Key Clinical Questions
Introduction
Competencies in hospital medicine are classified within three domains of outcomes: cognitive (knowledge), psychomotor (skills), and affective (attitudes). Critical thinkers must have a basic knowledge about the methods of logical inquiry and reasoning (cognitive), some skill in applying these methods (psychomotor), and an attitude predisposed to thoughtful consideration of the problems and subjects that come within the range of one’s experiences (affective). They must recognize the problems confronting patients; ask the right questions to address those problems; gather pertinent data from many sources; efficiently, logically, and resourcefully sort through complex information; acknowledge personal biases that may hinder analysis; interpret data in the context of each patient before them; and expediently reach trustworthy conclusions that form the basis of therapeutic approaches (Tables 112-1 and 112-2).
| Critical Thinking Defined by Edward Glaser |
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In a seminal study on critical thinking and education in 1941, Edward Glaser defined critical thinking as follows: “The ability to think critically, as conceived in this volume, involves three things:
Critical thinking calls for a persistent effort to examine any belief or supposed form of knowledge in the light of the evidence that supports it and the further conclusions to which it tends. It also generally requires ability to recognize problems, to find workable means for meeting those problems, to gather and marshal pertinent information, to recognize unstated assumptions and values, to comprehend and use language with accuracy, clarity, and discrimination, to interpret data, to appraise evidence and evaluate arguments, to recognize the existence (or nonexistence) of logical relationships between propositions, to draw warranted conclusions and generalizations, to put to test the conclusions and generalizations at which one arrives, to reconstruct one’s patterns of beliefs on the basis of wider experience, and to render accurate judgments about specific things and qualities in everyday life.” |
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This chapter will draw upon a few cases to highlight basic concepts in critical thinking when ordering imaging studies. In the first case, overutilization of imaging studies subjected the patient to unnecessary risks of radiation and contrast and significantly prolonged length of hospital stay without altering management. In the second case, underutilization of imaging studies despite hospitalization resulted in diagnostic failure relating to a potentially life-threatening illness. In the third case, studies performed at the end of life were irrelevant to the patient’s futile care.
Asking the Right Questions
The hallmark of critical thinking requires asking the right questions to obtain the right information. Without the right information, we cannot make the correct diagnosis or order the correct treatment. A thorough history and physical examination will in fact usually lead to the correct diagnosis, especially in complex or perplexing cases. During emergency medical conditions, clinicians, however, tend to order tests first and clinical problem solve after the results are known, especially with imaging studies. With this approach clinicians will not find out information if they skip the step of asking pertinent questions.
The evidence-based medicine (EBM) approach requires a series of steps, the first of which is to ask a clinical question that can be answered. Failure to follow the first step will result in an unproductive search that cannot be applied to the patient in front of you (Table 112-3).
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Overutilization
ACUTE DYSPNEA AND CHEST PAIN A 59-year-old female with a past medical history of asthma and hypertension was admitted for surgery. The patient had no history of cardiac disease or pulmonary hypertension. A preoperative abdominal CT reported findings consistent with endometrial cancer. A preoperative CXR (PA and lateral) was normal. On postoperative day two, she developed chest tightness and shortness of breath. Her examination was notable for a blood pressure (BP) of 106/60 mm Hg, a pulse of 91 beats per minute (bpm), room air O2 saturation of 92%–95%, and a normal temperature of 97.9°F. Her physicians ordered chest physical therapy, furosemide, and nebulizer treatments, none of which relieved her symptoms. The patient subsequently developed severe 6–7 /10 chest pain. The patient underwent a chest CT-PE protocol read as showing no evidence of pulmonary embolism (PE) or deep venous thrombosis (DVT). The report noted bibasilar subsegmental atelectasis, a common finding after surgery, and evidence of aspiration pneumonitis of right lower lobe (RLL). It is possible that she aspirated during the scan which revealed food in her esophagus. This step did not occur and the patient continued to deteriorate. On postoperative day three at 10 pm she became anxious that “something is wrong.” Her dyspnea persisted, unchanged. Her vital signs revealed a BP of 100/60 mm Hg, heart rate 125 bpm, O2 saturation 82% on room air, increasing to 97% on 4L of supplemental oxygen, a temperature of 102°F. A cross-coverage note documented “flat” jugular venous pressure, coarse breath sounds, decreased at her lung bases, and decreased abdominal bowel sounds. Pertinent laboratory tests included a WBC 5,900/mm3 with 51% bands, BUN 35 mg/dL, creatinine 2.9 mg/dL (previously 0.8mg/dL), and normal cardiac enzymes. ECG revealed changes suggestive of right ventricular overload and bigeminy. Portable CXR reported low lung volumes, no edema, and small left effusion. Overnight she received two fluid boluses of 500 cc for systolic BP in the 70s, and her O2 requirement increased to 6L. Arterial blood gas reported pH 7.31, pCO2 52, p02 73 on face mask with 10 L supplemental O2. At 3 AM she complained of severe shortness of breath; her blood pressure was 60/30, her pulse 125 beats per minute, her temperature 99.1°F. On postoperative day five, the patient still complained of shortness of breath, pleuritic chest pain, and ongoing nausea. Her vital signs were notable for a BP of 90–130/50–70 mm Hg, a heart rate 96–116 bpm, and O2 saturation 97% (3L). Wheezing, diffuse rhonchi, and a tender right lower quadrant were now noted on physical examination. Abdominal CT with contrast Small bowel obstruction secondary to herniation between layers of anterior abdominal wall (Spigelian hernia) Chest CT (without contrast) New multifocal aspiration pneumonia with secretions or aspirated material in the right main stem bronchus. On postoperative day six, this patient underwent repair of an incarcerated hernia. There was no evidence of ischemic bowel. Her laboratory tests revealed a Cr 0.7 mg/dL and an elevated troponin 0.16. Although she felt less short of breath and described nasal and chest congestion similar to her allergies, she now was coughing up blood-tinged sputum. A monitor strip showing bigeminy and she was transferred to medicine under the care of another clinician with the presumptive diagnosis of submassive PE. Work-up on the medical service An ECG did not show signs of right heart strain (negative T waves in the precordial leads, a new RBBB, classic S1Q3T3, and Qr in lead V1), but a new Q in lead III was interpreted as consistent with an inferior myocardial infarction of indeterminate age. An echocardiogram did not confirm inferior segmental wall abnormalities, but reported moderately severe pulmonary hypertension and an enlarged right ventricle. Her troponin peaked at 0.44. The patient underwent an extensive evaluation for secondary causes of hypertension including additional imaging (Table 112-4). All studies were unrevealing and she was empirically discharged on warfarin. |
| Imaging | Comments |
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| Preadmission abdominal/pelvic CT: endometrial cancer | |
| Normal admission CXR(PA) and subsequent CXR (PA and lateral): atelectasis, low lung volumes, trace left effusion, retrocardiac density |
