Haemodynamic effects of cold versus warm fluid bolus in healthy volunteers: A randomised crossover trial

Objective: To test the hypothesis that changes in cardiac index and mean arterial pressure (MAP) during and after a fluid bolus (FB) are altered by fluid temperature. Design: Randomised, controlled, crossover trial. Setting: Research laboratory at Swedish teaching hospital. Participants: Twenty-one healthy adult volunteers. Interventions: Subjects were randomly allocated to 500 mL of Ringer's acetate at room temperature (22 degrees C; cold) or body temperature (38 degrees C; warm). Main outcome measures: For 2 hours after starting the FB, we measured cardiac index, MAP, systolic blood pressure, diastolic blood pressure and pulse rate (PR) continuously. We recorded temperature and O2 saturation every 5 minutes during infusion and every 15 minutes thereafter. In a second session, volunteers crossed over. Results: During the first 15 minutes, mean cardiac index increased more with warm FB (0.09 L/min/m2 [95% CI, 0.06- 0.11] v 0.03 L/min/m2 [95% CI, 0.01-0.06]; P Trial registration: EudraCT no. 2016-002548-18 and Clinicaltrials.gov NCT03209271.