Risk Factors for Bloodstream Infection (BSI) in Patients With Severe Acute Respiratory Distress Syndrome (ARDS) Supported by Veno–Venous Extracorporeal Membrane Oxygenation (VV–ECMO)

Liuting Yang; Min Li; Sichao Gu; Yingying Feng; Xu Huang; Yi Zhang; Ye Tian; Xiaojing Wu; Qingyuan Zhan; Linna Huang


BMC Pulm Med. 2022;22(370) 

In This Article

Abstract and Introduction


Background: There were relatively few studies about the incidence and risk factors for bloodstream infection (BSI) in patients with severe acute respiratory distress syndrome (ARDS) supported by veno–venous extracorporeal membrane oxygenation (VV–ECMO).

Methods: Patients who were diagnosed with severe ARDS and received VV–ECMO treatment in the medical intensive care unit of China–Japan Friendship Hospital from August 2013 to March 2019 were retrospectively studied. The pathogens isolated from blood culture (BC) were identified and analyzed for drug sensitivity. The risk factors for BSI were analyzed by logistic regression.

Results: A total of 105 patients were included in this single–center retrospective cohort study. Among them, 23 patients (22%) had BSIs. 19 cases were identified as primary BSI; while the other 4 cases were as secondary BSI. A total of 23 pathogenic strains were isolated from BCs, including gram–negative (G) bacilli in 21 (91%) cases, gram–positive (G+) cocci in 1 case, fungus in 1 case, and multidrug–resistant (MDR) organisms in 8 cases. Compared with patients without BSI, patients with BSI had a higher Murray score (odds ratio = 6.29, P = 0.01) and more blood transfusion (odds ratio = 1.27, P = 0.03) during ECMO.

Conclusions: The incidence of BSI in patients with severe ARDS supported by VV–ECMO was 22%. G bacilli was the main pathogen, and most of them were MDR–G bacilli (MDR–GNB). Higher Murray score and more blood transfusion may be the independent risk factors for BSI.


Veno–venous extracorporeal membrane oxygenation (VV–ECMO) is the gold standard of support in the treatment of severe refractory acute respiratory distress syndrome (ARDS). Although equipment technology has greatly improved, the incidence of complications, especially infection, remains high and might affect the clinical outcomes of patients.

According to two retrospective analyses of Extracorporeal Life Support Organization (ELSO) data by Vogel and Bizzarro, the prevalence of hospital–acquired infections in adult patients during ECMO was 21%,[1] while the incidence of BSI during ECMO ranged from 3 to 18%.[2–5] Compared with that in patients supported by veno–arterial ECMO (VA–ECMO), the infection rate in patients supported by VV–ECMO was higher.[6] The reasons might be attributed to longer treatment times and more frequent exposure to antibiotics and systemic steroids during VV–ECMO.

The pathogens and risk factors for BSI vary among different patients and different modes of ECMO. Enterobacteriaceae was reported to be the most common pathogen of BSIs, accounting for 16%, and the incidence of BSI caused by Enterobacteriaceae was 4.45 cases/1000 ECMO days.[2] Renal failure[7] and blood transfusion due to anemia and thrombocytopenia were identified as risk factors for BSI in patients with cancer.[8] A study in 92 patients with VA–ECMO indicated that age and serum total bilirubin level pre–ECMO were risk factors.[9] A single–center retrospective cohort study noted that patients with BSI during VV–ECMO had a longer duration of ECMO support than patients without BSI (18 days vs. 9 days, P < 0.01).[10] The effect of BSI on mortality in ECMO patients remains controversial. A retrospective cohort study by Steiner et al. observed a threefold increase in the risk of death in patients suffering from BSI during ECMO.[11] However, other studies revealed that although BSI increased the length of hospitalization, there was no effect on hospital mortality.[1–4]

Relevant data of patients with severe pneumonia–induced ARDS who are supported by VV–ECMO are extremely limited. We therefore conducted a study to evaluate the incidence and risk factors for BSI in severe ARDS patients supported by VV–ECMO.