A randomized, controlled, cross-over study in 21 healthy volunteers. The participants will receive a fluid bolus of 500 ml Ringer's Acetate at either 22°C or 38°C over 15 minutes in a randomized order. Non-invasive measures will be made of cardiac index, mean arterial pressure, systolic blood pressure, diastolic blood pressure, heart and pulse rate, saturation and temperature. Hemodynamic measure will be made using the Clearsight® system. Measurements will be made during 120 minutes. The second session will take place at least one day later, and the participant will then receive the other fluid temperature.