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: Effects of intermittent positive pressure ventilation (IPPV) on cardiopulmonary function were evaluated in horses anesthetized with total intravenous anesthesia using constant rate infusions of medetomidine (3.5 µg/kg/hr), lidocaine (3 mg/kg/hr), butorphanol (24 µg/kg/hr) and propofol (0.1 mg/kg/min) (MLBP-TIVA). Five horses were anesthetized twice using MLBP-TIVA with or without IPPV at 4-week interval (crossover study). In each occasion, the horses breathed 100% oxygen with spontaneous ventilation (SB-group, n=5) or with IPPV (CV-group, n=5), and changes in cardiopulmonary parameters were observed for 120 min. In the SB-group, cardiovascular parameters were maintained within acceptable ranges (heart rate: 33-35 beats/min, cardiac output: 27-30 l/min, mean arterial blood pressure [MABP]: 114-123 mmHg, mean pulmonary arterial pressure [MPAP]: 28-29 mmHg and mean right atrial pressure [MRAP]: 19-21 mmHg), but severe hypercapnea and insufficient oxygenation were observed (arterial CO2 pressure [PaCO2]: 84-103 mmHg and arterial O2 pressure [PaO2]: 155-172 mmHg). In the CV-group, normocapnea (PaCO2: 42-50 mmHg) and good oxygenation (PaO2: 395-419 mmHg) were achieved by the IPPV without apparent cardiovascular depression (heart rate: 29-31 beats/min, cardiac output: 17-21 l/min, MABP: 111-123 mmHg, MPAP: 27-30 mmHg and MRAP: 15-16 mmHg). MLBP-TIVA preserved cardiovascular function even in horses artificially ventilated.Journal of Veterinary Medical Science 09/2014; 76(12). DOI:10.1292/jvms.14-0077 · 0.88 Impact Factor
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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; 41(4). DOI:10.1111/vaa.12179 · 1.78 Impact Factor
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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. The Part 2 of this review will focus in the use of opioids and (2)-agonists. Databases usedPubmed and Web of Science. Search terms: horse, inhalant anaesthesia, balanced anaesthesia, partial intravenous anaesthesia, opioids, morphine, pethidine, butorphanol, methadone, fentanyl, alfentanil, remifentanil, sufentanil, xylazine, romifidine, detomidine, medetomidine and dexmedetomidine. Conclusions Different drugs and their combinations can be administered systemically in anaesthetized horses aiming to reduce the amount of the volatile agent while 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 07/2014; 42(1). DOI:10.1111/vaa.12196 · 1.78 Impact Factor