Hypercapnia in Overlap Syndrome: Possible Determinant Factors

We retrospectively evaluated data from 213 consecutive patients; 152 were affected by obstructive sleep apnea (OSA), 29 had OSA associated with chronic obstructive pulmonary disease (COPD), also known as overlap syndrome, and 32 had COPD. Patients with obesity-hypoventilation syndrome were not included. The aims of the study were to evaluate the anthropometric, pulmonary, and polysomnographic characteristics of patients affected by overlap syndrome compared to simple OSA and to COPD subjects and to analyze the determinants of hypercapnia in overlap syndrome. In the comparison between overlap and OSA patients, the overlap group had a significantly higher PaCO₂ (44.59 vs. 39.22 mm Hg; p < 0.01), in the presence of a similar AHI (40.46 vs. 41.59/h). Comparing overlap to COPD patients, overlap showed a significantly higher PaCO₂ value (44.59 vs. 39.63 mm Hg; p < 0.005) and had significantly less severe obstructive impairment (FEV 162.93 vs. 47.31%; FEV₁/FVC ratio 66.71 vs. 59.25%; p < 0.005). Anthropometric, pulmonary function, and polysomnographic data did not differ between normo- and hypercapnic overlap patients. The best model (stepwise multiple regression analysis) for predicting PaCO₂ in overlap patients showed r2 value 0.65: PaO₂ contributed to 38%, FEV₁ to 15%, and weight to 12%. In conclusion, the occurrence of hypercapnia in overlap patients is only partially explained by the combination of overweight and reduced respiratory function, supporting the hypothesis of a multifactorial genesis.     

Prevalence and clinical feature of the “overlap syndrome”, obstructive sleep apnea (OSA) and chronic obstructive pulmonary disease (COPD), in OSA population

Purpose

The association of chronic obstructive pulmonary disease (COPD) and obstructive sleep apnea (OSA), defined overlap syndrome by Flenley, is frequent. Aims of the present study were to assess the frequency of overlap syndrome in 168 consecutive OSA patients, and to evaluate the functional pulmonary hemodynamic, and polysomnographic consequences of this association by comparing Overlap patients with OSA patients.

Methods

From the results of the pulmonary and polysomnographic investigation, patients were classified as OSA patients (group 1), having an apneas/hypopneas index (AH/I) > 15/hr, and Overlap patients (group 2), i. e. OSA patients with an obstructive spirographic pattern (FEV1<60%, FEV1/FVC<65%, RV>130%, RV/TLC>140% of predicted value) not reversible after beta2 agonist inhalation. Group 1 consisted of 135 Patients (115 males, 20 females, age 56+/-10 yr, BMI 32+/-6 Kg/m²); the group 2 included 33 patients (30 males, 3 females, age 56+/-11 yr., BMI 34 +/- 6 Kg/m²).

Results

The OSA and Overlap patients were similar in most respects: age, BMI, clinical characteristic. In awake Overlap patients had lower PaO₂, higher PaCO₂ and Ppa (p<0.001), and an obstructive spirographic pattern, as compared to OSA patients. During sleep the overlap group had a higher AH/I and a lower mean SaO₂ (p<0.05), a reduction of the sleep efficency (p<0.05), and a reduction in the duration of 1NREM and REM sleep stage (p<0.05), as compared to group 1.

Conclusion

In conclusion, an associated COPD is observed in more than 19% of OSA patients. Overlap patients are at increased risk of developing pulmonary hypertension and show a poorer quality of sleep as compared with OSA patients. The possibility of developing cor pulmonale should be given particular attention in the diagnosis and follow-up of Overlap patients.     

Risk of New-Onset Atrial Fibrillation in Elderly Patients with the Overlap Syndrome: A Retrospective Cohort Study

Background Co-existence of obstructive sleep apnea (OSA) and chronic obstructive pulmonary disease (COPD) is referred to as overlap syndrome. Overlap patients have greater degree of hypoxia and pulmonary hypertension than patients with OSA or COPD alone. Studies showed that elderly patients with OSA alone do not have increased risk of atrial fibrillation (AF) but it is not known if overlap patients have higher risk of AF. Objective To determine whether elderly patients with overlap syndrome have an increased risk of AF. Methods In this single center, community-based retrospective cohort analysis, data were collected on 2,873 patients > 65 years of age without AF, presenting in the year 2006. Patients were divided into OSA group (n = 60), COPD group (n = 416), overlap syndrome group (n = 28) and group with no OSA or COPD (n = 2369). The primary endpoint was incidence of new-onset AF over the following two years. Logistic regression was performed to adjust for heart failure (HF), coronary artery disease, hypertension (HTN), cerebrovascular disease, cardiac valve disorders, diabetes mellitus, hyperlipidemia, chronic kidney disease (CKD) and obesity. Results The incidence of AF was 10% in COPD group, 6% in OSA group and 21% in overlap syndrome group (P < 0.05). After adjusting for age, sex, HF, CKD, and HTN, patients with overlap syndrome demonstrated a significant association with new-onset AF (OR = 3.66, P = 0.007). HF, CKD and HTN were also significantly associated with new-onset AF (P < 0.05). Conclusion Among elderly patients, the presence of overlap syndrome is associated with a marked increase in risk of new-onset AF as compared to the presence of OSA or COPD alone.     

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.     

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.     

Evaluation of Right Ventricular Remodeling Using Cardiac Magnetic Resonance Imaging in Co-Existent Chronic Obstructive Pulmonary Disease and Obstructive Sleep Apnea

Abstract

Untreated chronic obstructive pulmonary disease (COPD) co-existing with obstructive sleep apnea (OSA), also known as overlap syndrome, has higher cardiovascular mortality than COPD alone but its underlying mechanism remains unclear. We hypothesize that the presence of overlap syndrome is associated with more extensive right ventricular (RV) remodeling compared to patients with COPD alone. Adult COPD patients (GOLD stage 2 or higher) with at least 10 pack-years of smoking history were included. Overnight laboratory-based polysomnography was performed to test for OSA. Subjects with an apnea-hypopnea index (AHI) >10/h were classified as having overlap syndrome (n = 7), else classified as having COPD-only (n = 11). A cardiac MRI was performed to assess right and left cardiac chambers sizes, ventricular masses, and cine function. RV mass index (RVMI) was markedly higher in the overlap group than the COPD-only group (19 ± 6 versus 11 ± 6; p = 0.02). Overlap syndrome subjects had a reduced RV remodeling index (defined as the ratio between RVMI and RV end-diastolic volume index) compared to the COPD-only group (0.27 ± 0.06 versus 0.18 ± 0.08; p = 0.02). In the overlap syndrome subjects, the extent of RV remodeling was associated with severity of oxygen desaturation (R² = 0.65, p = 0.03). Our pilot results suggest that untreated overlap syndrome may cause more extensive RV remodeling than COPD alone.     

Cardiac Sympathetic Hyperactivity in Patients with Chronic Obstructive Pulmonary Disease and Obstructive Sleep Apnea

Obstructive sleep apnea (OSA) and chronic obstructive pulmonary disease (COPD) coexist in 0.5–1% of the general population. Both OSA and COPD are associated with increased sympathetic nervous activity, and patients affected by both disorders have higher risk for increased morbidity and mortality as compared with patients with COPD or OSA alone.

We tested the hypothesis that patients with COPD and OSA (Overlap syndrome) have higher sympathetic and lower parasympathetic modulation of heart rate variability (HRV) in comparison with patients suffering from COPD or OSA alone.

HRV indices in the frequency domain were evaluated from daytime electrocardiographic recordings in 14 patients with both severe OSA (apnea–hypopnea index ≥ 30) and mild-to-moderate COPD and compared with those with OSA (n = 24) or COPD (n = 16) alone.

We found that, in the Overlap syndrome group, high-frequency (HF, 0.4–0.15 Hz) power was significantly lower (0.18 nu vs 0.34 nu in OSA and 0.44 nu in COPD patients, p < 0.01) and low-frequency (LF, 0.15–0.05 Hz) power was significantly greater (0.82 nu vs 0.66 nu in OSA and 0.57 nu in COPD patients, p < 0.01) compared with COPD and OSA groups. Patients with both OSA and COPD had higher LF/HF ratio as compared with patients in OSA and COPD groups (4.5 [5.9] vs 1.9 [2.6] and 1.3 [1.3], respectively, p < 0.01). For the Overlap syndrome group, there was a significant direct relationship between LF/HF ratio and residual volume (r² = 0.62, p = 0.007).

These findings show that patients with both OSA and COPD have higher sympathetic modulation of heart rate compared with those with OSA or COPD alone. Furthermore, the findings provide a potential mechanism for the increased morbidity and mortality reported in patients suffering from both disorders, suggesting new therapeutic perspectives in Overlap syndrome.     

Heart Failure Impairs Muscle Blood Flow and Endurance Exercise Tolerance in COPD

Heart failure, a prevalent and disabling co-morbidity of COPD, may impair cardiac output and muscle blood flow thereby contributing to exercise intolerance. To investigate the role of impaired central and peripheral hemodynamics in limiting exercise tolerance in COPD-heart failure overlap, cycle ergometer exercise tests at 20% and 80% peak work rate were performed by overlap (FEV₁ = 56.9 ± 15.9% predicted, ejection fraction = 32.5 ± 6.9%; N = 16), FEV₁-matched COPD (N = 16), ejection fraction-matched heart failure patients (N = 15) and controls (N = 12). Differences (Δ) in cardiac output (impedance cardiography) and vastus lateralis blood flow (indocyanine green) and deoxygenation (near-infrared spectroscopy) between work rates were expressed relative to concurrent changes in muscle metabolic demands (ΔO₂ uptake). Overlap patients had approximately 30% lower endurance exercise tolerance than COPD and heart failure (p < 0.05). ΔBlood flow was closely proportional to Δcardiac output in all groups (r = 0.89–0.98; p < 0.01). Overlap showed the largest impairments in Δcardiac output/ΔO₂ uptake and Δblood flow/ΔO₂ uptake (p < 0.05). Systemic arterial oxygenation, however, was preserved in overlap compared to COPD. Blunted limb perfusion was related to greater muscle deoxygenation and lactate concentration in overlap (r = 0.78 and r = 0.73, respectively; p < 0.05). ΔBlood flow/ΔO₂ uptake was related to time to exercise intolerance only in overlap and heart failure (p < 0.01). In conclusion, COPD and heart failure add to decrease exercising cardiac output and skeletal muscle perfusion to a greater extent than that expected by heart failure alone. Treatment strategies that increase muscle O₂ delivery and/or decrease O₂ demand may be particularly helpful to improve exercise tolerance in COPD patients presenting heart failure as co-morbidity.     

Survival Benefit of CPAP Favors Hypercapnic Patients with the Overlap Syndrome

Background

Patients with the combination of chronic obstructive pulmonary disease (COPD) and obstructive sleep apnea (OSA), known as the “overlap syndrome,” have a substantially greater risk of morbidity and mortality compared to those with either COPD or OSA alone. The study’s objective was to report on the long-term outcome of hypercapnic (PaCO₂ ≥ 45 mmHg) and normocapnic patients with the overlap syndrome treated with continuous positive airway pressure (CPAP).

Methods

A nonconcurrent cohort of consecutive patients with the overlap syndrome was followed for a median duration of 71 months (range 1–100) at a VA sleep center. All patients were managed according to the prevailing recommendations of both diseases. The end point of the study was all-cause mortality.

Results

Of the 271 patients identified, 104 were hypercapnic (PaCO₂ = 51.6 ± 4.3 mmHg). Both normocapnic and hypercapnic patients had comparable apnea–hypopnea indexes (AHI) (29.2 ± 23.8 and 35.2 ± 29.2/h, respectively; p = 0.07) and similar adherence rates to CPAP (43 and 42 %, respectively, p = 0.9). Survival analysis revealed that hypercapnic patients who were adherent to CPAP had reduced mortality compared to nonadherent hypercapnic patients (p = 0.04). In contrast, the cumulative mortality rate for normocapnic patients was not significantly different between the adherent and the nonadherent group (p = 0.42). In multivariate analysis, the comorbidity index was the only independent predictor of mortality in normocapnic patients with the overlap syndrome [hazard ratio (HR) 1.68; p < 0.001] while CPAP adherence was associated with improved survival (HR 0.65; p = 0.04).

Conclusions

CPAP mitigates the excess risk of mortality in hypercapnic patients but not in normocapnic patients with the overlap syndrome.     

Hyperinflation is Associated with Lower Sleep Efficiency in COPD with Co-existent Obstructive Sleep Apnea

ABSTRACT

Prior research has shown that individuals with obstructive lung disease are at risk for sleep fragmentation and poor sleep quality. We postulated that patients with chronic obstructive pulmonary disease (COPD) and obstructive sleep apnea (known as overlap syndrome) who have more severe lung disease, as measured by lung hyperinflation (inspiratory capacity/total lung capacity), would have greater sleep disturbances independent of traditional measures of sleep apnea. We performed a retrospective chart review of consecutive patients evaluated and treated in an academic pulmonary clinic for overlap syndrome. Pulmonary function tests and polysomnogram data were collected. Thirty patients with overlap syndrome were included in the analysis. We found significant univariable associations between sleep efficiency and apnea/hypopnea index (β = ?0.285, p = 0.01) and between sleep efficiency and lung hyperinflation (β = 0.654, p = 0.03). Using multivariable linear regression, the relationship between sleep efficiency and lung hyperinflation remained significant (β = 1.13, p = 0.02) after adjusting for age, sex, body mass index, apnea/hypopnea index, FEV₁% predicted, oxygen saturation nadir, medications, and cardiac disease. We conclude that increased severity of hyperinflation is associated with worse sleep efficiency, independent of apnea and nocturnal hypoxemia. The mechanisms underlying this observation are uncertain. We speculate that therapies aimed at reducing lung hyperinflation may improve sleep quality in patients with overlap syndrome.     

Overlap syndrome: an indication for sleep studies?

Background  

The coexistence of obstructive sleep apnea (OSA) and chronic obstructive pulmonary diseases (COPD) is known as overlap syndrome (OS); it occurs in 10–20% of patients with OSA. Patients with OS have a higher risk of pulmonary hypertension and worse nocturnal hypoxemia than those with either disease alone. Differences may be seen according to severity of COPD, anthropometric measures, and polysomnography (PSG) features of patients. Recent studies have suggested that long-term use of continuous positive airway pressure for OSA is associated with worsening of coexistent COPD. This stresses the importance of identifying this subgroup of patients in order to provide adequate therapy.     

What is the difference between FEV1 change in percentage predicted value and change over baseline in the assessment of bronchodilator responsiveness in patients with COPD?

Background

Several criteria are clinically applied in the assessment of significant bronchodilator responsiveness in chronic obstructive pulmonary disease (COPD). The present study aimed to investigate the differences in various degree of severity of COPD among these criteria.

Methods

After 400 micrograms of salbutamol administered via spacer by metered dose inhaler (MDI), forced expiratory volume in one second (FEV₁) and forced vital capacity (FVC) changes (including percentage change, absolute change and absolute change in percentage predicted value) were retrospectively analysed in 933 stable patients with mild-to-very-severe COPD. Significant bronchodilator responsiveness was assessed using American Thoracic Society and European Respiratory Society (ATS-ERS) criterion based on FEV₁ or/and FVC (both ≥12% increase over baseline and ≥200 mL) and FEV₁ percentage predicted criterion (≥10% absolute increase in percentage predicted FEV₁) in different grades of COPD.

Results

Of the patients [age 66.8 years, baseline FEV₁ 974 mL (39.3% predicted) and FVC 2,242 mL], mean improvements were 126 mL in FEV₁ and 265 mL in FVC; 21.4% and 45.3% met ATS-ERS criterion based on FEV₁ and FVC, respectively; and 13.5% met FEV₁ percentage predicted criterion. The responsive ratios of ATS-ERS criterion based on FEV₁ to FEV₁ percentage predicted criterion in grade I, II, III and IV of COPD were 0.95^:1.26^:2.53^:6.00, respectively (P<0.01 in grade II and P<0.001 in grade III). As the degree of severity increased, the mean improvement of FEV₁ was reduced; on the contrary, that of FVC was increased.

Conclusions

Compared with FEV₁ percentage predicted criterion, ATS-ERS criterion based on FEV₁ as well as FVC, the later in particular, detected a larger percentage of patients with significant responsiveness. The increasing difference was relevant as a function of the severity of airflow obstruction.KEY WORDS : Airflow obstruction, bronchodilator responsiveness, chronic obstructive pulmonary disease (COPD), forced vital capacity (FVC), forced expiratory volume in one second (FEV₁)     

Acute Bronchodilator Response Has Limited Value in Differentiating Bronchial Asthma from COPD

Background. Acute responsiveness to inhaled bronchodilators is often used to differentiate between bronchial asthma and chronic obstructive pulmonary disease (COPD). The response can be expressed in terms of a change in FEV₁ and FVC in several ways—as absolute change, change as percent of baseline value, or as percent of predicted value with different thresholds for a positive test. A comprehensive evaluation of the diagnostic value of these different methods of expressing the acute bronchodilator response has not been carried out. Methodology. Response to inhaled salbutamol was measured by spirometry in 200 asthmatics and 154 patients with COPD. The sensitivity, specificity, and positive and negative predictive values of different methods of expressing responsiveness were calculated. Receiver operative characteristic curves were obtained. Results. None of the expressions of response gave a clear-cut separation between the two diseases. A ΔFEV₁≥ 0.2 L gave the most satisfactory combination of sensitivity (73%) and specificity (80%) and the highest positive (82%) and negative predictive values (69%) for diagnosing asthma. These values were superior to those obtained for the ERS or the ATS criteria for reversibility (ΔFEV₁%predicted ≥ 9% and ΔFEV₁ of ≥ than 12% and 0.2 L over the baseline, respectively), which had almost similar diagnostic characteristics. This was confirmed by the area under curve of the ROC plots. Expressions of response in terms of changes in FVC were unsatisfactory in separating the two diseases. Conclusions. It was concluded that the test of acute bronchodilator responsiveness has limited diagnostic value in separating asthma and COPD.     

Detection and prevalence of chronic obstructive pulmonary disease in a cardiovascular clinic: evaluation using a hand held FEV₁/FEV₆ meter and questionnaire

Background and objective: COPD is one of the leading causes of morbidity and mortality worldwide, and its prevalence continues to increase. Although spirometry is indispensable for the diagnosis of COPD, other simple and reliable tools are necessary for screening of COPD because spirometry is not widely available. This study investigated the usefulness of a combination of an electronic FEV₁/FEV₆ meter (PiKo‐6) with a COPD questionnaire as a screening method in patients with cardiovascular diseases. Methods: The PiKo‐6 and the COPD questionnaire of the International Primary Care Airways Group were used to screen patients attending a cardiovascular outpatient clinic. Patients with FEV₁/FEV₆ < 70% were defined as having airflow limitation. Patients diagnosed with airflow limitation underwent spirometry. Using data from the PiKo‐6 and the COPD questionnaire, patients were assigned to a COPD group or a non‐COPD group. The relationship between PiKo‐6 measurements and spirometry was also evaluated. Results: Among 753 patients, 82 (10.9%) showed airflow limitation when assessed with the PiKo‐6. Of these patients, 79 (10.5%) were assigned to the COPD group. FEV₁, FEV₆ and FEV₁/FEV₆, as measured with the PiKo‐6, correlated significantly with FEV₁, FVC and FEV₁/FVC, respectively, as measured by spirometry (r = 0.865, 0.751 and 0.57). Among the cardiovascular comorbidities, heart failure and ischaemic heart disease showed slightly stronger associations with airflow limitation (13.8% and 12.5%, respectively). Conclusions: Combination of the PiKo‐6 with a COPD questionnaire may be a useful and feasible method of identifying undiagnosed COPD patients attending a cardiovascular outpatient clinic.     

Prevalence and features of asthma–chronic obstructive pulmonary disease overlap in Northern Italy general population

Objective: There is controversy about the diagnostic criteria, prevalence, symptoms, and spirometry characteristics of asthma–chronic obstructive pulmonary disease (COPD) overlap (ACO). Recent data indicate that the fixed method for diagnosing airway obstruction (AO) may overestimate ACO prevalence in the elderly, and a variable method may be more accurate. We aimed at estimating ACO prevalence in a general population sample and comparing patient and clinical features in subjects with ACO, COPD, and asthma. Methods: We analyzed data from a cross-sectional study estimating COPD prevalence in randomly selected adults aged 20–79 years in Verona, Italy, and estimated prevalence and analyzed characteristics of asthma, COPD, and ACO. ACO was defined as AO (Forced Expiratory Volume in one second–FEV₁/ Forced Vital Capacity–FVC < Lower Limit of Normal–LLN), highly positive bronchodilator test (≥15% increase in FEV₁ and FVC ≥400 mL), and personal self-reported history of physician diagnosed asthma and atopy. Results: One thousand two hundred and thirty-six patients were included; 207 (16.7%) had asthma, COPD, or ACO (mean ages: 61.2, 59.7, and 57.2 years, respectively). The 3 groups had similar clinical and demographic variables; however, spirometry revealed differences between ACO and COPD patients, particularly post-bronchodilator FEV₁ reversibility, which was detected in ACO and asthma patients but not in those with COPD. Conclusion: ACO prevalence in Northern Italy was estimated at 2.1%, in the range of values reported by previous studies. Marked differences between ACO and COPD revealed by spirometry may have important clinical implications in terms of treatment for patients with ACO.     

Overnight Changes in Lung Function of Obese Patients with Obstructive Sleep Apnoea

Purpose

Obstructive sleep apnoea (OSA) is a prevalent disorder, characterised by collapse of the upper airways during sleep. The impact of sleep-disordered breathing on pulmonary function indices is however currently not well described. The aim of the study was to evaluate diurnal change in lung function indices in a cohort of patients with OSA and relate pulmonary function changes to disease severity.

Methods

42 patients with OSA and 73 healthy control subjects participated in the study. Asthma and COPD were excluded in all volunteers following a clinical and spirometric assessment. Spirometry was then performed in all subjects in the evening and the morning following a polysomnography study.

Results

There was no difference in evening or morning FEV₁ or FVC between patients and control subjects (p > 0.05). Neither FEV₁ nor FVC changed in control subjects overnight (p > 0.05). In contrast, FEV₁ significantly increased from evening (2.18/1.54–4.46/L) to morning measurement (2.26/1.42–4.63/L) in OSA without any change in FVC. The FEV₁ increase in OSA was related to male gender, obesity and the lack of treatment with statins or β-blockers (all p < 0.05). A tendency for a direct correlation was apparent between overnight FEV₁ change and RDI (p = 0.05, r = 0.30).

Conclusions

Diurnal variations in spirometric indices occur in patients with OSA and FEV₁ appears to increase in subjects with OSA overnight. These changes occur in the absence of change in FVC and are directly related to the severity of OSA. These findings dictate a need to consider time of lung function measurement.

     

Predicting optimal continuous positive airway pressure in Japanese patients with obstructive sleep apnoea syndrome

Background and objective: Several algorithms that predict the optimal CPAP have been developed for Caucasian patients with OSA syndrome, but these algorithms do not allow for racial differences in craniofacial anatomy. We investigated whether an equation that included data on craniofacial structure, physique and severity of OSA could more accurately predict the optimal CPAP for Japanese patients with OSA syndrome. Methods: In 170 Japanese patients with OSA syndrome, the optimal CPAP was determined by manual titration during polysomnography. An equation predicting the optimal pressure was derived from anthropometric, polysomnographic and cephalometric data. This equation was validated in another 110 Japanese patients with OSA syndrome. Results: Stepwise multiple regression analysis identified AHI, BMI, mean SaO₂ and a cephalometric parameter: the angle between a line from point B to the menton (Me) and a line from Me to the hyoid bone (H) (BMeH), as independent predictors of optimal CPAP. The following equation was constructed to predict the optimal CPAP: 27.78 + (0.041 × BMeH) + (0.141 × BMI) + (0.040 × AHI) ? (0.312 × mean SaO₂). This equation accounted for 47% of the variance in optimal pressure (R² = 0.47, P < 0.0001). The measured optimal pressure and the pressure calculated using this equation were very similar in the other 110 patients with OSA syndrome (9.5 ± 3.0 and 9.2 ± 2.1 cmH₂O, respectively). Conclusion: Optimal CPAP was more accurately predicted by combining a cephalometric parameter with BMI and polysomnographic data in Japanese patients with OSA, suggesting that craniofacial structure may be important in the pathogenesis of OSA syndrome among Asians.     

Overlap syndrome: Additive effects of COPD on the cardiovascular damages in patients with OSA

The chronic obstructive pulmonary disease (COPD) and obstructive sleep apnea (OSA) have been recently much focused as independent risks for cardiovascular disease. Furthermore, the complication of both has a worse prognosis compared with patients with only one of these diseases. However, the details of the underlying mechanisms of this worsened prognosis have not been clear. The cross-sectional study was conducted to examine whether the overlap of COPD augment the increase in arterial stiffness in subjects with OSA. If so, we examined the exaggeration of nocturnal hypoxemia and its related inflammation are related to this augmentation of increased arterial stiffness. In 524 male subjects with OSA diagnosed by polysomnography (apnea-hypopnea index >5/h) (52?±?14 years old), the forced expiratory volume at 1?s/the forced vital capacity (FEV(1)/FVC) ratio, brachial-ankle pulse wave velocity (baPWV), blood C-reactive protein (CRP) and B-natriuretic peptide (BNP) levels were measured. The prevalence rate of COPD was 12% in this study subjects. Plasma BNP levels and the crude (median value, 17.2 vs. 14.1?m/s, p?相似文献   

Association between sleep apnea severity and blood coagulability: treatment effects of nasal continuous positive airway pressure

A prothrombotic state may contribute to the elevated cardiovascular risk in patients with obstructive sleep apnea (OSA). We investigated the relationship between apnea severity and hemostasis factors and effect of continuous positive airway pressure (CPAP) treatment on hemostatic activity. We performed full overnight polysomnography in 44 OSA patients (mean age 47±10 years), yielding apnea–hypopnea index (AHI) and mean nighttime oxyhemoglobin saturation (SpO₂) as indices of apnea severity. For treatment, subjects were double-blind randomized to 2 weeks of either therapeutic CPAP (n=18), 3 l/min supplemental nocturnal oxygen (n=16) or placebo–CPAP (<1 cm H₂O) (n=10). Levels of von Willebrand factor antigen (VWF:Ag), soluble tissue factor (sTF), D-dimer, and plasminogen activator inhibitor (PAI)-1 antigen were measured in plasma pre- and posttreatment. Before treatment, PAI-1 was significantly correlated with AHI (r=0.47, p=0.001) and mean nighttime SpO₂ (r=−0.32, p=0.035), but these OSA measures were not significantly related with VWF:Ag, sTF, and D-dimer. AHI was a significant predictor of PAI-1 (R ²=0.219, standardized β=0.47, p=0.001), independent of mean nighttime SpO2, body mass index (BMI), and age. A weak time-by-treatment interaction for PAI-1 was observed (p=0.041), even after adjusting for age, BMI, pre-treatment AHI, and mean SpO₂ (p=0.046). Post hoc analyses suggested that only CPAP treatment was associated with a decrease in PAI-1 (p=0.039); there were no changes in VWF:Ag, sTF, and D-dimer associated with treatment with placebo–CPAP or with nocturnal oxygen. Apnea severity may be associated with impairment in the fibrinolytic capacity. To the extent that our sample size was limited, the observation that CPAP treatment led to a decrease in PAI-1 in OSA must be regarded as tentative.