[Effect of Dexmedetomidine and Midazolam on Respiration and Circulation Functions in Patients Undergoing Open Heart Surgery under Acupuncture-Assisted General Anesthesia].

OBJECTIVE:To evaluate the effect of Dexmedetomidine and Midazolam on respiratory and circulation in patients experiencing open heart surgery under acupuncture-assisted general anesthesia. METHODS:Sixty patients undergoing open heart surgery (cardiac valve replacement surgery and aortic valve replacement surgery) were randomly and equally divided into Dexmedetomidine (D) and Midazolam (M) groups. Electroacupuncture (EA) was applied to bilateral Yunmen (LU 2), Zhongfu (LU1), Lieque (LU7) and Neiguan (PC6). For patients of group D, Dexmedetomidine (i.v., loading dose: 1 microg/kg, and succedent dose: 0.2-1 microg x kg(-1) x h(-1)) was given. For patients of group M, Midazolam (i.v., loading dose: 0.05 mg/kg, succedent dose: 0.01-0.03 mg x kg(-1) x h(-1)) was given. Arterial oxygen pressure (PaO2), arterial carbondioxide tension (PaCO2), O2 saturation (SPO2), mean arterial pressure (MAP), heart rate (HR), anesthetic effect, time of spontaneous breathing recovery, and time of resuscitation were recorded before operation (T0), immediately after skin incision (T1), immediately after sternotomy (T2), before suspension of cardiopulmonary bypass (CPB, T3), immediately after cardiac re-beating (T4), immediately after CPB cessation (T5), and at the end of surgery (T6). RESULTS:Before operation, no significant differences were found between the group D and M in the levels of PaO2, PaCO2 and SPO2 (P > 0.05). The PaO2 and SPO2 levels after skin incision, sternotomy, before suspension of CPB and at the end of surgery were significantly lower in group M than in group D (P < 0.05), while the le- vels of PaCO2 after skin incision, sternotomy, before suspension of CPB and at the end of surgery, and HR after skin incision, sternotomy, before suspension of CPB, after heart re-beating,after CPB cessation and at the end of surgery in group M were considerably higher than those in group D (P < 0.05). In addition, the time of spontaneous breathing recovery of group M was significantly later than that of group D (P < 0.05). No significant differences were found between the two groups in MAP levels at the 6 time-points during surgery, in the PaO2, PaCO2 and SPO2 levels at the time-points of post-cardiac re-beating, and after CPB cessation (P > 0.05). It suggested that the respiration and circulation states in group D were more smoothly than those in group M. There was no significant difference between the two groups in the time of resuscitation (P > 0.05). CONCLUSION:Dexmedetomidine is superior to Midazolam in analgesia, and improving respiration and circulation functions for open heart surgery patients under acupuncture-assisted general anesthesia.