Using Healthcare Failure Mode and Effect Analysis Tool to Review the Process of Ordering and Administrating Potassium Chloride and Potassium Phosphate
During the spring of 2004, in the Calgary Health Region (CHR) two critical incidents occurred involving patients receiving continuous renal replacement therapy (CRRT) in the intensive care unit (ICU). The outcome of these events resulted in the sudden death of both patients.
The Department of Critical Care Medicine's Patient Safety and Adverse Events Team (PSAT), utilized the Healthcare Failure Mode and Effect Analysis (HFMEA) tool to review the process and conditions surrounding the ordering and administration of potassium chloride (KCl) and potassium phosphate (KPO4) in our ICUs.
The HFMEA tool and the multidisciplinary team structure provided a solid framework for systematic analysis and prioritization of areas for improvement regarding the use of intravenous, high-concentration KCL and KPO4 in the ICU.
For the Calgary Health Region (CHR), patient safety was brought to the forefront in the spring of 2004, when there were two critical incidents that resulted in the death of two patients receiving CRRT in two different ICUs of the CHR (ISMP alert March 25, 2004). Here is a brief description of the incidents from the External Patient Safety Review (June 2004):
" An 83-year-old woman who was a patient in the cardio-vascular care unit at the Foothills Medical Center (FMC) site of the CHR died suddenly in the presence of her physician and members of her family. She was alert and oriented at the time and her condition, while very serious, did not seem to indicate reasons for immediate concern. Her unexpected death was devastating for her family and extremely distressing for all those involved in her care. An ICU physician suspected the cause - the composition of dialysate solution being used to treat her kidney failure. This was quickly confirmed and 30 bags of the solution made in the same batch were removed from patient care areas, undoubtedly preventing the deaths of other patients. An analysis of the other bags from that batch as well as a systematic review of patient records identified a second patient whose death, one week earlier, was likely caused by the same set of circumstances. This was not suspected at the time of death due to the patient's serious condition."
Upon further investigation, it was determined that in February 2004, pharmacy technicians in the central production facility of the CHR pharmacy department prepared a dialysate solution for patients receiving CRRT. During the process, KCL was inadvertently added to the dialysate bags instead of sodium chloride (NaCl) solution. It is believed that these incorrectly prepared solutions were used in the dialysis of the two patients who died (External Patient Safety Review, CHR June 2004).
The CHR publicly disclosed the facts and initiated an external patient safety review. The Department of Critical Care Medicine (DCCM) also undertook a review of the process for ordering and administering intravenous, high-concentration KCl and KPO4, using the HFMEA tool developed by DeRosier, Joseph et al. (2002). The focus of this article is to describe the application of the tool with respect to reviewing the processes involved in ordering and administering intravenous, high-concentration KCl and KPO4, thereby allowing the DCCM to proactively identify hazards that may exist and establish a safer process.
The DCCM has been engaged in ongoing quality improvement and patient safety initiatives both formally and informally for over 10 years (Esmail et al. 2005). At present, the region includes three adult acute care teaching hospitals and one pediatric hospital: Foothills Medical Centre (FMC), Peter Lougheed Center (PLC), Rockyview General Hospital (RGH) and the Alberta Children's Hospital. The Department of Critical Care Medicine oversees four adult intensive care units:
- A 24-bed Multisystem ICU (FMC)
- A 14-bed Cardiovascular ICU (FMC)
- A 12-bed Multisystem ICUs (PLC)
- A 10-bed Multisystem ICUs (RGH)
HFMEA vs Failure Mode and Effect Analysis (FMEA)
In the past, medicine used a human error approach which identified the individual as the cause of the adverse event. We now recognize that errors are caused by system or process failures (McNally et al. 1997). FMEA was developed for use by the United States military and is utilized by the National Aeronautics and Space Administration (NASA), to predict and evaluate potential failures and unrecognized hazards and to proactively identify steps in a process that could help reduce or eliminate a failure from occurring (Reiling et al. 2003). FMEA focuses on the system within an environment and uses a multidisciplinary team to evaluate a process from a quality improvement perspective. The Joint Commission for Accreditation of Healthcare Organizations (JCAHO) in the US has recommended that healthcare institutions conduct proactive risk management activities that identify and predict system weaknesses and adopt changes to minimize patient harm (Adachi et al. 2001).
In 2001 the Veteran's Administration (VA) National Centre for Patient Safety (NCPS) specifically designed the HFMEA tool for risk assessment in the healthcare field.
The HFMEA tool was formed by combining industry's FMEA model with the U.S. Food and Drug Administration's Hazard Analysis and Critical Control Point (HACCP) tool together with components from the VA's root cause analysis (RCA) process. HACCP was developed to protect food from chemical and biological contamination and physical hazards. The HACCP system uses seven steps: (1) conduct a hazard analysis, (2) identify critical control points, (3) establish critical limits, (4) establish monitoring procedures, (5) establish corrective actions, (6) establish verification procedures, and (7) establish record-keeping and documentation procedures (Center for Food Safety and Applied Nutrition, 1997). It uses questions to probe for food system vulnerabilities as well as a decision tree to identify critical control points. The decision tree concept was adapted by the VA for the HFMEA tool. The HFMEA tool has been subsequently recognized in the White Paper prepared by the American Society for Healthcare Risk Management (ASHRM). In an effort to globally share the merits of this process, a video, instructional CD and worksheets on the use and application of HFMEA has been sent to every hospital CEO in the US to be shared with individuals and risk managers responsible for patient safety (American Society for Health Risk Management 2002).
There are five steps in the HFMEA tool. Step one is to define the topic; step two is to assemble the team; step three requires the development of a process map for the topic and consecutively numbering each step and substeps of that process; step four is to conduct the hazard analysis. This step involves four processes: the identification of failure modes, identification of the causes of these failure modes, scoring each failure mode using the Hazard Scoring Matrix, and working through the Decision Tree Analysis. The final step is to develop actions and outcomes. The next section will describe how the DCCM's Patient Safety and Adverse Events team (PSAT) worked through each step of the HFMEA tool to review the process of ordering process of ordering intravenous, high-concentration KCl and KPO4.
HFMEA - Step One
Step one is to define the HFMEA topic. The topic is usually a process that has high vulnerabilities and potential for impacting patient safety. It is important in a HFMEA analysis to define boundaries and limit the scope of the topic being reviewed.
Following the two previously mentioned critical incidents, two reviews were conducted in the CHR. The first was an internal review and was conducted by the Patient Safety Task Force, and the second was considered external and performed by the External Patient Safety Review Committee (June 2004). During the same time, in response to the tragic events from March 2004, disparate and poorly coordinated changes in policy regarding the storage and use of highly concentrated potassium were initiated within the regional ICUs. The department's ICU executive council determined the need to undertake a review of the process for the general handling of intravenous, high-concentration KCl and KPO4 prior to reviewing the process of preparing CRRT bags for dialysis. It was understood that some of the steps in this process would overlap with the CRRT process.
HFMEA - Step Two
Step two in the HFMEA tool is to assemble a team. The team should include six to eight multidisciplinary members who are involved in the process being analyzed and are to some degree considered "subject matter" experts.
The department's PSAT was assigned this task. The team was co-led by an intensivist and the department's quality improvement and patient safety consultant. The team was multidisciplinary, with two intensivists, three respiratory therapists, two nursing educators, two frontline nursing staff from each hospital site and two pharmacists. The team had been previously working on chart reviews of adverse events using the IHI trigger tool methodology (Rozich et al. 2003) and staff education with respect to incidents and incident reporting. The team met every other week over a two-month period (April and May 2004).
HFMEA - Step Three
Step three of the HFMEA tool requires the development of a process map for the topic and consecutively numbering each step and substeps of that process. If the process is too complex, a specific area within the overall process can be focused upon. The team identified 11 steps in the process of ordering and administering KCl and KPO4 (Figure 1). After reviewing these 11 steps, the team focused on two critical steps: obtaining the drug (step #6) and mixing the drug (step #7) and then identified the substeps for each of these two HFMEA steps (Figure 2). Site visits to review where KCL and KPO4 were stored and conversations with frontline staff in the units to verify the process were also conducted.
HFMEA -Step Four
In step four of the HFMEA tool, the area of focus is further narrowed using the following four processes: identification of failure modes, identification of the causes of these failure modes, scoring each failure mode using the Hazard Scoring Matrix, and working through the Decision Tree Analysis (DeRosier et al. 2002). The team identified the failure modes for steps #6 and #7 (Figure 2). The failure modes that received the highest hazards scores were: nurse selecting the wrong drug, distractions when mixing and inaccurate, or incomplete labels. Using the HFMEA decision tree analysis, the team worked through each hazard to determine if it needed further action.
HFMEA - Step Five
In step five of the HFMEA tool, actions are developed. Actions to address the identified hazards need to focus on root causes or contributing factors and need to be specific and concrete. Frontline staff involved directly in the process need to review them. Actions can then be tested prior to implementation using the Improvement Model methodology that includes testing changes using the Plan-Do-Study-Act (PDSA) cycle (Langley et al. 1996). Outcomes must be measurable, with a defined sampling strategy, set timeframe for measurement and with a realistic well-articulated goal.
Eleven recommendations were developed based on this analysis (Appendix I). These recommendations were placed into two categories, general and ICU-specific, and subsequently presented to the ICU executive council in July 2004. These recommendations addressed how KCl and KPO4 are to be stored and who, where, and how the drugs are to be mixed. These recommendations also focused on the identification of look-alike and sound-alike products based on human factor principles (Gosbee et al. 2002 and Wickens et al. 2004). Key recommendations were summarized into an action plan with delegated responsibility and timelines for implementation (Figure 3).
Implementation of the recommendations has proven to be more difficult than the HFMEA process itself. Once the recommendations were presented and approved at ICU executive council, those that were key ICU-specific recommendations were primarily delegated to pharmacy, unit patient care managers (PCMs) and unit directors and PSAT for implementation with specified timelines. For example, for recommendation #2, a "safety snippet" on the seven rights of drug administration was developed by a PSAT member and posted on the internal DCCM website to educate staff. Recommendations that had a broader regional impact were shared with the region's working group on high-risk medications who were developing a regional policy on KCl. The region is also in the process of developing standard labels for look-alike and sound-alike drugs.
Team Lessons Learned
HFMEA was well recognized by the PSAT and it provided a solid framework for the step-by-step analysis of potassium ordering and administration. The team members were unaware of the numerous steps involved in administrating this medication and it became obvious that there were many opportunities for errors to occur. HFMEA enabled the team to prioritize the critical items of a complex process and took the subjectivity out of the analysis.
The multidisciplinary structure of PSAT allowed members to identify each step from their own professional practice perspective. The PSAT composition also generated diverse ideas when brainstorming actions and allowed for good discussion and deliberation, which ultimately promoted team building.
HFMEA was an easy tool to use by all members of the team. It made the approach to a very complicated process relatively straightforward. Using the HFMEA tool, the two leaders were able to focus the team on the specific components of the tool. The tool enabled the team to develop a structured outline of the goals that needed to be accomplished at each meeting. The team has also used this tool to analyze the hazards of the process for preparing CRRT bags for dialysis patients in the ICU.
Although the work of the PSAT was extremely valuable for the department, it was also time consuming. It would be appropriate to conduct a HFMEA analysis on one or two high-priority topics per year as has been recommended by the Joint Commission on Accreditation of Health Care Organizations in the United States (Adachi et al. 2001).
Pharmacy Lessons Learned
The dialysate manufacturing error came as a harsh reminder to the CHR's pharmacy department of its need for structured policies and procedures for error avoidance. This error occurred despite existing safety procedures that including four double checks by pharmacists. The risks associated with intravenous potassium came to the forefront of the pharmacy department's focus and there was a heightened awareness of pharmacy's role in patient safety.
Since 2002, intravenous high concentration KCL vials have not been available in most patient care areas in the CHR. Premixed KCL bags are available and any special bags not commercially available are to be mixed in the pharmacy department. These policies are based on the ISMP Canada recommendations (2002) and also reiterated in the PSAT recommendations. Prior to the incidents, intravenous potassium vials were available in the night dispensary for use while the pharmacy was closed; these have now been replaced by premixed bags. The only vials of intravenous potassium available outside the pharmacy department include a small supply of KCl vials kept in narcotic cupboards of critical care and dialysis units. These vials are to be used for special CRRT solutions only.
Before the dialysate manufacturing error occurred, intra-venous potassium vials were stored on the regular drug shelves within the pharmacy department. Since the error, all intra-venous potassium vials are stored in a separate, locked area within the pharmacy. All intravenous potassium vials and minibags are now labelled with a warning sticker to further distinguish them, as per the recommendation from ISMP Canada (ISMP alert 2002).
Additionally, drug identification numbers have been added to the manufacturing worksheets used by pharmacy technicians in the sterile product preparation area. This adds redundancy through checking of the procedure for sterile products, including dialysate. Batches of dialysate are now quarantined until potassium levels in each batch are confirmed to be zero by laboratory testing.
By changing preparation, manufacturing, labelling and storage procedures for intravenous potassium products, the risk of error has been substantially reduced.
This article described the use of the HFMEA tool developed by the VA and its application in the process of ordering and administrating intravenous high-concentration KCL and KPO4. Eleven recommendations resulted from this analysis. The ICU-specific recommendations that did not incur costs were implemented expeditiously. General recommendations, which were not under the purview of the DCCM, were shared with CHR's Regional Patient Safety Committee, which has since developed a regional policy on KCl.
In addition to this work, the knowledge and understanding gained from the application of the HFMEA tool by DCCM's PSAT will be shared with the Regional Patient Safety Transport working group reviewing patient transport between hospitals. This group has been formed based on recommendations from the External Patient Safety Review (June 2004). The Quality, Safety & Health Information Portfolio of the region is also in the process of determining the use or modification of this tool to proactively identify hazards in the system.
More importantly, the two critical incidents served as triggers that brought patient safety to the forefront for the CHR and the DCCM. Numerous changes and initiatives based on the recommendations from the internal and external reviews have been initiated or are underway with an attempt to transform the culture of the organization to one with a much greater awareness of hazard identification, incident and near miss reporting and patient safety.
Appendix 1: Recommendations
1. Use premixed solutions for high-risk drugs as much as possible.
- Pharmacy premixes the high-risk medications.
- Unusual or nonstandard doses not be mixed or administered, further, minimizing the need to mix potassium solutions.
2. Education, to re-emphasize the 5 (7) RIGHTS of drug administration: Right patient, right drug, right dose, right route, and right time, and,
Right reason and right documentation.
- Encourage a culture of double-checking of orders with physicians, when high-risk drugs are ordered.
- Promote the identification of high-risk drugs.
3. Concentrated potassium solutions (high-concentrated vials) are removed from ward stock and the night pharmacy.
- Sodium phosphate is substituted for potassium phosphate.
- Monobasic potassium phosphate solution, when needed, is the only solution used.
- With respect to CRRT, concentrated solutions are CRRT-specific or patient-specific medications. Only a small supply (4-6 vials) is available, after pharmacy has closed, for CRRT use only.
4a. Better identification and storage of the various minibags, with large colour-coded labels used.
- Storage and medication areas are reorganized to separate bins, make them more distinct and placed at an appropriate and safe working level.
- The bins for the respective potassium concentrations are colour coded (i.e., with auxiliary fluorescent labels).
- Minibags be labelled and distributed from pharmacy.
- Pharmacy participates in this reorganization and takes ownership of the long-term organization of medication areas.
- Have a magnifying glass available in all medication areas.
4b. Reduce the range of premixed potassium solutions available.
- Restrict access and use of 40-mmol KCL minibags to only ICU patients, whose potassium is being replaced, per ICU potassium protocol. Provided that recommendation 4a is implemented.
- Use multiples of premixed bags for patients whose potassium is not being replaced per protocol.
- Goal should be to standardize the ordering of potassium with universal doses or protocol, concentrations and set infusion rates.
4c. If possible, use oral potassium supplements in lieu of intravenous solutions.
5a. In the FMC site, the "A" medication area is moved away from the unit clerk's desk. At the RGH site, medication area moved or renovated to decrease noise and distractions.
5b. Educate and encourage a do not disturb policy when medications are being mixed.
6. Look-alike and sound-alike drugs are highlighted better.
- Use the same warning labels, consistently, throughout the region.
- "Medication alert" labels be replaced with more specific labels stating either look- alike, sound-alike, different doses or routes.
7. When boluses of potassium are being given the orders and medication be double-checked and charted in QS. This should include patients receiving boluses of 40 mmols or greater or when the ICU K protocol is used.
8a. When medications are mixed in the ICU or on the ward, proper labelling is to include patient name, drug, concentration, date/time and who mixed the medication.
8b. A standardized protocol is developed and implemented for the administration and monitoring of potassium replacement in severe life threatening hypokalemia.
9a. Clear and simple instructions for mixing a solution are included in the region's intravenous therapy manual.
- Goal is to minimize calculations and errors.
- Consideration is given to use of calculation grids in the instruction manuals.
- Revise the pharmacy information section on the internal ICU website, making information more easily available.
10. Consider using satellite pharmacies in areas where high-risk drugs are used.
9b. Use a "keypad box" for the narcotics key at the FMC site. (Currently used at the PLC and RGH.)
11. Immediate changes to the TDS order sets are made.
- Reduce the options; i.e., solutions, concentrations, volumes and rates available for ordering potassium.
- Promote the cultural changes necessary to reduce the use of verbal orders for all high-risk drugs. General/ICU
- Introduce barriers when ordering potassium to prevent duplicated or multiple potassium orders for an individual patient.
- Implement KCL protocols with appropriate inclusion and exclusion criteria, time limits or termination points are developed for non-ICU patients. Include in the protocol links to serum creatinine and previous potassium doses (similar to current Coumadin order sets in TDS).
- Tables showing estimated potassium deficits and rate of replacement are included in the protocols.
About the Author
Rosmin Esmail, MSc, is the Quality Improvement and Patient Safety Consultant for the DCCM, CHR.
Cheryl Cummings, RN, is an ICU nurse at the Peter Lougheed Hospital, CHR
Deonne Dersch, RPh, is a pharmacist at the Foothills Medical Center, CHR
Greg Duchscherer, RRT, is a clinical development specialist, CHR
Judy Glowa, RN, BN, is an ICU Clinical Nurse Educator at the Foothills Medical Center, CHR
Gail Liggett, RN, BN, is an ICU/CCU Clinical Nurse Educator at the Peter Lougheed Hospital, CHR
Dr. Terrance Hulme, MD, FRCPC, is an intensivist at the Rockyview Hospital, CHR
Corresponding Author: Rosmin Esmail, Email: email@example.com
*Special thanks to the contribution of the other members of the Patient Safety and Adverse Events Team. They are Dr. Paul Boiteau, Colin Dececco, Judy Duffett-Martin, Alyce Kolody, Bobbi Sheppy, Arkadi Shuman, Teresa Thurber, Doug Vanstaalduine, and Peter Wiesner.
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Depending on the purpose of the analysis, a topic selected for investigation might be a response to a sentinel event or even a near miss that occurred. Alternatively, other tools, such as safety and environmental walkabouts, error reporting, and even customer complaints, may highlight opportunities for analysis. The choice of topic is important; change should not be implemented simply for the sake of introducing change. The topic should be chosen on the basis of data collected for quality assurance and audit, as well as performance problems. Findings from safety walkabouts (in which an observer walks about the department during the working day, trying to identify potential safety hazards) should be examined, in addition to hazard analyses. The root cause analyses from sentinel events should also be examined closely when choosing a topic for FMEA. Brainstorming with other members of the team is often another valuable way to discover other potential issues within a radiology department.
An imaging department has several processes that are amenable to the FMEA process. Examples of these processes in the imaging department include the following: (a) interventional procedures, such as scheduling, performance, and follow-up; (b) communication of results—critical, urgent, and abnormal; (c) patient throughput; (d) specimen labeling, transport, and processing; (e) equipment failures; (f) room utilization; (g) after-hours clinical coverage; and (h) compliance with the National Patient Safety Goals and the Universal Protocol.
Lessons learned from each FMEA process should be disseminated throughout a division, department, or even the hospital. One useful suggestion is to review the process, results, and outcomes from previous departmental FMEAs because these may offer clues to additional processes requiring intervention. For example, if a successful FMEA is undertaken to streamline the scheduling and performance of an outpatient liver biopsy, it is likely that a similar process can be applied to scheduling other procedures or studies.
Review of our department's quality and safety audits showed that patients receiving mechanical ventilation in the intensive care unit were experiencing delays when undergoing MR imaging examinations. We have therefore selected this process to illustrate FMEA (Figs 2–4).
The team should be committed to identifying opportunities for improvement and to implementing and championing change. Team members must be allocated sufficient time and resources to allow the process to be successful because FMEA is known to be both time and resource intensive (8,11,13). For FMEA to succeed, leadership buy-in and support are essential. Leadership must understand that the process is worth the investment of resources and should support the changes implemented by the team.
When FMEA is being applied for continuous improvement, the team is responsible for identifying what process, systems, or procedures can be improved. A team leader, or facilitator, should be chosen who is familiar with and skilled in teamwork and team building. This team leader plays a vital role in facilitating the process. He or she explains the various steps in the FMEA process, controls the progress of the analysis, and assists the team in applying a systems approach when identifying failure mode causes and outlining appropriate actions (8,11). The team leader should be familiar with the FMEA process, and it is advisable for a team leader to attend a practice session elsewhere or a workshop if he or she has not previously done so. Little can substitute for the educational benefits of actual participation in an FMEA. Tool kits provided by the Joint Commission and the U.S. Department of Veterans Affairs National Center for Patient Safety, as well as The FMEA Pocket Handbook (18), are also useful resources for the facilitator and other team members. When the U.S. Department of Veterans Affairs initially introduced HFMEA in August 2001, participants were given a 2-hour prepared training video and interactive question-and-answer sessions (19).
A recorder should also be appointed to document assigned roles and progress. The role of each person on the team should be clearly outlined. To the extent that it is possible, the team should be multidisciplinary, both representative and inclusive. Members of the team should have expertise in the subject matter being investigated. Patient representatives may be included on the team whenever appropriate (6). The team should be visible and receptive to suggestions from all customers.
In a radiology department, both physicians and technical staff should be invited to participate. In our own experience, inclusion of trainees, nurses, modality managers, and any hospital personnel trained in FMEA, including clinical engineers, should be encouraged. Ingredients that we have found particularly helpful include selecting an experienced team leader, training of team members about the process, and allocating time and resources to undertake and complete the work.
A detailed chart of the process should be constructed by the team, thus enabling complete understanding of the individual steps that are involved in the process. This understanding can be achieved by constructing a process map (Figs 2–4), which visually depicts the sequence of related events in the process. A process map is different from a flowchart (which simply displays the process flow graphically) by showing inputs, outputs, and units of activity, as well as decision or action points. The process map is a hierarchical means for illustrating complex processes and includes additional attributes, such as cycle time and delays between stages, responsible persons, inventory, the value or cost added at each step, and wastage. The details of each process and subprocess should be accurate and comprehensive.
We developed a process map to illustrate the sequence of events involved when a patient in the intensive care unit undergoes an MR imaging examination (Figs 2–4). Narrowing the scope of the analysis is important because too broad an approach will result in a lengthy process; too narrow a scope is unlikely to result in meaningful effects. To establish an environment for a successful outcome, the team should focus on those steps that are most amenable to intervention and improvement. Figures 2–4 also illustrate examples of subprocesses in which failures can occur, from the time when a study is ordered through transport of the patient back to the intensive care unit. These subprocesses are then analyzed to determine which are most likely to have an impact on patient throughput.
Next, each of the subprocesses in which potential failure could occur should be identified (Figs 2–4). Then the different ways in which the subprocess can fail should be determined—in other words, identification of the failure modes. A failure mode is anything that could go wrong during the completion of a step in the process (3). In a radiology environment, something could go wrong because of any number of factors, including staffing, local environmental issues, policies and guidelines, poor communication, equipment problems, human error, and missing or misplaced medications. To maximize the number of failure modes identified, the team may use different resources to assess what adverse events have occurred in the past, including the Joint Commission Sentinel Event Alerts, the Institute of Safe Medication Practices, and information from the Food and Drug Administration's databases (15).
The team should also focus on the potential effect of each failure mode, particularly the potential effect on the patient, but also the potential effect on the operation of the department. Harm to the patient is more likely to occur if the failure mode involves a step in the process immediately before patient intervention. If the failure occurs earlier in the process, it is more likely to cause disruption to the operation of the department than to cause harm to the patient (3). Likewise, when the time interval between the process steps is short, a failure in a process step will be more likely to result in harm to a patient because the failure may not become apparent by the time the next step is commenced (3).
Each failure mode that is identified should be scored according to its potential for severity and impact. Not every failure mode will result in harm to a patient, but the impacts of a failure may manifest as procedural delays, equipment breakdowns, reductions in patient throughput, and numerous other factors affecting patient care and customer service. Members of the team undertaking the FMEA should estimate the severity and impact of the effect of each failure mode. The higher the ranking (on a scale of 1–10), the more severe is the effect of a potential failure mode. Table 1 shows an example of a scoring scale for the severity of effects (20,21).
In determining the probability of a failure mode occurring, reference should be made to the data from previous adverse events and to the personal experience of the team members. The higher the ranking (scale of 1–10), the more likely it is for the failure mode to occur (Table 2) (20,21).
Next, the team focuses on the probability that a failure mode will be detected (Table 3) (20,21). The higher the ranking (scale of 1–10), the less likely it is that a failure mode will be detected. A failure mode could potentially be detected by personnel working in the department or by the patient, or as an alert in a computer system. If a failure mode is not detected, it is highly unlikely that it will be corrected before the next step in the process, thus increasing the likelihood that the patient will be harmed or that the operation of the department will be disrupted.
The risk priority number (RPN), also referred to as the criticality index, is a quantitative measure used to evaluate and assess a failure mode (22). The RPN is derived from the product of the numeric ratings for severity, probability of occurrence, and detectability described in the previous three paragraphs. The RPNs are then ranked to allow prioritization of the failure modes and to highlight the failure modes that exceed acceptable limits and should therefore be targeted for change. The highest RPNs should be prioritized for corrective action. Regardless of the RPN, attention should always focus on any domain where the severity ranking is high. Those steps with low RPNs (and therefore of low impact in the spectrum of failure) are unlikely to affect the process and should therefore not be prioritized as part of this process.
Table 4 shows how ranking is applied to the process being evaluated in the MR imaging department. In this example, the highest RPNs are assigned to a lost request, a broken fax machine, insufficient clinical data on the request, incorrect MR imaging examination ordered, incorrect patient location information on the request, screening form incorrectly filled out, and nurse filling out form being unsure of MR compatibility of devices.
The number of failure modes selected will depend on several factors, including the availability of resources, the mission and priorities of a department, the potential consequences of a failure, including financial implications, and the degree of risk to which patients are subjected. Note that there are no standard rules with regard to the number of failure modes that should be selected for corrective action (23). For practical purposes, in some studies, investigators have arbitrarily focused on the five highest RPNs (6,24). Other investigators have calculated the mean RPN and then focused their improvement efforts on the failure modes with RPNs that were more than the mean (25). Burgmeier (9) proposed a cutoff RPN value and proposed that all failure modes with RPNs that are more than the cutoff RPN should be tackled, regardless of the likely effect that implementing change would have.
Before the team can develop an appropriate action plan outlining the best way to improve the process, an important step is identifying the root cause or causes of each of the failure points. A root cause analysis is a particularly useful tool with which to commence the analysis of each of the failure points. Within the team, there may be many differing opinions as to the root causes of problems. With the use of the cause-and-effect diagram (also referred to as the fishbone diagram), the team setting is ideal to facilitate brainstorming to capture all of the individual ideas. The basic fishbone diagram allows the identification and categorization of the factors contributing to a problem (eg, incorrectly filled-out screening form) (Fig 5).
If a failure mode is likely to occur, evaluate all contributors to see which can be eliminated. Whenever possible, verification steps or checks should be inserted into the process. An excellent example of a verification step is the preprocedure time-out. This time-out is routinely carried out immediately before a procedure and includes all members of the team who are involved in the procedure—usually a technologist, a nurse, and a radiologist. All three people must together verify the patient's name, date of birth, and identification number, as well as the procedure that is planned and the patient's coagulation profile and allergies. The consent form, request form, and the patient's identification bracelet are all used to verify the patient's identity.
If an event is likely to cause harm to a patient and this cannot be avoided, staff should be trained to recognize and manage the early warning signs, and processes should be put in place to facilitate the detection of these signs. The detection and management of a severe allergic reaction to intravenous contrast material provide an example of a serious event that cannot be completely avoided, even with routine use of a preprocedure questionnaire filled out by patients to identify risk factors. When a contrast reaction occurs, responsible staff should know how to detect and manage the reaction and how to call for help. This responsibility includes staff being compliant with institutional training requirements for advanced cardiovascular life support. Other checks that can be inserted into this process include the ready availability of alarms and visual cues and the presence of functioning crash carts, which should be stocked with all of the relevant labeled and unexpired medications. If an event is unlikely to be detected, alarms and alerts should be installed to facilitate detection, along with educational programs to train all staff who may be involved.
Table 2 Occurrence Rating Scale of Failure ModesClick image to enlarge
Table 3 Detection Rating Scale of Failure ModesClick image to enlarge
Table 4 Evaluation of the Severity Score, the Probability of Occurrence Score, and the Probability of Detection ScoreClick image to enlarge
Once the major contributors to a failed process have been identified, strategies should be developed and implemented to prevent subsequent occurrence (Table 5). Whenever possible, such an implementation plan should include (a) specific corrective action items, coupled with defined outcome metrics and timelines, and (b)