Introduction
Obstructive sleep apnea (OSA) is a state-dependent phenomenon in which the pharyngolarynx undergoes repetitive obstruction. For the otolaryngologist, the ability to phenotype the specific site(s), anatomic structures, and patterns involved in the upper airway obstruction appears crucial to successful outcomes.
Upper airway evaluation in a sedated state was first published by Croft and Pringle in 1991. Since that description, drug-induced sedated endoscopy (DISE) has demonstrated moderate-to-substantial inter-rater reliability and discriminant validity between snorers and non-snorers. Patients undergoing DISE have been noted to have significantly more severe velopharyngeal and hypopharyngeal collapse than that observed during awake endoscopy with Müller maneuver.
However, there are several important limitations, including a learning curve for the otolaryngologist and anesthesiologist to obtain the optimal plane of sedation, nonnatural sleep, variability in technique and staging systems, and the lack of quantitative measurements.
Key Operative Learning Points
- 1.
Proper technique and depth of sedation are critical to approximate natural sleep.
- 2.
DISE provides an opportunity for dynamic assessment of the airway during a sleep-disordered breathing state and the effect of mandibular repositioning or other interventions.
- 3.
The role of DISE is an adjunctive diagnostic tool to improve surgical decision making and outcomes, rather than a surgical roadmap in isolation.
Preoperative Period
History
- 1.
History of present illness
- a.
Presence of common sleep disorders, such as insomnia and restless legs syndrome. Failure to treat these disorders will result in suboptimal outcomes.
- b.
Subjective benefit from previous weight loss, positional therapy, oral appliance, or positive airway pressure (PAP) implicates OSA as driving force behind symptomatology.
- c.
In-depth review of most recent diagnostic sleep study with attention to positional or stage-related differences. DISE is considered to largely resemble non-REM rapid eye movement sleep.
- a.
- 2.
Past medical history
- a.
Prior surgical otolaryngology treatment
- b.
Comorbidities associated with OSA: diabetes, hypertension, stroke, myocardial infarction, arrhythmia, depression, obesity
- c.
Difficulty with entrance or emergence from anesthesia
- a.
Physical Examination
- 1.
Anterior rhinoscopy
- a.
Septal deviation, turbinate hypertrophy, and nasal polyps: These structures can create proximal obstruction, thereby increasing negative pressure in the distal pharynx.
- a.
- 2.
Facial skeleton evaluation
- a.
Significant maxillary or mandibular constriction may require skeletal correction.
- a.
- 3.
Neck exam
- a.
Inferiorly positioned hyoid bone (greater than two fingerbreadths below mandibular plane) intimates an unfavorably elongated airway; treatment options must be tailored to this phenotype.
- a.
Imaging
- •
None—although DISE findings may be correlated with existing imaging results
Indications
Surgical evaluation for sleep apnea requires synthesis of patient’s OSA symptoms, medical history, physical exam (including awake nasolaryngoscopy), sleep study results, patient preference, and patient expectations. If these elements are favorable for surgical treatment, the DISE can be performed as a planning tool either as a standalone procedure or immediately prior to surgical therapy in the operating room. Common indications include:
- 1.
To plan a multilevel upper airway surgical plan in patients who have failed medical device therapy and present with concern for multilevel or multifactorial airway collapsibility
- 2.
To evaluate the upper airway after prior failure of airway reconstructive surgery
- 3.
To evaluate for anatomic candidacy for hypoglossal nerve stimulation therapy. At present, the Inspire hypoglossal nerve stimulator is the only surgical therapy that requires a priori DISE evaluation for candidacy determination. This requirement is related to indication guidelines from the US Food and Drug Administration.
- 4.
At the time of staged or adjunctive nasal surgery, DISE to evaluate the rest of the upper airway anatomy should additional surgical considerations be needed in the future
- 5.
In patients who achieve partial but incomplete results with oral appliance therapy, DISE with and without the oral appliance to evaluate for residual locations of collapse and additional medical or surgical treatment options to further augment the effectiveness of the oral appliance
- 6.
In patients with persistent apnea-hypopnea index elevation or other evidence of airway obstruction despite CPAP (continuous positive airway pressure) use, DISE with and without the CPAP in place to investigate the reasons for CPAP failure, such as epiglottic collapse or iatrogenic airway obstruction due to the interface impact on the jaw and neck position
- 7.
In the pediatric population, to evaluate for persistent OSA after adenotonsillectomy and other first-line therapy. DISE is often preferred to in-office awake laryngoscopy for both patient tolerability and visualization of dynamic collapsibility.
Contraindications
- •
History of drug allergy to sedating agent
- •
Pregnancy
- •
Significant nasal obstruction precluding endoscopic examination
Preoperative Preparation
- •
No food or drink after midnight because the patient is receiving general anesthesia
Operative Period
Perioperative Medications
- 1.
Fifteen minutes prior to the procedure, the patient is given 0.2 to 0.4 RCD mg intravenous glycopyrrolate (depending upon ideal body weight) to decrease oronasal secretions.
- 2.
Topical oxymetazoline 0.05% and/or lidocaine 4% solution or 2% jelly are applied unilaterally to the more patent entry nostril.
- 3.
No antibiotic prophylaxis is required.
Positioning
- 1.
At the outset, supine position with one pillow under the head. Positioning changes over the course of the procedure (see “ Surgical Technique ” later).
- 2.
Do not tuck the arms because this may lead to increased combativeness.
- 3.
Place blow-by oxygen below chin for supplemental oxygen reservoir, if needed, without interfering with scope placement.
Anesthesia
- 1.
Propofol
- a.
Most commonly used agent with rapid sedation/emergence profile
- b.
Continuous infusion started at 100 to 150 μg/kg/minutes and gradually titrated based on clinical parameters of sedation
- c.
Boluses of 100 to 300 μg/kg optionally added as needed depending on surgeon judgment and patient sedation
- a.
- 2.
Alternative agents include midazolam and dexmedetomidine.
Monitoring
- 1.
Pulse oximetry
- 2.
Blood pressure cuff
- 3.
Five-lead EKG electrocardiogram monitoring
- 4.
Bispectral index (BIS) monitoring is optional but may serve as a useful adjunct to determine proper depth of sedation. BIS range of 57 to 71 has been reported to correlate with the collapsibility and loss of genioglossus muscle activity seen in OSA.
Instruments and Equipment to Have Available ( Figs. 52.1 and 52.2 )
- 1.
Laryngoscope tower with audio and video recording capability
Fig. 52.1
Nasal medications, including oxymetazoline and lidocaine jelly with cotton-tipped applicators.
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