Most legal texts state as a matter of law that in order to apply the doctrine of res ipsa loquitur it is required that plaintiff show that the instrumentality causing his injury was in the continuous and exclusive control of one defendant. This general proposition has been stated in Ohio on several occasions. However, in the last few years some exceptions to this general rule have been established in several jurisdictions.
Julien C. Renswick, Res Ipsa Loquitur in Hospital and Malpractice Cases, 9 Clev.-Marshall L. Rev. 199 (1960)