Validity of Asthma Control Test in Chinese patients

Background So far, in China, there has been no effective or easy procedure to define the control of asthma. This study assesses the validity of Asthma Control Test in Chinese patients. Methods Three questionnaires （Asthma Control Test, Asthma Control Questionnaire and the 30 second asthma test） were administered to 305 asthma patients from 10 teaching hospitals across China. Spirometry was also used. Asthma specialists rated the control of asthma according to patients＇ symptoms, medications and forced expiratory volume in first second. The patients were divided into noncontrolled group and controlled group according to the specialists＇ rating. Reliability, empirical validity and screening accuracy were conducted for Asthma Control Test scores. Screening accuracy was compared among 3 questionnaires. The patients＇ self rating and the specialists＇ rating were also compared. Results The internal consistency reliability of the 5-item Asthma Control Test was 0.854. The correlation coefficient between Asthma Control Test and the specialists＇ rating was 0.729, which was higher than other instruments. Asthma Control Test scores discriminated between groups of patients differing in the percent predicted forced expiratory volume in first second （F=-26.06, P〈0.0001）, the specialists＇ rating of asthma control （F=-88.24, P〈0.0001） and the Asthma Control Questionnaire scores （F=-250.57, P〈0.0001）. Asthma Control Test showed no significant difference with Asthma Control Questionnaire in the percent correctly classified, while the percent correctly classified by Asthma Control Test was much higher than 30 second asthma test. The patients＇ self rating was the same as assessment of the specialists （t=0.65, P=-0.516）. Conclusion The Asthma Control Test is an effective and practicable method for assessing asthma control in China.

Relationship of daytime blood pressure and severity of obstructive sleep apnea among Chinese： a multi-center investigation in China

Background Epidemiologic studies have shown an independent and definite association between obstructive sleep apnea （OSA） and hypertension. This study aimed to define the association between daytime blood pressure and severity of OSA in Chinese population in mainland of China. Methods Twenty university hospital sleep centers in mainland of China were invited by the Chinese Medical Association （CMA） to participate in this epidemiologic study and 2297 consecutive patients （aged 18-85 years; 1981 males and 316 females） referred to these twenty sleep centers for evaluation of OSA between January 2004 and April 2006 were prospectively enrolled. Nocturnal polysomnography was performed in each patient, and disease severity was assessed based on the apnea-hypopnea index （AHI）. These patients were classfied into four groups： non-apneic control （control, n=257） with AHI 〈5 episodes/hour; mild sleep apnea （mild, n=402） with AHI 〉5 and 〈15 episodes/hour; moderate sleep apnea （moderate, n=460） with AHI 〉15 and 〈30 episodes/hour and severe sleep apnea （severe, n=1178） with AHI 〉30 episodes/hour. Daytime blood pressure measurements were performed under standardized conditions in each patient at 10 a.m. in office on the day of referring to sleep centers for getting average value. All the patients were requested to quit medications related to blood pressure for three days before the day of assessing. Results Both daytime systolic blood pressure and diastolic blood pressure values were significantly related to AHI positively （r = 0.201 and 0.276, respectively; both P values 〈0.001） and to nadir nocturnal oxygen saturation negatively （r = -0.215 and -0.277, respectively; both P values 〈0.001）, which were the parameters of OSA severity. In two special designed mean plots, means of daytime systolic and diastolic blood pressure increased gradually with increasing AHI. Beyond AHI of 61-65, this increasing trend reached a plateau. Conclusions The results showed that OSA severity was associated with daytime blood pressure until AHI of 61-65, providing evidence for early OSA management, especially in OSA patients with concomitant hypertension.

Chronic intermittent hypoxia aggravates cardiomyocyte apoptosis in rat ovariectomized model

Background The prevalence of obstructive sleep apnea （OSA） increases after menopause in women, but remains under diagnosed because of social or lifestyle factors. It is important to evaluate the hazards of OSA on cardiovascular disease in menopausal women. We tested the hypothesis that chronic intermittent hypoxia （CIH） may aggravate cardiomyocyte apoptosis in ovariectomized （OVX） Sprague Dawley （SD） rats; the changes of anti-oxidation ability in cardiac muscles may be one of the reasons for cardiomyocyte apoptosis. Methods Forty-eight 60-day old female SD rats were randomly divided into a CIH group, OVX group, OVX±CIH （OC） group, and handled control （HC） group, and the rats were exposed either to CIH （nadir 02 6%） or handled normoxic controls. The changes of body weight and whole heart weight were measured. Super oxide dismutase （SOD） and malonaldehyde （MDA） were used to evaluate the level of oxidative stress. TdT-mediated dUTP nick end labeling （TUNEL） was used to measure apoptosis in each rat. Western blotting was used to measure apoptosis associated proteins in cardiac muscle samples from each rat. Results When compared with the HC and CIH groups, the levels of oxidative stress in the OC and OVX groups were significantly higher. The levels of SOD in the HC, CIH, OC, and OVX groups were （47.99±4.89）, （53.60±4.47）, （20.99±2.72）, and （30.64±3.79） mmol/mg protein; significantly increased in the CIH group （P 〈0.05） and significantly decreased in the OC （P 〈0.01） and OVX （P 〈0.05） groups. The levels of MDA in the HC, CIH, OVX, and OC groups were （1.63±0.20）, （1.93±0.77）, （3.30±0.39）, and （1.95_±0.20） mmol/mg protein; it significantly increased in the CIH （P 〈0.05）, OC （P 〈0.01）, and OVX （P 〈0.05） groups compared with the HC group. Bax protein expression was significantly increased and bcl-2 protein expression was significantly reduced after CIH compared with HC rats （P 〈0.05）. The protein expression of bax and bcl-2 in the OC group was not significantly different from the CIH group, but the ratio of bax/bcl-2 was significantly increased in the OC group （P 〈0.05）; this was associated with severe cardiomycyte apoptosis in the OC group. TUNEL confirmed this observation. Conclusions This study found that CIH may induce oxidative stress in OVX rats but not in CIH rats, and cause more severe cardiomyocyte apoptosis in OVX rats compared with CIH rats. This means that OVX rats exposed to CIH suffered more severe cardiac injury compared with CIH rats due to reduced antioxidation. These findings may partly explain the reason why OSA has a worse cardiovascular impact on menopausal women, and emphasize the importance of detection and early treatment of OSA in menopausal patients.

Elevated nocturnal and morning blood pressure in patients with obstructive sleep apnea syndrome

Background The nocturnal nondipping and elevated morning blood pressure （BP） in patients with obstructive sleep apnea syndrome （OSAS） have not yet been well investigated in Chinese patients. This study aimed to describe the BP profile, and to elucidate the relationships between daytime BP and nighttime BP, and between evening BP and morning BP in patients with OSAS. Methods Twenty teaching hospital sleep centers in China were organized by the Chinese Medical Association to participate in this study and 2297 patients were recruited between January 2004 and April 2006. BP assessments were made at four time points （daytime, evening, nighttime and morning） and polysomnography （PSG） was performed and subjects were classified into four groups by their apnea-hypopnea index （AHI）： control, n=213 with AHI 〈5; mild, n=420 with AHI -〉5 and 〈15; moderate, n=460 with AHI -〉15 and 〈30; and severe, n=1204 with AHI -〉30. SPSS 11.5 software package was used for statistical analysis and figure drawing. Results All the average daytime, nighttime, evening and morning BPs were positively correlated with AHI and negatively correlated with nadir nocturnal oxygen saturation. The ratios of nighttime/daytime and morning/evening average BP were positively correlated with AHI. The ratio of nighttime/daytime systolic BP became a ＂reversed BP dipping＂ pattern until the classification reached severe, while the ratio of nighttime/daytime diastolic BP became reversed at moderate. Similarly, the ratio of morning/evening diastolic BP becomes reversed even at mild. Conclusions OSAS may result in higher BP levels at all four time points. The ratios of nighttime/daytime and morning/evening BP increase with increased AHI. The increasing of diastolic BP, which is inclined to rise more quickly, is not parallel with increasing systolic BP.

Potential role of human visceral pleura in pleural fluid turnover

With continuing advanced research into pleural fluid turnover, the majority of scientists hold the view that pleural fluid is derived from the microvessels in parietal pleura and drained via parietal lymphatic vessels which empty into systemic veins. The lymphatic vessels that contribute to the pulmonary lymphatic circulation originate in the subpleural connective tissue, not directly from the visceral mesothelium. Therefore, according to the current point of view, pleural effusion absorption through the visceral pleural is normally neclligible and visceral pleura,