DRUG-INDUCED SLEEP ENDOSCOPY

1. DRUG INDUCED SLEEP ENDOSCOPY:
A DIAGNOSTIC
Rashu Mittal
M.S.ENT

2. Obstructive Sleep Apnea Hypopnoea
Syndrome
• Characterized by intermittent episodes of complete or
partial upper airway obstruction during sleep due to:
 pharyngeal muscles hypotonia
and
 increased intracavitary negative pressure during
inspiration associated with the supine position.
• This leads to pharyngeal walls collapse and a patency
reduction of retro palatal and/or retro lingual region
with an increase in airflow resistance.

3. BACKGROUND
• Although CPAP is considered to be the best non surgical
treatment modality, however Compliance is a big issue .
• For other surgical modality (Except Bimax advancement,
rarely tracheostomy) albeit less satisfactory, they requires
precise location of the obstruction.
• Classically, indications are founded on clinical examination
with flexible endoscopy; other methods(Cephalometry, CT,
MRI) are also available, but all have the drawback of being
performed with the patient awake.

4. BACKGROUND
• Since OSAS is a problem related to sleep, the
ideal evaluation technique would be an
assessment of breathing, sleeping patients, as
this would provide a real-time, dynamic
assessment.
• However, these efforts are generally abandoned
due to the discomfort experience by patients,
particularly with movement of the endoscope to
view multiple areas of the pharyngeal airway.

5. INTRODUCTION
• Introduced by Croft & Pringle in 1991 as Sleep
Nasendoscopy.
• Drug-induced sleep endoscopy (DISE) is an upper
airway evaluation technique with 3 key features:
1. the use of pharmacologic agents to achieve
sedation,
2. the target depth of sedation as approximating
natural sleep as much as possible, and
3. the endoscopic evaluation of the upper airway.

6. INDICATIONS
DISE should be performed in patients:
• affected by socially disturbing snoring and OSAHS, in
whom non-CPAP therapy is considered .
• failed CPAP therapy or who encounter difficulties in
tolerating CPAP, as reasons for failure or difficulty in
tolerating CPAP could be potentially highlighted.
• patients in whom previous surgery has failed and may
allow the clinician to recommend either OAT or further
surgical intervention addressing the relevant
anatomical segment that may be causing residual
symptoms

7. WHERE TO PEFORM?
DISE can be performed in any safe clinical setting such as:
 Operating theatre
 Endoscopy room
 Clinical room/Office
• set up with standard anaesthetic equipment (basic monitoring and
resuscitation kits in case of emergency), and where relevant
ambience such as silence and darkness is available.
• DISE can usually be performed as a day-casewhile, in rare cases,
overnight stay may be necessary depending on the patient’s general
condition and if surgical therapy has been concurrently performed.

8. PHYSIOLOGY
• Control of the depth of sedation is essential. The sedative agent will
generally be administered intravenously at the minimum dose to
achieve the target depth of sedation: the loss of consciousness,
defined as loss of response to verbal stimulation at a normal
conversational volume.
• Unconscious sedation represents a lesser degree of neural
depression than anesthesia and may be a closer approximation to
natural sleep.
• The interest in the transition from wakefulness to unconscious
sedation is based on the concept of a thalamocortical switch
determining consciousness or unconsciousness (no response to
verbal stimulation that may be common to natural sleep and
sedation.

9. Sedative Agents

10. Propofol Infusion
• Most detailed studied pharmacological agent (Effects are most closer to
what happens during natural sleep).
• Some surgeons use a protocol involving continuous infusion (usually
unconscious sedation requires 100–150 μg/kg per minute), with possible
additional boluses (e.g., 20–50 mg).
• Other surgeons prefer using a continuous infusion without administration
of boluses.
• Target Controlled Infusion (more accurate, not available at every centre)
• It is important that different individuals can require markedly different
dosages of propofol to reach the target depth of sedation.

11. Target Controlled Infusion
• TCI system has been developed to provide improved
convenience and control during intravenous
anesthesia.
• The basic principle is that the anesthetist sets and
adjusts the target blood concentration and depth of
anesthesia as required on clinical grounds.
• TCI technology uses different pharmacokinetic
modeling to control the infusion rate of the pump,
which allows for a direct control of the sedative agent
brain concentration rather than its blood concentration

12. INTERACTION
• Studies reported that propofol did not change
the respiratory pattern nor significantly
influence the apnea-hypopnea index (AHI),
but did interfere with the sleep architecture,
specifically a reduction in rapid eye movement
(REM) sleep.

14. Bispectral index
• The most important evaluation of the depth of sedation is
clinical, through the onset of snoring, disordered breathing
events, and the loss of consciousness.
• Bispectral index (BIS) score may provide additional monitoring
of sedation. It provides direct information on the effects of
anesthetics and sedatives on the brain by placing a sensor on
a patient’s forehead. The BIS monitor translates the
information from electrical brain activity into a single number
starting from 100 (indicating an awake patient) down to 0
(indicating the absence of brain electrical activity).
• The pursuited value during DISE ranges from 50 to 70.

15. EXAMINATION
• VOTE CLASSIFICATION (V=velum, O=oropharynx,
T=tongue base, E= epiglottis; level, configuration
& degree of obstruction)
• None/ Partial / Total Collapse
• Supine vs Lateral Position
• DISE permits certain maneuvers, ranging from
manual closure of the mouth only to the Esmarch
maneuver (Mandibular advancement).
• Open-mouth breathing is associated with
reduction of the retro palatal and retroglossal
areas, thus can worsen OSA.

16. DISE VIDEO

18. GUIDELINES
• DISE is not a perfect representation of natural
sleep. Nevertheless, light sedation with relatively
low doses of propofol using target-controlled
infusion did not produce marked changes in the
apnea-hypopnea index or oxygen saturations,
compared with natural sleep.
• However resulting blood concentration, injected
dose, and examination time are important
factors, contributing to over-identification or, on
the contrary, to certain sites being overlooked.

19. GUIDELINES
• It is difficult to determine the individual target
concentration for each patient. Total dose and
examination time thus seem to be critical; there
are at present no stringent guidelines as to when
the examination can be said to be completed.
• During overnight natural sleep study, the range of
BIS values within which apnea occurs could be
determined for the individual patient and applied
as a reference for DISE.

20. Risk & Disadvantages
• No catastrophic events have been reported with DISE. Endotracheal
intubation is extremely rare, and cricothyrotomy and tracheostomy
also have not been reported.
• Over sedation that may lead to airway compromise or central
apnea can be prevented by titrating the sedative agent to the
lowest level that maintains the target of sedation.
• Supplemental oxygen or concurrent positive airway pressure
administration may be an option to prevent complications in high-
risk patients, such as those with morbid obesity or greater medical
co morbidity.
• Other DISE risks include local pain on intravenous infusion of
propofol and allergic reaction to medications.

21. Validity & Reliability
• Inter rater reliability reflects the degree to which
ratings from different reviewers are similar.
• Inter rater reliability was moderate to substantial
(kappa cofficient) in one study of 2 experienced
reviewers, and another study showed greater inter
rater reliability for experienced versus non experienced
reviewers.
 Kezirian EJ, White DP, Malhotra A, et al. Interrater reliability of drug-induced sleep
endoscopy. Arch Otolaryngol Head Neck Surg 2010;136:393–7.
 Vroegop AV, Vanderveken OM, Wouters K, et al. Observer variation in druginduced
sleep endoscopy: experienced versus nonexperienced ear, nose, and throat
surgeons. Sleep 2013;36:947–53.

22. Validity & Reliability
• Test-retest reliability evaluates the ratings on
distinct DISE examinations performed on the
same patient.
• Test-retest reliability also has been shown to
be moderate to substantial.
 Rodriguez-Bruno K, Goldberg AN, McCulloch CE, et al. Test-retest reliability of drug-
induced sleep endoscopy. Otolaryngol Head Neck Surg 2009;140:646–51

23. Conclusion
• DISE can serve as an easy & safe tool to guideline the
surgical procedure. Conversely, it is wise not be
overoptimistic: treating all sites found on DISE is not a
guarantee of success.
• Concentric obstruction, for example, does not seem to
respond well to current surgical techniques.
• Numerous further prospective studies are therefore
indispensable to assess these points and standardize the
DISE technique. Nevertheless, it seems very clear that
developing this tool will undoubtedly enhance sleep
specialists’ understanding of apnea.

24. THANK YOU