Home Sleep Testing versus Traditional Polysomnography: Pros and Cons

Obstructive sleep apnea (OSA) is associated with long-term cardiovascular and respiratory comorbidities and increased burden on the health-care system. Early and accurate diagnosis is essential to reduce physical and financial implications of the disease. Polysomnography uses neurophysiologic channels as well as basic respiratory and sleep parameters to best estimate the presence and/or severity of OSA. Although home sleep testing may have the potential for more variable results, it is a viable alternative to increase access to diagnosis of OSA and facilitate initiation of positive airway pressure.

The Effect of Surgical Therapy for Obstructive Sleep Apnea on Blood Pressure and Peripheral Arterial Tonometry

OBJECTIVE

To determine the effect of upper airway surgery on cardiovascular function in patients with obstructive sleep apnea (OSA).

STUDY DESIGN

A prospective, self-controlled study from 2018 to 2023.

SETTING

Two academic medical centers.

METHODS

Seventy-four patients underwent surgery for OSA, including: tonsillectomy, adenoidectomy, epiglottidectomy, modified uvulopalatopharyngoplasty, maxillary expansion, and maxillomandibular advancement. Twenty-four-hour ambulatory blood pressure (BP), peripheral arterial tonometry (PAT)-based home sleep study, and sleep-related patient-reported outcomes (PROs) were captured preoperatively and at 6 months postoperatively. Paired T-tests evaluated changes in outcomes after surgery.

RESULTS

Forty-one patients successfully completed preoperative and postoperative assessments. Patients were generally middle-aged (43.8 ± 12.5 years), obese (BMI 33.0 ± 5.8 kg/m2), male (68%), White (71%), and had severe OSA (apnea-hypopnea index [AHI] 33.9 ± 29.5 events/h). The 4% oxygen desaturation index (ODI) decreased from 30.7 ± 27.1 to 12.2 ± 13.6 events/h (P < .01) after surgery. There was no significant difference in 24-h BP following surgery, though clinically meaningful reductions in nocturnal systolic (-1.95 [-5.34, 1.45] mmHg) and nocturnal diastolic (-2.30 [-5.11, 0.52] mmHg) blood pressure were observed. Stratified analysis showed patients undergoing skeletal surgery (n = 17) demonstrated larger average reductions compared to those undergoing soft tissue surgery in nocturnal systolic (-4.12 [-7.72, -0.51] vs -0.10 [-5.78, 5.58] mmHg) and nocturnal diastolic (-3.94 [-7.90, 0.01] vs -0.90 [-5.11, 3.31] mmHg) pressures. No meaningful changes were observed in PAT Autonomic Index (PAI) measurements.

CONCLUSION

Surgical therapy for OSA did not demonstrate statistically significant improvements in 24-h BP. However, clinically meaningful reductions in nocturnal BP were observed, particularly in skeletal surgery patients, supporting the need for larger studies of cardiovascular outcomes following OSA surgery.

Hypoglossal Nerve Stimulation and Cardiovascular Outcomes for Patients With Obstructive Sleep Apnea: A Randomized Clinical Trial

Importance

Sham-controlled trials are needed to characterize the effect of hypoglossal nerve stimulation (HGNS) therapy on cardiovascular end points in patients with moderate-severe obstructive sleep apnea (OSA).

Objective

To determine the effect of therapeutic levels of HGNS, compared to sham levels, on blood pressure, sympathetic activity, and vascular function.

Design, Setting, and Participants

This double-blind, sham-controlled, randomized crossover therapy trial was conducted from 2018 to 2022 at 3 separate academic medical centers. Adult patients with OSA who already had an HGNS device implanted and were adherent and clinically optimized to HGNS therapy were included. Participants who had fallen asleep while driving within 1 year prior to HGNS implantation were excluded from the trial. Data analysis was performed from January to September 2022.

Interventions

Participants underwent a 4-week period of active HGNS therapy and a 4-week period of sham HGNS therapy in a randomized order. Each 4-week period concluded with collection of 24-hour ambulatory blood pressure monitoring (ABPM), pre-ejection period (PEP), and flow-mediated dilation (FMD) values.

Main Outcomes and Measures

The change in mean 24-hour systolic blood pressure was the primary outcome, with other ABPM end points exploratory, and PEP and FMD were cosecondary end points.

Results

Participants (n = 60) were older (mean [SD] age, 67.3 [9.9] years), overweight (mean [SD] body mass index, calculated as weight in kilograms divided by height in meters squared, 28.7 [4.6]), predominantly male (38 [63%]), and had severe OSA at baseline (mean [SD] apnea-hypopnea index, 33.1 [14.9] events/h). There were no differences observed between active and sham therapy in 24-hour systolic blood pressure (mean change on active therapy, -0.18 [95% CI, -2.21 to 1.84] mm Hg), PEP (mean change on active therapy, 0.11 [95% CI, -5.43 to 5.66] milliseconds), or FMD (mean change on active therapy, -0.17% [95% CI, -1.88% to 1.54%]). Larger differences between active and sham therapy were observed in a per-protocol analysis set (n = 20) defined as experiencing at least a 50% reduction in apnea-hypopnea index between sham and active treatment.

Conclusions and Relevance

In this sham-controlled HGNS randomized clinical trial, mean 24-hour systolic blood pressure and other cardiovascular measures were not significantly different between sham and active HGNS therapy. Several methodologic lessons can be gleaned to inform future HGNS randomized clinical trials.

Trial Registration

ClinicalTrials.gov Identifier: NCT03359096.

Enhanced drug-induced sleep endoscopy: Distinguishing central from obstructive apnea

This case report describes a patient originally diagnosed with obstructive sleep apnea (OSA) who was later found to have central sleep apnea (CSA) during drug-induced sleep endoscopy, which was subsequently confirmed on an in-laboratory sleep study. The revised diagnosis resulted in a change in recommended therapy from hypoglossal nerve stimulation to phrenic nerve stimulation. This case report is a reminder that the sleep surgeon must be cognizant of the possibility of CSA being misclassified as OSA especially as home sleep studies become increasingly routine, and discusses ways to more easily distinguish between CSA and OSA. Laryngoscope, 133:706-708, 2023.

Financial impact of the COVID-19 pandemic on an academic otolaryngology department

Objective

To quantify the financial impact of the coronavirus disease (COVID-19) pandemic on an academic otolaryngology department.

Methods

A year-over-year comparison was used to compare department revenue from April 2020 and April 2021 as a percentage of baseline April 2019 activity.

Results

At the onset of the COVID-19 pandemic in April 2020, total department charges decreased by 83.4%, of which outpatient clinic charges were affected to the greatest extent. One year into pandemic recovery, department charges remained down 6.7% from baseline, and outpatient clinic charges remained down 9.9%. The reduction in outpatient clinic charges was mostly driven by a decrease in in-office procedure charges.

Conclusion

Given that precautions to mitigate the risk of viral transmission in the health care setting are likely to be long-lived, it is important to consider the vulnerabilities of our specialty to mitigate financial losses going forward.

Sialendoscopy for sialodocholithiasis following submandibular gland excision: six variations on a theme

Sialendoscopy is a minimally invasive technique that facilitates the diagnosis and treatment of sialolithiasis. This case series presents the novel use of sialendoscopy to treat sialodocholithiasis in six patients with a non-functional or surgically absent submandibular gland by a single surgeon at the University of Pennsylvania Health System between March 2013 and December 2019. The four female and two male patients had a median age of 56 years and mean follow-up of 16.2 months (range 1-44.5). All stones were successfully removed using sialendoscopy, and in 5 patients a combined approach was utilized. All patients remain asymptomatic at last clinical follow-up. We conclude that sialendoscopy is a viable, minimally invasive method for managing sialodocholithiasis in patients with prior submandibular gland excision or atretic gland. It is also useful as an assistive tool when approaching complex transcervical or transoral procedures in previously instrumented patients.

Effect of Electrode Configuration and Impulse Strength on Airway Patency in Neurostimulation for Obstructive Sleep Apnea

OBJECTIVES/HYPOTHESIS

Hypoglossal nerve stimulation (HNS) has gained increasing interest for the treatment of patients with obstructive sleep apnea (OSA). Drug-induced sleep endoscopy (DISE) can both exclude improper airway collapse patterns and visualize airway changes under stimulation. Stimulation outcome effects depend on the impulse voltage and electric field resulting from the electrode configuration of the implanted device. The effects of various combinations of voltage and electric field on DISE airway patterns in contrast to awake endoscopy are unknown.

STUDY DESIGN

Cohort study.

METHODS

During therapy adjustment about 6 months after implantation, patients underwent a DISE and awake endoscopy with 100% and 125% of functional voltage in three typical electrode configurations (+ - +, o - o, - - -). All videos were analyzed by two separate persons for the opening of the airway at velum, tongue base, and epiglottis level.

RESULTS

Thirty patients showed typical demographic data. The opening effects were visible in all patients, but there were changes between different electrode configurations. Several demographic or therapeutic aspects such as obesity, OSA severity, or prior soft palate surgery were associated with changes arising from different electrode configurations, but none resulted in a consistently better airway opening.

CONCLUSIONS

In patients with poor results during the therapy adjustment, electric configuration changes can improve airway patency-an independent variable from increasing voltage. As these effects can only be seen in awake endoscopy or DISE, both endoscopies with live stimulation may be considered in cases with insufficient improvement in apnea-hypopnea index after initiation of HNS therapy.

LEVEL OF EVIDENCE

Prospective case series; level 4. Laryngoscope, 131:2148-2153, 2021.

History and Acceptance of Transoral Robotic Surgery

The development and acceptance of transoral robotic surgery from an experimental procedure to widespread acceptance in the management of head and neck cancers and other disease states occurred over the course of about a decade, from 2005 to 2015. Transoral robotic surgery has cemented its' place in the treatment of pharyngeal and laryngeal cancer. Education and training was key to broad use and acceptance. This article traces the history and evolution of transoral robotic surgery to its current practice. The process of surgical innovation in this arena is followed from early cadaveric studies to recent large systemic reviews of outcomes.

Snapshot Impact of COVID-19 on Mental Wellness in Nonphysician Otolaryngology Health Care Workers: A National Study

Objective

Nonphysician health care workers are involved in high-risk patient care during the COVID-19 pandemic, placing them at high risk of mental health burden. The mental health impact of COVID-19 in this crucial population has not been studied thus far. Thus, the objective of this study is to assess the psychosocial well-being of these providers.

Study Design

National cross-sectional online survey (no control group).

Setting

Academic otolaryngology programs in the United States.

Subjects and Methods

We distributed a survey to nonphysician health care workers in otolaryngology departments across the United States. The survey incorporated a variety of validated mental health assessment tools to measure participant burnout (Mini-Z assessment), anxiety (Generalized Anxiety Disorder-7), distress (Impact of Event Scale), and depression (Patient Health Questionnaire-2). Multivariable logistic regression analysis was performed to determine predictive factors associated with these mental health outcomes.

Results

We received 347 survey responses: 248 (71.5%) nurses, 63 (18.2%) administrative staff, and 36 (10.4%) advanced practice providers. A total of 104 (30.0%) respondents reported symptoms of burnout; 241 (69.5%), symptoms of anxiety; 292 (84.1%), symptoms of at least mild distress; and 79 (22.8%), symptoms of depression. Upon further analysis, development of these symptoms was associated with factors such as occupation, practice setting, and case load.

Conclusion

Frontline otolaryngology health care providers exhibit high rates of mental health complications, particularly anxiety and distress, in the wake of COVID-19. Adequate support systems must be put into place to address these issues.

Prospective Determination of Airway Response to Upper Airway Stimulation: A New Opportunity for Advanced Device Titration

OBJECTIVES/HYPOTHESIS

Response to upper airway stimulation (UAS) is associated with the degree of airway opening during stimulation. UAS programming may affect this opening. The objective of this study was to examine airway changes in response to five different electrode configurations programmable within the Inspire UAS system.

STUDY DESIGN

Prospective single-arm cohort study.

METHODS

Subjects who underwent UAS implantation were recruited for a prospective single-arm cohort study during UAS device activation. Functional thresholds were recorded for all settings. Awake nasopharyngoscopy was performed to examine the retropalatal (RP) and retroglossal (RG) regions at rest and during activation with all settings at their functional thresholds. Cross-sectional measurements were made by two blinded reviewers and reported as percent change in airway size.

RESULTS

Sixteen patients were included. The standard setting (+-+) resulted in the greatest change in RP area in 43.8% of patients. An alternative setting resulted in greatest change in 56.2% of patients (--- and o-o in 18.8% each, -o- in 12.5%, and -+- in 6.3% of patients). Average response to all five settings was utilized to classify degree of palatoglossal coupling. Most patients had some enlargement (20%-70% change in RP area, 43.8%) or no enlargement (<20% change, 43.8%), whereas a minority of patients (12.5%) had marked enlargement (>70% change). RP and RG expansion were not correlated.

CONCLUSION

Degree of RP expansion varied among patients and settings. Although the standard setting resulted in greatest RP change in a plurality of patients, over half had a greater response to an alternative setting. Future studies should address whether choice of setting based on RP expansion results in improved outcomes.

LEVEL OF EVIDENCE

4 Laryngoscope, 131:218-223, 2021.

Base of Tongue Surgery for Obstructive Sleep Apnea in the Era of Neurostimulation

Retroglossal collapse is commonly seen in patients with obstructive sleep apnea. The role of upper airway stimulation surgery for these patients continues to evolve. However, base of tongue reduction surgery continues to have usefulness for appropriately selected patients with obstructive sleep apnea. Specific tongue base approaches may vary in response to patient and surgeon preferences and be used in multilevel surgery where appropriate. Key factors include patient age, willingness to undergo device implantation, and preferences for outpatient versus inpatient procedure, single procedure versus multiple, and tolerance for various procedure-specific postoperative restrictions and potential complications.

Factors Predicting Endoscopic Exposure of Zenker's Diverticulum

Objectives

The objectives of this study were 1) to understand which anatomic variables are associated with failed endoscopic exposure of Zenker's diverticulum and 2) to enable preoperative selection of patients suitable for endoscopic repair of Zenker's diverticulum on the basis of anatomic variables.

Methods

We performed a prospective, Institutional Review Board-approved study of 30 patients undergoing attempted endoscopic repair of Zenker's diverticulum. Three categorical variables (sex, presence of maxillary dentition, and Mallampati score) and 6 continuous variables (age, neck circumference, hyomental distance, neck length, neck extension, and body mass index [BMI]) were collected before operation and then correlated to successful endoscopic exposure of the Zenker's pouch by use of a Fisher's exact test and Student's t-test, respectively.

Results

Exposure was unsuccessful in 9 of 30 patients (30%). Factors that correlated significantly with exposure failure included a shorter neck length (7.2 ± 1.2 cm; p = 0.047), a shorter hyomental distance (5.0 ± 1.1 cm; p = 0.004), and a higher BMI (27.2 ±4.0 kg/m2; p = 0.05). The presence of maxillary dentition did not reach significance in exposure failure, but did show a trend toward an association.

Conclusions

Surgical exposure in endoscopic repair of Zenker's diverticulum tends to be significantly less successful in patients with short necks, decreased hyomental distance, and/or a high BMI. An open approach should be considered in this patient population.

Upper airway stimulation therapy and sleep architecture in patients with obstructive sleep apnea

OBJECTIVES/HYPOTHESIS

To quantify changes in sleep architecture before and after upper airway stimulation (UAS) therapy in patients with obstructive sleep apnea.

STUDY DESIGN

Retrospective chart review.

METHODS

This study was performed at a single-institution tertiary academic care center. Patients who responded successfully to UAS implantation were selected for this study. Preoperative and postoperative sleep studies were compared to determine sleep architecture changes. Primary outcomes included sleep architecture parameters such as N1, N2, N3, and rapid eye movement (REM) in addition to others. Secondary outcomes included body mass index.

RESULTS

Thirty-five patients met inclusion criteria for this study. There was significant improvement across several sleep architecture parameters. N1 sleep percent decreased from 16.7% ± 2.1% preoperatively to 10.1% ± 1.6% postoperatively (P = .023). Time spent in N2 increased from 148.0 ± 12.4 minutes to 185.5 ± 10.4 minutes (P = .030), whereas N3 increased from 21.9 ± 5.0 minutes to 57.0 ± 11.1 minutes (P = .013). No significant changes were observed in REM sleep. Arousal index decreased from 38.8 ± 4.0 to 30.3 ± 4.0 (P = .050).

CONCLUSIONS

There was significant improvement across several sleep architecture parameters among patients who responded successfully to UAS implantation.

LEVEL OF EVIDENCE

4 Laryngoscope, 130:1085-1089, 2020.

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 and Surgical Outcomes: A Multicenter Cohort Study

OBJECTIVE

To evaluate the association between findings of blinded reviews of preoperative drug-induced sleep endoscopy (DISE) examinations using the VOTE Classification and obstructive sleep apnea (OSA) surgical outcomes in a large multicenter, international cohort.

METHODS

Retrospective, multi-center cohort study of adults without tonsillar hypertrophy who underwent pharyngeal surgery for OSA. The study included only participants without enlarged tonsils. Four independent reviewers performed blinded review of preoperative DISE videos using the VOTE Classification system and scoring of a primary structure contributing to airway obstruction. DISE findings were examined for an association with surgical outcomes with univariate analyses and multiple regression.

RESULTS

Two hundred seventy-five study participants were included from 14 centers. Mean age was 51.4 ± 11.8 years, and body mass index was 30.1 ± 5.2 kg/m² . There was moderate interrater reliability (kappa = 0.40-0.60) for DISE findings. Oropharyngeal lateral wall-related obstruction was associated with poorer surgical outcomes (adjusted odds ratio (AOR) 0.51; 95% CI 0.27, 0.93). Complete tongue-related obstruction was associated with a lower odds of surgical response in moderate to severe OSA (AOR 0.52; 95% CI 0.28, 0.98), with findings that were similar but not statistically significant in other analyses. Surgical outcomes were not clearly associated with the degree and configuration of velum-related obstruction or the degree of epiglottis-related obstruction. Surgical response was associated with tonsil size and body mass index (inversely).

CONCLUSION

DISE findings concerning the oropharyngeal lateral walls and tongue may be the most important findings of this evaluation technique.

LEVEL OF EVIDENCE

2B Laryngoscope, 129:761-770, 2019.

Transoral robotic surgery versus upper airway stimulation in select obstructive sleep apnea patients

OBJECTIVES

Transoral robotic surgery (TORS) has been used to treat obstructive sleep apnea (OSA) since 2009, with recent meta-analysis showing an average reduction of apnea-hypopnea index (AHI) from 44.3 to 17.0. In 2014, upper airway stimulation surgery (UAS) was approved for OSA treatment, with results showing an average AHI reduction from 32.0 to 15.3. Given there was a period when TORS was available and UAS was not, we looked at a subset of patients treated with TORS but who could have qualified for UAS and compared their outcomes to patients who received UAS.

METHODS

This is a retrospective chart review comparing TORS to UAS in treatment of OSA performed by a single surgeon between 2011 and 2016. Inclusion criteria were a body mass index less than 35 and AHI between 20 and 65 consistent with criteria for UAS implantation. Patients who received TORS and met the inclusion criteria had their preoperative drug-induced sleep endoscopy recordings re-evaluated. Patients with anteroposterior retropalatal collapse that would have qualified them for UAS had their outcomes compared to patients who received UAS.

RESULTS

Results between TORS and UAS showed an average AHI reduction of 12.7 and 33.3, respectively. Overall cure rate, defined as AHI < 5, was 10.0% and 70.3%, respectively.

CONCLUSION

Results of this study indicate that, when met with criteria for both TORS and UAS, patients receiving UAS had greater improvement in several objective measures of OSA. Studies like this may help direct future treatment algorithms for surgical management of OSA.

LEVEL OF EVIDENCE

4 Laryngoscope, 129:256-258, 2019.

Wound odor: current methods of treatment and need for objective measures

Chronic wounds are an enormous burden to society, costing billions of dollars annually in the USA alone. Despite the extensive research into methods to heal chronic wounds, many remain unhealed for months to years. There is a need to focus on patient reported outcomes to improve quality of life in patients with non-healing wounds. Wound odor has a significant impact on patient quality of life; however, relatively little information is available on the management of wound odor. We review the current data available on wound odor and discuss the need for standardized objective measures of odor to improve research quality. An independent search of the PubMed and Embase databases was conducted using combinations of the following words or phrases: "wounds," "chronic wounds," "diabetic ulcers," "venous leg ulcers (VLUs)," "malignant ulcers," "odor," "odour," "smell," "malodor," "artificial olfaction," "electronic nose," and "e-nose." Article references were also searched for significance. There are few overall studies on wound odor, and fewer randomized controlled trials. Current trials on odor have consistent weaknesses such as subjective measures and poor methodology. No single odor treatment modality has been demonstrated to be widely effective for wound odor or superior to other methods. Future research should incorporate objective measures of odor such as electronic noses into clinical trials.

Preoperative Lund-Mackay computed tomography score is associated with preoperative symptom severity and predicts quality-of-life outcome trajectories after sinus surgery

BACKGROUND

Disagreement exists about the relationship between Lund-Mackay CT scores (LMCTS) and quality-of-life outcome (QoL) measures. We investigated whether preoperative LMCTS are associated with preoperative QoL, and whether LMCTS is predictive of postoperative QoL outcomes in chronic rhinosinusitis (CRS) patients.

METHODS

Adult patients with medically recalcitrant CRS (n = 665) were enrolled in a prospective, observational cohort study. Preoperative LMCTS and pre- and postoperative self-reported QoL outcomes (22-item Sino-Nasal Outcomes Test [SNOT-22]) were collected and evaluated over 12 months. Five hundred sixty-eight patients met the inclusion criteria. Longitudinal linear mixed-effects modeling was used to investigate the effect of LMCTS on QoL after functional endoscopic sinus surgery (FESS).

RESULTS

Preoperative LMCTS were significantly associated with preoperative SNOT-22 scores (p < 0.01) and postoperative SNOT-22 scores (p < 0.001), driven by Extranasal and Rhinologic subdomains of the QoL questionaire. Patients in the lowest preoperative LMCTS quartile had the lowest mean change in SNOT-22 scores at 12 months (16.8 points; 95% confidence interval [CI], 12.2-21.3). Patients in the second and third lowest preoperative LMCTS quartiles had mean changes at 12 months of 21.1 points (95% CI, 16.7-25.4) and 23.1 points (95% CI, 18.3-27.9). Patients in the highest preoperative LMCTS quartile had the greatest improvement in SNOT-22 scores after FESS (29.9 points; 95% CI, 24.9-34.8). The difference in QoL change at 12 months between the highest and lowest preoperative LMCTS quartiles was 13.1 points (95% CI, 6.0-20.2; p < 0.001).

CONCLUSION

Our study demonstrates that preoperative LMCTS correlate with preoperative extranasal and rhinologic symptom severity and that the LMCTS is an indicator of postsurgical QoL outcomes for medically recalcitrant chronic rhinosinusitis patients in a large tertiary otolaryngology setting.

Medical Applications of Electronic Nose Technology: Review of Current Status

Electronic noses, or artificial sensors of odorants, have been developed over the last ten years to perform a variety of identification tasks in various industries. This powerful technology is only beginning to be introduced in the field of medicine, but is promising in its potential to assist in diagnosis. This article reviews electronic nose technology and some initial investigations of potential applicability of the technology in the field of medicine.

Use of an Electronic Nose to Diagnose Bacterial Sinusitis

Background

Having previously established that an electronic nose (enose) can distinguish among bacteria samples, between cerebrospinal fluid leak and serum, and can identify patients with ventilator-associated pneumonia, we hypothesized that bacterial sinusitis could be diagnosed by sampling exhaled gas with an enose.

Methods

Using a nasal continuous positive airway pressure mask, we sampled gas exhaled through the nose of patients with sinusitis and compared them with controls. Data were first projected onto the principal components and then classified by support vector machine (SVM), a machine learning algorithm for pattern recognition.

Results

SVM analysis showed good discrimination using three approaches. First, 11 samples were used to create a training set that was used to predict whether individual samples from each set were a member of the control or infected sets. The enose was correct 98.4% of the time. Second, one-half of the samples from each of the same 11 control and infected groups were used to construct a training set, which was used to predict infection in the remaining samples. The enose was correct 82% of the time. Finally, 68 samples (34 positive and 34 controls) were analyzed using a leave-one-out scheme for creating training sets and testing sets. This method, designed to reflect the generalization property of the SVM classifier, scored a classification rate of 72%.

Conclusion

Using the enose to sample nasal exhalation from patients with suspected sinusitis, we were able to predict correctly the diagnosis of sinusitis in at least 72% of the samples. The next step will be to do forward prediction using this model.

Single-institution experience and learning curve with upper airway stimulation

As upper airway stimulation (UAS) surgical implantation is a new procedure, the authors thought it would be instructive to describe a single-institution's experience with the inception of a UAS program. The description of our experience at the University of Pennsylvania may be useful for planning purposes when surgeons and sleep medicine physicians are considering program development. Laryngoscope, 126:S17-S19, 2016 Laryngoscope, 126:S17-S19, 2016.

Volumetric MRI analysis pre- and post-Transoral robotic surgery for obstructive sleep apnea

OBJECTIVES/HYPOTHESIS

To quantitatively measure volumetric changes in upper airway soft tissue structures using magnetic resonance imaging (MRI) pre- and post transoral robotic surgery for obstructive sleep apnea (OSA-TORS).

STUDY DESIGN

Prospective, nonrandomized, institutional board-approved study.

METHODS

Apneics undergoing OSA-TORS, which included bilateral posterior hemiglossectomy with limited pharyngectomy and uvulopalatopharyngoplasty, had upper airway MRIs pre- and postoperatively. Changes (percent and absolute values) in upper airway and surrounding soft tissue volumes were calculated. We assessed whether there were significant volumetric changes and if changes correlated with apnea-hypopnea index (AHI) changes.

RESULTS

Nineteen MRIs and 18 polysomnograms were analyzed pre- and postoperation. Total airway volume increased by 19.4% (P = 0.030). Soft palate and tongue volumes decreased by 18.3% (P = 0.002) and 5.8% (P = 0.013), respectively. Retropalatal and total lateral wall volumes decreased by 49.8% (P = 0.0001) and 17.9% (P = 0.008), respectively. Changes in other structures were not significant. Eleven patients had surgical success, with a mean AHI decrease of 52.9; six were nonsuccesses with a mean AHI decrease of 4.5 (P =0.006). Decreased retropalatal lateral wall volume correlated with decreased AHI.

CONCLUSION

Airway, tongue, soft palate, and lateral wall volumes change significantly after OSA-TORS. Changes in the volume of the lateral walls correlated with changes in AHI. Volumetric upper airway MRI may be a helpful tool to better understand reasons for surgical success.

LEVEL OF EVIDENCE

4.

Ask the Experts: Sleep Surgery Potpourri

Program Description:

Modification of uvulopalatopharyngoplasty (UPPP) as well as variation in treatment of hypopharyngeal obstruction are numerous. Selecting the right technique for the right patient often becomes the most difficult decision in treatment planning. It is often unclear if the proponents of a particular technique apply their “modifications” for every case or if there is a selection process. The purpose of this miniseminar is to present specific cases and hear the opinion of 5 experts on how they would treat the same patient.

Educational Objectives:

(1) Use the appropriate patient selection for a classic UPPP. (2) Determine when uvula preservation techniques are appropriate. (3) Examine the current thinking in tongue base reduction.

Predicting Success of Transoral Robotic Surgery for OSA Using Preoperative Sleep Endoscopy and MRI Analysis

Objectives:

Determine the relationship between surgical success and both preoperative drug-induced sleep endoscopy (DISE) airway caliber changes and volumetric magnetic resonance imaging (MRI) in patients with obstructive sleep apnea (OSA) undergoing transoral robotic assisted posterior glossectomy and uvulopalatopharyngoplasty (OSA-TORS).

Methods:

From 2009 to present, as part of a nonrandomized prospective trial, patients with OSA undergoing OSA-TORS had preoperative DISE and pre- and postoperative volumetric MRI of the upper airway. Quantitative analysis of the endoscopy and MRI were compared with surgical success based upon pre- and postoperative polysomnogram, with success defined as postoperative apnea-hypopnea index (AHI) <20 and AHI decrease ≥50%. Preoperative MRI volumes were also compared against DISE changes.

Results:

Thirty-five apneics undergoing OSA-TORS underwent DISE, 21 received MRIs. DISE data showed that patients with surgical success had a smaller percentage decrease in overall airway collapse in the retroepiglottic ( P = .045) and retroglottic regions ( P = .08) compared with nonsuccesses. Larger preoperative MRI retroglottic airway volumes correlated with increased retroglottic ( P = .05) and retroepiglottic ( P = .03) lateral airway collapse on DISE, however, differences in pre- and postoperative MRI airway volumes did not correlate with surgical success.

Conclusions:

Larger retroglottic airway volume on MRI correlated with greater lateral airway collapse during DISE, but not with surgical success. Successes after OSA-TORS had significantly smaller airway collapse in the retroepiglottic regions than nonsuccesses during DISE, possibly due to better baseline muscle tone, allowing for better ability to benefit from the relatively small change in airway volume that OSA-TORS provides. Preoperative quantitative DISE could be used to identify patients more likely to succeed after OSA-TORS.

Transoral Robot-Assisted Lingual Tonsillectomy and Uvulopalatopharyngoplasty for Obstructive Sleep Apnea

Objectives:

We assessed the use of transoral robot-assisted lingual tonsillectomy and uvulopalatopharyngoplasty for the surgical management of tongue base obstruction in patients with obstructive sleep apnea.

Methods:

In a prospective, nonrandomized trial using historical controls, patients underwent drug-induced sleep endoscopy, transoral robot-assisted lingual tonsillectomy with uvulopalatopharyngoplasty, and preoperative and postoperative polysomnography.

Results:

Twenty patients have completed the study to date. The rate of surgical success was 45%, and the rate of surgical response was 65%. The mean preoperative apnea-hypopnea index of 55.6 decreased by 56.7%, to a mean postoperative value of 24.1 (p < 0.001), and the minimum arterial oxygen saturation increased from the mean preoperative value of 75.8% to the mean postoperative value of 81.7% (p = 0.013). The mean Epworth Sleepiness Scale score improved from 13.4 to 5.9 (p = 0.003). One patient had postoperative bleeding that required cauterization, resulting in a major complication rate of 4.2%.

Conclusions:

Transoral robot-assisted lingual tonsillectomy with uvulopalatopharyngoplasty is a novel technique for the surgical management of obstructive sleep apnea that results in a significant decrease in the apnea-hypopnea index, a significant improvement in minimum arterial oxygen saturation, and a significant improvement in the Epworth Sleepiness Scale score and has an acceptable complication rate.

Factors predicting endoscopic exposure of Zenker's diverticulum

OBJECTIVES

The objectives of this study were 1) to understand which anatomic variables are associated with failed endoscopic exposure of Zenker's diverticulum and 2) to enable preoperative selection of patients suitable for endoscopic repair of Zenker's diverticulum on the basis of anatomic variables.

METHODS

We performed a prospective, Institutional Review Board-approved study of 30 patients undergoing attempted endoscopic repair of Zenker's diverticulum. Three categorical variables (sex, presence of maxillary dentition, and Mallampati score) and 6 continuous variables (age, neck circumference, hyomental distance, neck length, neck extension, and body mass index [BMI]) were collected before operation and then correlated to successful endoscopic exposure of the Zenker's pouch by use of a Fisher's exact test and Student's t-test, respectively.

RESULTS

Exposure was unsuccessful in 9 of 30 patients (30%). Factors that correlated significantly with exposure failure included a shorter neck length (7.2 +/- 1.2 cm; p = 0.047), a shorter hyomental distance (5.0 +/- 1.1 cm; p = 0.004), and a higher BMI (27.2 +/- 4.0 kg/m2; p = 0.05). The presence of maxillary dentition did not reach significance in exposure failure, but did show a trend toward an association.

CONCLUSIONS

Surgical exposure in endoscopic repair of Zenker's diverticulum tends to be significantly less successful in patients with short necks, decreased hyomental distance, and/or a high BMI. An open approach should be considered in this patient population.

The Effects of Serum and Urinary Cortisol Levels of Topical Intranasal Irrigations with Budesonide Added to Saline in Patients with Recurrent Polyposis after Endoscopic Sinus Surgery

Background

The delivery of topical intranasal corticosteroid sprays has traditionally been the primary method of treating recurrent nasal polyposis. An emerging treatment for polyposis is budesonide nasal irrigations. Delivered at concentrations nearly 100 times greater than found in prescription nasal sprays, there have been little studies on the effects of budesonide irrigation on the adrenal axis. Therefore, we investigated whether irrigation with budesonide solution was associated with any increase in serum cortisol and 24-hour urinary cortisol levels.

Methods

Patients who previously had undergone endoscopic sinus surgery and were not taking prednisone for 3 months were prospectively enrolled in this study. Patients irrigated twice daily with 0.5 mg/2 mL of budesonide mixed with 240 mL of saline solution. Serum cortisol and 24-hour urinary cortisol were collected before drug administration and 6 weeks after continuous use.

Results

Ten patients completed this study. The average serum cortisol and 24-hour urinary cortisol before drug administration were 9.8 ± 5.4 μg/dL and 28.1 ± 15.1 μg/24 hours, respectively. After 6-week follow-up, the average serum cortisol and 24-hour urinary cortisol were 12.8 ± 3.5 μg/dL and 16.5 ± 5.6 μg/24 hours, respectively. Normal ranges for serum cortisol and 24-hour urinary cortisol are 5–25 μg/dL and 4–50 μg/24 hours, respectively. Conclusions: Irrigation with budesonide, 0.5 mg/2 mL, in 250 mL of saline solution does not result in decreases of serum cortisol and 24-hour urinary cortisol levels. Based on this, we feel irrigation with budesonide solution is safe to perform in patients as an alternative to traditional aerosolized steroid sprays or systemic corticosteroids.

The role of MR imaging in detecting nodal disease in thyroidectomy patients with rising thyroglobulin levels

BACKGROUND AND PURPOSE

One of the dilemmas facing clinicians treating patients with thyroid cancer is the evaluation of postthyroidectomy patients with rising serum thyroglobulin levels and indeterminate or normal findings on neck sonography. In this study, we examine the role of MR imaging in this subgroup of patients.

MATERIALS AND METHODS

We retrospectively reviewed MR images of patients with thyroid cancer with abnormal lymph nodes in the retropharyngeal and parapharyngeal spaces and determined the size and signal-intensity characteristics of these nodes. We reviewed patient charts for the following history: 1) thyroidectomy, 2) rising thyroglobulin levels, 3) iodine-131 radiation therapy, 4) neck dissection, and 5) pathology on neck sonography and chest CT. We reviewed pathology findings to determine if thyroid cancer metastases were present in these lymph nodes.

RESULTS

Eight patients had abnormal retropharyngeal space nodes, and 1 patient had a parapharyngeal space mass. Lymph nodes ranged from 7 to 25 mm. On MR imaging, 1 patient had a cystic node, 2 had complex nodes, and 6 had solid nodes. Eight patients had rising serum thyroglobulin levels and a history of thyroidectomy, radioiodine therapy, and neck dissection. Two of these patients had no pathologic nodes on sonography and normal findings on chest CT. Six patients had tissue sampling of their skull base node, and metastatic thyroid cancer was present in 5.

CONCLUSIONS

MR imaging of the neck should be considered in thyroidectomy patients with rising serum thyroglobulin levels and a history of radioiodine therapy and neck dissection. Radiologists should carefully examine the retropharyngeal and parapharyngeal spaces in these patients because nodal metastases may occur there more commonly than realized.

Use of an electronic nose for detection of biofilms

BACKGROUND

Prior work has indicated that electronic nose (enose) technology can distinguish among bacteria samples and identify patients with ventilator-associated pneumonia and rhinosinusitis. This study was performed to test the hypothesis that an enose can distinguish between biofilm-producing and non-biofilm-producing bacteria of the same species.

METHODS

Biofilm-producing and non-biofilm-producing mutant strains of Pseudomonas (PA01 and Sad36) and Staphylococcus (Staph WT and Staph SrtA-B-) were incubated and then sampled by the enose. Data were evaluated by logistic regression to perform binary classification of the bacteria. Training sets and testing sets were developed in two ways: by cross-validation with a leave-1-day-out method, and then by testing the last 4 days versus the first 18 days.

RESULTS

By the leave-1-day-out method, logistic regression analysis of 198 samples of each bacterium determined that the training accuracy of the enose for both Pseudomonas species was 100% and the testing accuracy was 91.4% for PA01 and 88.4% for Sad36. The training accuracy of the enose for Staphylococcus species was 87.1% for Staph SrtA-B- and 88.2% for Staph WT and the testing accuracy was, respectively, 75.3 and 76.8%. By separating the first 18 days from the last 4 days, logistic regression analysis determined that the training accuracy of the enose for both Pseudomonas species was 100% and the testing accuracy was 100% for PA01 and 80.6% for Sad36. The training accuracy of the enose for Staphylococcus species was 87.7% for Staph SrtA-B- and 86.4% for Staph WT and the testing accuracy was respectively, 72.2 and 91.7%.

CONCLUSION

The enose was able to identify correctly biofilm- versus non-biofilm-producing Pseudomonas and Staphylococcus species with accuracy ranging from 72.2 to 100%, depending on the particular organism and the data analysis methodology. These results suggest that biofilms may be an in vivo marker, which the enose can use to identify patients with particularly virulent and medically recalcitrant forms of chronic rhinosinusitis.

In vitro discrimination of tumor cell lines with an electronic nose

OBJECTIVE

The electronic nose is a sensor of volatile molecules that is useful in the analysis of expired gases. Our hypothesis is that the electronic nose can distinguish between different types of upper aerodigestive tract tumor cells in vitro.

STUDY DESIGN

Cells from both tumor and normal cell lines were suspended in saline, and a polymer composite electronic nose was used to evaluate the headspace gases. The data were subjected to principal components analysis, and Mahalanobis distances were calculated to demonstrate the ability of the electronic nose to distinguish among samples.

RESULTS

The tumor cell lines, including adenocarcinoma, squamous cell carcinoma, and mesothelioma, were distinct from each other, and from the normal fibroblast and smooth muscle cells as seen on canonical discrimination plots.

CONCLUSION

The electronic nose can distinguish between tumor cell lines in vitro and has the potential to be a useful screening test for cancer.

Use of an electronic nose to diagnose bacterial sinusitis

BACKGROUND

Having previously established that an electronic nose (enose) can distinguish among bacteria samples, between cerebrospinal fluid leak and serum, and can identify patients with ventilator-associated pneumonia, we hypothesized that bacterial sinusitis could be diagnosed by sampling exhaled gas with an enose.

METHODS

Using a nasal continuous positive airway pressure mask, we sampled gas exhaled through the nose of patients with sinusitis and compared them with controls. Data were first projected onto the principal components and then classified by support vector machine (SVM), a machine learning algorithm for pattern recognition.

RESULTS

SVM analysis showed good discrimination using three approaches. First, 11 samples were used to create a training set that was used to predict whether individual samples from each set were a member of the control or infected sets. The enose was correct 98.4% of the time. Second, one-half of the samples from each of the same 11 control and infected groups were used to construct a training set, which was used to predict infection in the remaining samples. The enose was correct 82% of the time. Finally, 68 samples (34 positive and 34 controls) were analyzed using a leave-one-out scheme for creating training sets and testing sets. This method, designed to reflect the generalization property of the SVM classifier, scored a classification rate of 72%.

CONCLUSION

Using the enose to sample nasal exhalation from patients with suspected sinusitis, we were able to predict correctly the diagnosis of sinusitis in at least 72% of the samples. The next step will be to do forward prediction using this model.

Medical applications of electronic nose technology

Electronic nose technology has been developed over the past 15 years in the field of chemistry as an electronic equivalent of the biologic mechanism of smell. Since its inception, it has been well recognized that there is great potential in applying this technology to the field of medicine. This review discusses those areas of medicine in which electronic nose technology has been applied. For each area, this review addresses the scope of the medical problem that has been studied, how the electronic nose technology may help address the medical problem, and the results of such studies to date. Next generation electronic noses will be refined to better analyze specific disease states. This will require further evaluation of the specific volatiles to be tested. This information may then be brought to bear on refinement of the chemistry of the electronic nose sensors, making them more sensitive and specific for the particular disease of interest. The ultimate goal of work in this arena is to make an electronic nose that is portable, fast, inexpensive and, therefore, suitable for use in the examination room or at the bedside, making it facile as a diagnostic tool.

Correlation of pneumonia score with electronic nose signature: A prospective study

OBJECTIVES

Ventilator-associated pneumonia (VAP) is a frequent complication in patients in surgical intensive care units. Pneumonia scores, chest radiography, and bronchoscopy are all employed, but there is no gold standard test for the diagnosis of VAP. The electronic nose, a sensor of volatile molecules, is well suited to testing the breath of mechanically ventilated patients. Our objective was to determine the potential use of an electronic nose as a diagnostic adjunct in the detection of VAP.

METHODS

We performed a prospective study of mechanically ventilated patients in a surgical intensive care unit. Clinical data, including temperature, white blood cell count, character and quantity of tracheal secretions, ratio of partial pressure of arterial oxygen to fraction of inspired oxygen, and chest radiographs, were collected, and a pneumonia score between 0 and 10 was calculated. Exhaled gas was sampled from the expiratory limb of the ventilator circuit. The gases were assayed with a commercially available electronic nose. Multidimensional data reduction analysis was used to analyze the results.

RESULTS

Forty-four patients were studied. Fifteen patients had pneumonia scores of 7 or greater, and 29 patients had scores of 6 or less. With Fisher discriminant analysis and K-nearest neighbor analysis, the electronic nose was able to discriminate between the two groups.

CONCLUSIONS

The electronic nose is a new technology that is inexpensive, noninvasive, and portable. We demonstrate its ability to predict pneumonia, based on a well-recognized scoring system. This technology promises to serve as a diagnostic adjunct in the management of VAP.

Differentiation between cerebrospinal fluid and serum with electronic nose

OBJECTIVE

The study investigates the ability of the electronic nose to differentiate between cerebrospinal fluid (CSF) and serum and to identify an unknown specimen as CSF or serum.

STUDY DESIGN AND SETTING

CSF and serum specimens were heated and tested with an organic semiconductor-based Cyranose 320 electronic nose (Cyrons Sciences, Pasadena, CA). Data from the 32-element sensor array were subjected to principal component analysis to depict differences in odorant patterns.

RESULTS

The electronic nose was able to distinguish between CSF and serum isolates with Mahalanobis distance >5. Furthermore, the electronic nose was able to place unknown specimens in the appropriate class of CSF or serum.

CONCLUSIONS

The electronic nose is a novel method that may allow rapid, low cost, and reliable distinction between CSF and serum in a clinical setting.

SIGNIFICANCE

Because the results are available almost immediately, the electronic nose is a powerful tool that in the future may allow for rapid diagnosis of CSF leaks in the office setting.

Editorial Board

OBJECTIVE

The study investigates the ability of the electronic nose to differentiate between cerebrospinal fluid (CSF) and serum and to identify an unknown specimen as CSF or serum.

STUDY DESIGN AND SETTING

CSF and serum specimens were heated and tested with an organic semiconductor-based Cyranose 320 electronic nose (Cyrons Sciences, Pasadena, CA). Data from the 32-element sensor array were subjected to principal component analysis to depict differences in odorant patterns.

RESULTS

The electronic nose was able to distinguish between CSF and serum isolates with Mahalanobis distance >5. Furthermore, the electronic nose was able to place unknown specimens in the appropriate class of CSF or serum.

CONCLUSIONS

The electronic nose is a novel method that may allow rapid, low cost, and reliable distinction between CSF and serum in a clinical setting.

SIGNIFICANCE

Because the results are available almost immediately, the electronic nose is a powerful tool that in the future may allow for rapid diagnosis of CSF leaks in the office setting.

Electronic nose prediction of a clinical pneumonia score: biosensors and microbes

BACKGROUND

The authors performed a prospective study to determine whether breath test analysis using an electronic nose correlates with a clinical pneumonia score.

METHODS

Exhaled gas was sampled from the expiratory limb of the ventilator in mechanically ventilated surgical intensive care patients and assayed with the electronic nose. Components of a clinical pneumonia score were recorded concurrently.

RESULTS

The score predicted by the electronic nose showed good correlation with the actual pneumonia score (r = 0.81). Bland Altman analysis showed a mean bias of 0.0 (limits +/- 2.6).

CONCLUSIONS

The electronic nose is a new biosensor technology that correlates with a clinical pneumonia score.