used less frequently. Its role is generally reserved for institutions that do
not have access to spiral CT angiography and for individuals with a con-
traindication to spiral CT angiography (eg, contrast dye allergy, pregnancy).
An upright abdominal x-ray (d)can assess for abdominal perforation, char-
acteristically revealing air under the diaphragm.
50.The answer is b.(Rosen, pp 986-88.)Most pneumonia is the result of
a single species of bacteria. Streptococcus pneumoniaeis the most common
cause of community-acquired pneumonia. It is also the most common
cause of bacterial pneumonia in HIV-infected patients. Patients may appear
ill and exhibit tachypnea. Fever and chills are usually present. Auscultation
of the lungs reveals decreased breath sounds over the infiltrate and the
radiograph shows a lobar pattern.
(a)Haemophilus influenzaeis the second most common cause of
community-acquired pneumonia in adults and is particularly common
among patients with COPD and AIDS. (c)Klebsiella pneumoniaecommonly
occurs in alcoholics, diabetics, and COPD patients. Radiograph findings
include a necrotizing right-upper lobe infiltrate or abscess with an air-fluid
level. Although the patient in the scenario is an alcoholic, S pneumoniaeis still
the most common cause of community-acquired pneumonia. (d)Group A
streptococci is a rare cause of pneumonia that is associated with a high mor-
tality as a result of a rapidly progressive pneumonitis. (e)Pseudomonaspneu-
monia is usually only seen in the ICU with ventilated patients.
51.The answer is d.(Rosen, pp 172-178.)In the history there are details
that lead you to suspect pulmonary embolus: obesity, recent travel, pro-
gressive dyspnea despite inhaler treatment, and blood-streaked sputum.
Objectively, her ECG shows right heart strain (large R waves and inverted
T waves in the precordial leads V 1 –V 3 ), which is because of the heart beat-
ing against the high resistance of the pulmonary vasculature causing back-
flow resulting in right ventricular enlargement. She is tachycardic, tachypneic,
and hypoxic, cardinal signs of cardiovascular distress. Either dyspnea, pleu-
ritic chest pain, or tachypnea is present in 95% of patients with a PE. The clas-
sic triad of dyspnea, pleuritic chest pain, and hemoptysis is uncommon and
present in less than 25% of patients.
(a)Mycoplasma pneumoniaeis the most common cause of atypical “walk-
ing” pneumonia. Most patients have constitutional symptoms, in addition to
conjunctivitis, pharyngitis, or bullous myringitis. The hallmark of the disease
is the disparity between the patient’s clinically benign appearance and the
Shortness of Breath Answers 65