Determination of the Minimum Alveolar Concentration (MAC) and Physical Response to Sevoflurane Inhalation in Horses.

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ABSTRACT. To investigate an adequate infusion rate of propofol for total intravenous anesthesia (TIVA) in horses, the minimum infusion rate (MIR) comparable to the minimum alveolar anesthetic concentration (MAC) of inhalation anesthetic was determined under constant ventilation condition by intermittent positive pressure ventilation (IPPV). In addition, arterial propofol concentration was measured to determine the concentration corresponding to the MIR (concentration preventing reaction to stimulus in 50% of population, Cp 50 ). Further, 95% effective dose (ED 95 ) was estimated as infusion rate for acquiring adequate anesthetic depth. Anesthetic depth was judged by the gross purposeful movement response to painful stimulus. MIR and Cp 50 were 0.10 ± 0.02 mg/kg/min and 5.3 ± 1.4 µg/ml, respectively. ED 95 was estimated as 0.14 mg/kg/min (1.4MIR).

Section: Measurement Of Mirmentioning

confidence: 99%

The Minimum Infusion Rate (MIR) of Propofol for Total Intravenous Anesthesia after Premedication with Xylazine in Horses

Oku

Ohta

Yamanaka

et al. 2005

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“…No horse needed any additional injectable anesthetics during transition and maintenance phases. All horses were ventilated by IPPV with 14-25 cmH 2 …”

Section: Mkm-os Anesthesia and Surgerymentioning

confidence: 99%

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

Kushiro

Yamashita

Umar

et al. 2005

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.

“…63 (5): [527][528][529][530][531][532] 2001 Sevoflurane (Sev) is an excellent anesthetic with a very low blood/gas partition coefficient of 0.6, which realizes rapid induction and waking [20], and it is widely used in humane medicine [9]. The drug is being used in equine medicine and its minimum alveolar concentration (MAC) is known to be 2.31% [1]. Sev-anesthesia is considered to be more useful especially for orthopedic surgery than halothane or isoflurane (Iso)-anesthesia because it provides excellent recoveries in horses [5].…”

mentioning

confidence: 99%

“…The drug is being used in equine medicine and its minimum alveolar concentration (MAC) is known to be 2.31% [1]. Sev-anesthesia is considered to be more useful especially for orthopedic surgery than halothane or isoflurane (Iso)-anesthesia because it provides excellent recoveries in horses [5].…”

mentioning

confidence: 99%

Time-Related Changes of the Cardiovascular System during Maintenance Anesthesia with Sevoflurane and Isoflurane in Horses.

Yamanaka

Oku

Koyama

et al. 2001

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ABSTRACT. To clarify time-related changes in equine cardiovascular system during maintenance anesthesia (180 min, 1.2 minimum alveolar concentration) with sevoflurane (Sev-group) compared to isoflurane (Iso-group) as the basis for clinical use of Sev, horses were examined for the heart rate (HR), mean arterial pressure (MAP), cardiac index (CI), systemic vascular resistance( SVR) and pre-ejection period (PEP)/ejection time (ET) that is an index of the cardiac contractility. The HR was almost 30 beats/min in both groups without significant temporal change. MAP was significantly elevated with time but there was no significant difference between the groups. In the Sev-group, CI remained unchanged but the significant increase of CI with time was observed in the Iso-group. In the Sev-group SVR was significantly higher than that of the Iso-group and increased with time. No significant difference of PEP/ET was seen between the groups, but PEP/ET lowered with time in the Iso-group in association with prolonged ET. The results indicated that the time-dependent elevation of MAP in the Sev-group reflected increased SVR without increase of CI and that it reflected increased CI resulting from increased stroke volume in the Iso-group in association with lowered PEP/ET, that is, increased cardiac contractility. KEY WORDS: cardiovascular system, equine, pulsed doppler echocardiography, sevoflurane.J. Vet. Med. Sci. 63 (5): [527][528][529][530][531][532] 2001 Sevoflurane (Sev) is an excellent anesthetic with a very low blood/gas partition coefficient of 0.6, which realizes rapid induction and waking [20], and it is widely used in humane medicine [9]. The drug is being used in equine medicine and its minimum alveolar concentration (MAC) is known to be 2.31% [1]. Sev-anesthesia is considered to be more useful especially for orthopedic surgery than halothane or isoflurane (Iso)-anesthesia because it provides excellent recoveries in horses [5]. Halothane and Iso have been well examined for effects on the time-related changes of cardiovascular system in horses [6,17]. If the surgeries are prolonged, it should be necessary for the anesthetists to know the time-related effects of cardiovascular system with anesthetics. But there are no data for the time-related changes during Sev-anesthesia in the equine cardiovascular system, except for dose-dependent decrease in the arterial pressure and cardiac index (CI) [2].For non-invasive measuring of CI, the Pulsed Doppler echocardiography was reported to be useful to give data closely correlated with those of the dye dilution or thermodilution methods [12]. In humane medicine, pre-ejection period (PEP)/ejection time (ET), an index of the cardiac contractility, is known to be calculated from the wave shape of the aortic flow velocity and electrocardiogram (ECG) using the pulsed doppler echocardiography [3,18,19].To search for time-related alterations in equine cardiovascular system during maintenance anesthesia with Sev, in the present study, indices of the cardiovascular system such as hear...