https://bmcanesthesiol.biomedcentral.com/articles/10.1186/1471-2253-10-20
https://bmcanesthesiol.biomedcentral.com/articles/10.1186/1471-2253-10-22
https://bmcanesthesiol.biomedcentral.com/articles/10.1186/1471-2253-10-21
https://bmcanesthesiol.biomedcentral.com/articles/10.1186/1471-2253-10-23