(Type I IgE Mediated Hypersensitivity)
(Urticaria, Rhinitis, Asthma, and Anaphylaxis)
Although the timing of severe reactions to allergens like bee sting allergy are clear, it is often unclear which product will cause or when a patient actually contacts latex in the environment will develop anaphylaxis. Over 40,000 consumer products may contain latex and potentially serve as sources of water soluble allergenic proteins. Contact with skin, mucous membranes (like common dental procedures), or airway may induce a variety of allergic reactions. Latex is ubiquitous and it may become impossible for the clinician to implicate a specific device. Thus the care of individuals sensitized to latex is increasingly difficult but must include personal changes in latex use as well as changes at home, school, and work to successfully reduce complications.
The highest risk groups to develop latex allergy are individuals who are atopic and those who are frequently exposed to latex. Studies show that about 9% of these groups have latex specific IgE (skin test evidence for latex allergy). For those people who are both atopic and frequently exposed to latex, about 1/3 of them have skin test evidence for latex allergy. There had been no extensive studies, however, showing how many of those who are sensitized actually develop clinical allergy (urticaria, rhinitis, asthma, or anaphylaxis). It is clear that children with spina bifida who are sensitized to latex have a high chance of developing intraoperative anaphylaxis secondary to latex. According to some investigators in the field, it is their experience that health care workers appear to have a progression of occupational symptoms, from cutaneous reactions, to rhinoconjunctivitis, to bronchospasm and anaphylaxis. In addition, the presence of latex-specific IgE may precede the development of clinical symptoms by months or years. It seems prudent to identify these latex allergic individuals, and to recommend a latex safe environment, especially during surgical or dental procedures.
Diagnostic work-up for patients suspected to be allergic to latex includes careful history and physical examination, keeping the risk groups in mind. The patients should be asked about history of latex associated reactions like contact urticaria upon wearing latex gloves; rhinitis, conjunctivitis, asthma, and/or anaphylaxis while at work, improved while on vacation, can also be clues to possible latex Type I hypersensitivity. Latex allergy should also be in the differential diagnosis in a patient experiencing anaphylaxis during operation or routine dental procedures. Clinical testing to confirm the diagnosis includes skin testing, RAST, workshift spirometry, and/or methacholine challenge.
The first treatment goal is prevention. Primary prevention is to prevent sensitization. Using latex gloves with the lowest allergen content may be helpful to decrease the chance of sensitization. Enclosed are published data regarding the allergen content in different brands of latex gloves used during 1993. Once an individual becomes sensitized, he or she has to avoid latex completely. He or she should use non-latex type gloves (see partial list enclosed). Co-workers should use non-powdered latex gloves because it is well known that the latex allergen can become airborne after it is bound to the powder. Health care workers are often concerned about the barrier effectiveness of nonlatex gloves. Since 1991, the FDA has imposed identical quality control standards on all medical gloves regardless of manufacture material. Furthermore, the barrier effectiveness of latex gloves is highly variable. Regardless of the barrier materials used, health care personnel should be reminded of the primary importance of intact skin and frequent handwashing in the prevention of the transmission of viral disease. Using latex gloves by latex allergic workers (with the fear of the ineffectiveness of non-latex gloves) does not make sense because not only they are at risk in developing severe allergic reaction, the allergic reaction on their skin may affect their most important barrier: an intact skin.
When latex allergic health care worker becomes a patient, stringent latex avoidance is necessary because of high chance of exposure via mucosal and parenteral routes. Identification of medical equipment that may contain latex will be important. Since there is no uniform device labeling process or consumer product labeling for content, it becomes very difficult to identify all of the products that contain latex. One method of identifying the products that contain latex may be an approach through letter writing to the manufacturer requesting their support in identifying whether their products contain latex or not. An example of successful form letter adopted from the Children Hospital of Wisconsin is included in this handout.
Not all latex products can be substituted. Many of the syringe plungers contain latex but there is little evidence that this is a source of soluble protein. Glass syringes appear to be relatively impractical and using disposable syringes without allowing the medication to incubate in them for prolonged periods of time seems to be reasonable when a non-latex containing plunger is unavailable. Many medication vial tops of injectable medications are made out of latex. Puncturing these tops may disrupt protein into the fluid to be administered and may cause a severe anaphylactic reaction. Removing the top in order to withdraw the medication directly may be necessary.
Routine use of premedication prior to an operation may not be effective enough in preventing IgE mediated anaphylaxis. Some preliminary data suggest that the use of corticosteroid, antihistamine, and ephedrine may lessen the severity of reactions. Nevertheless, avoiding latex is important during surgical and dental procedures, along with premedication to prevent accidental latex exposure. Use of immunotherapy at this point in time has not been shown to be effective. The disease may be amenable to immunotherapy in the future when we define more specifically the proteins involved with latex allergy. At that time, we may also be able to eliminate this allergen in the latex manufacturing process.