Improving Patient Care by Locating and Implementing Evidence-Based Clinical Guidelines

Question: What is the evidence-based method of diagnosing and treating condition X?

Students may be unaware that evidence-based consensus guidelines exist for many conditions. Open this discussion by asking the student how he or she would manage the diagnosis or treatment of the patient. Ascertain the student’s existing knowledge about the condition. Often, effective teaching is provided by coaxing the student to recognize his or her knowledge deficit or frank misconception and then leading the student to find the best information on that topic (Table 8.1). A great website for this situation is sponsored by the National Guideline Clearinghouse (guidelines.gov). The American College of Emergency Physicians publishes its clinical policies at acep.org/clinicalpolicies (perform a Google search on “ACEP clinical policies”). Medical search engines such as PubMed allow restriction of searches to practice guidelines using a “Limits” feature.

Table 8.1 Suggested websites for locating and implementing evidence-based clinical guidelines.

National Guidelines Clearinghouse	guidelines.gov
American College of Emergency Physicians	acep.org/clinicalpolicies
US National Library of Medicine	www.pubmed.gov

Performing an Effective and Efficient Evidence-Based Medicine Literature Search for Clinically Meaningful Answers During a Busy Shift

Question: What is the quality of evidence for treatment of condition X with treatment Y or for diagnosis of condition X with modality Y?

Key to the future success of our students as physicians is their ability to find evidence efficiently and to evaluate it for internal and external validity. This is not just the domain of journal club. In fact, the importance of evaluating the quality of evidence may be highlighted when an important clinical decision rests on the outcome of the student’s analysis. Tell the student that you are relying on him or her to weigh the evidence and commit to a course of action. This transforms the search from a hypothetical activity to one with clinical relevance and involves the student in the patient’s care.

Students need to understand how to perform a rapid and appropriately targeted search in the ED and to evaluate the applicability of the research findings to their patients. While practice guidelines can be the source for many diagnostic and therapeutic decisions, they can be outdated or biased by industry sponsorship or they might not exist for the condition in question. Some great exercises include teaching a student to use the “Limits” field of search engines such as PubMed, OVID, and Google Scholar (www.scholar.google.com). Prefiltered specialty databases such as Best Evidence Topics from the British Medical Journal, Cochrane database, ACP Journal Club, and Emergency Medical Abstracts compare favorably with broader search engines in identifying clinically useful evidence [10].

Many exercises are possible using medical search engines. Ask the student to structure the clinical question using the Patients/Interventions/Comparisons/Outcomes (PICO) model, demonstrated at the Centre for Evidence-Based Medicine (CEBM) web page (cebm.net) under the heading “EBM tools” → “Asking Focused Questions.” Demonstrate to the student that the search term myocardial infarction aspirin retrieves 5941 records in PubMed (pubmed.org), while limiting the same search to “human,” “English,” and “Randomized Controlled Trial” and adding the term mortality reduces the number of hits to 398. Adding the search term emergency reduces the number of retrieved studies to 17, a reasonable number for the practicing physician to peruse during a clinical shift in the ED. Demonstrate to the student an important corollary: a restricted search strategy can miss important information. For example, the search listed above misses the sentinel ISIS-2 study [11], which demonstrated the mortality benefit of aspirin, because this study was not conducted in an ED. To illustrate this point further, ask the student to perform the same search in multiple engines and compare the results. Another exercise to refine the student’s search capability is to pick a target study, such as NEXUS [12] or ISIS-2 [11], and ask the student to answer a related clinical question. An effective search should retrieve the target study, and it may be revealing to the student to experiment with various strategies to see which is most effective in finding clinically relevant evidence. A guide to performing clinically relevant searches was published in the Annals of Emergency Medicine in 2003 and demonstrates several useful strategies that can be reproduced by the student in the ED [10]. In addition, the CEBM website includes excellent tutorials for constructing a search at cebm.net → EBM Tools → Finding the Evidence.

The Journal of the American Medical Association (JAMAevidence.com) has published the Users’ Guides to the Medical Literature, which is a useful reference for the teacher and the student and is divided into important clinical categories such as diagnosis, therapy, and harm. Consider using these categories to highlight an evidence-based medicine (EBM) point, such as pretest probability or internal and external validity. The same site includes electronic versions of the “Rational Clinical Exam” series (with a table summarizing the likelihood ratios (LRs) for physical examination findings in important disease processes such as abdominal aortic aneurysm) and interactive calculators, including number needed to treat (NNT), number needed to harm, sensitivity, specificity, and LRs. These calculators are particularly useful because they allow the teacher and the student to vary parameters such as pretest probability, population size, or disease prevalence and then observe the effect. This site requires a subscription, although many academic emergency physicians may have free access to it through their institution.

The CEBM also has interactive EBM tools that can be used rapidly to demonstrate an educational point, including critical appraisal worksheets and calculators for common useful values such as NNT. Their interactive LR nomogram helps the student visualize the degree of clinical certainty gleaned from a test result (go to cebm.net/index.aspx?o=1161 or to cebm.net and search for “interactive nomogram” using the site’s search bar) (Table 8.2).

Table 8.2 Suggested websites for an efficient evidence-based medicine literature search.

Best Evidence Topics	bestbets.org
Centre for Evidence-Based Medicine	cebm.net
Centre for Health Evidence	www.cche.net
Cochrane Library	cochrane.org
Emergency Medical Abstracts	http://ccme.org
Google Scholar	scholar.google.com
JAMAevidence	jamaevidence.com
PubMed	pubmed.org

Improving Use and Interpretation of Diagnostic Imaging

Questions: Does your patient need imaging? Why? What kind? What findings will you look for? What if the images are normal? What is the radiation risk to the patient?

Understanding the role of diagnostic imaging in emergency conditions is a vital skill for the emergency physician and one that can be divided into several important stages:

1. risk stratifying patients to determine who needs imaging;

2. selecting the diagnostic imaging test appropriate to the condition;

3. understanding the radiation risk of diagnostic imaging and revising the imaging plan appropriately depending on patient factors;

4. understanding the findings on diagnostic images;

5. knowing the limits of diagnostic imaging, thus enabling the physician to recognize when a false-negative result may have been obtained.

First, ascertain which stages of this process the student can already comfortably perform and then engage him or her with learning more about the stages that are unfamiliar. For example, the student may be aware of the NEXUS [12] rule and may be able to determine whether a patient with blunt trauma requires cervical spine imaging. But the student might be unaware of the limitations and capabilities of imaging tests and might plan to perform cervical CT when plain radiography would be sufficient. In addition, the student might be unfamiliar with the systemic evaluation of cervical spine radiographs or unaware of the limited sensitivity of radiographs for fracture. The student might not know when additional imaging is needed to rule out fracture or ligamentous injury or when a cervical collar and follow-up are indicated.

For each of the stages listed earlier, online resources can assist. Introduce the student to clinical decision rules such as NEXUS; the Canadian rules for cervical spine imaging and head CT; the Ottawa ankle, foot, and knee rules; the Pittsburgh knee rule; and the rules for venous thromboembolic disease risk stratification. Discuss the development of clinical decision rules using derivation and validation phases and then ask the student to identify a clinical decision rule relevant to his or her patient’s presentation. A variety of clinical decision rules are available at MDCalc (available at mdcalc.com or perform a Google search on “mdcalc”), some with online calculators. The National Center for Emergency Medicine Informatics (ncemi.org) also provides calculator versions of many of these rules. Teach the student to use and document these rules in the medical record, which is good EBM and good clinical practice for billing and medical decision making. For students who are already quite familiar with clinical decision rules, challenge their thinking by asking about power and precision. These concepts can be illustrated by selecting a clinical decision rule and asking the student to explain the 95% confidence intervals surrounding the point estimate of the rule’s sensitivity. Ask the student “What is the worst-case performance of this rule (lower limit of the 95% confidence interval)? How low might the sensitivity really be? How large would the study population need to be to narrow the confidence intervals to a level acceptable to you to apply this in clinical practice?” Multiple online calculators provide the confidence intervals of a proportion (e.g., http://faculty.vassar.edu/lowry/prop1.html). Under the “Calculators” tab at JAMAevidence.com, a particularly intuitive two-by-two table calculator is available that allows the student to vary the population size, disease prevalence, and false-positive and false-negative rates while observing the effects on sensitivity, specificity, LRs, predictive values, and 95% confidence intervals. Have the student keep the proportions constant while increasing the population 2, 5, 10, or 100 times to observe the effect on confidence intervals.

In many cases, formal clinical decision rules do not exist, but other relevant guidelines can assist in diagnostic decisions. The American College of Radiology (ACR) has published brief evidence-based “Appropriateness Criteria^®” describing the most appropriate diagnostic imaging tests for various clinical scenarios, from right lower quadrant pain to suspected aortic dissection (www.acr.org/ac). Use the site to foster discussion with the student about test selection, sensitivity, specificity, and risks of diagnostic imaging. The ACR Appropriateness Criteria offer a range of variations in clinical presentation, promoting your dialogue with the student about tailoring diagnostic imaging to the particular features of your patient. The clinical policies of the American College of Emergency Physicians also provide evidence-based guidelines on indications for diagnostic imaging in selected clinical scenarios (acep.org/clinicalpolicies), such as suspected pulmonary embolism, blunt abdominal trauma, and suspected appendicitis.

Several websites have useful information demonstrating pathologic images and structured interpretation of imaging tests (Table 8.3). Free searchable archives with annotated radiologic images are offered at mypacs.net. Many useful imaging references, including a series tailored for novices, called Recognizing … a series of short modules designed for beginners, are available at www.learningradiology.com. Incorporate this information clinically by referring the student to a guide to the abnormality in question, such as “Recognizing a pneumothorax,” and asking the student to review this while the patient is undergoing the imaging test. This provides the basis for your discussion on the patient’s test when it is completed.

Radiation risks of imaging studies are discussed in a brief but accessible publication by the International Commission on Radiological Protection, titled Radiation and Your Patient: A Guide for Medical Practitioners (www.icrp.org/docs/Rad_for_GP_for_web.pdf). In addition, this site provides a brief PowerPoint presentation that outlines the risks of radiation during pregnancy (www.icrp.org/page.asp?id=35). Introduce these questions by asking the student, “What will you tell your patient about the risks of the imaging study you are recommending?”

A discussion of pre- and posttest probability and LRs is essential to allow the student to incorporate the diagnostic imaging results, positive or negative, into the clinical plan. Ask the student, “What is the pretest probability of the disease? What is the LR, positive and negative, for the imaging test? What is the posttest probability?” Refer the student to the brief and clear discussion of these topics in the website of the CEBM (perform a Google search on “CEBM likelihood ratio”); the CEBM site also includes an interactive nomogram that allows the student to visualize the interaction of pretest probability and LR. Engage the student to search for the LRs for the imaging study or to calculate LRs from sensitivity and specificity values (described in the CEBM website) (Table 8.2).

Table 8.3 Suggested websites for interpretation of diagnostic imaging.

American College of Emergency Physicians	acep.org/clinicalpolicies
American College of Radiology	acr.org/ac
International Commission on Radiological Protection	www.icrp.org/educational_area.asp
LearningRadiology	learningradiology.com
MDCalc	mdcalc.com
MyPACS	mypacs.net
National Center for Emergency Medicine Informatics	ncemi.org

Enhancing Systematic Interpretation of Electrocardiograms

Question: Interpret this ECG systematically. What electrocardiographic abnormalities are expected in condition X?

The ability to interpret ECGs is clearly a core skill in emergency medicine. The comprehensive online resources that are available can be a springboard for discussions of ECG abnormalities (Table 8.4). This topic is so broad that the student may be overwhelmed by the amount of material available. First, assess the student’s baseline knowledge by asking him or her to perform a routine analysis of an ECG. Identify areas of weakness, for example, an inability to recall the normal QRS duration. Then direct the student to an online resource with a specific question in mind: What is the normal QRS duration? What happens to the QRS complex in a patient with Wolff-Parkinson-White syndrome? The Alan E. Lindsay ECG Learning Center has an outstanding online course in ECG analysis, from beginning to advanced topics, complete with quizzes.

Alternatively, give the student an online ECG to analyze and then compare with the actual patient’s ECG. The ECG Wave-Maven site has an excellent tool for this purpose. It allows the teacher to search the library by diagnosis, and the ECG can be displayed to the student with the answer hidden, promoting a Socratic discussion. Ask the student the following questions: What is the most important ECG abnormality? What is the differential diagnosis of the ECG abnormality? What diagnostic tests might be warranted in response to this ECG? What treatments are appropriate? How is this ECG similar to or different from your patient’s ECG?

Table 8.4 Suggested websites for interpretation of ECGs.

ECG Library	ecglibrary.com
ECG Primer	anaesthetist.com/icu/organs/heart/ecg
ECG Wave-Maven	ecg.bidmc.harvard.edu
The Alan E. Lindsay ECG Learning Center	library.med.utah.edu/kw/ecg/
Wikipedia “ECG”	en.wikipedia.org/wiki/Electrocardiogram

Enhancing Understanding of Drug Toxicity, Interactions, and Treatment

Questions: Does the patient have toxidrome? What is the toxin? What is the toxic dose? Is decontamination helpful? Is an antidote available? What are the toxic effects? Are drug levels useful? What drug interactions must be considered? What disposition is appropriate?

Drug effects, interactions, and toxicology are great areas to explore with a student by using computers. These are topics with a wealth of information not easily remembered, and as the practicing physician will often need to rely on online resources, introducing the student to them teaches not only medical knowledge but also practical skills (Table 8.5). Areas for teaching include toxidromes; pill identification; antidotes and decontamination; toxic effects, including ECG changes associated with ingestions; and recommendations for observation. A fun exercise is to provide the student with an “unknown” pill and ask him or her to identify the potential toxin using an online identification tool. One such tool is drugs.com/pill_identification, an index of pill images searchable by drug name, imprint, shape, and color. Ask the student “If you did not have the pill and could not measure drug levels, how would you predict the type of toxin?” to stimulate a discussion of toxidromes. Common toxidromes are reviewed at uic.edu/com/er/toxikon, with a short series of toxicology cases to test the student’s understanding of toxidromes. The site also poses clinically relevant management questions and answers following brief case presentations. Users can create custom free flash cards and related tests at quizlet.com. Its flash card sets include some toxidromes.

Up-to-date lists of drugs categorized by their risk of QT-interval prolongation and consequent torsades de pointes are maintained at qtdrugs.org. The National Center for Emergency Medicine Informatics maintains a website (NCEMI.org) with multiple clinical calculators, including toxicity nomograms for acetaminophen and ibuprofen. Challenge the student to find drugs with toxicity in the patient’s medication list or to identify potentially important drug interactions. If none exists, create one by suggesting an additional therapy and asking the student to determine the safety of the addition. Alternatively, ask the student to suggest a therapy, keeping drug toxicity in mind. For example, the student might be directed to choose an antibiotic therapy in a patient taking Coumadin, phenytoin, or other drugs with cytochrome P450 metabolism. A free application that can be used to identify drug interactions is available at drugs.com.

Drug safety during pregnancy is an important topic that can be explored using a variety of resources. Ask the student “Would this drug be safe to use in a pregnant patient? How will you answer the patient’s questions about risk and benefit?” Up-to-date and ClinPharm are subscription services available through many medical centers that provide information on pregnancy and lactation risk. In addition, safefetus.com provides a list of medications categorized according to pregnancy risk by the US Food and Drug Administration (FDA). Ask the student to find five drugs that are in the FDA Pregnancy Risk Category X. Review the FDA pregnancy risk categories with the student and pose a scenario involving the potential use of a Category D drug. Ask the student to justify the use of the drug based on potential risk and benefit and to propose a safer alternative therapy.

Toxicity and antidote information is available through Micromedex, a subscription service. In addition, the website http://toxnet.nlm.nih.gov lists industrial and household chemicals along with their toxicity and treatment information. Challenge the student to determine the toxicity of the household products under his or her kitchen sink. Propose a case of pediatric ingestion of a household product and ask the student to manage the case. The limits of research in toxicology can also be a useful topic to explore with the student. This is a good opportunity to have the student search for randomized controlled trials of toxicity and treatment, if only to discover the paucity of evidence.

Table 8.5 Suggested websites for enhancing understanding of drug toxicity.

Drugs.com	drugs.com
QT-interval prolongation	qtdrugs.org
Drugs in pregnancy	safefetus.com
ToxNet drugs and household products	toxnet.nlm.nih.gov

Introducing a Systematic Approach to Describing Skin Lesions

Question: How can a skin lesion be described in terms of color, morphology, pattern, organization, and location?

Skin lesions are a frequent complaint in the ED, and education on this topic is sparse in most training programs. Computer resources can teach the student to characterize a skin lesion systematically to facilitate diagnosis. DermAtlas from the Johns Hopkins University (www.dermatlas.med.jhmi.edu/derm) is a free collaborative archive of dermatologic cases with tools to aid in formulating a differential diagnosis. Provide an image from this database to the student and ask him or her to characterize the lesion by color, morphology, pattern, organization, and body location. With the aid of the online resource, have the student prepare a differential diagnosis for the lesion. As an alternative exercise, describe a dangerous skin lesion, such as palpable purpura, using the systematic approach described earlier. Refer the learner to the online resource to find matching examples of this type of lesion and again ask for the differential diagnosis. Focus the student on life-threatening illnesses with dermatologic manifestations.