WhiteGAPS Evaluation


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An evaluation was conducted to ensure that WhiteGAPS are safe and effective barriers in guarding patient health by helping prevent cross-contamination through nitrous oxide hoods. 

An Evaluation of WhiteGAPS: A Barrier Device for Nitrous Oxide Hoods

Timothy S. Martin; J. Hadley Hall, DDS; Daniel K. Braunam, PhD; Abilene Christian University, Department of Microbiology, Abilene, TX Abilene Oral & Maxillofacial Surgery; Abilene TX.  Copyright © 2010

WhiteGAPS, a barrier device developed to prevent cross-contamination from repetitive use of nitrous oxide hoods, are disposable, non-dusting, non-irritating, spun-bonded polyester filters that cover the hood and are discarded after each use. WhiteGAPS (Gas Apparatus Protectors) are not intended as an alternative to disinfection but rather as a barrier to reduce microbial contamination of the hood and apparatus. In addition, they prevent facial oils and make-up from contaminating the hood.

Introduction: The use of barrier devices to control the spread of viruses, bacteria and other microbes is currently a primary concern in all medical fields, including dentistry. Though seldom used in the past, full-face coverage and surgical gloves have today become essential to protecting dentists from saliva, blood, air-borne particles, aerosols and other disease-carrying sources. Barrier devices for patients are also being developed. This product is designed to be used as a barrier between the patient and the nitrous oxide hood in order to keep the hood clean and reduce cross-contamination. A brief review of the problem will establish the urgency of this need. In 1952 an outbreak of tonsillitis was linked to inefficiently sanitized anesthetic apparatus (Joseph and Shay 1952). The same year, an editor in the British Medical Journal suggested that sterilization of face-pieces with antiseptic should be routinely carried out after each use. (Editorial, 1952). Cross-infection of patients by Pseudomonas aeruginosa was linked to contaminated anesthesia equipment (Olds, 1972; Tinne, 1967). Coughing or sneezing can generate aerosol mists that have been shown experimentally to always contaminate pre-sterilized anesthetic circuits (Jenkins, 1964; Thomas, 1972). Obviously, the mask, which is the first part of the anesthetic equipment to contact patients, offers the greatest source of cross-infection (Pandit, 1967). Contamination with sputum is especially dangerous because upon drying the survival of microorganisms is greatly enhanced (Thomas, 1972). Dried sputum and blood not only extend the life of viruses, but handling flexible materials upon which these dried body fluids are found produce bursts of dust-like particles that are rapidly disseminated, contaminating the entire room (Shovelton, 1982) and endangering both patient and dentist.

Procedure: This study was designed to determine the effectiveness of WhiteGAPS in reducing the transmission of bacteria from patient to the nitrous oxide hood. It was conducted in an oral surgeon’s office with patients undergoing extraction of their teeth. The average length of each procedure was approximately 30 minutes. Before each surgical procedure, the hood was disinfected with combination of phenol, sodium tetraborate, and phenate (Sporicidin® Spray, Dentsply International, Inc.), then thoroughly swabbed with sterile cotton swabs. The swabs were placed in 3 mL sterile phosphate buffered saline solution (pH 6). After the surgical procedure, the hood was again swabbed with a second sterile cotton swab and the swab placed in 3 mL sterile phosphate buffered saline. The patient’s nasal alae and periphery from the nares were swabbed and the swab placed in 4 mL sterile phosphate buffered saline. This procedure was performed on 30 patients with WhiteGAPS used in the nitrous oxide hood and 30 patients without WhiteGAPS used in the hood. Each patient thus had three samples taken for a total of 180 samples for 60 patients. The samples were shaken and 1 mL of each was pour-plated in mannitol salt agar (MSA) and an additional 1 mL of each was pour-plated in trypticase soy agar (TSA). Plates were incubated at 35°C for 48 hours, then removed, the colonies counted, and the data recorded.

Results: Significant protection (P<.02) from cross-contamination was provided by the use of WhiteGAPS. No bacterial growth was found on any plates of samples taken from the hoods after surgery in which WhiteGAPS were used. However, bacterial colonies were seen in post-surgical samples from 25 of 30 non-WhiteGAPS patients. Pre-surgical samples from control patients showed four cases of growth; the WhiteGAPS group showed eight cases. These were determined to be incidental growth and not due to insufficient disinfection procedures. Mannitol salt agar was used as a screen for Staphylococcus aureus, so lack of growth on this medium indicated an absence of S. aureus. but not necessarily an absence of other bacteria. TSA was used to show the presence of other types of bacteria in general.

Conclusion: We conclude, based on the finding that there was a zero-growth rate from samples taken when WhiteGAPS were used, that they are an effective barrier device. When used properly they will dramatically reduce the amount of bacteria that infect the nitrous oxide unit. Considering the extensive use of nitrous oxide units in dentistry as in other surgical outpatient facilities, and the role that the hood and circuitry of these units can play in the spread of disease, the importance of adding WhiteGAPS to the infection control regimen of the dental office is obvious.


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