Patient population Sixty patients undergoing elective gynecological laparoscopic surgery at Guizhou province people's hospital with an ASA physical status of I-II were recruited between November 2013 and November 2014. Their ages ranged from 29-60 yr. Exclusion criteria were recent use of TEAS or acupuncture, neural damage or infection along the meridian at which the acupoints lay, use of antiemetic in the previous week, regular use of opioids, hepatic dysfunction, confirmed renal impairment, diabetes mellitus, cognitive dysfunction and conversion to laparotomy during gynecologic laparoscopy.
Randomization and blinding Patients were assigned to either TEAS stimulus (TEAS group) or control group (Con group) on the basis of random numbers generated by a computer. Only the acupuncturist was informed the randomization allocation, just before the onset of TEAS. None of the anesthesiologists, surgeons, physicians in the post-anesthesia care unit (PACU), or participants were aware of the allocation. Blinding of the patients was ensured by using gel electrodes in the same therapeutic setting, which has previously been proved to be a successful strategy.
TEAS protocol An experienced acupuncturist performed TEAS for 30 min before anesthesia. According to the theory of traditional Chinese medicine, bilateral Baihui (GV20), Yingtang (EX-HN3), Zusanli (ST36) and Neiguan (PC6) were chosen as the acupuncture points. These acupoints were identified according to the traditional anatomic localization. Gel electrodes were applied to the skin after it had been cleaned with ethyl alcohol. The acupoints were then stimulated electrically with an intensity of 12-15 mA and dense-disperse frequency of 2/100 Hz for 30 min, using the Hwato electronic acupuncture treatment instrument (model No. SDZ-V, Suzhou Medical Appliances Co., Ltd, Suzhou, China). The intensity was adjusted to maintain a slight twitching of local muscles according to individual maximum tolerance, indicating a satisfactory of De-Qi phenomenon and thus adequate stimulation. The patients in the control group had the electrodes applied but received no stimulation.
Anesthesia and perioperative management One surgeon conducted all surgeries according to a standard protocol; surgery commenced between 8:30 and 1:00 p.m. Anesthesia was induced i.v. with propofol and remifentanil using a target-controlled infusion (TCI) system. After loss of consciousness, vecuronium (0.1 mg kg-1) was administered i.v., and patients were orotracheally intubed 5 min later. Anesthesia was maintained with TCI of propofol and remifentanil. The depth of anesthesia was monitored using index (BIS). Effect site concentrations of propofol and remifentanil were adjusted to the hemodynamic and BIS. Patients' lungs were mechanically ventilated in a volume-controlled mode with a tidal volume of 8ml kg-1 body weight during the operation. In both groups, remifentanil and propofol infusions were stopped 5 min before the end of surgery. Patients were extubated and transferred to the PACU after surgery.
Data collection Baseline data included demographics, body mass index (BMI), and ASA physical status. Surgical information recorded included anesthesia duration, surgery duration, estimated blood loss, and all other intraoperative medications. Postoperative data were collected regarding the incidence of nausea and vomiting, postoperative pain medications and antiemetics.
The Quality of Recovery-40 (QoR-40) is a validated scale with 5 domains 10-12. These measure physical comfort, emotional state, physical independence, psychological support, and pain. Each domain is scored to a maximum global score of 200. QoR-40 scores have been found to be associated with both quality-of-life scales and patient satisfaction indices 13 as well as postoperative pain 14. In the present study, QoR-40 evaluation was performed on preoperative day 1(T0), postoperative day 1 (T1) and postoperative day 2 (T2).
Visual analog scales (VAS) are widely used in behavioral science and previous studies reported their usefulness and validity 15, 16. VAS scores at rest queried about their level of pain on postoperative day 1 (T1) and postoperative day 2 (T2).
The Mini-Mental State Examination (MMSE) is one of the most widely used assessment instruments of cognitive functioning postoperatively, which screens domains of orientation to time and place, attention and memory, concentration, language and praxis 17. Patient cognitive function was assessed using the MMSE on preoperative day 1(T0), postoperative day 1 (T1) and postoperative day 2 (T2).
Statistical analysis All statistical analyses were performed using SPSS 13.0 (SPSS, Inc., Chicago, IL, USA). Continuous variables are presented as mean (SD) and compared using the unpaired Student's-test. Dichotomus variables were presented as the number of patients (percent) and analyzed using the X2 test. The level of significance for all statistical tests was set at 0.05.
