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.

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.

Prevalence and factors associated with advanced care directives in a motor neuron disease multidisciplinary clinic in Australia.

OBJECTIVES: Motor neuron disease (MND) is a neurodegenerative disorder leading to functional decline and death. Multidisciplinary MND clinics provide an integrated approach to management and facilitate discussion on advanced care directives (ACDs). The study objectives are to analyse (1) the prevalence of ACD in our MND clinic, (2) the relationship between ACD and patient demographics and (3) the relationship between ACD decision-making and variables such as NIV, PEG, hospital admissions and location of death. METHODS: Using clinic records, all patients who attended the MND clinic in Liverpool Hospital between November 2014 and November 2019 were analysed. Data include MND subtypes, symptom onset to time of diagnosis, time of diagnosis to death, location and reason of death. ACD prevalence, non-invasive ventilation (NIV) and percutaneous endoscopic gastrostomy (PEG) requirements were analysed. RESULTS: There were 78 patients; M:F=1:1. 44 (56%) patients were limb onset, 28 (36%) bulbar onset, 4 primary lateral sclerosis and 2 flail limb syndrome presentations. 27% patients completed ACDs, while 32% patients declined ACDs. Patients born in Australia or in a majority English-speaking country were more likely to complete ACDs compared to those born in a non-English-speaking country. There was no significant correlation between ACD completion and age, gender, MND subtype, symptom duration, NIV, PEG feeding, location of death. CONCLUSION: One-quarter of patients completed ACDs. ACDs did not correlate with patient age, gender, MND subtype and symptom duration or decision-making regarding NIV, PEG feeding or location of death. Further studies are needed to address factors influencing patients' decisions regarding ACDs.

A foreign body experience.

Foreign body inhalation (FBI) is an uncommon clinical entity in adults. Despite this, FBI is an under-recognized, serious, and easily treatable condition. The authors report a case of a 31-year-old female asthmatic who presented with wheeze and cough not responding to therapy. Chest computed tomography and bronchoscopy confirmed a foreign body distal to the left upper lobe vestibule. The non-organic material was removed with rigid bronchoscopy and cryoprobe with resolution of symptoms. FBI remains an important differential in those presenting with respiratory symptoms in the absence of other diagnoses.

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.

Magnesium supplementation for the treatment of restless legs syndrome and periodic limb movement disorder: A systematic review.

Magnesium supplementation is often suggested for restless legs syndrome (RLS) or period limb movement disorder (PLMD) based on anecdotal evidence that it relieves symptoms and because it is also commonly recommended for leg cramps. We aimed to review all articles reporting the effects of magnesium supplementation on changes in RLS and/or PLMD. We conducted a systematic search looking for all relevant articles and then two reviewers read all article titles and abstracts to identify relevant studies. Eligible studies were scored for their quality as interventional trials. We found 855 abstracts and 16 of these could not be definitively excluded for not addressing all aspects of our research question. Seven full-text articles were unlocatable and one was ineligible which left eight studies with relevant data. One was a randomised placebo-controlled trial, three were case series and four were case studies. The RCT did not find a significant treatment effect of magnesium but may have been underpowered. After quality appraisal and synthesis of the evidence we were unable to make a conclusion as to the effectiveness of magnesium for RLS/PLMD. It is not clear whether magnesium helps relieve RLS or PLMD or in which patient groups any benefit might be seen.

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.

Short-term hypoxia reduces arterial stiffness in healthy men.

This study examined the effects of hypoxia (80% arterial oxyhaemoglobin saturation for 20 min) and the accompanying changes in heart rate and blood pressure on two components of arterial stiffness in healthy men. Augmentation index (AIx) and time to reflection (Tr) representing measures of muscular artery and aortic stiffness, respectively, were continuously measured. At first, subjects were exposed to either hypoxia (n = 12) or room air (n = 5). During early hypoxia AIx increased by 6% before decreasing to baseline. After hypoxia AIx decreased by a further 6%. In contrast there was no change in Tr. Six subjects were then exposed to hypoxia following infusion with the nitric oxide (NO) synthase inhibitor NG-mono-methyl-L: -arginine (L-NMMA) or saline. During hypoxia AIx decreased by 12% following saline but increased by 14% after L-NMMA and Tr did not change. These findings suggest that hypoxia may induce NO-mediated vasodilatation of small muscular arteries but not the aorta.

Improved outcomes of patients with cystic fibrosis admitted to the intensive care unit.

BACKGROUND: Invasive mechanical ventilation (IMV) has been previously associated with a poor outcome for patients with cystic fibrosis (CF), but with improved survival and the availability of lung transplantation intensive care unit (ICU) admission is being increasingly considered. This study aimed to review the outcomes of adult CF patients admitted to ICU, and to identify factors that may have influenced outcomes. METHODS: A retrospective audit was conducted of CF patients admitted to ICU. Anthropometric data, spirometry, nutritional status, sputum microbiology, arterial blood gas tensions, and mode of ventilation used were recorded. Immediate and 1-year survival and lung transplantation utilisation were recorded. RESULTS: Twenty patients were admitted to ICU and nine (45%) survived to hospital discharge. Five of the nine survivors had potentially reversible conditions. Four patients admitted with respiratory exacerbations alone who survived, were maintained on non-invasive ventilation (NIV). The relative risk of deaths for patients with a BMI < 18 and a FEV1 < 24% predicted were 3.25 (1.27-3.25), and 3.68 (1.11-16.33), respectively. CONCLUSIONS: The outcome of patients with CF admitted to ICU has improved, with 45% of the patients in this study surviving to hospital discharge. Five of these survivors underwent successful lung transplantation. Long-term use of NIV post discharge may have contributed to this favourable outcome. A BMI < 18 and FEV1 < 24% predicted were associated with a significantly higher relative risk of death.