The inner voice

Laboratories and clinics that collect airflow data typically use either a standard pneumotachograph or the Rothenberg face mask. Because subjects and patients breathe through these masks and because these masks come into contact with skin, some procedure should be followed to prevent cross infection. Sterilization is not required since the masks do not normally come into contact with mucous membranes or the blood stream or other body fluids. However, simple procedures for disinfecting the masks should be followed to reduce or eliminate the risk of transmission of air-borne organisms and/or skin problems. Occasionally, saliva and/or sputum collect on the mask surfaces. These should be removed before the mask is disinfected. Rutala (1990) has described guidelines for infection control as adopted by the Association for Practitioners in Infection Control (APIC). Disinfection refers to procedures designed to eliminate many or all microorganisms with the exception of bacterial spores. There are three levels of disinfection. High level disinfection refers to items that come into contact with mucous membranes or nonintact skin. It is designed to destroy all microorganisms with the exception of bacterial spores in large concentrations. Intermediate level includes items such as bedpans, blood pressure cuffs, linens, utensils etc. At this level, vegetative bacteria, most viruses and fungi are eliminated but it does not kill bacterial spores. Low level items are those that come into contact with intact skin. Low level disinfection kills most bacteria, some viruses and some fungi. There are several potential chemical agents which can be used to disinfect smooth, hard-surfaced noncritical items, such as respiratory face masks. These agents include ethyl or isopropyl alcohol (at least 70%), sodium hypochlorite, iodophor germicidal solutions, or quaternary ammonium solutions. The latter three agents may be harmful to the cushion and/or wire mesh of the Rothenberg mask. Because they are potentially flammable, alcohols can be dangerous to use on a routine basis. Sodium hypochlorite is present in household bleach and although it should be handled with care, it can be an inexpensive and effective disinfectant. I t is also possible to use solutions designed for higher level disinfection such as glutaraldehyde, a solution commonly used to disinfect the laryngoscope. We use the Rothenberg face mask for the collection of airflow data, and the Smitheran and Hixon (1981) procedure for the estimation of lung pressure. In the latter procedure, a small-length tube is used to sense the pressure in the oral cavity. This tube is disposed of after use and does not need to be disinfected. It is possible to use household bleach as a disinfectant. The bactericidal component (5.25%) of bleach is sodium hypochlorite. The bleach should be diluted to produce a concentration of about 500-1000 ppm, or approximately a 25:1 ratio. According to Rutala, it is an effective bactericide, fungicide, tuberculocide, sporicide, and virucide. The solution will lose about 50% of its effectiveness after 30 days. Thus, a sufficiently strong solution should be prepared for it to be effective at 30 days. Since bleach is inexpensive, a proper concentration could be prepared weekly. Disposable gloves should be used when handling materials to be cleaned. First, the mask is washed in a solution of warm water and liquid detergent (Hibiclens, Stuart Pharmaceuticals). This is an important step to remove any material that may have been coughed or spat on the surfaces of the mask. The rubber cushion surrounding the mask is removed and both are immersed into a diluted bleach solution for 10 minutes. The mask and cushion are then rinsed thoroughly and allowed to dry. Bleach has a very strong odor that may be especially potent in the small mask space. However, the potency of the diluted solution should produce little residual odor. Occasionally, if another subject is waiting, the mask and cushion are dried with a common hair dryer. The diluted bleach solution appeared to have no harmful effects on the various components of the mask.