The Facts About Tympanic Thermometers And Cross Contamination
Linda DiBenedetto, R.N.
Senior Clinical Study Associate
Review of the medical literature and consultation with epidemiology experts show that inanimate objects, such as the IVAC CORE.CHECKT tympanic thermometer, have minimal risk of being the mode of transmission for infectious organisms. There has been controversy for years about the contribution of objects and equipment used in the hospital environment to the risk of transmission of potentially infectious rganisms to patients1. Rhame2 summarized information known about the role of the inanimate environment in potential transmission and concluded that most outbreaks of nosocomial infection are associated with person-to-person spread or due to contamination of an item that should be sterile. These outbreaks, however, are rare and unusual events.
The infectious disease process (chain of infection) is depicted in many references3 as having six steps or links:
- Causative Organism (usually bacterial, viral, or fungal)
- Reservoir where organisms survive but may or may not multiply (includes persons and inanimate objects)
- Portal of Exit where organisms leave the reservoir (includes respiratory, gastrointestinal and genitourinary systems, the skin/mucous membranes, transplacentally and blood)
- Mode of Transmission for transfer of the organism from a reservoir to a susceptible host (directly, e.g., transmission of organisms to an open cut on the skin; indirectly, e.g., transmission of organisms from one patient to another via the hands of the care provider; and airborne, e.g., pulmonary tuberculosis)
- Portal of Entry or path for the organism to enter the susceptible host (includes respiratory, gastrointestinal and genitourinary systems, the skin/mucous membranes. transplacentally and blood via percutaneous contact)
- Susceptible Host or person lacking resistance to a particular infectious agent
Breaking the chain at any link will prevent transmission of organisms from the reservoir to a susceptible host. This information can be applied to planning intervention strategies to reduce risks of transmission of organisms in tympanic thermometry. The use of disposable probe covers and appropriate handwashing by the care providers are effective ways to minimize cross-transmission. Although cross-transmission by hands is possible, it is not very likely and has an extremely low risk when the only contact is with intact skin.
In 1985, the Centers for Disease Control (CDC) published a revised version of the "Guideline for Handwashing and Hospital Environmental Control"4. If the same care provider is only taking vital signs using a tympanic thermometer on a series of patients and is providing no other care activities at the time, the care provider has contact with intact skin only and does not put him/herself at risk for being contaminated with organisms that would put other patients at risk via cross-transmission; then, handwashing between patients would not be indicated.
The risks of transmitting organisms from one patient to another patient via a tympanic thermometer are extremely low because the ear canal and tympanic membrane are lined with skin tissue (no mucous membranes), and the probe cover is a single use item. Contact with the health care worker's hand for removal of the probe cover is no different than the health care worker's hand contact with intact skin similar to taking non-invasive blood pressure measurements. To reduce the risks of cross-contamination even further, before using the CORE.CHECK tympanic thermometer, the care provider should evaluate the condition of the patient's ear and adjacent skin. The thermometer should not be used on patients with ear drainage, infected or excoriated skin adjacent to the ear, or incisions adjacent to the ear. When used correctly, the CORE.CHECK tympanic thermometer does not present an infection risk nor a cross contamination risk to patients and it insures an accurate core temperature measurement in a minimum of time.
REFERENCES
- 1. Maki DG, Alvarado CS, Hassemer CA, Zilz MA: Relation of the inanimate hospital environment to endemic nosocomial infection, New Engl J Med 1982; 307:1562-1566.
- 2. Rhame FS: Chapter 14: The inanimate environment. In: Bennett JV, Brachman PS (editors): Hospital Infections, 2nd edition. Boston: Little Brown & Co., 1986:223-249.
- 3. Soule BM (editor): The APIC Curriculum for Infection Conytol Practicem Volume 1. Dubuque, lowa: Kendall-Hunt Publishing, Co., 1983:26-33.
- 4. Centers for Disease Control: Guideline for handwashing and hospital environmental control, 1985. In: Guide for the Prevention and Control of Nosocomial Infections, 1981-1985 (revised periodically). Atlanta: CDC.
July 1991
