The global and evident need to increase the validity and uniformity when performing drug-induced sleep endoscopy

Effect of back-up head-elevated position during drug-induced sleep endoscopy in obstructive sleep apnea patients

PURPOSE

This study aimed to evaluate the difference of upper airway collapse between the back-up head-elevated position (a 45° upward inclination) and supine position to better elucidate the role of back-up head-elevated position in reductions of obstructive sleep apnea (OSA) severity.

METHODS

From August 2016 to May 2019, 198 patients aged between 18 and 70 years were recruited in this study prospectively. Drug-induced sleep endoscopy (DISE) findings were recorded with the patients first placed in the supine position then into the back-up head-elevated position with a 45° upward inclination.

RESULTS

From the supine to back-up head-elevated position, a significant decrease in the severity of collapse was observed in velum anteroposterior collapse and velum concentric collapse (p < 0.001 and p < 0.001, respectively), which was more predominant in patients with mild OSA than in patients with moderate to severe OSA. On the other hand, there was no significant improvement of any other collapse at the level of oropharynx, tongue base, or epiglottis when the position was shifted from the supine into back-up head-elevated position.

CONCLUSIONS

The back-up head-elevated position with a 45° upward inclination improved upper airway obstruction during DISE in velum anteroposterior collapse and velum concentric collapse. The proportion of patients with amelioration of upper airway collapse was much higher in patients with mild OSA than in patients with moderate to severe OSA. The back-up head-elevated position may be a reasonable alternative to traditional positional therapy for certain subgroups of patients with OSA.

Airflow limitation in a collapsible model of the human pharynx: physical mechanisms studied with fluid-structure interaction simulations and experiments

The classical Starling Resistor model has been the paradigm of airway collapse in obstructive sleep apnea (OSA) for the last 30 years. Its theoretical framework is grounded on the wave-speed flow limitation (WSFL) theory. Recent observations of negative effort dependence in OSA patients violate the predictions of the WSFL theory. Fluid-structure interaction (FSI) simulations are emerging as a technique to quantify how the biomechanical properties of the upper airway determine the shape of the pressure-flow curve. This study aimed to test two predictions of the WSFL theory, namely (1) the pressure profile upstream from the choke point becomes independent of downstream pressure during flow limitation and (2) the maximum flowrate in a collapsible tube is V I max = A 3 / 2 ( ρ d A / d P ) - 1 / 2 , where ρ is air density and A and P are the cross-sectional area and pressure at the choke point respectively. FSI simulations were performed in a model of the human upper airway with a collapsible pharynx whose wall thickness varied from 2 to 8 mm and modulus of elasticity ranged from 2 to 30 kPa. Experimental measurements in an airway replica with a silicone pharynx validated the numerical methods. Good agreement was found between our FSI simulations and the WSFL theory. Other key findings include: (1) the pressure-flow curve is independent of breathing effort (downstream pressure vs. time profile); (2) the shape of the pressure-flow curve reflects the airway biomechanical properties, so that V I max is a surrogate measure of pharyngeal compliance.

The use of drug-induced sleep endoscopy in England and Belgium

Purpose

The purpose of this international survey is to ascertain the current practice of drug-induced sleep endoscopy (DISE) for patients with sleep-disordered breathing (SDB) by Otolaryngologists in the United Kingdom and Belgium. We compare the results with recommendations from the European Position Paper on drug-induced sleep endoscopy.

Methods

An online questionnaire was circulated to Consultant Otolaryngologists, independent practitioners, and trainees across the two countries. Eleven questions were used in total.

Results

181 responses from the UK and 117 responses from Belgium were received, mostly from consultants and independent practitioners. SDB was a common presentation to ENT practice, seen by over 90% of clinicians. The use of DISE varied greatly between the two countries (72.9% Belgium, 26.1% UK). 54.1% of Belgian respondents use DISE on over 50% of their patients, compared to only 32.4% of British clinicians. Attitudes of surgeons towards the diagnostic value of DISE varied; in Belgium, the majority (54%) gave a rating of 3 or more (1 = useless to 5 = essential), with no respondents giving a score of 0 (useless). In the UK only 16% of respondents felt DISE had useful clinical value, with 25 respondents deeming it ’useless’. The majority opt for DISE when non-surgical therapies fail (51.4% UK, 61.3% Belgium). The majority of participants do not use objective measures for depth of sedation (75.7% UK, 66.7% Belgium), with a marked variation on anaesthetic methods. 62.2% of UK clinicians do not use a classification system, whereas in Belgium the majority of clinicians (60.8%) use the VOTE grading system.

Conclusions

Clinicians in Belgium were more favourable to using DISE than in the UK. Differences in its clinical effectiveness were apparent between the two countries. A consensus on patient selection, method of sedation and an effective classification system seemed to be lacking from both countries. Further education is required to raise awareness for the use of DISE.

Drug induced sleep endoscopy: its role in evaluation of the upper airway obstruction and patient selection for surgical and non-surgical treatment

Sleep related breathing disorders cause obstruction of the upper airway which can be alleviated by continuous positive airway pressure (CPAP) therapy, oral devices or surgical intervention. Non-surgical treatment modalities are not always accepted by patients and in order to attain successful surgical outcomes, evaluation of the upper airway is necessary to carefully select the patients who would benefit from surgery. There are numerous techniques available to assess the upper airway obstruction and these include imaging, acoustic analysis, pressure transducer recording and endoscopic evaluation. It is essential to note that the nocturnal obstructive upper airway has limited muscle control compared to the tone of the upper airway lumen during wakefulness. Thus, if one were to attempt to identify the anatomical segments contributing to upper airway obstruction in sleep related breathing disorders; it must be borne in mind that evaluation of the airway must be performed if possible when the patient is awake and asleep albeit during drug induced sleep. This fact as such limits the use of imaging techniques for the purpose. Drug induced sleep endoscopy (DISE) was pioneered at Royal National Throat, Nose and Ear Hospital, London in 1990 and initially introduced as sleep nasendoscopy. The nomenclature and the technique has been modified by various Institutions but the core value of this evaluation technique remains similar and extremely useful for identifying the anatomical segment responsible for obstructing the upper airway during sleep in patients with sleep related breathing disorders. There have been numerous controversies that have surrounded this technique but over the last two decades most of these have been addressed and it now remains in the forefront of methods of evaluating the upper airway obstruction. A variety of sedative agents and different grading systems have been described and efforts to unify various aspects of the technique have been made. This article will look at its usefulness and advantages and will discuss some important contributions made to the field of evaluation of the upper airway using DISE.