The donor line break cannula: effect on the donation process, blood component quality and transfusion microbiology testing of an important new blood bag safety feature.

BACKGROUND: The use of blood packs with an integral sampling system can result in anti-coagulant from the main bag reaching the sample pouch via the donor line, causing delayed coagulation of blood samples. In NHS Blood and Transplant, this has prevented the use of serum, the preferred matrix for transfusion microbiology (TM) testing, which has led to an increased false positive rate with ethylenediaminetetraacetic acid (EDTA) plasma. There is also a remote possibility of false negative results owing to sample dilution. Manufacturers have responded by offering packs with a donor line break cannula (DLBC) to prevent these adverse effects. OBJECTIVES: The aims of this study were to assess the impact of DLBC packs on donation, blood component quality and of the potential return to serum for TM testing. METHODS: DLBC packs from three manufacturers were assessed against control packs of the same dimensions and configuration. Donation duration, flow rate, platelet factor 4, prothrombin fragment 1+2, haemolysis and collection and processing incidents were compared. RESULTS: Results indicated no clinically significant adverse effect from the DLBC on the activation state of platelets, the coagulation cascade or increased haemolysis. Donation duration and blood collection and processing incident rates for DLBC packs were not significantly different to controls. CONCLUSIONS: The use of DLBC packs would reduce the complexity of manipulations during blood collection and therefore the likelihood of microbially contaminated donations (incorrect skin core diversion) and false negative TM tests. DLBC packs would enable the use of serum for TM testing with a significant reduction in false positive tests compared to EDTA plasma.

Blood pack fault monitoring.

BACKGROUND AND OBJECTIVES: The National Blood Service (NBS) has recalled blood components as a result of manufacturing faults, or defective blood pack component parts leading to the possibility of an 'open' system. There has been an increase in the complexity of blood packs as a result of leucodepletion, sample diversion and sampling. The NBS implemented a mechanism to collate and analyse blood pack faults as a safety and quality initiative in conjunction with blood pack manufacturers. MATERIALS AND METHODS: Standard reporting forms were produced and implemented at all Centres. The forms were collated and analysed using statistical analysis software. Control charts were used to identify trends for specific faults, which were resolved with the relevant manufacturer. RESULTS: The overall defect rate per million for the three main blood pack manufacturers used by the NBS for the respective periods 2001, 2002 and 2003, were as follows: Manufacturer A, 1076, 1396 and 954; Manufacturer B, 1496, 1301 and 2169; and Manufacturer C, 1871, 1253 and 1392. CONCLUSIONS: Monitoring and analysis of blood pack faults has resulted in the identification and rectification of specific problems associated with blood pack manufacture and use. Close collaboration with manufacturers has enabled effective remedial action. Wider collation of data would provide an early warning of potential areas of concern.

Emergence of item response modeling in instrument development and data analysis.

In summary, readers are encouraged to read carefully the IRT articles in this special issue. They provide theoretical as well as practical arguments in favor of using IRT models in the health outcomes measurement field. At the same time, readers should be aware that the IRT field is complex and software is limited and, in my judgment, not very user friendly (although some packages are better than others). In addition, sample sizes will often need to be larger than in classical measurement, at least with the more general IRT models, and applications are rarely straightforward. Considerable practical experience is needed to ensure successful applications of IRT in the development and validation of instruments for health outcomes measurement.

Reliability of proxy-reported and self-reported household appliance use.

Exposure assessment presents a major challenge for studies evaluating the association between household exposure to electric and magnetic fields and adverse health outcomes, especially the reliance on proxy respondents when study subjects themselves have died. We evaluated the reliability of proxy- and self-reported household appliance exposure. We recruited 92 healthy couples through either random-digit dialing or newspaper advertisements. Trained interviewers administered questionnaires to each member of a couple independently to assess the reliability of proxy-reported household appliance use. Eighty-five couples completed a second interview 2 months later to assess the reliability of self-reported appliance use. Reliability of proxy-reported appliance exposure was good when we inquired about having any exposure to each of the eight indicator appliances during the past year (range of kappa coefficients = 0.63-0.85; median = 0.76) but was lower with increased time to recall or increased detail. Reliability of self respondents reporting 2 months apart was excellent (range of kappa coefficients = 0.75-0.94; median = 0.87) for having any exposure to the eight indicator appliances during the past year, but reliability was again lower with increased detail. When we used self reports at the first interview as the standard, little systematic over- or underreporting occurred for proxy respondents or for self respondents reporting 2 months later. Because this study did not include cases of specific disease, these findings of no systematic differences in reporting do not refer to case or control status. In summary, reliability of self respondents' reports of appliance use is very good for recent time periods and good for broad aspects of exposure in distant time periods. Proxy respondents can provide information regarding broad aspects of appliance exposure in the past year, but detailed aspects of exposure or exposure in more distant time periods is not reliable.

Anesthetic effects of tiletamine-zolazepam, alone or in combination with butorphanol, in goats.

OBJECTIVE: To evaluate anesthetic effects of tiletamine-zolazepam (TZ), alone or in combination with butorphanol, in goats undergoing laparotomy for embryo collection. DESIGN: Randomized clinical trial with crossover design. ANIMALS: 9 adult female goats. PROCEDURE: Goats were anesthetized twice: once with TZ (5.5 mg/kg [2.5 mg/lb] of body weight, i.v.) and once with tiletamine-zolazepam and butorphanol (0.1 mg/kg [0.045 mg/lb], i.v.). Additional doses of TZ (0.5 to 1.0 mg/kg [0.23 to 0.45 mg/lb], i.v.] were administered as needed to maintain a surgical anesthetic plane. Time to sternal recumbency was recorded, and quality of induction was scored. Arterial pressures, heart rate, respiratory rate, and rectal temperature were recorded every 5 minutes; arterial blood samples were collected every 30 minutes. Oxygen was insufflated if estimated saturation of hemoglobin in peripheral arterial blood with oxygen was < 90%; intermittent positive-pressure ventilation was performed if goats became apneic. Muscle relaxation, quality of anesthesia, and eye signs were scored every 15 minutes during anesthesia. Anesthesia time was recorded, and quality of recovery and degree of postoperative analgesia were scored. Plasma cortiso concentration was measured before induction, immediately after extubation, and 2 hours after extubation. RESULTS: Induction was rapid and smooth. Five goats regurgitated, 3 required supplemental oxygen, and 1 required intermittent positive-pressure ventilation, but none of the goats became hypotensive. Muscle relaxation and quality of anesthesia were adequate. Goats recovered from anesthesia without complications. We did not detect any significant differences between anesthetic regimens for any of the variables measured, except bicarbonate concentration and base excess. CLINICAL IMPLICATIONS: TZ at a dose of 5.5 mg/kg was satisfactory for anesthetic induction in goats; additional doses can be given to extend anesthesia time, but addition of butorphanol at a dose of 0.1 mg/kg to this regimen does not seem to provide any measurable benefit. An oxygen source and a means of assisting ventilation should be available.

Development of the multidimensional index of life quality. A quality of life measure for cardiovascular disease.

OBJECTIVES: The purpose of this study was to design a multidimensional measure of health-related quality of life appropriate for patients with cardiovascular disease that was psychometrically sound, brief, and easy to administer. METHODS: Qualitative interviews conducted with healthy subjects and patients with cardiovascular diseases identified nine major quality of life domains. Based on the responses of 129 cardiovascular disease patients recruited from hospitals and clinics, a criterion-based approach was used to select 35 questionnaire items that best tapped these domains. Psychometric properties of the Multidimensional Index of Life Quality (MILQ) were tested with a sample of 348 patients with various cardiovascular diseases. RESULTS: Cronbach's alpha was 0.76 or higher for eight of the nine MILQ domains. Test-retest reliability coefficients were 0.73 or greater in all but two domains. Individual domain scores as well as a weighted overall quality of life index were correlated highly with self-assessed health and the number of heart-related symptoms. CONCLUSIONS: The Multidimensional Index of Life Quality is a psychometrically reliable and valid instrument for measuring quality of life in patients with cardiovascular diseases. The MILQ also may be a suitable measure for other types of chronic diseases.

Modelling aperture antennas in the near- and far-field regions using subarrays of equivalent uniformly illuminated apertures.

This paper develops and presents an application of Huygen's principle herein referred to as the equivalent uniformly illuminated aperture method (EUAM). This method is used to predict the E-field patterns of aperture antennas in both the near- and far-field regions. In applying this method the radiating aperture is mathematically replaced by an array of smaller, uniformly illuminated aperture sources. Thus the true aperture field is approximated in a step-wise manner by the individual sub-apertures that are uniformly illuminated by the field at the point on the aperture where the sub-aperture is located. This method is suitable for analysing any antenna if its aperture fields are known. Comparisons are made between this method, an equivalent dipole method, and experimental measurements. These calculations and measurements show that the EUAM is more accurate (especially in the near-field region), is much simpler to implement, and requires less execution time than the equivalent dipole method.

An investigation into information provided for patients on home parenteral nutrition.

A group of 34 patients who received home parenteral nutrition (HPN) were assessed by questionnaire to determine their knowledge of basic nutritional concepts, parenteral nutrition and the procedures used to monitor HPN. The results indicated that the HPN patients had an adequate knowledge of basic nutritional concepts and that this knowledge was not significantly different from that of 76 randomly selected control subjects. However, the HPN patients had significantly less understanding of parenteral nutrition and the procedures used to monitor HPN. Based on information obtained, a booklet was written to explain HPN to the same group of patients. Eighty-eight per cent of patients found the booklet either interesting or very interesting and 91% of patients reported that the booklet was read by other family members as well as themselves. Patients who had been on HPN for short periods of time learnt more from the booklet than other patients. Many patients would have appreciated more information about HPN when they first began treatment.

Development and application of the student test used in the School Health Education Evaluation.

To accurately assess the health knowledge, attitudes, and practices of students in grades four-seven, the staff of the School Health Education Evaluation (SHEE) project devoted extensive effort to identify a test appropriate for such assessment. An extensive literature review failed to produce an instrument sufficiently comprehensive or psychometrically sound that could be employed. In this paper, the philosophic orientation and the detailed processes followed in developing a noncurriculum specific, psychometrically sound evaluation instrument for use in the study is described. Included are the bases for the test framework, test objective development, test item review, the various measures constructed using the test blueprint, student performance on the test battery, the psychometric qualities of the test, and suggestions for appropriate use of the final test in other school health education settings.

T.S.T.--a new range of indicator devices for autoclaving processes.

Simple process indicators, usually relying on a colour change, are widely used as an aid to user assessment of the success or otherwise of autoclaving processes. Ideally, a process indicator should be capable of indicating not only that heating in steam has occurred but that heating has been maintained at a correct level for a suitable period of time. Furthermore, it would be preferable if any colour changes were abrupt rather than gradual throughout the period of heating.

A framework for viewing the process of standard setting.

The standard-setting literature is filled with contributions in which issues associated with standards are discussed and various methods for setting standards are presented and reviewed. Almost no attention has been given to guidelines for helping standard-setting groups or committees address the issues and technical matters that arise in selecting and implementing a standard-setting method and finally setting a standard (or standards). This article was prepared to describe sets of context-setting variables and technical matters associated with standard-setting to assist groups or committees desiring to set standards in a systematic way.

Evaluation of a prototype micro-electronic autoclave cycle integrator.

Instability and non-uniformity of spore preparations and the non-conformity of chemical indicators to the temperature coefficients of spore inactivation are problems associated with current methods of autoclave cycle monitoring. A prototype micro-electronic instrument, which largely overcomes these problems, is described. It monitors autoclave cycles in terms of the integral F0 and Nabla functions. Its thermometric and integrating accuracy is demonstrated. A discussion of the problems associated with the use of sensitive electronic instruments in the autoclave room environment reveals the need for independent monitoring areas when such devices are used. Inactivation constants were determined for spores of the organism Bacillus stearothermophilus, NCTC 10 003 and were described using D115 (12.0 min) and Z (9.0 degrees C) values and the first order reaction Arrhenius constants A 10(41.2) min-1) and Ea (74.4 kcal mol-1, 311 kJ mol-1). These have been compared with recently published values. The standardization of F0 and Nabla is discussed with reference to the setting of minimum values related to product bioburden and maximum values related to an acceptable degree of product degradation.

Supply, need, and distribution of anesthesiologists and nurse anesthetists in the U.S., 1972 and 1980.

This paper examines the relationship between problems in anesthesia care delivery and the availability and utilization of trained anesthesia manpower. The 1972 and 1980 projected supply and mix of anesthesiologists and nurse anesthestists is described and compared to the current and projected need for their services. The need estimates developed for anesthesia manpower are based upon published data on operations, productivity and theoretical team configurations. Utilization data are used since they are quantifiable and the need for anesthesia services is, indeed, supply-induced. Two estimates of need are developed based upon differing degrees to which anesthesia teams can be effectively employed, this being contingent upon the size of the hospital operative workload. While the need estimates developed for anesthesiologists for 1972 and 1980 were fairly close in aggregate number to the actual and projected supply; the need estimates for nurse anesthetists fell far short of their 1972 and 1980 projected supply. The 1972 need estimates are then compared on a statewide basis to the actual supply and mix of anesthesia personnel to reveal a severe maldistribution which is quantified in terms of shortage and execesses of anesthesiologists and nurse anesthetists for each state.