Synergistic effect of hyperbaric oxygen preconditioning and hydrogen-rich saline in ameliorating rat flap ischemia/reperfusion injury

Aim: This study was conducted to evaluate the synergistic effects of hyperbaric oxygen (HBO) preconditioning and hydrogen-rich saline (HRS) treatment on skin flap survival and apoptosis in a rat ischemia/reperfusion (IR) skin flap model. Methods: Male Sprague-Dawley rats were randomly divided into five groups: one sham surgery group (sham group) and four surgery groups (IR group, HBO group, HRS group, and HBO + HRS group). An extended epigastric adipocutaneous flap (6 cm × 9 cm) was raised over the abdomen in each animal of all five groups. The last four groups underwent 6 h of IR management and were treated, respectively, with normal saline, HBO, HRS (HRS, 0.8 mmol/L), or a combined approach (HBO and HRS). On the 3rd postoperative day, flap survival rate and perfusion condition, apoptotic index, caspase-3 activity, protein expression of pASK1 and Bcl-2/Bax ratio, and Bcl-2 messenger RNA (mRNA) expression were assessed. Results: Prior studies have shown the protective effects of HBO and HRS, both of which have been associated with an increase in flap survival. Compared to the IR group, the flaps in the HBO, HRS, and HBO + HRS groups showed better perfusion and a larger survival area with a low number of apoptotic cells, low caspase-3 activity and pASK1 expression, and a high Bcl-2/Bax ratio and Bcl-2 mRNA expression. Of these groups, the HBO + HRS group showed the best flap survival. Conclusion: Both HBO and HRS treatments increase the rate of flap survival, while the synergistic application of HBO and HRS showed a higher survival rate as compared to individual treatments of each. The potential regulation of apoptosis with the use of these two modalities may improve skin flap survival.