High risk of sensitization to latex in children with spina bifida.

The risk of per-operative anaphylactic shock in response to latex is established in children with spina bifida. This study focuses on 30 children with spina bifida and aims at evaluating the value of predictive tests (skin tests and RAST). No patient had shown a preoperative accident. Hypersensitivity to latex, sometimes suspected by questioning of the patient, was detected 12 times out of 30 (40%). 10 children of the 12 were atopic (83%). The incidence of atopy is significantly higher than that of the general pediatric population (14 out of 30; 46%). This study demonstrates the frequency of the latent hypersensitivity to latex and the subsequent potential risk of per-operative anaphylactic shock. This sensitization can be partly explained by multiple contacts with latex; urinary catheterization several times a day, daily use of latex gloves for routine care, repetitive surgery (more than 8 operations per child). However, atopy increases the risk of sensitization to latex. The authors underline the importance of taking preventive measures for these children such as the use of PVC, silicone or polyurethane catheters and of synthetic rubber. Hypoallergenic gloves are under investigation. A questionnaire and systematic preventive cutaneous assessment before each operation are strongly advised.

[In vivo effects of plasma substitutes on the rheologic properties of blood]. / Effets in vivo de substituts plasmatiques sur les propriétés rhéologiques du sang.

The objective was to investigate in vivo the rheological effects of plasma substitutes (fluid gelatin, dextran 40, dextran 60, hydroxyethylstarch). The study was performed during a hypervolemic hemodilution in 60 adult volunteers who underwent an odontological surgery. Two control groups were infused with Ringer-Lactate or 4% human albumin. Each patient was infused with 500 ml of plasma substitute or control fluid. Blood samples were obtained at four different times: prior to (t0) and immediately after (t1) the infusion, then 3 hours (t2) and 24 hours (t3) after the hemodilution. At t1 and t2, plasma viscosity did not present important variations, except for the group infused with dextran 60 where a significant increase in plasma viscosity was observed. Blood viscosity and erythrocyte aggregation measurements were performed at hematocrit 40% to determine the intrinsic properties of substitute and eliminate the effects of hemodilution. Blood viscosity at high shear rates underwent minor variations in all groups. In contrast, blood viscosity at low shear rate and aggregation parameters exhibited important variations which markedly depended on the used substitute. The infusion of Ringer-Lactate, albumin and dextran 40 induced a significant decrease in blood viscosity and in erythrocyte aggregation. With dextran 60 and gelatin, blood viscosity and erythrocyte aggregation increased. Finally, the infusion with hydroxyethylstarch did not present important differences as compared to the results recorded at t0. Twenty for hours after the infusion, it should be noted an increase in plasma fibrinogen, probably due to surgery, which caused an increase in erythrocyte aggregation in all groups.(ABSTRACT TRUNCATED AT 250 WORDS)

[Allergy to latex]. / L'allergie au latex.

In France 18% of all preoperative allergic shock syndromes result from allergic reactions to latex. IgE antibodies mediate the immediate hypersensitivity reaction to natural latex proteins extracted for the rubber tree (Hevea brasiliensis). Sensibilization occurs after repeated direct contact of the skin or mucosa with latex products including gloves, urinary catheters or after chronic inhalation of airborne particles of latex in the operating theatre. Clinical expressions include skin rash, asthma or anaphylactic shock. During the preoperative period, the shock may occur late after induction of anaesthesia and after the operative procedure has begun or after the arm cuff has been released. In obstetrics oxytocin injection can precipitate the phenomenon. Subjects at risk have been clearly identified: subjects who wear gloves regularly, those working in an environment contaminated with airborne latex, children who have undergone multiple operations on malformations of the urinary tract or who have had repeated catheterisms (40% of the spina bifida patients are sensitized), atopic subjects, those allergic to exotic fruits (banana, avocado, kiwi). These patients should be identified during the preoperative work-up in order to perform allergy tests. The diagnosis of over-sensitivity should be confirmed by prick-tests and perhaps complete antilatex antibody assay and challenge. All material composed of natural latex should be avoided for these patients. Proposed alternatives include synthetic rubber. Hypoallergenic gloves add no further safety. The operative procedure should be conducted using standard techniques.