Association of Positive Fluid Balance and Mortality in Sepsis and Septic Shock in An Australian Cohort

In patients with septic shock, a correlation between positive fluid balance and worsened outcomes has been reported in multiple observational studies worldwide. No published data exists in an Australasian cohort. We set out to explore this association in our institution. We conducted a retrospective audit of patient records from August 2012 to May 2015 in a single-centre, 24-bed surgical and medical intensive care unit (ICU) in Sydney, Australia. All patients with septic shock were included. Exclusion criteria included length of stay less than 24 hours or vasopressors needed for less than six hours. Data was gathered on fluid balance for the first seven days of ICU admission, biochemical data and other clinical indices. The primary outcome measure was survival to hospital discharge. One hundred and eighty-six patients with septic shock were included, with an overall hospital mortality of 23.7%. Seventy-five percent of patients required mechanical ventilation, and 27.4% required haemodialysis. The mean daily fluid balance on the first day of admission was positive 1,424 ml and 1,394 ml for ICU and hospital survivors, respectively. On average, the daily fluid balance for non-survivors was higher than the survivors: ICU non-survivors were 602 (95% confidence intervals 230, 974) ml (P=0.0015) and hospital non-survivors were 530 [95% confidence intervals 197, 863] ml (P=0.0017) higher than the survivors. In line with other recently published data, after adjustment for confounders (severity of illness based on the Acute Physiology and Chronic Health Evaluation score) we found a correlation between positive fluid balance and worsened hospital mortality in critically ill patients with sepsis and septic shock. Further research investigating rational use of fluids in this patient group is needed.