In 1968 E.H. Spaulding classified medical devices into three categories, namely, highly hazardous items, moderately hazardous items and low hazardous items, based on the magnitude of the risk of infection resulting from the use of the medical device after contamination and the requirements for disinfection or sterilization between patient uses.

1、Highly dangerous items
Items that enter the sterile tissues and organs of the human body, the vascular system, or have sterile body fluids flowing through them or items that come into contact with broken skin or broken mucous membranes have a very high risk of infection once they are contaminated by microorganisms, such as surgical instruments, puncture needles, laparoscopes, biopsy forceps, cardiac catheters, implants, and so on.

2、Medium-dangerous items
Items that come into contact with intact mucous membranes without entering the sterile tissues, organs and blood stream of the human body or contacting broken skin or broken mucous membranes, such as gastrointestinal endoscopes, tracheoscopes, laryngoscopes, anal tables, oral tables, ventilator tubes, anesthesia machine tubes, tongue depressors, anorectal pressure-measurement catheters, and so on.

3、Low-dangerous items
With intact skin contact Li not in contact with mucous membranes of the device. Such as stethoscopes, sphygmomanometer cuffs, etc.; beds with rails, bed surface and bedside tables, bedding; walls, floors; spittoons (cups) and commodes.