ment (ED) with the complaint of shortness of breath. She was noted to be ... pital, Brown University School of Medicine, Providence, Rhode. Island. Address for ...
326
SIDEDNESS ERROR
Shapiro et al. • SIDEDNESS ERROR
Profiles in Patient Safety: Sidedness Error MARC J. SHAPIRO, MD, PAT CROSKERRY, MD, PHD, STEVEN FISHER, MD
Abstract. This case describes a 45-year-old woman with significant respiratory distress secondary to a left-sided pleural effusion that mandated an urgent thoracentesis. An adverse event occurred when the physician performed the procedure on the incorrect side of the patient. Results of the incident investigation followed by a discussion of medical errors models, common errors types, human factors considera-
CASE SCENARIO A 45-year-woman with hypertension and chronic renal failure presented to the emergency department (ED) with the complaint of shortness of breath. She was noted to be hypertensive and hypoxic and was placed in a critical care bed. The patient had an immediate electrocardiogram (ECG), which demonstrated left ventricular hypertrophy but no acute ST-segment changes. A chest x-ray (CXR) was performed and returned to the nurse, who hung it on the view box for the physicians to review. The emergency medicine (EM) attending physician reviewed the film and put his interpretation of mild congestive heart failure and ‘‘right pleural effusion’’ on the chart. The EM resident subsequently reviewed the film, prior to seeing the attending physician’s interpretation, and made the same interpretation. The team of physicians discussed the case, but did not review the x-ray together, and decided to perform an urgent thoracentesis due to the patient’s compromised respiratory status. Prior to the thoracentesis the x-ray film was brought to the radiology reading
From the Department of Emergency Medicine, Rhode Island Hospital, Brown University School of Medicine (MJS, SF), Providence, RI; and the Department of Emergency Medicine, Dartmouth General Hospital Site, Dalhousie University (PC), Halifax, Nova Scotia, Canada. Section editors: Pat Croskerry, MD, PhD, Department of Emergency Medicine, Dartmouth General Hospital Site, Dalhousie University, Halifax, Nova Scotia, Canada; and Marc J. Shapiro, MD, Department of Emergency Medicine, Rhode Island Hospital, Brown University School of Medicine, Providence, Rhode Island. Address for correspondence and reprints: Marc J. Shapiro, MD, Department of Emergency Medicine, Rhode Island Hospital, Brown University, School of Medicine, 593 Eddy Street, Providence, RI 02903. Fax: 401-444-6662; e-mail: mshapiro@ lifespan.org A related commentary appears on page 324.
tions, and conditions that contribute to error are presented. Pertinent case-specific and general concepts of a system approach to reduce this type of medical error are discussed, and educational recommendations are offered. Key words: sidedness error; medical error; patient safety. ACADEMIC EMERGENCY MEDICINE 2002; 9:326–329
room and the resident physician concurred with the ED reading. There was a discussion about ultrasound to aid in localization of the effusion, but the radiology resident thought this was unnecessary, given the size of the effusion. The patient subsequently underwent a right-sided thoracentesis with return of a small amount of dark blood, and the procedure was terminated.
INCIDENT INVESTIGATION Subsequent root cause investigation revealed that the x-ray technician had placed a sticker on the film, which correctly identified the patient’s orientation, but did not place a radiographic (opaque) marker on the film. The first display of the film on the viewing box was erroneously reversed, and therefore would have hidden the sticker. This disorientation apparently persisted when the film was taken to the radiology reading room and shown to the radiology resident.
DISCUSSION The case illustrates very clearly the trajectory a latent error can take in the course of a patient’s management. It involves a classic error in medicine, that of the sidedness of the patient. As patients usually have symmetrical sides, the potential always exists for confusing them, especially when performing blind procedures. Reports on sidedness errors are legion and often associated with a catastrophic outcome. Latent refers to this dormant potential, the adverse consequences of which may be realized only when conditions become right for their expression. The concept is illustrated very clearly in Reason’s Swiss cheese model,1 Figure 1, in which the holes in any one ‘‘slice’’ represent active failures or latent conditions, which are continually shifting. The hole in
ACADEMIC EMERGENCY MEDICINE • April 2002, Volume 9, Number 4 • www.aemj.org
327
Figure 1. The Swiss cheese model of how defenses, barriers, and safeguards may be penetrated by an accident trajectory. Reproduced with permission from the BMJ Publishing Group, from: Reason J. Human error: models and management. BMJ. 2000; 320:768–70.
one ‘‘slice’’ is not likely to be consequential; however, the momentary alignment of multiple holes can result in an adverse event. In the case scenario described here, this latent error actually began with the urgent condition of the patient. The call for a portable CXR resulted in a departure from the set protocol that exists for ambulatory patients, who usually receive their examinations within the radiology department. The radiology technician did not follow the usual procedure of placing a radiographic, opaque marker on the film (which would be visible whichever way the film was oriented on the viewing box) and placed a sticker on the film instead. When the nurse hung the film on the viewing box, a compound error occurred made up of three parts: 1) The cardiac silhouette was confusing and actually shifted to the right, resulting in the nurse’s pattern recognition error. 2) The nurse was not accustomed to displaying x-rays on the viewing box, resulting in an error due to unfamiliarity and inexperience, but it was also an error arising from performing a task that lies outside the normal scope of nursing. This was an out-of-role error, the nurse having initiated the procedure of x-ray interpretation in which she was not trained or experienced. 3) The incorrect hanging of the film on the display box hid the sticker identifying the correct side—this was a system-design type of error. The designer (radiology technician) intended the sticker to be seen, but the simple error of reversing the film obscured it. This compound error critically set the stage for what followed. When the emergency physician saw the film on the viewing box, he made the assumption that it had been correctly displayed, presumably because he believed that another physician or radiology technician had hung the film, i.e., there was an assumed, intrinsic credibility or correctness to the film’s display because only those trained in x-ray
procedures usually perform this function. The usual (and critical) step of taking the film out of the envelope and orientating it on the viewing box was bypassed. Had the emergency physician known that someone inexperienced had hung the film, he might have questioned the orientation. In his interpretation of the x-ray, he attempted to pattern-match the right-sided density to his templates for such findings, and erroneously concluded it was a right-sided pleural effusion. Given that this was based on only radiographic information, and with no clinical or other corroboration, the diagnosis was premature. The EM resident independently arrived at the same conclusion, committing the same error of interpretation. In addition, deference to authority, a reluctance to question assumptions, and possibly barriers to communication against the authority gradient can be impediments to error prevention in cases such as this one. These human factors considerations can be addressed through teamwork training, which empowers and encourages all team members to cross-monitor team members’ actions and assert a corrective position when they witness a potential error. In order for the radiology resident to concur with this interpretation, it is likely that the film was again incorrectly oriented when it was taken to the radiology reading room. This suggests that a physician, either the attending or the resident, placed it on the radiologist’s viewing box or handed it, incorrectly oriented, to the resident. In seeking a radiologist’s consultation, some physicians may inappropriately offer their interpretations first. We do not know whether this happened in this case, but if this did occur there is a greater chance that the bias would have been perpetuated. Thus, the concurrence by the radiology resident may have been a copying type of error, a compliance type error or perceived pressure to concur with an authority figure (if the attending was present), or
328
SIDEDNESS ERROR
simply a group pressure error.2 Studies have shown that radiologists’ interpretations of radiographs can be influenced by prior information,3 and this may be more pronounced in the inexperienced. Whatever the explanation, a potential barrier to the error was overcome and it continued on its trajectory. The overreliance on diagnostic studies for identification of pathology contributed to the omission of routine physical exam to confirm location of the pleural effusion. A further barrier to the error was also overcome when the use of ultrasound to help localize the effusion was rejected. By this stage, there was considerable anchoring4 on the original diagnosis, as well as confirmation bias.5 The size of the effusion was seen as sufficiently compelling to obviate any need for potentially disconfirming maneuvers (physical examination, ultrasound). Alternatively, the ultrasound may have been seen as unduly delaying definitive therapeutic action, or the clinicians may have experienced a production pressure because of patient volume. The errors of overconfidence,6 and group pressure/compliance2 may also have played a role here. On the surface, this case may seem to be a simplistic error, the equivalent of wrong-site surgery. Thus, it is extremely easy to blame individuals and, in the process, make a further mistake, the fundamental attribution error.7 Instead, if we perform cognitive and root cause analysis, a more complex system failure is revealed with many contributing factors. These failures arise from two sources.2 The first are error-producing conditions (EPCs). Examples in this case are the urgent/ emergent imperative to action with this patient, the change in procedure for identifying the x-ray film, the out-of-role action by the nurse in displaying the film, inexperience of both the emergency and radiology residents, lack of veracity checks for invasive procedures, and the myriad other ambient interruptions and distractions that occur in most EDs.8–10 The second are violation-producing conditions (VPCs), which involve more social and motivational problems and are, therefore, less visible. Possible examples here are copying behavior, compliance with authority gradients, gender (males are 1.4 times more likely to engage in violations than females), and the perceived authority/expertise of the radiology resident regarding the suggestion to do an ultrasound. Cognitive errors arise from both EPCs and VPCs. Practical strategies for dealing with these sources of error are reviewed, in detail, in an excellent chapter by Reason.2 Modern approaches to error management demonstrate that meaningful and productive error reduction can be accomplished only through the creation of safety systems to prevent the occurrence of an error.2 In addition, monitoring that makes
Shapiro et al. • SIDEDNESS ERROR
errors more visible before injury occurs gives the clinician more options for successful recovery. Individuals and teams should be alert to these conditions and to maintain accountability for their actions, but the system design itself should also provide a safety net because human error, even by the most highly skilled individuals, is inevitable. Safety systems to ensure proper labeling of x-rays and procedures for verifying location for blind procedures were inadequate in this case. The remaining discussion focuses on factors contributing to this error occurrence, which have general applicability in the prevention of other adverse events.
COGNITIVE FACTORS Anchoring bias4 refers to the tendency to perceptually lock onto salient factors in the initial presentation, often disproportionately and to the exclusion of other diagnostic possibilities. It is compounded by confirmation bias,5 the tendency to persist with the initial hypothesis despite the existence of contrary information such as, in this case, the heart shadow abnormality. Rather than seek out evidence that supports an early hypothesis, it is often a more powerful strategy to look for tests or procedures to disconfirm it. This combination of biases probably represents one of the most important types of cognitive error contributing to misdiagnosis in EM, and leads in this case to premature diagnostic closure.11,12 Another example of anchoring bias and premature diagnosis would be in the case of the loud demanding patient making a scene at triage, leading to the assumption that the individual is likely to be intoxicated or psychotic, but is later found to have significant pain from a kidney stone. Clearly, the interaction between the EM resident and the radiology resident is important here. Any exchange of ideas before the radiology resident has seen the film can introduce bias and influence outcome. It has been demonstrated that simply writing a provisional interpretation on the x-ray envelope can significantly influence the radiologist’s interpretation of the film.3 This priming or pre-shaping influence has been referred to as ascertainment bias.13 Thus, when seeking a radiologist’s opinion, it is preferable to delay clinical information, and especially one’s own interpretation, until after the film has been viewed by the radiologist, or until the radiologist requests it. A more formal and detailed understanding of cognition and the predictable cognitive errors would be invaluable in the training of clinicians.8,14 This body of knowledge is not routinely incorporated into either undergraduate or postgraduate training presently, but certainly should receive more attention. It should be routinely built into
ACADEMIC EMERGENCY MEDICINE • April 2002, Volume 9, Number 4 • www.aemj.org
any medical error reduction program.15 (There will be an ongoing effort to illustrate these concepts through future cases presented in this ‘‘Profiles in Patient Safety’’ feature.)
HUMAN FACTORS Aviation data have demonstrated that 70% of incidents involve human factors, and the same is likely to be the case in medicine. In a needs-analysis of improved teamwork to reduce medical error, Risser et al.16 found that the following four team behaviors were all powerful tools to avoid serious errors: 1) cross-monitoring actions of a team, 2) prioritizing tasks for a patient, 3) advocating and asserting a position or corrective action, and 4) identifying an established protocol to be used or develop a plan. In this case, any team member could have advocated for a secondary method to confirm the location of the pleural effusion. Teamwork training curriculum can provide a structure and process for challenging the authority gradient, which is pervasive in medicine. Challenges regarding patient care should be seen as desirable behaviors to prevent medical error and provide high-quality care. The physician is still the team leader and has ultimate authority, but investing all team members in the care of the patient and encouraging situational leadership will improve team performance. Most high-reliability organizations such as nuclear power and aviation have already embraced teamwork training as a method to reduce error, and medicine needs to follow their lead.
PROPOSED SYSTEM CHANGES AND EDUCATION RECOMMENDATIONS FROM THE INCIDENT 1. Uniform radiographic labeling of all x-rays, by universal use of radio-opaque markers on patient cassettes. 2. Written reminder and signature sheet for all thoracentesis kits requiring two physicians to independently confirm the location of the pleural ef-
329
fusion using at least two methods (x-ray, physical examination, or ultrasound). 3. Awareness of and education about error-producing conditions (EPCs) and violation-producing conditions (VPCs). 4. Awareness of and education about cognitive error. 5. Awareness of and education in team dynamics and behavior. To include discussion of the appropriate role for team members and methods for communicating up the authority gradient. References 1. Reason J. Human Error. New York: Cambridge University Press, 1990. 2. Reason J. A practical guide to error management. In: Reason J. Managing the Risks of Organisational Accidents. Aldershot, Hampshire: Ashgate, 1997, pp 125–55. 3. Norman GR, Brooks LR, Coblentz CL, Babcook CJ. The correlation of feature identification and category judgments in diagnostic radiology. Mem Cogn. 1992; 20:344–55. 4. Tversky A, Kahneman D. Judgment under uncertainty: heuristics and biases. Science. 1974; 185:1124–31. 5. Wason PC. On the failure to eliminate hypotheses in a conceptual task. QJ Exp Psychol. 1960; 12:129–40. 6. Lichtenstein S, Fischoff B, Phillips LD. Calibration of probabilities: the state of the art to 1980. In: Kahneman D, Slovic P, Tversky A (eds). Judgment under Uncertainty: Heuristics and Biases. New York: Cambridge University Press, 1982. 7. Heider F. The Psychology of Interpersonal Relations. New York: Wiley, 1958. 8. Croskerry P. The cognitive imperative: thinking about how we think. Acad Emerg Med. 2000; 7:1223–31. 9. Chisholm CD, Collison EK, Nelson DR, Cordell WH. Emergency department workplace interruptions: are emergency physicians ‘‘interrupt-driven’’ and ‘‘multitasking’’? Acad Emerg Med. 2000; 7:1239–43. 10. Croskerry P, Sinclair D. Emergency medicine: a practice prone to error? Can J Emerg Med. 2001; 3:271–6. 11. Kassirer JP, Kopelman RI. Learning Clinical Reasoning. Baltimore: Williams and Wilkins, 1991. 12. Kovacs G, Croskerry P. Clinical decision making: an emergency medicine perspective. Acad Emerg Med. 1999; 6:947–52. 13. Greenhalgh T. Narrative based medicine in an evidence based world. In: Greenhalgh T, Hurwitz B (eds). Narrative Based Medicine. London: BMJ Books, 1998. 14. Redelmeier DA, Ferris LE, Tu JV, et al. Problems for clinical judgment: introducing cognitive psychology as one more basic science. Can Med Assoc J. 2001; 164:358–60. 15. Croskerry P, Wears RL, Binder LS. Setting the educational agenda and curriculum for error prevention in emergency medicine. Acad Emerg Med. 2000; 7:1194–200. 16. Risser DT, Rice MM, Salisbury ML, et al. The potential for improved teamwork to reduce medical errors in the emergency department. Ann Emerg Med. 1999; 34:373–83.
