- Correspondence to Dr Amund Hovengen Ringen, Department of Anesthesia, Oslo University Hospital Ulleval, Oslo 0424, Norway;
- Received November 23, 2018
- Revised February 14, 2019
- Accepted February 28, 2019
- First published April 25, 2019.
If you wish to reuse any or all of this article please use the link below which will take you to the Copyright Clearance Center’s RightsLink service. You will be able to get a quick price and instant permission to reuse the content in many different ways.