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Biomedical subjects

B Kirwan

Publications and source records attributed to B Kirwan.

7 recordsLinked to original sources
PubMed2000

Soft systems, hard lessons.

This paper is concerned with practical experiences of achieving human factors and safety interventions in the nuclear power and process control industries. It rests upon the premise that, although human factors (HF) and safety may be technological in approach, they nevertheless must operate in a socio-technical environment, within companies with corporate structures and cultures, interacting with regulatory authorities. A crucial ingredient to the successful implementation and integration of human factors into company practices and procedures is therefore the nature of the inter-relationships between human factors personnel and those who control the existing procedures determining all aspects of the design and operational processes. Such inter-relationships can largely determine whether HF is implemented or not. These human-human interactions and interfaces in a socio-technical system may be referred to as soft systems. When training in human factors, much of the training is concerned with technical aspects of the discipline. However, when entering industry or consultancy, one quickly discovers that technical aspects are usually the least of one's problems. This paper is concerned with experiences and guidance to better help the human factors professional starting out in industry. There is little scientific method in the paper. It is, instead, a distillation of this author's and others' experiences in acting either as a practitioner or consultant, or as leader of a human factors unit in industries that have at times been reluctant or even hostile about the perceived 'invasion' of human factors. However, to avoid being purely anecdotal, the experiences are placed in a framework concerned with the life cycle of integrating human factors into an industry, from being the first HF person in a company, to the development of a successful unit, or the absorption of a successful unit into other departments. Within this framework a range of strategic aspects are dealt with, such as integration of HF into the design process, and selection of test-case projects.

Communication↗
PubMed1999

Left ventricular remodelling in post-myocardial infarction patients with left ventricular ejection fraction 40-50% vs 25-39%. Influence of nisoldipine treatment? An echocardiographic substudy from the DEFIANT II study.

OBJECTIVE: Left ventricular (LV) remodelling following acute myocardial infarction has generally been studied in patients with LV ejection fraction (EF) < 40%, and it has been shown that this process can be attenuated by ACE inhibitors. Little is known regarding LV remodelling in patients with LVEF > or = 40% or the effects of treatment in this patient cohort. The DEFIANT II study (Doppler Flow and Echocardiography in Functional cardiac insufficiency) included 542 post-infarction patients with LVEF 25-50% without overt heart failure within 13 days following acute myocardial infarction (AMI). They were then randomized to nisoldipine coat-core (CC) or placebo and followed up for 6 months. DESIGN: Two-dimensional echoes were obtained after 8 (5-13) days and 6 months following AMI. SETTING: LV end diastolic (ED) and end systolic (ES) volumes (V) were calculated in 503 patients with technically satisfactory paired echoes using the biplabe method of discs in a core laboratory. SUBJECTS: Group A. 217 patients with baseline EF 40-50%, of whom 112 were randomized to nisoldipine and 104 to placebo (one patient was taken off study medication). Group B. 286 patients with EF 25-39%, of whom 145 were randomized to nisoldipine and 141 to placebo. RESULTS: LVEDV was 175 (+/-45) ml in Group A vs 203 (+/-49) ml in Group B (p = 0.001) at baseline and 184 (+/-48) ml vs 213 (+/-56) ml (p = 0.001), respectively, at 6 months. LVESV at baseline was 97 (+/-42) ml in Group A vs 133 (+/-37) ml in Group B (p = 0.001), and 106 (+/-34) ml vs 134 (+/-45) ml (p = 0.001) at 6 months, respectively. The increase of LVESV was 9 (+/-29) ml in Group A vs 2 (+/-35) ml in Group B (p = 0.007). LVEF decreased by 2 (+/-6)% in Group A vs an increase of 3 (+/-6)% in Group B (p = 0.001). Treatment with nisoldipine had no influence on LV volumes in either of the two groups or in the total study group. CONCLUSION: LV dilatation 6 months following AMI in patients with EF 40-50% was similar in end diastole, but more pronounced in end systole vs patients with EF 25-39%. LV remodelling did not change significantly after nisoldipine treatment.

Adult↗
PubMed1998

Human error identification techniques for risk assessment of high risk systems--Part 1: Review and evaluation of techniques.

This is the first in a two-part series of papers dealing with the area of assessing human errors in high risk complex systems. This first paper outlines thirty-eight approaches of error identification, categorising them into types of error identification approach. The paper then reviews these techniques with respect to a broad range of criteria. Viable and non-viable techniques are identified. Trends and research needs are also noted. The second paper proposes a framework or tool-kit approach to Human Error Identification, and presents a prototype methodology to show what such a framework approach would look like in practice, for the nuclear power domain.

Ergometry↗
PubMed1998

Human error identification techniques for risk assessment of high risk systems--part 2: towards a framework approach.

This is the second paper in a series of two, reviewing human error identification approaches for risk assessment of high risk socio-technical systems. The previous paper identified and reviewed thirty-eight techniques. One of the closing comments was that no single technique sufficed for all the practitioner's needs, and that a potential way forward was to utilise a number of techniques in a toolkit fashion, or to develop a new framework-based or toolkit-based approach. This paper therefore describes in detail a framework approach developed for the UK nuclear power and reprocessing industry, showing the practical implementation of such a system. It then considers some of the advantages and disadvantages of such framework approaches. The paper also discusses some of the relationships between error identification and Ergonomics.

Ergonomics↗
PubMed1997

The validation of three human reliability quantification techniques--THERP, HEART and JHEDI: Part II--Results of validation exercise.

This is the second of three papers dealing with the validation of three Human Reliability Assessment (HRA) techniques. The first paper introduced the need for validation, the techniques themselves and pertinent validation issues. This second paper details the results of the validation study carried out on the Human Reliability Quantification techniques THERP, HEART and JHEDI. The validation study used 30 real Human Error Probabilities (HEPs) and 30 active Human Reliability Assessment (HRA) assessors, 10 per technique. The results were that 23 of the assessors showed a significant correlation between their estimates and the real HEPs, supporting the predictive accuracy of the techniques. Overall precision showed 72% (60-87%) of all HEPs to be within a factor of 10 of the true HEPs, with 38% of all estimates being within a factor of three of the true values. Techniques also tended to be pessimistic rather than optimistic, when they were imprecise. These results lend support to the empirical validity of these three approaches.

Benchmarking↗
PubMed1997

The validation of three human reliability quantification techniques--THERP, HEART and JHEDI: Part III--Practical aspects of the usage of the techniques.

This is the third paper in a series of three dealing with the detailed investigation of the empirical validity of three human reliability assessment (HRA) techniques. The first paper introduced the need for validation and specified the three techniques most requiring validation. The second paper detailed the results of an extensive independent validation experiment. This experimental validation involved 30 UK assessors using the techniques THERP, HEART and JHEDI (10 assessors per technique) to estimate the human error probabilities (HEPs) for 30 nuclear power and reprocessing (NP&R) tasks. The results for all three techniques were positive in terms of significant correlations, and general precision levels of 72% of all HEP estimates within a factor of 10 of the true value (unknown to the assessors). These results lend support to the empirical validity of these techniques in particular, and to HRA in general. However, the results were not all positive. In particular the consistency of usage of the techniques was variable. Additionally, subjects were generally not good at knowing their own uncertainty, i.e. they were not able to accurately predict when they were accurate nor when they were inaccurate. This desirable parameter is known as calibration, and the results from the validation suggested that subjects were not well-calibrated. This paper aims to determine how consistency of usage can be improved and to discern whether certain task types are, in practice, not well-assessed by the techniques, and hence are effectively currently beyond these techniques' abilities. Such information is aimed at aiding the HRA practitioner, or the ergonomist, interested in using these techniques. Recommendations for improving calibration are also discussed in this paper. A subsidiary but important focus of this paper is of a more fundamental nature, and of more general interest to the ergonomist. It concerns the validity of the techniques from an error reduction perspective. Currently these techniques may be used to identify how to reduce error probability, which is generally (in the qualitative sense) within the domain of ergonomics. One major mechanism for HRA-based error reduction is the utilisation of Performance Shaping Factor (PSF) information. This paper considers the validity of these PSF as ergonomics constructs. Drawing results from the validation exercise, it is seen how different PSF can be applied to the same scenario and can result in the same error probability, but will result in different error reduction guidance. It is therefore recommended that error reduction guidance must be based on a composite analysis of the results of the task, error identification and quantification analyses, with most weighting given to the qualitative analyses.

Evaluation Studies as Topic↗