Lifesaving latex--a cautionary tale
By Jim Barrett
As a boy, Keith Chapman remembers his lips tingling when he would blow up a balloon. He was at a birthday party the first time, having fun, and the feeling passed quickly.
He didn't know the warning was serious.
In February, he slipped into anaphylactic shock, a life-threatening condition, when a latex dental dam chafed his lips. Chapman, a Health Science Center dental student, was practicing clinical procedures along with other second-year students. He was taken for emergency treatment and hospitalized overnight for observation.
"My lip was swollen. I broke out in a rash. I have asthma, and I began to breathe heavily," Chapman said. His physician later diagnosed him as allergic to latex.
"We are all more aware of latex allergy because of what happened to me. We discuss subjects such as allergies as part of our instruction, but when it actually happens, everyone pays more attention to the possibility that they or their patient may have allergies," he said.
The number of reported latex allergy cases has been growing for nearly 10 years, and the rise almost coincides with the 1987 federal order requiring gloving and other clinical precautions against the HIV virus. Since then, the use of latex gloves has soared. Before universal precautions, the nation used an estimated 300 million gloves a year. Now the figure has reached 9.6 billion gloves a year.
Latex allergy affects about 1 percent of the general public, but certain people run higher risks than others. Health care workers and patients with spina bifida, a spinal cord disorder, seem to be most vulnerable.
Estimates vary, and there are disputes among medical professionals, but those with spina bifida have a 34-64 percent risk of having an allergic reaction, and health care workers run a 3-8 percent risk. Physicians have a 10 percent risk factor, and the risk is even higher, perhaps 20 percent, among those who are atopic, or prone to allergies.
How accurate the estimates are is up for debate. Many cases are reported by the patient and unverified by a blood test. But no one denies that the number of cases is rising.
Latex first came under suspicion as an allergen in 1989. The U.S. Food and Drug Administration (FDA) received reports of patients lapsing into anaphylactic shock as they prepared to receive barium enemas. About 8 million to 10 million barium enemas are performed a year in the United States, and most without medical complications. But in a period of only a few months, the FDA received reports of 150 patients with allergic reactions, some severe. Nine deaths were reported.
Allergists first suspected barium, but several victims had reactions before they received barium. The cause was traced to a latex enema tip. The New York manufacturer voluntarily recalled the product, and the FDA issued a bulletin asking physicians to report allergic reactions to latex products.
No new latex deaths have been reported since to the FDA. But the federal agency this year proposed mandatory labeling of latex products used in clinical settings. Many manufacturers already label medical and dental products on a voluntary basis.
Latex comes from the milky sap of the commercial rubber tree, Hevea Brasiliensis, and it is the main component of natural rubber. Latex contains hundreds of proteins, including enzymes that are involved in the biosynthesis of the rubber molecules. Additional chemicals, such as accelerators and antioxidants, are added for strength, stretch and durability. Gloves and other medical and dental appliances with latex components have proven for years to be strong, flexible and reliable.
Since latex is so useful in dentistry and medicine and is so widely used, schools such as the Health Science Center and hospitals such as University Hospital in San Antonio, one of its major teaching centers, have searched for ways to minimize the allergy risk without scrapping all use of latex.
Students and clinical personnel in the Dental School, for example, are evaluating alternative gloves and other products that use no latex. And student volunteers are part of a study designed to measure their tolerance of latex allergens. Antibodies in the blood from entering freshmen and graduating seniors will be compared in the coming months to look for clues about latex allergy.
The researchers theorize that the graduating seniors will have a higher incidence of antibodies to latex compared to incoming students because of more extensive exposure to latex. In the medical setting, latex-free products are held on standby in the operating rooms at University Hospital. Hospitals have hundreds of latex products, ranging from gloves to catheters.
Both the Dental School and the hospital also are using latex gloves, but ones that do not contain powder on the inside. The powder spreads the latex allergen into the air, and affects people who breathe it. Powder makes putting on and removing the gloves easier, and it also helps speed manufacturing of gloves. Sterile latex gloves with powder cost about $16 for a box of 100; powder-free, sterile, non-latex gloves cost about $82 a box. "In a time when health care costs are under pressure and scrutiny, any widespread protocol changes that would increase costs must be carefully evaluated and subjected to cost/benefit analysis," said William W. Dodge, DDS, director of professional affairs for the Dental School.
Public education is perhaps the most important way to reduce latex risks, said Amy C. Benedikt, MD, an anesthesiologist and assistant professor at the Health Science Center.
"There is no way to eliminate latex from our environment. Everyone has exposure to latex. Children play with balloons and rubber toys. Adults wash dishes or clean the house using rubber gloves," Dr. Benedikt said.
"But it is important that a patient know whether he or she has latex allergy, and it is very important to tell the physician, the nurse, or the first person the patient sees in a hospital or clinic. And it is just as important for the doctor or nurse to ask patients if they have an allergy to latex," she said.
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