| Objective: To study the effects of a single dose of dexmedetomidine, on sevofluraneinduced postanesthesia during the period of tracheal extubation in children undergoing Tonsillectomy.Methods: One hundred and twenty healthy children, ASA class ⅠorⅡ,aged 3-8 years old,scheduled for Tonsillectomy were enrolled. Exclusion criteria were known allergy to a2 agonists, developmental delay, cardiac and craniofacial abnormalities, anxiety disorder, chronic disabilities or pain syndrome, and use of psychotherapeuticmedications, b-blockers, digoxin, cimetidine,a2 agonists, anticonvulsants, or psychotropic medications. The patients were randomly assigned to receive saline(group NS, n=30), dexmedetomidine 0.2 ug/kg(group DL, n=30),dexmedetomidine 0.4 ug/kg(group DM, n=30),dexmedetomidine 0.6ug/kg(group DH, n=30),10 minutes before the end of surgery, lntraoperativc hemodynamics were recorded in every 5 min. Monitoring included pulse oximetry, electrocardiogram, noninvasive arterial blood pressure(NIBP), end-tidal CO2(etco2), and Bispectral Index(BIS; Aspect Medical Systems). Anesthesia was induced with IV dexamethason 0.5ug/kg,IV Propofol 2.0 mg/kg, IV fentanyl 1ug/kg and Cisatracurium 0.15 mg/kg was given for muscle relaxation. The anaesthetic gas concentrations were adjusted to maintain adequate anaesthesia and stable haemodynamics and BIS was maintained between 40 and 50 during the surgery. Ventilation was controlled to maintain an end-tidal CO2 of 35 to 40 mm Hg. Anesthesia was maintained with 1.5–2.5% sevoflurane(Abbott Laboratories S.A. Abbott Park, IL, USA), fresh oxygen gas flow of 2.0 L/min 0.5–1 mg kg-1min-1 Remifentanil was continuous infused and controlled by a micropump. At the end of surgery, the anaesthetic ahents were discontinued. Any residual neuromuscular blockade, as determined by train-of-four monitoring, was reversed with 50 μg.kg-1 neostigmine and 20 μg.kg-1 atropine, and the children were allowed to breathe spontaneously. After return of sufficient spontaneous ventilation(VT >5 ml.kg-1, respiratory rate >12 breath.min-1) and gag reflex, the tracheal tube was removed and the patients were transferred to the recovery room. At the end of anesthesia, the incidence of emergence agitation was recorded. The following time intervals were recorded: The duration of surgery(from the time of mouth opening to the completion of the procedure), duration of sevoflurane anesthesia(from mask induction to the discontinuation of the inhaled anesthetic), duration of extubation(from the discontinuation of sevoflurane to the removal of endotracheal tube), time of emergence(from discontinuation of sevoflurane to the first response to a simple verbal command), and duration of PACU stay(from arrival to the PACU until discharge). Children were discharged from the PACU to a ward when the modified aldrete score was more than nine without agitation and vomiting. Observers in the postanesthesia care unit(PACU) were blinded to treatment groups. Pain was evaluated using the modify-Children’s in the PACU on arrival, at 5 minute, at 10 minute, at 25 minute and at 40 minute. Emergence agitation was evaluated at the same intervals by the Pediatric Anesthesia Emergence Delirium scale. Severe pain(score ≥4) with or without severe agitation(score ≥4) was treated with intravenous fentanyl(1 μg.kg-1) According to a power analysis, a sample size of 30 patients per group would have an 80% power to detect a reduction in the incidence of agitation at a significance level of 5%. Statistical analyses of the study were performed using SPSS for Windows, version 19.0(SPSS Inc.). Data were compared among the groups using one-way analysis of variance followed by a post-hoc testing Bonferroni or Kruskal- Wallis test as appropiate. Haemodynamic variables within group were analysed using repeated-measures analysis of variance and then Bonferroni correction. The incidence of side-effects were analysed by the chi-square test. A P value of <0.05 was considered to be statistically significant.Results:1 There was no significant differences in the index of general date and duration of operation.2 Compared with group NS, HR and SBP were significantly decreased at T3-6 in group DL, DM and DH. Compared with group T0, HR was significantly decreased at T4-6 and SBP was significantly decreased at T5-6 in group DH.3 Compared with group NS, eye-opening time was significantly increased in group DM and group DH. Compared with group NS, extubation time was significantly increased in group DH.4 Compared with group NS, the incidence of PAED points >15 was significantly decreased at TP5, TP10 and TP25 in group DH and group DM.5 Compared with group NS, the incidence of m-CHEOPS points >10 was significantly decreased at TP0 in group DH and group DM., and there ware significantly decreased at TP5 in each group.Conclusion:A single dose of dexmedetomidine 0.4ug/kg combined with inhalation anesthetics provided satisfactory intraoperative conditions for tonsillectomy without adverse hemodynamic effects. Postoperative opioid requirements were significantly reduced, and the incidence and duration of severe emergence agitation was lower compare with patients who were administrated with saline. However, caution should be taken in regard to bradycardia and hypotension... |
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