Safety and efficacy of drug-induced sleep endoscopy using a probability ramp propofol infusion system in patients with severe obstructive sleep apnea

The drug titration paradox: a control engineering perspective

PURPOSE OF REVIEW

The drug titration paradox describes that, from a population standpoint, drug doses appear to have a negative correlation with its clinical effect. This paradox is a relatively modern discovery in anesthetic pharmacology derived from large clinical data sets. This review will interpret the paradox using a control engineering perspective.

RECENT FINDINGS

Drug titration is a challenging endeavor, and the medication delivery systems used in everyday clinical practice, including infusion pumps and vaporizers, typically do not allow for rapid or robust titration of medication being delivered. In addition, clinicians may be reluctant to deviate from a predetermined plan or may be content to manage patients within fixed goal boundaries.

SUMMARY

This drug titration paradox describes the constraints of how the average clinician will dose a patient with an unknown clinical response. While our understanding of the paradox is still in its infancy, it remains unclear how alternative dosing schemes, such as through automation, may exceed the boundaries of the paradox and potentially affect its conclusions.

Association Between Soft Tissue Measures From Computed Tomography and Upper Airway Collapsibility on Drug-Induced Sleep Endoscopy

OBJECTIVE

Positive airway pressure (PAP) titration during drug-induced sleep endoscopy (DISE) provides objective measures of upper airway collapsibility. While skeletal measurements relate to collapsibility measures on DISE, the influence of soft tissue dimensions on upper airway collapsibility is not known. We analyzed the relationship of measures of upper airway soft tissue volumes, specifically soft palate, pharyngeal lateral walls, and tongue, with metrics of collapsibility.

STUDY DESIGN

Cross-sectional analysis from a prospective cohort.

SETTING

Academic medical center.

METHODS

Patients seeking PAP alternative therapies for obstructive sleep apnea (OSA) underwent standardized supine computed tomography (CT) acquisition and DISE protocols. The CT analysis primarily focused on soft tissue volumes and, secondarily, on airway and skeletal volumetric measures. DISE with PAP administration (DISE-PAP) enabled the determination of the pressure at which inspiratory airflow first commenced (pharyngeal critical pressure, PcritA) and the pressure at which inspiratory flow limitation was abolished (pharyngeal opening pressure, PhOP). Both unadjusted and adjusted correlation analyses were performed to understand the relationship between upper airway anatomy and either PcritA or PhOP.

RESULTS

One hundred thirty-nine subjects completed both CT and DISE-PAP. On average, patients were male (70.5%), white (84.2%), middle-aged (56.6 ± 13.5 years), and overweight (29.6 ± 4.7 kg/m2), with moderate-severe apnea-hypopnea index (29.7 ± 21.3 events/h). Adjusted for age, sex, body mass index, and skeletal volumes, soft palate, and lateral pharyngeal wall volumes were not associated with PhOP or PcritA, but a larger tongue was associated with more positive PhOP (⍴ = 0.20, P = .02), and more positive PcritA (⍴ = 0.16, P = .07). Exploratory analyses revealed smaller minimum cross-sectional retropalatal area and intramandibular volume were also associated with increased collapsibility measures.

CONCLUSION

After controlling for clinical factors and skeletal volume, greater tongue volume was associated with more severe collapsibility during DISE. These results, in concert with previous work, suggest that greater tongue volume in a smaller skeletal dimensions contribute to the severity of airway collapsibility, a key driver of OSA pathogenesis.

Physiologic and anatomic determinants of hyoid motion during drug-induced sleep endoscopy

PURPOSE

To examine factors accounting for differences in hyoid motion during obstructive breathing events amongst obstructive sleep apnea (OSA) patients.

METHODS

This was a prospective cohort study from June 2022 to October 2022. Patients with OSA undergoing evaluation for PAP alternative therapies with drug-induced sleep endoscopy with positive airway pressure titration (DISE-PAP). All patients underwent DISE-PAP and concurrent hyoid-focused ultrasound. DISE-PAP enabled measurement of airway physiology (flow, respiratory effort) and airway collapsibility (pharyngeal opening pressure, PhOP). Hyoid-ultrasound enabled hyoid bone movement during obstructive breathing. Respiratory effort was measured using a retro-epiglottic pressure-sensitive catheter. Hyoid position was measured using a standardized, awake, CT protocol. Regression analyses adjusted for age, race, sex, and BMI were performed to associate indices of respiratory effort and CT data with hyoid motion.

RESULTS

On average, the 26 patients in this cohort were older (63.9 ± 10.5 years), male (69%), overweight (29.6 ± 3.99 kg/m2), and with moderate-to-severe OSA (26.8 ± 10.4 events/hour). Greater respiratory effort was associated with increased hyoid motion (β [95% CI] = 0.034 [0.016,0.052], standardized β = 0.261,p = 0.0003). Higher hyoid position was associated with greater hyoid displacement (β [95% CI] = -0.20 [-0.38,-0.01], Standardized β = -0.57, p = 0.036).

CONCLUSION

Our data demonstrate that greater respiratory effort, higher hyoid position, and higher airway collapsibility, but not airflow, are associated with greater hyoid motion during obstructive breathing in DISE. These findings suggest that downward hyoid movement represents a compensatory response to upper airway obstruction. Further studies should investigate the vectors of hyoid motion to better understand its role in sleep-related airway collapse.

Characteristic Pressure Waveforms Can Distinguish Airway Collapse Patterns in Sleep Apnea Patients: A Pilot Study

Objective

To use pharyngeal pressure recordings to distinguish different upper airway collapse patterns in obstructive sleep apnea (OSA) patients, and to assess whether these pressure recordings correlate with candidacy assessment for hypoglossal nerve stimulator (HGNS) implantation.

Study Design

Prospective case series.

Setting

Single tertiary-quaternary care academic center.

Methods

Subjects with OSA prospectively underwent simultaneous drug-induced sleep endoscopy (DISE) and transnasal pharyngeal pressure recording with a pressure-transducing catheter. Pressure was recorded in the nasopharynx and oropharynx, and endoscopic collapse patterns were classified based on site, extent, and direction of collapse. Pressure recordings were classified categorically by waveform shape as well as numerically by inspiratory and expiratory amplitudes and slopes. Waveform shape, amplitude, and slope were then compared with the endoscopic findings.

Results

Twenty-five subjects with OSA were included. Nasopharyngeal waveform shape was associated with the extent of collapse at the level of the palate (P = .001). Oropharyngeal waveform shape was associated with anatomical site of collapse (P < .001) and direction of collapse (P = .019) below the level of the palate. Pressure amplitudes and slopes were also associated with the extent of collapse at various sites. Waveform shape was also associated with favorable collapse pattern on endoscopy for HGNS implantation (P = .043), as well as surgical candidacy for HGNS (P = .004).

Conclusion

Characteristic pharyngeal pressure waveforms are associated with different airway collapse patterns. Pharyngeal pressure is a promising adjunct to DISE in the sleep surgery candidacy evaluation.

The influence of different application patterns of propofol on the sedation courses during drug-induced sleep endoscopy

Objective

The course of sedation during drug-induced sleep endoscopy (DISE) depends on the application pattern of the sedative drug. The depth of sedation should imitate light and deep sleep as well. Moreover, there should be as many breathing cycles as possible available for observation during light and deep sedation. The aim of the study was to evaluate different rates of propofol application with respect to the achieved depth and length of the course of sedation.

Methods

Sixty-three consecutive patients with obstructive sleep apnea and/or snoring undergoing DISE were randomly sedated by propofol perfusion at seven different application patterns: 14, 16, 18, 19, 20, 22 mg/kg/h (0.233, 0.267, 0.3, 0.317, 0.333, 0.367 mg/kg/min) per perfusor and individual bolus application 10 mg each. Sedation depth was monitored by BiSpectral Index™ (BIS). The influence of baseline parameters and the courses of sedation were analyzed.

Results

The application rate was the only factor that influenced the depth of sedation. Basic parameters (gender, age, body mass index, apnea-hypopnea index) had no influence on the depth of sedation. The sedation depth was dependent on the rate of propofol application. Regimes at 14 and 16 mg/kg/h as well as bolus application did not reach BIS levels below 50 representing deep sleep. Propofol doses of more than 20 mg/kg/h led to rapid decreases of sedation levels below deep sleep niveau. Propofol rates between 18 and 20 mg/kg/h enable BIS levels below 50 representing deep sleep and providing enough breathing cycles for observation.

Conclusion

Lower application rates of propofol provide slower courses of sedation and shallower depths of sedation. A rate of 14 mg/kg/h might be appropriate to reach a sedation plateau at light sleep. A rate of 18 mg/kg/h leads to a sedation, corresponding to deep sleep. The combination of both rates might be a suitable pattern for performing sedation-controlled DISE.

Level of evidence

2: Randomized trial.

The Prevalence of Sentinel Central Events (SCent) During Drug-Induced Sleep Endoscopy

OBJECTIVE

With the recent addition of airflow and respiratory effort channels, our group has observed central and mixed apnea events during drug-induced sleep endoscopy (DISE). We measured the frequency and timing of sentinel central and/or mixed events (SCents), as well as assessed for differences in velum, oropharynx, tongue, and epiglottis (VOTE) classification compared to obstructive events.

STUDY DESIGN

Prospective single-cohort study.

SETTING

Tertiary Care Academic Medical Center.

METHODS

Patients underwent DISE between June 2020 and November 2022. Nasal airflow, thoracoabdominal effort belt signals, and videoendoscopy were simultaneously captured. Demographics, sleep study, and DISE data were compared among patients with and without SCents using Student's T tests or χ2 tests.

RESULTS

On average, the cohort (n = 103) was middle-aged (53.5 ± 12.1 years), overweight (body mass index of 29.7 ± 5.3 kg/m2), and had severe obstructive sleep apnea (apnea-hypopnea index of 30.7 ± 18.7 events/h). Forty-seven patients (46%) were found to have at least 1 SCent. Among those with SCent, 45 (95.7%) transitioned to obstructive pathology after an average of 7.91 ± 2.74 minutes, with at least 95% of patients expected to do so within 12.57 minutes. Twenty-nine out of 47 patients (61.2% [95% confidence interval: 46.4.9%, 75.5%]) with SCent had meaningful differences between central/mixed and obstructive VOTE scores.

CONCLUSION

Central events were present in almost half of our cohort. At least 95% of patients were expected to transition to obstructive events within 12 to 13 minutes of propofol initiation. In addition, over half of patients demonstrate significantly different VOTE scores between central and obstructive events. These factors should raise awareness of central events and scoring passive apneas during DISE and consider delaying VOTE scoring.

Airway Collapsibility during Drug-Induced Sleep Endoscopy Relates with Clinical Features of Obstructive Sleep Apnea

INTRODUCTION

Increased pharyngeal collapsibility leads to obstructive sleep apnea (OSA). Positive airway pressure titration during drug-induced sleep endoscopy (DISE-PAP) provides objective collapsibility metrics, the pharyngeal opening pressure (PhOP), and active pharyngeal critical pressure (PcritA ). We examined the interrelationships between risk factors of OSA, airway collapsibility measures, and clinical manifestations of the disease.

METHODS

This is a cross-sectional analysis of consecutive OSA patients undergoing DISE-PAP. Nasal PAP was increased stepwise until inspiratory flow limitation was abolished, signifying PhOP. PcritA was derived from the resulting titration pressure-flow relationships. Clinical data including demographics, anthropometrics, sleep studies, and patient-symptom questionnaires were obtained from the electronic medical record. Multivariate regression was used to evaluate the relationship between risk factors, airway collapsibility, and clinical data.

RESULTS

On average, the 164 patients meeting inclusion criteria were middle-aged (54.2 ± 14.7 years), overweight/obese (BMI 29.9 ± 4.5 kg/m2 ), male (72.6%), White (79.3%) and had severe OSA (AHI 32.0 ± 20.5 events/hour). Mean PhOP was 7.5 ± 3.3 cm H2 O and mean PcritA was 0.80 ± 3.70 cm H2 O. Younger age (Standardized β = -0.191, p = 0.015) and higher BMI (Standardized β = 0.176, p = 0.028) were associated with higher PhOP, but not PcritA . PhOP and PcritA were both associated with AHI, supine AHI, and SpO2 nadir. Higher PhOP was associated with higher snoring scores (Standardized β = 0.246, p = 0.008), but not other patient-reported outcomes.

CONCLUSION

Objective assessment of passive and active airway mechanics during DISE relates with clinical risk factors for OSA. Quantitative measures of collapsibility provide accessible and meaningful data, enhancing the standard sleep surgery evaluation.

LEVEL OF EVIDENCE

4 Laryngoscope, 134:1978-1985, 2024.

The Application of Ultrasound to Quantify Hyoid Motion During Drug-Induced Sleep Endoscopy

INTRODUCTION

The significance of hyoid dynamics in OSA pathophysiology remains unclear. Drug-induced sleep endoscopy (DISE) is often used for evaluating patients intolerant to positive airway pressure (PAP) therapy. We performed DISE with concurrent hyoid-focused ultrasonography to quantify hyoid dynamics during obstructive and non-obstructive breathing.

METHODS

A cross-sectional analysis from a prospective cohort of patients undergoing DISE with PAP titration (DISE-PAP) and hyoid-focused ultrasound was conducted. Hyoid ultrasound was performed during obstructive breathing, and non-obstructive breathing after PAP administration. Motion was quantified by generating displacement curves based on echo-tracking hyoid movement. The image analysis protocol for quantifying hyoid displacement was performed independently by two researchers, and reliability of measures was assessed. Univariate and multivariate regressions were performed for various clinical data and hyoid displacement during obstructive breathing.

RESULTS

Twenty patients met inclusion criteria. On average, the cohort was male (75%), elderly (65.9 ± 10 years), overweight (29.3 ± 3.99 kg/m2 ), and with moderate-to-severe OSA (29.3 ± 12.5 events/h). Mean hyoid displacement during obstructive breathing was 5.81 mm (±3.48). In all patients, hyoid displacement decreased after PAP administration (-3.94 mm [95% CI: -5.10, -2.78]; p < 0.0001). Inter-rater reliability for measures of hyoid displacement was excellent. After multivariate regression, hyoid displacement at baseline was associated with higher AHI (β [95% CI] = 0.18 [0.03, 0.33], p = 0.020).

CONCLUSION

During DISE, hyoid displacement is greater during obstructive breathing with significant variability amongst patients. Further, these ultrasonographic measurements had excellent intra- and inter-rater reliability. Additional, larger studies are needed to understand contributors to hyoid mobility.

LEVEL OF EVIDENCE

4 Laryngoscope, 133:3221-3227, 2023.

Comparison of Remimazolam and Propofol for Drug-Induced Sleep Endoscopy: A Randomized Clinical Trial

OBJECTIVE

To compare the efficacy and safety of remimazolam with those of propofol for drug-induced sleep endoscopy (DISE) in patients with obstructive sleep apnea-hypopnea syndrome (OSAHS).

STUDY DESIGN

A prospective, single-center, randomized clinical trial.

SETTING

Xiangya Hospital of Central South University.

METHODS

Patients with OSAHS receiving DISE were randomly assigned to either the remimazolam or propofol group. The primary outcome was the incidence of hypoxemia (pulse oxygen saturation [SpO2 ] < 90%) during DISE. The secondary outcomes were the incidence of severe hypoxemia (SpO2  < 80%), the minimal value of SpO2 , sedation success rate (completion of DISE according to the medication regimen), and incidence of events of interest (including injection pain, bradycardia, and decreased respiratory rate).

RESULTS

Sixty-four patients were included in this study. The incidence of hypoxemia was significantly lower in the remimazolam than in the propofol group (25.00% vs 62.50%, respectively; relative risk, 0.40; 95% confidence interval [CI], 0.20-0.74; p < .01). There was no significant difference in the sedation success rate between the remimazolam and propofol groups (96.88% vs 81.25%, respectively; relative risk, 1.19; 95% CI, 1.01-1.50; p = .10). The incidence of at least 1 event of interest was lower in the remimazolam than in the propofol group (43.75% vs 96.88%, respectively; relative risk, 0.45; 95% CI, 0.29-0.63; p < .01).

CONCLUSION

Remimazolam can present satisfactory sedative efficacy in DISE, with a lower incidence of hypoxemia and a higher safety profile than propofol.

Efficacy of high-flow nasal oxygen during drug-induced sleep endoscopy in patients with obstructive sleep apnea

PURPOSE

High-flow nasal oxygenation (HFNO) can provide a low level of continuous positive airway pressure and alveolar recruitment. We aimed to compare the efficacy of pre-oxygenation with HFNO and low-flow nasal oxygenation (LFNO) during drug-induced sleep endoscopy (DISE).

METHODS

In the LFNO group, preoxygenation was performed for 10 min at 3 L·min-1. In the HFNO group, preoxygenation was performed for 10 min at 30 L·min-1 at a fraction of inspired oxygen of 100% using the Optiflow device. From the start of sedative administration to the end of DISE, vital signs were monitored continuously. The primary outcome was the lowest oxygen saturation (SpO2) during DISE.

RESULTS

Of 24 patients enrolled, 12 were randomly assigned to the LFNO and 12 to the HFNO groups. The prevalence of hypoxia events was 75% in the LFNO group and 58% in the HFNO group. The difference in lowest oxygen saturation between the two groups was not significant between the two groups (P=0.665). The lowest SpO2 during all procedures was comparable between the two groups (86.8 ± 6.5% in the LFNO group and 87.2 ± 8.0% in the HFNO group; P=0.912).

CONCLUSIONS

The findings suggest that HFNO may not be superior to LFNO as a preoxygenation tool to prevent hypoxia during DISE.

Transverse Maxillary Deficiency Predicts Increased Upper Airway Collapsibility during Drug-Induced Sleep Endoscopy

OBJECTIVE

To examine the relationship between craniofacial skeletal anatomy and objective measures of pharyngeal collapse obtained during drug-induced sleep endoscopy. We hypothesized that transverse maxillary deficiency and an increased pharyngeal length will be associated with higher levels of pharyngeal collapsibility.

STUDY DESIGN

Cross-sectional analysis in a prospective cohort.

SETTING

University Hospital.

METHODS

A cross-sectional analysis was conducted in a cohort of consecutive patients from the positive airway pressure (PAP) alternatives clinic who underwent computed tomography (CT) analysis and drug-induced sleep endoscopy for characterization of upper airway collapsibility. PAP titration was used to determine pharyngeal critical pressure (PCRIT ) and pharyngeal opening pressure (PhOP). CT metrics included: Transverse maxillary dimensions (interpremolar and intermolar distances) and pharyngeal length (posterior nasal spine to hyoid distance).

RESULTS

The cohort (n = 103) of severe obstructive sleep apnea (Apnea and Hipopnea Index 32.1 ± 21.3 events/h) was predominantly male (71.8%), Caucasian (81.6%), middle-aged (54.4 ± 14.3 years), and obese (body mass index [BMI] = 30.0 ± 4.9 kg/m2 ). Reduced transverse maxillary dimensions were associated with higher PCRIT (intermolar distance: β [95% confidence interval, CI] = -.25 [-0.14, -0.36] cmH2 O/mm; p = .03) and PhOP (Interpremolar distance: β = -.25 [-0.14, -0.36] cmH2 O/mm; p = .02). Longer pharyngeal length was also associated with higher PCRIT (β = .11 [0.08, 0.14] cmH2 O/mm, p = .04) and PhOP (β [95% CI] = .06 [0.03, 0.09] cmH2 O/mm, p = .04). These associations persisted after adjustments for sex, age, height, and BMI.

CONCLUSION

Our results further the concept that skeletal restriction in the transverse dimension and hyoid descent are associated with elevations in pharyngeal collapsibility during sleep, suggesting a role of transverse deficiency in the pathogenesis of airway obstruction.

The Accuracy and Reliability of Visually Assessed Pharyngeal Opening Pressures During Drug-Induced Sleep Endoscopy

OBJECTIVE

To examine the accuracy and interrater reliability of a visually assessed vs airflow-based measure of pharyngeal collapsibility obtained in patients with obstructive sleep apnea undergoing drug-induced sleep endoscopy (DISE).

STUDY DESIGN

Prospective observational study.

SETTING

Academic tertiary care practice.

METHODS

Patients underwent DISE with airflow monitoring and nasal positive airway pressure titration to determine visual and airflow-based levels of pharyngeal opening pressure (PhOP). Visual DISE-PhOP was assessed by 2 blinded independent raters and defined as the pressure at which visual confirmation of airway collapse, including snoring, was abolished. Airflow-based DISE-PhOP was defined as the minimally effective positive airway pressure that abolished inspiratory flow limitation. Equivalence testing between visual and airflow DISE-PhOP of each rater was performed with the two one sided T-test (TOST) with an a priori equivalence bound of ±1 cm H2 O. Interrater reliability was evaluated with the intraclass correlation coefficient.

RESULTS

One hundred patients were enrolled in the study and 77 completed the full evaluation. The population was predominantly male (74%) with an average age of 54.8 years, body mass index of 30.1 kg/m2 , and apnea-hypopnea index of 30.7 events/h. Equivalence testing showed that both raters were within ±1 cm H2 O of airflow-based DISE-PhOP (-0.43 to 0.09 cm H2 O and -0.32 to 0.48 cm H2 O). Interrater reliability of visual DISE-PhOP between the raters was also good to excellent with an intraclass correlation coefficient of 0.895 (95% CI, 0.84-0.932).

CONCLUSION

DISE-PhOP, a measure of upper airway collapsibility, was equivalent between airflow-based and visual assessments with strong interrater reliability, supporting its adoption as a standardized objective parameter in clinical DISE.

A Protocol for Propofol-Infusion Drug-Induced Sleep Endoscopy

OBJECTIVE

The objective of this study was to outline a protocol utilizing propofol infusion without an initial bolus during drug-induced sleep endoscopy (DISE). We define normative values for final propofol infusion rate (P^final ) during DISE and sedation depth values at P^final .

STUDY DESIGN

Retrospective chart review.

SETTING

Tertiary academic hospital.

METHODS

A review of patients with obstructive sleep apnea who underwent DISE between 2016 and 2020 was performed. The following patient data were recorded: demographics; DISE procedure details, including P^final , time to P^final , frequency and cadence of infusion rate changes, depth of sedation as measured by Bispectral Index and SedLine values, and hemodynamics; and polysomnography details including apnea-hypopnea index severity and minimum oxygen saturation. A mixed linear model adjusted for age and body mass index was performed for the analysis of effects on P^final . Pearson correlation coefficients determined the strength of association between depth of sedation measured and pattern of collapse on DISE and P^final .

RESULTS

There were 246 patients who met inclusion criteria. P^final resembled a normal distribution (mean ± SD, 156.44 ± 26.69 mcg/kg/min; median, 150 mcg/kg/min). Analysis demonstrated that P^final was influenced by male sex, current smoker status, time to P^final , and number of propofol dose changes (P < .05). Depth of sedation categories measured differently between Bispectral Index and SedLine (55-65 vs 45-55, P < .001). The pattern including severity of collapse on DISE was not associated with P^final (P > .05). No patients required intra- or postoperative respiratory support beyond oxygen via nasal canula.

CONCLUSION

We describe a propofol slow-infusion DISE protocol that demonstrates safe and reproducible outcomes.

Beyond VOTE: The New Frontier of Drug-Induced Sleep Endoscopy

Alternatives to positive airway pressure therapy, including surgery, represent an important area of research. Specifically, predictors of response to surgical therapy remain underdeveloped. Drug-induced sleep endoscopy (DISE) holds promise as a diagnostic tool to identify patient-specific causes of airway collapse. Herein, we present a novel, standardized approach which combines anatomic and physiologic measurements during DISE. Our DISE platform measures airflow, airway compliance, airway collapsibility, and structural drivers of collapse. Taken together, these inputs provide a comprehensive framework to further inform the surgeon in providing personalized care of the patient with obstructive sleep apnea.

Outcomes of Hypoglossal Nerve Upper Airway Stimulation among Patients with Isolated Retropalatal Collapse

Objective

To examine whether patients with isolated retropalatal collapse perform as well as others following implantation with an upper airway stimulation (UAS) device.

Study Design

Retrospective review.

Setting

Single-institution tertiary academic care medical center.

Subjects and Methods

Following drug-induced sleep endoscopy, subjects who met inclusion criteria for implantation with a UAS device received an implant per industry standard. Subjects with isolated retropalatal collapse were compared with those having other patterns of collapse. Outcome measures included apnea-hypopnea index (AHI) and nadir oxyhemoglobin saturation (NOS).

Results

Ninety-one patients were implanted during the duration of the study, and 82 met inclusion criteria for analysis. Twenty-five had isolated retropalatal collapse, while the remaining 57 had other patterns of collapse on drug-induced sleep endoscopy. For all patients, mean preoperative AHI and NOS were 38.7 (95% CI, 35.0-42.4) and 78% (95% CI, 75%-80%), respectively; these improved postoperatively to 4.5 (95% CI, 2.3-6.6) and 91% (95% CI, 91%-92%). There was no significant preoperative difference between groups with regard to demographics, AHI, or NOS. Group comparison showed postoperative AHI to be 5.7 (95% CI, 0.57-10.8) for patients with isolated retropalatal collapse and 3.9 (95% CI, 1.7-6.1) for other patients ( P = .888). Postoperative NOS was 92% (95% CI, 90%-94%) among patients with isolated retropalatal collapse and 91% (95% CI, 90%-92%) for others ( P = .402).

Conclusions

All patients showed significant improvement following implantation with UAS. Patients with isolated retropalatal collapse showed similar improvement to other types of collapse with regard to AHI and NOS.

Drug-induced sleep endoscopy: from obscure technique to diagnostic tool for assessment of obstructive sleep apnea for surgical interventions

PURPOSE OF REVIEW

Provide a practical update on drug-induced sleep endoscopy (DISE) for anesthesia providers, which can also serve as a reference for those preparing to establish a DISE program.

RECENT FINDINGS

New developments in surgical approaches to OSA and the growing global incidence of the condition have stimulated increased interest and demand for drug-induced sleep endoscopy. New techniques include transoral robotic surgery and hypoglossal nerve stimulation. Recent DISE literature has sought to address numerous debates including relevance of DISE findings to those during physiologic sleep and the most appropriate depth and type of sedation for DISE. Propofol and dexmedetomidine have supplanted midazolam as the drugs of choice for DISE. Techniques based on pharmacokinetic models of propofol are superior to empiric dosing with regard to risk of respiratory compromise and the reliability of dexmedetomidine to achieve adequate conditions for a complete DISE exam is questionable.

SUMMARY

The role of DISE in surgical evaluation and planning for treatment of OSA continues to develop. Numerous questions as to the optimal anesthetic approach remain unanswered. Multicenter studies that employ a standardized approach using EEG assessment, pharmacokinetic-pharmacodynamic modelling, and objectively defined clinical endpoints will be helpful. There may be benefit to undertaking DISE studies in non-OSA patients.

Drug-induced sleep endoscopy with target-controlled infusion using propofol and monitored depth of sedation to determine treatment strategies in obstructive sleep apnea

BACKGROUND

Drug-induced sleep endoscopy (DISE) has become an important diagnostic examination tool in the treatment decision process for surgical therapies in the treatment of obstructive sleep apnea (OSA). Currently, there is a variety of regimes for the performance of DISE, which renders comparison and assessment across results difficult. It remains unclear how the different regimes influence the findings of the examination and the resulting conclusions and treatment recommendations. This study aimed to investigate the correlation between increasing levels of sedation (i.e., light, medium, and deep) induced by propofol using a target-controlled infusion (TCI) pump, with the obstruction patterns at the levels of the velum, oropharynx, tongue base, and epiglottis (i.e., VOTE classification). A second goal was the establishment of a sufficient sedation level to enable a reliable decision regarding treatment recommendations.

MATERIAL AND METHODS

Forty-three patients with OSA underwent a DISE procedure using propofol TCI. Three levels of sedation were defined, depending on entropy levels and assessment of sedation: light sedation, medium sedation, and deep sedation. The evaluation of the upper airway at each level, with increasing sedation, was documented using the VOTE classification. The elapsed time at which each assessment was performed was recorded.

RESULTS

Upper airway changes occurred and were measured throughout the DISE procedure. Clinically useful determinations of airway closure occurred at medium sedation; this level of sedation was most probably achieved with a blood propofol concentration of 3.2 μg/ml. In all 43 patients, definite treatment decisions could be made at medium sedation level. Increasing sedation did not result in changes in the treatment decision.

CONCLUSIONS

Changes in upper airway collapse during DISE with propofol TCI occur at levels of medium sedation. Decisions regarding surgical treatment could be made at this level of sedation.

CLINICAL TRIAL NAME

Upper Airway Collapse in Patients with Obstructive Sleep Apnea Syndrome by Drug Induced Sleep Endoscopy (URL: https://clinicaltrials.gov/ct2/results?term=NCT02588300&Search=Search ) REGISTRATION NUMBER: NCT02588300.

Dynamic Drug-Induced Sleep Computed Tomography in Adults With Obstructive Sleep Apnea

Surgical success for obstructive sleep apnea (OSA) depends on identifying sites of obstruction in the upper airway. In this study, we investigated sites of obstruction by evaluating dynamic changes in the upper airway using drug-induced sleep computed tomography (DI-SCT) in patients with OSA. Thirty-five adult patients with OSA were prospectively enrolled. Sleep was induced with propofol under light sedation (bispectral index 70–75), and low-dose 320-detector row CT was performed for 10 seconds over a span of 2–3 respiratory cycles with supporting a continuous positive airway pressure model. Most (89%) of the patients had multi-level obstructions. Total obstruction most commonly occurred in the velum (86%), followed by the tongue (57%), oropharyngeal lateral wall (49%), and epiglottis (26%). There were two types of anterior-posterior obstruction of the soft palate, uvular (94%) and velar (6%), and three types of tongue obstruction, upper (30%), lower (37%), and upper plus lower obstruction (33%). DI-SCT is a fast and safe tool to identify simulated sleep airway obstruction in patients with OSA. It provides data on dynamic airway movement in the sagittal view which can be used to differentiate palate and tongue obstructions, and this can be helpful when planning surgery for patients with OSA.

Value from the Patients' and Payers' Perspectives

Health care costs continue to increase, and the approach of countries and insurers is to focus on the value of the care delivered. Value is a function of quality in relation to costs. The perspective of the individual measuring value is important. Calculation of costs may include return to work if the employer's perspective is taken. The patients' perspectives include out-of-pocket expenses and work lost for both patients and potentially caregivers. The authors provide one example in the area of sleep apnea in which the anesthesiologist can provide value uniquely by being part of the team making the diagnosis.

Comparison of the combination of dexmedetomidine and ketamine to propofol or propofol/sevoflurane for drug-induced sleep endoscopy in children

AIM

Examination of dynamic airway collapse in patients with obstructive sleep apnea (OSA) during drug-induced sleep endoscopy (DISE) can help identify the anatomic causes of airway obstruction. We hypothesized that a combination of dexmedetomidine and ketamine (Group DK) would result in fewer oxygen desaturations and a higher successful completion rate during DISE in children with OSA when compared to propofol (Group P) or sevoflurane/propofol (Group SP).

METHODS

In this retrospective study, we reviewed the records of 59 children who presented for DISE between October 2013 and March 2015. Data analyzed included demographics, OSA severity, and hemodynamics (heart rate and blood pressure). The primary outcomes were airway desaturation during DISE to <85% and successful completion of DISE; these were compared between the three groups: DK, P, and SP.

RESULTS

Preoperative polysomnography was available for 49 patients. There were significantly more patients with severe OSA in Group P as compared to the other two groups. The mean (±sd) bolus dose for ketamine, dexmedetomidine, and propofol were 2.0 ± 0.6 mg·kg(-1) , 1.9 ± 0.9 mcg·kg(-1) , and 1.8 ± 1.1 mg·kg(-1) , respectively. The mean (±sd) infusion rate for dexmedetomidine was 1.6 ± 0.7 mcg·kg(-1) ·h(-1) and for propofol was 248 ± 68 mcg·kg(-1) ·min(-1) in Group P and 192 ± 48 mcg·kg(-1) ·min(-1) in Group SP. Patients in Group DK had significantly fewer desaturations to <85% during DISE compared to Group P. Patients in Group DK had significantly more successful completion of DISE (100% Group DK, 92% Group P, and 79% Group SP) as compared to Group SP.

CONCLUSIONS

These results suggest that the described dose regimen of propofol used alone or in combination with sevoflurane appears to be associated with more oxygen desaturations and a lower rate of successful completion than a combination of dexmedetomidine and ketamine during DISE in children with OSA.

Variable Findings for Drug-Induced Sleep Endoscopy in Obstructive Sleep Apnea with Propofol versus Dexmedetomidine

OBJECTIVE

To compare VOTE classification findings (velum, oropharyngeal-lateral walls, tongue base, and epiglottis) for drug-induced sleep endoscopy (DISE) among patients with obstructive sleep apnea (OSA) using 2 sedation protocols.

STUDY DESIGN

Case series with chart review.

SETTING

Single tertiary institution.

SUBJECTS

Patients with OSA who underwent DISE.

METHODS

A total of 216 patients underwent DISE between November 23, 2011, and May 1, 2015. DISE findings based on VOTE classification were compared between patients receiving the propofol- and dexmedetomidine-based sedation protocols.

RESULTS

Patients with OSA (N = 216; age, 44.3 ± 11.7 years; body mass index, 27.9 ± 4.8 kg/m(2)) underwent DISE with intravenous administration of propofol (n = 52) or dexmedetomidine (n = 164). There were no statistically significant differences between the 2 groups in baseline apnea-hypopnea index, oxygen desaturation index, Mallampati score, tonsil size, Epworth Sleepiness Scale score, peripheral oxygen saturation nadir, age, sex, or body mass index. Patients in the propofol group had a significantly increased likelihood of demonstrating complete tongue base obstruction (75%, 39 of 52) versus partial or no obstruction (25%, 13 of 52) in the anterior-posterior dimension, as compared with the dexmedetomidine group (complete obstruction: 42.7%, 70 of 164; partial or no obstruction: 57.3%, 94 of 164; odds ratio: 4.0; 95% confidence interval: 2.0-8.1; P = .0001). Obstruction of other airway subsites was not significantly different.

CONCLUSION

Use of propofol versus dexmedetomidine to induce sedation may have a significant effect on the pattern of upper airway obstruction observed during DISE. Randomized prospective studies are indicated to confirm these initial findings.

A comparison of dexmedetomidine versus propofol during drug-induced sleep endoscopy in sleep apnea patients

OBJECTIVES/HYPOTHESIS

In this study, we compared the effects of propofol and dexmedetomidine on the upper airway collapse pattern and cardiopulmonary parameters of patients with obstructive sleep apnea (OSA) undergoing drug-induced sleep endoscopy (DISE).

STUDY DESIGN

Prospective, single center, observational study

MATERIALS AND METHODS

The 50 patients with OSA underwent 30 minutes of DISE on 2 different days, the first time with propofol target-controlled infusion (TCI) and the second time with dexmedetomidine TCI. Both the characteristics of upper airway obstruction and cardiopulmonary parameters in response to the depth of sedation achieved with each drug were evaluated.

RESULTS

The results obtained with propofol and dexmedetomidine DISE were in excellent agreement for all sites of obstruction irrespective of the depth of sedation. Although partial or total obstruction at all areas was consistently observed using both drugs, the degree of upper airway narrowing was slightly lower with dexmedetomidine than with propofol. However, the percentage of patients with a greater than 20% change in blood pressure and heart rate compared to baseline was significantly higher in response to propofol than to dexmedetomidine (P = 0.003 and P < 0.001, respectively). Minimal oxygen saturation was significantly lower in DISE with propofol than with dexmedetomidine (P = 0.004). The percentage of patients with oxygen saturation less than 90% or 80% during DISE was significantly higher in response to propofol than to dexmedetomidine (P = 0.032 and P < 0.001, respectively).

CONCLUSION

The DISE findings achieved with propofol and dexmedetomidine were in excellent agreement. However, during DISE, dexmedetomidine provided greater hemodynamic stability and less respiratory depression than propofol.

LEVEL OF EVIDENCE

4. Laryngoscope, 126:763-767, 2016.