Dexter F, Coffin S, Woodward J
Department of Anesthesia, University of Iowa, Iowa City 52242, USA.
J Clin Monit. 1997 May;13(3):171-9. doi: 10.1023/a:1007302030065.
The Food and Drug Administration's (FDA) checkout recommendations are to be applied, at least daily, on anesthesia machines. Devices included in the checkout are crucial to the safe operation of the machine. Remaining devices do not need to be checked as often. However, they should be checked at some appropriate interval. We calculated the reliability of the non-FDA checkout devices, to predict failure rates of these devices.
The study included 36 North American Drager Narkomed anesthesia machines that were in service a total of 109,410 days at a university hospital. Reliability (i.e., statistical) analyses were done using in-house data recorded by biomedical technicians during 3359 monthly machine inspections. If any one device was operating outside of the limits of the manufacturer's specifications, the machine was labeled as having failed its inspection.
Assumptions of the failure analysis were satisfied. The mean time between failures equaled 1351 days or 3.7 years (lower 95% confidence bound 1123 days or 3.1 years). The mean daily probability of one or more devices failing to perform within the manufacturer's specification between inspections equaled 1.1, 2.2%, and 4.4% for inspections every 1, 2, or 4 months, respectively. Probabilities that a machine would fail on demand between inspections were approximately equal to the mean daily probabilities of machine failure. The mean number of days per year that a machine would be operating with a device that is outside of the limits of its specifications equaled 4, 8, and 12, days, respectively. The mean daily probabilities of failure and the probabilities of failure on demand were both directly proportional to the inspection interval.
Our failure analysis provides a rational basis for choosing an appropriate inspection interval for anesthesia machines' devices that are not included in the FDA's checkout recommendations.
美国食品药品监督管理局（FDA）的检查建议应至少每天应用于麻醉机。检查中包括的设备对机器的安全运行至关重要。其余设备无需如此频繁地检查。然而，应在适当的间隔进行检查。我们计算了非FDA检查设备的可靠性，以预测这些设备的故障率。
该研究纳入了36台北美Drager Narkomed麻醉机，这些麻醉机在一所大学医院共使用了109,410天。使用生物医学技术人员在3359次每月机器检查期间记录的内部数据进行可靠性（即统计）分析。如果任何一个设备的运行超出了制造商规格的范围，该机器即被标记为检查不合格。
故障分析的假设得到满足。平均故障间隔时间为1351天或3.7年（95%置信下限为1123天或3.1年）。对于每1、2或4个月进行一次检查，在两次检查之间一个或多个设备未能在制造商规格范围内运行的平均每日概率分别为1.1%、2.2%和4.4%。机器在两次检查之间按需出现故障的概率大约等于机器故障的平均每日概率。每年一台机器使用超出其规格范围的设备运行的平均天数分别为4天、8天和12天。故障的平均每日概率和按需出现故障的概率均与检查间隔成正比。
我们的故障分析为选择FDA检查建议未涵盖的麻醉机设备的适当检查间隔提供了合理依据。
