BACKGROUND: Dexmedetomidine has been widely used during spinal anesthesia to provide sedation. However, dexmedetomidine frequently causes significant bradycardia. This study was designed to evaluate whether fluid loading could reduce the incidence of bradycardia after intravenous dexmedetomidine infusion in patients under spinal anesthesia. METHODS: A total of 99 patients, 18 to 65 years of age, with American Society of Anesthesiologists physical status 1 or 2, who were scheduled for elective total knee replacement or internal fixation of lower leg fracture under spinal anesthesia were enrolled. The patients were randomly assigned into one of the three groups, and fluid was loaded as follows: group LOW - 4 ml/kg, group MID - 8 ml/kg, and group HI - 12 ml/kg. After fluid loading and spinal anesthesia, dexmedetomidine was infused as follows: 1 μg/kg of loading dose for 10 minutes, thereafter continuous infusion at 0.4 μg/kg/h. RESULTS: The heart rate of group HI was significantly higher than that of group LOW (P = 0.049). The dosage of atropine administration was significantly lower in group HI than in group LOW (P = 0.003). The change in thoracic fluid contents was significantly higher in group HI than in group LOW (P = 0.018). CONCLUSIONS: Fluid loading during spinal anesthesia can reduce the incidence and extent of bradycardia after intravenous dexmedetomidine infusion.
Anesthesia, Spinal* ; Arthroplasty, Replacement, Knee ; Atropine ; Bradycardia* ; Dexmedetomidine* ; Fluid Therapy ; Heart Rate ; Humans ; Incidence ; Leg

Background: Differences in the effects of propofol and dexmedetomidine sedation on electroencephalogram patterns have been reported previously. However, the reliability of the Bispectral Index (BIS) value for assessing the sedation caused by dexmedetomidine remains debatable. The purpose of this study is to evaluate the correlation between the BIS value and the Modified Observer’s Assessment of Alertness/Sedation (MOAA/S) scale in patients sedated with dexmedetomidine. Methods: Forty-two patients (age range, 20–80 years) who were scheduled for elective surgery under spinal anesthesia were enrolled in this study. Spinal anesthesia was performed using 0.5% bupivacaine, which was followed by dexmedetomidine infusion (loading dose, 0.5–1 μg/kg for 10 min; maintenance dose, 0.3–0.6 μg/kg/h). The MOAA/S score was used to evaluate the level of sedation, and the Vital Recorder program was used to collect data (vital signs and BIS values). Results: A total of 215082 MOAA/S scores and BIS data pairs were analyzed. The baseline variability of the BIS value was 7.024%, and the decrease in the BIS value was associated with a decrease in the MOAA/S score. The correlation coefficient and prediction probability between the two measurements were 0.566 (P < 0.0001) and 0.636, respectively. The mean ± standard deviation values of the BIS were 87.22 ± 7.06, 75.85 ± 9.81, and 68.29 ± 12.65 when the MOAA/S scores were 5, 3, and 1, respectively. Furthermore, the cut-off BIS values in the receiver operating characteristic analysis at MOAA/S scores of 5, 3, and 1 were 82, 79, and 73, respectively. Conclusion The BIS values were significantly correlated with the MOAA/S scores. Thus, the BIS along with the clinical sedation scale might prove useful in assessing the hypnotic depth of a patient during sedation with dexmedetomidine.

Background: Postoperative sore throat (POST) is a complication that decreases patient satisfaction and increases postoperative complaints. The present study was conducted to investigate effects of gargling with dexamethasone, intravenous dexamethasone injection and the combination of the two on the incidence and severity of POST. Methods: Study participants were 96 patients who had undergone laparoscopic cholecystectomy, randomly allocated into three groups. Group G gargled with 0.05% dexamethasone solution and were infused intravenous 0.9% normal saline before general anesthesia; group I gargled with 0.9% normal saline and were infused intravenous 0.1 mg/kg dexamethasone; group GI gargled with 0.05% dexamethasone solution and were infused intravenous 0.1 mg/kg dexamethasone. The incidence and severity of POST, hoarseness and cough were evaluated and recorded at 1, 6, and 24 h after the surgery. Results: There were no significant differences in the total incidence of POST up to 24 postoperative hours among Group G, Group I and Group GI (P = 0.367, Group G incidence = 34.38%, [95% confidence interval, 95% CI = 17.92–50.83], Group I incidence = 18.75%, [95% CI = 5.23–32.27], Group GI incidence = 28.13%, [95% CI = 12.55–43.70]). The other outcomes were comparable among the groups. Conclusions In patients who had undergone laparoscopic cholecystectomy, gargling with 0.05% dexamethasone solution demonstrated the same POST prevention effect as intravenous injection of 0.1 mg/kg dexamethasone. The incidence and severity of POST were not significantly different between the combination of gargling with 0.05% dexamethasone solution and intravenous injection of 0.1 mg/kg dexamethasone and use of each of the preventive methods alone.