Friday, August 05, 2005

Brown Recluse Spider Injury, Hyperbaric oxygenation?


The brown recluse spider bite is an injury that has been shown to respond to hyperbaric oxygenation treatments. Necrotizing arachnidism is a complication of the brown recluse spider bite which is characterized by progressive necrosis and inflammation of the tissue at the site of the spider bite. Diagnosis in most cases is purely presumptive and often made in retrospect by the signs and symptoms that later develop. The degree of the clinical response is relative to the amount of venom injected, location of the bite (with high fat areas being more severely affected) and the immune status of the patient.

Photos:
http://www.lib.uiowa.edu/hardin/md/brownrecluse.html
http://www.emedicine.com/derm/topic598.htm

It has been shown in at least one good study at Duke University that HBO is effective in reducing the necrosis of the toxin.

Brown recluse spider envenomation: a prospective trial of hyperbaric oxygen therapy.
Acad Emerg Med. 1997 Mar;4(3):184-92.
Maynor ML, Moon RE, Klitzman B, Fracica PJ, Canada A.

Department of Anesthesiology, Duke University Medical Center, Durham, NC, USA. mmaynor.103@aol.com

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 (HBO) 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 HBO; 2) venom and 1 immediate HBO treatment (100% O2); 3) venom and immediate HBO with 10 treatments (100% O2); 4) venom and then delayed (48 hr) HBO 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. HBO treatments were at 2.5 atm absolute (ATA) for 90 minutes twice daily. Daily measurements were made of the lesion diameter, and skin blood flow using a laser Doppler probe. RESULTS: There was no significant effect of HBO on blood flow at the wound center or 1-2 cm from the wound center. Standard HBO significantly decreased wound diameter at 10 days (p