Received: 19 March 2020
Accepted: 18 May 2020
First Online: 27 May 2020
Ethics approval and consent to participate
: This retrospective study was approved by the Institutional Review Board of the University Hospital of Tuebingen and the requirement for informed consent was waived.
: Not applicable due to retrospective character of the study with full anonymization and waiver of informed consent by the local IRB.
: The authors declare that they have no competing interests.