• Journal of Veterinary Clinics
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• v.16 no.2
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• pp.352-362
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• 1999

Thiopental sodium is known as ultrashort-acting barbiturates and can be employed advantageously for numerous conditions. But thiopental has the side effects of cardiovascular and respiratory systems which has barbiturates and are depend on the dose of thiopental. The side effects are reduced when the thiopental is preceded by a tranquilizer and sedative. In these drugs, benzodiazepines have the minimal effects of cardiovascular and respiratory systems. In this study, the effects of midazolam preanesthetic administration, followed by thiopental anesthetic induction, on cardiovascular system and thiopental induction requirement were studied in 14 mixed breed dogs. Cardiovascular data were recorded baseline, after premedication of saline 0.45 ml/kg or midazolam 0.1, 0.2, 0.4, 0.8 mg/kg, intubation, and 5, 10, 15, 20, 30 minutes after intubation. Extubation, head-up, sternal recombency, standing, and walking recovery times were recorded. The results were summarized as follows; (1) The 0.1, 0.2, 0.4, and 0.8 mg/kg dosages of midazolam insignificantly decreased thiopental dose requirement necessary to accomplish intubation by 6, 20, 21 and 28%. (2) The 0.1, 0.2, 0.4, and 0.8 mg/kg dosages of midazolam insignificantly reduced the times of extubation, head-up, sternal recumbency, standing, and walking recovery. (3) Midazolam was effective in reducing the frequency and duration of arrhythmia after intubation. (4) Heart rates of preanestheic midazolam administraion groups increased after thiopental injection which insignificantly changed smaller than those of control group. (5) Arterial blood pressures did not vary significantly among groups.

• The Korean Journal of Pain
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• v.6 no.2
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• pp.231-236
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• 1993

Clonidine, a centrally-acting antihypertensive agent known to reduce central sympathetic outflow and modulate presynaptic transmitter's release, has shown to suppress central noradrenergic hyperactivity induced by immobilization stress in animals, by decreasing the MAC of halothane and the dose of narcotics required to prevent reflex cardiovascular response to noxious stimuli, and to have potent analgesic properties in humans. These characteristics suggest that clonidine might be a useful adjunct to the anesthetic management of patients with preexisting hypertension. Accordingly, we determined the clinical efficacy and safety on analgesia, sedation and hemodynamic stability in the perioperative period. Thirty patients(ASA physical status II-III) with a history of arterial hypertension, scheduled for elective orthopedic surgery were randomly assigned to two groups. We applied CPA-clonidine patch($6.9\;mg/cm^2$, 0.2 mg delivered daily) or placebo patch to each groups, 48 hours prior to induction of anesthesia. Antihypertensive medication was continued until the morning of the scheduled surgery. All patients received premedication of atropine and lorazepam, and induced anesthesia with thiopental and succinylcholine, and maintained with enflurane and 50% nitrous oxide, while sustaining the BP and pulse rate at acceptable range. For the relief of pain postoperatively, diclofenac and fentanyl were administered intramuscularly on demand. The results were as follows: 1) The change of hemodynamic responses in clonidine group was less compared to the placebo group. 2) Intraoperative anesthetic requirement for enflurane in clonidine group were significantly lower than placebo group. 3) Postoperative analgetic requirement in clonidine group were significantly lower than placebo group. In clonidine group, 5 cases out of 15 cases were required no analgetics, and the incidence of administration of additional fentanyl was decreased to 5 cases, comparing with 10 cases in placebo group.

• Korean Journal of Veterinary Research
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• v.39 no.3
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• pp.616-627
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• 1999

This study was performed to evaluate anesthetic and cardiovascular effects of xylazine/fentanyl/azaperone and medetomidine/midazolam as preanesthetics and their combinations with antagonists in halothane-anesthetized dogs. Eight clinically healthy dogs($4.54{\pm}2.16kg$) were used at the interval of more than 14 days between experiments in turn for propionyl promazine(PP 0.3mg/kg, IM), xylazine/fentanyl/azaperone(XFA 2mg/kg, 0.0137mg/kg, 0.11mg/kg, IM), medetomidine/midazolam(MM 0.02mg/kg, 0.3mg/kg, IM), combination of XFA and their antagonists (yohimbine 0.05mg/kg, naloxon 0.0005mg/kg, IV) and combination of MM and their antagonist(atipamezole 0.08mg/kg IM). The sedation induction times in XFA($2.56{\pm}1.01min$) and MM($5.44{\pm}2.07min$) groups were significantly better than that of PP group($10.75{\pm}2.38min$)(p < 0.05). The thiopental sodium dose required for tracheal intubation in XFA($2.38{\pm}3.38mg/kg$) and MM($3.91{\pm}3.47mg/kg$) groups were significantly less than that of PP group($12.57{\pm}2.13mg/kg$)(p < 0.05). All time indices expressing the recovery(pedal reflex recurrence time, extubation time, arousal time, standing time and walking time) were significantly shorter in the combination groups of XFA or MM with their antagonists than in PP, XFA and MM groups(p < 0.05). The suppressions of cardiovascular function of XFA and MM were more than that of PP. Heart rate and cardiac output were recovered by the antagonists of XFA and MM, but mean arterial pressure were not recovered by the antagonists. PP induced apnea in 4 out of 8 dogs, but XFA in none and MM in one. The present study suggested that for rapid sedation, prevention of apnea after intubation and rapid recovery after halothane cessation, combinations of xylazine/fentanyl/azaperone or medetomidine/midazolam with their antagonists are recommendable as preanesthetic method in gas anesthetised dogs with normal cardiovascular function.