and even mysterious to the beginning student. Experienced clinicians often think quickly, with little overt or conscious effort. They differ widely in personal style, communication skills, clinical training, experience, and interests. Some clinicians may find it difficult to explain the logic behind their clinical thinking. As an active learner, it is expected that you will ask teachers and clinicians to elaborate on the fine points of their clinical reasoning and decision making.
As you gain experience, your thinking process will begin at the outset of the patient encounter, not at the end. Listed below are a set of principles that underlie the process of clinical reasoning and certain explicit steps to help guide your thinking as you analyze the information you have compiled. After reading through this section, review the case of Mrs. N, introduced in Chapter 1, and use this as a sample database to practice the process of clinical reasoning and assessment. As with all patients, focus on finding answers to the questions "What is wrong with this patient?" "What are the problems and diagnoses?" To reach these answers, try following the steps discussed below. Then turn to the Assessment and Plan for Mrs. N on pp. 14-18 and compare them to your own insights and clinical thinking.
IDENTIFYING PROBLEMS AND MAKING DIAGNOSES: STEPS IN CLINICAL REASONING_
■ Identify abnormal findings
■ Localize findings anatomically
■ Interpret findings in terms of probable process
■ Make hypotheses about the nature of the patient's problem
■ Test the hypotheses and establish a working diagnosis
■ Develop a plan agreeable to the patient
■ Identify abnormal findings. Make a list of the patient's symptoms, the signs you observed during the physical examination, and any laboratory reports that are available to you.
■ Localize these findings anatomically. This step may be easy. The symptom of scratchy throat and the sign of an erythematous inflamed pharynx, for example, clearly localize the problem to the pharynx. For Mrs. N, the complaint of headache leads you quickly to the structures of the skull and brain. Other symptoms, however, may present greater difficulty. Chest pain, for example, can originate in the coronary arteries, the stomach and esophagus, or the muscles and bones of the chest. If the pain is exertional and relieved by rest, either the heart or the musculoskeletal components of the chest wall may be involved. If the patient notes pain only when carrying groceries with the left arm, the musculoskeletal system becomes the likely culprit. When localizing findings, be as specific as your data allow, but bear in mind that you may have to settle for a body region, such as the chest, or a body system, such as the musculoskeletal system. On the other hand, you may be able to define the exact structure involved, such as the left pectoral muscle. Some symptoms and signs cannot be localized, such as fatigue or fever, but are useful in the next set of steps.
■ Interpret the findings in terms of the probable process. Patient problems often stem from a pathologic process involving diseases of a body structure. There are a number of such processes, variably classified, including congenital, inflammatory or infectious, immunologic, neoplastic, metabolic, nutritional, degenerative, vascular, traumatic, and toxic. Possible pathologic causes of headache, for example, include concussion from trauma, subarachnoid hemorrhage, or even compression from a brain tumor. Fever and stiff neck, or nuchal rigidity, are two of the classic signs of headache from meningitis. Even without other signs such as rash or papilledema, they strongly suggest an infectious process.
Other problems are pathophysiologic, reflecting derangements of biologic functions, such as congestive heart failure or migraine headache. Still other problems are psychopathologic, such as disorders of mood like depression or headache as an expression of a somatization disorder.
■ Make hypotheses about the nature of the patient's problem. Here you will draw on all the knowledge and experience you can muster, and it is here that reading will be most helpful in learning about patterns of abnormalities and diseases, and clustering your patient's findings accordingly. Until you gain broader knowledge and experience, you may not be able to develop highly specific hypotheses, but proceed as far as you can with the data and knowledge you have. The following steps should help:
1. Select the most specific and critical findings to support your hypothesis. If the patient reports "the worst headache of her life," nausea, and vomiting, for example, and you find mental status change, papilledema, and meningismus, build your hypothesis around elevated intracranial pressure rather than gastrointestinal disorders. Although other symptoms are useful diagnostically, they are much less specific.
2. Using your inferences about the structures and processes involved, match your findings against all the conditions you know that can produce them. For example, you can match your patient's papilledema with a list of conditions affecting intracranial pressure. Or you can compare the symptoms and signs associated with the patient's headache with the various infectious, vascular, metabolic, or neoplastic conditions that might produce this kind of clinical picture.
3. Eliminate the diagnostic possibilities that fail to explain the findings. You might consider cluster headache as a cause of Mrs. N's headaches, but eliminate this hypothesis because it fails to explain the patient's throbbing bifrontal localization with intermittent nausea and vomiting. Also, the pain pattern is atypical for cluster headache—it is not unilateral, boring, occurring repetitively at the same time over a period of days, nor is it associated with lacrimation or rhinorrhea.
4. Weigh the competing possibilities and select the most likely diagnosis from among the conditions that might be responsible for the patient's findings. You are looking for a close match between the patient's clinical presentation and a typical case of a given condition. Other clues help in this selection, too. The statistical probability of a given disease in a patient of this age, sex, ethnic group, habits, lifestyle, and locality should greatly influence your selection. You should consider the possibilities of osteoarthritis and metastatic prostate cancer in a 70-year-old man with back pain, for example, but not in a 25-year-old woman with the same complaint. The timing of the patient's illness also makes a difference. Headache in the setting of fever, rash, and stiff neck that develops suddenly over 24 hours suggests quite a different problem than recurrent headache over a period of years associated with stress, visual scotoma, and nausea and vomiting relieved by rest.
5. Finally, as you develop possible explanations for the patient's problem, give special attention to potentially life-threatening and treatable conditions such as meningococcal meningitis, bacterial endocarditis, pulmonary embolus, or subdural hematoma. Here you make every effort to minimize the risk of missing conditions that may occur less frequently or be less probable but that, if present, would be particularly ominous. One rule ofthumb is always to include "the worst case scenario " in your list ofdifferential diagnoses and make sure you have ruled out that possibility based on your findings and patient assessment.
■ Test your hypotheses. Now that you have made a hypothesis about the patient's problem, you will usually want to test your hypothesis. You are likely to need further history, additional maneuvers on physical examination, or laboratory studies or x-rays to confirm or rule out your tentative diagnosis or to clarify which of two or three possible diagnoses are most likely. When the diagnosis seems clear-cut—a simple upper respiratory infection or a case of hives, for example—these steps may not be necessary.
■ Establish a working diagnosis. You are now ready to establish a working definition of the problem. Make this at the highest level of explic-itness and certainty that the data allow. You may be limited to a symptom, such as "tension headache, cause unknown." At other times, you can define a problem explicitly in terms of its structure, process, and cause. Examples include "bacterial meningitis, pneumococcal," "subarachnoid hemorrhage, left temporoparietal lobe," or "hypertensive cardiovascular disease with left ventricular enlargement and congestive heart failure."
Although medical diagnosis is based primarily on identifying abnormal structures, altered processes, and specific causes, you will frequently see patients whose complaints do not fall neatly into these categories. Some symptoms defy analysis, and you may never be able to move beyond simple descriptive categories such as "fatigue" or "anorexia." Other problems relate to the patient's life, rather than to the body. Events such as losing a job or loved one may increase the risk of subsequent illness. Identifying these events and helping the patient develop coping strategies are just as important as managing a headache or a duodenal ulcer.
Another increasingly prominent item on problem lists is Health Maintenance. Routinely listing this category helps you track several important health concerns more effectively: immunizations, screening measures (e.g., mammograms, prostate examinations), instructions regarding nutrition and breast or testicular self-examinations, recommendations about exercise or use of seat belts, and responses to important life events.
■ Develop a plan agreeable to the patient. You should identify and record a Plan for each patient problem. Your Plan will flow logically from the problems or diagnoses you have identified and specify which steps are needed next. These steps range from tests to confirm or further evaluate a diagnosis, to consultations for subspecialty evaluation, to additions, deletions, or changes in medication, to arranging a family meeting. You will find that you will follow many of the same diagnoses over time; however, your Plan is often more fluid, encompassing changes and modifications that emerge from each patient visit. The Plan should make reference to diagnosis, therapy, and patient education.
Before finalizing your Plan, it is important to share your assessment and clinical thinking with the patient and seek out his or her opinions, concerns, and willingness to proceed with any further testing or evaluation. Remember that patients may need to hear the same information multiple times and ways before they comprehend it. Your relationship with the patient will be enhanced if the patient is an active participant in the plan of care.
H The Case of Mrs. N: Assessment and Plan_
As you study the Assessment and Plan for Mrs. N, think carefully about the clarity and organization of the clinical record. When creating a record, you do more than simply list the patient's story and your physical findings. You must review and organize your data, evaluate the importance and relevance of each item, and construct a clear, concise, yet comprehensive report. At first, it will be challenging to clearly and logically organize your patient assessment. Let the patient's story and symptoms serve as guides, examine the appropriate areas of the body, and apply the steps of clinical reasoning to deepen your knowledge, judgment, and clinical acumen.
Using Mrs. N's record, begin to make a checklist of the features of a good medical record. Later, compare your list with the checklist on pp. 796-798. The following questions may help: Are the data easy to follow, orderly, and presented in a readable format? Is there sufficient detail, both positive and negative, to formulate an Assessment and Plan? Is there excess repetition of information or redundancy? Is the tone professional, avoiding disapproving or moralizing comments?
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