Pushing OSA Guidelines into the Next Decade: Integrating Patient Safety with Perioperative and Precision Based Medicine
By Daniel H. Gouger, MD
Resident Editor, VSA Update Newsletter
VCU Health Department of Anesthesiology

We’ve come a long way in anesthesiology since 1984, when movies like Sixteen Candles, Karate Kid, and Footloose were in theaters. But, the nostalgia of those also reminds us that that was only thirty-seven years ago.

An effort at that time, between the University of Washington at Seattle and the American Society of Anesthesiologists, resulted in the Closed Claims Project to analyze closed malpractice claims and trends in anesthesia-related patient safety topics.

Early data in the 1990s and 2000s showed claims transitioning from surgical anesthesia to chronic and acute pain management, as well as monitored anesthesia care cases. And while regional pain management claims still accounted for approximately twenty percent of cases (even through the late 2000s), respiratory system management issues were still seventeen percent of the mix, with approximately a quarter of those respiratory claims due specifically to inadequate oxygenation and ventilation^.1

The Closed Claims Project (CCP) is a relevant historical narrative for understanding inadequate oxygenation, ventilation, and the emergence of practice guidelines for perioperative management of Obstructive Sleep Apnea. Between CCP data and a rising incidence of case reports over two decades correlating adverse outcomes to poorly optimized OSA, in 2010 an interdisciplinary group of anesthesiologists, surgeons, sleep physicians, and scientists formed the Society for Anesthesia and Sleep Medicine (SASM)².

As a group, they spearheaded the formation of the OSA Near Miss and Death Registry as part of the CCP, as well. Their specific mission in part was, and continues to be, advancing standard of care for perioperative management of sleep disordered breathing.

And while the ASA (among other specialty organizations) had released guidelines in 2006 with updates in 2014, in 2016 SASM sought to publish practice guidelines that underscored evidence of OSA as a perioperative risk factor. These guidelines also offered insight on objective assessment to identify patients with OSA and sought to establish a focused, practical approach to OSA that reduced postoperative adverse events while being thoughtful toward allocation of healthcare resources.^3-4
It’s worth the time, then, to unify some terminology. Sleep Disordered Breathing is an umbrella term for a constellation of sleep related breathing disorders, as well as abnormalities of respiration during sleep that do not meet criteria for a disorder.

In general, there are three characteristics used to describe sleep disordered breathing events: duration, amplitude, and what their end consequences are on oxygen saturation or maintenance of sleep. Using those characteristics, we can describe four types of respiratory events: apnea, hypopnea, respiratory effort related sleep arousals, and snoring.

These events are either centrally mediated events, where there is a lack of inspiratory effort, or obstructive events, where inspiratory effort is maintained or increased in the setting of airway narrowing or collapse, resulting in apneas and hypopneas. Overall, sleep related respiratory events produce increased sympathetic activity/stress, surges in blood pressure, and sleep disruption or fragmentation, as well as hypoxemia.⁵

The concept and physiology of airway obstruction is seemingly straightforward to the anesthesiologist. However, the 2016 Guidelines from SASM underscore that up to ninety percent of patients with moderate to severe obstructive sleep apnea are undiagnosed, and often present for surgical interventions.
SASM further recommends that patients with a diagnosis of OSA should be considered at increased risk for perioperative complications. All adult patients at risk for OSA should be identified before surgery using screening tools such as STOP-BANG, the Berlin criteria, ASA checklist, or other validated screening instruments and questionnaires.

Notably, though, they highlight that there is insufficient evidence to support canceling or delaying surgery to formally diagnose OSA in those patients identified as being high risk of OSA preoperatively unless there is evidence of poorly controlled systemic disease or additional problems with ventilation or gas exchange.⁴

The role of anesthesiologists as perioperative physicians and experts in patient safety becomes pointed, then. Many institutions at this point have implemented streamlined pathways for identification, risk stratification, optimization, and surgical location and resource planning for this patient population.
And while most anesthesiologists at this point are familiar with CPAP therapy, it’s worth pointing out that there are other management approaches. Simple weight loss of 5-10% of starting weight for most OSA patients will yield improvement in their Apnea-Hypopnea Index (AHI).

Although not as common or tolerated as CPAP machines, dental colleagues can fit OSA patients with oral appliances or mandibular advancement devices. Likewise, ENT surgical interventions like turbinate reductions, tonsillectomies and adenoidectomies, uvular reconstruction, or maxillary/mandibular advancements are all considered in some refractory patient populations.

Hypoglossal nerve stimulators which require drug-induced sleep endoscopies to assess oropharyngeal collapse patterns may be considered. Ultimately, though, we still rely on CPAP with guidelines recommending having equipment available for perioperative use or having the patient bring their own.^3-4

Two randomized control trials from 2016, the RICCADSA study by Peker et. al and the SAVE trial by McEvoy et. al, both elucidate some worthwhile points regarding OSA. Night-time CPAP adherence often falls below three and a half to four hours of use, an inflection point at which the potential comorbidity benefits may be lost. This has led to evolution in CPAP fitting technology.

Likewise, OSA may have just as much impact on neuro/cerebrovascular outcomes as it does primary cardiovascular outcomes. But most importantly, these articles suggest that OSA is not a monolithic disease among all patient groups.^6-7

A 2020 review article by Zinchuk et al. in CHEST proposes current guidelines for OSA reflect a one-size fits all approach whereby polysomnographic data are reduced to a single metric, like the Apnea-Hypopnea Index (AHI), and then patients are managed with CPAP trial and error.⁸ Refractory cases may be referred to other treatments like oral appliances, stimulators, or surgical interventions as abovementioned.

But the article suggests different patient populations have varying OSA presentations in snoring and daytime somnolence versus insomnia and restlessness, as examples. Some patients may be at extremes of age, or some may not fit the conventional obese archetype; and these characteristics do not always predictably correlate to severity of the AHI score.⁸

While not yet fully demonstrated as reproducible in high powered studies, the prospect of these OSA “phenotypes” illustrates the potential for tailored approaches to perioperative management for OSA.
For instance, certain subgroups could theoretically benefit from new preoperative referral pathways for early evaluation for oral appliances, surgery, or other medical therapies beyond CPAP. Subgroup typing could justify additional postoperative risk mitigation resources in certain surgical settings or could potentially be paired with other objectively laboratory data points such as hemoglobin and serum bicarbonate to propose new risk stratifying models. Certain subsets of patients may be more at-risk for postoperative cognitive impairment as a cerebrovascular complication rather than typically thought-of cardiopulmonary sequelae.

This tailoring concept is paralleled in the Precision Medicine Initiative by NIH Director Francis Collins.⁹ While first applied to oncologic management, precision medicine is quickly being extrapolated to a whole range of health and disease and undoubtedly will reach perioperative medicine.

So, as we reflect on Guideline updates from 2014-2016 from various specialty societies, the concept of individually varying presentations of OSA should challenge us to consider future optimization possibilities and our roles as anesthesiologists. OSA ultimately is a pathology-centered case model for what our specialty strives for with Enhanced Recovery After Surgery and the Perioperative Surgical Home paradigms.

Figuring out how to marry systems level patient safety and optimization pathways, then, with precision-based medicine principles yields exciting opportunities for anesthesiologists to continue to grow as leaders in perioperative medicine.

References

1. Metzner J, Posner KL, Lam MS, Domino KB. Closed claims’ analysis. Best Pract Res Clin Anaesthesiol. 2011 Jun;25(2):263-76. doi: 10.1016/j.bpa.2011.02.007. PMID: 21550550.
2. Norman Bolden, Karen L. Posner; OSA Death and Near-Miss Registry: SASM and AQI Working to Eliminate Preventable Deaths. ASA Newsletter 2014; 78:56–57
3. American Society for Anesthesiology: Practice guidelines for the perioperative management of patients with obstructive sleep apnea: An updated report by the ASA Task Force on Perioperative Management of Patients with Obstructive Sleep Apnea. Anesthesiology, 2014;120: 268–286.
4. Chung F, Memtsoudis SG, Ramachandran SK, Nagappa M, Opperer M, Cozowicz C, Patrawala S, Lam D, Kumar A, Joshi GP, et al. Society of Anesthesia and Sleep Medicine Guidelines on Perioperative Screening of Adult Patients with Obstructive Sleep Apnea. Anesth Analg. 2016 Aug; 123(2):452-73.
5. Sleep–related breathing disorders in adults: Recommendations for syndrome definition and measurement techniques in clinical research. The Report of an American Academy of Sleep Medicine Task Force. Sleep, 1999 Aug 1.;22(5): 667-689.
6. Peker Y, Glantz H, Eulenburg C, Wegscheider K, Herlitz J, Thunstrom E. Effect of positive airway pressure on cardiovascular outcomes in coronary artery disease patients with nonsleepy obstructive sleep apnea. The RICCADSA randomized controlled trial. Am J Respir Crit Care Med. 2016;194:613–20.
7. McEvoy, R. D. et al. CPAP for prevention of cardiovascular events in obstructive sleep apnea. NEJM. 2016;375,919–931.
8. Zinchuck, A., Yaggi, HK. Phenotypic Subtypes of OSA: A Challenge and Opportunity for Precision Medicine. Chest. 2020 Feb;157(2):403-420. doi: 10.1016/j.chest.2019.09.002. Epub 2019 Sep 17
9. Collins, F.S., and H. Varmus. 2015. A new initiative on precision medicine. New England Journal of Medicine 372 (9): 793–795 https://doi.org/10.1056/NEJMp1500523.