Butkov’s article, “Misdiagnosed Sleep Apnea” raises important issues regarding automated scoring.1 Failure to account for artifacts, inaccurate diagnoses, and less thorough analyses may arise. However, we were confused by the case example presented and perplexed by the apparent reluctance to consider the utility of advanced modes of PAP therapy.

The patient in question was a 62-year-old female with a BMI of 35, neck circumference of 34 inches, and a moderately large tongue and crowded oropharynx. Additional medical history included fibromyalgia, hypothyroidism, fatigue, and reflux, and all these signs and symptoms would generate a high index of suspicion for the diagnosis of obstructive sleep apnea (OSA) or upper airway resistance syndrome (UARS). Indeed, according to Gold’s research on women with fibromyalgia, 27 of the 28 women manifested sleep-disordered breathing (SDB) with one exhibiting OSA and 26 exhibiting inspiratory flow limitation with arousals (UARS).2 Thus, with all due respect, we doubt the case reflects a misdiagnosis; instead, the original sleep center may have scored too many hypopneas (AHI=29), thereby disguising the likelier diagnosis of UARS.

UARS is a clinically recognized sleep condition included in the nosology of the American Academy of Sleep Medicine under the heading of obstructive sleep apnea and includes a distinct respiratory event known as a respiratory effort-related arousal (RERA).3 Accordingly, we were nonplussed by the author’s reference to Medicare criteria regarding UARS, because Medicare’s failure to use evidence-based scientific findings to determine policies on UARS have no bearing, other than financial, on standard clinical assessment and treatment of sleep patients with this OSA variant. In contrast, the AASM not only recognizes UARS (subsumed within OSA nosology), but also the Academy’s practice parameters mandate the elimination of such events during titration treatment procedures.4 Yet, no mention was made by the author on whether UARS was assessed with a pressure transducer during the repeat diagnostic study.

Sleep professionals are ethically bound to treat UARS as standard of care. When UARS causes daytime sleepiness or fatigue or exacerbates fibromyalgia flare-ups, we would never say to such patients, “Since Medicare does not cover treatment of UARS, you don’t have a sleep breathing disorder.” Doing so would constitute clear-cut medical mis-practice; and, if the patient suffered harm from this misdirection, then the failure to diagnose and treat UARS would constitute medical malpractice. For example, if a UARS patient suffered from severe daytime sleepiness but was not informed of the diagnosis and treatment options due to “robotic” adherence to Medicare policies, the sleep physician would face severe exposure were this patient to fall asleep at the wheel and injure herself or others.

One final concern was the use of the term “over-titrated” to describe the patient’s previous lab encounters; perhaps, it is just as likely the previous sleep techs were following AASM guidelines by attempting to titrate out inspiratory flow limitations, a process that may trigger expiratory pressure intolerance and subsequent central apneas. If the central apnea index (CAI) >5 and the CAI/AHI >50%, the patient would have then met diagnostic criteria for complex sleep apnea for which ASV therapy would be appropriate treatment.5 Thus, the term “over-titrate” is inaccurate, because the tech must increase pressures to treat UARS to normalize the patient’s breathing, regardless of whether this step leads to an optimal titration or the necessity for switching to more advanced PAP therapy modes. In contrast, we are informed only that the patient was prescribed ASV, not whether she was ever titrated with the device in a sleep lab. And it appears no attempt was made to help the patient adjust to PAP therapy in general, regardless of the mode, which could have been a reasonable first approach to her care.

In summary, based on the original information of a likely postmenopausal and morbidly obese woman presenting with the additional history that would predict a greater than 90% chance of sleep-disordered breathing coupled with one lab documenting an AHI of 29, we submit this patient’s “missed diagnosis” was the failure to recognize her UARS; her intolerance to standard PAP therapy; and her need for ample coaching or titrations to effectively use what might have proven to be definitive treatment with an ASV device.

Although there is a legitimate argument this type of patient may never respond to PAP therapy, it does not follow she would be given the sole diagnosis of “sleep maintenance insomnia” and offered only cognitive behavioral therapy (CBT). In our clinical experience, we see many “sleep maintenance insomnia” SDB cases—what we term “complex insomnia”;6 and, as described in an article published in the same issue of Sleep Review as Butkov’s piece, we detail how we successfully titrate these difficult cases with advanced modes of PAP therapy such as auto-bilevel and adaptive servo-ventilation devices.7 Let us then close by saying how impressed and how grateful we are to the leading manufacturers of PAP therapy devices that have worked so diligently and scientifically (irrespective of the resistance they must fend off in bringing their new technology to market) to develop auto-adjusting algorithms, which advance their humanitarian efforts to aid millions of individuals to overcome their struggles with pressurized airflow machines.


Jessica Sanchez, RPSGT, lead technologist; Shara Kikta, RPSGT, lab manager; and Barry Krakow, MD, medical director, are staff at Maimonides Sleep Arts & Sciences Ltd. The authors can be reached at [email protected]

REFERENCES (SANCHEZ)

  1. Butkov N. Misdiagnosed sleep apnea: is positive airway pressure therapy overused? Sleep Review. 2011;12(8):24-7.
  2. Gold AR, Dipalo F, Gold MS, Broderick J. Inspiratory airflow dynamics during sleep in women with fibromyalgia. Sleep. 2004; 27(3):459-466.
  3. American Academy of Sleep Medicine. International Classification of Sleep Disorders: Diagnostic & Coding Manual. 2nd ed. Westchester, Ill: American Academy of Sleep Medicine; 2005.
  4. Kushida CA, Littner MR, Hirshkowitz M, et al. Practice parameters for the use of continuous and bilevel positive airway pressure devices to treat adult patients with sleep-related breathing disorders. Sleep. 2006;29(3):375-380.
  5. Krakow B, Romero EA, Ulibarri VA, Kikta S, Thomas RJ. ASV therapy in anxious or insomnia patients with complex sleep apnea. Sleep (Abstract Supplement). 2010; 33:A146.
  6. Krakow B, Melendrez D, Pedersen B, et al. Complex insomnia: insomnia and sleep-disordered breathing in a consecutive series of crime victims with nightmares and PTSD. Biol Psychiatry. 2001;49(11):948-953.
  7. Krakow B. Paving the way to optimal titrations: the PAP-NAP: a titration by any other name. Sleep Review. 2011;12(8):14-21.
  8. Butkov N. Misdiagnosed sleep apnea: is positive airway pressure therapy overused? Sleep Review. 2011;12(8):24-7.
  9. Kushida CA, Chediak A, Berry RS, et al. Clinical guidelines for the manual titration of positive airway pressure in patients with obstructive sleep apnea. J Clin Sleep Med 2008;4:157-171.

AUTHOR RESPONSE

I would like to thank Jessica Sanchez, RPSGT, Shara Kikta, RPSGT, and Barry Krakow, MD, for their response to my article “Misdiagnosed Sleep Apnea” in the October issue of Sleep Review.1 I agree with the authors that the patient described in the case review had a clinical history suggestive of possible obstructive sleep apnea (OSA) or upper airway resistance syndrome (UARS), and I also agree that UARS is a clinically recognized sleep condition that warrants consideration and treatment. However, this patient had neither OSA nor UARS. As noted, her sleep was well-consolidated with very few disturbances of any type. Although she had reduced sleep efficiency, she had very few arousals, as documented during both NREM and REM sleep in supine and lateral body positions. Our sleep center is very cognizant of the manifestations of UARS and there was no evidence of UARS on her study.

When I stated that this patient did not qualify for CPAP, I did not imply that UARS should be ignored. Our sleep center has encountered many situations when patients with UARS did not qualify for treatment under Medicare policy and we did not tell these patients that they “do not have a sleep disorder.” But we have also seen many patients who have been misdiagnosed with OSA or UARS for the reasons described in my article. My remark that this patient did not qualify for CPAP was made in reference to actual clinical indicators, not Medicare policy.

I would also like to comment on the topic of inspiratory flow limitation and respiratory effort-related arousal (RERA) in the context of CPAP titration. Flow limitation is a term commonly used to describe a “flattening” pattern in an airflow signal derived from a pressure sensor interfaced with a nasal cannula or CPAP mask. However, an airflow pattern suggestive of flow limitation alone does not constitute a RERA because an airflow sensor measures neither effort nor arousal. Moreover, a “flattening” of the signal (regardless of the type of transducer used) is not always indicative of flow limitation. Changes in the size and shape of the signal can be associated with normal respiratory variants or they might be artifacts. Problems with over-scoring or over-titrating invariably arise when too much emphasis is placed on signals derived from any one particular sensor without seeing the bigger picture. Whereas experienced technologists know how to correlate suspected flow limitation with the EEG, many do not and instead rely strictly on respiratory parameters and oximetry when making titration decisions.

The current recommendations by the American Academy of Sleep Medicine (AASM) state that “exploration” of CPAP above the pressures at which control of respiratory abnormalities is achieved can be made if it does not exceed 5 cm H2O.2 In most instances, residual RERAs can be eliminated by only slight increases in pressure (1-2 cm H2O) above the threshold of apnea and hypopnea. The practice of continually increasing pressures for perceived flow limitation becomes counterproductive if it leads to exacerbation of central apneas or causes an increase in sleep disturbance. Problems with over-titration are especially common when working with patients who have poor quality sleep. Differentiating arousals that result from respiratory disturbances versus respiratory signal distortions caused by body movements or preceding arousals can be a challenging exercise that requires careful examination of all relevant parameters. However, the patient described in my article did not present these challenges and I stand by my observation that she was over-titrated. Her subsequent label of “complex sleep apnea” (a term that has emerged with the advent of adaptive servo-ventilation, but has never been adequately defined in terms of etiology or clinical significance) is equally incongruous considering she had no significant respiratory disturbance in the first place.

Finally, I agree that we are indebted to the makers of positive airway pressure (PAP) equipment for their innovation and continued support of the field, but I believe we must also be careful not to arbitrarily adopt industry-based definitions, titration protocols, auto-adjusting algorithms, and scoring formulas without careful scrutiny. In the case presented by my article, the patient was not well-served by either the diagnostic or treatment technologies. The use of PAP therapy only made it more difficult for her to sleep and it did not alleviate her symptoms. We are increasingly seeing this phenomenon, particularly in light of the ever-increasing push toward diagnostic portability, automation, and rapid assignment to treatment. In the same manner as so many patients in the present day are over-medicated, we are beginning to see a similar trend toward over-prescribing various forms of PAP therapy to patients who might instead benefit from simple lifestyle changes, or other common sense measures that might improve both quality of life and sleep.


Nic Butkov, RPSGT, is education coordinator at the Rogue Valley Sleep Center, CEO of Synapse Media Inc, and director of the School of Clinical Polysomnography in Medford, Ore. He can be reached at [email protected]

REFERENCES (BUTKOV)

  1. Butkov N. Misdiagnosed sleep apnea: is positive airway pressure therapy overused? Sleep Review. 2011;12(8):24-7.
  2. Kushida CA, Chediak A, Berry RS, et al. Clinical guidelines for the manual titration of positive airway pressure in patients with obstructive sleep apnea. J Clin Sleep Med 2008;4:157-171.