BROWN RECLUSE SPIDER ENVENOMATION - A PROSPECTIVE TRIAL OF HYPERBARIC-OXYGEN THERAPY

Objectives: Loxosceles reclusa (brown recluse) spider bites can produc e severe skin lesions that may necessitate extensive surgical repair. This study delineated the effects of hyperbaric oxygen (HBO) therapy o n these lesions by performing a prospective controlled animal study. M ethods: After approval by the Institutional Animal Care and Use Commit tee, 41 New Zealand white rabbits received 64 intradermal injections o f 73 mu L of raw venom extract mixed with physiologic buffered saline (Dulbecco's solution). Control injections were made with buffer, The a nimals were divided into 5 groups: 1) venom and no HBO; 2) venom and 1 immediate HBO treatment (100% O-2); 3) venom and immediate HBO with 1 0 treatments (100% O-2); 4) venom and then delayed (48 hr) HBO therapy with 10 treatments (100% O-2); and 5) venom and immediate hyperbaric treatment with normal inspired PO2 for 10 treatments (8.4% O-2). Three animals in group 2 also received a control sodium citrate buffer inje ction. HBO treatments were at 2.5 atm absolute (ATA) for 90 minutes tw ice daily Daily measurements were made of the lesion diameter, and ski n blood flow using a laser Doppler probe. Results: There was no signif icant effect of HBO on blood flow at the wound center or 1-2 cm from t he wound center. Standard HBO significantly decreased wound diameter a t 10 days (p < 0.0001; ANOVA), whereas hyperbaric treatment with normo xic gas had no effect. Histologic preparations from 2 animals in each group revealed that there were more polymorphonuclear leukocytes in th e dermis of all the HBO-treated animals when compared with the venom-a lone and sodium-citrate controls. Conclusion: HBO treatment within 48 hours of a simulated bite from L. reclusa reduces skin necrosis and re sults in a significantly smaller wound in this model. The mechanism ap pears unrelated to augmented local blood flow between treatments.