Hemodynamic parameters will be measured in supine position. Volunteers will be turned into prone position. After a five-minute stabilization phase will be monitored CI, MAP, heart rate (HR), stroke volume variation SVV, systemic vascular resistance index (SVRI) by non-invasive measurements using a ClearSight (Edwards) in two prone positions (lying on support system allowing a free abdomen and then lying flat without any device). Furthermore, the width of the inferior vena cava and vena jugularis interna, vena saphena and vena cephalica will be measured by ultrasound. The measurement will be performed in inspiration and in expiration phase.

Unsupported prone position with arms along the body in neutral position will be used first without any supportive device except support of heels with a soft cylindrical device, head will be held in a neutral position using prone head rest. After recording of all measered values, the prone position using the prone position support system will be tested. The support system allows free movement of the lower thorax and abdomenal wall, upper arms are elevated and angled in 90 degrees (in shoulders and elbows). Heels will be positioned at the level of the heart using a supportive cylindrical device. Head will be held in a neutral position using prone head rest.

after changing supine to prone position

after changing supine to prone position

after changing supine to prone position