret Sleep Tests and Prescribe CPAP Therapy”.*
*Burke ARM, Das AM, Williams PN, Watto MF. “#535 Sleep Medicine Update”. The Curbsiders Internal Medicine Podcast. thecurbsiders.com/category/curbsiders-podcast August 10, 2026.
All that follows is from the above resource.
#535 Sleep Apnea Update: How to Choose and Interpret Sleep Tests and Prescribe CPAP Therapy
Transcript available via YouTube
Diagnosis and Management of Obstructive Sleep Apnea
Explore the interpretation of sleep studies in the diagnosis of obstructive sleep apnea. Master treatment of OSA and how to troubleshoot CPAP challenges with Dr. Aneesa Das.
Claim CME for this episode at curbsiders.vcuhealth.org!
Patreon | Episodes | Subscribe | Spotify | YouTube | Newsletter | Contact | Swag! | CME
Show Segments
- Intro and guest bio
- Case from Kashlak
- Definitions
- Sleep Testing and Interpretation
- Management of OSA
- Outro
Disclosures
Dr. Das reports no relevant financial disclosures. The Curbsiders report no relevant financial disclosures.
CME Partner: VCU Health CE
The Curbsiders are partnering with VCU Health Continuing Education to offer continuing education credits for physicians and other healthcare professionals. Visit curbsiders.vcuhealth.org and search for this episode to claim credit.
Sleep Medicine Update Pearls
- Home sleep tests are best done in those that have higher pre-test probability for sleep apnea.
- If a patient with a high pre-test probability has a negative home sleep study, they should be referred for in-lab testing afterwards.
- For in-lab testing, Dr. Das encourages patients to bring their own pillows, comforters, or stuffed animals, and discourages naps and caffeine after 2 PM that day.
- Auto-titrating PAP devices (APAP) [link is to a Google Search] are helpful for initiating CPAP without requiring patients to go to the lab.
- Mandibular advancement devices (MADs) can also be reasonable alternatives particularly in those that cannot tolerate or decline CPAP.
Sleep Medicine Update Show Notes
Definitions
Apnea: Absence of inspiratory airflow for at least 10 seconds (Javaheri 2017).
Hypopnea: Decrease in airflow lasting at least 10 seconds associated with oxygen desaturation or electroencephalographic arousal (Javaheri 2017).
Obstructive sleep apnea (OSA): collapsed or occluded airway causing reduction or cessation of inspiratory airflow while asleep (Javaheri 2017).
Central sleep apnea (CSA): transient reduction in the generation of breathing rhythm by the brain (Javaheri 2017).
Risk Factors and Physical Exam Findings
Dr. Das walks us through history and exam findings that are common in those with OSA. This includes obesity, shirt collar/neck circumference more than 40 centimeters, micrognathia and retrognathia. In particular, she mentions if a patient’s bottom teeth are more than three millimeters behind their top teeth, then that might suggest that their airway is more likely to occlude while sleeping. Dr. Das encourages us to look for crimping at the edges of the tongue which can be seen with macroglossia, putting a patient at higher risk for OSA (Weiss, 2005). A higher Mallampatti is indicative of a more closed off airway which increases risk of OSA (Chang 2018).
Dr. Das recommends the STOP-BANG questionnaire for screening (Tan 2016). The Epworth Sleepiness Scale [link is to a Google Search] is helpful for assessing fatigue particularly in those with mild sleep apnea where treatment is based primarily on symptoms (Johns 1991).
Types of Sleep Testing
The gold standard for evaluation of suspected sleep apnea is overnight polysomnography performed in a sleep laboratory while attended (Qaseem 2014). During these studies, a patient’s EEG and ECG are monitored, airflow is monitored through both chest and abdominal effort, muscle tone (chin EMG) as well as electrooculography are measured to determine whether a patient is in REM sleep. Oximetry, body position, snoring and leg movements are also monitored.
There are four different types or levels of sleep studies determined by the number of physiologic channels being monitored. Type I is an attended in-lab study as above. Type II studies use the same array of monitoring as Type I but are unattended and can occur out of the lab. Type III studies are more limited and typically measure two respiratory parameters (airflow and effort to breathe), oximetry and a cardiac parameter (heart rate or ECG). Type IV tests typically only measure 1-2 parameters including oxygen saturation, heart rate and in some cases airflow (Kapur 2017).
Home sleep monitors are reasonable alternatives to in-lab studies and Dr. Das points out that many insurances are now requiring patients start with a home sleep test due to lower cost. She emphasizes that home sleep tests are best done in those that have higher pre-test probability for sleep apnea. If a patient with a high pre-test probability has a negative home sleep study, they should be referred for in-lab testing afterwards.
Some patients should not do home sleep testing including those with chronic lung disease, chronic heart failure, suspected parasomnias or movement disorders, or neuromuscular conditions as they have not been validated in these populations (Samelka 2016). Dr. Das mentions that those at risk for central sleep apnea such as those on chronic opiates should be referred to in-lab testing rather than home testing. Expert tip: Dr. Das encourages patients to bring something to in-lab sleep testing that helps them sleep comfortably such as pillows or comforters. She discourages naps and caffeine after 2 PM the day of in-lab testing.
A minimum of four hours of quality sleep data is required to make a diagnosis. The data is scored for apneas and hypopneas per hour, which is reported as Apna Hypopnea Index (AHI). Dr. Das explains the new development of 3% vs 4% definitions of AHI. Historically, for something to count as an apnea or a hypopnea on a sleep study, a patient’s oxygen had to drop by 4% or more. However, the American Academy of Sleep Medicine determined this was underestimating sleep apnea so a new definition was incorporated which can define an apnea or hypopnea as a drop in airflow associated with a 3% desaturation or an arousal (though home sleep studies typically not able to report arousal). Sleep studies will report these scores as AHI 3% and AHI 4% respectively. Of note, Dr. Das mentions that women tend to have a lower arousal threshold though they tend to have less significant desaturations. Medicare only acknowledges the 4% definition. The “Aneesa Das approach” is to go by the 4% definition unless there is a big difference or the patient is very symptomatic.
Rather than AHI, some sleep studies may report a Respiratory Event Index (REI) if they do not have a channel to monitor sleep duration (REI is the number of events divided by total study time rather than sleep time).
Another parameter often reported by sleep studies is ODI (oxygen desaturation index) which reports how many times the oxygen drops below a certain threshold. For example, an ODI 4% reports how many times per hour the oxygen saturation has decreased 4%. Recall that an apnea requires cessation of airflow but not necessarily a desat, which can result in difference between AHI and ODI.
Other metrics that may be reported include T90/T88, which show the percentage of sleep time with SpO2 below 90% or 88% respectively.
Dr. Das recommends looking at both proportion of time spent in REM while in sleep as well as sleep position during the study. Airway muscles tend to collapse more during REM sleep so AHI may be worse. Also, AHI is often worse in the supine position, thus if a given sleep study does not capture much time while supine a diagnosis of OSA could be missed. If a person’s overall AHI is normal but their supine AHI is significantly elevated, Dr. Das suggests in-lab testing.
Based on expert consensus, an AHI less than 5 is considered normal, 5-14.9 is diagnostic of mild OSA, 15 to 29.9 is defined as moderate OSA, and at least 30 is considered severe OSA (Gottlieb 2020).
Treatment of OSA
The American Academy of Sleep Medicine recommends treating OSA in those with excessive sleepiness, impaired sleep-related quality of life as well as those with comorbid hypertension (Patil 2019).
First-line treatment of OSA remains positive pressure therapy with CPAP. For patients with OSA who are overweight or obese, lifestyle modification for weight loss should be encouraged. Pharmacologic methods for weight loss such as GLP-1 agonists can be beneficial if appropriate.
Mandibular advancement devices (MADs) can also be reasonable alternatives particularly in those that cannot tolerate or decline CPAP. Dr. Das does mention the importance of utilizing the bite plates that are given alongside MADs to prevent dental misalignment from using the MAD. Pro tip: MADs, if covered by insurance, will be covered by a patient’s medical insurance (not dental insurance), so they should check with their medical insurance for an in-network provider that can make their MAD.
Positional therapy can be considered particularly in those with mild OSA or OSA that is worse while supine. There are various devices on the market that prevent the patient from laying on their back though these have not been compared in head-to-head trials. For a cost-effective option, Dr. Das suggests stuffing a king size pillow into a hiking backpack. The patient could then redo a sleep study to assess the efficacy of the device (or for mild OSA, would assess response primarily by symptoms).
A variety of surgical procedures have been proposed for OSA. In this episode, we briefly discuss neuromodulatory procedures such as hypoglossal nerve stimulation. One meta-analysis showed 74% of CPAP-intolerant OSA patients achieved ≥50% AHI reduction and residual AHI < 20 events/hour using this method (Clemens 2026). Dr. Das suggests reserving this method for those that have tried and were intolerant to CPAP.
CPAP Titration
Traditionally, once a patient was determined to need CPAP, they would be referred to the sleep lab for CPAP titration. During the study, the pressure of the machine would be gradually increased until apneas and hypopneas decreased, the patient’s airway was open and oxygenation was maintained. With the invention of auto-titrating PAP devices (APAP), the machine can measure drops in airflow and sometimes snoring. The machine will increase pressure based on this data automatically throughout the night. Dr. Das typically writes for APAP range starting at 6-16 cmH20. Patients should then follow up for reassessment within 12 weeks so that the range can be adjusted. At that time, typically she typically changes the bottom part of the range to the machine’s reported median used pressure and the top part of the range just below their 95th percentile pressure.
Expert advice: Dr. Das recommends anyone with concerns for hypoventilation such as obesity-hypoventilation, neuromuscular disease, or hypoventilation due to medication (a home study with a significant number of central apneas can be indicative of these processes) should be referred for an in-lab study as they may need a different type of device.
CPAP Trouble Shooting
Dr. Das reviews the importance of mask fit to patient adherence. She reports typically within the first month of getting CPAP in the US, a patient can swap out their mask if it is not fitting properly. After that, they would have to wait three months. Many insurances will stop paying for CPAP if there is not documentation of CPAP adherence by the CPAP machine over the first 3 months so this is a key window. Dr. Das often encourages patients to just watch TV for the first hour that they wear the CPAP for desensitization. If patients find the airflow is too strong, there is a ramp feature that can be enabled to gradually increase pressure as they fall asleep. If a patient finds it is difficult to exhale, there is a expiratory pressure release feature that can be turned on to dip the pressure when the patient breathes out. If patients feel too warm, they may benefit from turning down the humidity. Dr. Das mentions in some cases she will prescribe a sleep aid for the first two weeks a patient uses CPAP.
Maintenance of Therapy
For patients that have well controlled OSA based on their machine’s data, are on stable settings, have a stable weight and are feeling well, there is no role for interval sleep studies for monitoring. Dr. Das recommends repeating a sleep study if there has been significant weight change, development of symptoms or if required to obtain a new machine (e.g. if do not have access to prior study). Guidelines vary for AHI goal during monitoring. Dr. Das aims to have her patients’ average AHI under 5; however, if it is under 10 and their symptoms are controlled she deems this acceptable.
