https://bmcanesthesiol.biomedcentral.com/articles/10.1186/1471-2253-11-2
https://bmcanesthesiol.biomedcentral.com/articles/10.1186/1471-2253-11-4
https://bmcanesthesiol.biomedcentral.com/articles/10.1186/1471-2253-11-3
https://bmcanesthesiol.biomedcentral.com/articles/10.1186/1471-2253-11-5