Validation of self-applied unattended polysomnography using Somte V2 PSG (Somte) for diagnosis of obstructive sleep apnoea (OSA) in pregnant women in early to mid-gestation.

PURPOSE: Polysomnography (PSG) may be completed in the home environment (unattended), and when self-applied, allow the collection of data with minimal healthcare worker intervention. Self-applied, unattended PSG in the home environment using Somte PSG V2 (Somte) has not been validated in pregnant women in early to mid-gestation. We undertook a study to evaluate the accuracy of Somte compared to attended PSG. The agreement between apnoea hypopnea index (AHI) and respiratory disturbance index (RDI) scores in Somte and PSG in early to mid-gestation were assessed. METHODS: Pregnant women (≤ 24 weeks gestation) were scheduled for PSG and Somte within a 7-day window, in any order. Somte were self-applied and completed in the home. Somte were scored blinded to PSG result. AHI was the primary outcome of interest, though an AHI ≥ 5 or RDI ≥ 5 on PSG was considered diagnostic of Obstructive Sleep Apnoea (OSA). AHI, RDI, sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) was calculated and receiver operating characteristic (ROC) curves were produced. Bland-Altman plots were used to determine agreement. Technical issues occurring during tests were explored. RESULTS: Twenty-four participants successfully completed both tests between March 2021 and January 2023. PSG were completed at around 14.1 weeks' gestation (IQR 13.4, 15.7). The time interval between Somte and PSG was a median of 4 days (IQR 2, 7 (range 1-12)). Five (20.8%) women had OSA on PSG at AHI ≥ 5 and 10 (41.6%) women had OSA on PSG at RDI ≥ 5. Somte and PSG did not differ in the measurement of AHI ((1.8, 1.6, p = 0.09) or RDI (3.3, 3.5), p = 0.73). At AHI ≥ 5, diagnostic test accuracy (area under the ROC curve) of Somte was 0.94, sensitivity 80.0%, specificity 94.7%, PPV and NPV were 80.0% and 94.7% respectively. At RDI ≥ 5, diagnostic test accuracy (area under the ROC curve) was 0.95, sensitivity 60.0%, specificity 93.0% and PPV and NPV were 85.7% and 76.4% respectively. The confidence limits of Bland-Altman plots were 6.37 to - 8.89 at cut off AHI ≥ 5 and 8.89 to - 10.43 at cut off RDI ≥ 5. Somte failed to start in four tests. Technical issues were reported in both Somte (n = 13, 54.2%) and PSG (n = 6, 25.0%). CONCLUSION: Self-applied, unattended Somte may provide an acceptable substitute to attended PSG in the identification of OSA in pregnant women in early to mid-gestation in this small sample but may fail to detect cases of OSA, particularly when using RDI as the diagnostic marker.

Validation of the Apnealink Air for diagnosis of obstructive sleep apnoea (OSA) in pregnant women in early-mid gestation.

PURPOSE: The detection of obstructive sleep apnoea (OSA) in pregnant women in early-mid gestation is logistically difficult. Accurate alternates to polysomnography (PSG) in early pregnancy are not well identified. We compared the agreement between Apnealink Air (AL) and existing screening questionnaires to PSG in pregnant women ≤ 24-week gestation. METHODS: Pregnant women (≤ 24-week gestation) underwent AL at home plus attended PSG in any order, completed within 7 days where practicable. AL was manually scored (AL(M)) and automatically scored (AL(A)). An apnoea-hypopnea index (AHI) ≥ 5 was considered diagnostic of OSA and an AHI ≥ 15 considered at least moderate OSA. Diagnostic analysis was undertaken (sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV)) by generating receiver operating characteristic (ROC) curves and an area under the curve (AUC) (95% CI). Bland-Altman plots were used to plot agreement. Screening questionnaires (Epworth sleepiness score (ESS), STOP-BANG, calculated pregnancy-specific screening tool) were compared to PSG. RESULTS: A total of 49 participants successfully completed both tests at around 14-weeks gestation (IQR 12.9, 17.1). The time interval between AL and PSG was a median of 2 days (IQR 1, 5 (range 1-11)). A total of 14 (29%) participants had OSA. The median AHI of AL(A) (3.1(IQR 0.85,4.6)) and AL(M) (IQR2.4(0.65,4.8)) did not differ from PSG (1.7(IQR1.0,6.1)). AL(A) and AL(M) compared to PSG demonstrated diagnostic test accuracy (area under curve (ROC)) of 0.94(95% CI 0.87-1.0) and 0.92(95% CI 0.85-1.0) respectively. Apnealink Air outperformed screening questionnaires tested. CONCLUSION: The findings suggest that Apnealink may provide a substitute to attended PSG identification of OSA in pregnant women in early-mid gestation using both manual and auto-scoring methods.

Causes of hypercapnic respiratory failure: a population-based case-control study.

OBJECTIVE: There are no population-based data on the relative importance of specific causes of hypercapnic respiratory failure (HRF). We sought to quantify the associations between hospitalisation with HRF and potential antecedent causes including chronic obstructive pulmonary disease (COPD), obstructive sleep apnea, and congestive cardiac failure. We used data on the prevalence of these conditions to estimate the population attributable fraction for each cause. METHODS: A case-control study was conducted among residents aged ≥ 40 years from the Liverpool local government area in Sydney, Australia. Cases were identified from hospital records based on PaCO2 > 45 mmHg. Controls were randomly selected from the study population using a cluster sampling design. We collected self-reported data on medication use and performed spirometry, limited-channel sleep studies, venous sampling for N-terminal pro-brain natriuretic peptide (NT-proBNP) levels, and sniff nasal inspiratory pressure (SNIP) measurements. Logistic regression analyses were performed using directed acyclic graphs to identify covariates. RESULTS: We recruited 42 cases and 105 controls. HRF was strongly associated with post-bronchodilator airflow obstruction, elevated NT-proBNP levels, reduced SNIP measurements and self-reported opioid medication use. There were no differences in the apnoea-hypopnea index or oxygen desaturation index between groups. COPD had the highest population attributable fraction (42%, 95% confidence interval 18% to 59%). CONCLUSIONS: COPD, congestive cardiac failure, and self-reported use of opioid medications, but not obstructive sleep apnea, are important causes of HRF among adults over 40 years old. No single cause accounts for the majority of cases based on the population attributable fraction.

Prospective, observational study investigating the level of agreement between transcutaneous and invasive carbon dioxide measurements in critically ill emergency department patients.

BACKGROUND: Transcutaneous carbon dioxide (Ptcco2) measurement is a non-invasive surrogate marker for arterial carbon dioxide (Paco2), which requires invasive arterial blood sampling. Use of Ptcco2 has been examined in different clinical settings, however, most existing evidence in the adult emergency department (ED) setting shows insufficient agreement between the measurements. This study assessed the level of agreement between Ptcco2 and Paco2 in undifferentiated adult ED patients across multiple timepoints. METHODS: This prospective observational study (study period 2020-2021) assessed paired Ptcco2 and Paco2 measurements at four consecutive timepoints (0, 30, 60 and 90 min) in adult (aged 18 years or over) Australian ED patients requiring hospital admission and arterial catheter insertion. Agreement between the pairs was assessed using Bland-Altman analysis. It was prospectively determined by expert consensus that limits of ±4 mm Hg would be a clinically acceptable level of agreement between Ptcco2 and Paco2. RESULTS: During the study period 168 paired Ptcco2 and Paco2 readings were taken from 42 adult ED patients. Bland-Altman analysis showed a mean Ptcco2 reading 3.85 mm Hg higher than Paco2, although at each timepoint the 95% CIs breached the limit of 4 mm Hg difference. In addition, only 66% (111/168) of results fell within the clinically acceptable range. CONCLUSION: The level of agreement between Ptcco2 and Paco2 measurements may not be sufficiently precise for the adoption of Ptcco2 monitoring in patients presenting to the ED.

Causes of hypercapnic respiratory failure and associated in-hospital mortality.

BACKGROUND AND OBJECTIVE: Hypercapnic respiratory failure (HRF) can occur due to severe respiratory disease but also because of multiple coexistent causes. There are few data on the prevalence of antecedent causes for HRF and the effect of these causes on prognosis, especially where study inclusion has not been biased with respect to primary diagnosis, interventions received or clinical outcome. We sought to determine the prevalence of pre-specified conditions among patients with HRF and to determine the effect of these causes on in-hospital mortality. METHODS: Cross-sectional study of patients with HRF from 2013 to 2017. Inclusion criteria were PaCO2  >45 mm Hg and pH ≤7.45. Causes of interest were identified using diagnosis codes from hospital records. We used directed acyclic graphs to inform logistic regression models for the outcome of in-hospital death. RESULTS: We identified 873 persons with HRF in the study period. Mean (SD) age was 69 years and 50.4% were males. Acidosis (pH <7.35) was present in 488 (55%) cases. Most (83%) had one or more of the following: obstructive lung disease, lower respiratory tract infection, congestive cardiac failure, sleep disordered breathing, neuromuscular disease, opioid or benzodiazepine use. In-hospital mortality was 12.8%. Obstructive lung disease and cardiac failure were associated with a lower risk of death, whereas respiratory tract infection and neuromuscular disease were associated with increased risk of death. CONCLUSION: HRF is associated with a range of potentially causative conditions, which significantly impact hospital survival. Systematic evaluation of patients with HRF may increase detection of treatable comorbidities.

The Epworth sleepiness scale: Reliably unreliable in a sleep clinic population.

The Epworth Sleepiness Scale is used frequently to measure excessive daytime sleepiness in research and clinical settings, although there is limited evidence on test-retest reliability, particularly among sleep clinic populations. The objective of this study was to evaluate the reliability of this instrument among adult patients recruited from a public hospital sleep clinic in Sydney, Australia. English-speaking participants self-completed the Epworth Sleepiness Scale on two occasions, at the specialist clinic visit and on the night of diagnostic polysomnography. Of the 108 participants included in the study, the majority were male (64%) and the mean age was 51 years. The median retest interval was 64 days. The primary outcome of test-retest reliability as measured using the intraclass correlation coefficient was 0.73 (95% confidence interval, 0.61-0.82). Despite moderate statistical reliability and a low mean difference of 1.1, Bland-Altman analysis showed an unacceptably wide distribution of between-score differences. The 95% limits of agreement were -8.5 to +10.6, and an absolute difference in scores of at least 3 was observed in 60 (56%) of the participants. Our results suggest that the Epworth Sleepiness Scale should not be used in clinical settings to make individual-level comparisons, such as the effect of therapeutic interventions, or to prioritise access to services.

Supine awake oximetry as a screening tool for daytime hypercapnia in super-obese patients.

BACKGROUND: Evidence-based screening tools are required for detection of daytime hypercapnia in high-risk patient populations. AIMS: To determine the validity of supine awake oximetry as a test for daytime hypercapnia and severe sleep disordered breathing (SDB) in super-obese patients. METHODS: This was a cross-sectional diagnostic test evaluation of super-obese adults (body mass index >50 kg/m2 ) presenting to Liverpool Hospital, Australia, between 2009 and 2015 for diagnostic polysomnography (PSG) and arterial blood gas measurement. Supine awake oxygen saturation (SpO2 ) was determined using oximetry measurements from the first three awake epochs of raw PSG data. Sensitivity and specificity of SpO2 for detecting patients with daytime hypercapnia (PaCO2 >45 mmHg) and severe SDB (respiratory disturbance index (RDI) >30 events/h) were assessed at various cut-off points and displayed using a receiver operating characteristic (ROC) curve. Area under the ROC curve and positive and negative predictive values (PPV and NPV) in the present patient population were derived. RESULTS: Of 52 patients, 23 (44%) had daytime hypercapnia. SpO2 measured awake in the supine position was associated with the presence of daytime hypercapnia but not with the presence of severe SDB. Overall, awake supine SpO2 <91.2% had 34.8% sensitivity, 96.6% specificity and 88.8% PPV, and SpO2 <96.7% had 87.0% sensitivity, 20.7% specificity and 66.7% NPV for the presence of daytime hypercapnia. CONCLUSION: Awake supine oximetry is an easily performed test that may have novel use in identifying patients at high risk of respiratory failure. Future studies are required to evaluate prospectively its role in screening patients at risk of daytime hypercapnia.

Detection of microRNA as novel biomarkers of epithelial ovarian cancer from the serum of ovarian cancer patients.

OBJECTIVE: MicroRNA (miRNA) is an abundant class of small noncoding RNAs that act as gene regulators. Recent studies have suggested that miRNA deregulation is associated with the initiation and progression of human cancer. However, information about cancer-related miRNA is mostly limited to tissue miRNA. The aim of this study was to find specific profiles of serum-derived miRNAs of ovarian cancer based on a comparative study using a miRNA microarray of serum, tissue, and ascites. METHODS: From 2 ovarian cancer patients and a healthy control, total RNA was isolated from their serum, tissue, and ascites, respectively, and analyzed by a microarray. Under the comparative study of each miRNA microarray, we sorted out several miRNAs showing a consistent regulation tendency throughout all 3 specimens and the greatest range of alteration in serum as potential biomarkers. The availability of biomarkers was confirmed by qRT-PCR of 18 patients and 12 controls. RESULTS: Out of 2222 kinds of total miRNAs that were identified in the microarray analysis, 95 miRNAs were down-regulated and 88 miRNAs were up-regulated, in the serum, tissue, and ascites of cancer patients. Among the miRNAs that showed a consistent regulation tendency through all specimens and showed more than a 2-fold difference in serum, 5 miRNAs (miR-132, miR-26a, let-7b, miR-145, and miR-143) were determined as the 5 most markedly down-regulated miRNAs in the serum from ovarian cancer patients with respect to those of controls. Four miRNAs (miR-132, miR-26a, let-7b, and miR-145) out of 5 selected miRNAs were significantly underexpressed in the serum of ovarian cancer patients in qRT-PCR. CONCLUSIONS: Serum miR-132, miR-26a, let-7b, and miR-145 could be considered as potential candidates as novel biomarkers in serous ovarian cancer. Also, serum miRNAs is a promising and useful tool for discriminating between controls and patients with serous ovarian cancer.

Optimizing therapy with allopurinol: factors limiting hypouricemic efficacy.

The aim of this review is to examine clinical aspects of the use of the hypouricemic drug allopurinol. Allopurinol is a moderately active hypouricemic drug. Its activity is largely the result of the inhibition of xanthine oxidoreductase by oxypurinol, the active metabolite of allopurinol. The activity of allopurinol may be limited by oxypurinol, reducing the renal clearance of urate. Optimal use of allopurinol involves individualization of dose to attain a sufficient decrease in plasma urate concentrations. This may require a dose greater than recommended based on creatinine clearance. The initial use of an anti-inflammatory drug or low-dose colchicine decreases but does not eliminate the development of acute attacks of gout during the initiation of therapy with allopurinol. Monitoring of oxypurinol concentrations has shed some light on the efficacy of allopurinol but more data are required particularly in patients with renal impairment. Probenecid increases the hypouricemic effect of allopurinol but the favorable interaction may be significant only in patients with glomerular filtration rates greater than about 50 mL/min.