Patient Safety Advisory Reprinted from the PA-PSRS Patient Safety Advisory—Vol. 1, No.4 (December 2004) Produced by ECRI & ISMP under contract to the Pennsylvania Patient Safety Authority Early Discharge from the ED P A-PSRS has received several reports in which patients were discharged too soon after presenting to the Emergency Department (ED) with poisoning. with ethylene glycol poisoning would be tempered by the concomitant alcohol ingestion. All diagnostic tests, including the physical exam, repre- Case #1: A four year-old patient presents to the ED with sent a “snapshot” of the patient’s condition at a single the mother after having ingested a large number of moment in time. That condition may change quickly anticonvulsant pills prescribed for an adult; the patient and dramatically. While clinicians may understand this appears asymptomatic at presentation. The ED physi- at an intellectual level, they may, like any person, be cian orders a test which measures the level of the drug victims of well-known cognitive biases. One form of in the patient’s blood; this test comes back in the nor- cognitive bias described by Cook and Woods that may mal therapeutic range. The patient is then discharged have played a role in both of these cases is treating a but returns to the ED unresponsive several hours later. dynamic situation as static.3 The patient ultimately recovered without sequelae. Other forms of cognitive bias may also have played a Case #2: A patient presents to the ED following a sui- role. For example, in the first case, the physician may cide attempt in which he ingested ethylene glycol (i.e., have developed a false sense of security from the antifreeze) along with several alcoholic beverages. He blood test result’s being “in the normal therapeutic is asymptomatic on presentation, and initial laboratory range.” While the test suggested that at that time the tests are negative. The patient is transferred to a psy- patient did not have toxic levels of the drug circulating chiatric facility for evaluation before the physician re- in the blood stream, the concept of the therapeutic ceives the result of another diagnostic test showing a range was irrelevant for this patient, who was not pre- very high ethylene glycol level. The patient required scribed this drug and was not taking a stable daily urgent dialysis. dose. The physician surely reviews dozens of test re- sults every day, which are typically presented with ref- In both cases, the patients presented as asymptomatic erence values that constitute the normal range for and presumably remained asymptomatic at discharge. each parameter tested. That the lab test was inter- Also, both involve scenarios in which the pharmacoki- preted as “normal” may have framed the clinical situa- netics of the ingested substances result in a delay in tion in a way that downplayed its critical nature. This is presentation of the signs and symptoms of toxicity. consistent with the “framing effect,” in which one’s in- terpretation of information is influenced by the form in In Case #1, the drug the patient ingested has a variable which it is presented.4 rate of metabolism and a long half-life. The Patient Safety Officer at this facility indicates that the pharma- The ethylene glycol case is suggestive of confirmation cokinetics of the particular drug ingested were not bias—a tendency to selectively perceive information taken into account. Without holding the child for obser- consistent with our prior beliefs and to discount or vation and taking at least a second blood level, there avoid information that is inconsistent with those be- was no way to know whether the drug level was in- liefs.5 The physician seems to have ordered a range of creasing or decreasing at the time of examination. tests during the initial evaluation. Presumably, he or In Case #2, the patient likely failed to develop classic signs of toxicity on some standard lab tests because he This article is reprinted from the PA-PSRS Patient Safety Advisory, Vol. 1, No. ingested alcoholic beverages along with the ethylene 4—December 2004. The Advisory is a publication of the Pennsylvania Patient glycol. Ethanol (the alcohol found in alcoholic bever- Safety Authority, produced by ECRI & ISMP under contract to the Authority as part of the Pennsylvania Patient Safety Reporting System (PA-PSRS). ages) is one treatment for ethylene glycol poisoning. The ethanol in the alcoholic beverages likely sup- Copyright 2004 by the Patient Safety Authority. This publication may be re- pressed metabolism of the ethylene glycol enough for printed and distributed without restriction, provided it is printed or distributed in the patient to test negative for acidosis and fail to de- its entirety and without alteration. Individual articles may be reprinted in their entirety and without alteration provided the source is clearly attributed. velop an anion gap characteristic of ethylene glycol poisoning.1,2 The physician may not have considered To see other articles or issues of the Advisory, visit our web site at that the clinical signs and symptoms usually associated www.psa.state.pa.us. Click on “Advisories” in the left-hand menu bar. ©2004 Pennsylvania Patient Safety Authority Page 1 Reprinted from the PA-PSRS Patient Safety Advisory—Vol. 1, No. 4 (December 2004) Early Discharge from the ED (Continued) she believed those tests to be necessary for an adequate diagnosis at that time. That the patient appeared asymptomatic was surely considered as part of the diagnosis, and when initial lab tests re- turned negative they may have “confirmed” a prior belief based on the lack of expected symptomatol- ogy. Not waiting for the ethylene glycol level sug- gests a discounting of potentially relevant and dis- confirming information. Cognitive biases are errors in human decision- making resulting from the heuristics (or “rules of thumb”) we use in everyday life to process informa- tion. These errors have been shown in individuals at all levels of education.6 When performing a root cause analysis of your facility’s Serious Events or Incidents, consider whether cognitive biases may have played a role and whether any systems changes may help to mitigate the risk these biases pose. Protocols or algorithms based on evidence- based rational decision-making processes can pro- vide structure that may minimize these biases. In poisoning cases, poison control centers are at the core of these protocols and algorithms. Notes 1. Ammar KA, Heckerling PS. Ethylene glycol poisoning with a normal anion gap caused by concurrent alcohol ingestion: Impor- tance of the osmolal gap. Am J Kidney Dis. 1996 Jan;27(1):130- 3. 2. Eder AF, McGrath CM, Dowdy YG, et al. Ethylene glycol poi- soning: Toxicokinetic and analytical factors affecting laboratory diagnosis. Clin Chem. 1998 Jan;44(1):168-77. 3. Cook RI, Woods DD. Operating at the sharp end: The com- plexity of human error, 13. In: Bogner, MS, Ed. Human Error in Medicine. Hillsdale (NJ): Lawrence Erlbaum Associates; 1994. 4. Tversky A, Kahneman D. Judgment under uncertainty: Heuris- tics and biases. Science. 1974;185:1124-31. 5. Nickerson RS. Confirmation bias: a ubiquitous phenomenon in many guises. Rev Gen Psychol 1998;2:175-220. 6. Clarke JR. Clinical Surgical Decision Making. In: Rutkow, I.M., ed. Socioeconomics of Surgery. St. Louis: Mosby, 1989:315- 331. Page 2 ©2004 Pennsylvania Patient Safety Authority Reprinted from the PA-PSRS Patient Safety Advisory—Vol. 1, No.4 (December 2004) An Independent Agency of the Commonwealth of Pennsylvania The Patient Safety Authority is an independent state agency created by Act 13 of 2002, the Medical Care Availability and Reduction of Error (“Mcare”) Act. Consistent with Act 13, ECRI, as contractor for the PA-PSRS program, is issuing this newsletter to advise medical facilities of immediate changes that can be instituted to reduce serious events and incidents. For more information about the PA- PSRS program or the Patient Safety Authority, see the Authority’s website at www.psa.state.pa.us. ECRI is an independent, nonprofit health services research agency dedicated to improving the safety, efficacy and cost-effectiveness of healthcare. ECRI’s focus is healthcare technology, healthcare risk and quality management and healthcare environmental management. ECRI provides information services and technical assistance to more than 5,000 hospitals, healthcare organizations, ministries of health, government and planning agencies, and other organizations worldwide. The Institute for Safe Medication Practices (ISMP) is an independent, nonprofit organization dedicated solely to medication error prevention and safe medication use. ISMP provides recommendations for the safe use of medications to the healthcare community including healthcare professionals, government agencies, accrediting organizations, and consumers. ISMP's efforts are built on a non-punitive approach and systems-based solutions. ©2004 Pennsylvania Patient Safety Authority Page 3