Abstract: Methods: Forty-three patients, who had off-pump coronary artery bypass graft (CABG) surgery, were randomly divided into two groups, control group(n=22) and experimental group(n=21). patients in both group accepted routine treatment. The experimental group was given the treatment of dexmedetomidine additionally. SaO2,HR,BP,RR,PaCO2、PaO2 were observed pre-treatment and 30min,6 hours after treatment. Duration of ICU stay and endotracheal re-intubation were also observed. Results: The differences between two groups were not significantly initially. Compared with control group，SaO2, PaCO2、PaO2 improved, while the Hr and RR decreased after the therapy of dexmedetomidine 30min and 6 hours later. There were no changes of PaCO2. The incidence of endotracheal re-intubation was lower than the control group(P＜0.05). And the duration of ICU stay of experimental group was much shorter than the control group. The difference between the two groups was statistically significant(p＜0.05) . Conclusion：Dexmedetomidine combined with routine treatment in postoperative hypoxemia after off-pump CABG could correct hypoxemia，And it could decrease incidence of endotracheal re-intubation and shorten duration of ICU stay.

Key words: Dexmedetomidine, coronary artery bypass graft, postoperative hypoxemia