Comparison of conventional nighttime with automatic or manual daytime CPAP titration in unselected sleep apnea patients: study of the usefulness of daytime titration studies

Daytime CPAP titration studies with full polysomnography have been successfully performed in patients with severe sleep apnea-hypopnea syndrome (SAHS). The implementation of daytime studies in unselected SAHS patients could help to reduce the waiting lists for CPAP titrations. The main purpose of this study was to compare the effectiveness of conventional versus manual or automatic daytime CPAP titration in unselected patients with SAHS. Ninety-three consecutive patients with SAHS in whom CPAP was indicated were assigned to conventional titration or to manual or automatic (AutoSet) daytime CPAP titration, after sleep deprivation. The number of valid studies, sleep architecture, final pressure selected and mean pressure in the different sleep stages were compared. Changes in sleepiness (Epworth sleepiness score) and hours of CPAP use were assessed after 3 months of treatment. Four patients did not sleep (3 AutoSet, 1 conventional daytime groups). Sleep latency was shorter during automatic daytime titration whereas REM latency was shorter in daytime studies; the percentage of sleep stages was similar during all types of titration. CPAP requirements were significantly higher during REM sleep in conventional and manual daytime titrations while mean pressure was unchanged throughout sleep stages during AutoSet titration. CPAP pressure selected with conventional or daytime manual titration (7.5(2.2) cm H2O and 7.4(1.5) cm H2O, ns) were significantly lower (P< 0.001) than with AutoSet (9.4(1.6) cm H20. All groups showed similar decrease of sleepiness and hours of use of CPAP at 3 months of follow-up. Automatic and manual daytime PSG studies after sleep deprivation are useful for CPAP titration in unselected patients with SAHS. Pressure selected with AutoSet is significantly higher than with conventional daytime or nighttime titration, although not significant in terms of treatment compliance and symptom improvement.     

Response of automatic continuous positive airway pressure devices to different sleep breathing patterns: a bench study

Evaluating the usefulness of automatic continuous positive airway pressure (CPAP) in treating the sleep apnea-hypopnea syndrome (SAHS) is not easy because the algorithms for automatic CPAP implemented in the devices available are not well known and are probably dependent on the device. In addition, at present it is not possible to test the behavior of automatic CPAP devices in response to well-defined breathing patterns. Our aim was to implement a bench test to characterize the responses of automatic CPAP devices by subjecting them to breathing patterns of patients with SAHS. To this end, a variety of typical breathing patterns (normal, apneas, hypopneas, flow limitation, snoring) previously recorded in patients with SAHS during sleep were reproduced by a breathing waveform generator. Five commercially available automatic CPAP devices were tested. The responses of the devices to apneas, hypopneas, flow limitation, and snoring were considerably different. In some devices, the response was modified by air leaks similar to the ones found in patients. Consequently, the effectiveness of automatic CPAP assessed in clinical tests performed by using particular devices has no general validity. Testing automatic CPAP devices in a bench study is a useful first step in evaluating the performance of this new type of device in adjusting nasal pressure for each patient.     

Effect of compliance to continuous positive airway pressure on exacerbations,lung function and symptoms in patients with chronic obstructive pulmonary disease and obstructive sleep apnea (overlap syndrome)

Introduction

Patients with overlap syndrome (OS), that is obstructive sleep apnea (OSA) and chronic obstructive pulmonary disease (COPD), are at increased risk of acute exacerbations related to COPD (AECOPD). We assessed the effect of CPAP compliance on AECOPD, symptoms and pulmonary function in OS patients.

Methods

Consecutive OS patients underwent assessment at baseline and at 12 months under treatment with CPAP of: AECOPD and hospitalizations, COPD Assessment Test (CAT) and modified British Medical Research Council (mMRC) questionnaires, pulmonary function testing and 6-min walking test (6MWT).

Results

In total, 59 patients (54 males) with OS were followed for 12 months and divided post hoc according to CPAP compliance into: group A with good (≥4 h CPAP use/night, n = 29) and group B with poor (<4 h CPAP use/night, n = 30) CPAP compliance. At 12 months, group A showed improvements in FEV₁ (p = 0.024), total lung capacity (p = 0.024), RV/TLC (p = 0.003), 6MWT (p < 0.001) and CAT (p < 0.001). COPD exacerbations decreased in patients with good CPAP compliance from baseline to 12 months (17 before vs. 5 after, p = 0.001), but not in those with poor compliance (15 before vs. 15 after, p = 1). At multivariate regression analysis, COPD exacerbations were associated with poor CPAP compliance (β = 0.362, 95% CI: 0.075–0.649, p = 0.015).

Conclusions

When compared to poorly compliant patients, OS patients with good CPAP compliance had a lower number of AECOPD and showed improved lung function and COPD related symptoms.     

Improving Heart Rate Variability in Sleep Apnea Patients: Differences in Treatment with Auto-titrating Positive Airway Pressure (APAP) Versus Conventional CPAP

The effect of positive airway pressure treatments in different modalities on the cardiovascular consequences of the disease in sleep apnea patients is still unclear. We aimed to compare auto-titrating positive airway pressure (APAP) and conventional continuous positive airway pressure (CPAP) in terms of improving heart rate variability (HRV) in obstructive sleep apnea patients. This was a prospective study done in a tertiary research hospital. All patients underwent a manual CPAP titration procedure to determine the optimal pressure that abolishes abnormal respiratory events. Then patients underwent two treatment nights, one under APAP mode and one under conventional CPAP mode with a 1-week interval. Forty newly diagnosed obstructive sleep apnea patients were enrolled in the study. We compared heart rate variability analysis parameters between the APAP night and the CPAP night. This final analysis included the data of 28 patients (M/F: 22/6; mean age = 46 ± 10 years). Sleep characteristics were comparable between the two treatment nights, whereas all-night time domains of HRV analysis such as HF, nuLF, and LF/HF were different between APAP and CPAP nights (2.93 ± 0.31 vs. 3.01 ± 0.31; P = 0.041; 0.75 ± 0.13 vs. 0.71 ± 0.14; P = 0.027; and 4.37 ± 3.24 vs. 3.56 ± 2.07; P = 0.023, respectively). HRV analysis for individual sleep stages showed that Stage 2 LF, nuLF, nuHF, LF/HF parameters entirely improved under CPAP treatment whereas APAP treatment resulted in nonsignificant changes. These results suggest that despite comparable improvement in abnormal respiratory events with APAP or CPAP treatments, CPAP may be superior to APAP in terms of correcting cardiovascular alterations in sleep apnea patients.     

The Effect of Continuous Positive Airway Pressure on Stair-Climbing Performance in Severe COPD Patients

Abstract

Stair climbing is associated with dynamic pulmonary hyperinflation and the development of severe dyspnea in patients with chronic obstructive pulmonary disease (COPD). This study aimed to assess whether (i) continuous positive airway pressure (CPAP) applied during stair climbing prevents dynamic hyperinflation and thereby reduces exercise-induced dyspnea in oxygen-dependent COPD-patients, and (ii) the CPAP-device and oxygen tank can be carried in a hip belt. In a randomised cross-over design, oxygen-dependent COPD patients performed two stair-climbing tests (44 steps): with supplemental oxygen only, then with the addition of CPAP (7 mbar). The oxygen tank and CPAP-device were carried in a hip belt during both trials.

Eighteen COPD patients were included in the study. Although all patients could tolerate stair climbing with oxygen alone, 4 patients were unable to perform stair climbing while using CPAP. Fourteen COPD patients (mean FEV₁ 36 ± 14% pred.) completed the trial and were analyzed. The mean flow rate of supplemental oxygen was 3 ± 2 l/min during stair climbing. Lung hyperinflation, deoxygenation, hypoventilation, blood lactate production, dyspnea and the time needed to manage stair climbing were not improved by the application of CPAP (all p > 0.05). However, in comparison to climbing with oxygen alone, limb discomfort was reduced when oxygen was supplemented with CPAP (p = 0.008).

In conclusion, very severe COPD patients are able to carry supporting devices such as oxygen tanks or CPAP-devices in a hip belt during stair climbing. However, the application of CPAP in addition to supplemental oxygen during stair climbing prevents neither exercise-induced dynamic hyperinflation, nor dyspnea.     

慢性阻塞性肺疾病患者睡眠呼吸紊乱类型及其与呼吸中枢反应性的关系

目的分析重叠综合征[慢性阻塞性肺疾病（COPD）合并睡眠呼吸暂停低通气综合征（SAHS）]患者睡眠呼吸紊乱的特点，并探讨其与呼吸中枢反应性的关系。方法对300例稳定期COPD患者经问卷、Epworth嗜睡量表及家庭血氧饱和度监测，对氧减饱和指数〉5次／h或嗜睡评分≥10分的患者进行多导生理记录仪睡眠呼吸监测，其中呼吸暂停低通气指数（AHI）≥10次／h的患者有79例（重叠综合征组）。选择年龄、性别及体重指数与其相匹配的118例单纯SAHS患者（SAHS组），对比分析其睡眠呼吸紊乱的特点。另外测定重叠综合征组22例患者的呼吸中枢高CO2反应性和低氧反应性，并与300例COPD患者中17例和SAILS组中17例的相应检测结果进行比较。结果40％（32／79）的重叠综合征患者在睡眠过程中出现延续时间〉1min的持续肺泡通气不足，但单纯SAHS患者此种现象很少见。重叠综合征组的低通气指数占AHI百分比[（69±30）％]、总低通气时间占总睡眠时间百分比[（15±12）％]均较单纯SAHS组[（52±31）％、（12±10）％]明显增高。重叠综合征患者在清醒状态下的△呼气流量／△动脉血氧饱和度[（-0．11±0．05）L·min^-1·％^-1]和△呼气流量／△动脉血二氧化碳分压[（1．1±0．8）L·min^-1·mmHg^-1（1mmHg=0．133kPa）]均明显低于单纯SAHS患者[（-0．35±0．24）L·min^-1·％^-1和（1．6±0．8）L·min^-1·mmHg^-1]。结论重叠综合征患者的睡眠呼吸紊乱模式以低通气为主，其清醒时呼吸中枢的低氧反应性降低。     

TLR4 Up-regulation and Reduced Foxp3 Expression in Mechanically Ventilated Smokers with Obstructive Chronic Bronchitis

Abstract

Background: Chronic bronchitis (CB) is a risk factor in chronic obstructive pulmonary disease (COPD) for accelerated lung function decline and increased mortality. The lung and systemic inflammatory and immunological profile of COPD patients with CB which acutely experience respiratory failure upon a disease exacerbation is unknown. Methods: In this study, we explored the expression of Foxp3 by western blot analysis, TLR4 by immunocytochemistry and the concentrations of IP-10 and IL-8 by ELISA in the mini-bronchoalveolar lavages (mini-BAL) and in the peripheral blood of patients with respiratory failure requiring intubation and mechanical ventilation. The recruited subjects were separated into three different groups: smokers with CB and COPD (COPD, n = 18), smokers with CB but without COPD (S, n = 8) and patients without CB and without COPD (C, n = 10). Results: In mini-BAL of COPD group, Foxp3 and IP-10 were significantly reduced while TLR4 was significantly increased in comparison to C. TLR4 was also increased in mini-BAL of S. In COPD peripheral blood, Foxp3 was reduced in comparison to C but no significant differences were observed for TLR4 and for IP-10. No significant differences were observed for IL-8 concentrations in the mini-BAL and in the blood of the recruited patients. The mini-BAL TLR4 expression correlated with the Clinical Infective Pulmonary Score. Conclusions: In exacerbated COPD patients with respiratory failure, lung and systemic reduced immune regulatory events (low Foxp3 expression) and lung increased innate immunity responses (high TLR4 expression) occur. These events may contribute to the increased inflammatory events leading to respiratory failure.     

Performance of nasal prongs in sleep studies : spectrum of flow-related events

OBJECTIVES: The use of nasal prongs connected to a pressure transducer is a noninvasive, sensitive method to detect respiratory events, and can be easily implemented in routine sleep studies. Moreover, its good time response allows the detection of several flow-related phenomena of high interest, in addition to apnea and hypopnea. The aims of the study were to examine the quality and performance of the nasal prong flow signal, and to describe other flow-related events during full-night polysomnography studies. METHODS: Twenty-seven subjects were studied (16 male subjects; mean +/- SD age, 49 +/- 14 years; mean body mass index, 27 +/- 4 kg/m(2)): 15 subjects recruited from the general population and 12 consecutive patients with suspected sleep apnea/hypopnea syndrome (SAHS). RESULTS: A blind analysis of the respiratory events detected both by nasal prongs and thermistor was done. The quality of the nasal prong signal recordings was considered optimal for scoring purposes in 78% of cases, and no recording was considered uninterpretable. The nasal prong signal detected additional flow-related events not observed by the thermistor: (1) short and long (> 2 min) periods of inspiratory flow limitation morphology without decrease in the amplitude of the signal; (2) periods of mouth expiration; and (3) snoring. The apnea/hypopnea index was significantly higher with the nasal prong scoring (18 vs 11 [p < 0.05] in the general population and 37 vs 27 [p < 0.001] in the group with suspected SAHS). CONCLUSIONS: The incorporation of nasal prongs in routine full-night studies is an attainable technical option that provides adequate recordings in most cases. Additionally, relevant information not scored by thermistors is obtained on flow-related respiratory events, thus increasing diagnostic accuracy.     

Lack of Benefit of Continuous Positive Airway Pressure on Lung Function in Patients with Overlap Syndrome

Obstructive sleep apnea (OSA) has been shown to be an inflammatory stimulus and may potentially result in a deterioration in the respiratory status of patients with coexistent chronic obstructive pulmonary disease (COPD) (overlap syndrome). We hypothesized that with treatment of OSA, there would be an improvement in coexistent COPD in overlap patients. We also sought to characterize overlap patients by comparing them with patients with either OSA or COPD alone. We performed a retrospective study of patients who attended a university-affiliated Veterans Affairs hospital. Demographic and clinical data were obtained from the medical charts and pharmacy records for the preceding two years and for the two years following the initiation of continuous positive airway pressure (CPAP) therapy. Overlap patients had moderately severe sleep apnea (AHI 28.6 ± 4.2) and moderately severe COPD (FEV₁= 1.94 ± 0.10 L). The prevalence of overlap syndrome in COPD patients was 11.9%, and 41% in OSA patients. Overlap patients who were compliant with CPAP therapy experienced a greater decrease in FEV₁, percent predicted FEV₁, percent decrease in FEV₁, FVC, percent predicted FVC, and percent decrease in FVC when compared with noncompliant patients. A very strong correlation was found between the average hours of CPAP use per day and the percent decrease in FEV₁ (r = 0.69, p = 0.003). There was a similar strong correlation for the decrease in FEV₁ and percent predicted FEV₁. OSA is common in COPD patients; similarly, COPD is common in OSA patients. Treatment of OSA with CPAP therapy in patients with overlap syndrome may not lead to an improvement in the coexistent COPD.     

Effectiveness of continuous positive airway pressure in mild sleep apnea-hypopnea syndrome

The aim of this trial was to evaluate the effectiveness of continuous positive airway pressure (CPAP) in patients with mild sleep apnea- hypopnea syndrome (SAHS). One hundred forty-two consecutive patients with mild SAHS (apnea-hypopnea index 10-30, without severe sleepiness) were randomly assigned to receive conservative treatment (CT)-sleep hygiene and weight loss-(65 patients) or CT plus CPAP (77 patients), and 125 patients (86% males, age: 54 +/- 9 yr, BMI: 29 +/- 4 kg/m(2), AHI: 20 +/- 6, ESS: 12 +/- 4) completed the follow-up. The following outcomes were assessed at inclusion and after 3 and 6 mo of treatment: sleepiness (Epworth scale, multiple sleep latency test [MSLT]), other symptoms related to SAHS, cognitive function, and perceived health status (Functional Outcomes of Sleep Questionnaire [FOSQ], Nottingham Health profile). The relief of SAHS-related clinical symptoms was significantly greater in the CPAP group than in the CT group; the Epworth scale and FOSQ also showed more improvement in the CPAP group but did not reach significance. There were no significant differences in the other tests performed probably because the baseline values were normal. CPAP compliance was 4.8 +/- 2.2 h and treatment continuation was accepted by 62% of the patients at the end of the study. These results suggest that CPAP can be considered in treating patients with mild SAHS on the basis of an improvement in symptoms.     

The Endocrinologic Changes in Critically Ill Chronic Obstructive Pulmonary Disease Patients

ABSTRACT

Background: Alterations in the neuroendocrine system occur during critical illness. Chronic obstructive pulmonary disease (COPD) itself causes hormonal changes. The aim of this study was to determine neu roendocrine hormones of COPD patients with acute respiratory failure and to investigate the relationship between hormonal changes, mortality, and morbidity.Methods: We enrolled 21 patients (13 F/8 M) with COPD exacerbation requiring artificial airway support. Blood samples were collected on admission to the ICU, and on the day of hospital discharge. Eighteen healthy people were included as controls. Results: Female patients had lower luteinizing hormone (LH), follicle stimulating hormone (FSH), and free triiodothyronine (fT3), and higher prolactin (PRL) levels than controls on admission to the ICU (FSH: 70.3 vs. 29.3 mlU/mL; LH: 26.6 vs. 6.8 mlU/mL; fT3: 2.9 vs. 2.0 pg/mL; PRL: 12.4 vs. 21.3 ng/mL). Male patients had low testosterone and TSH and high PRL but only changes in TSH and PRL reached statistical significance (testosterone: 3.5 vs. 1.5 ng/mL, TSH: 1.1 vs. 0.5 ulU/mL, PRL: 9.7 vs. 14.2 ng/mL). Female patients had lower fT3 than males (fT3_female: 2.7 vs. fT3_male: 2.0 pg/mL). On follow-up, significantly elevated FSH and fT3 and decreased estradiol concentrations were documented among recovered women (FSH: 28.4 vs. 46.6 mlU/mL, fT3,: 2.0 vs. 2.6 pg/mL, E₂: 27.7 vs. 19.0 pg/mL). Patients had high C-reactive protein levels and acute physiologic and chronic health evaluation II scores. Mortality rate was 9.5% and a negative correlation between E₂ and duration of noninvasive mechanical ventilation and length of hospital stay was found in male patients. Conclusion: Men and women with acute respiratory failure in the presence of COPD develop significant changes in the neuroendocrine axis. Hormonal suppression vanishes with disease improvement.     

Enhancement of Cardiac Performance by Bilevel Positive Airway Pressure Ventilation in Heart Failure

BackgroundRecent studies have reported the clinical usefulness of positive airway pressure ventilation therapy with various kinds of pressure support compared with simple continuous positive airway pressure (CPAP) for heart failure patients. However, the mechanism of the favorable effect of CPAP with pressure support can not be explained simply from the mechanical aspect and remains to be elucidated.Methods and ResultsIn 18 stable chronic heart failure patients, we performed stepwise CPAP (4, 8, 12 cm H₂O) while the cardiac output and intracardiac pressures were continuously monitored, and we compared the effects of 4 cm H₂O CPAP with those of 4 cm H₂O CPAP plus 5 cm H₂O pressure support. Stepwise CPAP decreased cardiac index significantly in patients with pulmonary arterial wedge pressure (PAWP) <12 mm Hg (n = 10), but not in those with PAWP ≥12 mm Hg (n = 8). Ventilation with CPAP plus pressure support increased cardiac index slightly but significantly from 2.2 ± 0.7 to 2.3 ± 0.7 L min^?1 m^?2 (P = .001) compared with CPAP alone, regardless of basal filling condition or cardiac index.ConclusionsOur results suggest that CPAP plus pressure support is more effective than simple CPAP in heart failure patients and that the enhancement might be induced by neural changes and not simply by alteration of the preload level.     

Greek Version of the Epworth Sleepiness Scale

Background: The Epworth Sleepiness Scale (ESS) questionnaire is widely used for the assessment of daytime sleepiness in patients with sleep apnea-hypopnea syndrome (SAHS). The aim of this study was to develop a Greek version of ESS, bearing in mind that language is a barrier for application in non-English speaking populations. Methods: The forward and backward translation method by bilinguals was applied. The Greek version of ESS (ESSgr) was then administered to 130 healthy age-matched controls and 211 patients with SAHS with various levels of severity. Reproducibility of ESSgr and also the sensitivity after continuous positive airway pressure (CPAP) treatment were tested. Results: Patients and controls ESS score was 11.3 ± 5.1 and 5.6 ± 3.2, respectively (p< 0.001). Total score and individual item score were correlated in both groups. ESSgr score was correlated with body mass index and apnea-hypopnea index (p< 0.001) but not with age. Reproducibility was tested in 29 subjects, revealing no significant difference. A significant reduction was revealed (14.1 ± 4.7 vs. 6.4 ± 3.5; p< 0.001) in 37 patients who were evaluated after CPAP treatment. Conclusions: Our data validate the ESS for application in Greek-speaking populations. Despite relevant influences of language and cultural background, ESSgr is a valuable tool for clinical management and research.     

Long-term Recording of Night-Time Respiratory Symptoms in Patients with Stable COPD II–IV

Introduction: Night-time respiratory symptoms have a considerable impact on sleep and life quality in patients with chronic obstructive pulmonary disease (COPD). Lack of awareness of night-time symptoms can lead to worsened COPD control. Automated long-term monitoring of respiratory symptoms with LEOSound enables assessment of nocturnal wheezing and cough. Methods: In this observational study we investigated the prevalence and severity of cough and wheezing in patients with stable COPD [Global Initiative for Chronic Obstructive Lung Disease (GOLD) II–IV] disease for two consecutive nights with the LEOSound system. 48 patients (30 males, 63%) were eligible for inclusion, median age was 67 years, and body mass index (BMI) was 25.3 kg/m². Results: In 15 out of 48 patients (31%), we found wheezing periods for at least 10-minute duration. Wheezing periods >30 minutes were monitored in seven patients and wheezing periods >60 minutes were monitored in three patients. The maximum duration of wheezing was 470 minutes in one patient with COPD II. The median wheezing rate differed between the COPD stages and between active and non-active smokers. Cough was found in 42 patients (87.5%) with a range of 1–326 events. The cough-period-index in night one was 0.83 n/hour (P25:0.33||P75: 2.04) and night two 0.97 n/hour (P25:0.25||P75: 1.9). Most of the cough events were non-productive with a median of 0.86. Conclusions: Night-time symptoms are common in COPD patients. LEOSound offers an opportunity to evaluate objectively night-time symptoms like wheezing and cough in patients with COPD which remain otherwise unnoticed. We found a high incidence of night-time wheezing in these patients, which was related to persistant smoking.     

El síndrome de apneas-hipoapneas del sueño (SAHS) grave incrementa la excreción urinaria de eritropoyetina. Efecto del tratamiento con CPAP

Introduction

Tissue hypoxia stimulates the production of erythropoietin (EPO), the main effect of which is, in turn, to stimulate erythropoiesis. Sleep apnea-hypopnea syndrome (SAHS) is an entity characterized by repeated episodes of hypoxemia during sleep.

Forced oscillation measurements do not affect upper airway muscle tone or sleep in clinical studies.

Upper airway obstruction in the sleep apnoea/hypopnoea syndrome (SAHS) can be easily assessed by measuring respiratory impedance with the forced oscillation technique (FOT). This methodology has been proposed as a useful clinical tool both for the diagnosis of sleep breathing disorders and for continuous positive airway pressure (CPAP) titration. However, previous studies suggest that the application of high-frequency pressure oscillation to the upper airway may induce changes in the electroencephalogram (EEG) or upper airway muscle function. The effect of FOT measurements on upper airway muscle tone and EEG in clinical sleep studies was examined. Seven patients with moderate SAHS were included (age: 54+/-11 yrs; apnoea/hypopnoea index: 43+/-21 events x h(-1); body mass index: 30+/-2 kg x m(-2)). Genioglossus surface electromyogram activity (EMGgg) and EEG signal were analysed with and without FOT application (frequency: 5 Hz and 30 Hz; peak-to-peak pressure oscillation: 1 cmH2O) during stable sleep. Measurements were carried out in two different situations. Step 1: applying FOT during episodes of obstructive events or flow limitation; and step 2: during prolonged periods of normal breathing at optimal CPAP. The root mean square of EMGgg activity and fast Fourier analysis (alpha and delta bands) of the EEG signal were performed. The application of FOT did not increase EMGgg activity in any of the situations studied. In addition, no evidence of the effects on EEG was found: alpha/delta relationship: awake:0.70, baseline sleep:0.13, FOT(5 Hz):0.18, FOT(30 Hz):0.11. The presented results suggest that the use of forced oscillation technique over the ranges of frequency and amplitude proposed for clinical sleep studies does not induce changes in upper airway muscle activity and neurological variables in patients with sleep apnoea/hypopnoea syndrome.     

Insuficiencia respiratoria hipercápnica aguda en pacientes con apneas del sueño

Introduction

Acute hypercapnic respiratory failure (AHRF) is a serious condition observed in some patients with sleep apnea-hypopnea syndrome (SAHS). The objective of the present study was to study the clinical characteristics of SAHS patients who develop AHRF and their prognosis.

Patients and method

A total of 70 consecutive SAHS patients who survived an AHRF episode and 70 SAHS patients paired by age with no previous history of AHRF were prospectively studied and followed up for 3 years.

Results

The deterioration of lung function due to obesity or concomitant chronic obstructive pulmonary diseases (COPD) was common in SAHS patients with AHRF. In the multivariate analysis, the risk factors associated with AHRF were baseline PaO_2, the theoretical percentage value of the forced vital capacity, alcohol consumption, and benzodiazepines. The mortality during follow up was higher among patients who had AHRF than in the control group. The main cause of death was respiratory, and the coexistence of COPD was identified as a mortality risk factor.

Conclusions

The development of AHRF in SAHS patients is associated with a deterioration in lung function and with alcohol and benzodiazepine consumption. The patients had a higher mortality after the AHRF episode, mainly a respiratory cause. New studies are required that evaluate the different available therapeutic options in these patients.     

Nocturnal Oxygen Desaturation Index is Inversely Correlated with Airflow Limitation in Patients with Chronic Obstructive Pulmonary Disease

The concurrent diagnosis of chronic obstructive pulmonary disease (COPD) and sleep apnoea–hypopnoea syndrome (SAHS) (overlap syndrome), can contribute to worsening respiratory symptoms, but whether the severity of COPD is associated with co-morbid SAHS is unknown. We investigated whether the severity of COPD is associated with the complication of SAHS by examination of nocturnal oximetry as an alternative to polysomnography. Patients with COPD concurrently completed nocturnal oximetry, pulmonary function tests, a COPD assessment test, an Epworth sleepiness scale and a hospital anxiety and depression scale to evaluate the severity of COPD and possible concurrent presence of SAHS. We retrospectively analysed the data to assess correlation between the oxygen desaturation index (ODI) and each clinical variables and evaluated the predictors of ODI ≥ 15. This study included 103 patients (91 males, 88%) with a mean age of 72 ± 8 years and body mass index of 22 ± 3 kg/m². ODI was positively correlated with FEV₁, FEV₁/FVC and FEV₁% predicted, which meant that ODI was inversely correlated with airflow limitation. Univariate logistic regression analysis revealed that FEV₁% predicted and FEV₁/FVC were predictors of ODI ≥ 15. ODI is inversely correlated with airflow limitation and milder COPD patients may have co-morbid SAHS.     

Co-morbidities and Hyperinflation Are Independent Risk Factors of All-cause Mortality in Very Severe COPD

Background: COPD is a multi-component disease that is not sufficiently reflected by FEV₁ alone. We studied in patients with very severe COPD, which dimensions of the disease, including co-morbidities, dominate prognosis. Methods: In patients with FEV₁ < 30% predicted, anthropometric, laboratory, spirometric and body plethysmographic data, smoking status, alcohol consumption, the level of dyspnoea and exercise performance were assessed. Co-morbidities were categorized by the Charlson-index and the COPD-specific co-morbidity test (COTE). The prognostic value of multiple dimensions was explored using uni- and multivariate survival analyses regarding death from any or respiratory cause. Results: Among 209 patients included (58/151 female/male; FEV₁ 25.0 (22.0–26.9)%predicted), arterial hypertension (54.1%), hyperlipidemia (38.3%) and diabetes (19.6%) were most common, 57.9% showing a COTE-index of ≥1 point. During follow-up (28 (14–45) months), 121 patients had died, mostly (56.2%) due to respiratory causes. Age, BMI, the ratio of residual volume to total lung capacity (RV/TLC), co-morbidities in terms of the COTE- and Charlson-index, but not FEV₁, were significantly associated with all-cause and respiratory mortality. The association of the median values of the Charlson- (HR 1.911 [95%-CI 1.338–2.730]) and COTE-index (HR 1.852 [95%-CI 1.297–2.644], p < 0.001 each) with mortality was similar and stronger when combined with age. In multivariate analyses, only RV/TLC and co-morbidities were independent risk factors of all-cause mortality (p < 0.05 each). Conclusion: In very severe COPD, resting hyperinflation and co-morbidities provide the major prognostic information, whereas the association of the recently introduced COTE-index with mortality was similar to that of the established Charlson-index and even stronger when including age.     

Constant vs auto-continuous positive airway pressure in patients with sleep apnea hypopnea syndrome and a high variability in pressure requirement

STUDY OBJECTIVES: Auto-continuous positive airway pressure (CPAP) has been reported to have no more efficacy than constant CPAP in unselected patients with sleep apnea hypopnea syndrome (SAHS). The aim of this study was to evaluate patients judged to be good candidates for auto-CPAP because of a high within-night variability in pressure requirement. DESIGN: Single-blind, randomized, cross-over study (2 x 8 weeks) to compare auto-CPAP with constant CPAP. PATIENTS: Outpatients with moderate-to-severe SAHS attending the chest clinic. INTERVENTIONS: Patients were equipped at home in the auto-CPAP mode (model GK418A; Malinckrodt; Nancy, France), using a 4- to 14-cm H(2)O pressure range. Those individuals having a high within-night variability in pressure requirement, assessed at the end of a 14-day run-in period, were included in the cross-over study. Auto-CPAP was compared with constant CPAP (according to a titration night in the sleep laboratory) in terms of compliance, efficacy on apneas (assessed from the pressure monitor), and sleepiness (assessed on the Epworth sleepiness scale). MEASUREMENTS AND RESULTS: Of 90 consecutive patients with SAHS, 27 patients were selected for a within-night variability in pressure requirement exceeding a given threshold. After completion of the cross-over, 24 patients were evaluable. The median percentage of nights the machine was used was 95.5% (range, 45 to 100%) on constant CPAP, and 96.5% (range, 40 to 100%) on auto-CPAP; the median apnea index recorded by the device was 0.40/h (range, 0 to 2.40/h) on constant CPAP, and 0.45/h (range, 0 to 5.80/h) on auto-CPAP (differences not significant). The mean Epworth sleepiness score was significantly (p < 0.01) lower on auto-CPAP (5.1; SD, 2.8) than on constant CPAP (6.1; SD, 2.8). CONCLUSIONS: In patients selected for a high within-night variability in pressure requirement, auto-CPAP administered via a GK418A device was equivalent to constant CPAP based on a titration night in the sleep laboratory. Subjective ratings for sleepiness were slightly lower on auto-CPAP.