Intravenous fluid use after cardiac surgery: a multicentre, prospective, observational study.

Background: The optimal strategy for fluid replacement after major surgery remains unclear and there is considerable interest in the investigation of more restrictive fluid regimens.

Objective: We aimed to establish current practice of fluid administration to patients after cardiac surgery.

Design, Setting And Participants: A multicentre, prospective observational study, over an 8-week period, of consecutive patients admitted to five intensive care units in New Zealand and Australia.

Main Outcome Measures: We collected patient demographic data and details of fluid boluses and all other intravenous (IV) fluids administered in the first 24 hours after ICU admission.

Results: We included 235 patients, and 1226 fluid boluses with an average volume of 504 mL/bolus were administered. The median total fluid given for volume expansion in the first 24 hours was 2250mL (interquartile range [IQR], 1250-3500mL) from a median total IV fluid intake of 4493mL/patient (IQR, 2842-5498 mL). The decision to administer a fluid bolus was made 40% of the time by nursing staff, 45% by an ICU resident and 12% by an ICU specialist. The most common reason for fluid administration was hypotension (65%), and crystalloid fluid was used for 65% of the boluses.

Conclusions: We showed that fluid boluses are responsible for a large proportion of the positive fluid balance seen in patients after cardiac surgery. These data justify further study to evaluate whether modification of fluid bolus administration can improve patient outcomes.