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1.
OBJECTIVE: To review the use and adverse effects of alpha(2)-agonists in sheep. STUDY DESIGN: Literature review. MATERIAL AND METHODS: 'Pubmed' of the United States National Library of Medicine and 'Veterinary Science' of CAB International were searched for references relating sheep to alpha(2)-agonists. The bibliographies of retrieved articles were further scrutinized for pertinent references, and relevant articles were selected manually. RESULTS: Reports on the use of clonidine, xylazine, detomidine, romifidine, medetomidine and dexmedetomidine, MPV-2426 and ST-91 in sheep were found in the literature. Most of the studies described xylazine followed by medetomidine and clonidine. The literature on detomidine and romifidine in sheep was sparse. Reports included pharmacokinetic studies, evaluation of sedative, analgesic, and anaesthetic techniques with or without cardiovascular effects, and experimental investigations of adverse effects (mainly hypoxaemia) including the mechanisms of pulmonary oedema and impaired oxygenation after alpha(2)-agonist administration. CONCLUSIONS: A(2)-agonists are potent and effective analgesics in sheep. In combination with ketamine, they are frequently used for the induction and maintenance of anaesthesia, in this case analgesia is satisfactory. The degree of hypoxaemia which occurs with all commercially available alpha(2)-agonists is highly variable and depends on individual or breed-related factors; the most severe reactions occur after intravenous (IV) injection and during general anaesthesia. Clinical relevance Subclinical respiratory disease is common in sheep. Rapid IV injection of alpha(2)-agonists without supplementary oxygen should be avoided whenever hypoxaemia may be critical.  相似文献   

2.
We compared the ability of tolazoline and yohimbine to antagonize xylazine-induced central nervous system depression, bradycardia, and tachypnea in 9 ewes and 5 rams. Once a week for 3 weeks, each sheep received one IV treatment of 0.4 mg xylazine/kg, 0.4 mg xylazine/kg followed in 10 minutes by 2 mg tolazoline/kg, or 0.4 mg xylazine/kg followed in 10 minutes by 0.2 mg yohimbine/kg. The order of the 3 treatments in each sheep was randomized. Xylazine alone caused recumbency for 41.0 +/- 3.7 minutes (mean +/- SEM). Tolazoline and yohimbine shortened the xylazine-induced recumbency to 12.1 +/- 0.9 minutes and 18.1 +/- 1.5 minutes, respectively. Sheep given xylazine alone had head droop for 34.0 +/- 5.4 minutes after rising. Head drooping of sheep given tolazoline or yohimbine was reduced to 10.1 +/- 1.7 minutes and 14.2 +/- 1.7 minutes, respectively. Both tolazoline and yohimbine reversed the bradycardia and tachypnea that followed xylazine administration. No statistical differences in the rate and magnitude of the reversal were observed between the 2 drugs.  相似文献   

3.
Alterations in parasympathetic tone are partially responsible for xylazine's hemodynamic effects. The purpose of this study was to evaluate and compare the hemodynamic changes caused by the administration of intravenous (IV) atropine or glycopyrrolate after IV xylazine in isoflurane-anesthetized dogs. Six healthy beagles (8.2 to 10.7 kg) were used in two trials separated by 7 days. Anesthesia was induced and maintained with isoflurane in 100% oxygen with controlled ventilation. Once constant end-tidal isoflurane (1.8%) and arterial partial pressure of carbon dioxide (35 to 45 mm Hg) values were reached, baseline data were recorded and xylazine (0.5 mg/kg, IV) was given. In trial 1 atropine (0.1 mg/kg, IV) was given 5 minutes after xylazine, and in trial 2 glycopyrrolate (0.025, mg/kg, IV), was given 5 minutes after xylazine. Hemodynamic variables were recorded 3 minutes after xylazine and 3 minutes after anticholinergic administration. In trial 2, bilateral vagotomies were performed 10 minutes after glycopyrrolate, and hemodynamic variables were recorded 3 minutes later. Heart rate, cardiac index, and stroke index decreased; arterial pressure and systemic vascular resistance increased after xylazine. Heart rate, cardiac index, and rate pressure product increased after anticholinergic administration. Significant differences between atropine and glycopyrrolate were not observed in any of the hemodynamic parameters. Similarly, significant differences between glycopyrrolate and bilateral vagotomy were not observed. The authors conclude that intravenous atropine and glycopyrrolate have equivalent hemodynamic actions during the increased pressure phase after IV xylazine in isoflurane-anesthetized dogs; that intravenous atropine and glycopyrrolate produce comparable increases in heart rate and that both may increase the risk of myocardial hypoxia associated with an increase in rate pressure product; and that vagal blockade produced by high-dose glycopyrrolate (.025 mg/kg, IV) is similar to that produced by bilateral vagotomy.  相似文献   

4.
Xylazine and tiletamine-zolazepam anesthesia in horses   总被引：4，自引：0，他引：4  
The cardiopulmonary and anesthetic effects of xylazine in combination with a 1:1 mixture of tiletamine and zolazepam were determined in 6 horses. Each horse was given xylazine IV or IM, as well as tiletamine-zolazepam IV on 4 randomized occasions. Anesthetics were administered at the rate of 1.1 mg of xylazine/kg of body weight, IV, 1.1 mg of tiletamine-zolazepam/kg, IV (treatment 1); 1.1 mg of xylazine/kg, IV, 1.65 mg of tiletamine-zolazepam/kg, IV (treatment 2); 1.1 mg of xylazine/kg, IV, 2.2 mg of tiletamine-zolazepam/kg, IV (treatment 3); and 2.2 mg of xylazine/kg, IM, 1.65 mg of tiletamine-zolazepam/kg, IV (treatment 4). Tiletamine-zolazepam doses were the sum of tiletamine plus zolazepam. Xylazine, when given IV, was given 5 minutes before tiletamine-zolazepam. Xylazine, when given IM, was given 10 minutes before tiletamine-zolazepam. Tiletamine-zolazepam induced recumbency in all horses. Duration of recumbency in group 1 was 31.9 +/- 7.2 (mean +/- 1 SD) minutes. Increasing the dosage of tiletamine-zolazepam (treatments 2 and 3) significantly (P less than 0.05) increased the duration of recumbency. Xylazine caused significant (P less than 0.05) decreases in heart rate and cardiac output and significant (P less than 0.05) increases in central venous pressure and mean pulmonary artery pressure 5 minutes after administration. Respiratory rate was decreased. Arterial blood pressures increased significantly (P less than 0.05) after xylazine was administered IV in treatments 1 and 3, but the increases were not significant in treatment 2. Xylazine administered IM caused significant (P less than 0.05) increases in central venous pressure and significant (P less than 0.05) decreases in cardiac output.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

5.
Effects of ketamine, xylazine, and a combination of ketamine and xylazine were studied in 12 male Pekin ducks (7 to 12 weeks old; mean [+/- SD] body weight, 3.1 +/- 0.3 kg). After venous and arterial catheterization and fixation of a temperature probe in the cloaca, each awake duck was confined, but not restrained, in an open box in a dimly lit room. Blood pressure and lead-II ECG were recorded. Three arterial blood samples were collected every 15 minutes over a 45-minute period (control period) and were analyzed for pHa, PaCO2 and PaO2. After the control period, each duck was assigned at random to 1 of 3 drug groups: (1) ketamine (KET; 20 mg/kg of body weight, IV), (2) xylazine (XYL; 1 mg/kg, IV), and (3) KET + XYL (KET 20 mg/kg and XYL, 1 mg/kg; IV). Measurements were made at 1, 5, 10, 15, 30, 45, 60, and 90 minutes after drug administration. All ducks survived the drug study. Cloacal temperature was significantly (P less than or equal to 0.05) increased above control cloacal temperature at 90 minutes after the administration of ketamine, and from 10 through 90 minutes after administration of ketamine plus xylazine. In ducks of the KET group, pHa, PaCO2, and PaO2, remained unchanged after administration of the drug. In ducks of the XYL group, pHa and PaO2 decreased significantly (P less than or equal to 0.05) from control values for all time points up to and including 15 minutes after drug administration.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

6.
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   

7.
Lumbosacral CSF pressure was measured in 6 horses via a catheter inserted through the lumbosacral space. Heart rate, facial artery pressure, central venous pressure, and CSF pressure were measured before IV injection of a saline solution control, for 15 minutes after saline solution injection, and for 60 minutes after the IV injection of 1.1 mg of xylazine/kg of body weight. Arterial pH and blood gases were analyzed before saline solution injection, 15 minutes after saline solution injection, and at 15, 30, and 60 minutes after xylazine injection. Constant craniocervical posture was maintained during sedation. Lumbosacral CSF pressure was significantly decreased for 15 minutes after xylazine injection. Diastolic arterial pressure was significantly increased 4 minutes after xylazine administration and diastolic and mean arterial pressure were increased at 6 and 8 minutes after xylazine administration. Small increases in systolic arterial blood pressure and central venous pressure, and a small decrease in heart rate were observed. There were no significant differences in the arterial blood gas values. It was concluded that IV injection of xylazine causes a decrease in intracranial pressure in healthy conscious horses. The effects may be different in horses with neurologic disease or cerebral trauma.  相似文献   

8.
OBJECTIVE: To determine cardiorespiratory effects of a tiletamine/zolazepam-ketamine-detomidine (TZKD) combination in horses. ANIMALS: 8 healthy adult horses. PROCEDURE: Horses were instrumented for measurement of cardiorespiratory, acid-base, and electrolyte values. Each horse was given xylazine (0.44 mg/kg of body weight, IV) 10 to 15 minutes prior to induction of recumbency by administration of the TZKD combination. Cardiorespiratory, acid-base, and electrolyte values were measured at 5-minute intervals for > or =30 minutes. RESULTS: All horses became recumbent within 1 minute after IV administration of TZKD. Mean +/- SD duration of recumbency was 40+/-8 minutes. All horses regained standing position after < or =2 attempts. Quality of anesthesia and analgesia was determined to be satisfactory in all horses. Xylazine induced decreases in respiratory rate, heart rate, cardiac output, maximum rate of increase of right ventricular pressure, and rate pressure product. The PaCO2, right atrial pressure, and peripheral vascular resistance increased, whereas blood temperature, PO2, pHa, HCO3-, PCV, total solids, Na, and K values remained unchanged. Subsequent administration of TZKD caused right atrial pressure and PaCO2 to increase and PaO2 to decrease, compared with values obtained after xylazine administration. Remaining cardiorespiratory, acid-base, hematologic, and electrolyte values did not differ from those obtained after xylazine administration. CONCLUSION: IV administration of TZKD induces short-term anesthesia in horses. Potential advantages of this drug combination are the small volume of drug administered; minimal cardiorespiratory depression; quality of induction and maintenance of, and recovery from, anesthesia; and duration of drug effects.  相似文献   

9.
Mechanical activity of the cecal body, lateral cecal arterial blood flow, carotid arterial pressure, and heart rate were measured in 6 conscious healthy horses 30 minutes before and for 120 minutes after IV administration of xylazine at dosages of 1.1 mg/kg of body weight, 0.55 mg/kg, and 0.275 mg/kg. Xylazine at a dosage of 1.1 mg/kg reduced the mean motility index (the product of the mean amplitude of contractions and the total duration of contractile activity divided by the recording time) of the circular and longitudinal muscle layers for the first, second, third, and fourth 30-minute periods after administration of xylazine. Xylazine at a dosage of 0.55 mg/kg reduced the motility index of the circular and longitudinal muscle layers for the first and second 30-minute periods after administration of xylazine. Xylazine at a dosage of 0.275 mg/kg reduced the motility index of the circular and longitudinal muscle layers for the first 30-minute period after administration of xylazine. Mean lateral cecal arterial blood flow was significantly (P less than 0.05) lower than the base-line value at 2 and 4 minutes after administration of all 3 xylazine dosages and at 8 minutes after administration of xylazine dosages of 1.1 mg/kg and 0.55 mg/kg. All dosages of xylazine caused transient hypertension and bradycardia, followed by hypotension.  相似文献   

10.
The hemodynamic effects of hypertonic saline solution (HSS) resuscitation on endotoxic shock were examined in pentobarbital-anesthetized calves (8 to 20 days old). Escherichia coli (055:B5) endotoxin was infused IV at dosage of 0.1 microgram/kg of body weight for 30 minutes. Endotoxin induced large decreases in cardiac index, stroke volume, maximal rate of change of left ventricular pressure (+dP/dtmax), femoral and mesenteric arterial blood flow, glomerular filtration rate, urine production, and mean aortic pressure. Severe pulmonary arterial hypertension and increased pulmonary vascular resistance were evident at the end of endotoxin infusion. Treatment with HSS (2,400 mosm of NaCl/L, 4 ml/kg) or an equivalent sodium load of isotonic saline solution (ISS: 300 mosm of NaCl/L, 32 ml/kg) was administered 90 minutes after the end of endotoxin administration. Both solutions were infused IV over a 4- to 6-minute period. Administration of HSS induced immediate and significant (P less than 0.05) increase in stroke volume and central venous pressure, as well as significant decrease in pulmonary vascular resistance. These effects were sustained for 60 minutes, after which all variables returned toward preinfusion values. The hemodynamic response to HSS administration was suggestive of rapid plasma volume expansion and redistribution of cardiac output toward splanchnic circulation. Plasma volume expansion by HSS was minimal 60 minutes after resuscitation. Administration of ISS induced significant increase in cardiac index, stroke volume, femoral arterial blood flow, and urine production. These effects were sustained for 120 minutes, at which time, calves were euthanatized. Compared with HSS, ISS induced sustained increase in mean pulmonary arterial pressure and only a small increase in mesenteric arterial blood flow.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

11.
Serum insulin and plasma glucose concentrations were determined in 8 mares. Four IV treatments were studied: xylazine (1.1 mg/kg of body weight); yohimbine (0.125 mg/kg); yohimbine (0.125 mg/kg) followed 5 minutes later by xylazine (1.1 mg/kg); and 5 ml of isotonic saline solution as a control. Blood samples were collected before (time 0) and at 5, 15, 30, 60, 120, and 180 minutes after drug administration. Serum insulin concentration decreased and plasma glucose concentration increased in mares given xylazine. Plasma glucose concentration was unchanged in control mares and in mares given yohimbine or yohimbine followed by xylazine. Serum insulin concentration was unchanged in mares given saline solution, but transiently increased in mares given yohimbine alone. Treatment with yohimbine prevented xylazine-induced hypoinsulinemia and hyperglycemia.  相似文献   

12.
OBJECTIVE: To determine the cardiopulmonary and sedative effects of medetomidine hydrochloride in adult horses and to compare those effects with effects of an equipotent dose of xylazine hydrochloride. ANIMALS: 10 healthy adult female horses. PROCEDURE: 5 horses were given medetomidine (4 microg/kg of body weight, i.v.), and the other 5 were given xylazine (0.4 mg/kg, i.v.). Heart rate, respiratory rate, arterial blood pressures, pulmonary arterial blood pressures, and cardiac output were recorded, and sedation and ataxia scores were assigned before and every 5 minutes after drug administration for 60 minutes. Rectal temperature and blood gas partial pressures were measured every 15 minutes after drug administration. RESULTS: Arterial blood pressure was significantly decreased throughout the study among horses given medetomidine and was significantly decreased for 40 minutes among horses given xylazine. Compared with baseline values, cardiac output was significantly decreased 10, 20, and 40 minutes after administration of medetomidine and significantly increased 40 and 60 minutes after administration of xylazine. Despite the significant decrease in respiratory rate in both groups, results of blood gas analyses were not significantly changed over time. Ataxia and sedation scores were of similar magnitude for the 2 groups, but ataxia persisted slightly longer among horses given medetomidine. Horses resumed eating hay 10 to 55 minutes after drug administration. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that equipotent low doses of medetomidine and xylazine induce comparable levels of ataxia and sedation and similar cardiopulmonary changes in adult horses.  相似文献   

13.
SUMMARY: Sheep were placed in right lateral recumbency for ten minutes. The arterial oxygen tension mean values in standing, lateral and three minutes after return to standing postures respectively were 81, 57 and 81 mm Hg; the arterial carbon dioxide tensions were 31, 28 and 26 mm Hg and the end-tidal oxygen tensions of pharyngeal gas were 107, 111 and 112 mm Hg.
A second study in which the sheep were sedated by xylazine 20 minutes before being placed in lateral recumbency yielded almost identical results except that the. arterial oxygen tension fell to values of 71 mm Hg in both samples taken from the standing sheep at five and 17 minutes after xylazine administration.  相似文献   

14.
OBJECTIVE: To determine effects of the selectin inhibitor TBC1269 on neutrophil-mediated pulmonary damage during acute Mannheimia haemolytica-induced pneumonia in newborn calves. ANIMALS: Eighteen 1- to 3-day-old colostrum-deprived calves. PROCEDURE: Mannheimia haemolytica or saline (0.9% NaCl) solution was inoculated in both cranial lung lobes of 12 and 6 calves, respectively. Calves were euthanatized 2 (saline, n = 3; M haemolytica, n = 4) or 6 hours (saline, n = 3; M haemolytica, n = 8) after inoculation. Four M haemolytica-inoculated calves euthanatized at 6 hours also received TBC1269 (25 mg/kg, IV) 30 minutes before and 2 hours after inoculation. Conjugated diene (CD) concentrations, inducible nitric oxide synthase (iNOS) expression, and apoptotic cell counts were determined in lung specimens collected during necropsy. RESULTS: Conjugated diene concentrations were significantly increased in all M haemolytica-inoculated groups, compared with saline-inoculated groups. Calves treated with TBC1269 had decreased concentrations of CD, compared with untreated calves, although the difference was not significant. Number of apoptotic neutrophils and macrophages increased significantly inTBC1269-treated calves, compared with untreated calves. Inducible nitric oxide synthase was expressed by epithelial cells and leukocytes. However, iNOS was less abundant in airway epithelial cells associated with inflammatory exudates. Degree of iNOS expression was similar between TBC1269-treated and untreated calves. CONCLUSIONS: Mannheimia haemolytica infection in neonatal calves resulted in pulmonary tissue damage and decreased epithelial cell iNOS expression. The selectin inhibitor TCB1269 altered, but did not completely inhibit, neutrophil-mediated pulmonary damage.  相似文献   

15.
Antagonism of xylazine-pentobarbital anesthesia by yohimbine in ponies   总被引：1，自引：0，他引：1  
Effects of yohimbine on xylazine-pentobarbital anesthesia were evaluated in ponies. Five minutes after the IV injection of xylazine (1.1 mg/kg of body weight), pentobarbital sodium (12.7 mg/kg, IV) and additional xylazine (2.2 mg/kg, IM) were given and produced anesthesia in 12 ponies for 64.0 +/- 16.4 minutes (mean +/- SD) as well as immobilization for 89.8 +/- 34.2 minutes. Eleven ponies were given yohimbine (0.1 mg/kg, IV) 50 minutes after pentobarbital dosing. In these 11 ponies, durations of anesthesia and immobilization were shorter, 52.0 +/- 1.4 and 65.5 +/- 14.8 minutes, respectively. The xylazine-pentobarbital combination caused bradycardia that was reversed by yohimbine injection. Xylazine-pentobarbital produced a small, but steady, decrease of mean arterial blood pressure, which was compounded by yohimbine administration and was evident for approximately 2 minutes. Within a minute after yohimbine injection, the ponies' respiratory rate decreased and the length of inspiration and expiration and thoracic breathing increased. This lasted approximately 2 to 3 minutes and was followed by an increase in respiratory rate. The anesthesia also produced a decrease in PaO2 that gradually returned to base line in 12 control ponies, but was more pronounced in 11 ponies given yohimbine. The PaCO2, although remaining moderately high in control ponies, returned to base line after yohimbine injection. An increased pHa was seen 60 minutes after induction of anesthesia and was especially noticeable after yohimbine administration. Decreases in the number of WBC, hemoglobin content, PCV, plasma protein and serum aspartate transaminase resulting from xylazine-pentobarbital were reversed by yohimbine. Conversely, serum glucose values and creatine kinase activities were increased by xylazine-pentobarbital.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

16.
The effect of xylazine on the arrhythmogenic dose of epinephrine (ADE) was studied in 9 horses. Anesthesia was induced by administration of guaifenesin (50 mg/kg of body weight, IV) followed by thiamylal (4 to 6 mg/kg, IV) and was maintained at 1 minimal alveolar concentration (MAC) of halothane (0.89%). Base apex ECG and facial artery pressure were recorded. Epinephrine was infused in a sequence of arithmetically spaced increasing rates (initial rate 0.25 micrograms/kg/min) for a maximum of 10 minutes. The ADE was defined as the lowest epinephrine infusion rate to the nearest 0.25 micrograms/kg/min at which at least 4 premature ventricular depolarizations occurred in a 15-second period. Xylazine (1.1 mg/kg, IV) was administered after the control ADE was determined. Xylazine did not significantly alter the ADE (control, 1.12 +/- 0.38 micrograms/kg/min; xylazine, 1.21 +/- 0.46 micrograms/kg/min). Blood pressure increased transiently for 8 minutes after xylazine administration. Baseline systolic and diastolic arterial pressures and heart rate were not significantly different from control baseline pressures and heart rate 15 minutes after xylazine administration. Blood pressure and heart rate increased significantly during control and xylazine ADE determinations. Significant differences in pH, PaO2, PaCO2, or base excess were not observed between baseline and ADE in the control or xylazine groups. One horse developed atrial fibrillation, and 2 horses developed ventricular fibrillation during ADE determinations.  相似文献   

17.
ObjectivesTo investigate the extent of vatinoxan distribution into sheep brain, and whether vatinoxan influences brain concentrations of xylazine; and to examine the utility of cerebrospinal fluid (CSF) as a surrogate of brain tissue concentrations for vatinoxan and xylazine.Study designRandomised, blinded, experimental study.AnimalsA total of 14 adult female sheep.MethodsSheep were randomly allocated into two equal groups and premedicated with either intravenous (IV) vatinoxan (750 μg kg–1, VX) or saline (SX) administered 10 minutes before IV xylazine (500 μg kg–1). Sedation was subjectively assessed at selected intervals before and after treatments. At 10 minutes after xylazine administration, a venous blood sample was collected and the sheep were immediately euthanised with IV pentobarbital (100 mg kg–1). Plasma, CSF and brain tissues were harvested, and concentrations of vatinoxan and xylazine were quantified using liquid chromatography–tandem mass spectrometry. Drug ratios were then calculated and the data were analysed as appropriate.ResultsThe brain-to-plasma and CSF-to-plasma ratios of vatinoxan were 0.06 ± 0.013 and 0.05 ± 0.01 (mean ± standard deviation), respectively. Xylazine brain concentrations were not significantly different (835 ± 262 versus 1029 ± 297 ng g–1 in groups VX and SX, respectively) and were approximately 15-fold higher than those in plasma. The CSF-to-brain ratio of vatinoxan was 0.8 ± 0.2, whereas xylazine concentrations in the brain were approximately 17-fold greater than those in CSF, with and without vatinoxan.Conclusions and clinical relevanceVatinoxan did not significantly affect sedation with xylazine or the concentrations of xylazine in the brain. CSF is not a good predictor of xylazine concentrations in the brain, whereas vatinoxan concentrations were concordant between the brain and CSF, using the dosages in this study.  相似文献   

18.
The acoustic reflex (AR) and brain stem auditory-evoked response (BAER) were recorded in adult cats 5 minutes after IM administration of xylazine (1 mg/kg) and after IM administration of ketamine (10 mg/kg). Ipsilateral and contralateral AR were recorded at 10 and 20 dB above acoustic reflex threshold 5 minutes after xylazine administration and 5 and 35 minutes after ketamine administration. Monaural BAER were recorded 5 minutes after xylazine and 5 and 35 minutes after ketamine, using stimulus intensities of 90-, 80-, and 70-dB hearing level (HL). Additional BAER were recorded at 10, 15, and 25 minutes after ketamine, using the 90-dB HL stimulus. Pre- and postinjection comparisons were made for threshold, latency, and amplitude of the AR and for latency and amplitude of waves I through VI of the BAER. At both stimulus intensities before and after ketamine administration threshold for the ipsilateral reflex was significantly lower (P greater than 0.05) than for the contralateral reflex. The threshold, latency, and amplitude of the AR were unaffected (P greater than 0.05) by the injection of ketamine after xylazine. The amplitude of BAER waves was not affected (P greater than 0.05) by ketamine after xylazine for each of the 3 stimulus intensities. Latency of the 90-dB HL-evoked response was increased (P less than or equal to 0.05) for waves III/IV at 5 and 35 minutes after ketamine, and for wave V at each of the postinjection times, except at postinjection minute 15.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

19.
OBJECTIVE: To evaluate sevoflurane as an inhalation anesthetic for thoracotomy in horses. ANIMALS: 18 horses between 2 and 15 years old. PROCEDURE: 4 horses were used to develop surgical techniques and were euthanatized at the end of the procedure. The remaining 14 horses were selected, because they had an episode of bleeding from their lungs during strenuous exercise. General anesthesia was induced with xylazine (1.0 mg/kg of body weight, IV) followed by ketamine (2.0 mg/kg, IV). Anesthesia was maintained with sevoflurane in oxygen delivered via a circle anesthetic breathing circuit. Ventilation was controlled to maintain PaCO2 at approximately 45 mm Hg. Neuromuscular blocking drugs (succinylcholine or atracurium) were administered to eliminate spontaneous breathing efforts and to facilitate surgery. Cardiovascular performance was monitored and supported as indicated. RESULTS: 2 of the 14 horses not euthanatized died as a result of ventricular fibrillation. Mean (+/- SD) duration of anesthesia was 304.9 +/- 64.1 minutes for horses that survived and 216.7 +/- 85.5 minutes for horses that were euthanatized or died. Our subjective opinion was that sevoflurane afforded good control of anesthetic depth during induction, maintenance, and recovery. CONCLUSIONS AND CLINICAL RELEVANCE: Administration of sevoflurane together with neuromuscular blocking drugs provides stable and easily controllable anesthetic management of horses for elective thoracotomy and cardiac manipulation.  相似文献   

20.
The effects of yohimbine (0.125 mg/kg) on cardiopulmonary parameters in six adult, xylazine treated (0.15 mg/kg), laterally recumbent sheep were studied. Following collection of baseline data, xylazine was administered intravenously and data were collected five and fifteen minutes later. At twenty minutes post-xylazine either yohimbine (0.125 mg/kg) or saline was given and further collection of data occurred at 25, 30, 40 and 50 minutes. Xylazine administration resulted in significant (P less than 0.05) respiratory depression, as reflected by a decrease in arterial oxygen partial pressure (PaO2). No significant changes in haemodynamic variables were observed. Yohimbine produced a significant improvement in PaO2 at the 50 minute period and abolished the paradoxical respiratory pattern when present. The results indicated that yohimbine can be used as an antagonist to control the duration of xylazine induced respiratory depression, although the degree of reversal was less than is clinically desirable.  相似文献   

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