Measurement of cardiac output-transtracheal Doppler versus thermodilution

The ABCOM 1 transtracheal Doppler (TTD) has been developed as a non-invasive cardiac output monitor. With this device, cardiac output is continuously calculated from ascending aortic blood flow velocity and aortic diameter obtained via an ultrasound transducer incorporated into the tip of an endotracheal tube. We evaluated the clinical use of the ABCOM 1 monitor and compared cardiac outputs obtained using the TTD system with simultaneous thermodilution (TD) measurements. We found the operation of the ABCOM 1 monitor to be difficult and time-consuming. In our operating rooms, acceptable Doppler signal quality was difficult to obtain. There was no correlation between 36 simultaneously obtained TTD and TD cardiac output measurements. The average difference between measurement techniques and the limits of agreement were unacceptably large (mean difference = 3.04 L.min-1, mean +/- 2 SD = -6.04 to 12.48 L.min-1). Separately analyzing only those measurements during which Doppler signal quality was adequate did not improve agreement between TTD and TD measurements. On the basis of these findings, TTD cannot be recommended as a clinical cardiac output measurement technique.     

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.     

Risk assessment in clinical pharmacy

Medication error forms a major proportion of the errors in the medical system. Despite many studies of adverse drug events, there are no systematic ways of ensuring safety, or of assessing how safe a pharmaceutical system is. Risk assessment is required in hazardous industries such as nuclear power or oil and gas. Risk assessments involve identifying the defences and assessing their effectiveness and are relatively uncommon in clinical pharmacy , as opposed to reactive approaches involving incident analyses. Risk factors, that degrade barriers, can be identified and their effect measured. A risk assessment structure for pharmacy processes is proposed that can also be used to support incident investigation and analysis processes and provide a standard for audit.     

放射治疗中的摆位误差

随着放射治疗向高精度方向发展 ,研究放射治疗中的摆位误差具有重要意义。就摆位误差的定义、来源、表示方法、测量予以综述 ,并总结了以往的研究数据 ,提出临床工作中需注意的问题。     

PATHOLOGY OF LONG-CHAIN 3-HYDROXYACYL-COA DEHYDROGENASE DEFICIENCY CAUSED BY THE G1528C MUTATION

Long-chain 3-hydroxyacyl-CoA dehydrogenase deficiency is a recently discovered disorder affecting the mitochondrial-oxidation of fatty acids. There have been few reports of the pathologic findings in-oxidation defects. We examined pathologic specimens from 16 patients with this disorder (11 patients were homozygous for the common mutation G1528C, 5 patients were siblings with a similar clinical presentation). Autopsies were performed on all 15 patients who died, and liver biopsy specimens were available from 8 patients. Hepatomegaly and steatosis of the liver, found in every patient, were often combined with fibrosis or cirrhosis. Cardiomegaly and accumulation of fat in the myocardium, renal tubules, and skeletal muscle were found in many patients. A detailed neuropathologic examination was performed on six patients, and brain specimens obtained at autopsy were examined in four others. In general, neuropathologic findings were mild and unspecific, but vacuolization was detected in the deep gray matter and in the cerebellum and brain stem nuclei of five patients. In one patient the vacuolization was prominent; in the other four it was milder and more focal. The vacuoles seemed to be either in the neuropil or associated with swollen hydropic cells. The uniform pattern of histopathologic changes facilitates the diagnostics in this severe disorder, allowing opportunities for therapy and prenatal diagnosis.     

SOMATOM PLUS 4 CT NVRAM故障的排除

文章分析了SOMATOM PLUS 4的NVRAM故障原因,并介绍了该故障的排除方法.     

Measurement Issues in Health Disparities Research

Background. Racial and ethnic disparities in health and health care have been documented; the elimination of such disparities is currently part of a national agenda. In order to meet this national objective, it is necessary that measures identify accurately the true prevalence of the construct of interest across diverse groups. Measurement error might lead to biased results, e.g., estimates of prevalence, magnitude of risks, and differences in mean scores. Addressing measurement issues in the assessment of health status may contribute to a better understanding of health issues in cross-cultural research.
Objective. To provide a brief overview of issues regarding measurement in diverse populations.
Findings. Approaches used to assess the magnitude and nature of bias in measures when applied to diverse groups include qualitative analyses, classic psychometric studies, as well as more modern psychometric methods. These approaches should be applied sequentially, and/or iteratively during the development of measures.
Conclusions. Investigators performing comparative studies face the challenge of addressing measurement equivalence, crucial for obtaining accurate results in cross-cultural comparisons.     

Closed loop control of anaesthesia: an assessment of the bispectral index as the target of control

We investigated the performance of a closed-loop system for administration of general anaesthesia, using the bispectral index as a target for control. One hundred patients undergoing gynaecological or general surgery were studied. In 60 patients, anaesthesia was maintained by intravenous infusion of a propofol/alfentanil mixture. In 40, an isoflurane/nitrous oxide based technique was used. For each technique, patients were randomly allocated to receive either closed-loop or manually controlled administration of the relevant agents (propofol/alfentanil or isoflurane), with an intra-operative target bispectral index of 50 in all cases. Closed-loop and manually controlled administration of anaesthesia resulted in similar intra-operative conditions and initial recovery characteristics. During maintenance of anaesthesia, cardiovascular and electro-encephalographic variables did not differ between closed-loop and manual control groups and deviation of bispectral index from the target value was similar. Intra-operative concentrations of propofol, alfentanil and isoflurane were within normal clinical ranges. Episodes of light anaesthesia were more common in the closed-loop group for patients receiving propofol/alfentanil anaesthesia and in the manual group for patients receiving isoflurane/nitrous oxide anaesthesia. Convenience aside, the closed-loop system showed no clinical advantage over conventional, manually adjusted techniques of anaesthetic administration.     

School vision screening, ages 5–16 years: the evidence-base for content, provision and efficacy

The optometric profession in the UK has a major role in the detection, assessment and management of ocular anomalies in children between 5 and 16 years of age. The role complements a variety of associated screening services provided across several health care sectors. The review examines the evidence-base for the content, provision and efficacy of these screening services in terms of the prevalence of anomalies such as refractive error, amblyopia, binocular vision and colour vision and considers the consequences of their curtailment. Vision screening must focus on pre-school children if the aim of the screening is to detect and treat conditions that may lead to amblyopia, whereas if the aim is to detect and correct significant refractive errors (not likely to lead to amblyopia) then it would be expedient for the optometric profession to act as the major provider of refractive (and colour vision) screening at 5-6 years of age. Myopia is the refractive error most likely to develop during primary school presenting typically between 8 and 12 years of age, thus screening at entry to secondary school is warranted. Given the inevitable restriction on resources for health care, establishing screening at 5 and 11 years of age, with exclusion of any subsequent screening, is the preferred option.