General information on latex

Latex is a resinous sap produced by a tropical rubber tree, HEVEA BRASILIENSIS, which spontaneously grows in the equatorial forests of South-America. After incision, their trunks exude a milky fluid containing 33% of rubber (cis-1,4 polyisoprene), 2% of resin, 65% of water, 1,8% of proteins. Ninety percent of this fluid is coagulated and used for the manufacture of handmade articles, such as tires and stamps; the remaining 10% is added to ammonia, in order to avoid bacterial contamination, and to stabilizers, antioxidants, accelerants and vulcanizing agents^2-3-6.

Epidemiology

The first report of latex sensitization dates back to 1979, as a consequence of contact with natural rubber gloves for domestic use. From then on, there was a rapid increase in adverse reactions, ascribable to latex exposure. From 1992 to 1998, the Food and Drug Administration (FDA) received more than 1000 reports of adverse reactions to latex products, with as many as 15 fatal cases. Excluding the atopic subjects, the prevalence in the general populations is around 1-2%. The risk is higher in some specific professions:

·         Health staff: the prevalence varies according to the degree of exposure (it is higher among the staff in charge of operating rooms, intensive care units, emergency areas and among dental surgeons)^4-5. On the basis of the available data, it was calculated that 10-17% of health staff are sensitized, 3-7% have a set of symptoms related to latex exposure and 2% suffer from occupational asthma secondary to contact with the allergens present in this material.

·         Rubber industry staff: the prevalence varies from 1.5 to 11% (it is lower in industries with a higher degree of automation).

·         Atopic subjects: the prevalence can reach 35%⁷.

·         Subjects undergoing repeated surgical operations (e.g. children affected by spina bifida or urogenital anomalies): the prevalence varies from 18 to 27% in children with spina bifida.

There are also predisposing conditions that increase the incidence of latex sensitization: according to the results of some studies, over 50% of health staff with an allergy to latex had a clinical history of hand dermatitis or it was atopic. Besides, there is an increased risk in subjects with food allergies as well as in women, more exposed to this material for both occupational and non-occupational reasons^{8-9-10-12-13-17-18-19}.

In symptomatic subjects, the continued exposure to latex products seems to cause an increase in the degree of sensitization, with possible clinical manifestations evolving into worst reactions, of anaphylactic type too.

Etiopathogenesis and symptomatology

Latex contains over 200 polypeptides, 50 of which have been characterized as allergens¹¹. These allergenic proteins perform different functions:

–        Some form a defense system

–        Others intervene in the synthesis of rubber (for instance: Hev b 1 and Hev b 3)

–        Others, on the contrary, are structural proteins

There are specific patterns of sensitization according to the occupation, the type of manufactures one come in contact with, the ways of sensitization and the genetic substratum:

ü  health staff is mainly sensitive to Hev b 5 and Hev b 7,

ü  subjects with spina bifida are more frequently sensitive to Hev b 1, l’Hev b 3 and lately also to Hev b 7.

Latex sensitization usually occurs as a consequence of direct contact with the material, but it can also occur after allergen inhalation. A few substances like cornstarch, added as a lubricant in order to enhance the “wearability” of the glove, facilitate air dispersion of the sensitizing proteins and therefore cause inhalation^14-15-16.

In the USA, already from September 30, 1998, FDA forced the manufacturing industries to indicate, on the product labels, the potential allergenicity of latex products. According to recent standards, fixed by the American Society for Testing and Materials, gloves with a protein content lower than 200 mcg/g should be preferred (the protein content is reported on the box); whereas the European Norm 455-3, determining the qualitative standards of gloves and their methods of control, indicates a protein content lower than 50 mcg/g.

Latex exposure can cause two types of reactions, of immunologic or irritative nature:

Irritative reactions especially appear as irritating contact dermatitis, which usually occurs as a consequence of contact with latex gloves.

Immunological reactions are, in most cases, ascribable to two different pathogenetic mechanisms:

·         Type I hypersensitivity reactions, immediate or IgE-mediated: in subjects sensitized to latex protein, who come in contact with allergens, there is a massive production of IgE which bind to specific receptors on basophils and mast cells, causing the degranulation of these cells and the consequent release of histamine and other anaphylaxis mediators. According to the type of contact, there could be urticaria, in case of contact with handmade latex products, or anaphylaxis, in case of skin, mucosal, inhaling and especially parenteral exposure. The risk is essentially linked to the quantity of allergens and to the rapidity they penetrate the human body.

·         Delayed or cell-mediated hypersensitivity reactions: they are caused by direct contact with additives used in the rubber manufacture or with latex proteins present in gloves, shoes, sportswear and medical instrumentations, even during the airborne phase. The clinical manifestations are initially located in the contact area (usually skin, oral cavity and genitals) and then can extend to other parts. Unlike Type I hypersensitivity reactions, the type of lesion differs according to the stage of the disease: in the acute stage they are erythematous, edematous and vesicular; in the subacute stage there is a reduction of erythema and the appearance of crusts and skin exfoliation, correlated with serous exudation; in the chronic stage there is hyperkeratosis and fissured skin. Lesions appear 48 hours after antigen exposure. However, in literature there are a few cases of “protein contact dermatitis”, with a mixed pathogenetic mechanism and a clinical picture of vesiculation and immediate onset^6-7-8-9.

Diagnosis

The identification of a patient who is unaware of being allergic is a an essential prerequisite to guarantee adequate health services. The diagnostic procedure is based on a thorough case history, by means of a specific questionnaire (Table 2). If the answers suggest a latex allergy, the patient will be directed to the Allergology and Clinical Immunology Unit for an allergological examination, and then the results will be sent to the clinician who asked this advice. Case history, as appealing as it can be, is only indicative of a possible latex allergy, because the symptoms can be atypical, soft, or masked by the concomitant presence of an irritative dermatitis, as happens in the forms caused by gloves. Consequently, the diagnosis is based on in vivo and in vitro examinations^20-21-22-23.

In vivo tests

1.      Skin Prick Test (SPT): it is positive if there are specific IgE on skin mast cells, but it does not define the etiological role of latex. Negativeness could be explained with a recent district sensitization. The wheal size is correlated with the severity of symptoms.

2.      Provocation Test: it is the only test capable of proving the responsibility of latex for hypersensitivity reactions. The patient puts a glove finger on his clammy hand and then, if necessary, puts on the whole glove. The test should be done by experienced staff in the hospital environment and the patient should be kept under observation for the time necessary to avert late reactions. It should not be used in patients with an history of anaphylactic shock and with active hand dermatitis.

3.      Patch Test: it is done after eczema diagnosis, and allows to reach a differential diagnosis between irritative and allergic forms. The back of the patient’s hands are kept into contact with latex haptens for 96 hours.

In vitro tests

1.      Dosage of specific IgE: it is divided into three different tests, CAP – RAST, AlaSTAT, HY-TEC. The latter is the most sensitive, but is less specific than the other two.

Therapy

The therapy of a possible allergic reaction will be given according to the type of reaction.

In case of type IV eczematous reactions, the Authors suggest the topical use of cortisone and per os administration of antihistamine.

Therefore, the topical therapy will be suggested as symptomatic treatment:
• In the acute vesicular stage, we can use a commercial preparation of aluminum subacetate (BUROWS), to be applied twice a day to the symptomatic area. It is also useful to make use of galenic preparations based on camphor, menthol and hydrocortisone (ex: Sarnol HC) or of mild topical anesthetics (such as PRAMOXINE) with a demulcent and antipruritic effect.
• In the subacute stage of contact dermatitis, an emollient lotion (Eucerin) or an ointment can be applied to the clammy skin.
• Obviously, corticosteroid creams or ointments (like hydrocortisone), fluorinated or nonfluorinated, have a good anti-inflammatory effect and are useful both in subacute and chronic contact dermatitis.

The systemic therapy is given to prevent severe atopic reactions and treat the widespread multifocal allergic manifestations.
Symptoms such as intense itching or a feeling of intense warmth in specific parts of the body can be relieved by means of sedative antihistamines, such as diphenhydramine hydrochloride (Benadryl), hydroxyzine hydrochloride (Atarax), or doxepin hydrochloride (Sinequan), to be administered in the night to reduce to a minimum the drowsiness caused by these drugs. Most of the cases of acute contact dermatitis are effectively managed without the use of systemic corticosteroids, but short courses of treatment with systemic corticosteroids are recommended for severe vesicular eruptions on the hands, feet or face, while for incoercible atopic forms, the use of non-corticosteroid symptomatic drugs is recommended. From time to time, a secondary infection occurs as a complication of the mucocutaneous manifestations: in this case, systemic antibiotics can be recommended.

In case of Type I reactions, the therapy changes according to the clinical picture, up to an intensive treatment of the anaphylactic shock by using adrenalin, a lifesaving drug due to its therapeutic effectiveness in IgE-mediated allergic reactions.

Materials and Methods

·         Hospital ward

In case of hospitalization of a patient allergic to latex, the clinician arranging the admission, after proving the allergy, is supposed to arrange a “latex safe” environment for the patient. If the Unit lacks of a latex-free cart, it will be asked to the Unit of reference where the bed is available. It will be placed inside the room with the allergic patient. In this room there should not be any product containing latex.

During hospitalization, the paramedical staff will prepare the patient’s environment by indicating “Latex-Free” on a notice outside of the room. A similar notice should be placed on the bed, together with the indication of the patient’s allergic condition on the medical records.

In the room there should be no latex products and, in the absence of alternative manufactures, the parts in latex should be properly covered^{1-2-3-4-5-24-25-26}.

The patient should be placed in a single room (make sure to use latex-free mattress and pillow). If it is not possible, the other in-patients sharing the same room should be all considered as allergic. Therefore, the health staff should put on latex-free gloves, or at least powder-free latex gloves, for the assistance of the other in-patients, in order to reduce the level of airborne particles.

It is important to keep the allergic patient away from latex products as much as possible. This implies that blood samples, specialist examinations, diagnostic and instrumental exams (ECG) should be taken inside the patient’s room as far as possible.

Outside of the room there should be disposable gowns, which the hospital staff should wear before entering the room. In addition, the staff should always thoroughly wash their hands before entering the room.

In the room there should always be a general list of drugs certified as containing latex or not. Particular attention should be paid to injectable drugs, to be drawn into a latex-free syringe from glass phials or bottles that do not contain latex, even in the cap. If the cap contains latex, it should not be perforated but needs to be completely removed^{1-2-3-4-5-6-26-27}

If the patient has to be moved, this should happen without any exposure (contact, inhalation, ingestion) to latex, and he should be followed by the clinical records indicating his allergic condition. This condition should be made explicit on any request of exams.

Cleaning staff, as well as cooks and employees in charge of the distribution of meals, should be informed about the presence of a patient allergic to latex, and for this reason they should take wise precautions, such as do not wear latex gloves. Moreover, the diet of patients allergic to latex should exclude food that is cross-reactive with latex (e.g. banana, kiwi, chestnut) ^{1-4-5-6-27-28-29-30}.

·         Operating room

The person responsible for the operating room should arrange a “latex safe” environment, prepare the room and indicate, by means of a notice, that an operation in a latex-free environment is in progress.

The preparation of the operating room and recovery room should be carried out by trained staff without latex gloves; they should move all the materials and equipments outside of the room, if possible, and then readmit only the essential materials after checking they are latex-free. The latex products that cannot be replaced (e.g. mattress) should be covered with cotton sheets or thin transparent plastic materials. Latex devices should be avoided in the preparation of the patient for the surgical operation.

Within the room there should be a cart with all the latex-free materials necessary for the operation. This cart should be prepared in a different room, in order to avoid contamination with airborne particles. The materials in the cart need to be selected and prepared specifically for the type of patient and the type of surgery. Each device, comprised in a checklist, is preventively chosen by the surgeon, who makes also use of the charge nurse’s help. The checklist should indicate the patient’s name, the date and the signature of the person who compiled it.

For emergency operations, a cart with standard latex-free materials should be available.

In the operating room there should always be a list of the materials that should never be used (e.g. latex gloves).

Each person involved in the management of the patient should be adequately informed that the patient is allergic, while entry into the room of people not directly involved in the operation is strictly forbidden.

The staff, before entering the room, need to wear disposable gowns and use masks without elastic bands and overshoes if clogs contain latex.

·                              Preparation of the patient

It is advisable to make preparation and recovery within the operating room and, only when the patient is self-sufficient, he can be moved into his room, without the help of a patient transfer unit, unless this is latex-free.

Even though there are contrasting opinions, in case of surgical operation on a patient allergic to latex, prophylactic measures are usually preferred by making use of antihistamine and cortisone, according to the following pattern:

1 hour before surgery the clinician should administer:

1 phial containing 50 mg Farganesse I.M.

1 phial containing 50 mg Ranidil I.V.

1 hour, 7 hours and 13 hours before surgery the clinician should administer:

1 phial containing 40 mg Solumedrol I.M.

·             Surgery planning

Operations should be planned for Monday morning, after having prepared the room the previous Friday and without having used the same room on the weekend; if this is not possible, the room should be prepared with a complete change of the air during the six hours preceding the operation.

If it is impossible to perform surgery on Monday morning, it could be planned as the first of the day, after dusting any surface in the room with the wet technique, in order to remove the latex particles settled during the night^1-2-3-4-5.

Clinical case

On 3/18/2008 the Authors admitted, in “day-surgery”, 2 patients with a positive case history and a clinical history of allergy to latex. Before admitting the two patients, the paramedical staff prepared a room removing latex products, according to the “Latex-Free Protocol”: they affixed a notice stating “Latex-Free” both on the bed and outside of the room. In the room they also placed a cart containing “Latex-Free” material, while outside there was a cart containing disposable gowns to be used before entering the room. All the medical staff, paramedics, cleaners and employees in charge of the distribution of meals were fully informed about how to behave. The diet of patients allergic to latex excluded food that is cross-reactive with latex (e.g. banana, kiwi, chestnut). When the patients arrived, meticulous attention was paid in order to avoid any contact with latex materials, by creating a “Latex-Safe” environment both during their stay in hospital and their instrumental exams (blood examinations and X-Rays, done during the same day of their admission).

Both patients required a drainage of the oral cavity due to focal infections. During the same day, both patients were moved to the operating room, which had been previously prepared. Indeed, materials and equipments were all moved outside of the room, when possible, and then only latex-free materials were reintroduced into the room. Latex materials necessary for the operation were covered with a multilayer transparent plastic material. A cart containing all the latex-free materials necessary for the operation was placed inside the room, previously prepared in a different room, in order to avoid contamination with airborne particles. In addition, a list containing the materials that should never be used in the operating room was affixed. The staff of the operating room was adequately informed and, before entering the room, they wore disposable gowns, masks without elastic bands, and overshoes if their clogs contained latex; entry into the room of people not directly involved in the operation was strictly forbidden, and inside the room there was a reduced number of clinicians and paramedics. Before surgery, on both patients was performed a venous access as a prophylactic measure. Subject to infiltration of local anesthetic without vasoconstrictor, avulsion of the damaged teeth was performed, followed by alveolar wash, tamponade with oxidized regenerated cellulose and reabsorbable suture. Both patients were prescribed home antibiotic and antiphlogistic therapy, and were suggested to have a liquid and cold diet for two days. The two patients were discharged the same day.

Discussion

The increasing use of gloves and other latex products explains the increasing sensitization to this substance both in the health staff and in the general population. The allergic reactions can have an immunologic or irritative nature and the set of symptoms is extremely varied, because there can be contact urticaria, widespread urticaria, ocular and respiratory manifestations, angioedema and anaphylaxis. This depends on the type of exposure, number of allergens and their rapidity to penetrate the human body. Fortunately, the prevalence of latex sensitization in the general population is below 1%. But there are a few professions at a higher risk (health staff, atopic subjects, rubber industry staff and subjects undergoing repeated surgical operations), where the prevalence is higher. Due to this important set of symptoms, it is of primary importance to adopt the proper diagnostic procedure, based on a thorough case history and allergological tests. In subjects allergic to latex, it is fundamental to arrange the proper therapeutic control, during their stay in hospital and during surgery in the operating room, in order to minimize contact between latex allergens and patients.

Conclusions

Latex allergy is a rare occurrence, but it has been increasing in recent years. About the diagnostic procedures to follow, these allergy should always be considered by means of a thorough case history. A suspected latex allergy needs to be confirmed by means of allergological tests. In view of the possible risks related to latex allergy, it is of the utmost importance to perform any dental operation in allergic patients with respect of specific protocols. The protocol that the Authors suggested, comprising the series of precautions previously listed, tends to minimize or remove possible contact with latex materials of patients allergic to this substance: this allows to avoid the dramatic and uncontrollable consequences that may sometimes arise.

AUTHOR

F. INCHINGOLO*^1,2, M. TATULLO¹, A. D. INCHINGOLO², A. L. VALENZANO¹, A. PALLADINO¹, M. W. MARRELLI², R. CORELLI ³ , F. M. ABENAVOLI⁴ , V. Picciariello¹, A. M.   INCHINGOLO¹ , G. DIPALMA^{1 ,2}

* Assistant Professor. University of Bari. Department of Odontostomatology and Surgery. Director: Prof. R.F.GRASSI. CLSOPD Bari. Dean: Prof. G. F. FAVIA. Top Clinician at Calabrodental Srl, Maxillofacial Surgery Unit, Crotone – Operating within the National Health Service, Calabria Region(ITALY)

¹ University of Bari. Department of Dental Science and             Surgery, Director: Prof. R. F. GRASSI. CLSOPD Bari. Dean: Prof. G^. FAVIA.

² Calabrodental Srl, Maxillofacial Surgery Unit, Crotone – Operating within the National Health Service, Calabria Region(ITALY)

³ University of Bari. Department of Maxillofacial Surgery Director: Prof. R. Cortelazzi.

⁴ “S. Pietro – Fatebenefratelli” Hospital, Roma. Department of Otorinolaringoiatry.

⁵     Dentist in Chieti (ITALY)