A Minimum Set of Physiological Parameters to Diagnose Obstructive Sleep Apnea Syndrome Using Non-Invasive Portable Monitors. A Systematic Review

Introduction. Despite its high accuracy, polysomnography (PSG) has several drawbacks for diagnosing obstructive sleep apnea (OSA). Consequently, multiple portable monitors (PMs) have been proposed. Objective. This systematic review aims to investigate the current literature to analyze the sets of physiological parameters captured by a PM to select the minimum number of such physiological signals while maintaining accurate results in OSA detection. Methods. Inclusion and exclusion criteria for the selection of publications were established prior to the search. The evaluation of the publications was made based on one central question and several specific questions. Results. The abilities to detect hypopneas, sleep time, or awakenings were some of the features studied to investigate the full functionality of the PMs to select the most relevant set of physiological signals. Based on the physiological parameters collected (one to six), the PMs were classified into sets according to the level of evidence. The advantages and the disadvantages of each possible set of signals were explained by answering the research questions proposed in the methods. Conclusions. The minimum number of physiological signals detected by PMs for the detection of OSA depends mainly on the purpose and context of the sleep study. The set of three physiological signals showed the best results in the detection of OSA.

413 Inpatient Sleep Screens: Effective for Screening but Poor Follow Up

Introduction Only 20% of adult Americans with Obstructive Sleep Apnea (OSA) are thought to have been diagnosed. Portable monitors (PM) can provide shorter time to diagnosis and treatment in at risk populations including inpatients. Data on inpatient sleep screen testing outcomes and population phenotypes are limited. We hypothesized that inpatients undergoing sleep screens via PM have higher disease severity but are less adherent to follow up. Methods We conducted a retrospective observational study comparing severity of OSA based on apnea-hypopnea index (AHI) and compliance with follow up between patients who received inpatient vs. outpatient sleep screens. There was a total of 347 patients, 18 years and older, who received a sleep screen from August 2017 to August 2018. Exclusion criteria were cancellations/no shows (13.56% inpatients vs. 13.51% outpatients) or loss of data (26.12% inpatients vs. 23.72% outpatients). For analysis, t-test and chi-square were used for continuous and categorical variables respectively. Results The patients diagnosed with severe OSA were more than double in the inpatient group vs. the outpatient group, 46.7% and 21.7% respectively. The inpatient group had a higher average AHI (30/h) compared to the outpatient group (20.3/h). 30.7% of the inpatient group were adherent with their follow up vs. 83.3% of the outpatient group. A chi-square test of independence demonstrated a significant difference between testing location and follow up (p < .001). Those in the inpatient group were significantly older (mean 60.4 years old) than the outpatient group (47.5 years old). There was no significant difference in gender between the groups. The inpatient group had significantly higher average body mass index (39.9 kg/m2) when compared to the outpatient group (34.3 kg/m2). Conclusion Hospitalized patients screened for OSA with portable monitors are significantly more likely to have severe disease when compared to outpatients. Despite this, adherence to follow up is poor. Systematic evaluation of inpatient OSA screening program effectiveness and factors impacting adherence to follow up and treatment are needed. Support (if any):

0619 To Rely or No to Rely: Understanding the Demographics and Polysomnographic Features of False Negative Home Sleep Apnea Testing

Introduction The current gold standard for a definitive diagnosis of OSA is an in-center Polysomnography (PSG). Home Sleep Apnea Testing(HSAT) has become an important tool in identifying high-risk populations. One of the limitations of the study is the lack of Electroencephalographic (EEG) data. This prevents the inclusion of Respiratory Effort Related Arousals (RERAs). We attempted to identify the patients whose HSAT showed an REI of less than 5 but are at risk for having sleep apnea based on the presence of airflow and thoraco-abdominal fluctuations. Methods Patients in this study were those that underwent HSAT from September 2016 till June of 2019. The studies reviewed and interpreted by board certified Sleep Specialists. Studies were done using nox-T3 sleep monitor and Nomad portable Home Sleep Testing type III devices-Both are type 3 Portable Monitors. Only those patients whose REI in their HSAT less than 5 were included in this study. All these patients had multiple airflow fluctuations in their HSAT that raised the suspicion for the presence of RERAs. None of these patients had significant hypoxemia in the HSAT.Airflow fluctuations were defined by the presence of fluctuations in the signal in the airflow channel along with increasing thoracoabdominal channels. Those patients with REI of less than 5 and without airflow fluctuations were excluded from the study. Results A total of 178 patients were recommended to undergo an in-center polysomnogram. Of those, 92 patients completed their polysomnogram with 59 patients ending up with a diagnosis of sleep apnea while 33 did not suggesting a false negative rate of 64.13%. Of those who were positive, 39 were females while 20 were males. Both groups did not differ significantly. Females had a median BMI of 32.9(28.19 for males), a median ESS of 11(8 in males) and a median RDI of 14.8(13.25). Conclusion Our study shows that both Home Sleep apnea testing can have a high proportion of false-negative results in patients exhibiting thoraco-abdominal and airflow fluctuations. The interpreting physicians should understand the limitations of the HSAT and should have a low threshold to recommend an in-center polysomnogram. Support None.

In-Cabin Vehicle Carbon Monoxide Concentrations under Different Ventilation Settings

This paper explores the impact of choice of ventilation setting (“window open”, “new (external) air” and “recirculate”) on in-vehicle carbon monoxide exposures for commuters travelling by car at different times of the day (morning, midday, and evening) and different seasons (warm and cool) in Auckland, New Zealand. Three near-identical vehicles travelled in close proximity to each other on the same three “loops” out and into the city three times a day, each with a different ventilation setting. Concentrations of carbon monoxide were recorded using portable monitors placed inside each of the vehicles. The season was not found to be a significant factor. However, mean concentrations varied across ventilation settings by the time of day, typically peaking during the morning commute. The mean concentrations were significantly different between ventilation settings, with the recirculate setting found to result in a higher in-vehicle concentration than either new air or windows open but also heavily dependent on the initial in-vehicle concentration. However, this setting was the most effective at avoiding concentration spikes, especially when idling at intersections; an isolated peak event reaching 170 ppm was observed with the “new air” setting when following immediately behind an old, poorly-tuned, and visibly-emitting vehicle. This study suggests that having the windows open is the best setting for maintaining low in-cabin air pollution levels but that recirculate should be used in anticipation of congested conditions.

Accuracy of Type III Portable Monitors for Diagnosing Obstructive Sleep Apnea

Objectives: We evaluated whether the results from portable monitor (PM) devices for the diagnosis of obstructive sleep apnea (OSA), classified into type III and type IV devices by the American Academy of Sleep Medicine, correlated with the results from polysomnography (PSG) testing. Methods: Sixty-four patients with a sleep-breathing disorder used type III or type IV PM devices at home and were subsequently admitted for testing using PSG. The apnea-hypopnea index (AHI) from each machine was measured, and the AHI component, apnea index (AI), and hypopnea index (HI) were also analyzed. Results: There was a stronger correlation between the AHI values from PSG testing and those from the type III PM devices (r = 0.92, p < 0.001) than for the data from type IV devices (r = 0.69, p < 0.001). However, the correlation of HI values (type III: r = 0.43, p = 0.024; type IV: r = 0.14, p = 0.41) was poorer than that of the AI values (type III: r = 0.95, p < 0.001; type IV: r = 0.68, p < 0.001). Moreover, the type III PM devices tended to evaluate a patient's condition as less severe than did PSG testing when the AHI value was over 30. Conclusions: Although type III PM devices outperformed type IV devices as substitutes for PSG, the clinical state must be evaluated for patients suspected of having obstructive sleep apnea.

Portable Monitor and Defibrillators (DRAFT)

Portable monitors with the capability of defibrillation, synchronized cardioversion, and transcutaneous pacing are frequently used by the rapid response teams (RRTs) in several acute care facilities to provide quick information and to treat lethal arrhythmias in critically ill and unstable patients. Portable monitors are used on lethal arrhythmias such as ventricular fibrillation (VF), monomorphic ventricular tachycardia (VT), or polymorphic ventricular tachycardia, also known as Torsades de pointes (TdP). Properly identifying lethal arrhythmias and knowing how to use the portable monitor/defibrillator is essential to positive patient outcomes. In this chapter, we review the use of portable monitors for monitoring and detection of cardiac arrhythmias as well as outline the procedure for defibrillation, synchronized cardioversion, and transcutaneous pacing in the setting of RRT activation.