Potential markers of healing from near infrared spectroscopy imaging of venous leg ulcer. A randomized controlled clinical trial comparing conventional with hyperbaric oxygen treatment

The aim of this study is to ascertain whether the simultaneous measurement of hemoglobin O2 saturation (StO2) and dimension of venous leg ulcers (VLU) by near infrared spectroscopy (NIRS) imaging can predict the healing course with protocols employing a conventional treatment alone or in combination with hyperbaric oxygen therapy (HBOT). NIRS 2D images of wound region were obtained in 81 patients with hard-to-heal VLU that had been assigned, in a randomized controlled clinical trial, to the following protocols: 30 HBOT sessions, adjunctive to the conventional therapy, either twice daily over 3 weeks (group A) or once daily over 6 weeks (group B), and conventional therapy without HBOT (group C). Seventy-three patients completed the study with a total of 511 NIRS images being analyzed. At the end of treatment, wound area was significantly smaller in all three groups. However, at the 3-week mark the wound area reduction tended to be less evident in group A than in the other groups. This trend continued up to the 6-week end-point when a significantly greater area reduction was found with group B (65.5%) and group C (56.8%) compared to group A (29.7%) (P <.01). Furthermore, a higher incidence of complete healing was noted with group B (20%) than with group A (4.5%) and group C (3.8%). When using a final wound reduction in excess of 40% to distinguish healing from nonhealing ulcers, it was found that only the former present NIRS StO2 values abating over the study period both at center and edge of lesions. In conclusion, NIRS analysis of StO2 and wound area can predict the healing course of VLU. Adjunctive HBOT significantly facilitates VLU healing compared to the conventional treatment alone. This positive action, however, becomes manifest only with a longer and less intensive treatment schedule.