Brown recluse spider envenomation: a prospective trial of hyperbaric
Acad Emerg Med 1997 Mar;4(3):184-192; Maynor ML, Moon RE,
Klitzman B, Fracica PJ,
Canada A; Department of Anesthesiology, Duke
University Medical Center,
Durham, NC, USA.
OBJECTIVES: Loxosceles reclusa (brown recluse) spider bites
can produce severe skin lesions that may necessitate extensive surgical repair. This study delineated the effects of hyperbaric
oxygen (HBO2) therapy on these lesions by performing a prospective controlled animal study.
METHODS: After approval by the Institutional Animal Care and
Use Committee, 41 New Zealand white rabbits
received 64 intradermal injections of 73 microL of raw venom extract mixed with physiologic buffered saline (Dulbecco's solution).
Control injections were made with buffer.
The animals were divided into 5 groups:
1) venom and no HBO2;
2) venom and 1 immediate HBO2 treatment (100% O2);
3) venom and immediate HBO2 with 10 treatments (100% O2);
4) venom and then delayed (48 hr) HBO2 therapy with 10 treatments
(100% O2); and
5) venom and immediate hyperbaric treatment with normal inspired
PO2 for 10 treatments (8.4% O2).
Three animals in group 2 also received a control sodium citrate buffer injection.
HBO2 treatments were at 2.5 atm absolute (ATA) for 90 minutes
Daily measurements were made of the lesion diameter, and skin
blood flow using a laser Doppler probe.
RESULTS: There was no significant effect of HBO2 on blood
flow at the wound center or 1-2 cm from the wound center. Standard HBO2 significantly decreased wound diameter at 10 days
(p < 0.0001; ANOVA), whereas hyperbaric treatment with normoxic (at sea-level) gas had no effect. Histologic preparations
from 2 animals in each group revealed that there were more polymorphonuclear leukocytes in the dermis of all the HBO2-treated
animals when compared with the venom-alone and sodium-citrate controls.
HBO2 treatment within 48 hours of a simulated bite from L. reclusa
reduces skin necrosis and results in a significantly smaller wound in this model. The mechanism appears unrelated to augmented
local blood flow between treatments.