Gu. Meduri et al., CAUSES OF FEVER AND PULMONARY DENSITIES IN PATIENTS WITH CLINICAL MANIFESTATIONS OF VENTILATOR-ASSOCIATED PNEUMONIA, Chest, 106(1), 1994, pp. 221-235
Background: Ventilator-associated pneumonia, a leading cause of sepsis
in patients with acute respiratory failure, is difficult to distingui
sh clinically from other processes affecting patients receiving mechan
ical ventilation. We conducted a prospective study of patients with su
spected ventilator-associated pneumonia to identify the causes of feve
r and densities on chest radiographs and to evaluate the diagnostic yi
eld and efficiency of tests used alone and in combination. Methods: Th
e 50 patients entered into the study underwent a systematic diagnostic
protocol designed to identify all potential causes of fever and pulmo
nary densities. Diagnoses responsible for fever were established by st
rict diagnostic criteria for 45 of the 50 patients. The prevalence of
specific conditions and diagnostic yield of individual tests were used
to formulate a simplified diagnostic protocol. Results: The diagnosti
c protocol identified 78 causes of fever (median 2 per patient). Infec
tions were the leading causes of fever and pulmonary densities. Of the
45 patients with fever, 37 had one or more infections identified (67
sources). Most infections (84 percent) were one of four types: pneumon
ia, sinusitis, catheter-related infection, or urinary tract infection.
Ventilator-asseciated pneumonia occurred in only 42 percent. All but
nine infections (87 percent) were directly or indirectly related to in
sertion of a catheter or a tube. Concomitant infections were frequent
(62 percent), particularly in patients with sinusitis (100 percent), c
atheter-related infections (93 percent), and pneumonia (74 percent). O
f concomitant infections, 60 percent were caused by a different pathog
en. Noninfectious causes of fever were more common in the 22 patients
with adult respiratory distress syndrome. Histologically proved pulmon
ary fibroproliferation was the only cause of fever in 25 percent of pa
tients with adult respiratory distress syndrome. Radiographic densitie
s were caused by an infection in only 20 patients (19 pneumonia, 1 emp
yema). In more than 50 percent of the 25 patients without adult respir
atory distress syndrome, congestive heart failure, and atelectasis wer
e the sole causes of pulmonary densities, and fever always originated
from an extrapulmonary site of infection. Used in combination, broncho
scopy with protected sampling, computed tomographic scan of the sinuse
s, and cultures of maxillary sinus aspirate, central intravenous or ar
terial lines, urine, and blood identified 58 of the 78 sources of feve
r (74 percent). Conclusions: The observations in this study document t
he complex nature of acute respiratory failure and fever and underscor
e the need for accuracy in diagnosis. The frequent occurrence of multi
ple infectious and noninfectious processes justifies a systematic sear
ch for source of fever, using a comprehensive diagnostic protocol. A s
implified diagnostic protocol was devised based on the diagnostic valu
e of individual tests.