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Latex allergy

Latex allergy
Michael Richards
Background
Latex is the sap of Hevea brasiliensis (the rubber tree). It is a complex mixture of polyisoprene particles in a phospholipoprotein envelope and a serum containing sugars, lipids, nucleic acids, minerals, and proteins. Latex is made heat stable and elastic by vulcanization (heating in the presence of sulphur). Chemicals such as accelerators and antioxidants are also added to enhance strength, stretch, and durability.
Latex is found in many of the products used in the operating environment, including gloves, urinary catheters, syringes, drug vial stoppers, intravenous giving sets, intravenous cannulas, injection ports, masks, airways, endotracheal tubes, rebreathing bags, bellows, and circuits. Many pieces of surgical equipment also contain latex, including drains, bulb irrigation syringes, vascular tags, and rubber shod clamps.
Epidemiology
Development of latex sensitivity is dependent on previous exposure. There are certain groups at particular risk of developing latex sensitivity:
  • Health care workers: estimates have put the risk of developing latex sensitivity at between 5 and 17%, depending on the degree and nature of exposure; the actual figure may well prove to be much higher (up to 50%).
  • Rubber industry workers: there is an increased incidence of positive skinprick tests to latex, and chronic respiratory symptoms associated with eosinophilia in this population.
  • Neural tube defects (including spina bifida): the reported incidence of latex sensitivity due to recurrent bladder catheterizations is estimated at between 20 and 65%.
  • Fruit allergy: an association between latex and fruit allergy has been described, and cross-reactivity demonstrated with certain fruit allergens (banana, avocado, passion fruit, tomato, grape, celery, kiwi fruit, chestnut).
Spectrum
  • Irritant contact dermatitis: non-allergic irritant contact dermatitis occurs due to damage of the skin from irritation of an exogenous substance.
  • Contact dermatitis: a type IV (delayed) hypersensitivity reaction based on allergic sensitization. Presents with an eczematous eruption, which can then progress to lichenificaton and scaling on chronic exposure. Mediated by T lymphocytes exposed to chemicals added in the vulcanizing process such as the accelerators (thiurams and thioureas) and antioxidants (benzothiazoles).
  • Type I hypersensitivity: IgE-mediated type I hypersensitivity has been attributed to water-soluble proteins in latex and starch powder-bound proteins. Clinical manifestations may result from exposure to latex via a variety of routes including skin, mucous membranes, inhalation, and intravenous. The three main presentations are:
    • Contact urticaria: particularly in health care workers, typically 10–15 min following, and usually at the site of, exposure. This may be the initial step in the progression to more severe reactions.

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    • Asthma and rhinitis: characterized by bronchial obstruction and secretions. Starch powder used as a lubricant for gloves has been implicated here.
    • Anaphylaxis, vascular collapse, and shock: this is most commonly encountered intra-operatively and although intravenous and mucus membrane inoculation are the most common triggers, anaphylaxis has been described with donning of gloves and indirect contact with individuals who use latex gloves.
Clinical features of latex anaphylaxis
A careful history with particular reference to risk factors is important preoperatively to give an indication of potential problems. Onset is normally delayed by 20–60 min following exposure to the antigen and progressively worsens over 5–10 min. The reaction presents with hypotension, rash, and bronchospasm (rash may be absent). It may be difficult to exclude anaphylaxis from anaesthetic drugs since this presents in a similar manner and is treated in the same way (see p. 857). Subsequent analysis of serum mast cell tryptase confirms anaphylaxis and skin-prick testing will determine the causative factor.
Management of elective surgery
  • The prophylactic use of antihistamines and corticosteriods has not been established.
  • The patient should be scheduled first on the operating list (latex can remain in the air).
  • Items to be particularly careful of include BP cuff, gloves, urinary catheters, anaesthetic reservoir bag/face masks, syringes, elastic in disposable hats/TEDS/underpants, IV giving sets, drug vials with latex stoppers.
  • Many companies are now moving towards latex-free equipment, but each theatre suite should have a list detailing which equipment is guaranteed latex free.
  • The LMA (Intavent) is latex free.
  • If uncertain about the BP cuff, wrap plastic sheeting around the arm prior to placement.
  • Most ETTs and airways are latex free.
Every department should have a latex-free trolley containing the following:
  • Non-latex gloves. Note that ‘hypoallergenic’ gloves are non-standardized and are often made from latex. Gloves used in patients allergic to latex should be made of synthetic rubber such as neoprene or polyvinyl chloride, e.g. ‘Derma Prene’ Ansell Medical or ‘Neotech’ Biogel.
  • Latex-free equipment including masks and airways (plastic), endotracheal tubes (PVC), reservoir bags (neoprene), valves (silicon), IVI tubing, bellows, and circuits.
  • Latex-free (or glass) syringes.
  • Latex-free (or Teflon) intravenous cannulas.
  • Barrier protection for placement between latex-containing items and the patient’s skin (e.g. Webril).
  • Drugs for treatment of anaphylaxis and latex-free resuscitation equipment.

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Further reading
Kam PC, Lee MS (1997). Latex allergy: an emerging clinical and occupational health problem. Anaesthesia, 52, 570–5.

Woods JA, Lambert S (1997). Natural rubber latex allergy: spectrum, diagnostic approach, and therapy. Journal of Emergency Medicine, 15, 71–85.

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