CARDIOPULMONARY AND STRESS RESPONSE TO LOW FLOW ISOFLURANE ANAESTHESIA WITH OPIOID ANALGESICS IN CATTLE
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Date
2013
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Publisher
TANUVAS, Chennai
Abstract
The study was conducted in 30 clinical cases of cattle presented to
Department of Veterinary Surgery and Radiology for surgical interventions
under general anaesthesia during March 2011 to March 2013. The animals
were randomly divided into three equal groups viz., group I, II and III.
In all the animals, acepromazine maleate was administered at the dose
rate of 0.04mg per kg body weight intravenously. In group II and III,
butorphanol tartrate and buprenorphine hydrochloride were administered
intravenously at the dose rate of 0.02 and 0.06 mg per kg body weight,
respectively. Guaifenesin as a 5 per cent solution in 5 per cent dextrose
normal saline was administered at the dose rate of 50 mg per kg and
anaesthesia was induced with administration of ketamine hydrochloride at the
dose rate of 4 mg per kg body weight. Endotracheal intubation was
accomplished in all the animals with cuffed Murphy type endotracheal tube to
provide a secure leak-free airway. Maintenance of anaesthesia was carried
out with isoflurane employing large animal anaesthetic machine with
ventilator.
The built-in manometer on the expiratory limb of the anaesthetic circle
was used to record the changes in airway pressure during spontaneous
ventilation. The positive end-expiratory pressure (PEEP) caused by the
weight of the ascending bellows of the ventilator was recorded during
maintenance of anaesthesia at 10 min interval. The oxygen flow was set at 10
litres per minute for the first 3 min to attain denitrogenation of the anaesthetic
circle and also to increase the fraction of inspired-oxygen concentration. The
fresh gas flow rate was then reduced to 3 to 5 litres based on the size of the
animal. The changes made on the fresh gas flow rate and vapourizer setting
at various times during maintenance of anaesthesia was recorded. The
quantity of isoflurane utilized for maintenance of anaesthesia was calculated
by Avogadro’s principle. The fraction of inspired oxygen, carbon dioxide and
isoflurane concentration and end-tidal oxygen, carbon dioxide and isoflurane
concentration were recorded using multigas monitor during low flow isoflurane
anaesthesia.
The tidal volume in group II was significantly lower (p<0.01) as
compared to that of group I and III. The compensatory increase in respiratory
rate maintained the minute volume during anaesthesia in group II animals.
The minute volume in group III was significantly lower (p<0.01) as compared
to that of group I and II indicating that the ventilation was depressed, as also
observed from the elevated levels of end-tidal carbon dioxide concentration in
group III.
The fraction of inspired-oxygen concentration in group I was
significantly higher (p<0.01) as compared to that of group II and III and this
could be due to the increased fresh gas flow rate employed during
maintenance of anaesthesia. The end-tidal concentration of isoflurane
required to maintain anaesthesia was significantly lower in group II as
compared to that of group I and III.
The extubation time in group II and III was comparatively longer
(p<0.05) than group I due to the inclusion of opioids which depressed the
cough and swallowing reflex resulting in delayed extubation. Isoflurane
utilization in group II and group III were significantly lower (p<0.05) as
compared to that of group I indicating that opioids used in the study had
isoflurane sparing effect. In the present study, untoward events or
complications were not encountered in any of the animals indicating that the
anaesthetic protocol employed was safe and effective. The serum cortisol
estimation revealed that stress response was lower (p<0.05) in group II which
could be due to the better analgesia provided by butorphanol tartrate during
surgery.
Description
TNV_THE_Y2013_DPV(N)10014
Keywords
Veterinary Science, Veterinary Surgery and Radiology