Jenny Ngai

Nasal CPAP reduces systemic blood pressure in patients with obstructive sleep apnoea and mild sleepiness

Background: A randomised controlled study was undertaken to examine the effect of nasal continuous positive airway pressure (CPAP) on 24 hour systemic blood pressure (BP) in patients with obstructive sleep apnoea (OSA). Methods: Patients were fitted with an ambulatory BP measuring device as outpatients during normal activities and recorded for 24 hours before starting therapeutic or subtherapeutic (4 cm H2O) CPAP treatment. BP monitoring was repeated before completion of 12 weeks of treatment. The primary end point was the change in 24 hour mean BP. Results: Twenty three of 28 participants in each treatment arm completed the study. There was no significant difference between the two groups in age, body mass index, Epworth Sleepiness Score, apnoea-hypopnoea index, arousal index, and minimum Sao2. Twenty four patients were hypertensive. The pressure in the therapeutic CPAP group was 10.7 (0.4) cm H2O. CPAP usage was 5.1 (0.4) and 2.6 (0.4) hours/night for the therapeutic and subtherapeutic CPAP groups, respectively (p<0.001). After 12 weeks of treatment there were significant differences between the two CPAP groups in mean (SE) changes in 24 hour diastolic BP (−2.4 (1.2) v 1.1 (1.0) mm Hg (95% CI −6.6 to −0.5), p = 0.025); 24 hour mean BP (−2.5 (1.3) v 1.3 (1.1) mm Hg (95% CI −7.2 to −0.2), p = 0.037); sleep time systolic BP (−4.1 (2.1) v 2.2 (1.8) mm Hg (95% CI −11.8 to −0.7), p = 0.028); and sleep time mean BP (−3.6 (1.7) v 1.3 (1.4) mm Hg (95% CI −9.2 to −0.4), p = 0.033). Conclusions: Compared with subtherapeutic CPAP, 12 weeks of treatment with therapeutic CPAP leads to reductions in 24 hour mean and diastolic BP by 3.8 mm Hg and 3.5 mm Hg, respectively, in mildly sleepy patients with OSA.

Validation of Embletta portable diagnostic system for identifying patients with suspected obstructive sleep apnoea syndrome (OSAS)

Background and objectives:  This study aimed to evaluate the diagnostic accuracy of Embletta portable diagnostic system (PDS, Medcare, Reykjavik, Iceland) for the screening of sleep apnoea in clinical practice.

Effect of early pulmonary rehabilitation on health care utilization and health status in patients hospitalized with acute exacerbations of COPD.

Background and objective:  Acute exacerbations of chronic obstructive pulmonary disease (AECOPD) incur heavy utilization of health‐care resources for patients who require hospitalization. We evaluated whether an early outpatient pulmonary rehabilitation programme (PRP) after hospitalization for AECOPD could reduce acute health‐care utilization over the succeeding year.

A prospective cohort study of the long-term effects of CPAP on carotid artery intima-media thickness in Obstructive sleep apnea syndrome

ObjectiveTo examine the long-term effect of CPAP on carotid artery intima-media thickness (IMT) in patients with Obstructive sleep apnea syndrome(OSAS).MethodsA prospective observational study over 12 months at a teaching hospital on 50 patients newly diagnosed with OSAS who received CPAP or conservative treatment (CT). Carotid IMT was assessed with B-mode Doppler ultrasound from both carotid arteries using images of the far wall of the distal 10 mm of the common carotid arteries at baseline, 6 months and 12 months.Measurements and results [mean (SE)]Altogether 28 and 22 patients received CPAP and CT respectively without significant differences in age 48.8(1.8) vs 50.5(2.0)yrs, BMI 28.2(0.7) vs 28.0(1.2)kg/m2, ESS 13.1(0.7) vs 12.7(0.6), AHI 38(3) vs 39(3)/hr, arousal index 29(2) vs 29(2)/hr, minimum SaO2 75(2) vs 77(2)% and existing co-morbidities. CPAP usage was 4.6(0.3) and 4.7(0.4)hrs/night over 6 months and 1 year respectively. Carotid artery IMT at baseline, 6 months, and 12 months were 758(30), 721(20), and 705(20)micron for the CPAP group versus 760(30), 770(30), and 778(30)micron respectively for the CT group, p = 0.002.Among those free of cardiovascular disease(n = 24), the carotid artery IMT at baseline, 6 months and 12 months were 722(40), 691(40), and 659(30)micron for the CPAP group (n = 12) with usage 4.5(0.7) and 4.7(0.7) hrs/night over 6 months and 12 months whereas the IMT data for the CT group(n = 12) were 660(20), 685(10), and 690(20)micron respectively, p = 0.006.ConclusionsReduction of carotid artery IMT occurred mostly in the first 6 months and was sustained at 12 months in patients with reasonable CPAP compliance.

Sleep‐disordered breathing and continuous positive airway pressure compliance in a group of commercial bus drivers in Hong Kong

Objective and background:  Sleep‐disordered breathing may predispose drivers to road traffic accidents. However, CPAP acceptance and compliance among commercial bus drivers is unknown.

A longitudinal study of serial BODE indices in predicting mortality and readmissions for COPD

INTRODUCTION BODE index comprises Body mass index, Obstruction of the airway [FEV(1)], Dyspnoea score [modified Medical Research Council questionnaire] and Exercise capacity [6 min walk test]. This study assessed the role of serial changes in BODE index in predicting mortality and readmissions of COPD patients. METHODS A prospective cohort study involving 243(208 males) COPD patients hospitalized for acute exacerbations of COPD [AECOPD]. BODE index was assessed at 6 weeks(baseline), 6, 12, 18 and 24 months post hospital discharge. Mortality and readmissions in the subsequent 3 years were recorded. All the patients were managed by usual care without additional intervention. RESULTS The mean (SD) age and FEV(1)% predicted were 74.2(7.8) yrs and 51.7(21.6)% respectively. Over the 3 years, 25.1% died whereas 76.5% had at least 1 readmission for AECOPD. Baseline BODE index was predictive of both the survival and readmissions to hospital for AECOPD by Cox regression analysis (p < 0.001 for both survival and readmissions). Over 24 months, 71(40.1%), 94(53.1%), 12(6.8%) patients had increased (>1 point), no change, and decreased in BODE (>1 point) index respectively. Serial changes in BODE index at 6 month was marginally associated with mortality, but not at 12-, 18- and 24-month. The 6-, 12- and 24-month BODE indices were predictive of the readmissions for AECOPD when compared to baseline. CONCLUSION Baseline BODE index could predict both survival and readmissions for AECOPD, whereas serial BODE indices were not predictive of survival at 3 years. Single rather than serial measurements of BODE index is sufficient for prediction of survival and readmissions for patients treated with usual care.

Measurement of tumor necrosis factor-α, leukotriene B4, and interleukin 8 in the exhaled breath condensate in patients with acute exacerbations of chronic obstructive pulmonary disease

Background Assessment of airway inflammation in the clinical course of acute exacerbations of chronic obstructive pulmonary disease (AECOPD) may advance our understanding of the pathogenesis and treatment. Objectives To assess airway inflammation in patients during the course of AECOPD by serial analyses of their exhaled breath condensates (EBC). Methods Twenty-six patients with AECOPD (22 males, mean[SD] percentage predicted forced expiratory volume in one second (FEV1) 44.8 [14.3]), 11 with stable COPD, and 14 age and sex-matched healthy controls were studied. Patients with AECOPD were treated with systemic steroid and antibiotic for 7 days. EBC was collected from each patient with AECOPD on Day 5, 14, 30, and 60 post-hospitalization using EcoScreen (VIASYS Healthcare, USA) during tidal breathing over 10 minutes. Concentrations of tumor necrosis factor-α (TNF-α), leukotriene B4 (LTB4), and interleukin-8 (IL-8) were measured by enzyme-linked immunosorbent assay. Results The median (IQR) of TNF-α level on Day 5 was 5.08 (3.80–6.32) pg/ml, which was lower than on Day 14 (5.84 [4.91–9.14] pg/ml, p = 0.017), Day 30 (6.14 [3.82–7.67] pg/ml, p = 0.045), and Day 60 (5.60 [4.53–8.80] pg/ml, p = 0.009). On Day 60, subjects receiving inhaled corticosteroid (ICS) had a lower level of TNF-α than those who were not (4.82 [4.06–5.65] vs 7.66 [5.48–10.9] pg/ml, p = 0.02). EBC LTB4 level did not change significantly during recovery from AECOPD whereas IL-8 was mostly undetectable. Conclusions EBC TNF-α level was low in patients receiving systemic steroid and antibiotic therapy for AECOPD. These findings suggest a potential role for serial EBC TNF-α for non-invasive monitoring of disease activity.

Validation study of a portable monitoring device for identifying OSA in a symptomatic patient population.

Background and objective:  Obstructive sleep apnoea syndrome (OSAS) is a common disorder associated with early atherosclerosis, diabetes mellitus, ischaemic heart disease and cerebrovascular disease. The gold standard for confirming OSAS is based on an attended overnight polysomnography (PSG) in a sleep laboratory; however lack of health‐care resources creates long waiting times for patient access to this diagnostic test. This study evaluated the ability of a portable sleep‐monitoring device to identify patients in Hong Kong with suspected OSAS.

A Randomized Controlled Study to Examine the Effect of a Lifestyle Modification Program in OSA

BACKGROUND Obesity is an important risk factor for OSA. This study aimed to assess the effect of weight reduction through a lifestyle modification program (LMP) on patients with moderate to severe OSA. METHODS This was a parallel group, randomized controlled trial. Altogether, 104 patients with moderate to severe OSA diagnosed on portable home sleep monitoring were randomized to receive a dietician-led LMP or usual care for 12 months. The primary outcome was reduction of apnea-hypopnea index (AHI) at 12 months as assessed by portable home sleep monitoring. RESULTS In the intention-to-treat analysis (ITT), LMP (n = 61) was more effective in reducing AHI from baseline (16.9% fewer events in the LMP group vs 0.6% more events in the control group, P = .011). LMP was more effective in reducing BMI (-1.8 kg/m2, 6.0% of the initial BMI; -0.6 kg/m2, 2.0% of the initial BMI in control group; P < .001). The reduction in daytime sleepiness as assessed by Epworth Sleepiness Scale was not significant in ITT but was more in the LMP group (-3.5 in the LMP group vs -1.1 in the control group, P = .004) by treatment per protocol analysis. There was modest improvement in mental health in the Short Form Health Survey. Eating behavior was improved with increased intake of protein and fiber. These changes were observed 4 months after the initial intensive diet counseling and persisted at 12 months. CONCLUSIONS LMP was effective in reducing the severity of OSA and daytime sleepiness. The beneficial effect was sustained in 12 months. TRIAL REGISTRY ClinicalTrials.gov; No.: NCT01384760; URL: www.clinicaltrials.gov.

Mesenteric fat thickness is associated with increased risk of obstructive sleep apnoea

Mesenteric fat is a type of intraperitoneal adipose tissue draining into portal circulation. The objective of this study was to investigate the relationships between mesenteric fat thickness and obstructive sleep apnoea (OSA) in patients with suspected OSA.