[1] Univ Lubeck, Dept Neurosurg, Ratzeburger Allee 160, D-23538 Lubeck, Germany
[2] Herz Jesu Krankenhaus Munster Hiltrup, Dept Anesthesiol, Munster, Germany
[3] Klinikum Weser Egge, Dept Anesthesiol, Hoxter, Germany
[4] Klinikum Bremen Mitte, Dept Pediat, Bremen, Germany
[5] Klinikum Osnabruck, Dept Gynecol & Obstet, Osnabruck, Germany