Cardiac output measurement by the thermodilution method: An in vitro test of accuracy of three commercially available automatic cardiac output computers

Objective To describe the accuracy and the reproducibility of the thermodilution flow measurements obtained using 3 commercially available cardiac output computers commonly used in intensive care units.Design An experimental in vitro study. Twelve different values of control flow (Qctr) were measured (Qmsr) using 3 different cardiac output computers (Abbott Critical Care System, Oximetrix 3 SvO₂/CO Computer, Baxter Oximeter/Cardiac Output Computer SAT-1^TM; American Edwards Laboratories, 9520 A Cardiac Output Computer). Standard equipment and techniques were employed, taking account of the specific weight and heat of warm water relative to blood. In addition, separate sets of measurements were performed in order to investigate the effect on Qmsr of some variables which may influence the indicator loss (time for injection, depth of immersion of the catheter, temperature of the injected fluid).Setting Our laboratory, inside the intensive care unit.Measurements and results The analysis of the linear regression of Qmsr versus Qctr (r values between 0.992 and 0.984; residual standard deviation values comprised between 0.24 and 0.49 l/min; intercepts and slopes not significantly different from identity line), the values of the percentage errors (PE=[Qctr–Qmsr]·100/Qctr; PE mean values 7.9, 5.0 and 13.1), and those of the coefficients of variability (CV=standard deviation mean value, %; CV mean values 5.4, 5.8 and 4.6), show a good level of accuracy and reproducibility of the measurements. Our data confirm previously reported results. Furthermore, the cumulative effect of variables capable of influencing the indicator loss, even if corrected according to the calculation constant the manufacturers provide, was found to result in statistically significant changes of Qmsr.Conclusion The accuracy and reproducibility of the automatic cardiac computers tested is sufficient for practical clinical purpose. It may also depend on the modality of injection of the cooling bolus, which may significantly influence the effective indicator losses.     

动态血压正常高限者的左室肥厚

目的：观察动态血压为正常高限者的左室肥厚情况,为该患者群靶器官损害的防治策略提供依据。方法：根据２４小时动态血压监测结果将病人分为３组：Ｎ组（正常血压组）、ＮＨ组（血压正常高限组）和Ｈ组（高血压组）。以超声心动图检测左室舒张末期内径,舒张末期室间隔和左室后壁厚度等,计算左室重量指数（ＬＶＭＩ）。结果：Ｈ组（１２９±４１）和ＮＨ组（１１５±３２）的ＬＶＭＩ明显高于Ｎ组（９７±２３,Ｐ＝０．００００１和０．００５）,Ｈ组和ＮＨ组间无统计学差异。结论：动态血压正常高限者左室肥厚程度明显重于血压完全正常者。对该人群亦应积极采取措施预防和治疗靶器官损害     

A method for the follow-up of clusters of adverse reproductive outcomes

Clusters of adverse reproductive outcomes are reported with increasing frequency to public health authorities. Most are random events and only a very small proportion is likely due to identifiable environmental agents. Often, a preliminary study confirms the existence of a spatial and temporal excess but no biologically plausible cause is found. These cases require a follow-up of incidence to identify any continuing excess. A conceptually simple fixed window technique of follow up is proposed. The power of the test is mainly influenced by the magnitude of the increase in rate, the number of adverse outcomes selected for observation and the acceptable false alarm rate. This technique has several advantages compared with other currently used methods. From a public health point of view, two important factors are to be considered in setting the parameters of the test: the delay in providing an answer for the community and the availability of resources for conducting environmental investigations.     

Development and inhibition of the target phenomenon in tenotomized rat muscle

Summary The sequence of development of the target phenomenon in tenotomized gastrocnemius muscle was studied: the presence of target fibres was preceded by the occurrence of contraction bands and of moth eaten appearance of the fibres. This phenomenon was far more pronounced and occurred earlier in type II than in type I fibres.This target phenomenon and the contraction artefacts could be inhibited in the tenotomized muscles by simultaneous neurotomy or immobilization of the muscle with a plaster cast. Delayed denervation inhibited also the target phenomenon, if performed less than 5 days after the tenotomy. These series of experiments seem to indicate that the target phenomenon occurs in more irritable muscle fibres and that muscular activity is needed for its development.     

Biventricular Bypass: Alternative to Univentricular Bypass and Total Artificial Heart–Bridge

Left ventricular and biventricular bypasses (LVBs, BVBs) were performed in 102 experiments in sheep, goats, and donkeys. Biventricular bypass was performed in the assisted circulation mode or in the paracorporeal artificial heart bridge (PCAHB) mode when the natural heart fibrillates. During implantation of artificial ventricles instead of a heart-lung bypass, counterpulsation was used. Several types of connective conduits were developed and tested in experiments. The conduits included bifurcational connective pipes that permit "intake" of blood into artificial ventricles from atria and ventricles of the natural heart simultaneously and consequently provide effective blood flow through shunts not depending on the state of the natural heart (acute cardiac weakness or asystole). Monitoring gas content (PO2, PCO2, and pH) in the myocardium of both ventricles suggested development of right ventricular failure under conditions of LVB before hemodynamic changes occurred and confirmed the preferability of BVB over other methods of assisted circulation, as it is most effective and capable of normalizing short-term cardiac disturbances in the course of the 1st 2 days. Survival time of experimental animals (2-3 days for dogs, 5-12 days for sheep, goats, and donkeys) is sufficient to overcome acute cardiac insufficiency. This suggests that BVB in the assisted circulation mode or PCAHB mode can serve as a bridge for cardiac transplantation for the time of search for the available organ.     

Correlated, simultaneous, multiple-wavelength optical monitoring in vivo of localized cerebrocortical NADH and brain microvessel hemoglobin oxygen saturation

Current forms of brain monitoring, such as electroencephalography (EEG), have had limited clinical utility. The EEG records spontaneous cerebrocortical activity and thus is an indirect indicator of metabolic demand and, to a lesser extent, an indicator of mismatch of supply versus demand. Ischemia modulates EEG activity in ways that can usually be detected, but EEG patterns can be similarly modulated by many other factors, including temperature and pharmacologic manipulation. This in vivo study in physiologically monitored animals evaluated the use of correlated optical spectroscopy, performed with an instrument having a fiberoptic light-guide bundle in contact with the cerebral cortex, for the simultaneous monitoring of cerebrovascular oxygen availability and intracellular oxygen delivery. A highly specific monitor of cerebral intracellular oxygen supply, the cerebrocortical intramitochondrial NADH redox state, was monitored in vivo with a fluorescence technique. Absorption spectroscopy was used concurrently to monitor hemoglobin content (blood volume) and oxygen saturation in the microcirculation. Correlated changes in optical signals from cerebrocortical NADH and hemoglobin were studied in a swine model (n=7) of nitrogen hypoxia. Measurements were made at four wavelengths with a time-division, multiplexed fluorometer/reflectometer. Because the NADH fluorescence signal at 450 nm is affected by local changes in blood volume, a corrected fluorescence signal is usually calculated. In previous studies, where only two wave lengths have been measured, attempts at correction were based on reflectance at the excitation wavelength (366 nm). We compared estimators of changes in microcirculatory blood volume using reflection at two wavelengths: 366 nm and 585 nm, the wavelengths for maximum and isobestic absorption. The results of the studies were as follows: (1) during transient hypoxia, NADH and local hemoglobin saturation signals changed in concert with arterial pulse oximetry, with changes in NADH lagging behind changes in saturation by an average of 5.3 seconds; (2) after hypocapnic ventilation to a mean Paco ₂ of 20.2 ± 0.8 mm Hg, NADH increased by 11.5 ± 8.7% (as compared with maximal change during anoxia), local hemoglobin saturation decreased by 7.7 ± 6.4%, and local blood volume decreased by 12.5 ± 13%, while arterial SpO₂ was unchanged; (3) our two measures of local blood volume were closely correlated during carbon dioxide perturbations, but poorly correlated during hypoxic perturbation; and (4) NADH fluorescence provided a more rapid, sensitive indicator of oxygen deprivation than did the EEG. During transient hypoxia, EEG changes occurred 57.4 ± 10.4 seconds after the onset of decline in local hemoglobin saturation, after NADH had completed 50% of its maximal increase.This work was supported in part by research grants from the NIH (GM34767), the Academic Senate of the University of California, and the UCSF Anesthesia Research Foundation.     

Analysis of intracranial pressure

Methods for the acquisition and analysis of intracranial pressure (ICP) signals are reviewed from clinical and technical perspectives. The clinical importance of ICP monitoring is presented, and methods for ICP transduction are briefly discussed. These methods include intraventricular catheters, subarachnoid screws, epidural techniques, and the new fiberoptic ICP measurement systems. Approaches to the visual analysis of the ICP waveform are presented, with special emphasis on the relationship between the ICP waveform and the arterial blood pressure signal. Methods of computer-based ICP analysis are also reviewed, including histogram and systems analysis methods. Methods to predict ICP pressure rises and to estimate intracranial compliance are also discussed. Finally, ICP monitoring is reviewed from the point of view of patient outcome. It is concluded that advanced ICP waveform analysis methods warrant further clinical evaluation to demonstrate their clinical usefulness.     

中药注射剂不良反应监测的初步报告

目的 了解中药注射剂不良反应情况，探讨与不良反应的发生有关的影响因素。方法 采用医院集中监测方法，收集医院内所有使用中药注射剂的住院病人的临床资料和所有相关的不良事件，对不良反应因果关系进行判断，分析各种影响因素与不良反应发生的关系。结果 收集到3375例住院患者资料，发生与中药注射剂有关的不良事件共有51例，因果关系判断为“可能”者有11例，判断为“很可能”者有40例。与中药注射剂有关的可能不良反应的发生率为1．51％，92％的不良反应属于过敏反应。所监测的中药注射剂有31种，其中以鸦胆子油乳注射液、灯盏花素注射液和参附注射液的不良反应发生率较高。Logistic逐步回归分析表明，退休相对于体力劳动、较高的教育程度相对于文盲来说，不良反应发生的危险性较高。结论 中医内科病房住院病人中药注射剂不良反应的发生较少，但个别中药注射剂不良反应发生率较高，应引起注意。     

全身麻醉对小儿听性脑干反应测试结果的影响

目的　研究应用听性脑干反应 (auditorybrainstemreaction ,ABR)作为监测小儿全身麻醉深度与觉醒的客观指标。方法　选择听力正常的外科择期手术患儿 4 5例 ,按照美国麻醉学家学会表针分为Ⅰ～Ⅱ级 ,分别施行异丙酚静脉麻醉、芬太尼静脉麻醉及异氟醚吸入全身麻醉 ,随机每组 15例 ,应用丹麦Madsen诱发电位反应仪监测并记录麻醉各阶段ABR的Ⅰ、Ⅲ、Ⅴ波潜伏期及Ⅰ Ⅲ、Ⅲ Ⅴ、Ⅰ Ⅴ波间期 ,研究观察潜伏期和波间期随时间推移及麻醉剂量变化之间的关系 ,探讨ABR在异丙酚、芬太尼及异氟醚等不同麻醉中的表现特征和规律。结果　①异丙酚静脉麻醉和异氟醚吸入麻醉与剂量呈良好的正相关 ;②Ⅰ波的潜伏期特性对于控制麻醉深度极为重要 ;③Ⅴ波监测麻醉具有最佳的稳定性及相关性 ;④停用麻醉药一段时间或患儿基本清醒时 ,ABR各波潜伏期和波间期有的仍高于正常值 ,这是滞后 (延迟 )反应 ;⑤ABR对芬太尼术中的觉醒监测不太敏感。结论　ABR各波的潜伏期及波间期变化 ,可判断小儿全身麻醉深度 ,在一定程度上可作为判断觉醒的参考 ,但应考虑有延迟反应的可能     

中国的非小细胞肺癌Gefitinib分子靶向治疗

目的 探讨非小细胞肺癌gefitinib分子靶向治疗的国内经验。方法 收集国内7个医院未经正式发表的用gefitinib治疗晚期非小细胞肺癌的资料，重点分析广东省肺癌研究所的病例情况。结果 自2001年7月至2003年12月．共有282例晚期非小细胞肺癌接受gefitinib治疗。有效率为22．2％～47．7％，疾病控制率为62．6％～81．8％。没有观察到明显的毒副作用。结论 gefitinib可安全有效地用于国内的晚期非小细胞肺癌。