Fluid boluses are often administered with the aim of improving tissue perfusion in critically ill patients. It is unclear whether the temperature of the fluid has an impact on the hemodynamic response. The aim of this study is to describe the hemodynamic effects of a fluid bolus with two different temperatures.

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.

Inclusion Criteria:

- Volunteers 18 years or older Previously healthy

Exclusion Criteria:

• American Society of Anesthesiologists classification 2 or above.
• Known pregnancy

Unblinded (unable to blind subjects)