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1.
OBJECTIVE: To determine effects of low doses of medetomidine administered with and without butorphanol and glycopyrrolate to middle-aged and old dogs. DESIGN: Prospective randomized clinical trial. ANIMALS: 88 healthy dogs > or = 5 years old. PROCEDURE: Dogs were assigned randomly to receive medetomidine (2, 5, or 10 micrograms/kg [0.9, 2.3, or 4.6 micrograms/lb] of body weight, i.m.) alone or with glycopyrrolate (0.01 mg/kg [0.005 mg/lb], s.c.), medetomidine (10 micrograms/kg) and butorphanol (0.2 mg/kg [0.1 mg/lb], i.m.), or medetomidine (10 micrograms/kg), butorphanol (0.2 mg/kg), and glycopyrrolate (0.01 mg/kg). Anesthesia was induced with thiopental sodium and maintained with isoflurane. Degree of sedation and analgesia were determined before and after medetomidine administration. Respiratory rate, heart rate, and mean arterial blood pressure were determined 10 and 30 minutes after medetomidine administration. Adverse effects and amounts of thiopental and isoflurane used were recorded. RESULTS: Sedation increased after medetomidine administration in 79 of 88 dogs, but decreased in 7 dogs that received 2 or 5 micrograms of medetomidine/kg. Mean postsedation analgesia score and amounts of thiopental and isoflurane used were less in dogs that received medetomidine and butorphanol, compared with other groups. Respiratory rate, heart rate, and blood pressure were not different among groups. Significantly more adverse effects developed in dogs that did not receive glycopyrrolate. CONCLUSIONS AND CLINICAL RELEVANCE: Administration of medetomidine (10 micrograms/kg, i.m.) and butorphanol (0.2 mg/kg, i.m.) induced sedation and analgesia and reduced amounts of thiopental and isoflurane required for anesthesia in middle-aged and old dogs. Glycopyrrolate decreased frequency of medetomidine-associated adverse effects.  相似文献   

2.
The sedative and physiological effects of intramuscular medetomidine (20 and 40 μg/kg) in dogs were compared with those of xylazine (2 mg/kg). The efficacy of atipamezole (200 μg/kg), as an antagonist given 15 or 45 minutes after medetomidine (40 μg/kg) was studied. Following medetomidine, onset of sedation was rapid, and depth and duration of sedation were dose dependent. The higher dose produced jaw relaxation, depression of the pedal reflex, downward rotation of the eye and dogs could be positioned for radiography of the hips. Side effects were similar after either medetomidine or xylazine, and included bradycardia, a fall in respiratory rate and muscle tremor. Vomiting during induction was less frequent after medetomidine than after xylazine. Intramuscular administration of atipamezole rapidly reversed the sedative effects of medetomidine. Signs of arousal were seen within three minutes; all dogs could stand within 10 minutes and appeared clinically normal. Heart and respiratory rates rose, but did not return to presedation values. Relapse to sedation was not noted.  相似文献   

3.
Medetomidine at doses of 10, 20 or 30 microg/kg was administered along with 10 microg/kg buprenorphine intramuscularly to 48 dogs requiring sedation for various diagnostic or therapeutic procedures. The heart rate, respiratory rate and degree of sedation were recorded before and 30 minutes after administration of the drugs. Heart rate fell by a mean of 55 per cent and respiratory rate by a mean of 62 per cent. Mean sedation scores were increased in all groups. Administration of atipamezole at the end of the period of sedation produced rapid recoveries, with a mean time to standing of 12 minutes. Animals that were anaesthetised required much less thiopentone than the 10 mg/kg recommended after premedication with acepromazine maleate.  相似文献   

4.
OBJECTIVE: To determine sedative and cardiorespiratory effects of i.m. administration of medetomidine alone and in combination with butorphanol or ketamine in dogs. DESIGN: Randomized, crossover study. ANIMALS: 6 healthy adult dogs. PROCEDURES: Dogs were given medetomidine alone (30 micrograms/kg [13.6 micrograms/lb] of body weight, i.m.), a combination of medetomidine (30 micrograms/kg, i.m.) and butorphanol (0.2 mg/kg [0.09 mg/lb], i.m.), or a combination of medetomidine (30 micrograms/kg, i.m.) and ketamine (3 mg/kg [1.36 mg/lb], i.m.). Treatments were administered in random order with a minimum of 1 week between treatments. Glycopyrrolate was given at the same time. Atipamezole (150 micrograms/kg [68 micrograms/lb], i.m.) was given 40 minutes after administration of medetomidine. RESULTS: All but 1 dog (given medetomidine alone) assumed lateral recumbency within 6 minutes after drug administration. Endotracheal intubation was significantly more difficult when dogs were given medetomidine alone than when given medetomidine and butorphanol. At all evaluation times, percentages of dogs with positive responses to tail clamping or to needle pricks in the cervical region, shoulder region, abdominal region, or hindquarters were not significantly different among drug treatments. The Paco2 was significantly higher and the arterial pH and Pao2 were significantly lower when dogs were given medetomidine and butorphanol or medetomidine and ketamine than when they were given medetomidine alone. Recovery quality following atipamezole administration was unsatisfactory in 1 dog when given medetomidine and ketamine. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggested that a combination of medetomidine with butorphanol or ketamine resulted in more reliable and uniform sedation in dogs than did medetomidine alone.  相似文献   

5.
OBJECTIVE: To examine stress-related neurohormonal and metabolic effects of butorphanol, fentanyl, and ketamine administration alone and in combination with medetomidine in dogs. ANIMALS: 10 Beagles. PROCEDURE: 5 dogs received either butorphanol (0.1 mg/kg), fentanyl (0.01 mg/kg), or ketamine (10 mg/kg) IM in a crossover design. Another 5 dogs received either medetomidine (0.02 mg/kg) and butorphanol (0.1 mg/kg), medetomidine and fentanyl (0.01 mg/kg), medetomidine and ketamine (10 mg/kg), or medetomidine and saline (0.9% NaCI) solution (0.1 mL/kg) in a similar design. Blood samples were obtained for 6 hours following the treatments. Norepinephrine, epinephrine, cortisol, glucose, insulin, and nonesterified fatty acid concentrations were determined in plasma. RESULTS: Administration of butorphanol, fentanyl, and ketamine caused neurohormonal and metabolic changes similar to stress, including increased plasma epinephrine, cortisol, and glucose concentrations. The hyperglycemic effect of butorphanol was not significant. Ketamine caused increased norepinephrine concentration. Epinephrine concentration was correlated with glucose concentration in the butorphanol and fentanyl groups but not in the ketamine groups, suggesting an important difference between the mechanisms of the hyperglycemic effects of these drugs. Medetomidine prevented most of these effects except for hyperglycemia. Plasma glucose concentrations were lower in the combined sedation groups than in the medetomidine-saline solution group. CONCLUSIONS AND CLINICAL RELEVANCE: Opioids or ketamine used alone may cause changes in stress-related biochemical variables in plasma. Medetomidine prevented or blunted these changes. Combined sedation provided better hormonal and metabolic stability than either component alone. We recommend using medetomidine-butorphanol or medetomidine-ketamine combinations for sedation or anesthesia of systemically healthy dogs.  相似文献   

6.
OBJECTIVE: To determine the cardiorespiratory effects of preemptive atropine administration in dogs sedated with medetomidine. DESIGN: Randomized crossover trial. ANIMALS: 12 healthy adult dogs. PROCEDURES: Dogs underwent 6 treatments. Each treatment consisted of administration of atropine (0.04 mg/kg [0.018 mg/lb] of body weight, IM) or saline solution (0.9% NaCl, 1 ml, IM) and administration of medetomidine (10, 20, or 40 microg/kg [4.5, 9.1, or 18.2 microg/lb], IM) 10 minutes later. Treatments were administered in random order, with a minimum of 1 week between treatments. Cardiorespiratory effects before and after atropine and medetomidine administration were assessed. Duration of lateral recumbency and quality of sedation and recovery were assessed. RESULTS: Bradycardia (heart rate < 60 beats/min) was seen in all dogs when saline solution was administered followed by medetomidine, and the dose of medetomidine was not associated with severity or frequency of bradycardia or second-degree heart block. However, a medetomidine dose-dependent increase in mean and diastolic blood pressures was observed, regardless of whether dogs received saline solution or atropine. Preemptive atropine administration effectively prevented bradycardia and second-degree heart block but induced pulsus alternans and hypertension. The protective effects of atropine against bradycardia lasted 50 minutes. Blood gas values were within reference limits during all treatments and were not significantly different from baseline values. Higher doses of medetomidine resulted in a longer duration of lateral recumbency. CONCLUSIONS AND CLINICAL RELEVANCE: Preemptive administration of atropine in dogs sedated with medetomidine effectively prevents bradycardia for 50 minutes but induces hypertension and pulsus alternans.  相似文献   

7.
Sedative effects of medetomidine, a potent selective and specific alpha 2-adrenoceptor agonist, were evaluated in pigs using 5 different doses (30, 50, 80, 100 and 150 micrograms/kg of body weight) and compared with those of xylazine (2 mg/kg). Atropine (25 micrograms/kg) was mixed with both drugs to prevent severe bradycardia. All drugs were administered intramuscularly. Medetomidine at a dosage of 30 micrograms/kg produced more potent sedation than xylazine. The depth of sedation induced by medetomidine was dose dependent within the range from 30 to 80 micrograms/kg. At 100 or 150 micrograms/kg, the depth of sedation was mostly the similar level to that at 80 micrograms/kg but the duration was prolonged. The degree of muscle relaxation produced by medetomidine also seemed to be dose dependent from 30 to 80 micrograms/kg and was stronger than that produced by xylazine. An increase in the duration of muscle relaxation was dose dependent up to 150 micrograms/kg. No analgesic effect was produced by xylazine, however moderate analgesia was obtained by medetomidine. There were no marked changes in heart rate and respiratory rate during the observation period in pigs of any groups, however mild hypothermia after the administration of both drugs was observed. From these results, medetomidine has a significant and dose-dependent sedative effects which are much more potent than that of xylazine, and a combination of 80 micrograms/kg of medetomidine and 25 micrograms/kg of atropine is suitable for sedation with lateral recumbency and moderate muscle relaxation without notable side effects in pigs.  相似文献   

8.
ABSTRACT

Aim: To evaluate the sedative and clinical effects of I/V xylazine, detomidine, medetomidine and dexmedetomidine in miniature donkeys.

Methods: Seven clinically healthy, male adult miniature donkeys with a mean age of 6 years and weight of 105?kg, were assigned to five I/V treatments in a randomised, cross-over design. They received either 1.1?mg/kg xylazine, 20?μg/kg detomidine, 10?μg/kg medetomidine, 5?μg/kg dexmedetomidine or saline, with a washout period of ≥7 days. The degree of sedation was scored using a 4-point scale by three observers, and heart rate (HR), respiration rate (RR), rectal temperature and capillary refill time (CRT) were recorded immediately before and 5, 10, 15, 30, 60, 90 and 120 minutes after drug administration.

Results: All saline-treated donkeys showed no sedation at any time, whereas the donkeys treated with xylazine, detomidine, medetomidine and dexmedetomidine had mild or moderate sedation between 5 and 60 minutes after treatment, and no sedation after 90 minutes. All animals recovered from sedation without complication within 2 hours. The mean HR and RR of saline-treated donkeys did not change between 0 and 120 minutes after administration, but the mean HR and RR of donkeys treated with xylazine, detomidine, medetomidine and dexmedetomidine declined between 5 and 60 minutes after drug administration. The mean rectal temperature of all treated donkeys did not change between 0 and 120 minutes after administration. The CRT for all donkeys was ≤2 seconds at all times following each treatment.

Conclusions and clinical relevance: Administration of xylazine at 1.1?mg/kg, detomidine at 20?μg/kg, medetomidine at 10?μg/kg and dexmedetomidine at 5?μg/kg resulted in similar sedation in miniature donkeys. Therefore any of the studied drugs could be used for sedation in healthy miniature donkeys.  相似文献   

9.
O bjectives : To compare reaction to injection, sedation and propofol induction dose in dogs receiving acepromazine–buprenorphine pre-anaesthetic medication by the intramuscular or subcutaneous routes.
M ethods : Fifty-two client owned dogs of American Society of Anesthesiologists grade I or II anaesthetised for diagnostic imaging. Dogs were randomly assigned to receive acepromazine 0·03 mg/kg and buprenorphine 0·02 mg/kg either intramuscular or subcutaneous. Reaction to injection was scored. Sedation was compared before and one hour after pre-anaesthetic medication. Propofol was administered in 1 mg/kg incremental injections until tracheal intubation was achieved. Total propofol dose was recorded.
R esults : Reaction to injection was significantly greater (P=0·009) in the intramuscular group compared to the subcutaneous group. Sedation scores were not significantly different (P=0·523) between the intramuscular and the subcutaneous group. There was no statistically significant difference in propofol dose for induction (P=0·7).
Clinical Significance: Acepromazine–buprenorphine pre-anaesthetic medication provides a similar degree of sedation whether administered by the intramuscular or subcutaneous route. The intramuscular route is more painful compared to the subcutaneous route.  相似文献   

10.
Hemodynamic Effects of Medetomidine in the Dog: A Dose Titration Study   总被引：4，自引：0，他引：4  
Objective —To characterize the hemodynamic effects of medetomidine administered intravenously at doses ranging from 1 to 20 μg/kg, and to determine whether these effects are dose dependent. Study Design —Prospective randomized multidose trial. Animals —Twenty-five clinically normal male beagles (5 groups of 5), aged 1 to 4 years and weighing 13.5 ±1.7 kg. Methods —Medetomidine, at a dose of 1, 2, 5, 10, or 20 μg/kg, was administered intravenously at time 0. Heart rate, arterial pressure, central venous pressure, mean pulmonary arterial pressure, pulmonary capillary wedge pressure, body temperature, cardiac output, and packed cell volume were measured immediately before and at selected times after medetomidine administration (3, 7, 10, 20, 30, 40, 50, and 60 minutes in all groups, at 90 minutes for the 10 and 20 μg/kg groups, and at 120 minutes for the highest dose). Cardiac index, stroke index, rate-pressure product, systemic vascular resistance index, pulmonary vascular resistance index, and left and right ventricular stroke work indices were calculated. The degree of sedation was subjectively scored by an observer who was blinded to the treatment used. Results —Heart rate, rate-pressure product, cardiac index, and left and right ventricular stroke work indices decreased below baseline values. Central venous pressure and systemic vascular resistance index increased above baseline measurements. Except in the 2 μg/kg group, after an initial and short lasting increase, a prolonged decrease in arterial pressure was observed. Conclusions —Hemodynamic changes were observed with the intravenous (IV) administration of medetomidine, at any dose. However, the two lowest doses (1 and 2 μg/kg) produced less cardiovascular depression. Clinical Relevance —Medetomidine is an alpha-2 adrenoceptor agonist widely used in dogs, producing sedation, analgesia and cardiovascular depression. When using IV medetomidine, a reduction of the recommended dosage (ie, ±30 to 40 μg/kg) by up to 6 times did not significantly influence the cardiovascular effects.  相似文献   

11.
Sedative effects of romifidine in the dog   总被引：5，自引：0，他引：5  
The sedative and physiological effects of intravenous romifidine at 0, 20, 40, 80 and 120 μg/kg were investigated in five clinically normal adult male beagle dogs in a blind study using a Latin square design. Following the injection of romifidine, the dogs became ataxic and stood with a wide-based stance, they exhibited signs of skeletal muscle relaxation and their heads were lowered. All the dogs became recumbent and there was a reduction in the heart and respiratory rates. Increasing the dose from 20 to 40 μg/kg, or higher, produced a significant reduction in heart rate. There was an increase in the sedation score following even low doses of romifidine, and although measures of sedation showed no differences among romifidine doses, subjectively, the higher doses produced a more consistent effect. Dogs given lower doses of romifidine regained a standing position more rapidly than following the higher doses, although this effect was not significantly different. A second blind study compared the sedative effects of intravenous romifidine, at 40 and 80 μg/kg, with mede-tomidine at 10 μg/kg in six adult beagles. The cardiopulmonary and sedative effects were not significantly different between all regimens, although medetomidine at 10 μg/kg appeared to be intermediate in effect between romifidine at 40 and 80 μ/kg. The sedative and physiological effects of romifidine in dogs appear to be similar to other α2-adrenoceptor agonists. Intravenous administration provided sedation which might be clinically useful.  相似文献   

12.
The efficacies and ease of administration of four oral preanesthetic sedation protocols were compared in 18 adult, male rhesus macaques (Macaca mulatta) to achieve heavy sedation and alleviate anxiety, agitation, and potential trauma associated with remote anesthesia induction. The macaques, with average age and weight of 10 yr and 12.5 kg, respectively, were randomly assigned to one of four groups. Group 1 was given 10 mg/kg tiletaminezolazepam and 0.05 mg/kg medetomidine p.o., group 2 was given 1 mg/kg midazolam and 20 mg/kg ketamine p.o., group 3 was given 20 mg/kg ketamine and 0.05 mg/kg medetomidine p.o., and group 4 was given 3 mg/kg midazolam p.o. All protocols produced effects ranging from mild sedation to no response to noxious stimuli, depending on the success of administration. The mean interval to peak effect was 27-43 min in all groups. Ketamine and medetomidine provided significantly better sedation than midazolam alone; there were no other statistically significant differences among the four protocols. Oral tiletamine-zolazepam and medetomidine provided smooth, mild to moderate sedation with few side effects. The midazolam and ketamine combination resulted in severe ataxia. Orally administered ketamine and medetomidine provided smooth, easily reversible, heavy sedation leading to no response to noxious stimuli. Midazolam alone provided only mild sedation. No statistically significant differences in palatability of the four protocols were identified. Orally administered ketamine and medetomidine (group 3) provided the most consistently heavy sedation. A compounding pharmacy may be able to increase the palatability and level of acceptance of these combinations. Alternatively, oral midazolam syrup is well accepted by some animals and provides a mild sedative and calming effect, which may decrease stress associated with the induction of anesthesia via darting, pole syringes, etc.  相似文献   

13.
OBJECTIVE: To assess the sedative and cardiopulmonary effects of medetomidine and xylazine and their reversal with atipamezole in calves. ANIMALS: 25 calves. PROCEDURES: A 2-phase (7-day interval) study was performed. Sedative characteristics (phase I) and cardiopulmonary effects (phase II) of medetomidine hydrochloride and xylazine hydrochloride administration followed by atipamezole hydrochloride administration were evaluated. In both phases, calves were randomly allocated to receive 1 of 4 treatments IV: medetomidine (0.03 mg/kg) followed by atipamezole (0.1 mg/kg; n = 6), xylazine (0.3 mg/kg) followed by atipamezole (0.04 mg/kg; 7), medetomidine (0.03 mg/kg) followed by saline (0.9% NaCl; 6) solution (10 mL), and xylazine (0.3 mg/kg) followed by saline solution (10 mL; 6). Atipamezole or saline solution was administered 20 minutes after the first injection. Cardiopulmonary variables were recorded at intervals for 35 minutes after medetomidine or xylazine administration. RESULTS: At the doses evaluated, xylazine and medetomidine induced a similar degree of sedation in calves; however, the duration of medetomidine-associated sedation was longer. Compared with pretreatment values, heart rate, cardiac index, and PaO(2) decreased, whereas central venous pressure, PaCO(2), and pulmonary artery pressures increased with medetomidine or xylazine. Systemic arterial blood pressures and vascular resistance increased with medetomidine and decreased with xylazine. Atipamezole reversed the sedative and most of the cardiopulmonary effects of both drugs. CONCLUSIONS AND CLINICAL RELEVANCE: At these doses, xylazine and medetomidine induced similar degrees of sedation and cardiopulmonary depression in calves, although medetomidine administration resulted in increases in systemic arterial blood pressures. Atipamezole effectively reversed medetomidine- and xylazine-associated sedative and cardiopulmonary effects in calves.  相似文献   

14.
Medetomidine 10 μg/kg, was combined with butorphanol 0.1 mg/kg and administered intramuscularly to 27 dogs requiring sedation for various diagnostic or therapeutic procedures. All the dogs became deeply sedated. Heart rate fell by a mean of 55 per cent. Eighteen dogs showed signs of pain as the combination was injected. Sedation was sufficient for the intended procedure to be carried out in 25 of the dogs. General anaesthesia was induced in four dogs — the mean dose of thiopentone required for induction of anaesthesia was 2 mg/kg. Administration of atipamezole at the end of the procedure produced rapid and sudden recoveries in all the dogs, with a mean time to standing of nine minutes.  相似文献   

15.
Medetomidine as a premedicant in dogs and its reversal by atipamezole   总被引：2，自引：0，他引：2  
Medetomidine (10, 20, 40 μg/kg) was used as a premedicant before thiopentone, halothane and nitrous oxide anaesthesia in 60 dogs undergoing a variety of elective surgical and diagnostic procedures at the University of Liverpool Small Animal Hospital. The efficacy of the sedation produced by the three dose groups was evaluated using a sedation scoring system which is presented. Induction of anaesthesia was accomplished using 1–25 per cent thiopentone sodium administered slowly to effect. The mean dose of thiopentone required for intubation following 10 μ-g/kg medetomidine (group 1) was 6–9 mg/kg (SD ± 2–3 mg/kg), following 20 μ-g/kg medetomidine (group 2) was 4–5 mg/kg (SD ± 1–6 mg/kg) and following 40 μg/kg (group 3) was 2–4 mg/kg (SD ± 2–5 mg/kg). Induction of anaesthesia was generally smooth and significant apnoea (greater than 45 seconds) was not noted. Anaesthesia was maintained in all cases using halothane vapourised in a one part oxygen to two parts nitrous oxide mixture, delivered to the patient via a suitable non-breathing circuit (Magill, Bain or T Piece). At the conclusion of the procedure, atipamezole (50, 100, 200 μg/kg) was administered intramuscularly to half of the dogs in each group (10 dogs). Dogs receiving atipamezole recovered rapidly and smoothly to sternal recumbency, group 1 taking 8-5 minutes (SD ± 2–7 minutes), group 2 taking 11-8 minutes (SD ± 3–6 minutes), and group 3 taking 12-6 minutes (sd ± 4–5 minutes). When atipamezole was not administered a dose dependent increase in recumbency time occurred.  相似文献   

16.
Twenty-eight dogs were randomly allocated into two groups. They were premedicated with either 10 or 20 microg/kg buprenorphine and 0.05 mg/kg acepromazine administered intramuscularly, and then anaesthetised with intravenous thiopentone to effect and maintained with isoflurane in 100 per cent oxygen. The dogs underwent routine castration, and a second dose of 10 microg/kg buprenorphine was administered four hours after the first or 20 microg/kg six hours after the first dose. Levels of pain and sedation were scored on a visual analogue scale and in terms of the dogs' requirement for rescue analgesia, and mechanical nociceptive thresholds were measured at the hock and wound at premedication and one, two, three, four, five, six, seven, 10 and 21 to 22 hours later. Pain scores were low in both groups, with a trend for lower scores in the high dose group; administration of the second dose of buprenorphine further decreased the pain scores. Buprenorphine produced good preoperative sedation and the level of sedation decreased over time after surgery. Administration of the second high dose of buprenorphine did not increase the level of sedation. Both doses of buprenorphine prevented hyperalgesia at the wound and hock postoperatively. Three dogs given the low dose and one dog given the high dose required rescue analgesia with carprofen.  相似文献   

17.
Sedative and analgesic effects of medetomidine in dogs   总被引：3，自引：0，他引：3  
The sedative and analgesic effects of medetomidine were studied in 18 laboratory beagles in a randomized cross-over study which was carried out in a double-blind fashion. Xylazine was included as a positive control and placebo as a negative control. Medetomidine was used at doses of 10, 30, 90 and 180 micrograms/kg i.m. compared to a dose of 2.2 mg/kg xylazine i.m. Parameters closely related to sedation were used to measure the degree of sedation. These were a posture variable (including evaluation of the dog's posture without external disturbance and resistance when laid recumbent) and a relaxation variable (including relaxation of the jaws, upper eyelids and anal sphincter). The first signs of sedation were recorded 1.5-3.5 min after administration of both drugs. The dogs sat down at 0.6-2.6 min post-injection and became prone at 1.9-5.9 min. Medetomidine dose-dependently affected the posture of the dogs and the relaxation variable--the higher the dose, the stronger and longer lasting the effect recorded. The sedative effect of xylazine was comparable to a medetomidine dose of 30 micrograms/kg. The analgesic effect was assessed as changes in the response to superficial pain induced by electrical stimuli. The response threshold increased significantly with both drugs and the effect of medetomidine was dose-dependent. The effects of the doses of 30 micrograms/kg medetomidine and 2.2 mg/kg xylazine did not differ significantly. In summary, medetomidine possessed an excellent sedative effect associated with analgesia in dogs.  相似文献   

18.
OBJECTIVE: To evaluate the effect of medetomidine on minimum alveolar concentration (MAC), respiratory rate, tidal volume, minute volume (V(M)), and maximum inspiratory occlusion pressure (IOCP(max)) in halothane- and isoflurane-anesthetized dogs. ANIMALS: 6 healthy adult dogs (3 males and 3 females). PROCEDURE: The MAC of both inhalants was determined before and 5, 30, and 60 minutes after administration of medetomidine (5 microg/kg, IV). Dogs were subsequently anesthetized by administration of halothane or isoflurane and administered saline (0.9% NaCl) solution IV or medetomidine (5 microg/kg, IV). Respiratory variables and IOCP(max) were measured at specific MAC values 15 minutes before and 5, 30, and 60 minutes after IV administration of medetomidine while dogs breathed 0% and 10% fractional inspired carbon dioxide (FICO2). Slopes of the lines for VM/FICO2 and IOCP(max)/FICO2 were then calculated. RESULTS: Administration of medetomidine decreased MAC of both inhalants. Slope of V(M)/FICO2 increased in dogs anesthetized with halothane after administration of medetomidine, compared with corresponding values in dogs anesthetized with isoflurane. Administration of medetomidine with a simultaneous decrease in inhalant concentration significantly increased the slope for V(M)/FICO2, compared with values after administration of saline solution in dogs anesthetized with halothane but not isoflurane. Values for IOCP(max) did not differ significantly between groups. CONCLUSIONS AND CLINICAL RELEVANCE: Equipotent doses of halothane and isoflurane have differing effects on respiration that are most likely attributable to differences in drug effects on central respiratory centers. Relatively low doses of medetomidine decrease the MAC of halothane and isoflurane in dogs.  相似文献   

19.
OBJECTIVE: To assess duration of actions of butorphanol, medetomidine, and a butorphanol-medetomidine combination in dogs given subanesthetic doses of isoflurane (ISO). ANIMALS: 6 healthy dogs. PROCEDURE: Minimum alveolar concentration (MAC) values for ISO were determined. for each dog. Subsequently, 4 treatments were administered to each dog (saline [0.9% NaCl] solution, butorphanol [0.2 mg/kg of body weight], medetomidine [5.0 microg/kg], and a combination of butorphanol [0.2 mg/kg] and medetomidine [5.0 microg/kg]). All treatments were administered IM to dogs concurrent with isoflurane; treatment order was determined, using a randomized crossover design. Treatments were given at 7-day intervals. After mask induction with ISO and instrumentation with a rectal temperature probe, end-tidal CO2 and anesthetic gas concentrations were analyzed. End-tidal ISO concentration was reduced to 90% MAC for each dog. A tail clamp was applied 15 minutes later. After a positive response, 1 of the treatments was administered. Response to application of the tail clamp was assessed at 15-minute intervals until a positive response again was detected. RESULTS: Duration of nonresponse after administration of saline solution, butorphanol, medetomidine, and butorphanol-medetomidine (mean +/- SD) was 0.0+/-0.0, 1.5+/-1.5, 2.63+/-0.49, and 5.58+/-2.28 hours, respectively. Medetomidine effects were evident significantly longer than those for saline solution, whereas effects for butorphanol-medetomidine were evident significantly longer than for each agent administered alone. CONCLUSION AND CLINICAL RELEVANCE: During ISO-induced anesthesia, administration of medetomidine, but not butorphanol, provides longer and more consistent analgesia than does saline solution, and the combination of butorphanol-medetomidine appears superior to the use of medetomidine or butorphanol alone.  相似文献   

20.
OBJECTIVE: To compare sedative, analgesic, and cardiopulmonary effects after IV administration of medetomidine (20 microg/kg), medetomidine-hydromorphone (20 microg of medetomidine/kg and 0.1 mg of hydromorphone/kg), and medetomidine-butorphanol (20 microg of medetomidine/kg and 0.2 mg of butorphanol tartrate/kg) in dogs. ANIMALS: 6 dogs healthy mixed-breed dogs. PROCEDURE: Instruments were surgically inserted, and heart rate (HR), respiratory rate (RR), systolic arterial pressure (SAP), mean arterial pressure (MAP), diastolic arterial pressure (DAP), mean pulmonary arterial pressure (MPAP), pulmonary capillary wedge pressure (PCWP), central venous pressure (CVP), core body temperature, and cardiac output (CO) were measured 0, 5, 10, 15, 30, 45, and 60 minutes after injection. Cardiac index (CI), stroke volume (SV), stroke index (SI), systemic vascular resistance (SVR), and pulmonary vascular resistance (PVR) were calculated. Arterial samples for blood gas analysis were collected 0, 15, and 45 minutes after injection. Intensity of analgesia, degree of sedation, and degree of muscle relaxation were evaluated at aforementioned time points and 75, 90, 120, 150, 180, and 210 minutes after injection. RESULTS: Administration of medetomidine, medetomidine-hydromorphone, and medetomidine-butorphanol was associated with increases in SAP, MAP, DAP, MPAP, PCWP, CVP, SVR, PVR, core body temperature, and PaCO2 and decreases in HR, CO, CI, SV, SI, RR, pH, and PaO2. Clinically important differences were not detected among treatments. Medetomidine-hydromorphone and medetomidine-butorphanol provided a longer duration of sedation and better quality of analgesia, compared with medetomidine alone. CONCLUSIONS AND CLINICAL RELEVANCE: Medetomidine-hydromorphone or medetomidine-butorphanol is associated with improved analgesia and sedation but has cardiopulmonary effects comparable to those for medetomidine alone.  相似文献   

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