We discuss the formulation of a prescription for intravenous (i.v.) fluid therapy (a ‘volume prescription’) for critically ill patients: pros/cons of different fluid types; accurate dosing; and qualitative and quantitative toxicities. Updated physiologic concepts are invoked and results of recent major clinical trials on i.v. fluid therapy in the acutely ill are interpreted.
Context is vital and any fluid can be harmful if dosed incorrectly. When contrasting ‘crystalloid versus colloid’, differences in efficacy are modest, but differences in safety are significant. Differences in chloride load and strong ion difference appear to be clinically important. Quantitative toxicity is mitigated when dosing is based on dynamic parameters that predict volume responsiveness. Qualitative toxicity for colloids (even with newer hydroxyethyl starch 130/0.4 solutions) and isotonic saline remain a concern.
Similar to any drug used in acutely ill patients, clinicians ordering a volume prescription must recognize that context is crucial. Physiologically balanced crystalloids may be the ‘default’ fluid for acutely ill patients, and the role for colloids is unclear. Optimal dosing involves assessment of volume responsiveness.
aDepartment of Anesthesiology
bDepartment of Critical Care Medicine, Duke University Medical Center/Durham VAMC, Durham, North Carolina, USA
cDivision of Critical Care Medicine, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
Correspondence to Dr Sean M. Bagshaw, Division of Critical Care Medicine, University of Alberta Hospital, 3C1.16 Walter C. Mackenzie Centre, 8440-122 Street, Edmonton, Alberta T6G2B7, Canada. Tel: +1 780 407 6755; fax: +1 780 407 1228; e-mail: email@example.com