Significant updates have been made to the original Stanford sleep surgery algorithm to reflect increased understanding of obstructive sleep apnea pathophysiology, patient phenotyping, and treatment outcome.
Overall treatment success of the patient is more important than individual surgical success.
The new algorithm focuses on precision in patient selection, procedural selection, and procedural accuracy.
Positive airway pressure therapy plays a significant role in the surgical algorithm.
Multilevel surgery or maxillomandibular advancement in combination with upper airway stimulation may achieve long-term cure.
How to approach a patient seeking surgery for obstructive sleep apnea?
A 52-year-old man with severe obstructive sleep apnea (OSA) and a history of septoplasty and uvulopalatopharyngoplasty (UPPP) seeks further care. Surgical options for him are not similar to those for a 22-year-old woman with mild OSA but presenting with equally debilitating daytime sleepiness and mood disturbance. What about a 64-year-old man with a history of nasal, palate, and maxillomandibular advancement (MMA) surgery 2 decades ago who now presents with moderate OSA? And what should be done with a patient with an apnea-hypopnea index (AHI) greater than 140 events per hour with normal body mass index (BMI), who is intolerant to continuous positive airway pressure (CPAP)?
Clearly, a surgical algorithm needs to be as patient-specific as possible, while incorporating all the established interventions in a systematic fashion.
Before presenting an updated sleep surgery algorithm based on 3 decades of experience at Stanford, several important points need to be made. They are the context through which the algorithm is conceived.
Why do we need an updated algorithm?
Only one of the many OSA mechanisms is reliably addressed by surgical interventions : Airway critical closing pressure .
Interventions provided, including CPAP, affect airway critical closing pressure. There are other important mechanisms, including respiratory arousal threshold, muscle tone, and loop gain, which cannot be addressed directly by surgery. Furthermore, loss of airway patency during sleep can be obstructive, mixed, or central in origin. Surgery mainly impacts obstructive apnea and hypopnea. Hence, a lot of humility must go into a surgeon’s approach to OSA.
The classic definition of “surgical success” is inadequate .
A frequently asked question is, “How successful is this surgery?” Literature has focused on surgical success, defined as AHI less than 20 events per hour or a decrease of more than half of the baseline AHI. Is surgical success based on AHI adequate?
First, the AHI needs to be interpreted with caution. The definition of hypopnea has changed several times from 1999 to 2012, and generally the definition has become more inclusive. In addition, there is inter-rater inconsistency in the interpretation of hypopnea.
Second, it is increasingly difficult to obtain insurance approval for in-lab, attended polysomnography. Home sleep studies have become more common. The latter tend to present with lower AHI.
Lastly, even the definition of surgical success has variation. Depending on the hypopnea and the surgical success criteria used, the same operation can be reported, with a success rate ranging from as low as 38.9% to as high as 91.7%.
Surgery can significantly decrease the burden of OSA, a chronic condition .
What patients need to be counseled on is that OSA and sleep-disordered breathing present on a continuum of severity and symptoms. It means that OSA can and does recur. It is a matter of how much and when. A relapse of 5 additional events per hour from AHI of 7 versus 70 does not have the same implications. This can be likened to playing field position in American football. The odds of scoring a touchdown is better when you are in the opposing team’s red zone rather than your own.
The patient chooses the procedure .
Assuming the surgeon is able to offer or refer the full spectrum of contemporary sleep apnea surgery, it is still the patient who decides what procedure to undergo. A patient may be a logical candidate for MMA, but, if that is declined, it does not mean that surgeons cannot help with a combination of nasal and palate procedures followed by upper airway stimulation (UAS) of the hypoglossal nerve. A patient who is a good bariatric surgery candidate may decline that operation, but opt for nasal surgery to improve CPAP adherence. Sleep apnea surgery is elective; therefore, the surgeons’ job is to maximize the treatment efficacy in every chosen option.
What is precise about the updated algorithm?
The updated algorithm adds precision in 3 areas.
Precision in patient selection with greater understanding of OSA pathophysiology and the use of diagnostic tools, such as drug-induced sedation (sleep) endoscopy (DISE) ( Fig. 1 ).
Precision in introducing new procedures, such as UAS of the hypoglossal nerve or adult maxillary expansion (distraction osteogenesis maxillary expansion [DOME]), for previously unaddressed patient phenotypes (see Fig. 2 ).
Precision in performing established procedures with more accuracy and consistency. This includes tissue-sparing pharyngoplasty, transoral robotic surgery for lingual tonsillectomy, and virtual surgical planning (VSP) for skeletal procedures (see Fig. 2 ).
A brief word about the original Riley-Powell Stanford algorithm is interesting and important. Robert Riley and Nelson Powell obtained dental degrees from the University of California, San Francisco. They both obtained medical degrees, and Robert Riley also completed an oral and maxillofacial surgery residency at the University of California, Los Angeles. They became residents of otolaryngology at Stanford University. At this time, care for OSA patients entered a dynamic era. Stanford is the pioneering grounds of sleep medicine and research, with the world’s first dedicated sleep clinic under Bill Dement. He first described rapid eye movement sleep. Dr. Dement then recruited Christian Guilleminault, who first introduced sleep apnea. Because the former Stanford otolaryngology and sleep medicine clinics were in the same building, the proximity and expert synergy among Guilleminault, Riley, and Powell produced the original Stanford sleep surgery algorithm. In the early 1990s, having the vision and capability to address both soft tissue and skeletal anatomic risk factors of OSA were defining for the field. Riley and Powell achieved high success and cure rates with patients going through phase 1 surgery—nasal, palate, and genioglossus advancement—followed by phase 2 surgery—MMA ( Fig. 1 ).
In contrast to the linear nature of the former Stanford algorithm, the new algorithm is on a continuum ( Fig. 2 ). Specifics of each procedure are in other articles of this issue. This article serves as a formal introduction to the authors’ current approach to sleep surgery patients.
How to optimize PAP or oral appliance therapy?
To begin, even if a patient is referred for surgery, a careful history about positive airway pressure (PAP) therapy needs to be undertaken. This is after having conducted a careful medical history as well. Patients with significant medical comorbidities or predominant central apnea are better treated with PAP therapy. A thorough nasal evaluation becomes critical, because treating nasal obstruction has been shown to decrease PAP pressure or increase adherence to PAP. Septoplasty, inferior turbinate reduction, and/or nasal valve stabilization plays a significant role in acceptance and adherence to PAP. Nasal evaluation should not end with anterior rhinoscopy, because approximately 27% of patients who cannot tolerate PAP present with posterior septal deviation that can be seen only by nasal endoscopy. This again is addressed with nasal surgery.
Less noticed as a key intervention for nasal obstruction is maxillary expansion. As evidenced in the pediatric literature, changing a high arched palate to a dome-shaped palate via rapid maxillary expansion treats nasal obstruction and OSA. The increase in nasal floor surface area decreases resistance through the internal nasal valve. Beyond improved nasal breathing, this also allows more intraoral volume for the tongue. In 2015, Liu et al started performing adult maxillary expansion, described as DOME. DOME expands the nasal floor, increases the internal nasal valve angle, and decreases nasal resistance both objectively and subjectively in adults.
Improving nasal breathing has an impact on not only PAP therapy but also oral appliance therapy (OAT). Although there are devices built to allow oral breathing, establishment of nasal breathing during sleep leads to more stable air flow and proper neurophysiologic effects on airway dilator muscles and improves sleep quality.
For patients with elevated BMI, both medical and surgical management have significant roles. Surgical intervention requires a period of maximal medical therapy; hence, referral to bariatric experts does not necessarily mean gastric bypass surgery. This can be helpful when counseling patients who are anxious about surgery as referrals are made.
Assuming patients have exhausted their PAP trial and evaluation, as described previously, and are willing to undergo surgery for OSA, the authors’ sleep surgery algorithm continues as follows.