Soft tissue

Tissue gas tensions were determined in 6 patients with necrotizing fasciitis and in 3 healthy controls by Korhonen66. Samples were taken from healthy distant tissue and in the vicinity of the infected area. Baseline values while breathing room air were 87mm Hg in the healthy brachial subcutaneous tissue and 92mm Hg in the infected area. The mean PO2 value obtained from the healthy tissue was lower (283mm Hg) than that near the infection site (387mm Hg) during the hyperbaric session at 253.2kPa (2.5ata) for 100 minutes, with a concomitant mean arterial pO2 of 742mm Hg. This behaviour may be attributed to increased microcirculation enhancing the inflammatory response to infection or due to impaired local oxygen utilization.

Non-healing chronic wounds are often treated with HBO to restore tissue oxygen levels in ischemic areas. Measurements of tissue oxygen pressures permit the correlation of structural changes in the tissue with local oxygen levels. Siddiqui67 evaluated tissue responsiveness to 14 versus 5 serial HBO treatments in terms of tissue oxygen tensions in the ischemic rabbit ear model. 31 female New Zealand White rabbits underwent selective arterial division at the base of one ear, the other one served as an internal non-ischemic control. Nine of them received only NBO, the others HBO and NBO. Tissue responsiveness was defined as the plateau PtiO2 achieved during NBO exposure. The ischemic rabbit ears receiving 14 daily treatments achieved statistically significant higher tissue oxygen tensions under hyperbaric conditions (253.2kPa [2.5ata], 90minutes) and during HBO exposure than the other groups. On contrary, the behaviour of tissue oxygen tensions during breathing of normobaric air within each group did not differ significantly between baseline values and those after 14 days of HBO treatment. HBO is considered to act as a signal transducer beyond its energy-generating effect in wound healing.

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