Power spectral analysis of the sleep electroencephalogram in positional obstructive sleep apnea.

OBJECTIVE/BACKGROUND: Previous studies have shown that obstructive sleep apnoea (OSA) is associated with reduced delta EEG and increased beta EEG power and increased EEG slowing ratio. There are however no studies that explore differences in sleep EEG between positional obstructive sleep apnoea (pOSA) and non-positional obstructive sleep apnoea (non-pOSA) patients. PATIENTS/METHODS: 556 of 1036 consecutive patients (246 of 556 were female) undertaking polysomnography (PSG) for the suspicion of OSA met the inclusion criteria for this study. We calculated power spectra of each sleep epoch using Welch's method with ten, 4-s overlapping windows. Outcome measures such as Epworth Sleepiness Scale, SF-36 Quality of Life, Functional Outcomes of Sleep Questionnaire and Pyschomotor Vigilance Task were compared between the groups. RESULTS: Patients with pOSA had greater delta EEG power in NREM and greater N3 proportions compared to their non-pOSA counterparts. There were no differences in theta (4-8Hz), alpha (8-12Hz), sigma (12-15Hz) or beta (15-25Hz) EEG power or EEG slowing ratio between the two groups. There were also no differences in the outcome measures between these two groups. The division of pOSA into spOSA and siOSA groups showed better sleep parameters in siOSA but with no difference in sleep power spectra. CONCLUSIONS: This study partially supports our hypothesis in showing that pOSA, compared to non-pOSA, is associated with increased delta EEG power but did not show any variation to beta EEG power or EEG slowing ratio. This limited improvement in sleep quality did not translate to measurable changes to outcomes, suggesting beta EEG power or EEG slowing ratio may be key factors.

The feasibility of using mouthpiece ventilation in the intensive care unit for post-extubation breathing support after acute tetraplegia.

STUDY DESIGN: A prospective cohort of patients with acute tetraplegia. OBJECTIVES: This study aimed to determine the feasibility of using mouthpiece ventilation (MPV) in the intensive care unit (ICU) for patients who are extubated after suffering an acute cervical spinal cord injury (CSCI). SETTING: ICU, Princess Alexandra Hospital, Brisbane Australia. METHODS: New admissions to ICU in the 14 months between April 2017 and June 2018 with a CSCI who underwent intubation were assessed for inclusion. MPV was provided to consenting participants (who were deemed likely to be able to maintain ventilation on their own) at the time of extubation and was utilised in addition to standard care while participants were awake. MPV settings, usage, and support hours to educate and facilitate MPV were collected. Feedback from participants and clinical staff was gathered throughout the study. Pre- and post-extubation measures of forced vital capacity (FVC), the frequency of endotracheal suction of sputum, and gas exchange using ventilation-perfusion ratios were recorded along with the incidence of reintubation. RESULTS: Fourteen participated in utilising MPV with 16 episodes of extubation. The average time per participant to have MPV titrated and bedside data collected was 178 minutes. Data from 16 episodes of extubation have been included. Three of the 14 participants failed initial extubation. Feedback from participants and clinicians has been positive and constructive, enabling MPV settings to be adapted to the person with acute CSCI during this pilot study. CONCLUSION: MPV is feasible to use post-extubation for people with CSCI in ICU. Pressure control mode MPV was deemed the most suitable for newly extubated acute CSCI patients. Intensive clinical support is required initially to provide education prior to MPV, and at the time of extubation for both patient and treating clinicians. Both report it to be a useful adjunct to ICU treatment.

Randomized controlled trial on the efficacy of audio-visual health educational materials on CPAP adherence: the AHEAD trial.

STUDY OBJECTIVES: Educational interventions have been proposed to improve continuous positive airway pressure (CPAP) adherence; however, studies to date have not demonstrated robust effectiveness, due to methodological issues. Furthermore, these educational interventions have not specifically targeted low health literacy communication techniques, which have been demonstrated to improve outcomes in numerous other chronic diseases. We hypothesized that the addition of low-cost audio-visual educational videos (EVs) to usual standard-of-care (SC) education would improve CPAP adherence in adults with obstructive sleep apnea (OSA) syndrome. METHODS: At CPAP initiation, treatment-naïve adults with OSA syndrome were randomized to (1) usual SC or (2) SC + 5 EVs showing a patient's journey, designed with low health literacy communication techniques to teach patients about OSA and CPAP therapy. The primary endpoint was CPAP usage at 2 months (hours/night) and secondary endpoints were CPAP usage at 12 months and percentage of patients with ≥ 4 hours/night use at 2 months and 12 months. RESULTS: One hundred and ninety-five patients were randomized (SC 99, EV 96), with a mean age of 57 years (interquartile range [IQR] 44.1-64.8 years). There were no statistically significant differences in patient characteristics at baseline between the SC vs EV groups, with the diagnostic apnea-hypopnea index of 34 events/h (IQR 21-59 events/h) vs 30 events/h (IQR 20-50 events/h) and Epworth Sleepiness Scale score of 12.8 ± 6 vs 11.7 ± 5. At 2 months, there was no significant difference in hours of CPAP usage (SC: 3.45 hours/night [95% confidence interval (CI): 2.76 to 4.13] vs EV: 3.75 hours/night [95% CI: 3.14 to 4.37]) nor in proportion with adequate usage or overall commencement rate. However, at 12 months, there was a significant difference in hours of CPAP usage (SC: 2.50 hours/night [95% CI: 1.94 to 3.06] vs EV: 3.66 hours/night [95% CI: 2.92 to 4.40]). The probability of adequate CPAP usage at 12 months was higher in the intervention arm (odds ratio: 1.33; 95% CI: 1.04 to 1.7; P = .013). Patients with low education backgrounds benefitted substantially from the EV intervention compared with SC (mean difference at 12 months = 2.47 hours/night usage; 95% CI: 1.01 to 2.93; P < .01). CONCLUSIONS: Low health literacy-designed EVs improve CPAP adherence at 12 months compared with SC, with the greatest impact in patients with a low educational background. CLINICAL TRIAL REGISTRATION: Registry: Australian New Zealand Clinical Trials Registry; Name: Randomised controlled trial on the efficacy of audio-visual health educational materials on sleep health literacy and continuous positive airway pressure (CPAP) adherence in Sleep Clinic patients; URL: https://www.australianclinicaltrials.gov.au/anzctr/trial/ACTRN12619000523101; Identifier: ACTRN12619000523101. CITATION: Ellender CM, Samaranayake C, Reid N, et al. Randomized controlled trial on the efficacy of audio-visual health educational materials on CPAP adherence: the AHEAD trial. J Clin Sleep Med. 2022;18(11):2617-2625.

Association between early stage N2 sleep spindle burst characteristics and vigilance groups: an observational study on patients from a tertiary sleep centre.

Objective.Obstructive sleep apnoea (OSA) is associated with impaired vigilance. This paper examines the hypothesis that sleep spindle (Sp) characteristics during nocturnal sleep can be mapped to vigilance deficits measured by the psychomotor vigilance task (PVT) in patients with OSA.Approach.The PVT was performed prior to In-laboratory Polysomnography for 250 patients. PVT outcomes were clustered into three vigilance groups (VGs). Spindles were scored manually for a Training Cohort of 55 patients, (9491 Sps) across different blocks of NREM sleep (SBs) and validated in a Test Cohort (25 patients, 4867 Sps). We proposed a novel set of Sp features including a spindle burst index (SBI), which quantifies the burst characteristics of spindles and constructed models mapping them to VGs. We also explored the performance of conventional Sp features (such as Sp number and density) in our modelling approach.Main results.In the Training Cohort, we observed statistically significant differences in the SBI across VGs and SBs independent of OSA severity (1st stage N2 SBI;p= <0.001 across VGs). In the Test Cohort, a Model based on the proposed SBI predicted VG membership with 88% accuracy. A model based on conventional Sp features mapped to VGs with 80% accuracy, and a model using mixed burst and conventional features reached an accuracy of 88%.Significance.Spindle features measured during diagnostic In-laboratory polysomnography measurements can be mapped to PVT outcomes. The novel SBI proved useful for exploring the relationship between PVT outcomes and sleep. Further studies in larger populations are needed to verify these conclusions.

Usefulness of self-administered questionnaires in screening for direct referral for polysomnography without sleep physician review.

STUDY OBJECTIVES: To evaluate self-administered screening questionnaires (Epworth Sleepiness Scale [ESS], Berlin, OSA50, and STOP-Bang questionnaires) in patients considered for polysomnography for probable obstructive sleep apnea suitable for direct polysomnography without sleep specialist review and to evaluate the usefulness of combining questionnaires in this population. METHODS: This was a retrospective review of tertiary sleep center referrals (November 2017 to April 2020) where ≥ 3 screening questionnaires were completed and type 1 polysomnography was performed. Sensitivity, specificity, positive and negative predictive values, and likelihood ratios to detect an apnea-hypopnea index (AHI) ≥ 15 or ≥ 30 events/h were calculated for each questionnaire (with or without ESS ≥ 8) or any positive questionnaire with ESS ≥ 8. RESULTS: We included 2,152 patients. The questionnaires were completed in the majority (ESS 96%, Berlin 77%, OSA50 84%, and STOP-Bang 90%) of referrals. Berlin was most sensitive (82.5% and 85% to detect AHI ≥ 15 and ≥ 30 events/h, respectively) but least specific (23% both thresholds). STOP-Bang was least sensitive (66% and 42%, respectively) but most specific (68% and 60%, respectively). Sensitivity declined for the Berlin, OSA50 and STOP-Bang questionnaires when combined with ESS ≥ 8. Combining any questionnaire with ESS ≥ 8 returned an intermediate sensitivity of 61% and 73% and a specificity of 49% and 47% for AHI ≥ 15 and ≥ 30 events/h, respectively. STOP-Bang alone was predictive of obstructive sleep apnea on multivariate analysis but was only associated with a clinically nonsignificant positive likelihood ratio. However, STOP-Bang is associated with unacceptable false-positive and -negative rates, which did not support its use. CONCLUSIONS: Self-administered questionnaires are inadequate in patients under consideration for polysomnography and should not be used as clinical support for suitability of direct polysomnography without sleep specialist review. Combining questionnaires causes deteriorated performance. CITATION: Hukins C, Duce B. Usefulness of self-administered questionnaires in screening for direct referral for polysomnography without sleep physician review. J Clin Sleep Med. 2022;18(5):1405-1412.

Adequate health literacy is associated with adherence to continuous positive airway pressure in adults with obstructive sleep apnea.

Study Objectives: Obstructive sleep apnea (OSA) is a chronic disease with significant health implications and adequate adherence to continuous positive airway pressure (CPAP) is essential for effective treatment. In many chronic diseases, health literacy has been found to predict treatment adherence and outcomes. In this study, the aim was to determine the health literacy of a sleep clinic population and evaluate the association between health literacy and CPAP adherence. Methods: A prospective cohort study was undertaken, recruiting 104 consecutive patients with a variety of sleep diagnoses. The Short Form Rapid Estimate of Adult Literacy in Medicine (REALM-SF), a validated questionnaire, was administered to measure health literacy. In a sub-group of 91 patients prescribed CPAP for OSA, CPAP usage was measured, with adequate usage defined as greater than 4 h/night CPAP therapy. Results: Seventy-one percent of the sleep clinic cohort was found to have adequate health literacy, as measured by the REALM-SF. In those prescribed CPAP for OSA, inadequate health literacy was associated with a twofold increased risk for inadequate CPAP usage (adjusted odds ratio [OR] 2.9, 95% CI: 1.1 to 8.22, p = 0.045). There was a 1.7 h/night difference in median CPAP usage comparing those with adequate to inadequate health literacy (4.6 h vs. 6.3 h/night). Conclusions: The majority of this sleep disorders cohort had adequate health literacy as measured by the REALM-SF questionnaire. However, inadequate health literacy appears to be an independent predictor of treatment adherence and may represent a modifiable risk factor of poor treatment outcomes in OSA.

Polysomnographic risk factors for vigilance-related cognitive decline and obstructive sleep apnea.

PURPOSE: Cognitive decline (CD) and obstructive sleep apnea (OSA) are often comorbid. Some modifiable risk factors (RF) for CD are also associated with OSA. Diagnostic polysomnography (PSG) measures these RF and may identify at risk patients prior to the onset of CD. We aim to determine whether there are severe RF associated with established CD and an increasing severity of OSA that could identify patients at risk for CD for medical intervention. METHODS: We gathered information from subjects having type 1 PSG for suspected OSA. The psychomotor vigilance task (PVT) measured established CD (group 0 and group1). We compared levels of severe RF in group 0 and group 1 with a larger group (group 2) without the PVT. We used severe standardized values of excessive daytime sleepiness (Epworth Sleepiness Score [ESS]), overnight change of systolic blood pressure (ΔSBP), change of oxygen desaturation (ΔSpO2), and sleep arousal (ArI) as RF. We compared the severe levels of ESS, ΔSBP, ΔSpO2, and ArI by group and OSA severity. RESULTS: A total of 136 patients underwent diagnostic PSG. PVT parameters were available for 43 subjects. The severity of the RF was consistent with risk for CD (ΔSBP 22.0 ± 5.6, ESS 18.2 ± 2.2, ArI 58.8 ± 18.7, ΔSpO2 61.7 ± 21.9). The levels of RF increased with increasing severity of OSA. There were significant between-group differences for severe ΔSpO2 (p = 0.004) and ΔSpO2 + ArI (p = 0.019). CONCLUSION: The levels of RF increase with increasing OSA severity. Subjects with severe RF ΔSpO2 and ΔSpO2 + ArI are likely to have PVT-determined CD. Risk factor analysis may screen for CD.

Asset life span in a government funded CPAP device program.

STUDY OBJECTIVES: To determine the life span of devices in a government long-term continuous positive airway pressure (CPAP) device loan program. METHODS: Retrospective review of CPAP devices provided under the Queensland Health Sleep Disorders program in Queensland, Australia, from data recorded in an in-house database that has collected data since 1995. Primary outcomes were hours of use and age of device at end-of-life. Device survival analysis was performed collectively for all devices and for different models. Reasons for device end-of-life were compared between models. RESULTS: There were 9,222 CPAP devices provided on long-term loan over this period, with asset end-of-life date available in 90%. Median life span was 15,178 hours (interquartile range 8,167-20,296 hours) and 12.4 (interquartile range 7.6-18.8) years. Five percent of devices were condemned in the first 3 years, and 13% of devices were condemned in the first 5 years. There were significant differences in survival patterns between different models, but after correction for run hours, only one model differed (related to manufacturer policy to replace not repair equipment). Reasons for end-of-life differed between models (P < .001) with manufacturer recall, excessive noise and faulty buttons the most common reasons. CONCLUSIONS: Government CPAP loan programs can develop asset management plans with an anticipated average asset life span of 15,178 hours or 12.4 years; however, they should also plan for the need to replace equipment where earlier failure occurs. Early equipment failures are seen with variability between models, and appropriate warranty periods to cover these early failures should be negotiated with manufacturers.

Longer duration electroencephalogram arousals have a better relationship with impaired vigilance and health status in obstructive sleep apnoea.

PURPOSE: Obstructive sleep apnoea (OSA) is a prevalent sleep disorder with significant health consequences. Sleep fragmentation is a feature of OSA and is often determined by the arousal index (ArI), a metric based on the electroencephalograph (EEG). The ArI has a weak correlation with neurocognitive outcomes in OSA patients. In this study, we examine whether changing from the current minimum EEG arousal duration of 3 s improves the association between sleep fragmentation and neurocognitive outcomes. METHODS: In a retrospective study, we selected OSA patients without any other comorbidities that are associated with neurocognitive impairment. The OSA patients were clustered into two groups based on their psychomotor vigilance task (PVT) performance to represent impaired and unimpaired neurocognition. RESULTS: While no differences were found in demographics or usual sleep study statistics, the impaired group had a greater number of EEG arousals greater than 5 s (P = 0.034), 7 s (P = 0.041), and 15 s (P = 0.036) in duration. There were no differences in the number of EEG arousals associated with sleep-disordered breathing events. These differences also corresponded with quality of life outcomes between the two groups. An ArI with a duration of 5 s or greater had the best combination of sensitivity (70.0%) and specificity (66.7%) compared with the usual 3 s duration (sensitivity and specificity of 70.0% and 53.3%, respectively). CONCLUSION: A re-examination of the EEG arousal scoring rules, and their duration, may help with allocation of health resources to OSA patients most in need.

Overnight airway obstruction severity prediction centered on acoustic properties of smart phone: validation with esophageal pressure.

OBJECTIVE: Obstructive sleep apnea is characterized by a number of airway obstructions. Esophageal pressure manometry (EPM) based estimation of consecutive peak to trough differences (ΔPes) is the gold standard method to quantify the severity of airway obstructions. However, the procedure is rarely available in sleep laboratories due to invasive nature. There is a clinical need for a simplified, scalable technology that can quantify the severity of airway obstructions. In this paper, we address this and propose a pioneering technology, centered on sleep related respiratory sound (SRS) to predict overnight ΔPes signal. APPROACH: We recorded streams of SRS using a bedside iPhone 7 smartphone from subjects undergoing diagnostic polysomnography (PSG) studies and EPM was performed concurrently. Overnight data was divided into epochs of 10 s duration with 50% overlap. Altogether, we extracted 42 181 such epochs from 13 subjects. Acoustic features and features from the two PSG signals serve as an input to train a machine learning algorithm to achieve mapping between non-invasive features and ΔPes values. A testing dataset of 14 171 epochs from four new subjects was used for validation. MAIN RESULTS: The SRS based model predicted the ΔPes with a median of absolute error of 6.75 cmH2O (±0.59, r = 0.83(±0.03)). When information from the PSG were combined with the SRS, the model performance became: 6.37cmH2O (±1.02, r = 0.85(±0.04)). SIGNIFICANCE: The smart phone based SRS alone, or in combination with routinely collected PSG signals can provide a non-invasive method to predict overnight ΔPes. The method has the potential to be automated and scaled to provide a low-cost alternative to EPM.

Incidence of hippocampal metastases in non-small-cell lung cancer.

OBJECTIVES: Patients with locally advanced non-small-cell lung cancer (LA-NSCLC) develop brain metastases in 25-50% of cases during the course of their disease. Data on the incidence of metastases occurring in the hippocampus/perihippocampal zones are limited. This is important when considering hippocampal-sparing brain radiation (HS-BR), a method that could potentially reduce the neurocognitive impact of such treatment. The aim of this study was to assess the incidence of hippocampal/perihippocampal metastases in a cohort of patients with advanced NSCLC treated at our institution. METHODS: This retrospective cohort study included NSCLC patients discussed at our institutional lung cancer multidisciplinary meeting between 2000 and 2016. MRI and contrast-enhanced CT (ceCT) brain images were reviewed to assess the incidence of hippocampal/perihippocampal metastases including metastases within the hippocampal subgranular zone and a 5 mm margin (hippocampal avoidance region) defined as per the RTOG 0933 study. RESULTS: Of 2146 patients reviewed, 357 (16.6%) had brain metastases. A total of 335 patients had available MRI/ceCT brain images for review. Thirty (9%) patients had brain metastases in the hippocampal avoidance region, 8 (2.4%) with hippocampal metastases and 22 (6.6%) with perihippocampal metastases. Univariate analyses did not show an association between developing metastases in the hippocampal avoidance region and age (P = 0.75), gender (P = 0.91) and tumour type (P = 0.298). CONCLUSION: The incidence of metastases in the hippocampal avoidance region in our large cohort of patients was 9%. With low rates of metastases in this region, HS-BR can be considered a feasible option in the management of patients with advanced NSCLC.

Noninvasive ventilation usage time and survival rate in patients with acute respiratory failure: some key insights.

Dose-response characteristics of noinvasive ventilation differ between hypoxaemic and hypercapnic respiratory failure https://bit.ly/2SYitiC.

Double-Triggering During Noninvasive Ventilation in a Simulated Lung Model.

BACKGROUND: Double-triggering is a well-recognized form of patient-ventilator asynchrony in noninvasive ventilation (NIV). This benchtop simulated lung study aimed to determine under which patient and device-specific conditions double-triggering is more prevalent, and how this influences the delivery of NIV. METHODS: Two commonly used proprietary NIV devices were tested using a benchtop lung model. Lung compliance, airway resistance, respiratory effort, and breathing frequency were manipulated, and the frequency of double-triggering was assessed. A lung model of very low lung compliance (15 mL/cm H2O) was then used to assess the frequency of double-triggering when breathing frequency and respiratory effort were varied, along with basic NIV settings, including inspiratory pressure and expiratory pressure. Minute ventilation and total inspiratory work (as calculated by the simulated lung model) were also correlated with frequency of double-triggering. RESULTS: In both devices, double-triggering was observed with reduced lung compliance (P = .02 and P < .001 for the two devices, respectively). Reduced airway resistance was associated with double-triggering with the one device only (P = .02). Respiratory effort and breathing frequency were not independent predictors of double-triggering across all lung models. In the lung model of very low lung compliance, both devices showed increased double-triggering at a lower breathing frequency (P < .001 and P < .001), higher respiratory effort (P = .03 and P < .001), and greater pressure support (P = .044, P < .001). Importantly, double-triggering was associated with reduced minute ventilation (P = .007) with one device and increased inspiratory work (P < .001) with the other device. CONCLUSIONS: Both simulated-patient and device characteristics influenced the frequency of double-triggering in NIV, resulting in meaningful consequences in a simulated lung model.

Dose-response characteristics of noninvasive ventilation in acute respiratory failure.

Acute noninvasive ventilation (NIV) is a well-established therapy for acute respiratory failure but the dose-response characteristics of this therapy have not been defined. The aim of this study was to define this dose-response relationship. This study was a retrospective review of patients receiving NIV for acute respiratory failure in a tertiary hospital respiratory high-dependency unit between July 2012 and June 2017. Mask-on time (rather than the period that NIV was in use) as the "dose" was compared with hospital survival as the "response". 654 patients were included, 594 (91%) with hypercapnic respiratory failure (HCRF). NIV was used for a median (interquartile range (IQR)) duration of 2.74 (1.51-4.73) days and median (IQR) mask-on time was 34 (18-60) h (56.1% (41.2-69.5%) of treatment time). There was evidence of a dose-response relationship in the HCRF group up to a ceiling of 24 h mask-on time, but not in the hypoxaemic respiratory failure (HRF) group. There was a difference in survival with as little as 2 h mask-on time (92% compared with 73%; p<0.001). Patients requiring NIV for 80-100% of therapy time had lower survival. We conclude that there is evidence of a dose-response relationship between cumulative NIV usage (mask-on time) and survival from as little as 2 h to a ceiling of ∼24 h in HCRF, but not in HRF.

Corrigendum: Predicting spirometry readings using cough sound features and regression (2018 Physiol. Meas. 39 095001).

The purpose of this submission is to provide missing information to complete the conflict of interest statement associated with the article. The statements provided here augment the already provided information rather than replace it.

A randomised crossover trial comparing nasal masks with oronasal masks: No differences in therapeutic pressures or residual apnea-hypopnea indices.

In treating obstructive sleep apnea (OSA), the use of oronasal masks with continuous positive airway pressure (CPAP) has been reported to increase pressure levels and reduce compliance. These reports come mostly from large observational studies. In this study, we examined the impact that oronasal masks have on 95th centile pressures, the residual apnea-hypopnea index (AHI) and compliance compared with nasal masks. A randomised crossover design was implemented. Participants already established on CPAP were randomly allocated to a nasal mask or oronasal mask with auto-titrating positive airway pressure (APAP) for 2 weeks. Participants then crossed over to use the alternate mask for another 2 weeks. Seventy-one participants were recruited but only 60 completed the trial. There were no differences in median 95th centile pressure (nasal, 11.5 cm H2 O; oronasal, 11.7 cm H2 O; p = 0.115), median residual AHI (nasal, 4.9 events/hr; oronasal, 5.3 events/hr; p = 0.234) or median compliance (nasal, 7.3 hr/night; oronasal, 7.3 hr/night; p = 0.961). Only four patients had 95th centile pressures that were at least 1.5 cm H2 O greater with oronasal masks. Oronasal masks do not systematically increase therapeutic CPAP requirements. Rather, a small subset of patients display significant differences in CPAP levels.

An Investigation of Critical Frequency Sub-bands of Snoring Sounds for OSA Diagnosis.

Obstructive Sleep Apnea (OSA) is a result of upper airway narrowing during sleep. The upper airway characteristics are likely to manifest in the acoustic characteristics of snoring sounds as snoring is a result of upper airway structure vibrations. In previous studies, researchers have used different regions of the frequency spectrum to diagnose OSA and determine sites of obstruction as well. However, there is no agreement among researchers about the frequency ranges critical for OSA diagnosis. This paper provides the results of a study of snore sound based OSA diagnosis performance using a multiple acoustic features and multiple classifiers. The results of the study may provide useful insights for researchers to identify frequency sub-bands critical for OSA diagnosis.

Predicting spirometry readings using cough sound features and regression.

OBJECTIVE: Spirometry is a commonly used method of measuring lung function. It is useful in the definitive diagnosis of diseases such as asthma and chronic obstructive pulmonary disease (COPD). However, spirometry requires cooperative patients, experienced staff, and repeated testing to ensure the consistency of measurements. There is discomfort associated with spirometry and some patients are not able to complete the test. In this paper, we investigate the possibility of using cough sound analysis for the prediction of spirometry measurements. APPROACH: Our approach is based on the premise that the mechanism of cough generation and the forced expiratory maneuver of spirometry share sufficient similarities enabling this prediction. Using an iPhone, we collected mostly voluntary cough sounds from 322 adults presenting to a respiratory function laboratory for pulmonary function testing. Subjects had the following diagnoses: obstructive, restrictive, or mixed pattern diseases, or were found to have no lung disease along with normal spirometry. The cough sounds were automatically segmented using the algorithm described in Sharan et al (2018 IEEE Trans. Biomed. Eng.). We then represented cough sounds with various cough sound descriptors and built linear and nonlinear regression models connecting them to spirometry parameters. Augmentation of cough features with subject demographic data is also experimented with. The dataset was divided into 272 training subjects and 50 test subjects for experimentation. MAIN RESULTS: The performance of the auto-segmentation algorithm was evaluated on 49 randomly selected subjects from the overall dataset with a sensitivity and PPV of 84.95% and 98.51%, respectively. Our regression models achieved a root mean square error (and correlation coefficient) for standard spirometry parameters FEV1, FVC, and FEV1/FVC of 0.593L (0.810), 0.725L (0.749), and 0.164 (0.547), respectively, on the test dataset. In addition, we could achieve sensitivity, specificity, and accuracy of 70% or higher by applying the GOLD standard for COPD diagnosis on the estimated spirometry test results. SIGNIFICANCE: The experimental results show high positive correlation in predicting FEV1 and FVC and moderate positive correlation in predicting FEV1/FVC. The results show possibility of predicting spirometry results using cough sound analysis.

Snore Sound Analysis Can Detect the Presence of Obstructive Sleep Apnea Specific to NREM or REM Sleep.

STUDY OBJECTIVES: Severities of obstructive sleep apnea (OSA) estimated both for the overall sleep duration and for the time spent in rapid eye movement (REM) and non-rapid eye movement (NREM) sleep are important in managing the disease. The objective of this study is to investigate a method by which snore sounds can be analyzed to detect the presence of OSA in NREM and REM sleep. METHODS: Using bedside microphones, snoring and breathing-related sounds were acquired from 91 patients with OSA (35 females and 56 males) undergoing routine diagnostic polysomnography studies. A previously developed automated mathematical algorithm was applied to label each snore sound as belonging to either NREM or REM sleep. The snore sounds were then used to compute a set of mathematical features characteristic to OSA and to train a logistic regression model (LRM) to classify patients into an OSA or non-OSA category in each sleep state. The performance of the LRM was estimated using a leave-one-patient-out cross-validation technique within the entire dataset. We used the polysomnography-based diagnosis as our reference method. RESULTS: The models achieved 80% to 86% accuracy for detecting OSA in NREM sleep and 82% to 85% in REM sleep. When separate models were developed for females and males, the accuracy for detecting OSA in NREM sleep was 91% in females and 88% to 89% in males. Accuracy for detecting OSA in REM sleep was 88% to 91% in females and 89% to 91% in males. CONCLUSIONS: Snore sounds carry sufficient information to detect the presence of OSA during NREM and REM sleep. Because the methods used include technology that is fully automated and sensors that do not have a physical connection to the patient, it has potential for OSA screening in the home environment. The accuracy of the method can be improved by developing sex-specific models.

Non-small cell lung cancer brain metastasis screening in the era of positron emission tomography-CT staging: Current practice and outcomes.

INTRODUCTION: Several clinical guidelines indicate that brain metastasis screening (BMS) should be guided by disease stage in non-small cell lung cancer (NSCLC). We estimate that screening is performed more broadly in practice, and patients undergo brain imaging at considerable cost with questionable benefit. Our aim was to quantify the use and detection rate of BMS in a contemporary cohort staged with 18 F-fluorodeoxyglucose positron emission tomography/computed tomography (PET-CT). METHODS: We conducted a retrospective review of prospectively collected data from three major lung cancer referral centres in Brisbane between January 2011 and December 2015. Patients included had a new diagnosis of NSCLC and had undergone a PET-CT to stage extra-cranial disease. BMS was defined as dedicated brain imaging with contrast-enhanced computed tomography (CE-CT) or magnetic resonance (MR), in the absence of clinically apparent neurological deficits. RESULTS: A total of 1751 eligible cases were identified and of these 718 (41%) underwent BMS. The majority had CE-CT imaging (n = 703). Asymptomatic brain metastases (BM) were detected in 18 patients (2.5%). Of these patients, 12 had concurrent non-brain metastases. Only six patients (0.8%) had BM alone. The rate of detection increased with N-stage (P = 0.02) and overall stage (P < 0.001). It was 0.5%, 1%, 1.6% and 7.3% for stage I, II, III and IV respectively. The overall screening rate increased with T-stage (P = 0.001), N-Stage (P < 0.001) and overall stage (P < 0.001). CONCLUSIONS: Non-small cell lung cancer BMS practices remain at odds with published guidelines. The low number of occult BMs detected supports the existing international recommendations. Rationalising BMS would minimise the burden on patients and the health care system.