A pressure controlled mechanical ventilator with an automatic secretion clearance function can improve secretion clearance safely and efficiently.Studies on secretion clearance by pressure controlled systems show that...A pressure controlled mechanical ventilator with an automatic secretion clearance function can improve secretion clearance safely and efficiently.Studies on secretion clearance by pressure controlled systems show that these are suited for clinical applications.However,these studies are based on a single lung electric model and neglect the coupling between the two lungs.The research methods applied are too complex for the analysis of a multi-parameter system.In order to understand the functioning of the human respiratory system,this paper develops a dimensionless mathematical model of doublelung mechanical ventilation system with a secretion clearance function.An experiment is designed to verify the mathematical model through comparison of dimensionless experimental data and dimensionless simulation data.Finally,the coupling between the two lungs is studied,and an orthogonal experiment designed to identify the impact of each parameter on the system.展开更多
Background:Although intensively studied in patients with cardiovascular diseases(CVDs),the prognostic value of diastolic blood pressure(DBP)has little been elucidated in patients with acute exacerbation of chronic obs...Background:Although intensively studied in patients with cardiovascular diseases(CVDs),the prognostic value of diastolic blood pressure(DBP)has little been elucidated in patients with acute exacerbation of chronic obstructive pulmonary disease(AECOPD).This study aimed to reveal the prognostic value of DBP in AECOPD patients.Methods:Inpatients with AECOPD were prospectively enrolled from 10 medical centers in China between September 2017 and July 2021.DBP was measured on admission.The primary outcome was all-cause in-hospital mortality;invasive mechanical ventilation and intensive care unit(ICU)admission were secondary outcomes.Least absolute shrinkage and selection operator(LASSO)and multivariable Cox regressions were used to identify independent prognostic factors and calculate the hazard ratio(HR)and 95%confidence interval(CI)for adverse outcomes.Results:Among 13,633 included patients with AECOPD,197(1.45%)died during their hospital stay.Multivariable Cox regression analysis showed that low DBP on admission(<70 mmHg)was associated with increased risk of in-hospital mortality(HR=2.16,95%CI:1.53–3.05,Z=4.37,P<0.01),invasive mechanical ventilation(HR=1.65,95%CI:1.32–2.05,Z=19.67,P<0.01),and ICU admission(HR=1.45,95%CI:1.24–1.69,Z=22.08,P<0.01)in the overall cohort.Similar findings were observed in subgroups with or without CVDs,except for invasive mechanical ventilation in the subgroup with CVDs.When DBP was further categorized in 5-mmHg increments from<50 mmHg to≥100 mmHg,and 75 to<80 mmHg was taken as reference,HRs for in-hospital mortality increased almost linearly with decreased DBP in the overall cohort and subgroups of patients with CVDs;higher DBP was not associated with the risk of in-hospital mortality.Conclusion:Low on-admission DBP,particularly<70 mmHg,was associated with an increased risk of adverse outcomes among inpatients with AECOPD,with or without CVDs,which may serve as a convenient predictor of poor prognosis in these patients.Clinical Trial Registration:Chinese Clinical Trail Registry,No.ChiCTR2100044625.展开更多
文摘A pressure controlled mechanical ventilator with an automatic secretion clearance function can improve secretion clearance safely and efficiently.Studies on secretion clearance by pressure controlled systems show that these are suited for clinical applications.However,these studies are based on a single lung electric model and neglect the coupling between the two lungs.The research methods applied are too complex for the analysis of a multi-parameter system.In order to understand the functioning of the human respiratory system,this paper develops a dimensionless mathematical model of doublelung mechanical ventilation system with a secretion clearance function.An experiment is designed to verify the mathematical model through comparison of dimensionless experimental data and dimensionless simulation data.Finally,the coupling between the two lungs is studied,and an orthogonal experiment designed to identify the impact of each parameter on the system.
基金National Natural Science Foundation of China(No.82170013)Sichuan Science and Technology Program(No.2022YFS0262)National Key Research Program of China(No.2016YFC1304202)
文摘Background:Although intensively studied in patients with cardiovascular diseases(CVDs),the prognostic value of diastolic blood pressure(DBP)has little been elucidated in patients with acute exacerbation of chronic obstructive pulmonary disease(AECOPD).This study aimed to reveal the prognostic value of DBP in AECOPD patients.Methods:Inpatients with AECOPD were prospectively enrolled from 10 medical centers in China between September 2017 and July 2021.DBP was measured on admission.The primary outcome was all-cause in-hospital mortality;invasive mechanical ventilation and intensive care unit(ICU)admission were secondary outcomes.Least absolute shrinkage and selection operator(LASSO)and multivariable Cox regressions were used to identify independent prognostic factors and calculate the hazard ratio(HR)and 95%confidence interval(CI)for adverse outcomes.Results:Among 13,633 included patients with AECOPD,197(1.45%)died during their hospital stay.Multivariable Cox regression analysis showed that low DBP on admission(<70 mmHg)was associated with increased risk of in-hospital mortality(HR=2.16,95%CI:1.53–3.05,Z=4.37,P<0.01),invasive mechanical ventilation(HR=1.65,95%CI:1.32–2.05,Z=19.67,P<0.01),and ICU admission(HR=1.45,95%CI:1.24–1.69,Z=22.08,P<0.01)in the overall cohort.Similar findings were observed in subgroups with or without CVDs,except for invasive mechanical ventilation in the subgroup with CVDs.When DBP was further categorized in 5-mmHg increments from<50 mmHg to≥100 mmHg,and 75 to<80 mmHg was taken as reference,HRs for in-hospital mortality increased almost linearly with decreased DBP in the overall cohort and subgroups of patients with CVDs;higher DBP was not associated with the risk of in-hospital mortality.Conclusion:Low on-admission DBP,particularly<70 mmHg,was associated with an increased risk of adverse outcomes among inpatients with AECOPD,with or without CVDs,which may serve as a convenient predictor of poor prognosis in these patients.Clinical Trial Registration:Chinese Clinical Trail Registry,No.ChiCTR2100044625.
