[Effects of transcutaneous electrical acupoint stimulation combined with general anesthesia on cerebral oxygen metabolism in elderly hip replacement patients during controlled hypotension]. OBJECTIVE
 To observe the protective effect of transcutaneous electrical acupoint stimulation (TEAS) on cerebral tissue in elderly hip replacement operation patients during general anesthesia under controlled hypotension.


 Forty hip replacement operation patients were randomly divided into general anesthesia (GA) control group and TEAS + GA group (n = 20 in each group).  Patients of the two groups during operation were treated with controlled hypotension for reducing blood loss.  TEAS (2 Hz/100 Hz, 8-12 mA) was applied to bilateral Yuyao (EX-HN 4) and Fengchi (GB 20) and began 30 min before GA.  General anesthesia was performed by intravenous injection of Midazolam, Diprivan, Fentanyl and Cis-atracurium, sevoflurane-inhaling, Remifentanil, etc., and the patient's mean arterial pressure was maintained to be about 70% of the normal level (controlled hypotension) by using venous administration of Remifentanil about 10 min after the operation.  GEM Premier 3000 blood gas analyzer was used to analyze levels of the arterial oxygen (CaO2), internal jugular venous oxygen (CjvO2), arterio-venous oxygen content difference (Da-jvO2) and cerebral oxygen (CERO2) uptake rates of blood samples before controlled hypotension (T0), 20 min after controlled hypotension (T ).  40 min after controlled hypotension (T2) and 20 min after the end of controlled hypotension (T3).


 Self-comparison of each group showed that in comparison with pre-controlled hypotension, CjvO2 levels at the time-points of T, T2 and T3 were significantly increased in both GA control and TEAS+GA groups (P < 0.05), while Da-jvO2 and CERO2 uptake rate levels at the time-points of T,.  T2 and T3 in these two groups were significantly decreased (P < 0.05).  Comparison between two groups showed that CivO2 levels at the time-points of T2 and T3 were significantly higher in the TEAS + GA group than in the GA control group (P<0. 05).  while Da-jvO2 and CERO2 uptake rate levels at the time-point of T2 were obviously lower in the TEAS + GA group than in the GA control group(P<0. 05), suggesting a reduction of cerebral oxygen consumption after TEAS.  No significant differences were found between these two groups in blood CjvO2, Da-jvO2 and CERO2 uptake rate levels at the time-points of T0 and T1 (P > 0.05).


 CONCLUSION
 TEAS can reduce cerebral oxygen uptake rate in elderly patients undergoing hip replacement during controlled hypotension, suggesting a protective effect of TEAS on patient's cerebral tissue.
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