A serious reaction to a large amount of a drug that can result in death

You are a phlebotomist drawing a specimen from emma who says she doesn't like having blood drawn. in fact she tells you that the sight of blood makes her "queasy." you attempt to make her feel relaxed by quietly talking to her as you her onto a chair in the hospital laboratory. while you are drawing her blood sample, she faints and hits her head against the side of a cabinet. are you liable for emma's injury? why or why not?