Latex allergy is an important cause of unexplained perioperative collapse. Anaesthetists must have a high index of suspicion and a clear management plan for the treatment of a patient with this allergy.
Natural rubber latex is a processed plant product, for which over 99% of the world's supply is derived from the latex or the milky cytosol of the tree Hevea brasiliensis, found in Africa and South-east Asia. Latex is produced by specialised lactifer cells and is composed of various chemicals: lipids, phospholipids and proteins. The proteins are responsible for allergic sensitisation predisposing to IgE-mediated reactions. There are 200 other plant species capable of producing latex, but only one other, the guayule bush, has the potential to produce enough for commercial use.
After the harvesting process, ammonia and other preservatives are immediately added to the latex to prevent degradation. Other chemicals, including anti-oxidants (phenylenediamine) and accelerators (thiurams, carbamates), are added to give the latex its desirable properties. The accelerators speed up the vulcanisation or curing process, in which the rubber precursors are cross-linked.
The chemical additives are responsible for some local skin reactions (for example, allergic or chemical sensitivity contact dermatitis), but are virtually never the cause of immediate generalised allergic reactions or anaphylaxis. These latter reactions are almost invariably due to immediate allergic sensitisation to the latex proteins themselves.