OBJECTIVETo Evaluate the effects of different oxygen therapies on the rats with acute nitrogen asphyxia and to study the best oxygen therapic protocol for patients with acute nitrogen asphyxia on the spot.

METHODSSixty healthy male Wistar rats were divided into 5 groups: control, exposure to nitrogen, 33% oxygen treatment, 50% oxygen treatment and hyperbaric oxygen treatment groups. The behavioral performance, arterial oxygen pressure (PO2), carbon dioxide partial pressure (PCO2) and oxygen saturation (SPO2), biochemical changes in liver and kidney function and myocardial enzymes in 5 groups were measured.

RESULTSThe rats exposed to nitrogen firstly were excited then inactive symptoms, but consciousness was recovered after oxygen therapy. The PO2 and SPO2 in nitrogen exposure group were (79.67 +/- 9.12) and (94.92 +/- 2.78) mm Hg, respectively, which were significantly lower than those in control group (P<0.01). The PO2 and SPO2 of 3 oxygen treatment groups were (94.75 +/- 7.24), (94.92 +/- 8.98), (104.58 +/- 7.12)mm Hg and (97.17 +/- 0.83), (96.92 +/- 1.16), (97.42 +/- 0.67)mm Hg, respectively, which were significantly higher than those in nitrogen exposure group (P<0.05). The PO2 in hyperbaric oxygen treatment group was significantly higher than those in other 2 oxygen treatment groups (P<0.05). The SPO2 in hyperbaric oxygen treatment group was (51.42 +/- 6.60) mm Hg which was significantly higher than that [(44.58 +/- 3.42)mm Hg] in 50% oxygen treatment groups (P< 0.05). AST [(270.50 +/- 49.05 )U/L], ALT [(122.67 +/- 55.44 )U/L], BUN [(7.31 +/- 0.93 )mmol/L], Cr[(28.32 +/- 4.35) micromol/L], CK [(1808.42 +/- 582.05)U/L] and CtnI [(22.52 +/- 14.29 )ng/ml] in nitrogen exposure group were significantly higher than those in control group (P<0.05). AST [(165.25 +/- 30.87) U/L], HBDH [(350.83 +/- 103.00)U/L] and CtnI [(11.23 +/- 5.38) ng/ml] in hyperbaric oxygen treatment group were significantly lower than those in other 2 oxygen treatment groups (P<0.05).

CONCLUSIONTimely and effective oxygen therapy can significantly increase arterial pressure of oxygen and oxygen saturation in the rats with acute nitrogen asphyxia, and can improve liver function and cardiac damage. The hyperbaric oxygen chamber can significantly increase the therapeutic effects on rats with acute nitrogen asphyxiation.