https://bmcanesthesiol.biomedcentral.com/articles/10.1186/1471-2253-12-4
https://bmcanesthesiol.biomedcentral.com/articles/10.1186/1471-2253-12-6
https://bmcanesthesiol.biomedcentral.com/articles/10.1186/1471-2253-12-3
https://bmcanesthesiol.biomedcentral.com/articles/10.1186/1471-2253-12-5