Antimicrobial Therapy for Pneumonia or Fluid Overload?

Abstract

Patients with evidence of fluid overload or heart failure (HF) without clinical symptoms of pneumonia are often treated with antimicrobial therapy for pneumonia. We conducted a retrospective study to evaluate the use of antimicrobial therapy in critically ill patients with fluid overload or heart failure diagnosed as pneumonia. A retrospective chart review of patients on antimicrobial therapy treated for pneumonia in the intensive care unit was conducted. The study's primary outcome was the number of cases with no evidence of pneumonia, including fluid overload or heart failure, managed with antimicrobial therapy for pneumonia. Patients on antimicrobial therapy for other infections were excluded. Appropriateness of antimicrobial therapy was based on radiographic evidence, clinical data, and presentation. Patient group categories were A (pneumonia) and B (no evidence of pneumonia, fluid overload, and heart failure). Based on the subdivision of patients in Group B, where there was no evidence of pneumonia, we further classified it into two subgroups: heart failure (HF)/fluid overload (Group B1) and no evidence of HF or fluid overload (Group B2). Patients with evidence of pneumonia (Group A) were compared to the group with fluid overload and heart failure (Group B1). A p-value of < 0.05% was considered significant for detecting statistical difference. Post-screening, data on 56 patients were collected for the study and analyzed. Mean body temperature and white blood cell count were 37.6 + 0.6 o C, and 17.4 + 6.88 x10 3 µL, respectively. Based on radiographic evidence, clinical data, and presentation, 29 (52%) were classified under Group A, while 27 (48%) were classified under Group B. Median brain natriuretic peptide (BNP) for Group A vs. Group B was 514 (IQR: 1077) vs. 758 (2212) pg/mL p=0.14. The median duration of inpatient antimicrobial therapy was 7 (interquartile range [IQR]: 6) vs. 6 (IQR: 4) days, p=0.52, while the median duration of the total (inpatient and discharge prescription) antimicrobial therapy was 11 (IQR: 6) vs. 11 (IQR: 5), p=0.21. Patients with evidence of pneumonia (Group A) were compared to the group with fluid overload and heart failure (Group B1). The median BNP for the two groups was 514 (IQR: 1077) vs. 1040 (2094) pg/mL, p=0.04. Patients with documented echocardiographic evidence of ejection fraction < 55% were 4 vs. 14 for Groups A and B1, respectively. Additionally, the median BNP for Group A vs. Group B2 was 514 (IQR: 1077) vs. 189 (418) pg/mL, p=0.02. These findings demonstrate a 48% inappropriate use of antimicrobial therapy in patients with congestive heart failure (CHF), or fluid congestion misdiagnosed as pneumonia. There was a significant difference in the median BNP observed in patients with pneumonia compared to those with fluid overload and heart failure treated as pneumonia. More cases of patients with elevated BNP and reduced left ventricular ejection fraction (LVEF) were observed in patients with fluid overload or CHF treated as pneumonia than those diagnosed with pneumonia alone. Appropriate interpretation of radiographic evidence, laboratory data, and critical clinical assessment for the use of empiric antimicrobial therapy in this population is warranted.