Background Obstructive sleep apnea （OSA） is the most common cause of resistant hypertension, which has been proposed to result from activation of the renin-angiotensin-aldosterone system （RAAS）. We meta-analyzed t...Background Obstructive sleep apnea （OSA） is the most common cause of resistant hypertension, which has been proposed to result from activation of the renin-angiotensin-aldosterone system （RAAS）. We meta-analyzed the effects of OSA on plasma levels of RAAS components. Methods Full-text studies published on MEDL1NE and EMBASE analyzing fasting plasma levels of at least one RAAS component in adults with OSA with or without hypertension. OSA was diagnosed as an apnea-hypopnea index or respiratory disturbance index 〉 5. Study quality was evaluated using the Newcastle-Ottawa Scale, and heterogeneity was assessed using the 12 statistic. Results from individual studies were synthesized using inverse variance and pooled using a random-effects model. Subgroup analysis, sensitivity analysis, and meta-regression were performed, and risk of publication bias was assessed. Results The meta-analysis included 13 studies, of which 10 reported results on renin （n = 470 cases and controls）, 7 on angiotensin II （AnglI, n = 384）, and 9 on aldosterone （n = 439）. AnglI levels were significantly higher in OSA than in controls [mean differences = 3.39 ng/L, 95% CI： 2.00-4.79, P 〈 0.00001], while aldosterone levels were significantly higher in OSA with hypertension than OSA but not with hypertension （mean differences = 1.32 ng/dL, 95% CI： 0.58-2.07, P = 0.0005）. Meta-analysis of all studies suggested no significant differences in aldosterone between OSA and controls, but a significant pooled mean difference of 1.35 ng/mL （95% CI： 0.88-1.82, P 〈 0.00001） emerged after excluding one small-sample study. No significant risk of publication bias was detected among all included studies. Conelusions OSA is associated with higher AnglI and aldosterone levels, espe- cially in hypertensive patients. OSA may cause hypertension, at least in part, by stimulating RAAS activity.展开更多
To increase the efficiency and reliability of the thermodynamics analysis of the hydraulic system, the method based on pseudo-bond graph is introduced. According to the working mechanism of hydraulic components, they ...To increase the efficiency and reliability of the thermodynamics analysis of the hydraulic system, the method based on pseudo-bond graph is introduced. According to the working mechanism of hydraulic components, they can be separated into two categories: capacitive components and resistive components. Then, the thermal-hydraulic pseudo-bond graphs of capacitive C element and resistance R element were developed, based on the conservation of mass and energy. Subsequently, the connection rule for the pseudo-bond graph elements and the method to construct the complete thermal-hydraulic system model were proposed. On the basis of heat transfer analysis of a typical hydraulic circuit containing a piston pump, the lumped parameter mathematical model of the system was given. The good agreement between the simulation results and experimental data demonstrates the validity of the modeling method.展开更多
文摘Background Obstructive sleep apnea （OSA） is the most common cause of resistant hypertension, which has been proposed to result from activation of the renin-angiotensin-aldosterone system （RAAS）. We meta-analyzed the effects of OSA on plasma levels of RAAS components. Methods Full-text studies published on MEDL1NE and EMBASE analyzing fasting plasma levels of at least one RAAS component in adults with OSA with or without hypertension. OSA was diagnosed as an apnea-hypopnea index or respiratory disturbance index 〉 5. Study quality was evaluated using the Newcastle-Ottawa Scale, and heterogeneity was assessed using the 12 statistic. Results from individual studies were synthesized using inverse variance and pooled using a random-effects model. Subgroup analysis, sensitivity analysis, and meta-regression were performed, and risk of publication bias was assessed. Results The meta-analysis included 13 studies, of which 10 reported results on renin （n = 470 cases and controls）, 7 on angiotensin II （AnglI, n = 384）, and 9 on aldosterone （n = 439）. AnglI levels were significantly higher in OSA than in controls [mean differences = 3.39 ng/L, 95% CI： 2.00-4.79, P 〈 0.00001], while aldosterone levels were significantly higher in OSA with hypertension than OSA but not with hypertension （mean differences = 1.32 ng/dL, 95% CI： 0.58-2.07, P = 0.0005）. Meta-analysis of all studies suggested no significant differences in aldosterone between OSA and controls, but a significant pooled mean difference of 1.35 ng/mL （95% CI： 0.88-1.82, P 〈 0.00001） emerged after excluding one small-sample study. No significant risk of publication bias was detected among all included studies. Conelusions OSA is associated with higher AnglI and aldosterone levels, espe- cially in hypertensive patients. OSA may cause hypertension, at least in part, by stimulating RAAS activity.
基金Project(51175518)supported by the National Natural Science Foundation of China
文摘To increase the efficiency and reliability of the thermodynamics analysis of the hydraulic system, the method based on pseudo-bond graph is introduced. According to the working mechanism of hydraulic components, they can be separated into two categories: capacitive components and resistive components. Then, the thermal-hydraulic pseudo-bond graphs of capacitive C element and resistance R element were developed, based on the conservation of mass and energy. Subsequently, the connection rule for the pseudo-bond graph elements and the method to construct the complete thermal-hydraulic system model were proposed. On the basis of heat transfer analysis of a typical hydraulic circuit containing a piston pump, the lumped parameter mathematical model of the system was given. The good agreement between the simulation results and experimental data demonstrates the validity of the modeling method.
