Effect of hyperbaric oxygen on a rat transverse rectus abdominis myocutaneous flap model

The single-pedicle transverse rectus abdominis myocutaneous (TRAM) flap is frequently associated with partial flap necrosis. Hyperbaric oxygen has previously been shown to increase the survival of skin flaps, although there has been no investigation of possible beneficial effects of hyperbaric oxygen on survival of the TRAM flap. The present study compares the effectiveness of hyperbaric oxygen therapy, normobaric 100% oxygen, a hyperbaric air- equivalent mixture, and no treatment at all (control group), in the prevention of TRAM flap necrosis in a rat model. Forty-eight animals were randomly assigned to one of the four above-mentioned groups. The surviving area of the flap was evaluated 7 days after surgery. The hyperbaric oxygen treatment protocol consisted of five 9-minute sessions breathing 100% oxygen at a pressure of 2.5 atmospheres absolute during the first 48 hours, starting within 1 hour of surgery. The areas of surviving skin paddles ranged from 38.5 percent in the control group to 52.5 percent in the group treated with hyperbaric oxygen. One-way analysis of variance indicated that flap area survival was significantly greater in the hyperbaric oxygen group (F = 2.69, p = 0.05). Tukey's pairwise comparison and the two-sample t test indicated that the group treated with hyperbaric oxygen differed significantly from the control group (Tukey's critical value = 3.8, rejection level = 0.05, t test p = 0.01). Our results suggest that the hyperbaric oxygen treatment protocol used improves survival in the rat TRAM flap. However, the optimal treatment protocol to achieve this objective even in the rat seems to be variable, and further studies are required before extrapolating these data to human applications.