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Chapter 14. Conduct and Interpretation of the Basic Chest Exam

A 67-year-old male presents to an acute care clinic complaining of 5 days of cough. He is a lifelong nonsmoker with no history of asthma, but worries that he has pneumonia. Physical exam reveals TB = 37.6°C, HR = 88 beats/min, f = 20 breaths/min, and systemic BP = 136/84 mm Hg. The trachea is midline. Chest exam findings are the following: the trachea is midline; there is a normal chest wall and symmetric chest expansion; there is symmetric fremitus and resonance to percussion throughout the lung fields; vesicular breath sounds are present throughout the lung fields; no wheezes, crackles, or rubs are heard. The pretest probability for pneumonia in patients presenting with the complaint of cough is ~5%. Using the scoring system of Heckerling and colleagues, what is the probability that this patient has pneumonia?

a. 3.5%

b. 2.1%

c. 1.3%

d. 0.8%

e. 0.2%

The most correct answer is b, 2.1%.

This patient's Heckerling score is 1 (see Community-Acquired Pneumonia in Adults earlier in the chapter). In this scoring system, a score of 0-1 has a +LR = 0.3. While students may think that this should be considered a –LR because it is < 1, the use of a multitiered scoring system dictates that all LRs are expressed as positive numbers. Using the nomogram in Fig. 14.4, the posttest probability is read as ~2.1%.

Figure 14.4

A standard nomogram of likelihood ratios (LR). The physician draws a straight line that begins with an estimated pretest probability of a patient diagnosis (left axis) through the LR ratio for the exam finding that is being conducted on the patient (center axis) to determine the posttest probability that the pretest diagnosis is correct. Adapted from Haynes RB, Sackett DL, et al: Clinical epidemiology: How to do clinical practice research, 3rd edition. Philadelphia, PA: Lippincott Williams & Wilkins, 2005.

A 27-year-old male presents to the emergency room after the sudden onset of right-sided chest pain 1 hour ago. His pain is accompanied by acute, but not severe, dyspnea. He has had no cough with this illness and is on no medications. The pain is described as sharp, and is worse with each chest excursion. He has never been hospitalized, never had surgery, and has no history of cancer, deep venous thrombosis, pulmonary embolus, or current leg pain. He has smoked one pack of cigarettes per day for 12 years. His vital signs are: TB = 37.0°C, HR = 96 beats/min, f = 28 breaths/min, ...

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