VOL: 97, ISSUE: 38, PAGE NO: 49
LISA WRIGHT, RGN, Dip palliative care, is immunology nurse specialist
GAVIN SPICKETT, MA, DPhil, FRCPath, is consultant immunologist,STEVEN STOKER, MHSM, is programme leader for user views and risk management, Royal Victoria Infirmary, Newcastle upon Tyne
Latex allergy is on the increase in hospitals and among patients. Two types of allergy are recognised: type I or immediate hypersensitivity, leading to anaphylaxis, and type IV hypersensitivity, leading to contact dermatitis. Type I reactions are associated with IgE antibodies to natural rubber latex, while type IV reactions are mainly associated with the chemicals used to produce latex products. Patients with latex allergy are paradoxically at increased risk of reactions in hospital. This is due to widespread use of latex products and lack of awareness among staff of the risks posed to patients by latex-containing health care products.
Latex allergy is on the increase in hospitals and among patients. Two types of allergy are recognised: type I or immediate hypersensitivity, leading to anaphylaxis, and type IV hypersensitivity, leading to contact dermatitis. Type I reactions are associated with IgE antibodies to natural rubber latex, while type IV reactions are mainly associated with the chemicals used to produce latex products. Patients with latex allergy are paradoxically at increased risk of reactions in hospital. This is due to widespread use of latex products and lack of awareness among staff of the risks posed to patients by latex-containing health care products. A case of severe latex allergy is presented in Box 1 to illustrate the problems that such patients face. As a result of the experiences of this patient an audit of awareness was carried out in the three largest directorates in the trust, demonstrating the poor knowledge of latex allergy among all types and grades of staff. As a result, a clear policy for handling latex allergy was developed and educational training undertaken. Glove policy in the trust has also been reviewed and a glove formulary identified. Increased glove use has occurred to protect staff from the risk of transmissible infections where latex has ideal properties in this respect. Particular risk groups include patients with spina bifida and those requiring multiple operative procedures, particularly where latex is in contact with either mucosal membranes or the peritoneum. Pregnant women form another risk group, as do health care workers. An atopic (hypersensitive) background increases the risk of sensitisation. The topic of latex allergy has been reviewed in detail recently (Cheng and Lee, 1999; Ebo, 2000). Latex is a naturally occurring substance derived from the sap of the rubber tree (Hevea brasiliensis), which under the influence of enzymes present in the sap undergoes a natural polymerisation. Polymerisation is a reaction in which a high molecular weight product is produced by successive condensations of a simpler compound - in this instance, cis-polyisoprene. The sap contains a number of other proteins involved in the polymerisation process and naturally occurring antifungal and antiviral proteins that protect the tree from infection. These substances are conserved in the plant kingdom, so that very similar proteins occur in foods and other plants, leading to cross-reactive allergic reactions (Table 1). The coagulation process can be enhanced by the addition of chemical accelerators and hardening agents. During the curing process the latex is mixed with ammonia and soaked for a variable length of time, during which proteins are leached out, reducing the allergenicity of the final product. However, the trend today is towards a shorter curing process, leaving a final product with a high latex content. Cornstarch is often used during the manufacture of latex gloves to prevent stickiness, but the cornstarch adsorbs significant amounts of latex proteins, which are then aerosolised when the gloves are used, leading to acute bronchospasm in sensitised people. Type I reactions to latex are directed against proteins trapped in the latex polymer, which may be adherent to the cornstarch used in the preparation of gloves and which may become aerosolised. Type I reactions are typically immediate due to the release of histamine from mast cells which have been activated by cross-linking of their bound IgE by the allergen. Late reactions may occur four to six hours later, mediated by leukotrienes synthesised by the activated mast cells. Leukotrienes are a collection of metabolites of arachidomic acid which have powerful pharmacological effects. This reaction gives the typical acute allergic response with urticaria (dermographism), angioedema, hypotension, bronchospasm and vomiting and diarrhoea. Type IV reactions occur much more slowly, over a period of three to five days, and are mediated by an influx of activated T-lymphocytes into the site of allergen application. The T-cells and local macrophages release inflammatory cytokines. These are immune mediators that cause the eczematous reaction with erythema, vesiculation and itch. There is no evidence that it is the naturally occurring latex proteins that cause these reactions; rather, the chemicals added as accelerators and hardeners cause them. These agents can also cause a non-immune irritant reaction, typically causing redness and cracking of the skin. Type I allergic responses are diagnosed from a typical history of acute reactions following exposure to latex containing products. Tables 2 and 3 give details of the commonest hospital and domestic items that may contain latex and pose a risk to the latex-allergic person, but these lists are not exhaustive. Specific IgE can be detected in the blood in 85-90% of allergic people. Skin-prick testing (SPT) with standardised extracts of latex proteins is more sensitive and specific and is the test of choice, unless there is a significant risk of anaphylaxis. SPT cannot be carried out in patients with significant skin disease, dermographism or those who are taking antihistamines. Several studies on surgical and outpatient populations have shown IgE-mediated latex allergy of 6-7%. For health care workers the figure is approximately 8-12%, but high levels (15-20%) have been noted in some studies of high-risk areas, such as operating theatres. These higher figures, however, include staff with type IV-reactive rather than IgE-mediated allergy. Fifty to sixty per cent of patients with Type I latex allergy will have other atopic diseases, and in patients being investigated for other allergic diseases, 12% were found to have latex-specific IgE. The precise incidence of acute severe allergic reactions in the UK is not known, as there is no formal mechanism for collecting data. The Health and Safety Executive has recently made it clear that it will be paying particular attention when inspecting hospitals to the safeguards and policies regarding the use of latex products. There is a considerable amount of legislation that is relevant to the use of latex in the workplace, well reviewed by the RCN and also in the Association of NHS Occupational Physicians’ guidelines (ANHOPS Executive, 1999; RCN, 1999). All trusts must have a robust risk management policy for latex allergy, both for staff and for patients. Audit
Our experiences with the patient described in Box 1 encouraged us to take the lead in developing hospital policies for managing patients and staff with latex-related problems, in conjunction with the trust’s risk management committee. As part of the process, it was felt that it would be useful to undertake a survey of medical and nursing staff’s knowledge of the problems of latex allergy before formal guidance was issued. A one-page questionnaire was constructed and circulated to medical and nursing staff in three directorates - medicine, surgery and women’s services - on two hospital sites. Forms were completed anonymously and analysed by the Department of Clinical Audit. Results
A total of 373 forms were returned. There was no significant difference between the mean and median scores, although there was a trend towards higher scores in the returns from women’s services. This is explained by a delay in sending these out, allowing some respondents to have attended a study day on the topic. When the returns from the medical directorate were analysed by grade of staff there was a trend for higher scores by senior house officers and pre-registration house officers, but the total number of returns were small. This is likely to reflect exposure to earlier teaching organised by one of us for students and MRCP candidates. Overall, there was no great difference between the knowledge of nurses compared to doctors. When the responses to the individual questions were analysed it was clear that there was ignorance about the potential for cross-reactions with foods and about the expected level of allergy among hospital workers. Two thirds of staff thought that routine observations (for instance, using a blood pressure cuff) and the administration of IV drugs into a giving-set line would be safe for a latex-allergic patient (both pieces of equipment might possibly contain latex) or did not know whether it was safe. A quarter of staff thought that all patients with a severe allergic reaction to latex would develop urticaria, whereas acute anaphylaxis is only accompanied by urticaria in 50% of cases. The majority of staff did not realise that latex-allergic patients should be nursed in a cubicle where their environment could be controlled. Discussion
The survey showed that awareness of the problems of latex allergy were poorly understood by hospital staff in the three directorates surveyed, although there were some well-informed individuals. To address this, a half-day course was organised for trust staff, at which the results of the audit were discussed and specific sessions were directed at the diagnosis and management as well as the occupational and risk management aspect of latex allergy. Guidelines for the management of latex-allergic patients and staff have now been produced and will be circulated. These have been based on available published data and take into consideration the legal framework. An important aspect of the management of latex-allergic patients has been the identification of contacts in the supplies department who are able to research accurately and rapidly the provision of latex-free alternatives for clinical staff. It is also important that staff can quickly access advice on the management of latex-allergic reaction in patients and staff. This has resulted in close collaboration between the departments of immunology, dermatology and occupational health. It is essential that areas receiving emergencies have immediate access to latex-free equipment. This involves planning by each department to produce lists of equipment likely to be required for emergency treatment and to ensure that these are stored in a clearly marked box whose location is known to and accessible to all staff. Particular risks areas are A&E, acute medical admitting areas, theatres and delivery suites. Cardiac arrest trolleys also need to be reviewed. Hospitals need to consider how they may reduce the risk of sensitisation developing. Use of powder-free gloves is one step, but these are not latex-free. Unfortunately latex-free gloves are more expensive than their latex equivalent, and in some respects considered inferior - for example, in preventing transmission of infection or in surgical ‘feel’. However, it is likely that, as use of non-latex gloves increases, the price will fall. In the USA, the Food and Drugs Administration has made it mandatory for medical devices containing latex to be labelled, but this is not yet a requirement in the UK. As a direct result of the ongoing risk management process, our trust has initiated a review of glove usage and has included allergenicity as one of the criteria for evaluating gloves for inclusion in the trust’s glove formulary.