Risk-effectiveness analysis

Methods for performing hazard analysis and risk assessment include safety review, checkhsts, Dow Fire and Explosion Index, what-if analysis, hazard and operabihty analysis (HAZOP), failure modes and effects analysis (FMEA), fault tree analysis, and event tree analysis. Other methods are also available, but those given are used most often. 

A risk assessment analyses systems at two levels. The first level defines the functions the system must perform to respond successfully to an accident. The second level identifies the hardware for the systems use. The hardware identification (in the top event statement) describes minimum system operability and system boundaries (interfaces). Experience shows that the interfaces between a frontline system and its support systems are important to the system cs aluaiion and require a formal search to document the interactions. Such is facilitated by a failure modes and effect analysis (FMEA). Table S.4.4-2 is an example of an interaction FMEA for the interlace and support requirements for system operation. 

A failure modes and effects analysis is a systematic analytical technique for identifying potential failures in a design or a process, assessing the probability of occurrence and likely effect, and determining the measures needed to eliminate, contain, or control the effects. Action taken on the basis of an FMEA will improve safety, performance, reliability, maintainability and reduce costs. The outputs are essential to balanced and effective quality plans for both development and production as it will help focus the controls upon those products, processes, and characteristics that are at risk. It is not the intention here to give a full appreciation of the FMEA technique and readers are advised to consult other texts. 

An effective HE or cost-effectiveness analysis is designed to answer certain questions, such as Is the treatment effective What will it cost and How do the gains compare with the costs By combining answers to all of these questions, the technique helps decision makers weigh the factors, compare alternative treatments, and decide which treatments are most appropriate for specific situations. Typically, one chooses the option with the least cost per unit of measure gained the results are represented by the ratio of cost to effectiveness (C E). With this type of analysis, called a cost-effectiveness analysis (CEA), various disease end points that are affected by therapy (risk markers, disease severity, death) can be assessed by corresponding indexes of therapeutic outcome (mmHg blood pressure reduction, hospitalizations averted, life years saved, respectively). It is beyond the scope of this chapter to elaborate further on principles of cost-effectiveness analyses. A number of references are available for this purpose [11-13]. 

Professor Martel s book addresses specifically some of the more technical eispects of the risk assessment process, mainly in the areas of hazard identification, and of the consequence/effect analysis elements, of the overall analysis whilst where appropriate setting these aspects in the wider context. The book brings together a substantial corpus of information, drawn from a number of sources, about the toxic, flammable and explosive properties and effect (ie harm) characteristics of a wide range of chemical substances likely to be found in industry eind in the laboratory, and also addresses a spectrum of dangerous reactions of, or between, such substances which may be encountered. This approach follows the classical methodology and procedures of hazard identification, analysing material properties eind... 

Sometimes it is easiest to prepare a general flowchart that identifies events which may occur at a facility during an incident. This flowchart can identify possible avenues the event may lead to and the protection measures available to mitigate and protect the facility. It will also highlight deficiencies. The use of a flowchart helps the understanding of events by personal unfamiliar with petroleum risk and safety measures. It portrays a step by step scenarios that is easy to follow or explain. Preparation of in-depth risk probability analysis can also use the flowchart as the basis of the event trees or failure modes and effects. Figure 3 provides a generic example of a typical hydrocarbon process facility Safety Flowchart. API Recommended Practice RP 14C provides an example of a Safety Flowchart for an offshore production facility. 

Several catastrophic fire incidents in the petroleum industry have been the result of the facility firewater pumps being directly affected by the initial effects of the incident. The cause of these impacts has been mainly due to the siting of the fire pumps in vulnerable locations without adequate protection measures from the probable incident and the unavailability or provision of other backup water sources. A single point failure analysis of firewater distribution systems is an effective analysis that can be performed to identify where design deficiencies may exist. For all high risk locations, fire water supplies should be available from several remotely located sources that are totally independent of each and utility systems which are required for support. 

Several qualitative approaches can be used to identify hazardous reaction scenarios, including process hazard analysis, checklists, chemical interaction matrices, and an experience-based review. CCPS (1995a p. 176) describes nine hazard evaluation procedures that can be used to identify hazardous reaction scenarios-checklists, Dow fire and explosion indices, preliminary hazard analysis, what-if analysis, failure modes and effects analysis (FMEA), HAZOP study, fault tree analysis, human error analysis, and quantitative risk analysis. 

The PHA procedure can be conducted using various methodologies. For example, the checklist analysis discussed earlier is an effective methodology. In addition, Pareto analysis, relative ranking, pre-removal risk assessment (PRRA), change analysis, failure mode and effects analysis (FMEA), fault tree analysis, event tree analysis, event and CF charting, PrHA, what-if analysis, and HAZOP can be used in conducting the PHA. 

Risk assessment tools such as a nine-block risk assessment (Table 9) or a failure mode and effect analysis (FMEA) are available to assist the process owner with the evaluation of the process or issue to better understand and communicate the... 

DeRosier J, Stalhandske E, Bagian JP, et al. 2002. Using health care failure mode and effect analysis The VANa-tional Center for Patient Safety s prospective risk analysis system. Joint Comm J Qual Improv 28 248. 

Describe what changes are needed at the risk management level to better address medication safety issues, including the use of failure mode and effects analysis to reduce the... 

The process hazards analysis is conducted by an experienced, multidisciplinary team that examines the process design, plant equipment, operating procedures, and so on, using techniques such as hazard and operability studies (HAZOP), failure mode and effect analysis (FMEA), and others. The process hazards analysis recommends appropriate measures to reduce the risk, including (but not limited to) the safety interlocks to be implemented in the safety interlock system. 

Reinert KH, Giddings JM, Judd L. 2002. Effects analysis of time-varying or repeated exposures in aquatic ecological risk assessment of agrochemicals. Environ Toxicol Chem 21 1977-1992. 

The total risk approach accounts for the total dissolved metal in a water body, implying that no distinction is made between the ambient fraction of a metal in a water body and the added fraction (Lepper 2005). This approach can result in a standard below the natural background. Hence, a suggestion in the European Union to account for background is the added risk approach. It allows interpretation of the outcome of exposure and effects analysis or risk characterization in terms of the different fractions (i.e., the natural background [total metal]) and the anthropogenic fraction. 

With every drug use, unwanted effects must be taken into account. Before prescribing a drug, the physician should therefore do a risk-benefit analysis. 

The main, though certainly not the only, challenge of ECT is its effect on memory. Typically, ECT-treated patients will experience various degrees of amnesia. In most, full memory is restored within several weeks after treatment. However, a small minority of patients will continue to have memory problems for months or even years. Two important techniques have reduced, but not eliminated, this problem. One is the use of devices that deliver electrical waves in a form and intensity less likely to induce amnestic complications. The other is electrode placement. Traditionally, the electrodes are positioned bilaterally, one on each side of the skull. Research has shown that placing both electrodes on one side of the brain—usually the nondominant hemisphere, which for most people is the right hemisphere—can substantially reduce the incidence of amnesia. In a number of cases, however, some loss of efficacy may result when unilateral placement is used. Thus the physician and the patient need to make the appropriate risk-benefit analysis in selecting a technique. 

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