Usefulness of cellular analysis of bronchoalveolar lavage fluid for predicting the etiology of pneumonia in critically ill patients.
BACKGROUND
The usefulness of bronchoalveolar lavage (BAL) fluid cellular analysis in pneumonia has not been adequately evaluated. This study investigated the ability of cellular analysis of BAL fluid to differentially diagnose bacterial pneumonia from viral pneumonia in adult patients who are admitted to intensive care unit.


METHODS
BAL fluid cellular analysis was evaluated in 47 adult patients who underwent bronchoscopic BAL following less than 24 hours of antimicrobial agent exposure. The abilities of BAL fluid total white blood cell (WBC) counts and differential cell counts to differentiate between bacterial and viral pneumonia were evaluated using receiver operating characteristic (ROC) curve analysis.


RESULTS
Bacterial pneumonia (n=24) and viral pneumonia (n=23) were frequently associated with neutrophilic pleocytosis in BAL fluid. BAL fluid median total WBC count (2,815/µL vs. 300/µL, P<0.001) and percentage of neutrophils (80.5% vs. 54.0%, P=0.02) were significantly higher in the bacterial pneumonia group than in the viral pneumonia group. In ROC curve analysis, BAL fluid total WBC count showed the best discrimination, with an area under the curve of 0.855 (95% CI, 0.750-0.960). BAL fluid total WBC count ≥ 510/µL had a sensitivity of 83.3%, specificity of 78.3%, positive likelihood ratio (PLR) of 3.83, and negative likelihood ratio (NLR) of 0.21. When analyzed in combination with serum procalcitonin or C-reactive protein, sensitivity was 95.8%, specificity was 95.7%, PLR was 8.63, and NLR was 0.07. BAL fluid total WBC count ≥ 510/µL was an independent predictor of bacterial pneumonia with an adjusted odds ratio of 13.5 in multiple logistic regression analysis.


CONCLUSIONS
Cellular analysis of BAL fluid can aid early differential diagnosis of bacterial pneumonia from viral pneumonia in critically ill patients.
Department of Infectious diseases, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Republic of Korea.
Sang-Ho
SH
Choi
Department of Pulmonary and Critical Care Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Republic of Korea.
Sang-Bum
SB
Hong
Department of Infectious diseases, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Republic of Korea.
Hyo-Lim
HL
Hong
Department of Infectious diseases, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Republic of Korea.
Sung-Han
SH
Kim
Department of Pulmonary and Critical Care Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Republic of Korea.
Jin Won
JW
Huh
Department of Laboratory Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Republic of Korea.
Heungsup
H
Sung
Department of Infectious diseases, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Republic of Korea.
Sang-Oh
SO
Lee
Department of Laboratory Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Republic of Korea.
Mi-Na
MN
Kim
Department of Infectious diseases, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Republic of Korea; Asan Institute for Life Sciences, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Republic of Korea.
Jin-Yong
JY
Jeong
Department of Pulmonary and Critical Care Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Republic of Korea.
Chae-Man
CM
Lim
Department of Infectious diseases, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Republic of Korea.
Yang Soo
YS
Kim
Department of Infectious diseases, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Republic of Korea.
Jun Hee
JH
Woo
Department of Pulmonary and Critical Care Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Republic of Korea.
Younsuck
Y
Koh
D000328:Adult; D019540:Area Under Curve; D001992:Bronchoalveolar Lavage Fluid / Q000166:cytology / Q000382:microbiology*; D002097:C-Reactive Protein / Q000032:analysis; D002116:Calcitonin / Q000097:blood; D015740:Calcitonin Gene-Related Peptide; D016638:Critical Illness; D003937:Diagnosis, Differential; D006801:Humans; D007958:Leukocyte Count; D016013:Likelihood Functions; D016017:Odds Ratio; D018410:Pneumonia, Bacterial / Q000175:diagnosis* / Q000382:microbiology*; D011024:Pneumonia, Viral / Q000175:diagnosis*; D011498:Protein Precursors / Q000097:blood; D012372:ROC Curve; D012680:Sensitivity and Specificity
C000606589:CALCA protein, human; D011498:Protein Precursors; D002116:Calcitonin; D002097:C-Reactive Protein; D015740:Calcitonin Gene-Related Peptide