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Query: UMLS:C0011570 (depression)
 172,036 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The sedative action of medetomidine (-ketamine) was studied in 12 captive Norwegian semidomesticated reindeer (NR), including 4 newborn calves, and in 7 free-living Svalbard reindeer (SR). Medetomidine, with or without ketamine, caused effective, reliable immobilization in NR. Doses of 50-200 micrograms/kg medetomidine alone or 30-125 micrograms/kg medetomidine combined with greater than or equal to 300 micrograms/kg ketamine induced complete immobilization, good muscle relaxation and persistent, deep sedation with little respiratory depression in NR; SR required higher doses. Atipamezole successfully antagonized medetomidine (-ketamine) resulting in rapid and persistent reversal of immobilization in all cases (NR and SR). Both medetomidine and atipamezole had wide safety margins and no conspicuous lasting side effects after reversal.
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PMID:Immobilization of Norwegian reindeer (Rangifer tarandus tarandus) and Svalbard Reindeer (R. t. platyrhynchus) with medetomidine and medetomidine-ketamine and reversal of immobilization with atipamezole. 198 84

The sedative effects of medetomidine at doses of 20 and 40 micrograms/kg im given alone or followed 16-18 min later by fentanyl (2 micrograms/kg iv) was investigated in 6 bitches of mixed breeds. The higher dose of medetomidine alone caused the greater degree of sedation, but two bitches were only lightly sedated with either dose. Side effects noted in some cases included apparent pain on injection, vomiting on induction of sedation, bradycardia, slowing of respiratory rate, cyanosis and muscular twitching. The intravenous injection of fentanyl caused a marked increase in depth of sedation in all animals, inducing a condition similar to neuroleptanaesthesia in which the eyes were rotated downward and the pedal reflex abolished. Slight twitching and sensitivity to sound occurred immediately after fentanyl injection, but this was transient. The cardiopulmonary effects of medetomidine (40 micrograms/kg im) followed 20 min later by either fentanyl (2 micrograms/kg iv) or a saline placebo were investigated in 4 beagle dogs. Medetomidine caused bradycardia, hypotension and reduced respiratory rate, inducing an intermittent respiratory pattern. The iv injection of fentanyl did not further alter the heart or respiratory rate or blood pressure. However there was a small but significant decrease in arterial oxygen tension and rise in arterial carbon dioxide tension. indicating some respiratory depression. We conclude that the use of intravenous fentanyl to dogs already sedated with medetomidine could prove useful in clinical cases where the initial sedation with medetomidine has proved inadequate.
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PMID:The use of medetomidine/fentanyl combinations in dogs. 257 Dec 71

We compared the ability of 2 alpha 2-adrenergic receptor antagonists, atipamezole and yohimbine, to reverse medetomidine-induced CNS depression and cardiorespiratory changes in lambs. Twenty lambs (7.8 +/- 2.6 kg) were randomly allotted to 4 treatment groups (n = 5). Each lamb was given medetomidine (30 micrograms/kg of body weight, i.v.), followed in 15 minutes by i.v. administration of atipamezole (30 or 60 micrograms/kg), yohimbine (1 mg/kg), or 0.9% NaCl (saline) solution. Medetomidine caused lateral recumbency in 1 to 2 minutes in all treated lambs. Medetomidine significantly (P < 0.05) decreased heart rate at 5 and 10 minutes after its administration. Heart rate remained above 120 beats/min, and severe bradycardia (< or = 70 beats/min) and other arrhythmias did not occur throughout the study. Medetomidine also induced tachypnea in all treated lambs. The tachypnea was abolished by atipamezole and yohimbine, but not by saline solution administration. The medetomidine-induced tachypnea did not significantly affect arterial pH and PaCO2. Arterial oxygen tension was within acceptable range (PaO2 = 71 to 62 mm of Hg), but was lower than expected. Administration of atipamezole, yohimbine, or saline solution did not change PaO2 significantly. Lambs treated with 30 or 60 micrograms of atipamezole/kg were able to walk unassisted in 2.4 +/- 0.4 and 2.3 +/- 0.7 minutes, respectively, whereas yohimbine- and saline-treated lambs did not walk unassisted until 15.6 +/- 2.7 and 73.0 +/- 6.8 minutes later, respectively. Results of this study indicated that medetomidine is a potent CNS depressant in lambs.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Effects of atipamezole and yohimbine on medetomidine-induced central nervous system depression and cardiorespiratory changes in lambs. 766 59

The sedative effect of medetomidine was evaluated in 6 male Awassi sheep. Medetomidine at 40 micrograms/kg, i.m. induced sedation and recumbency in the sheep within 9 +/- 1 and 17 +/- 4 minutes, respectively. The duration of recumbency was 58 +/- 1 minutes. Medetomidine produced good analgesia and marked muscle relaxation in the recumbent animals for 30 to 45 minutes. The side effects of medetomidine were bradycardia, respiratory depression, stasis of the rumen with tympany, salivation and polyuria. The animals recovered from the sedative and side effects of medetomidine 1.5 to 2 hours after gaining the righting reflex without any apparent adverse effect. The results suggested that medetomidine could be a useful sedative analgesic in sheep.
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PMID:Medetomidine sedation in sheep. 821 47

Cardiovascular and pulmonary effects of propofol, a relatively new nonbarbiturate intravenous anaesthetic, were assessed and compared in 22 male and female dogs. Dogs in group 1 did not receive any premedication prior to 6.6 mg/kg IV propofol, group 2 was premedicated with atropine (0.02 mg/kg IM) and the alpha 2-agonist medetomidine (10 micrograms/kg IM), and group 3 received the same premedication agents as group 2, but the medetomidine effects were reversed by the alpha 2-antagonist atipamezole (30 micrograms/kg IV) after 30 min of anaesthesia. Each dog in groups 2 and 3 received a propofol induction dose of 2.2 mg/kg IV. The anaesthetic duration was shortest with propofol alone and prolonged with medetomidine as a premedication which was reversible with atipamezole. In group 1, the most prominent effects were a temporary drop in diastolic arterial blood pressure (26% and 24%) at 2 and 5 min post-propofol, respectively and a drop in respiratory frequency (41%) 2 min after propofol induction. Similar respiratory depression was observed in groups 2 and 3 (20% and 48%, respectively) at the same time. Apnea was not observed. An increase in systemic arterial blood pressure was observed throughout the trial in groups 2 and 3 until dogs recovered or were reversed with atipamezole. Medetomidine significantly reduces propofol dosage requirements. Safe and effective injectable anaesthesia was produced by propofol in this group of dogs. The frequency of respiratory depression would suggest in clinical usage, the practitioner should be aware oxygen supplementation is the treatment of choice should apnea occur.
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PMID:Comparative responses to propofol anaesthesia alone and with alpha 2-adrenergic medications in a canine model. 876 97

This study evaluated the quality of anaesthesia and the cardiorespiratory effects induced by the combination of medetomidine with either ketamine, propofol or fentanyl. Medetomidine premedication (1000 or 1500 micrograms/m2 body surface area) was followed by intravenous induction of anaesthesia with ketamine (3.0 mg/kg), propofol (2.0 mg/kg) or fentanyl (2.0 micrograms/kg) in bitches undergoing elective ovariohysterectomy. Anaesthesia was prolonged by incremental doses of the induction agents as necessary. The mean (sem) overall doses (including induction) were 0.09 (0.01) mg/kg/min for ketamine, 0.06 (0.01) mg/kg/min for propofol and 0.07 (0.005) microgram/kg/min for fentanyl during procedures which lasted 88 (6) minutes, 72 (3) minutes and 79 (7) minutes, respectively. At the end of the procedure, medetomidine was antagonised with atipamezole. The quality of anaesthesia, heart rate and arterial blood pressure were recorded continuously and arterial blood gases were measured at intervals. At the end of the procedure, the animals received 10 micrograms/kg buprenorphine intramuscularly for postoperative analgesia. From the adequacy of anaesthesia, the lack of significant adverse side effects and the reliable and rapid recovery it is concluded that, in healthy dogs anaesthetised with ketamine or propofol, medetomidine is a satisfactory sedative-analgesic premedicant. The differences in haemodynamics and the quality of recovery suggest that the combination of medetomidine with propofol provided the better quality anaesthesia. The combination of medetomidine with fentanyl was unsuitable for obtaining surgical anaesthesia in spontaneously breathing animals owing to the severity of the respiratory depression at dosages needed for general anaesthesia.
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PMID:Medetomidine as a premedicant for ketamine, propofol or fentanyl anaesthesia in dogs. 918 10

This study was carried out in order to evaluate the analgesic, sedative, immobilizing and cardiopulmonary effects of medetomidine in goats after lumbosacral epidural injection of three (10, 20 and 30 micrograms/kg body weight) doses. The volume of the injection for all three medetomidine doses was 5 ml in sterile water. Seventeen clinically healthy, Small East African goats of either sex and weighing between 12 and 22 kg (mean +/- SD; 14.8 +/- 2.5 kg body weight) were used. The animals were randomly assigned to two groups. Seven goats were used for evaluating analgesic, behavioural and cardiopulmonary effects while 10 were used for experimental surgery. The cardiopulmonary values and rectal temperature were determined and recorded at time 0 (preinjection) and at 5, 10, 15, 20 and 30 min, and thereafter at 15-min intervals up to 180 min after injection. Analgesia of the flank and perineum was determined at time 0 (preinjection) and at 5, 10, 15, 30, 60, 120 and 180 min using a scoring system. The spread of analgesia to the thorax, neck, forelimbs and head was also determined and recorded. The onset and duration of lateral recumbency was noted and recorded. Medetomidine at the given doses induced variable cardiopulmonary depression, which was not detrimental to the animals. All three doses (10, 20 and 30 micrograms/kg) of medetomidine induced adequate analgesia of the flank and perineum. Analgesia extended to the thorax, forelimbs, neck and head. The duration of lateral recumbency was 136 and 166 min for the 20 and 30 micrograms/kg medetomidine doses, respectively. The duration of lateral recumbency was not determined for the animal given 10 micrograms/kg medetomidine. Signs of sedation (lowering of the head, drooping of the lower lip, partial to complete closure of the eyes and salivation) were noted after administration of all three doses. It can be concluded from this study that all three doses induced adequate analgesia of the flank and perineum. Surgical analgesia of the flank of goats was achieved after lumbosacral epidural administration of 20 micrograms medetomidine/kg, diluted in 5 ml of sterile water. Surgery was not performed with the other doses (10 and 30 micrograms/kg) of medetomidine.
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PMID:Analgesic, behavioural and cardiopulmonary effects of epidurally injected medetomidine (Domitor) in goats. 1080 5

The cardiovascular effects of medetomidine, detomidine, and xylazine in horses were studied. Fifteen horses, whose right carotid arteries had previously been surgically raised to a subcutaneous position during general anesthesia were used. Five horses each were given the following 8 treatments: an intravenous injection of 4 doses of medetomidine (3, 5, 7.5, and 10 microg/kg), 3 doses of detomidine (10, 20, and 40 microg/kg), and one dose of xylazine (1 mg/kg). Heart rate decreased, but not statistically significant. Atrio-ventricular block was observed following all treatments and prolonged with detomidine. Cardiac index (CI) and stroke volume (SV) were decreased with all treatments. The CI decreased to about 50% of baseline values for 5 min after 7.5 and 10 microg/kg medetomidine and 1 mg/kg xylazine, for 20 min after 20 microg/kg detomidine, and for 50 min after 40 microg/kg detomidine. All treatments produced an initial hypertension within 2 min of drug administration followed by a significant decrease in arterial blood pressure (ABP) in horses administered 3 to 7.5 microg/kg medetomidine and 1 mg/kg xylazine. Hypertension was significantly prolonged in 20 and 40 microg/kg detomidine. The hypotensive phase was not observed in 10 microg/kg medetomidine or detomidine. The changes in ABP were associated with an increase in peripheral vascular resistance. Respiratory rate was decreased for 40 to 120 min in 5, 7.5, and 10 microg/kg medetomidine and detomidine. The partial pressure of arterial oxygen decreased significantly in 10 microg/kg medetomidine and detomidine, while the partial pressure of arterial carbon dioxide did not change significantly. Medetomidine induced dose-dependent cardiovascular depression similar to detomidine. The cardiovascular effects of medetomidine and xylazine were not as prolonged as that of detomidine.
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PMID:Cardiovascular effects of medetomidine, detomidine and xylazine in horses. 1107 71

Dogs were given medetomidine (10 microg/kg body weight, intramuscularly) followed in 10 minutes by either ketamine (4 mg/kg body weight, intravenously) or isoflurane mask induction and maintained on isoflurane for 30 minutes. Medetomidine induced lateral recumbency in all dogs. Endotracheal intubation was faster and smoother when dogs were given ketamine than when induced with isoflurane. Analgesia was excellent in all groups. Respiratory depression was more profound when dogs were given ketamine. Recovery quality was smooth and similar among all groups. Medetomidine-premedicated dogs could be induced with either ketamine or isoflurane and maintained on 1.3% isoflurane to achieve good analgesia with smooth recovery from anesthesia.
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PMID:Anesthetic effects of ketamine or isoflurane induction prior to isoflurane anesthesia in medetomidine-premedicated dogs. 1156 39

Medetomidine is a relatively new sedative analgesic drug that is approved for use in dogs in Canada. It is the most potent alpha2-adrenoreceptor available for clinical use in veterinary medicine and stimulates receptors centrally to produce dose-dependent sedation and analgesia. Significant dose sparing properties occur when medetomidine is combined with other anesthetic agents correlating with the high affinity of this drug to the alpha2-adrenoreceptor. Hypoventilation occurs with medetomidine sedation in dogs; however, respiratory depression becomes most significant when given in combination with other sedative or injectable agents. The typical negative cardiovascular effects produced with other alpha2-agonists (bradycardia, bradyarrhythmias, a reduction in cardiac output, hypertension +/- hypotension) are also produced with medetomidine, warranting precautions when it is used and necessitating appropriate patient selection (young, middle-aged healthy animals). While hypotension may occur, sedative doses of medetomidine typically raise the blood pressure, due to the effect on peripheral alpha2-adrenoreceptors. Anticholinergic premedication has been recommended with alpha2-agonists to prevent bradyarrhythmias and, potentially, the reduction in cardiac output produced by these agents; however, current research does not demonstrate a clear improvement in cardiovascular function. Negatively, the anticholinergic induced increase in heart rate potentiates the alpha2-agonist mediated hypertension and may increase myocardial oxygen tension, demand, and workload. Overall, reversal with the specific antagonist atipamezole is recommended when significant cardiorespiratory complications occur. Other physiological effects of medetomidine sedation include; vomiting, increased urine volumes, changes to endocrine function and uterine activity, decreased intestinal motility, decreased intraocular pressure and potentially hypothermia, muscle twitching, and cyanosis. Decreased doses of medetomidine, compared with the recommended label dose, should be considered in combination with other sedatives to enhance sedation and analgesia and lower the duration and potential severity of the negative cardiovascular side effects. The literature was searched in Pubmed, Medline, Agricola, CAB direct, and Biological Sciences.
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PMID:A review of the physiological effects of alpha2-agonists related to the clinical use of medetomidine in small animal practice. 1466 51


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