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Literature Review

Severe anaphylactic shock without exanthema in a case of unknown latex allergy and review of the literature.

Hollnberger H, Gruber E, and Frank B. Paediatric Anaesthesia 2002;12:544-551

Review: The authors report a case of severe anaphylaxis in an 8 year-old 30 minutes after starting an ileosotomy. He had had 4 prior anorectal operations in the neonatal period. The patient manifested severe bronchospasm and cardiovascular collapse which required 3 resuscitation doses (10 mcg/kg) of epinephrine to reverse. The diagnosis of anaphylaxis was not initially considered because of the lack of a cutaneous rash. Postoperatively, the child received continuous epinephrine and supported ventilation for 25 hours. Subsequent RAST testing was strongly positive for latex and total IgE was elevated, while skin tests to muscle relaxants and lidocaine were negative. Eleven days later the child had another operation using a latex-free protocol without adverse reaction.

An excellent review of the literature follows the case report. I will emphasize the salient points. Sensitization occurs most commonly via the transdermal or inhalational route in adult healthcare workers to the protein hevein, whereas infants and children are sensitized trans-mucosally with the larger protein Hev b1 (rubber elongation factor). Immune reaction type IV is a delayed, cell-mediated allergic reaction most commonly presenting with erythema and blisters 24-48 hours after cutaneous exposure. Type I (anaphylactic) is immediate in onset and due to degranulation of mast cells and basophils which are coated with allergen-specific IgE. This leads to release of histamine, tryptase, leukotrienes, eicosanoids, prostaglandins, and synthesis of cytokines.

Specific risk factors for latex allergy include:
1. Patients having a history of atopy such as asthma, hayfever, atopic dermatitis (which may facilitate transdermal passage of latex proteins from gloves), or food allergy to cross-reacting fruits such as kiwi, banana, and avocado.
2. Patients with anaphylaxis of uncertain etiology, especially when associated with hospitalization, surgery, or dental visits.
3. Patients who have undergone multiple surgical procedures.
4. Patients having repeated catheterization of the bladder.
5. Heath care workers. The incidence of sensitization in physicians and OR nurses is about 10%, and approximately 15% of anesthesiologists test positively. The ratio of asymptomatic to symptomatic anesthesiologists is 4:1.

A strong correlation between the number of operations during infancy and latex sensitization has been shown in several studies. Use of "primary prophylaxis" (defined as avoidance of latex in the OR and postoperatively, and use of latex-free bladder catheters) has been shown to decrease the incidence of sensitization, lower antibody titers, and provide a safe operating room environment. Children with spina bifida have an unexplained biochemical predispostion to latex sensitization independent of the number of surgeries, and latex should be routinely avoided in these patients.

Treatment consists of high suspicion for diagnosis, immediate allergen removal, epinephrine, fluids, antihistamines and steroids. The diagnosis is supported by positive IgE RAST or skin tests to latex. These tests should also be performed to ethylene oxide (used to sterilize endoscopes), which is known to frequently induce sensitization in latex-allergic patients.

Comment: This concise review should be read by all anesthesiologists. An important point regarding OR prophylaxis is to allow 2 hours of latex-free empty room time (~50 room air exchanges) to minimize the amount of airborne latex particles. Pediatric anesthesiologists have a lower rate of sensitization than their adult counterparts, perhaps due to less use of gloves when starting lines. Recently, neonates from our NICU have been coming to the OR scheduled with "latex precautions" even without having spina bifida. This practice is supported by the literature in this review. It seems appropriate that institutions should develop policies on which neonates and infants should have routine latex-avoidance in the OR (for example, those with spina bifida or need for recurrent bladder catheterization or those expected to require multiple subsequent procedures).

Reviewed by: Samuel E. Golden, MD

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