Short Hyperbaric Oxygen Treatment Improves Bone Healing in Rats

Objectives: Rat's blood oxygen partial pressure is about twice that in the humans, and the healing of wounds is rapid. Nevertheless, in rat experiments with hyperbaric oxygen (HBO), protocols for humans have commonly been applied. We tested if, for improving bone healing in rat's mandible, the duration of HBO treatment could be shortened by using higher pressure than in human HBO therapy. Methods: In groups of fifteen, sixty 250g male Wistar rats received HBO or placebo (PLO) treatment as follows: Group HBO10 for ten days at 3.0 ATA, 60 minutes each day. Group HBO20, according to human protocol, for twenty days at 2.4 ATA, 90 minutes each day. Ten (PLO10) and 20 day (PLO20) control groups didn't get HBO. All rats received a 1.5 mm hole in the inferior margin of the mandible, three (10 day rats) or seven (20 day rats) days, after starting HBO. After sacrifice the healing holes were exposed and measured using a stereo microscope (Leica MZ6, Heerbrugg, Switzerland), camera (Leica DC 200), and computer software (Leica IM500 Image Manager). Results: Healing in HBO10 rats was significantly better than that of PLO10 (t-test: P = 0.002). Also, in HBO20 rats it was better than in PLO10 (t –test: P < 0.001), or PLO20 (t-test: P = 0.031). Between HBO10 and HBO20, or PLO10 and PLO20 no significant differences were found, although the difference between PLO 10 and PLO20 was suggestive (P = 0.06). Conclusions: This study indicates that short HBO treatment improves the healing of bone wounds in rats. As an advantage, with short protocol, rats' normally fast healing does not as much catch up with the HBO accelerated healing as in long protocols. This work was supported by the Kuwait University Research Administration Grant No. DR 02/02.