Hyperbaric oxygen therapy in acute necrotizing infections - With a specialreference to the effects on tissue gas tensions

Clostridial gas gangrene and perineal necrotizing fasciitis or Fournier's g angrene are rare but serious infections with an acute onset, rapid progress ion, systemic toxemia and a high mortality rate. The aim of this study was to investigate the efficacy of surgery, antibiotic treatment, surgical inte nsive care and in particular the role of hyperbaric oxygen (HBO) in the man agement of these infections. An experimental rat model was used to investig ate the possibilities for measuring tissue oxygen and carbon dioxide tensio ns during hyperbaric oxygen treatment. In addition to this preliminary expe rimental study, Silastic tube tonometer and capillary sampling techniques w ere tested to measure the effect of hyperbaric oxygen treatment on subcutan eous oxygen and carbon dioxide tensions in patients with necrotizing fascii tis and healthy controls. Between January 1971 and April 1997, 53 patients with Clostridial gas gangr ene were treated in the Department of Surgery, University of Turku. The pat ients underwent surgical debridement, broad spectrum antibiotic therapy and a series of hyperbaric oxygen treatments at 2.5 atmospheres absolute press ure (ATA). Twelve patients died (22.6 %). Hyperbaric oxygen therapy in gas gangrene seems to be life-, limb- and tissue saving. Early diagnosis remain s essential. Patient survival can be improved if the disease is recognized early and appropriate therapy instituted promptly. Between February 1971 and September 1996, 33 patients with perineal necroti zing fasciitis were treated in the Department of Surgery, University of Tur ku. The management included surgical debridement of the necrotic tissue wit h incisions and drainage of the involved areas, antibiotic therapy, hyperba ric oxygen treatment at 2.5 ATA pressure and surgical intensive care. Three patients died giving a mortality rate of 9.1 %. The survivors received hyp erbaric oxygen therapy for 2-12 times. Our results indicate that hyperbaric oxygenation is an important therapeutic adjunct in the treatment of Fourni er's gangrene. Electrical equipment should not be used unsheltered in a hyperbaric chamber due to the increased risk of fire. The subcutaneous tissue gas tensions of rats were therefore measured using a subcutaneously implanted Silastic tub e tonometer and a capillary sampling technique. The method was succesfully adapted to hyperbaric conditions. The subcutaneous oxygen tension levels in creased five fold and the carbon dioxide tension levels two fold compared t o intial levels. The PO2 and PCO2 of subcutaneous tissue and arterial blood were measured di rectly in six patients with necrotizing fasciitis and three healthy volunte ers in normobaric conditions and during hyperbaric oxygen exposure at 2.5 A TA pressure. The measurements were carried out in healthy tissue and at the same time in the vicinity of the infected area of the patients. During HBO at 2.5 ATA subcutaneous oxygen tensions increased several fold from baseli ne values and carbon dioxide tensions also increased, but to a lesser degre e in both healthy and infected tissues. When examining the subcutaneous PO2 levels measured from patients with necrotizing fasciitis, the PO2 was regu larly higher in the vicinity of the infected area than in healthy tissue. I n general, HBO treatment resulted in a marked increase in tissue oxygenatio n in both healthy tissue and in the vicinity of infected tissue. The hypero xygenated tissue zone surrounding the infected area may be of significance in preventing the extension of invading microorganisms.