Transthoracic defibrillation: does electrode adhesive pad position alter transthoracic impedance?

AIMS: To determine the prevalence of isolated systolic hypertension (ISH) in patients 60 years of age and over attending general practitioners, and the proportion of patients in whom blood pressure (BP) remains within the ISH range when measured on three successive occasions and when using home BP monitoring. METHODS: BP was measured in 38 832 patients. Patients categorized as having ISH were reviewed after one week. Patients who had BPs in the ISH range at the second visit were provided with a home BP monitor and attended again in one week's time for further clinic blood pressure measurements. RESULTS: 8.6% of all patients were classified as having ISH and 31.4% as having borderline ISH at the first clinic visit. ISH was twice as prevalent in patients receiving antihypertensive therapy (12.4%) than in those not on antihypertensive therapy (6.2%). Of the patients initially categorized as having ISH, and who attended all three clinic visits and completed the home BP monitoring, 52.3% were confirmed as having ISH, 34.0% fell into the borderline ISH range and only 7.0% had a normal BP reading at the third clinic visit. The use of home BP monitoring produced similar results. CONCLUSION: ISH is present on first screening in approximately 8% of elderly Australian patients. This prevalence falls by about 50% when BP is measured on two further occasions, with most patients subsequently falling into the borderline ISH range. Home BP monitoring does not reduce the percentage of patients classified as having ISH on the basis of three clinic measurements.     

A comparison of transhiatal and transthoracic resection for oesophageal carcinoma

We compared the results of 327 transthoracic (TT) resections and 82 transhiatal (TH) resections for carcinoma of the oesophagus operated on between July 1982 and June 1991. Significantly more patients with carcinoma of the lower third of the oesophagus (54% versus 28%) and with increased pulmonary risks for surgery (61% versus 22%) were selected for the TH approach as compared with the TT approach. Results showed comparable intraoperative complications between the two groups. 5% of patients in the TH group required a thoracotomy for control of haemorrhage (3 patients) and repair of bronchial tear (1 patient) which occurred during the transmediastinal dissection. Postoperatively, mechanical ventilation requirement and complications involving the cardio-pulmonary systems were similar between the two groups. Anastomotic leakage occurred in 3% and 4%, respectively for the TH and TT patients (p = NS), whereas hoarseness occurred in 16% and 5%, respectively (p = 0.001). The 30-day mortality rates and hospital mortality rates were comparable between the two groups as were the overall survival rates. Our results suggested that while TH resection did not diminish the operative morbidity and mortality rates overall, it is appropriate for patients with increased pulmonary risks to be preferentially selected for this approach, and for tumours located in the upper and lower portion of the thoracic oesophagus where dissection of the tumour can be carried out mostly under vision.     

Relative efficacy of monophasic and biphasic waveforms for transthoracic defibrillation after short and long durations of ventricular fibrillation

BACKGROUND: Recently, interest has arisen in using biphasic waveforms for external defibrillation. Little work has been done, however, in measuring transthoracic defibrillation efficacy after long periods of ventricular fibrillation. In protocol 1, we compared the efficacy of a quasi-sinusoidal biphasic waveform (QSBW), a truncated exponential biphasic waveform (TEBW), and a critically damped sinusoidal monophasic waveform (CDSMW) after 15 seconds of fibrillation. In protocol 2, we compared the efficacy of the more efficacious biphasic waveform from protocol 1, QSBW, with CDSMW after 15 seconds and 5 minutes of fibrillation. METHODS AND RESULTS: In protocol 1, 50% success levels, ED50, were measured after 15 seconds of fibrillation for the 3 waveforms in 6 dogs. In protocol 2, defibrillation thresholds were measured for QSBW and CDSMW after 15 seconds of fibrillation and after 3 minutes of unsupported fibrillation followed by 2 minutes of fibrillation with femoral-femoral cross-circulation. In protocol 1, QSBW had a lower ED50, 16.0+/-4.9 J, than TEBW, 20.3+/-4.4 J, or CDSMW, 27.4+/-6.0 J. In protocol 2, QSBW had a lower defibrillation threshold after 15 seconds, 38+/-10 J, and after 5 minutes, 41.5+/-5 J, than CDSMW after 15 seconds, 54+/-19 J, and 5 minutes, 80+/-30 J, of fibrillation. The defibrillation threshold remained statistically the same for QSBW for the 2 fibrillation durations but rose significantly for CDSMW. CONCLUSIONS: In this animal model of sudden death and resuscitation, these 2 biphasic waveforms are more efficacious than the CDSMW at short durations of fibrillation. Furthermore, the QSBW is even more efficacious than the CDSMW at longer durations of fibrillation.     

Assessment of atrial septal defect morphology by transthoracic three dimensional echocardiography using standard grey scale and Doppler myocardial imaging techniques: comparison with magnetic resonance imaging and intraoperative findings

The properties of chemically cured and light-cured composite resins were recorded at baseline and at intervals over seven years, while the materials were exposed to controlled storage conditions as well as to various conditions typical of clinical situations. For chemically cured resins in clinical conditions, mechanical properties decreased, and working and setting times increased over four years; if refrigerated (controlled), properties remained constant past seven years. For light-cured resins, test results were constant over the entire seven-year test period regardless of storage conditions. An accelerated aging protocol was developed to allow for the evaluation of the relative storage stability of new and similar materials.     

A comparison of focused and standard cognitive therapy for panic disorder

A set of measures assessing abilities related to legal standards for competence in the adjudicative process were administered to mentally-disordered criminal defendants with diagnoses of schizophrenia, affective disorder, other psychiatric disorders, and to criminal defendants without diagnosed mental disorder. Mentally-disordered defendants were recruited from two groups: those who had been committed for restoration of competence and those who had been identified by jail personnel as mentally ill. Significant impairments in competence-related abilities were found for approximately half of the defendants with schizophrenia. Defendants with schizophrenia scored lower on measures of understanding, reasoning, and appreciation related to the adjudication process. The association between symptoms and competence-related abilities was explored within diagnostic groups. Conceptual disorganization was found to be inversely correlated with performance on all measures in both defendants with schizophrenia and those with affective disorders. For other psychotic symptoms, differing patterns of correlations were found in the two major diagnostic groups. The implications for policy designed to safeguard the rights of defendants to be tried while competent are discussed.     

A comparison of a token economy with standard inpatient treatment.

Used the Nurses Observation Scale for Inpatient Evaluation (NOSIE-30) to evaluate a token economy ward at a large psychiatric hospital in comparison with 3 nontoken wards in the same unit. The token economy appeared to be more effective in generating a broad range of behavior changes, including both an increase in positive behaviors and a decrease in negative behaviors. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A standard test of heat-pain responses using CASE IV

Heat-pain threshold and stimulus response characteristics can be evaluated with graduated heating pulses from a radiant heat source or a contact thermode. Results may be used to: (1) evaluate differences in sensation among anatomical sites, sides of the body, and with development and aging; and (2) provide an end-point for the study of the efficacy of drugs; or to follow the course of sensory alteration in disease (medical practice, epidemiologic studies, and controlled clinical trials). Because there is great variability in how tests of this kind are performed and scored, comparisons of results among medical centers are difficult. To meet this need, we have developed, and here describe, a standardized and validated test of heat-pain. We use both pyramidal and trapezoid-shaped stimuli. The range of stimulus magnitudes we recommend is sufficient to test heat-pain at a sensitive region (the face) of young people and an insensitive region (the foot) of healthy old people. From tests on healthy subjects and patients, we find that neither our previously published forced-choice or 4, 2, and 1 stepping algorithms are suitable for testing heat-pain sensation. We, therefore, introduce the Non-Repeating Ascending with Null Stimuli (NRA-NS) algorithm which performs satisfactorily. The graphed data points of responses to increasingly stronger heat pulses were made up of two components-the no pain (0) response line and the heat-pain response line (> or = 1 numerical scaling of the pain responses graded from 1 [least] to 10 [greatest]). For the pain responses, we found that usually a curve could be fit using a quadratic equation. Using this equation, or interpolation where necessary, it is possible to compute the heat-pain detection threshold (HPDT or HP:0.5), an intermediate heat-pain response (HP:5.0), and the difference between the two (HP:5.0-0.5). Our studies show that a certain time is needed between successive stimuli and tests to minimize changing basal skin temperature or threshold. We also demonstrated that low or high baseline skin temperatures can affect heat-pain responses, therefore, we advocate specific testing conditions. Based on a study of 25 healthy subjects, the reproducibility of the test falls within +/-1 stimulus steps 88% of the time for HP:5.0 and 76% of the time for HP:0.5. The precise approaches employed to make the test standard and reproducible are described. We illustrate that the algorithm and testing system is able to document altered pain threshold with skin abrasion, with intradermal injection of nerve growth factor, and with diabetic polyneuropathy.     

A comparison of transesophageal and transthoracic echocardiographic assessment of left ventricular function in pediatric patients with congenital heart disease

OBJECTIVE: To determine the quantitative utility of transesophageal echocardiographic assessments of left ventricular function in pediatric patients with congenital heart disease by evaluating the variability between observers and between echocardiographic windows. DESIGN: Retrospective, blinded analysis. SETTING: University-associated pediatric hospital. PARTICIPANTS: Transthoracic and transesophageal echocardiographic images of 25 pediatric patients with congenital heart disease were reviewed. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: End-diastolic area, end-systolic area, and fractional area change were measured from short-axis images of the left ventricle at the midpapillary level by two separate investigators. These measurements were compared by the method of Bland and Altman and Sheiner and Beal. Significant differences in measurements of end-diastolic and end-systolic area by different observers were noted, but they were systematic. A similar situation was noted for the comparison of transthoracic and transesophageal measurements of end-diastolic and end-systolic area. In the comparison of fractional area change between observers or windows, bias and absolute prediction error were lower, with 95% confidence limits of bias or absolute prediction error of 10% or less. CONCLUSIONS: The potential error in the measurement of fractional area change in 10% under optimal conditions. This would suggest that the assessment of ventricular function in the operating room or intensive care unit, under less than optimal conditions, should be viewed as a qualitative, rather quantitative, measurement. There may be significant interobserver and interwindow variability.     

A comparison of hemodynamic parameters derived from transthoracic electrical bioimpedance with those parameters obtained by thermodilution and ventricular angiography

OBJECTIVE: To determine the limits of agreement between the cardiac output and volumetric data estimated by impedance cardiography with the cardiac output determined by thermodilution and the left ventricular ejection fraction and end-diastolic volume estimated from left ventriculography. DESIGN: A prospective study. SETTING: The cardiac catheterization laboratory of a university-affiliated teaching hospital. PATIENTS: Twenty-four patients with coronary artery disease undergoing elective left- and right heart catheterization. INTERVENTIONS: Cardiac output was measured by the thermodilution method and the ejection fraction and left ventricular volumetric data were determined by ventriculography. These same measurements were obtained by simultaneously performed impedance cardiography using a commercially available bioimpedance device. MEASUREMENTS AND MAIN RESULTS: The patients' mean cardiac output was 4.6 +/- 1.7 L/min by bioimpedance and 5.0 +/- 1.1 L/min by thermodilution. The limits of agreement between the two methods was -4.1 to 3.5 L/min. The 95% confidence intervals for the lower and upper limits of agreement were -2.7 to -5.5 L/min and 2.1 to 4.9 L/min, respectively. The mean ejection fraction was 63 +/- 8% by bioimpedance and 53 +/- 15% by ventriculography. The limits of agreement between the ejection fraction estimated by bioimpedance and ventriculography was -35% to 37%. The 95% confidence intervals for the lower and upper limits of agreement were -22% to -48% and 24% to 50%, respectively. The mean left ventricular end-diastolic volume was 108 +/- 47 mL, as estimated by bioimpedance, and 121 +/- 35 mL, as estimated by ventriculography. The limits of agreement between the left ventricular end-diastolic volume as estimated by bioimpedance and ventriculography was -139 to 113 mL. The 95% confidence intervals for the lower and upper limits of agreement were -184 to -94 mL and 68 to 158 mL, respectively. CONCLUSIONS: The 95% confidence range defining the limits of agreement between cardiac output and volumetric data estimated by bioimpedance, with the cardiac output measurement by thermodilution and the volumetric data estimated from left ventriculography, were wide, making the degree of agreement clinically unacceptable. In the opinion of the authors, impedance cardiography should not replace invasive hemodynamic monitoring at this time.     

Low-energy endocardial defibrillation using dual, triple, and quadruple electrode systems

The feasibility of achieving both universal application of nonthoracotomy leads and low (< or = 15 J) defibrillation energy requirements by optimizing lead system configuration for use with low-output (<30 J) biphasic shock pulse generators was examined. Sixteen patients (mean age 62 +/- 8 years and mean left ventricular ejection fraction of 38 +/- 15%) were included in the study. All patients had either experienced syncope with induced ventricular tachycardia (n = 4) or had documented sustained ventricular tachycardia (n = 7) or ventricular fibrillation (n = 5). Defibrillation threshold testing was performed in 2 stages on different days in these patients. In the first stage, 2 defibrillation catheter electrodes were positioned in the right ventricle and superior vena cava with an axillary cutaneous patch. Fifteen-joule, 10- and 5-J biphasic shocks were delivered across 3 different electrode configurations-right ventricle to superior vena cava, right ventricle to axillary patch, right ventricle to a combination of superior vena cava and axillary patch. In the second stage, an 80-ml can electrode was added subcutaneously in a pectoral location to the previous leads. Configurations compared were the right ventricle to pectoral can, and right ventricle to an "array"-combining superior vena cava, can, and axillary patch leads. The defibrillation threshold was determined using a step-down method. In stage 1, mean defibrillation threshold for the right ventricle to axillary patch (12.7 +/- 5.9 J) and right ventricle to superior vena cava plus axillary patch (9.8 +/- 5.2 J) configurations was lower than the right ventricle to superior vena cava configuration (14.2 +/- 6.4 J, p <0.05). In stage 2, the defibrillation was higher for the right ventricle to pectoral can (9.2 +/- 5.1 J) configuration compared with the right ventricle to the array (5.6 +/- 3.6 J, p < or =0.05). The right ventricle to array had the lowest defibrillation threshold, whereas the right ventricle to pectoral can was the best dual electrode system. Low-energy endocardial defibrillation (< or =10 J) was feasible in 72% of tested patients with > 1 electrode configuration at 10 J, whereas only 53% of successful patients could be reverted at >1 electrode configuration at 5 J (p <0.05). Reduction in maximum pulse generator output to < or =25 J using these electrode configurations with bidirectional shocks is feasible and maintains an adequate safety margin.     

A biophysical model for defibrillation of cardiac tissue

We propose a new model for electrical activity of cardiac tissue that incorporates the effects of cellular microstructure. As such, this model provides insight into the mechanism of direct stimulation and defibrillation of cardiac tissue after injection of large currents. To illustrate the usefulness of the model, numerical stimulations are used to show the difference between successful and unsuccessful defibrillation of large pieces of tissue.     

Predicting the leakage performance of small bodyworn disposable incontinence pads using laboratory tests

An international multi-centre project has been run to create an international standard for measuring the leakage performance of small, disposable incontinence pads for lightly incontinent women. One hundred and thirteen women tested batches of nine different incontinence pads of widely differing designs and noted the severity with which each individual used pad had leaked so that leakage performance could be determined as a function of urine weight. In addition, testers rated the overall leakage performance of each of the nine products on a five-point scale. These clinical data were compared with laboratory data from 153 different pad measurements, each of which was evaluated by seeing how well the data it yielded correlated with the clinical test data. A wetback test emerged as the clear winner. It usually predicted the clinical leakage performance of pads to an accuracy of +/- 10%. It involved applying 25 ml of 1% w/v saline to a pad and measuring how much escaped into a filter paper held against the wet pad for 1 min under a pressure of 1.5 kPa. Pads which released the least test fluid into the filter paper leaked least in the user tests. The method will be published as an ISO standard during 1997.     

Parent-child interaction therapy: A comparison of standard and abbreviated treatments for oppositional defiant preschoolers.

Families of 54 behaviorally disturbed preschool-aged children (3 to 5 years) were randomly assigned to 1 of 3 treatment conditions: standard parent-child interaction therapy (PCIT; STD); modified PCIT that used didactic videotapes, telephone consultations, and face-to-face sessions to abbreviate treatment, and a no-treatment waitlist control group (WL). Twenty-one nondisturbed preschoolers were recruited as a social validation comparison condition. Posttreatment assessment indicated significant differences in parent-reported externalizing behavior in children, and parental stress and discipline practices from both treatment groups on most measures compared with the WL group. Clinical significance testing suggested a superior effect for the STD immediately after intervention, but by 6-month follow-up, the two groups were comparable. The findings indicate that abbreviated PCIT may be of benefit for families with young conduct problem children. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Cost-effectiveness comparison of sequential ofloxacin versus standard switch therapy

OBJECTIVE: To compare the cost-effectiveness of sequential intravenous-to-oral ofloxacin versus intravenous-to-oral standard switch therapy for the treatment of patients with sepsis who are hospitalized with bacterial infections. DESIGN: Cost-effectiveness analysis from a provider perspective, including resources important to an integrated healthcare network, of a randomized, open-label, controlled, clinical trial. SETTING: Millard Fillmore Health System, Buffalo, NY. PATIENTS: Hospitalized adults requiring parenteral antibiotics for a complicated urinary tract infection, lower respiratory tract infection, or skin and soft tissue infection. INTERVENTIONS: Sequential intravenous-to-oral ofloxacin or standard intravenous-to-oral switch antibiotics. OUTCOME MEASURES: Clinical outcomes and direct costs associated with hospitalization, primary physician services, specialist physician services, and outpatient care. RESULTS: Eighty-two of 89 patients randomized into the two treatment groups were evaluable. Standard switch therapy failed with 12 patients versus 10 patients receiving ofloxacin. Complete economic data were available for 74 patients. Sequential ofloxacin therapy resulted in a 1-day-shorter antibiotic-related hospitalization without evidence of recurrent infection during the posttherapy follow-up evaluations. An average cost savings of $399 per patient was achieved in the sequential ofloxacin group. Although this difference did not attain statistical significance (probably due to the large variance), it is an economically significant finding. The cost-effectiveness ratios were $5735 per successful outcome for the standard switch therapy group versus $5126 per successful outcome in the sequential ofloxacin group. CONCLUSIONS: Sequential ofloxacin was as effective and consistently less expensive than standard switch antibiotics in the initial evaluation and in the sensitivity analysis of room cost and drug acquisition cost. Standard switch therapy would have to be greater than 25% more effective than sequential ofloxacin therapy to change the economic decision.     

A comparison of three methods of estimating the standard deviation of performance in dollars.

196 supervisors in a national convenience store organization were asked to make the ratings needed to estimate standard deviation of performance in dollars (SDD), using (1) the method suggested by F. L. Schmidt et al (see record 1981-02231-001), (2) the CREPID procedure outlined by W. F. Cascio (1982), and (3) the 40% rule, suggested as an alternative by F. L. Schmidt et al (see record 1982-29165-001). Results show that Methods 2 and 3 produced comparable results. The SDD derived from Method 1 was 1.8 times as large as that produced by Method 2. (8 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A comparison of temperature measurements using three ear thermometers

Following anecdotal and research-based reports of inaccuracies encountered with the use of ear thermometers in patient care settings, this two-phase study was designed to compare the accuracy of three ear thermometers when used in a multioperator environment. The within-subject variation (limits of agreement) in ear temperature measurements obtained with the three ear thermometers in a multioperator condition by using an oral temperature reference standard ranged from +/- 1.25 degrees F to 1.85 degrees F. In multioperator, multisubject patient care environments using a pulmonary artery catheter core temperature as the reference standard, the limits of agreement for ear temperature measurements obtained with the three different ear thermometers ranged from +/- 2.19 degrees F to 2.85 degrees F. These results suggest that there is substantial variation in ear measurements and raise questions about the use of ear thermometers when there are multiple personnel taking temperatures, as occurs in hospital-based clinical practice environments. Handedness of the operator, position of the patient, and the ear used for measurement did not produce clinically significant variability in ear temperature measurements.     

选择和使用冶金标准样品的原则

冶金分析工作者应根据采用的分析方法和被测冶金样品的具体情况选用合适的冶金标准样品,根据需要选择合适的冶金标准样品之后,正确地使用及贮存冶金标准样品也是使用者应注意的问题.正确使用冶金标准样品可提高测定数据的可靠性,并促进冶金分析的发展.     

中美锅炉钢板标准的对比及发展

锅炉钢板是锅炉制造中非常关键的材料之一。超临界火电机组锅炉的发展,对锅炉钢板的性能提出了更高的要求。锅炉新材料的应用是由材料标准作为载体而实施的。对比分析我国标准与美国ASME材料标准之间存在的差距,制定适合我国火电机组发展的先进的锅炉钢板标准,应是发展方向。