CLINICAL EVALUATION OF DEXMEDETOMIDINE-MIDAZOLAMKETAMINE WITH ATRACURIUM FOR ISOFLURANE ANAESTHESIA IN DOGS
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Date
2018-01-11
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Abstract
8. ABSTRACT
General anaesthesia with sustained muscle relaxation is inevitable for most
of the surgical procedures performed. Additional muscle relaxation, without
deepening anaesthesia, could be attained by administering a peripheral acting
muscle relaxant like atracurium. Accordingly the study was conducted to find out
the clinico-physiological and haemodynamic effects of atracurium on animals
induced with dexmedetomidine-midazolam-ketamine combination and maintained
on isoflurane for various surgical procedures. The study was conducted in twelve
dogs which underwent various surgical procedures, in the Department of Veterinary
Surgery and Radiology, College of Veterinary and Animal Sciences, Pookode,
Wayanad. These dogs were randomly allocated into two groups – Group I and
Group II, of six animals each. Animals of Group I were anaesthetised with a drug
combination of dexmedetomidine, midazolam and ketamine at the rate of 5 μg/kg,
0.2 mg/kg and 5 mg/kg body weight respectively as a single intramuscular injection.
Following endotracheal intubation, isoflurane was administered in oxygen to
maintain anaesthesia. In Group II, following induction with the same injectable
drug combination and maintenance with isoflurane, a loading dose of atracurium at
the dose rate of 0.1 mg/kg body weight was administered intravenously,
immediately followed by a continuous rate infusion of atracurium at a dose rate of
0.1 mg/kg/hour.
The quality of anaesthetic induction, produced by the dexmedetomidinemidazolam-
ketamine combination was excellent in all the animals. There was
profound sedation in all the twelve animals following the intramuscular
administration of the injectable anaesthetic combination, and the transition to
anaesthesia was calm and smooth. Eyeball rolled ventrally and medially. There was
profound relaxation of jaw muscle and laryngeal tone which permitted easy
intubation.
Respiratory rate reduced in all the animals following induction with the
injectable anaesthetic combination. Administration of atracurium in the animals of
Group II produced pronounced reduction in the rate and depth of respiration which
necessitated manual assisted ventilation for every spontaneous breath.
All four muscle twitches were present in the animals of Group I, after
induction and during maintenance of anaesthesia. But the twitches, assessed
visually, were not as strong as those before administration of the injectable
anaesthetic drug combination. The eye ball was positioned ventrally and medially
in all the animals of Group I, after induction and during maintenance. There was
disappearance of two muscle twitches and central positioning of the eyeballs within
five to eight minutes after administration of atracurium. The eyeballs maintained
the central position and the third and fourth muscle twitches remained absent up to
20th minute, after which the eyeballs rolled down and the twitches reappeared and
remained so throughout the period of anaesthesia.
There were no significant variations in the haematological, serum
biochemical, blood gas and electrolyte values in both the groups.
Time taken for recovery, time to regain sternal recumbency and time to
assume standing posture unassisted, following weaning from anaesthesia did not
vary significantly in the animals administered with atracurium when compared to
the animals of Group I.
It could be thus concluded that dogs anaesthetised with intramuscular
injection of dexmedetomidine-midazolam-ketamine combination and maintained
on isoflurane when administered atracurium intravenously followed immediately
by a continuous rate infusion, provided profound muscle relaxation without
compromising the haemodynamic functions, but the marked reduction in the rate
and depth of respiration necessitated assisted ventilation.
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