Dissertation
Dissertation > Medicine, health > Basic Medical > Medical science in general > Biomedical Engineering > Apparatus, equipment

The Study of Ethylene Oxide Sterilization Indicators Comprehensive Evaluator Resistometer and Influence of Parameters for Ethylene Oxide Sterilization

Author WangJiaQi
Tutor ZhangLiuBo
School Disease Control and Prevention Center
Course Public Health
Keywords ethylene oxide resistometer sterilization monitoring Dvalue
CLC R318.6
Type Master's thesis
Year 2013
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Objectives1. Ethylene Oxide Sterilization Indicators Comprehensive Evaluator Resistometer will be developed for the research of ethylene oxide sterilization and the quality inspection of sterilization indicator and other related products.2. The present monitoring situation of ethylene oxide sterilization in hospitals will be learnt about, and the present quality state of biological monitoring products will be got through the quality evaluation of a few biological monitoring products used in the hospitals.3. In the laboratory conditions, the effects of temperature, relative humidity and the concentration of ethylene oxide on the ethylene oxide sterilization will be explored to seek suitable parameters for the sterilization.Method1. According to parameters requirements of epoxy ethane resistance tester in GB/T24628-2009, and requirements of the test cycle in GB18281.1-2000and GB18282.1-2000, the key parameters such as temperature, relative humidity, pressure, concentration of epoxy ethane and exposure time were precisely controlled to produce accurate controlled test cycle. A self-contained biological indicator was chosen for the resistance test and the results were compared with that of ethylene oxide resistance meter of the same kind.2. Questionnaires on the usage of the ethylene oxide sterilizing cabinet and knowledges of sterilization monitoring for operators were designed. It included:the basic situation, daily use situation and biological and chemical monitoring of the use of ethylene oxide sterilization instruments, and so on. Questionnaires were sent to9hospitals in different cities and provinces, to conduct a survey on the situation for a quarter (from January1st,2012to March3lth,2012).3. According to the requirements in GB18281.1-2000, D value was got in survival curve method, and the effects of temperatures, relative humidity and the concentration of ethylene oxide on sterilization were researched.Results 1. D value and the error of the products nominal value for the self-contained biological indicator tested by Ethylene Oxide Sterilization Indicators Comprehensive Evaluator Resistometer, conformed to the standard requirements. It had almost the same resistance test results as epoxy ethane resistance detector of the same kind.2. The survey results of ethylene oxide sterilization cabinets used in9hospitals were found that, operations of ethylene oxide sterilization in all hospitals were standard, and both chemical monitoring and biological monitoring in the183sterilization monitoring for3months had one unqualified case. Both the domestic and imported epoxy ethane biological indicators selected met the standard requirements of performance3. The influences of temperature, concentration and relative humidity on the process of ethylene oxide sterilization were as follows:1) The effect of temperature on sterilization was the greatest. In the range of30℃~70℃, D values decreased rapidly with the temperature increasing. It can be seen from the curve of temperature-D value, beyond50℃, temperature raising had little effect on the D value.2) In the range of400mg/L~1000mg/L, with the increase of ethylene oxide concentration, D values decreased gradually, from4.7minutes to2.2minutes. The concentration doubled, D values decreased about1/2, when up to600mg/L, the concentration-D value curve declined slower. 3) When the relative humidity changed in the range of30%~80%, the sterilization effect was the best at30%, with the increase of relative humidity, D value increased gradually, from2.3minutes to3.3minutes.Conclusion1. Ethylene oxide sterilization indicator resistance integrated detector is accurate, and can reproduce the test sterilization environments. The mechanical design, performance of sensors, the related parameters and test cycle all meet the national standard requirements, and it can be used for the performance evaluation of biological indicator and chemical indicator for ethylene oxide sterilization.2. In the actual operation of ethylene oxide sterilization, it is suggested to reduce the frequency of biological and chemical monitoring, at the same time, increase the monitoring of EO concentration in the environment, and strengthen personal protective measures.3.In the laboratory conditions, the effects of ethylene oxide sterilization are better when the temperature is50℃, the concentration of ethylene oxide is600mg/L, and relative humidity is30%. It still needs further validation in the practical application.

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