Anesthetic and cardiovascular effects of balanced anesthesia using constant rate infusion of midazolam-ketamine-medetomidine with inhalation of oxygen-sevoflurane (MKM-OS anesthesia) in horses.
ABSTRACT The anesthetic sparring and cardiovascular effects produced by midazolam 0.8 mg/ml-ketamine 40 mg/ml-medetomidine 0.05 mg/ml (0.025 ml/kg/hr) drug infusion during sevoflurane in oxygen (MKM-OS) anesthesia was determined in healthy horses. The anesthetic sparring effects of MKM-OS were assessed in 6 healthy thoroughbred horses in which the right carotid artery was surgically relocated to a subcutaneous position. All horses were intubated and ventilated with oxygen using intermittent positive pressure ventilation (IPPV). The end-tidal concentration of sevoflurane (ET(SEV)) required to maintain surgical anesthesia was approximately 1.7%. Heart rate and mean arterial blood pressure averaged 23-41 beats/min and 70-112 mmHg, respectively. All horses stood between 23-44 min after the cessation of all anesthetic drugs. The cardiovascular effects of MKM-OS anesthesia were evaluated in 5 healthy thoroughbred horses ventilated using IPPV. Anesthesia was maintained for 4 hr at an ET(SEV) of 1.7%. Each horse was studied during left lateral (LR) and dorsal recumbency (DR) with a minimum interval between evaluations of 1 month. Cardiac output and cardiac index were maintained between 70-80% of baseline values during LR and 65-70% of baseline values during DR. Stroke volume was maintained between 75-85% of baseline values during LR and 60-70% of baseline values during DR. Systemic vascular resistance was not different from baseline values regardless of position. MKM-OS anesthesia may be useful for prolonged equine surgery because of its minimal cardiovascular depression in both of lateral and dorsal recumbency.
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ABSTRACT: Objective To review the literature with regard to the use of different intravenous agents as supplements to inhalational anaesthesia in horses. These drugs include lidocaine, ketamine, opioids and α2-agonists. The Part 1 of this review will focus in the use of lidocaine and ketamine.Databases usedPubmed & Web of Science. Search terms: horse, inhalant anaesthesia, balanced anaesthesia, partial intravenous anaesthesia, lidocaine, ketamine.Conclusions Different drugs and their combinations can be administered systemically in anaesthetized horses, with the aim of reducing the amount of the volatile agent whilst improving the recovery qualities and providing a multimodal analgesic approach. However, full studies as to whether these techniques improve cardiopulmonary status are not always available and potential disadvantages should also be considered.Veterinary Anaesthesia and Analgesia 05/2014; · 1.34 Impact Factor
Article: Balanced Anesthesia in the Equine[Show abstract] [Hide abstract]
ABSTRACT: The following article aims at giving an overview on currently available balanced anesthetic regimens for horses. In horses, maintenance of cardiovascular function and thus muscular perfusion during anesthesia is essential. Also, a smooth recovery phase which should be completed within at least 1 hour of termination of drug administration is crucial. All inhalation anesthetics depress cardiovascular function dose dependently. Thus, drugs that decrease the need for inhalation anesthetics (decrease MAC) might improve cardiovascular function during anesthesia. Lidocaine constant rate infusion (CRI), at clinically used dose rates, decreases MAC by about 25%, and no untoward cardiovascular side effects have been reported. In horses anesthetized for several hours, careful dosing is advised. Toxicity due to accumulation, masked during anesthesia, might become apparent during recovery. Ketamine is the only drug used for balanced anesthesia that might positively influence cardiovascular function. But following continuous ketamine administration for longer time periods (>2 hours), rough recoveries can occur. Preliminary results with S-ketamine CRIs showed better results in this respect, but further studies are warranted. Medetomidine CRI does decrease MAC about 30% at recommended dose rates. Cardiovascular function in comparison to lidocaine balance is moderately impaired, but horses show less intraoperative awakening following surgical stimulation. Recovery phase following medetomidine balance is clearly smoother than with any other regimen. In conclusion, lidocaine, ketamine, and medetomidine are mainly used for balanced anesthesia in horses. In cardiovascularly compromised patients, ketamine might be advantageous. If a smooth recovery phase is crucial, medetomidine should be the drug of choice.Clinical Techniques in Equine Practice 01/2007; 6(2):104-110.
- Asian Journal of Animal and Veterinary Advances - ASIAN J ANIM VET ADV. 01/2009; 4(4):191-199.