上气道压力测定在阻塞性睡眠呼吸暂停低通气综合征诊治中的应用

目的:利用压力测定法在上呼吸道内更直接地了解发生睡眠呼吸暂停低通气事件时上气道的动态变化.方法:经PSG确诊为阻塞性睡眠呼吸暂停低通气综合征(OSAHS)的21例患者行ApneaGraph上气道压力测定,获得不同体位时的呼吸紊乱指标、判定阻塞平面及各平面阻塞出现的频率.结果:①21例患者不同体位时平均发生的异常呼吸事件AHI:仰卧睡眠时AHI为(47.83±18.05)次/h,侧卧位AHI为(35.11±18.88)次/h,两者差异有统计学意义(P<0.05),②阻塞平面以软腭悬雍垂以上部位(成人主要是腭后区)为主,占异常呼吸事件的84.48%;软腭悬雍垂以下部位(舌后区为主)占异常呼吸事件的12.58%.结论:通过上气道压力测定,可较好地判断睡眠时患者气道阻塞部位,压力测定装置还可作为便携PSG,对OSAHS作出初步定性诊断,为治疗方案的选择提供了有参考价值的资料.     

120例健康工人肺通气功能测定

对一钢铁厂120名健康工人进行了肺通气功能测定,根据通气功能测定曲线求出VC,FVC,MVV,FEV_1,_(75),_50,_25,FEF75-85%等8项指标的均值,并利用电子计算机逐步回归法计算上述指标的预计值回归方程式,以能实际应用。     

Ultrasound assessment of skin and wound tissue: comparison with histology

Background/aims: Ultrasound is a valuable technique in dermatological assessment as it is non-invasive. This is particularly attractive for monitoring and evaluating wound healing. However, there is a limited literature on the use of ultrasound in monitoring wound healing. Methods: In this study, the structures of skin (human and porcine) and healing wounds (porcine) were visualised using ultrasound (20 MHz) and compared with histology from the same site. Measurements of various features were undertaken using both ultrasound and histometric techniques and the results from each compared. Hydroxyproline levels were also measured and correlated with ultrasound measurement of granulation tissue. Results: The echogenic characteristics of tissues are described. There was excellent correlation (r=0.96, P > 0.0001) between the ultrasound measurements and histology for porcine and human cadaver measurements. Ultrasound and histology measurements of acute porcine wounds also correlated well (r=0.96,P<0.0001). Comparison of hydroxyproline analysis with ultrasound measurements of fibrous granulation tissue (r=0.82,P > 0.001) indicates that ultrasound may be used to visualise accumulation of this tissue in wounds. Conclusions: Ultrasonography has been shown to be a useful, reliable, quantifiable technique for the assessment of wound healing.     

Assessment of total body water in paediatric patients on dialysis

BACKGROUND: Various anthropometric techniques are used to assess total bodywater in children on dialysis; however, their predictive accuracyand precision has not been validated. METHODS: We compared total body water measurements obtained by deuteriumoxide (D₂O) dilution with predictions of total body water from(1) height and weight, (2) skinfold measurements, and (3) bioelectricalimpedance analysis, using previously published formulae forhealthy children. Measurements were performed in 14 patientson peritoneal and in nine patients on haemodialysis, aged 4–22years. RESULTS: In the total population of dialysed patients, weight was thestrongest single predictor of total body water (R²=0.93) followedby the resistance index (RI=height²/impedance; R²=0.85) andheight (R²=0.93). A prediction formula based on height and weightpredicted total body water with a residual mean square error(RMSE) of 1.97 l (coefficient of variation (CV)=10.0%) and witha systematic overestimation of true total body water by 0.4%.A prediction equation based on skinfold measurements yieldeda total body water estimate with an RMSE of 2.15 1 (CV=10.5%)and overpredicted true total body water by an average of 2.2%.Using three published prediction equations incorporating RI,RMSEs of 2.78 1 (CV=14.1%) with a mean under- or overestimationof true total body water by 6.9, 7.1, and 0.8% respectively,were achieved. The prediction of total body water was optimizedby linear combinations of RI or the log-transformed sum of fourskinfolds (logsum) with weight by the following equations: total body water (1) = 9.97–3.13xlogsum +0.59xweight (kg) (1) (R² = 0.951; RMSE=1.67 1; CV = 8.17%). total body water (1) = 1.99 + 0.144 x RI (Ohm/cm²) + 0.40 x weight (kg) (2) (R² = 0.949; RMSE = 1.671; CV = 8.53%). The fit of these prediction formulae, which were derived fromthe total population, did not differ significantly between haemo-and peritoneal dialysis patients or between boys and girls. CONCLUSIONS: Both skinfold measurements and bioelectrical impedance analysiscan be used to improve the height- and weight- based predictionof total body water in children on dialysis.     

A multistate Markov chain model for longitudinal, categorical quality-of-life data subject to non-ignorable missingness

Quality-of-life (QOL) is an important outcome in clinical research, particularly in cancer clinical trials. Typically, data are collected longitudinally from patients during treatment and subsequent follow-up. Missing data are a common problem, and missingness may arise in a non-ignorable fashion. In particular, the probability that a patient misses an assessment may depend on the patient's QOL at the time of the scheduled assessment. We propose a Markov chain model for the analysis of categorical outcomes derived from QOL measures. Our model assumes that transitions between QOL states depend on covariates through generalized logit models or proportional odds models. To account for non-ignorable missingness, we incorporate logistic regression models for the conditional probabilities of observing measurements, given their actual values. The model can accommodate time-dependent covariates. Estimation is by maximum likelihood, summing over all possible values of the missing measurements. We describe options for selecting parsimonious models, and we study the finite-sample properties of the estimators by simulation. We apply the techniques to data from a breast cancer clinical trial in which QOL assessments were made longitudinally, and in which missing data frequently arose.     

Joint modelling of bivariate longitudinal data with informative dropout and left-censoring, with application to the evolution of CD4+ cell count and HIV RNA viral load in response to treatment of HIV infection

Several methodological issues occur in the context of the longitudinal study of HIV markers evolution. Three of them are of particular importance: (i) correlation between CD4+ T lymphocytes (CD4+) and plasma HIV RNA; (ii) left-censoring of HIV RNA due to a lower quantification limit; (iii) and potential informative dropout. We propose a likelihood inference for a parametric joint model including a bivariate linear mixed model for the two markers and a lognormal survival model for the time to drop out. We apply the model to data from patients starting antiretroviral treatment in the CASCADE collaboration where all of the three issues needed to be addressed.     

Feasibility study for the centralized measurement of sperm concentration

Despite several efforts to standardize methods of semen analysis, sperm count is known to be subject to large interlaboratory differences. This is especially a problem in multicentre clinical trial settings and protocols for the preparation of semen for centralized assessment of sperm concentration are suggested here. The stability of semen has been tested after fixation with formalin at different dilutions and at different temperatures for different sperm concentrations. Sperm concentrations in formalin-fixed semen (at dilutions 1 + 0.5 to 1 + 19) were stable (<20% difference from original) at all concentrations (0.1 x 10(6)/mL to 100 x 10(6)/mL) for at least 5 days at room temperature and 4 degrees C. Prolonged stability up to 5 weeks at 4 degrees C was demonstrated for the lower dilutions (1 + 0.5 and 1 + 1). Freezing of fixed semen samples was unacceptable. These results illustrate that centralized assessment of sperm concentrations is feasible.     

Ultrasound volume measurements comparing a prolate ellipsoid method with a parallel planimetric area method against a known volume

A comparison of a prolate ellipsoid method and a parallel planimetric area method for measuring volumes with ultrasound was made using phantom models of water-filled balloons scanned under set conditions. Correlation with actual volumes was significantly better with the parallel planimetric area method (p < 0.02) with 93.3% of parallel planimetric area measurements being within 5% of the actual volume compared with only 33.4% of measurements obtained with the prolate ellipsoid method. For uterine volume measurements, a parallel planimetric area method is the more suitable.     

Pain perception in man after long term spinal cord stimulation

Summary Thresholds of non-painful and painful perception for electrical stimuli are not altered significantly during dorsal column stimulation either in the area of induced paresthesia or outside it.After long term stimulation of the dorsal column the thresholds for stimuli are significantly higher within the area of induced paresthesia but not outside it.Median nerve evoked somatosensory cortical potentials are not altered by conditioning or simultaneous DC stimulation.During DCS in three of eight patients only the vibration evoked cortical potentials were attenuated in the early three components of the potential.Supported by Sonderforschungsbereich Hirnforschung und Sinnesphysiologie (SFB 70) der Deutschen Forschungsgemeinschaft (DFG) and Bundesminister für Arbeit und Sozialordnung