Reliability prediction in healthcare systems or subsystems by identifying single points of failure

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1 Hosp Aeronáut Cent 2013; 8(2): Reliability prediction in healthcare systems or subsystems by identifying single points of failure My. (E. Med.) Rubén D. Algieri*, Carlos Lazzarino**, 1er Ten. e.c. (E. Med.) Alejandro Ciano***, 1er Ten. e.c. (E. Med.) Silvina Marco***, 1er Ten. (E. Med.) Felix Viglione***, 1er Ten. (E. Med.) Fabiana Alanis*** Workplace: General Surgery Department. Hospital Aeronáutico Central Ventura de la Vega St., City of Buenos Aires. * Head of General Surgery Department. Hospital Aeronáutico Central. ** Surgeon on-duty. Hospital Municipal de Morón. *** General Surgery Resident. Hospital Aeronáutico Central. Resumen Abstract Introducción: Los puntos únicos de falla hacen referencia a cualquier elemento o componente de un sistema o subsistema que, al fallar en su funcionamiento, ocasione un fallo global en todo el sistema. Objetivos: Demarcar el valor de la fiabilidad en los sistemas o subsistemas sanitarios. Material y método: Se analizó la disponibilidad total quirúrgica entre enero de 2011 y enero de 2012, a partir de los procedimientos suspendidos por causas no inherentes a la morbilidad del enfermo, en los módulos quirúrgicos / anestésicos programados para Servicio de Cirugía General en el Hospital Aeronáutico Central. Resultados: De 475 cirugías programadas entre enero de 2011 y enero de 2012, se suspendieron 25 procedimientos (5,2%). Cálculo de la Disponibilidad: 94,76%. El impacto de la inactividad resultó en la reprogramación de 25 cirugías. Conclusiones: La Gestión de la Disponibilidad permite mejorar la fiabilidad y, de esta forma, lograr una mejor gestión sanatorial y hospitalaria, reducir los riesgos evitables más comunes que puedan poner en peligro el bienestar y la vida del paciente. Palabras clave: Puntos de falla únicos, fiabilidad de sistemas sanitarios. Received: August 1 st, Accepted: August 30th, Introduction: Single points of failure refer to any element or part of a system or subsystem that if fails produces the global failure of the whole system. Objectives: To demarcate the value of reliability in healthcare systems or subsystems. Material and Method: Surgical total availability between January 2011 and January 2012 was analyzed, considering the procedures suspended due to causes not related to the patient s morbidity, in the surgical/anesthetic modules scheduled for the General Surgery Department of the Hospital Aeronáutico Central. Results: 25 procedures (5.2%), out of 475 scheduled surgeries, were suspended between January 2011 and January Availability calculation: 94.76%. The impact of inactivity led to 25 re-scheduled surgeries. Conclusions: Availability management makes it possible to improve reliability and, thus, achieve better clinic and hospital management, and reduce the most common avoidable risks that could endanger the patient s life and well-being. Keywords: Single points of failure. Reliability of healthcare systems. 98

2 Algieri et al, Hosp Aeronáut Cent 2013; 8(2): Introduction A system is defined as a set of appropriately interrelated components arranged according to a certain design with the purpose of fulfilling certain functions with acceptable reliability. Furthermore, systems may be constituted by subsystems. Reliability refers to the probability that a system or subsystem works appropriately during a period under specific operative conditions. The way the components interrelate with each other, as well as their quality and quantity, have direct consequences on the system reliability, and that is directly related to availability. One of the criterions used to analyze availability is the existence of single points of failure. These points refer to any item or component of a system or subsystem that, if fails, may lead to a global failure of the whole system. Actions aimed at Availability Management through the appropriate arbitration of the system components allow for the improvement of its reliability and, in this way, the achievement of a better clinic and hospital management which, undoubtedly, has consequences on health care quality. Objectives procedures suspended due to causes not related to patient s morbidity, in the surgical / anesthetic modules scheduled for the General Surgery Department of the Hospital Aeronáutico Central. Results 25 procedures (5.2%), out of 475 scheduled surgeries, were suspended between January 2011 and January Table 1: Scheduled Surgeries suspended between January 2011 and January January 3 July 1 February 2 August 2 March 3 September 1 April 2 October 3 May 1 November 2 Jan Feb March April May June July Aug Sep Oct Nov Dec June 1 December 4 Graph 1: To demarcate the value of reliability in healthcare systems or subsystems. Material and Methods Surgical total availability between January 2011 and January 2012 was analyzed, considering the Table 2: Rate of suspended surgical procedures: N % Bed Shortage at Closed Unit Blood Shortage Technical Equipment Operating Room Other Hospital Aeronáutico Central Journal 99

3 Reliability prediction in healthcare systems or subsystems by identifying single points of failure carry out maintenance tasks without interrupting the system operation. Calculation of basic Availability Availability = ((TST DT) / TST) * 100 Where, TST = Total Service Time possible during the period for which the calculation has been made DT = real Down Time recorded during the period for which the calculation has been made Although they are usually indistinctly used, it is worth mentioning that uptime and availability are not synonyms. Table 1: High Availability Challenges 4 (Adapted from Introduction to Availability Management ITIL) Availability Calculation: 94.76%. The impact of inactivity led to 25 re-scheduled surgeries. Discussion The availability of a system is related to the capability it has to be used in relation to a certain time. Systems which have null down-time in case of failure are called High Availability systems. Availability may be expressed as a percentage of the uptime in a certain time 2,3,6. Downtime may be planned or unplanned. Usually, unplanned downtime is the consequence of the occurrence of an adverse event, whether it is intrinsic to the system or substantially external to it. Generally, planned downtime constitutes a management or scheduled maintenance event. In one way or another, this time always has an impact on the community which has influence over the system. Therefore, it would be ideal to Fault-tolerant infrastructure Eliminate single points of failure Failure protection Quick system recovery Human error protection Eliminate / minimize planned downtime periods High availability at a low cost Some subsystems may be operating and not available at the same time. There is no doubt that it is ideal for a system to be operating 100% of time. However, certain factors determine that availability measurement be subjective. Partial performance problems can be estimated as non available according to perception and, also, a system that has been operating 99.9% of time can be eclipsed by a failure which may last some hours in a peak use period. 100

4 Algieri et al, Hosp Aeronáut Cent 2013; 8(2): Table 1: Factors affecting availability perception 1. Duration of the Incidents which result in No availability 2. Frequency of occurrence of said incidents 3. Duration and frequency of planned maintenance. 4. Impact scale and scope These availability values are related to other concepts. One of them is the recovery time, which refers to the total time required to complete the activity from a planned inactivity period. Every system requires maintenance to ensure its continuous use. Two types of maintenance are defined: preventive and corrective. Preventive maintenance entails expenses to avoid failures in the service, while corrective maintenance (repair) is the answer to a failure which has already occurred for the system to be restored to its normal operational state. These concepts are widely used in aeronautics and in financial institutions. In practice, reliability can be measured as the mean time between maintenance cycles or the mean time between two consecutive failures (Mean Time Between Failures). In series systems, the whole system will be as reliable as its link most prone to failures. In this way, to ensure the absence of single points of failure in the system, computing or electrical systems incorporate redundancy into all their components in order to keep the system working properly even if some of its components fail. Systems and subsystems designed that way are called fault-tolerant 7. Single points of failure should be avoided in any system or subsystem where high availability is desired, since a failure may directly endanger the global operation of the system. Replicating the components can be a solution, but paradoxically, adding more components can also increase the total complexity of the system since they can have more potential points of failure. This entails deepening the analysis to the whole system and not only to each component. Components redundancy can be active (all redundant components are active and working) or sequential (also called passive, the redundant element only activates when the primary element fails). Similarly to health systems, in some high availability systems there are elements which redundancy is extremely expensive and adversely affects the cost-benefit relation. It is at that moment when availability management tries to justify the expenses of improvements in order to obtain a system with more efficient subsystems. Typical examples of that are the eventual electromechanical failure of the operating room technical equipment (as may be fluoroscopy and laparoscopy equipment, radiolucent or anesthesia tables), the depletion of the relevant blood group within the hospital blood bank and the lack of bed in the closed unit in case it is required for the postoperative period. Own, intrinsic and nonpredictable causes of the patient s morbid process should always be excluded. Depending on the results, the applicable measures to improve availability should be sought. The identification of alternative components to the single point of failure is the part of Management that aims specifically at reducing failures 1,5. In this way, an action plan can be developed following a priority order so as to improve availability through infrastructure modification. Hospital Aeronáutico Central Journal 101

5 Reliability prediction in healthcare systems or subsystems by identifying single points of failure Conclusions Literature This new paradigm, driven by the culture of health care safety established by the WHO, gives rise to a series of new concepts which may be implemented from the moment the infrastructures are designed in almost all medical systems and subsystems. High availability systems are the objective of public health medicine in general and, specifically, in urgency and emergency. Availability Management makes it possible to improve reliability and, thus, achieve better clinic and hospital management. This aims at reducing the most common avoidable risks that could endanger the patient s life and well-being, since adverse events lead to the increase of morbidity and mortality, hospital stay extension and, of course, the increment of health care costs at the expense of the medical service quality. 1. Brennan, Leape, Laird. Incidence of adverse events and negligence in hospitalized patients. N Engl J Med 1991; 324: Carlos Prieto García: Fiabilidad, Mantenibilidad y Mantenimiento; Universidad de Sevilla, Área de Ingeniería Mecánica, Sevilla 3. Fermín Mallor, Javier Santos: Fiabilidad de Sistemas; Universidad pública de Navarra, Área de Ingeniería Mecánica, Navarra 4. George R, Introducción a la Gestión de Disponibilidad ITIL en: Recursos ITIL / Gestión de Servicios TI (ITSM), Libros Blancos, España. 5. Iribarren C, Arribalzaga EB, Curutchet HP. Error Médico en Cirugía. Rev Argent Cirug, 2003; 85 (3-4): Juan Valencia Atango, Estimación del tiempo medio de falla cuando sólo es posible observar un punto en el tiempo,, Universidad Nacional de Colombia 7. Linux-HA Web Site: 102