The clinical
analgesic effect of electro-acupuncture (EA) stimulation (EAS) on
breakthrough pain induced by
remifentanil in patients undergoing radical thoracic
esophagectomy, and the mechanisms were assessed. Sixty patients (ASAIII) scheduled for elective radical
esophagectomy were randomized into three groups: group A (control) receiving a
general anesthesia only; group B (
sham) given EA needles at PC4 (Ximen) and
PC6 (Neiguan) but no stimulation; and group C (EAS) electrically given EAS of the ipsilateral PC4 and
PC6 throughout the surgery. The EAS consisting of a disperse-dense wave with a low frequency of 2 Hz and a high frequency of 20 Hz, was performed 30 min prior to induction of
general anesthesia and continued through the surgery. At the emergence,
sufentanil infusion was given for postoperative
analgesia with loading dose of 7.5 μg, followed by a continuous infusion of 2.25 μg/h. The patient
self-administration of
sufentanil was 0.75 μg with a lockout of 15 min as needed. Additional
breakthrough pain was treated with
dezocine (5 mg) intravenously at the patient's request. Blood samples were collected before (T1), 2 h (T2), 24 h (T3), and 48 h (T4) after operation to measure the plasma β-EP,
PGE2, and
5-HT. The
operative time, the total dose of
sufentanil and the dose of
self-administration, and the rescue doses of
dezocine were recorded. Visual Analogue Scale (VAS) scores at 2, 12, 24 and 48 h postoperatively and the incidence of
apnea and severe
hypotension were recorded. The results showed that the gender, age, weight,
operative time and
remifentanil consumption were comparable among 3 groups. Patients in EAS group had the lowest VAS scores postoperatively among the three groups (P<0.05). The total dose of
sufentanil was 115±6.0 μg in EAS group, significantly lower than that in control (134.3±5.9 μg) and
sham (133.5±7.0 μg) groups. Similarly, the rescue dose of
dezocine was the least in EAS group (P<0.05) among the three groups. Plasma β-EP levels in EAS group at T3 (176.90±45.73) and T4 (162.96±35.00 pg/mL) were significantly higher than those in control (132.33±36.75 and 128.79±41.24 pg/mL) and
sham (136.56±45.80 and 129.85±36.14 pg/mL) groups, P<0.05 for all. EAS could decrease the release of
PGE2. Plasma
PGE2 levels in EAS group at T2 and T3 (41±5 and 40±5 pg/mL respectively) were significantly lower than those in control (64±5 and 62±7 pg/mL) and
sham (66±6 and 62±6 pg/mL) groups. Plasma
5-HT levels in EAS group at T2 (133.66±40.85) and T3 (154.66±52.49 ng/mL) were significantly lower than those in control (168.33±56.94 and 225.28±82.03) and
sham (164.54±47.53 and 217.74±76.45 ng/mL) groups. For intra-group comparison, plasma
5-HT and
PGE2 levels in control and
sham groups at T2 and T3, and β-EP in EAS group at T3 and T4 were significantly higher than those at T1 (P<0.05);
PGE2 and
5-HT levels in EAS group showed no significant difference among the different time points (P>0.05). No
apnea or severe
hypotension was observed in any group. It was concluded that intraoperative ipsilateral EAS at PC4 and
PC6 provides effective postoperative
analgesia for patients undergoing radical
esophagectomy with
remifentanil anesthesia and significantly decrease requirement for parental
narcotics. The underlying mechanism may be related to stimulation of the release of endogenous β-EP and inhibition of inflammatory mediators (5-HT and
PGE2).