Undiagnosed Obstructive Sleep Apnea and Acute COVID-19 Infection—A Case Series

A recently published study on coronavirus disease 2019 (COVID-19) and obstructive sleep apnea (OSA) suggested that there might be an association between certain risk factors and comorbidities associated with OSA, which are also associated with poor COVID-19 outcomes. However, it is unclear whether undiagnosed OSA correlates with COVID-19 severity in a South Korean population. We identified 7 patients who presented with nocturnal hypoxemia during hospitalization due to COVID-19. All patients underwent polysomnography 5–9 weeks after the infection. We retrospectively collected the patients’ baseline characteristics, hospital admission data, and polysomnography findings. Of the 7 patients, all were diagnosed with OSA after COVID-19 infection. Their mean (±SD) age was 45.4±16.3 years, 57.1% were men, and their mean (±SD) body mass index was 33.4±6.0 kg/m2. Six patients presented with COVID-19-related pneumonia on chest X-rays, 3 of whom were admitted to the intensive care unit during the acute phase. The overnight polysomnography showed a mean AHI of 59.0±38.5/h and an oxygen desaturation index of 57.6±39.7/h. Undiagnosed OSA is a prevalent condition associated with moderate to severe COVID-19 infection. The study patients with sleep apnea and COVID-19 had obesity and severe oxygen desaturation but did not complain of daytime sleepiness.

Association and Risk Factors for Obstructive Sleep Apnea and Cardiovascular Diseases: A Systematic Review

Obstructive sleep apnea (OSA) is a serious, potentially life-threatening condition. Epidemiologic studies show that sleep apnea increases cardiovascular diseases risk factors including hypertension, obesity, and diabetes mellitus. OSA is also responsible for serious illnesses such as congestive heart failure, stroke, arrhythmias, and bronchial asthma. The aim of this systematic review is to evaluate evidence for the association between OSA and cardiovascular disease morbidities and identify risk factors for the conditions. In a review of 34 studies conducted in 28 countries with a sample of 37,599 people, several comorbidities were identified in patients with severe OSA—these were: heart disease, stroke, kidney disease, asthma, COPD, acute heart failure, chronic heart failure, hyperlipidemia, thyroid disease, cerebral infarct or embolism, myocardial infarction, and psychological comorbidities including stress and depression. Important risk factors contributing to OSA included: age > 35 years; BMI ≥ 25 kg/m2; alcoholism; higher Epworth sleepiness scale (ESS); mean apnea duration; oxygen desaturation index (ODI); and nocturnal oxygen desaturation (NOD). Severe OSA (AHI ≥ 30) was significantly associated with excessive daytime sleepiness and oxygen desaturation index. The risk of OSA and associated disease morbidities can be reduced by controlling overweight/obesity, alcoholism, smoking, hypertension, diabetes mellitus, and hyperlipidemia.

Burden of Comorbidities in Patients with OSAS and COPD-OSAS Overlap Syndrome

Background and Objectives: Obstructive sleep apnea syndrome (OSAS) and chronic obstructive pulmonary disease (COPD) are usually associated with multi-morbidity. The aim of this study was to retrospectively investigate the prevalence of comorbidities in a cohort of patients with OSAS and COPD-OSAS overlap syndrome (OS) patients and to explore differences between these two groups. Materials and Methods: Included were consecutive OS patients and OSAS patients who had been referred to our sleep laboratory, and were matched in terms of sex, age, BMI, and smoking history. Presence of comorbidities was recorded based on their medical history and after clinical and laboratory examination. Results: The two groups, OS patients (n = 163, AHI > 5/h and FEV1/FVC < 0.7) and OSAS patients (n = 163, AHI > 5/h, and FEV1/FVC > 0.7), did not differ in terms of apnea hypopnea index (p = 0.346), and oxygen desaturation index (p = 0.668). Compared to OSAS patients, OS patients had lower average SpO2 (p = 0.008) and higher sleep time with oxygen saturation <90% (p = 0.002) during sleep, and lower PaO2 (p < 0.001) and higher PaCO2 (p = 0.04) in wakefulness. Arterial hypertension was the most prevalent comorbidity for both OS and OSAS, followed by dyslipidemia, cardiovascular disease (CVD) and diabetes. OS was characterized by a higher prevalence of total comorbidities (median (IQR):2 (1–3) vs. 2 (1–2), p = 0.033), which was due to the higher prevalence of CVD (p = 0.016) than OSAS. No differences were observed in other comorbidities. Conclusions: In OS patients, nocturnal hypoxia and impaired gas exchange in wakefulness are more overt, while a higher burden of CVD is observed among them in comparison to sex-, age- and BMI-matched OSAS patients.

P064 The Impact of Artefact-free Recording Time on the Diagnosis of Sleep Disordered Breathing

Background Overnight studies are used to diagnose sleep disordered breathing (SDB), however the minimum artefact-free recording time (AFRT) has not been established in children. Aim To determine the impact of AFRT on SDB diagnoses. Methods Patients attended overnight cardiorespiratory polygraphy/polysomnography, alongside pulse oximetry sleep studies. Respiratory parameter reports were generated using the first 4, 5, 6 and 7 hours of AFRT. Predetermined clinically relevant cut-off (CRCO) values were defined: Obstructive AHI (OAHI; CRCO≥2); Central Apnoea-Hypopnoea Index (CAHI; CRCO≥5); 3% Oxygen Desaturation Index (ODI3%; CRCO≥6); 4% Oxygen Desaturation Index (ODI4%; CRCO≥4). Studies crossing CRCO across different AFRTs were described as ‘Cases of Change’ (COC). Receiver operating characteristic (ROC) curves determined ranges at 4 hours which predicted COC across subsequent AFRTs. Results 137 children (0.39–17.98 years) were consecutively recruited. Mean OAHI, CAHI, ODI3% and ODI4% were 1.54 (σ=2.66), 1.56 (σ=3.43), 5.21 (σ=6.53) and 2.77 (σ=4.42) respectively. For children achieving 7 hours AFRT (n=103), COC from 4 hours were: OAHI≥2 =9.7% (10/103); CAHI≥5 =2.9% (3/103); ODI3%≥6 =3.7% (4/109); ODI4%≥4 =1.8% (2/109). For OAHI≥2, optimal points on ROC curves for predicting COC provided a range of 0.875 (AUC= 0.733; 50% sensitivity; 93% specificity) - 3.125 (AUC= 0.968; 100% sensitivity; 81% specificity). Conclusion Four hours AFRT yields diagnostic results in &gt; 90% cases when commonly used cut-off criteria are applied. For OSA, ranges at 4 hours within which diagnostic change is most likely with longer periods of AFRT are provided. Consideration should be given to repeating short studies where values lie within these ranges.

P035 Is the Grael oximetry averaging time interchangeable with a Masimo pulse oximeter algorithm in polysomnography?

Compumedics recording software (Grael V2) for polysomnography (PSG) calculates SpO2 values using a 3-heartbeat long averaging window. This is derived from the ECG and thus introduces variability in the averaging time that is dependent on the heart rate. Little is known about the effect this has on the common oximetry metrics used in PSG interpretation. This study explorer the interchangeability of the Grael V2 inbuilt 3-beat averaging algorithm with a short averaging window of 2 - 4 seconds using a Masimo Radical 7 pulse oximeter during a PSG. SpO2 data were collected from 2 oximeter probes (Grael and Radical 7) both attached to a patient’s fingers. After SpO2 artifacts were removed, the following SpO2 parameters from each oximeter were generated: mean sleep SpO2, oxygen desaturation index (ODI) using 2%, 3% and 4% drop in SpO2 in sleep, total sleep time (TST) with SpO2 &lt; 90% and &lt; 80% as well as time spent &lt; SpO2 88% in minutes. 88 sleep studies were included in the data collection. For ODI2%, 3% and 4%, bias (95% limits of agreement) values were -0.75 events/hr (9.99 to -11.49 events/hr), -0.74 events/hr (10.00 - -11.49 events/hr) and -0.20 events/hr (8.45 - -8.86 events/hr) respectively. There was no significant difference between measurements except for the mean sleep SpO2 values, p &lt; .001. Although no bias found between measurements, there was poor agreement between the algorithms as demonstrated by the wide 95% limits of agreement suggesting that the two oximeter devices are not interchangeable.

O041 The impact of including oxygen desaturations occurring during awake epochs on the oxygen desaturation index

Introduction The oxygen desaturation index (ODI) is an important measure of sleep disordered breathing during polysomnography (PSG) however there is no accepted standard for its calculation. The AASM Manual for the Scoring of Sleep and Associated events (V2.6) does not specify whether oxygen desaturations occurring during awake epochs should be included. More generally, epoch-based scoring is potentially problematic for accurate ODI calculation. This study aims to compare the calculation of ODI including and excluding oxygen desaturations occurring during awake epochs and to determine the impact of sleep efficiency (SE) on any discrepancy. Methods Using twenty-one consecutive unattended PSG’s for investigation of OSA, two oxygen desaturation indices were calculated from each PSG; one excluding (ODIsleep) and one including (ODIall) oxygen desaturations marked in awake epochs. Results The median (IQR) ODIall was 19.3/h (10.3, 27.0) and ODIsleep was 13.0/h (6.6, 16.7). The median (IQR) difference (ODIall - ODIsleep) was 5.2/h (2.7, 10.4). This difference was greater with decreasing SE (r = -.63, p = .002). Patients with SE ≤ 75% (n=10) had a median ODI difference of 11.5/h (4.0, 17.6), and those with SE &gt; 75% (n=11) had a difference of 2.8/h (2.0, 5.5) (p = .02). Discussion ODI was greater when including oxygen desaturations during awake epochs, with this discrepancy being greatest when SE is ≤ 75%. We plan to confirm these findings in a larger sample. This investigation informs clinical practice, highlights the difficulties of epoch scoring, and informs future standards for the scoring of sleep and associated events.

Simple screening model for identifying the risk of sleep apnea in patients on opioids for chronic pain

BackgroundThere is an increased risk of sleep apnea in patients using opioids for chronic pain. We hypothesized that a simple model comprizing of: (1) STOP-Bang questionnaire and resting daytime oxyhemoglobin saturation (SpO2); and (2) overnight oximetry will identify those at risk of moderate-to-severe sleep apnea in patients with chronic pain.MethodAdults on opioids for chronic pain were recruited from pain clinics. Participants completed the STOP-Bang questionnaire, resting daytime SpO2, and in-laboratory polysomnography. Overnight oximetry was performed at home to derive the Oxygen Desaturation Index. A STOP-Bang score ≥3 or resting daytime SpO2 ≤95% were used as thresholds for the first step, and for those identified at risk, overnight oximetry was used for further screening. The Oxygen Desaturation Index from overnight oximetry was validated against the Apnea-Hypopnea Index (≥15 events/hour) from polysomnography.ResultsOf 199 participants (52.5±12.8 years, 58% women), 159 (79.9%) had a STOP-Bang score ≥3 or resting SpO2 ≤95% and entered the second step (overnight oximetry). Using an Oxygen Desaturation Index ≥5 events/hour, the model had a sensitivity of 86.4% and specificity of 52% for identifying moderate-to-severe sleep apnea. The number of participants who would require diagnostic sleep studies was decreased by 38% from Step 1 to Step 2 of the model.ConclusionA simple model using STOP-Bang questionnaire and resting daytime SpO2, followed by overnight oximetry, can identify those at high risk of moderate-to-severe sleep apnea in patients using opioids for chronic pain.Trial registration numberNCT02513836.

Sleep Study Measures on Postoperative Night 1 Following Implantation of the Hypoglossal Nerve Stimulator

Objective To examine the changes in measures of sleep apnea severity and hypoxemia on the first postoperative night following implantation of the hypoglossal nerve stimulator. Study Design This was a single-arm prospective cohort study. Setting A single academic sleep surgical practice. Methods Subjects with moderate to severe obstructive sleep apnea underwent implantation of the hypoglossal nerve stimulator (HGNS) and were discharged to home the same day as surgery. A single-night WatchPAT study was performed on the night immediately following surgery (PON 1) and was compared to baseline sleep testing. Results Twenty subjects who were an average of 58.6 ± 2.5 years old, were 25% female, and had a mean body mass index of 28.1 ± 0.9 kg/m2 completed the study. Mean O2 nadir at baseline was 79.6% ± 1.1% compared to 82.7% ± 0.9% ( P = .013) on PON 1. One patient demonstrated a >10% worsening in O2 nadir. Only 2 additional patients demonstrated a worsening in O2 nadir on PON 1, each by only 1 percentage point. Neither mean time spent below SpO2 88% nor oxygen desaturation index (ODI) worsened postoperatively (mean time spent below oxygen saturation of 88%, 27.8 ± 7.85 vs 11.2 ± 5.2, P = .03; mean ODI, 29.6 ± 5.2/h vs 21.0 ± 5.4/h, P = .10). Mean obstructive apnea hypopnea index (AHI) was no worse (40.6 ± 4.7/h to 28.7 ± 4.2/h, P = .02), with only 2 patients experiencing an obstructive AHI >20% more severe than baseline. Only 1 patient demonstrated a clinically meaningful increase in central AHI on PON 1. Conclusions Overall, AHI and measures of nocturnal hypoxemia are stable, if not improved, on PON 1 following HGNS implantation. These findings support the safety of same-day discharge following implantation of the hypoglossal nerve stimulator.