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Obstructive sleep apnoea (OSA) was traditionally thought to be mainly caused by obesity and upper airway crowding, and hence OSA management was not personalised according to particular characteristics, with most symptomatic patients receiving continuous positive airway pressure therapy. Recent advances in our understanding have identified additional potential and distinct causes of OSA (endotypes), and subgroups of patients (phenotypes) with increased risk of cardiovascular complications. In this review, we discuss the evidence to date as to whether there are distinct clinically useful endotypes and phenotypes of OSA, and the challenges to the field in moving towards delivering personalised therapy in OSA.

The SARS-CoV-2 can lead to severe illness with COVID-19. Outcomes of patients requiring mechanical ventilation are poor. Awake proning in COVID-19 improves oxygenation, but on data clinical outcomes is limited. This single-centre retrospective study aimed to assess whether successful awake proning of patients with COVID-19, requiring respiratory support (continuous positive airways pressure (CPAP) or high-flow nasal oxygen (HFNO)) on a respiratory high-dependency unit (HDU), is associated with improved outcomes. HDU care included awake proning by respiratory physiotherapists. Of 565 patients admitted with COVID-19, 71 (12.6%) were managed on the respiratory HDU, with 48 of these (67.6%) requiring respiratory support. Patients managed with CPAP alone 22/48 (45.8%) were significantly less likely to die than patients who required transfer onto HFNO 26/48 (54.2%): CPAP mortality 36.4%; HFNO mortality 69.2%, (p=0.023); however, multivariate analysis demonstrated that increasing age and the inability to awake prone were the only independent predictors of COVID-19 mortality. The mortality of patients with COVID-19 requiring respiratory support is considerable. Data from our cohort managed on HDU show that CPAP and awake proning are possible in a selected population of COVID-19, and may be useful. Further prospective studies are required.

The effect of continuous positive airway pressure (CPAP) on cardiovascular events is uncertain in minimally symptomatic obstructive sleep apnoea. Previous 2-year follow-up data from the Multicentre Obstructive Sleep Apnoea Intervention Cardiovascular (MOSAIC) trial showed a marginal reduction in cardiovascular events with CPAP therapy. We now present long-term MOSAIC study follow-up data. Median (first quartile, third quartile) follow-up was 5.0 (2.2, 5.0) and 3.7 (1.5, 5.0) years for CPAP and standard care, respectively. Compared to standard care, CPAP had no statistically significant effect on the risk of cardiovascular events (HR=0.83, p=0.54, 95% CI 0.46–1.51).

Introduction Positional treatments have a long history of usage in obstructive sleep apnoea (OSA). Recent developments of more sophisticated therapies reported good response in patients with an AHI of 1,2 We hypothesised that patients with mild to moderate OSA usually have periods both with and without OSA, and that the OSA periods will be mainly due to supine OSA. Such patients might therefore be trialled on positional therapies without specific assessment of posture. Methods Patients included had OSA and underwent an in-hospital respiratory sleep study between May- July 2016. Sleep studies included video review for identification of supine sleep. The oxygen desaturation index >4% (ODI) was recorded in supine and non-supine positions. The ratio of the total to non-supine ODI was calculated. Results 40 patients’ sleep studies were suitable for analysis. 7 patients were excluded: 3 due to comorbidities (hypoventilation/CSA), 3 due to lack of supine sleep ( 2 (SD 9.0). The median supine ODI was significantly higher than the median total ODI (supine ODI 54.3/h, IQR 47.9; total ODI 28.6/h, IQR 34.4; p Discussion Our data suggests that patients with lower ODIs are more likely to have supine predominant OSA. At ODI values over 40 it is very unlikely that there is a posturally dependant component to a patient’s OSA. However, the reverse is not the case; although many patients with low ODIs do have a postural component, many do not. It is therefore necessary to objectively assess the degree of supine predominant OSA in future trials of positional therapies, but patients with ODIs over 40 could be excluded at the outset. References Levendowski DJ, et al . Assessment of a neck-based treatment and monitoring device for positional obstructive sleep apnea. J Clin Sleep Med 2014; 10 (8):863–71. Levendowski DJ, et al . Capability of a neck worn device to measure sleep/wake, airway position, and differentiate benign snoring from obstructive sleep apnea. J Clin Monit Comput 2015; 29 :53–64.

Background Anaesthesia worsens OSA, and may lead to respiratory and cardiac complications. Three critical incidents have occurred in the Oxford Hospitals in recent years. OSA is very common at around 5–25%, but half the cases are not diagnosed. So should we screen for OSA pre-operatively? Audit Over 9 months from July 2015 all patients completed a STOP-BANG questionnaire in a gynaecology pre-operative clinic. Those with snoring and a score of 3 or greater were referred for a sleep study. Data is presented for 102 patients (100 female; 2 transgender) with a mean ± SD age of 55.7 ± 11.4 yrs, BMI 35.8 ± 7.6 kg/m2 and collar size 40.0 ± 4.8 cm. The rate of non-attendance was high at 19/102 (19%), with those with a lower STOP-BANG score being more likely not to attend. Of those undergoing a sleep study, a new diagnosis was made in 53/83 (52%) patients. Symptoms and OSA/hypoventilation were sufficient for CPAP to be started in 23 patients and NIV in 1 (29% of those screened), with positive diagnoses more likely with higher STOP-BANG scores. The median (IQR) time to CPAP set-up was 80 (52, 100) days, thus a substantial proportion of patients had surgery before treatment. How should we ensure anaesthetic safety for patients at risk of OSA? Completing a sleep study and establishing OSA patients on CPAP prior to surgery would significantly slow the surgical pathway, and there is no evidence that this would improve outcome. However it seems sensible for anaesthesia of all patients deemed at risk of OSA (STOP-BANG 3+) to be managed with special precautions. We pragmatically recommend that all patients found to have a STOP-BANG score of 5+ or strong clinical suspicion of OSA, who are undergoing major surgery AND in whom it is reasonable to delay surgery, are referred for a sleep study prior to surgery. Patients with a STOP-BANG of 3+ not falling into this category should be informed they are at risk of OSA, and advised to seek a referral from their GP to the sleep clinic if they find symptoms of sleepiness troublesome.

Introduction Severity of OSA and early patterns of CPAP usage have previously been shown to determine subsequent long term CPAP use in patients with symptomatic moderate-to-severe disease. 1 We wished to see if different factors influenced compliance in minimally symptomatic patients. Methods Patients were randomised to 6-months of CPAP or standard care if they had an ODI of >7.5 h due to OSA on a baseline sleep study, but had insufficient daytime OSA symptoms to mandate CPAP. 2 Baseline characteristics (Table 1), medical history, ESS, SAQLI and SF-36 were recorded. Repeat overnight pulse oximetry was performed after entry for uniformity of trial ODI across recruiting centres. CPAP usage data were downloaded at the 2–4 week assessment, and at the 6 month assessment. Those who withdrew were assumed to have 0:00 h/n usage. Correlations were calculated between CPAP usage at the 6 month assessment and both the baseline characteristics and to the 2–4 week CPAP usage data. Results Median CPAP usage at 2–4 week follow-up was low at 2:49 h/n (n = 174, IQR 0:44, 5:13). Median usage at 6 month follow-up was 2:17 h/n (n = 195, IQR 0:08, 4:54). At 6 months males had significantly greater mean usage at 2:56 h/n compared to 1:47 h/n in females (95% confidence intervals of the difference, -1:49 to -0:09 h/n, p = 0.02). There were no other significant predictors of 6 month usage (age, BMI, ODI, ESS, sleep symptoms, smoking status, ethnicity, SAQLI, SF-36). Average usage of CPAP at 2–4 week assessment was moderately correlated with the average usage at the 6 month assessment (r = 0.76, p Conclusions Male gender predicted greater CPAP usage at 6 months, but no other baseline characteristics were predictive of CPAP usage in these minimally symptomatic patients with generally mild OSA. 2–4 week CPAP usage was predictive of 6 month usage, but by no means could all patients’ usage be predicted at such an early stage. Thus in clinical practice, trials of CPAP are necessary in patients with minimally symptomatic OSA but it may be necessary for patients to try CPAP for longer than one month to determine those benefitting from treatment in the long term. References 1 Thorax 2010; 65 :829–32 2 Thorax 2012; 67 :1090-66

The Multicentre Obstructive Sleep Apnoea Intervention Cardiovascular (MOSAIC) trial investigated the effect of continuous positive airway pressure (CPAP) on both sleepiness and predicted cardiovascular risk over 6 months in minimally symptomatic patients with obstructive sleep apnoea. Although there was clear benefit in terms of Epworth Sleepiness Score, there was no improvement in blood pressure and predicted vascular risk score. In order to calculate the required size of future trials, with real vascular events as the endpoint, the rate of such events in this population is needed. 188 patients from the original trial were followed for 2 years. The overall number of new vascular events over the 2 years was 25, and all-cause mortality was 4. There was a weak statistically significant reduction in vascular events in the CPAP group (p=0.049). Large-scale randomised trials are needed to determine if CPAP causes a real reduction in vascular events in minimally symptomatic patients. Based on our figures, future trials of CPAP versus no treatment would need to randomise approximately 2540 patients to not miss a real reduction in vascular events and over 6000 for mortality.

Introduction The MOSAIC multicentre trial investigated the effect of CPAP versus no CPAP on both sleepiness and a vascular risk score, over 6 months, in nearly 400 minimally symptomatic patients with OSA. The results on the vascular risk score, reported previously, suggested no potential vascular benefit of CPAP, although endothelial function improved. The incidence of real events is needed to calculate the size of any future trials in this group of patients. Methods We have followed the Oxford cohort of 189 patients for two years to assess real vascular event rates and the incidence of accidents and hospital admissions. The events have been verified by inspection of hospital notes and phone calls to patients. The CPAP/No CPAP allocation was based on intention to treat. At the end of the original 6 month trial, 71% of patients, initially randomised to CPAP, stated an intention to continue CPAP. Results The table shows the 2 year incidence of accidents at home, work and driving (66/189), the incidence of new vascular events (25/189), and all cause mortality (4/189). Conclusions The event rates are moderate, and there is no statistically significant difference between the groups. A power calculation, based on these figures, suggests that in order not to miss a 30% reduction in relative risk over 2 years (4% absolute reduction), with 90% power, would require 2,540 patients randomised; for accidents, 880; for mortality over 6,000.

Ganfort eye drops are indicated for adult patients with open-angle glaucoma who have poor response to topical β-blockers or prostaglandin analogues. They contain 0.3 mg of bimatoprost (a prostaglandin) and 5 mg of timolol (β-blocker). The authors present a case of a 45-year-old man with glaucoma presenting with shortness of breath. On admission, he had a normal heart rate, pulse oximetry and examination. Despite being of low risk stratification using the Wells score and the Modified Geneva Score for pulmonary emboli, CT pulmonary angiogram scan subsequently showed extensive bilateral multiple large pulmonary emboli. This case demonstrates that the systemic absorption of ocular β blockers is extremely high and it bypasses the first pass metabolism. Therefore, even one drop of Ganfort into each eye once a day was sufficient to disguise the tachycardia of a large pulmonary emboli.