| Background and Objective Strabismus surgery is one of the most common ophthalmologic surgery in children,and most of bosseyed children choose to surgery before the age of six,of which at 3 years old around most general.Children of this age are more dependent on their parents and more likely to anxiety,fear and cry when separated from their parents.If coercive or bound measures taken,children will be more uncooperative,it not only has a negative impact on childrens' postoperative mentality,but also crying will increase the secretion which goes against to anesthesia induction.At this point,appropriate sedative drugs are needed,so that children can smoothly enter into the operating room and reduce their psychological trauma after surgery.Children are prone to agitated in the early recovery of pediatric general anesthesia,behavior and consciousness have a short time of separation,though the duration is short,but there are potential risks of self-injury in children,and may cause parents' fall-down.Children are covered with eyes using gauze after strabismus surgery,which may greatly increase the probability of agitation,but also increase the risk of postoperative bleeding and wound infection.Hence we should minimize the emergence agitation(EA)to ensure the postoperative recovery of children.Oculocardiac reflex(OCR)can be triggered by mechanical stimulation such as traction extraocular muscle or sudden pressure on the eye or orbital during strabismus surgery,and the heart rate may be a sharp decline,causing bradycardia or even arrhythmia.OCR is very dangerous,especially with high excitability of the vagus nerve in children,heart rate may have a more rapid decline,hence we should always be alert to the occurrence of OCR during paediatric strabismus surgery.Dexmedetomidine(Dex)is a highly selective ?2-adrenoreceptor agonist,can excite ?2A receptor of spinal cord,brain stem and hypothalamus at low-dose,leading to analgesia,sedation and anti-sympathetic,and its sedative and hypnotic effect is similar to natural sleep,easily to wake up,and no respiratory depression.Dexmedetomidine is colourless and odourless,mucosal irritation is small,and the bioavailability of absorption through the nasal mucosa is high.Intranasal dexmedetomidine has been reported to produce satisfactory sedation in children,can reduce the occurance of EA,and can be used in noninvasive diagnostic operations of children undergoing transthoracic echocardiography and magnetic resonance imaging.However,dexmedetomidine may decline the heart rate by exciting in the medulla oblongata nucleus,whether it may increase the risk of OCR and can be used safely in paediatric strabismus surgery is still unknown.And the optimal dose of intranasal dexmedetomidine in paediatric strabismus is uncertain.This study focused on the safety and efficacy of intranasal dexmedetomidine in paediatric strabismus surgery,so as to find the most suitable dose of intranasal dexmedetomidine to reduce the incidence of EA without increasing the OCR.Methods Eighty children who was undergoing elective strabismus surgery,46 males and 34 females,aged 3~6 years old,weighed 10~25 kg,ASA grade?or ?,were randomly divided into 4 groups(n=20 each): group D1,group D2,group D3 and group C.30 min before entering the operating theater,Dex was given intranasally with a dose of 1 ?g/kg,2 ?g/kg,3 ?g/kg and the same amounts of saline,respectively.If assigned to group D3,Dex was not diluted,while in group D1 and D2,Dex was diluted with normal saline to 0.03ml/kg solution.Using a 1-ml syringe to extract drug,which added to the simple nasal spray device,each press was 10?g(0.1ml).When calculating the amount of drugs,we need to add the dead space volume(about 0.1ml).After entering the operation room,routine monitoring of HR,NBP,Sp O2,and conducted intravenous anesthesia induction,3min later,the laryngeal mask was placed.we should control MAC value at 1.0 through intraoperative adjustment of sevoflurane inhalation concentration.HR and SBP were recorded at 6 time points: before administration of Dex(T0),10(T1),20(T2),30(T3)min after administration of Dex,beginning of surgery(T4)and removing laryngeal mask(T5).30 min later,the sedation score and the movement scale apart from parents were recorded.The number of extraocular muscles that were resected and the minimal heart rate during this procedure were also recorded.The EA score,PAED score,the incidence of OCR and other related complications were statisticsed.The time of removing laryngeal mask and awakening time were also included in the record.Results 1.General conditions were similar among four groups in gender,age,weight and operation time(P>0.05).2.Compared with T0,the HR and SBP at T2~T5 in group D3 were significantly decreased(P<0.05).Compared with group C and D1,the HR at T4~T5 were significantly decreased in group D2(P<0.05).When compared with the other three groups,the HR and SBP at T2~T5 in group D3 were also significantly decreased(P<0.05).3.30 min after the administration of Dex,15,55,75 and 90% patients in group C,D1,D2,D3 were satisfactorily sedated,respectively,and there were significant difference(P<0.05).The behavior score in group D3 was significantly superior to group D1 and D2(P<0.05).4.There was no statistically significant among four groups in terms of the number of extraocular muscles that were resected and diplopia(P>0.05).Compared with group C and D1,the incidence of EA in group D2 and D3 were significantly decreased,and in group D3 was significantly decreased than that in group D2(P<0.05).The incidence of OCR was no statistically significant during four groups(P>0.05).The incidence of vomiting in group D2 and D3 were significantly decreased than that in group C and D1(P<0.05).5.In terms of the time of removing laryngeal mask among four groups,there was no statistically significant(P>0.05).Compared with group D1 and D2,the awakening time was significantly longer in group D3(P<0.05).Conclusion Preoperative intranasal dexmedetomidine in a dose of 2?g/kg and 3?g/kg,the sedative state was significantly improved,it can achieve safe separation from parents,and significantly decrease the incidence of EA without increasing the occurrence rate of OCR.Intranasal dexmedetomidine in a dose of 3?g/kg can significantly prolong the awakening time,2?g/kg intranasal dose is more suitable for pediatric strabismus surgery. |
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