Drug-induced sleep endoscopy (DISE) is an evaluation procedure designed to evaluate the pattern of airway obstruction in the throat in patients with obstructive sleep apnea. DISE is required to determine eligibility for treatment with the Inspire Upper Airway Stimulation technology. A number of amazing colleagues came together for a large, multicenter study published in 2021 showing that specific preoperative DISE findings were associated with Inspire outcomes, with two key findings:

• Complete blockage of breathing related to the tongue was associated with better outcomes
• Complete airway obstruction related to the sides of the throat (oropharyngeal lateral walls) was associated with poorer outcomes

Navigating the FDA’s Expanded BMI Eligibility for Inspire Therapy

Since that time, the FDA has widened their approval for Inspire to include an upper limit of 32 to 40 kg/m2, but very little research has examined who might be the best candidates in this greater-BMI group. Importantly, body mass index has emerged as a key factor associated with Inspire outcomes, in that greater body mass index was associated with poorer outcomes in a number of studies, including the ADHERE Registry involving multiple centers and supported by Inspire themselves.

Phillip Huyett, MD was the lead author on the DISE-Inspire study I just mentioned, and he completed this during his fellowship training at USC when I was there. He has now conducted numerous studies related to Inspire, including a study just accepted for publication in the American Journal of Respiratory and Critical Care Medicine. For this study, Dr. Huyett and his team combined the database from our previous study with an even-larger number of his own patients to examine the connections between body mass index, DISE findings, and Inspire outcomes. They first separated the study population based on DISE pattern of obstruction: anteroposterior (soft palate or tongue falling backwards) or lateral (sides of the throat collapsing inwards). Next they calculated three measures of Inspire outcomes. Their analysis demonstrated the following:

• In those with anteroposterior collapse, body mass index was not associated with Inspire outcomes
• In those with lateral collapse, greater body mass index was associated with notably poorer Inspire outcomes

As a coauthor on this thoughtful and, I believe, important study, I was fortunate to participate in the review of the statistical analysis and discussion of their impact even before the study was published. My takeaway is that this study refines our understanding of the patient population where Inspire outcomes may not be quite as good. Inspire therapy may still be that patient’s best option for treating their obstructive sleep apnea, as they may not able to tolerate CPAP comfortably and may not tolerate or achieve success with an oral appliance. However, this research is critical for having informed discussions with patients about treatment expectations.