Effect Of Different Induction Methods On Isoflurane Anaesthesia And ECG In Dogs

Adminstration of single drug anaesthesia in veterinary clinic,often have more side effects,and may not be able to achieve the desired effect of anaesthesia.We usually used propofol or etomidate to induce anaesthesia,and isoflurane maintenance anaesthesia.Dexmedetomidine is commonly used as a premedication in dogs.Emulsified isoflurane,an intravenous injection be made of isoflurane.These drugs have different side effects on the physiological function and cardiovascular system when use either alone in dogs.The purpose of this study was to investigate the respective effects of these drugs alone and in combination with dexmedetomidine on the cardiopulmonary system and electrocardiogram,and also to provide experimental evidence for these drugs adminstration in veterinary clinic.1.Physiological parameters and ECG in dogs following several induction methods and isoflurane maintenance anaesthesia5 dogs received each of 5 treatments,with at least 2 weeks between treatments.Mask(group M);propofol(group P);etomidate(group E);thiopental(group T);and 8%emulsified Isoflurane(group EI).The dogs underwent tracheal intubation after induced anaesthesia,followed by 1.5 MAC of isoflurane to maintain anaesthesia.The physiological parameters and ECG were monitored.The results showed that inhalation induction of anaesthesia using isoflurane has a long induction time,struggling,and less effect on cardiovascular system.Propofol provided good conditions for induction of anaesthesia.The R-wave amplitude,and T-wave amplitude and duration increased in group P.The quality of induction and recovery in group E was worse than other groups.After thiopental administrated,there were delayed recovery,sinus tachycardia,and the duration of P-R interval decreased.Emulsified isoflurane showed a good quality of induction and has no significant effects on the cardiovascular system.2.Physiological parameters and ECG in dogs following induction using several anaesthetic in combination with dexmedetomidine,and isoflurane maintenance anaesthesia5 dogs received each of 4 treatments,with at least 2 weeks between treatments.group DP(dexmedetomidine 3 ?g/kg,propofol 4 mg/kg,IV);group DE(dexmedetomidine 3 ?g/kg,etomidate 2 mg/kg,?);group DT(dexmedetomidine ?g/kg,thiopental 10 mg/kg,IV)and group DEI(dexmedetomidine 3 ?g/kg,emulsified isoflurane 0.5 mL/kg,IV).The dogs underwent tracheal intubation after induced anaesthesia,followed by 1.5 MAC of isoflurane to maintain anaesthesia.The physiological parameters and ECG were monitored.The results showed that all the anaesthetic procedures provided good conditions for induction of anaesthesia.The inhibition of respiration in group DEI was less than other groups.Four kinds of induction methods caused blood pressure decrease 40%.DP group showed sinus heart rate,and T-wave amplitude increased.There were I degree atrioventricular block and T-wave amplitude increased in DE group.The S-T segment was deviation,and sinus arrhythmia in DT group.We observed slightly sinus arrhythmia and T-wave amplitude increased in DEI group.Combined administration of dexmedetomidine reduced the side effects of use either alone.3.Physiological parameters and ECG in dogs following induction using propofol or etomidate,and emulsified isoflurane maintenance anaesthesia5 dogs received each of 3 treatments,with at least 2 weeks between treatments.propofol(group P);etomidate(group E);emulsified isoflurane(group EI).The dogs underwent tracheal intubation after induced anaesthesia,followed by 8%emulsified isoflurane(8 mL/kg/h)to maintain anaesthesia.The physiological indicators and ECG were monitored.The results showed that all the three induction methods provided good conditions for induction of anaesthesia.Propofol administration resulted in the RT,MAP and HR decreased.We observed obvious respiratory depression and significant changes of MAP in the El group.SpO2 was lower to about 90%in all groups during emulsified isoflurane maintenance anaesthesia.The P-wave and T-wave increased in P group,but the difference was not significant.The E group demonstrated significant extension of the S-T segment and T-wave asymmetry.The S-T segment was deviation and extension in the El group.In conclusion:In combination of dexmedetomidine with several drugs increased the induction quality of anaesthesia,reduced the anaesthetic use either alone and the side effects on the ECG.Combined anesthesia may be useful in the veterinary clinic.