A total of 179 patients who received laparoscopic surgery in The First People's Hospital of Wujiang District (Suzhou, China) from March 2015 to May 2017 were selected and randomly divided into the control group and three groups with different doses of dexmedetomidine. Among them, the control group (group A) included 42 patients aged 23–43 years, with an average age of 34.4±7.3 years; the low-dose group (group B) included 47 patients, aged 22–44 years, with a mean age of 35.4±6.8 years; the middle-dose group (group C) had 45 patients, aged 22–45 years, with a mean age of 34.9±6.4 years; and the high-dose group (group D) had 45 patients, aged 23–44 years, with a mean age of 36.9±6.8 years. There were no significant differences in age and pathogenetic condition of the patients among the four groups (p>0.05), and the data were comparable. All patients were aware of the clinical protocol before the study and signed the informed consent. This study was approved by the Ethics Committee of The First People's Hospital of Wujiang District (Suzhou, China). Inclusion criteria were: female patients aged 20–45 years and rated as class 1 based on the America society of Anesthesiologist (ASA) classification. Exclusion criteria were: patients with mental disease or with injury in the heart, liver, kidney and other vital organs.

The four groups of patients received anesthesia induction, in which, the medication dosages were 0.6 mg·kg⁻¹, 2 mg·kg⁻¹ and 2 µg·kg⁻¹ for rocuronium bromide, propofol and fentanyl, respectively, and tracheal intubation was also performed. Patients in groups B, C and D were given 0.25, 0.5 and 1 µg/kg dexmedetomidine, respectively, while those in group A were administered with the same dose of 0.9% NaCl solution. Patients in each group received intravenous infusion for 10 min. After incubation, mechanical ventilation was carried out with tidal volume set at 8 ml/kg and respiratory rate at 8 breaths per minute. During surgery, doses of propofol and fentanyl were adjusted according to the patient's condition. When the endoscope was withdrawn, medication was stopped immediately.

The operation duration, intraoperative bleeding volume and intraoperative transfusion volume of each patient were recorded. Serum inflammatory cytokines [C-reactive protein (CRP), tumor necrosis factor-α (TNF-α) and interleukin-10 (IL-10)] of patients were detected. Visual analogue scale (VAS) scoring. Agitation scoring and Sedation scoring were also recorded for each patient (6–10).

SPSS 19.0 software (IBM, Armonk, NY, USA) was used for statistical analysis. All quantitative data were expressed as mean ± standard deviation (SD). Comparison between groups was done using one-way ANOVA test followed by post hoc test (Least Significant Difference). P-values <0.05 were considered statistically significant.

The operation duration, intraoperative bleeding volume and intraoperative transfusion volume of the four groups of patients showed no differences (p>0.05) (Table I).

It was found that the VAS scores at all time-points in the control group were significantly higher than those in the other three treatment groups after operation, and the scores in group D were the lowest (Table II).

In comparison with group A, group C had obviously decreased agitation score and sedation score (p<0.05); there were no evident differences in agitation score and sedation score between groups A and B; sedation score in group D was clearly higher than that in group C (Table III).

The levels of CRP, TNF-α and IL-10 in groups A, B and C were significantly increased at T2, T3 and T4, while the levels of IL-10 at T2, T3 and T4 in group D were overtly higher than that at T1 (p<0.05), while the levels of inflammatory cytokines in groups A and B had no significant differences. In addition, the levels of CRP and TNF-α in patients in groups A and B were clearly higher than those in groups C and D, while the increases in levels of IL-10 in groups C and D were significantly higher than those in the first two groups (p<0.05) (Table IV).

Adverse reactions of patients in the four groups were compared, and it was found that group C had significantly fewer cases in tachycardia, bradycardia and hypertension compared with those in groups A and B. Finally, patients in group D had symptoms of bradycardia and hypotension, and sometimes hypertension and delayed recovery (Table V).