Published on 07/02/2015 by admin
Filed under Anesthesiology
Last modified 07/02/2015
This article have been viewed 1060 times
Beth A. Elliott, MD
Equipment and materials containing natural rubber latex (NRL) were once ubiquitous in the modern health care environment. Following the recommendation by the Centers for Disease Control and Prevention for universal precautions in 1987, the use of latex gloves increased dramatically (from 800 million to 20 billion annually). Subsequently, in the 1990s, NRL emerged as a significant cause of allergic reactions in both patients and health care workers. It remains unclear whether this escalation in reactions was the result of increased NRL glove use or abnormally high levels of residual latex antigens in the gloves. Manufacturers, hospitals, and clinics have taken steps to replace NRL with nonallergenic materials wherever possible. However, NRL gloves continue to be used in many operating suites due to their superior tactile properties and fit and a desire for reliable protection against blood-borne pathogens.
Latex is derived from the milky sap of the rubber tree, Hevea brasiliensis, harvested primarily in Malaysia, Indonesia, and Thailand. Approximately 90% of latex is used in the production of “dry” rubber for tires; the remaining 10% is used in the manufacture of “dipped” products, such as gloves, condoms, and balloons. During the manufacturing process, a variety of chemicals are added (e.g., stabilizers, antioxidants, accelerators) to give the rubber the desired characteristics. Once formed, the rubber products are then vulcanized (i.e., cured with heat and sulfur at a temperature of 130°C for 5 to 30 min). For latex gloves, a series of leaching baths are used to rid the gloves of residual water-soluble proteins and excess additives.
Antigenic proteins constitute up to 3% of the final latex product. Antigen levels are typically much higher in dipped latex products than in dry ones, but the levels can vary as much as 1000-fold among lots of gloves by the same manufacturer and as much as 3000-fold among manufacturers. These latex proteins (allergens) are water soluble and can be eluted during contact with moist surfaces (mucous membranes, peritoneal surfaces, and normal skin moisture). Latex allergens also adsorb onto the powder inside gloves. When gloves are donned or discarded, these powders disperse into the air and are inhaled by people nearby.
Irritant contact dermatitis produces a dry scaly irritation of the skin, typically on the hands. This problem is the most common work-related reaction to rubber products (80%). The reaction results from direct irritation by latex and residual chemicals used in the manufacturing process and is exacerbated by frequent handwashing and use of irritant surgical soaps. This reaction is not immune mediated and can be prevented with simple barrier protection or use of a nonlatex alternative.
Allergic contact dermatitis is another common problem associated with exposure to latex products. A red vesicular rash typically appears within 6 to 72 h after contact. The reaction is a type IV cell-mediated immune response to low-molecular-weight accelerators and antioxidants in the rubber product. Antibodies are not involved in type IV reactions. The diagnosis is based on clinical history and on the morphology and distribution of skin lesions. Patch testing confirms the diagnosis. Use of a glove liner or nonlatex alternative should be preventive.
The first case of type I IgE-mediated immediate hypersensitivity reaction to latex was reported in the German literature in 1927. The second case was not reported until 1979. By the 1990s, type I allergy to NRL reached epidemic proportions, with numerous reports of anaphylaxis and death.
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