Abstract
This study discusses how to estimate the size of operating department. In this paper (Part I), we analysed some indexes required to determine the number of operating rooms, using results of investigations in 23 hospitals. The followings are the important indexes. (1) The number of operations required per unit time (eg. per day). A strong correlation was observed between the number of operations and that of newly admitted in-patients. (2) The operating room capacity. That is the possible maximum number of operations per a room to be performed. The value of this index changes with the following factors. ・the operation length and the length of the hygenic interval (the time needed for operating room cleaning preparation of operation). ・the working length of the staffs (nurse/doctor) per day and the number of the staffs. (3) The number of the operating rooms being used in parallel. This index shows the activity of the operating rooms as (2). (4) The usage of operating room. The operating room is used commonly or specifically to clinical groups. In part II the authors intend to propose the method to determine the number of operating rooms that can solve the delay phenomena (queue) in a operation list.