Medicine Is an Open Book Exam
A 19-year-old previously healthy female presented to the emergency room after being found unresponsive at home in the late evening. Emergency medical service personnel noted pinpoint pupils and administered two doses of Narcan without any response. There was no past history of illicit drug use or alcohol abuse, and she was taking no prescription medications.
After arrival in the ER, the patient suffered a seizure lasting three minutes. A head CT scan was normal. A drug urine toxicity screen returned as “positive-unconfirmed” for opiates. Abnormal findings included a heart rate of 152, respiratory rate of 21, and a white blood count of 16,800. Arterial blood gas (ABG) revealed a pH of 7.5, pCO2 of 20 and HCO3 of 15.6 (normal values: pH 7.4, pCO2 40, HCO3 23–28).
The following morning, the patient was able to open her eyes and move all four extremities, but she was unable to communicate verbally. The working diagnoses included altered mental status, seizure, rule out encephalitis, and possible aspiration. The patient was treated with ceftriaxone and acyclovir. A neurologist reported lethargy, equal pupils, and movement of all four extremities to painful stimuli.
The next day the patient remained tachypneic with a respiratory rate of 26 and a heart rate in the 140s. She was transferred to a tertiary care center, where she was reported to be unresponsive and intubated. Her ABG demonstrated a marked acidosis. She was treated for the suspected diagnosis of salicylate toxicity with intravenous bicarbonate but died the same day. The postmortem toxicology report confirmed the diagnosis of acute salicylate intoxication.
The physicians managing this challenging patient missed the diagnosis of acute salicylate poisoning, thus delaying the opportunity for therapeutic intervention and increasing the likelihood of a tragic outcome. This case is not unique. In a study of 73 consecutive adults with salicylate intoxication, 27 percent were undiagnosed for as long as 72 hours after admission.1 An earlier diagnosis in this particular patient with altered mental status and salicylate poisoning could have resulted in management that included urgent hemodialysis.2
Salicylate intoxication is an uncommon event that caused 63 deaths in the United States in 2007.3 It is reasonable to infer from this statistic that none of the physicians involved in this case prior to the patient's transfer to the tertiary hospital had ever encountered a patient with severe salicylate intoxication before—which helps to explain their failure to suspect that diagnosis. Furthermore, no physician can even begin to remember in totality the volumes of information learned in medical school and training. In short, physicians over time forget information they have learned. Studies have shown an inverse correlation between the number of years since internal medicine board certification and the knowledge base of practicing internists.4 This finding has been corroborated in other specialties as well.5
Many highly competent physicians may not have initially considered salicylate poisoning in this patient on the basis of the clinical presentation alone. The initial ABG showed an acute combined respiratory alkalosis and a metabolic acidosis. This complex metabolic derangement could not be explained by the working diagnoses of opiate poisoning or central nervous system infection, but it was consistent with salicylate poisoning, which causes a respiratory alkalosis due to stimulation of the respiratory center followed by a metabolic acidosis due to the accumulation of organic acids. Thus, an important clinical finding was not adequately explained or pursued.
Multiple studies have evaluated the processes involved in raising and seeking answers to clinical questions. An illustrative report6 identified that five steps are involved: The physician (1) recognizes an uncertainty, (2) formulates a question, (3) pursues an answer, (4) finds an answer, and (5) applies the answer to patient care. A lack of time and the belief that the search would not yield useful results were the main reasons given for not pursuing answers.
Other studies have demonstrated that doctors tend to underestimate their need for assistance with diagnosis and treatment in daily practice. In one such study, physicians estimated that they needed patient-related information once a week when they actually needed help with the management of six patients per half day of clinic.7
Physicians are more likely to use an online resource when they believe that a definitive answer exists and that the information can be obtained quickly.7 Point-of-care access to information is particularly critical in the emergency department, where physicians do not have the luxury of multiple follow-up patient visits to help them diagnose and treat serious disorders.
Physician concerns about barriers to accessing information and time constraints are largely unfounded. An online search by the author for the causes of respiratory alkalosis and/or hyperventilation in resources such as UpToDate, DynaMed, MD Consult, eMedicine, PubMed, and even Google would have provided a comprehensive differential diagnosis including salicylate poisoning in a few minutes.
Similarly, a study of 70 internists at an academic medical center showed that a partial or full answer to a clinical question was obtained in 83 percent of UpToDate searches requiring an average time per search of 241 seconds.8
Point-of-care knowledge tools not only save time, but they also lead to changes in management that improve efficiency and patient safety. As a result, the tools should be considered indispensable for practicing medicine. While there are several point-of-care resources, UpToDate (www.uptodate.com) is probably the best known. It is used by over 410,000 physicians and accessible in 12,000 hospitals and clinics, including 89 percent of academic medical centers in the United States. The content is developed by more than 4,500 authors, editors, and peer reviewers, representing a who’s who in primary and subspecialty care. It is comprehensive, easily navigated, regularly updated, extensively peer reviewed, and marries the best of evidence-based medicine with practical wisdom from experienced clinicians.
The practice of medicine is an open book examination. Physicians are trained to recognize physiologic abnormalities such as, in this case, severe acid-base disorders. Physicians are expected to formulate a comprehensive differential diagnosis for complex clinical situations that are encountered both in the office and in the hospital. Online evidence-based resources at the point of care are essential in doing so. The use of an electronic knowledge and decision support system to answer clinical questions makes it possible for all physicians to improve quality of care and patient safety.