Premium
Medetomidine‐ketamine anaesthesia induction followed by medetomidine‐propofol in ponies: infusion rates and cardiopulmonary side effects
Author(s) -
BETTSCHARTWOLFENSBERGER R.,
BOWEN I. M.,
FREEMAN S. L.,
WELLER R.,
CLARKE K. W.
Publication year - 2003
Publication title -
equine veterinary journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.82
H-Index - 87
eISSN - 2042-3306
pISSN - 0425-1644
DOI - 10.2746/042516403776148354
Subject(s) - medetomidine , anesthesia , propofol , ketamine , medicine , heart rate , respiratory rate , sedation , ventilation (architecture) , general anaesthesia , blood pressure , mechanical engineering , engineering
Summary Reasons for performing study : To search for long‐term total i.v. anaesthesia techniques as a potential alternative to inhalation anaesthesia. Objectives : To determine cardiopulmonary effects and anaesthesia quality of medetomidine‐ketamine anaesthesia induction followed by 4 h of medetomidine‐propofol anaesthesia in 6 ponies. Methods : Sedation consisted of 7 μg/kg bwt medetomidine i.v. followed after 10 min by 2 mg/kg bwt i.v. ketamine. Anaesthesia was maintained for 4 h with 3.5 μg/kg bwt/h medetomidine and propofol at minimum infusion dose rates determined by application of supramaximal electrical pain stimuli. Ventilation was spontaneous (F I O 2 > 0.9). Cardiopulmonary measurements were always taken before electrical stimulation, 15 mins after anaesthesia induction and at 25 min intervals. Results : Anaesthesia induction was excellent and movements after pain stimuli were subsequently gentle. Mean propofol infusion rates were 0.89–0.1 mg/kg bwt/min. No changes in cardiopulmonary variables occured over time. Range of mean values recorded was: respiratory rate 13.0–15.8 breaths/min; PaO 2 29.1–37.9 kPa; PaCO 2 6.2–6.9 kPa; heart rate 31.2–40.8 beats/min; mean arterial pressure 90.0–120.8 mmHg; cardiac index 44.1–59.8 ml/kg bwt/min; mean pulmonary arterial pressure 11.8–16.4 mmHg. Recovery to standing was an average of 31.1 mins and ponies stood within one or 2 attempts. Conclusions : In this paper, ketamine anaesthesia induction avoided the problems encountered previously with propofol. Cardiovascular function was remarkably stable. Hypoxaemia did not occurbut, despite F I O 2 of >0.9, minimal PaO 2 in one pony after 4 h anaesthesia was 8.5 kPa. Potential relevance : The described regime might offer a good, practicable alternative to inhalation anaesthesia and has potential for reducing the fatality rate in horses.