Analysis of longitudinal data unbalanced over time

Summary.  The paper considers modelling, estimating and diagnostically verifying the response process generating longitudinal data, with emphasis on association between repeated meas-ures from unbalanced longitudinal designs. Our model is based on separate specifications of the moments for the mean, standard deviation and correlation, with different components possibly sharing common parameters. We propose a general class of correlation structures that comprise random effects, measurement errors and a serially correlated process. These three elements are combined via flexible time-varying weights, whereas the serial correlation can depend flexibly on the mean time and lag. When the measurement schedule is independent of the response process, our estimation procedure yields consistent and asymptotically normal estimates for the mean parameters even when the standard deviation and correlation are misspecified, and for the standard deviation parameters even when the correlation is misspecified. A generic diagnostic method is developed for verifying the models for the mean, standard deviation and, in particular, the correlation, which is applicable even when the data are severely unbalanced. The methodology is illustrated by an analysis of data from a longitudinal study that was designed to characterize pulmonary growth in girls.     

呼气末正压通气治疗急性肺水肿

目的 :评价呼气末正压通气 (PEEP)治疗急性肺水肿的临床疗效。方法 :30例急性肺水肿患者 ,在药物治疗基础上 ,加用PEEP(3～ 8cmH2 O)机械通气治疗 ,对比治疗前后血压 (BP)、呼吸 (R)、心率(HR)、氧饱和度 (SaO2 )等动脉血气指标及胸片变化 ,同时与 30例常规药物治疗组进行对比。结果 :经PEEP机械通气治疗 0 .5～ 1h后 ,2 9例呼吸频率减慢、心率减慢 ,氧饱和度上升 ,血气指标好转 ,心功能改善 ,仅一例无效死亡。总有效率 96 .6 7%。结论 :呼气末正压通气是治疗急性肺水肿快速、有效的方法。     

无创正压通气治疗慢性阻塞性肺疾病合并Ⅱ型呼吸衰竭临床分析

目的应用无创正压通气治疗（NIPPV）老年慢性阻塞性肺疾病（COPD）并Ⅱ型呼吸衰竭的疗效观察。方法45例慢性阻塞性肺疾病急性加重期合并Ⅱ型呼吸衰竭的患者,在常规治疗的基础上,给予无创正压通气治疗,观察治疗前后的动脉血气分析和临床征象变化。并将治疗轻中度和严重Ⅱ型呼吸衰竭的疗效进行对比。结果NIPPV治疗4小时患者血气指标（pH、PaCO2、PaO2）与临床征象较治疗前有明显改善（P〈0．05）,治疗结束后,可获进一步改善（P〈0．05）。治疗轻、中度和严重Ⅱ型呼吸衰竭的疗效无明显差异。结论无创正压通气是治疗COPD并Ⅱ型呼吸衰竭患者有效手段。