Does ketamine improve the quality of sedation of intranasal dexmedetomidine premedication in children

Undergoing surgery can be a significant traumatic experience for younger children. Furthermore, preoperative crying increase the respiratory tract secretion and stress response, leading to increased heart rate (HR), blood pressure and airway hyperactivity.In order to reduce anxiety and promote the separation of parents, a variety of drugs have been advocated as premedication. Children's ideal preoperative medication should be easy to accept, fast and reliable with the minimum adverse effect. Dexmedetomidine is a selective a2 adrenergic agonist that produces analgesia as well as sedation effects via actions in the locus ceruleous without respiratory depression. Its induced sedation is similar to natural sleep, which is characterized by an easy and quick arousal. Dexmedetomidine also has some special pharmacodynamic properties, including decreased minimum alveolar concentration(MAC) and a conspicuous reduction in catecholamine secretion. Dexmedetomidine may be a suitable auxiliary medicine of ketamine, because it alleviates the cardiovascular stimulation effect of ketamine. Ketamine is the most commonly used drug for children that acts as an N-methyl-d-aspartate receptor antagonist with sedative, anesthetic, analgesic and amnesic effects and dissociation from the environment. The aim of this study was to evaluate and compare the sedative effect and safety of intranasal dexmedetomidine, intranasal ketamine and dexmedetomidine as a premedication before induction of anesthesia in pediatric tonsillectomy. Sixty children (both boys and girls) were engaged in this study, who were with ASA physical status I or II, aged between 3 and 7 years old and scheduled to undergo elective tonsillectomy. The subjects were randomly divided into two groups with thirty children each. Group Dexmedetomidine (Group D)received premedication of dexmedetomidine 2ug/kg 45 min before induction by LMA MAD. Group Dexmedetomidine + Ketamine (Group DK) received premedication of intranasal combined dexmedetomidine 2ug/kg and ketamine 2mg/kg. Sedation status was evaluated by the observer using the Modified Observer’s Assessment of Alertness/Sedation Scale (MOAA/S) at the baseline before premedication and 30 min after premedication. Patient’s response to separation from parents was assessed by the Parental Separation Anxiety Scale (PSAS), about 30 minutes after medication administration. After the patient was sent to operating room, the Patient’s Mask Acceptance Scale (MAS) score was calculated. Vital signs were continuously monitored and recorded every 15min until the child was ready to be discharged.The primary outcome of our study was the sedation score. The secondary outcomes included the separation from parents, facemask acceptance, oneset time, the time of extubation, duration of PACU stay, emergence agitation, and the incidence of adverse effects, such as nausea,vomiting. Bradycardia and hypotension (30% lower than the basic value) need to be recored during the operation.