[abstract] PROSPECTIVE SERIAL TRANSCUTANEOUS HYPERBARIC OXYGEN CHALLENGE MEASURES IN PROBLEM LOWER EXTREMITY WOUNDS.

Abstract

BACKGROUND: Juxta-wound transcutaneous oxygen (PtcO2) measurements determine the need for hyperbaric oxygen (HBO) therapy using hypoxic thresholds at ambient pressures. We have used a juxta-wound hyperoxic PtcO2 response of >= 200 mmHg during a HBO challenge at 2.0 ATA and have retrospectively shown a 86% positive predictive value (PPV) with a 36% negative predictive value (NPV) for wound healing. This study prospectively evaluates this threshold for wound healing in selected problem lower extremity wounds. METHODS: Patients were prospectively selected for serial PtcO2 measurements after clinically determined to receive wound management that included HBO therapy. Both PtcO2 and PtcCO2 were measured with a Radiometer TCM3 ® at a single juxta-wound site during I ATA air and during a HBO challenge at 2.0 ATA for 60 minutes. This test was repeated on days 1,3, (initial) and days 10 and 21 during the course of HBO therapy. Wound outcome was clinically determined as healed or not healed. RESULT: Two initial tests were done on 31 patients and subsequent tests on 17 patients. A PtcO2 value at any time during the test >= 200mmHg signified a favorable healing response for HBO therapy. Patients healed: 22/31. Predictive indices of PtcO2, One initial test >= 200 mmHg, Two initial tests >= 200 mmHg, Two initial tests (1 ATA) <= 30 mmHg; Sensitivity, 90, 100, 40; Specificity, 45, 64, 91; PPV, 75, 91, 88; NPV, 71, 100, 46; Overall accuracy, 74, 87, 58. Ten-day repeat tests reflected initial responses in 15/17 patients. Two patients with initial borderline responses changed to a positive response after 10 days. No changes were seen in measures from days 10 to 21, n=7. No predictive changes were seen with PtcC02 measures. CONCLUSIONS: These prospective data indicate that a HBO challenge Ptc02 threshold >= 200mmHg can be useful in predicating a favorable response to HBO therapy in selected lower extremity wounds.