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1.
OBJECTIVE: To determine the effects of constant rate infusion of morphine, lidocaine, ketamine, and morphine-lidocaine-ketamine (MLK) combination on end-tidal isoflurane concentration (ET-Iso) and minimum alveolar concentration (MAC) in dogs anesthetized with isoflurane and monitor depth of anesthesia by use of the bispectral index (BIS). ANIMALS: 6 adult dogs. PROCEDURE: Each dog was anesthetized with isoflurane on 5 occasions, separated by a minimum of 7 to 10 days. Individual isoflurane MAC values were determined for each dog. Reduction in isoflurane MAC, induced by administration of morphine (3.3 microg/kg/min), lidocaine (50 microg/kg/min), ketamine (10 microg/kg/min), and MLK, was determined. Heart rate, mean arterial blood pressure, oxygen saturation as measured by pulse oximetry (Spo2), core body temperature, and BIS were monitored. RESULTS: Mean +/- SD isoflurane MAC was 1.38 +/- 0.08%. Morphine, lidocaine, ketamine, and MLK significantly lowered isoflurane MAC by 48, 29, 25, and 45%, respectively. The percentage reductions in isoflurane MAC for morphine and MLK were not significantly different but were significantly greater than for lidocaine and ketamine. The Spo2, mean arterial pressure, and core body temperature were not different among groups. Heart rate was significantly decreased at isoflurane MAC during infusion of morphine and MLK. The BIS was inversely related to the ET-Iso and was significantly increased at isoflurane MAC during infusions of morphine and ketamine, compared with isoflurane alone. CONCLUSIONS AND CLINICAL RELEVANCE: Low infusion doses of morphine, lidocaine, ketamine, and MLK decreased isoflurane MAC in dogs and were not associated with adverse hemodynamic effects. The BIS can be used to monitor depth of anesthesia.  相似文献   

2.
REASONS FOR PERFORMING STUDY: Lidocaine constant rate infusions (CRIs) are common as an intraoperative adjunct to general anaesthesia, but their influence on quality of recovery has not been thoroughly determined. OBJECTIVES: To determine the effects of an intraoperative i.v. CRI of lidocaine on the quality of recovery from isoflurane or sevoflurane anaesthesia in horses undergoing various surgical procedures, using a modified recovery score system. HYPOTHESIS: The administration of intraoperative lidocaine CRI decreases the quality of recovery in horses. METHODS: Lidocaine (2 mg/kg bwt bolus followed by 50 microg/kg bwt/min) or saline was administered for the duration of surgery or until 30 mins before the end of surgery under isoflurane (n = 27) and sevoflurane (n = 27). RESULTS: Horses receiving lidocaine until the end of surgery had a significantly higher degree of ataxia and a tendency towards significance for a lower quality of recovery. There was no correlation between lidocaine plasma concentrations at recovery and the quality of recovery. CONCLUSIONS: Intraoperative CRI of lidocaine affects the degree of ataxia and may decrease the quality of recovery. POTENTIAL RELEVANCE: Discontinuing lidocaine CRI 30 mins before the end of surgery is recommended to reduce ataxia during the recovery period.  相似文献   

3.
Reasons for performing study: Lidocaine single boluses and/or constant rate infusions are commonly administered intraoperatively during inhalant anaesthesia to lower inhalant concentrations, promote or maintain gastrointestinal motility, and potentially supplement analgesia. The benefits of using lidocaine with injectable anaesthesia for field surgeries has not been fully explored to determine advantages and disadvantages of lidocaine as an anaesthetic and analgesic adjunct in these conditions and impact on recovery quality. Objectives: To evaluate the use of systemic lidocaine with a standard field injectable anaesthetic protocol related to the need for additional drug administration as well as overall recovery score and quality. Hypothesis: The administration of systemic lidocaine with xylazine‐diazepam/ketamine anaesthesia for castration in the field decreases the need for additional injectable doses required for maintenance, but prolong and potentially impact the overall recovery score and quality in horses. Methods: Thirty client‐owned horses underwent standard injectable anaesthesia for field castration. Fifteen horses received lidocaine 3 mg/kg bwt, i.v. as a single bolus, and 15 received saline equal volume. The horses were monitored for the need for additional injectable anaesthetics and scored for overall recovery and quality by a blinded anaesthetist. Results: There were no statistically significant differences in the overall recovery score and quality, or need for additional injectable anaesthetic between horses receiving lidocaine and those receiving saline. There was a significantly longer time for the horses to stand after induction in the lidocaine group (mean 30.7 min) vs. saline group (mean 22.5 min) (P<0.04). Conclusions: Lidocaine, 3 mg/kg bwt i.v., does not adversely affect recovery using injectable field regimes, but the overall recovery period was longer. Lidocaine does not appear to reduce the need for additional injectable administration during surgery. Potential relevance: Further research is warranted to define the benefit of systemic lidocaine with field anaesthesia in horses by exploring the ideal dose and plasma level of lidocaine with injectable anaesthesia.  相似文献   

4.
REASONS FOR PERFORMING STUDY: Recovery from inhalant anaesthesia in the horse is a critical and difficult period to manage; however, several factors could help to obtain a calm recovery period including choice of anaesthetic and analgesic procedure used and the conditions under which anaesthetic maintenance and recovery occur. OBJECTIVES: The objective of this study was to evaluate and compare the quality of recovery in horses administered saline, xylazine, detomidine or romifidine during recovery from isoflurane anaesthesia. METHODS: Six mature and healthy horses were premedicated with i.v. xylazine and butorphanol, and anaesthesia induced using ketamine. After 2 h of inhalant anaesthesia with isoflurane vaporised in oxygen, saline solution, xylazine (0.1 mg/kg bwt), detomidine (2 microg/kg bwt) or romifidine (8 pg/kg bwt) were administered. The quality of recovery of each horse and the degree of sedation and ataxia were evaluated. Cardiovascular and respiratory parameters were recorded, and arterial blood samples obtained and analysed for pH, PO2 and PCO2 during recovery. RESULTS: Quality of recovery was better in groups treated with alpha-2 adrenergic receptors agonists, showing less ataxia. Degree of sedation was greater in the romifidine group. CONCLUSIONS: We concluded that the administration of alpha-2 adrenoceptor agonists during recovery from isoflurane anaesthesia in horses prolonged and improved the quality of recovery without producing significant cardiorespiratory effects. POTENTIAL CLINICAL RELEVANCE: Administration of alpha-2 adrenoceptor agonists after inhalent anaesthesia could prevent complications during the recovery period.  相似文献   

5.
Reasons for performing study: The effects of lidocaine combined with medetomidine or lidocaine alone on cardiovascular function during anaesthesia and their effects on recovery have not been thoroughly investigated in isoflurane‐anaesthetised horses. Objectives: To determine the effects of an intraoperative i.v. constant rate infusion of lidocaine combined with medetomidine (Group 1) or lidocaine (Group 2) alone on cardiovascular function and on the quality of recovery in 12 isoflurane‐anaesthetised horses undergoing arthroscopy. Hypothesis: The combination would depress cardiovascular function but improve the quality of recovery when compared to lidocaine alone in isoflurane‐anaesthetised horses. Methods: Lidocaine (2 mg/kg bwt i.v. bolus followed by 50 µg/kg bwt/min i.v.) or lidocaine (same dose) and medetomidine (5 µg/kg bwt/h i.v.) was started 30 min after induction of anaesthesia. Lidocaine administration was discontinued 30 min before the end of surgery in both groups, whereas medetomidine administration was continued until the end of surgery. Cardiovascular function and quality of recovery were assessed. Results: Horses in Group 1 had longer recoveries, which were of better quality due to better strength and overall attitude during the recovery phase than those in Group 2. Arterial blood pressure was significantly higher in Group 1 than in Group 2 and this effect was associated with medetomidine. No significant differences in cardiac output, arterial blood gases, electrolytes and acid‐base status were detected between the 2 groups. Conclusions and potential relevance: The combination of an intraoperative constant rate infusion of lidocaine and medetomidine did not adversely affect cardiovascular function in isoflurane‐anaesthetised horses and improved the quality of recovery when compared to an intraoperative infusion of lidocaine alone.  相似文献   

6.
OBJECTIVE: To evaluate the effects of ketamine, magnesium sulfate, and their combination on the minimum alveolar concentration (MAC) of isoflurane (ISO-MAC) in goats. ANIMALS: 8 adult goats. PROCEDURES: Anesthesia was induced with isoflurane delivered via face mask. Goats were intubated and ventilated to maintain normocapnia. After an appropriate equilibration period, baseline MAC (MAC(B)) was determined and the following 4 treatments were administered IV: saline (0.9% NaCl) solution (loading dose [LD], 30 mL/20 min; constant rate infusion [CRI], 60 mL/h), magnesium sulfate (LD, 50 mg/kg; CRI, 10 mg/kg/h), ketamine (LD, 1 mg/kg; CRI, 25 microg/kg/min), and magnesium sulfate (LD, 50 mg/kg; CRI, 10 mg/kg/h) combined with ketamine (LD, 1 mg/kg; CRI, 25 microg/kg/min); then MAC was redetermined. RESULTS: Ketamine significantly decreased ISOMAC by 28.7 +/- 3.7%, and ketamine combined with magnesium sulfate significantly decreased ISOMAC by 21.1 +/- 4.1%. Saline solution or magnesium sulfate alone did not significantly change ISOMAC. CONCLUSIONS AND CLINICAL RELEVANCE: Ketamine and ketamine combined with magnesium sulfate, at doses used in the study, decreased the end-tidal isoflurane concentration needed to maintain anesthesia, verifying the clinical impression that ketamine decreases the end-tidal isoflurane concentration needed to maintain surgical anesthesia. Magnesium, at doses used in the study, did not decrease ISOMAC or augment ketamine's effects on ISOMAC.  相似文献   

7.
This study was undertaken to evaluate the effect of 3 different doses of epidurally administered morphine sulphate on the minimum alveolar concentration (MAC) of isoflurane in healthy cats. Five 4-year-old, spayed female cats weighing 4.7 ± 0.8 kg were allocated randomly to receive one of 3 doses of morphine on each study day. The 3 doses of morphine were 0.05, 0.1 and 0.2 mg/kg bwt and each cat was studied 3 times so that each cat received all doses. On each study day, cats were anaesthetised with isoflurane and instrumented. The MAC of isoflurane was determined in triplicate and morphine sulphate was administered via an epidural catheter chronically implanted prior to the study. Maximum MAC reduction was determined over the following 2 h. At the end of the study cats were allowed to recover. There was a significant reduction in MAC of isoflurane, with all doses of epidural morphine (P<0.05). The maximum reduction in MAC of isoflurane after 0.05 mg/kg bwt, 0.10 mg/kg bwt and 0.20 mg/kg bwt morphine was 21.4 ± 9.796, 30.8 ± 9.696, and 30.2 ± 6.8%, respectively, with no significant difference between doses. Systolic, mean and diastolic blood pressure, heart rate, respiratory rate and arterial pH decreased significantly whereas arterial carbon dioxide tension increased significantly after morphine administration (P<0.05). The means for all variables returned to pre-morphine values when the end-tidal isoflurane concentration was reduced to the new MAC point. In conclusion, epidural morphine decreased the concentration of isoflurane required to prevent movement in response to noxious mechanical stimulation to the tail base. A similar effect may be seen clinically allowing lower doses of isoflurane to be used to provide surgical anaesthesia for procedures involving the hind limbs, pelvis and tail.  相似文献   

8.
Reasons for performing study: Dexmedetomidine has been administered in the equine as a constant‐rate infusion (CRI) during inhalation anaesthesia, preserving optimal cardiopulmonary function with calm and coordinated recoveries. Inhalant anaesthetic sparing effects have been demonstrated in other species, but not in horses. Objectives: To determine the effects of a CRI of dexmedetomidine on the minimal alveolar concentration (MAC) of sevoflurane in ponies. Methods: Six healthy adult ponies were involved in this prospective, randomised, crossover, blinded, experimental study. Each pony was anaesthetised twice (3 weeks washout period). After induction with sevoflurane in oxygen (via nasotracheal tube), the ponies were positioned on a surgical table (T0), and anaesthesia was maintained with sevoflurane (expired sevoflurane fraction 2.5%) in 55% oxygen. The ponies were randomly allocated to treatment D (dexmedetomidine 3.5 µg/kg bwt i.v. [T10–T15] followed by a CRI of dexmedetomidine at 1.75 µg/kg bwt/h) or treatment S (bolus and CRI of saline at the same volume and rate as treatment D). After T60, MAC determination, using a classic bracketing technique, was initiated. Stimuli consisted of constant‐current electrical stimuli at the skin of the lateral pastern region. Triplicate MAC estimations were obtained and averaged in each pony. Monitoring included pulse oximetry, electrocardiography, anaesthetic gas monitoring, arterial blood pressure measurement and arterial blood gases. Normocapnia was maintained by mechanical ventilation. Analysis of variance (treatment and period as fixed factors) was used to detect differences between treatments (α= 0.05). Results: An intravenous (i.v.) dexmedetomidine CRI decreased mean ± s.d. sevoflurane MAC from 2.42 ± 0.55 to 1.07 ± 0.21% (mean MAC reduction 53 ± 15%). Conclusions and potential relevance: A dexmedetomidine CRI at the reported dose significantly reduces the MAC of sevoflurane.  相似文献   

9.
OBJECTIVE: To compare the effects of two balanced anaesthetic protocols on end-tidal isoflurane (Fe'ISO), cardiopulmonary performance and quality of recovery in horses. DESIGN: Prospective blinded randomized clinical study. ANIMALS: Sixty-nine client-owned horses, American Society of Anesthesiologists category I and II, undergoing elective surgery. METHODS: The horses were premedicated with acepromazine (0.03 mg kg(-1)) IM 30-60 minutes before induction of anaesthesia and were randomly assigned to one of two treatments: in group L (37 horses) xylazine (1 mg kg(-1)) and in group M (31 horses) medetomidine (7 microg kg(-1)) was administered IV for sedation. Anaesthesia was induced 5 minutes later with ketamine (2.2 mg kg(-1)) and diazepam (0.02 mg kg(-1)) IV and maintained with isoflurane in oxygen/air (initial FIO2 0.40-0.50) and a constant rate infusion (CRI) of either lidocaine (2 mg kg(-1)/15 minutes loading dose followed by 50 microg kg(-1) minute(-1)) (group L) or medetomidine (3.5 microg kg(-1) hour(-1)) (group M). If horses showed movement or nystagmus, additional thiopental or ketamine was administered. Heart rate, mean arterial pressure (MAP), Fe'ISO and arterial blood gases were measured. Cardiac output was measured with the lithium dilution method in 10 (group L) and 11 (group M) horses every 45 minutes. Recovery was scored. RESULTS: Heart rate and the cardiac index (CI) were significantly higher in group L with changes over time. In group M, MAP was significantly higher during the first 50 minutes. Group L needed more additional ketamine and thiopental to maintain a surgical plane of anaesthesia and Fe'ISO was significantly higher from 70 minutes. Recovery was longer in group M and of better quality. The significance level was set at p < 0.05. CONCLUSIONS AND CLINICAL RELEVANCE: In group M, maintenance of stable anaesthetic depth was easier and lower Fe'ISO was required to maintain a surgical plane of anaesthesia. Recoveries were longer but of better quality. The CI was higher in group L but cardiovascular function was generally well maintained in both groups.  相似文献   

10.
The objective of this study was to compare the effect on the minimum alveolar concentration (MAC) of isoflurane when ketamine was administered either after or without prior determination of the baseline MAC of isoflurane in rabbits. Using a prospective randomized crossover study, 8 adult, female New Zealand rabbits were allocated to 2 treatment groups. Anesthesia was induced and maintained with isoflurane. Group 1 (same-day determination) had the MAC-sparing effect of ketamine [1 mg/kg bodyweight (BW) bolus followed by a constant rate infusion (CRI) of 40 μg/kg BW per min, given by intravenous (IV)], which was determined after the baseline MAC of isoflurane was determined beforehand. A third MAC determination was started 30 min after stopping the CRI. Group 2 (separate-day determination) had the MAC-sparing effect of ketamine determined without previous determination of the baseline MAC of isoflurane. A second MAC determination was started 30 min after stopping the CRI. In group 1, the MAC of isoflurane (2.15 ± 0.09%) was significantly decreased by ketamine (1.63 ± 0.07%). After stopping the CRI, the MAC was significantly less (2.04 ± 0.11%) than the baseline MAC of isoflurane and significantly greater than the MAC during the CRI. In group 2, ketamine decreased isoflurane MAC (1.53 ± 0.22%) and the MAC increased significantly (1.94 ± 0.25%) after stopping the CRI. Minimum alveolar concentration (MAC) values did not differ significantly between the groups either during ketamine administration or after stopping ketamine. Under the study conditions, prior determination of the baseline isoflurane MAC did not alter the effect of ketamine on MAC. Both methods of determining MAC seemed to be valid for research purposes.  相似文献   

11.
REASONS FOR PERFORMING STUDY: Absorption of endotoxin across ischaemic-injured mucosa is a major cause of mortality after colic surgery. Recent studies have shown that flunixin meglumine retards mucosal repair. Systemic lidocaine has been used to treat post operative ileus, but it also has novel anti-inflammatory effects that could improve mucosal recovery after ischaemic injury. HYPOTHESIS: Systemic lidocaine ameliorates the deleterious negative effects of flunixin meglumine on recovery of mucosal barrier function. METHODS: Horses were treated i.v. immediately before anaesthesia with either 0.9% saline 1 ml/50 kg bwt, flunixin meglumine 1 mg/kg bwt every 12 h or lidocaine 1.3 mg/kg bwt loading dose followed by 0.05 mg/kg bwt/min constant rate infusion, or both flunixin meglumine and lidocaine, with 6 horses allocated randomly to each group. Two sections of jejunum were subjected to 2 h of ischaemia by temporary occlusion of the local blood supply, via a midline celiotomy. Horses were monitored with a behavioural pain score and were subjected to euthanasia 18 h after reversal of ischaemia. Ischaemic-injured and control jejunum was mounted in Ussing chambers for measurement of transepithelial electrical resistance (TER) and permeability to lipopolysaccharide (LPS). RESULTS: In ischaemic-injured jejunum TER was significantly higher in horses treated with saline, lidocaine or lidocaine and flunixin meglumine combined, compared to horses treated with flunixin meglumine. In ischaemic-injured jejunum LPS permeability was significantly increased in horses treated with flunixin meglumine alone. Behavioural pain scores did not increase significantly after surgery in horses treated with flunixin meglumine. CONCLUSIONS: Treatment with systemic lidocaine ameliorated the inhibitory effects of flunixin meglumine on recovery of the mucosal barrier from ischaemic injury, when the 2 treatments were combined. The mechanism of lidocaine in improving mucosal repair has not yet been elucidated.  相似文献   

12.
The dissociative anaesthetic ketamine is reported to provide potent analgesia after administration of subanaesthetic doses in human beings. To evaluate the analgesic effects of ketamine as an adjunct to inhalation anaesthesia in horses, haemodynamic and electroencephalographic changes were recorded for 10 min after injection of ketamine (0.5 mg/kg iv; n=7) or equal volumes of 0.9% NaCl solution (n=5) in surgically stimulated horses anaesthetised at approximately 1.3% end-tidal concentration of isoflurane. Neither the haemodynamic variables (mean arterial blood pressure and heart rate) nor the quantitated EEG variables (theta/delta ratio, alpha/delta ratio, beta/delta ratio, median power frequency) and 80% spectral edge frequency were affected significantly by the ketamine dose used. Comparing data obtained from both groups of horses, our results suggest that iv administration of 0.5 mg/kg bwt of ketamine was ineffective in suppressing haemodynamic and electroencephalographic responses to surgical stimulation.  相似文献   

13.
Reasons for performing study: Studies have demonstrated the clinical usefulness of propofol for anaesthesia in horses but the use of a concentrated solution requires further investigation. Objectives: To determine the anaesthetic and cardiorespiratory responses to a bolus injection of 10% propofol solution in mature horses. Methods: Three randomised crossover experimental trials were completed. Trial 1: 6 horses were selected randomly to receive 10% propofol (2, 4 or 8 mg/kg bwt i.v.). Trial 2: 6 horses received 1.1 mg/kg bwt i.v. xylazine before being assigned at random to receive one of 5 different doses (1–5 mg/kg bwt) of 10% propofol. Trial 3: 6 horses were sedated with xylazine (0.5 mg/kg bwt, i.v.) and assigned randomly to receive 10% propofol (3, 4 or 5 mg/kg bwt, i.v.); anaesthesia was maintained for 60 min using an infusion of 1% propofol (0.2‐0.4 mg/kg bwt/min). Cardiorespiratory data, the quality of anaesthesia, and times for induction, maintenance and recovery from anaesthesia and the number of attempts to stand were recorded. Results: Trial 1 was terminated after 2 horses had received each dose of 10% propofol. The quality of induction, anaesthesia and recovery from anaesthesia was judged to be unsatisfactory. Trial 2: 3 horses administered 1 mg/kg bwt and one administered 2 mg/kg bwt were not considered to be anaesthetised. Horses administered 3–5 mg/kg bwt i.v. propofol were anaesthetised for periods ranging from approximately 10–25 min. The PaO2 was significantly decreased in horses administered 3–5 mg/kg bwt i.v. propofol. Trial 3: The quality of induction and recovery from anaesthesia were judged to be acceptable in all horses. Heart rate and rhythm, and arterial blood pressure were unchanged or decreased slightly during propofol infusion period. Conclusions: Anaesthesia can be induced with a 10% propofol solution and maintained with a 1% propofol solution in horses administered xylazine as preanaesthetic medication. Hypoventilation and hypoxaemia may occur following administration to mature horses. Potential relevance: Adequate preanaesthetic sedation and oxygen supplementation are required in horses anaesthetised with propofol.  相似文献   

14.
REASONS FOR PERFORMING STUDY: In order to evaluate its potential as an adjunct to inhalant anaesthesia in horses, the pharmacokinetics of fentanyl must first be determined. OBJECTIVES: To describe the pharmacokinetics of fentanyl and its metabolite, N-[1-(2-phenethyl-4-piperidinyl)maloanilinic acid (PMA), after i.v. administration of a single dose to horses that were awake in Treatment 1 and anaesthetised with isoflurane in Treatment 2. METHODS: A balanced crossover design was used (n = 4/group). During Treatment 1, horses received a single dose of fentanyl (4 microg/kg bwt, i.v.) and during Treatment 2, they were anaesthetised with isoflurane and maintained at 1.2 x minimum alveolar anaesthetic concentration. After a 30 min equilibration period, a single dose of fentanyl (4 microg/kg bwt, i.v.) was administered to each horse. Plasma fentanyl and PMA concentrations were measured at various time points using liquid chromatography-mass spectrometry. RESULTS: Anaesthesia with isoflurane significantly decreased mean fentanyl clearance (P < 0.05). The fentanyl elimination half-life, in awake and anaesthetised horses, was 1 h and volume of distribution at steady state was 0.37 and 0.26 l/kg bwt, respectively. Anaesthesia with isoflurane also significantly decreased PMA apparent clearance and volume of distribution. The elimination half-life of PMA was 2 and 1.5 h in awake and anaesthetised horses, respectively. CONCLUSIONS AND POTENTIAL RELEVANCE: Pharmacokinetics of fentanyl and PMA in horses were substantially altered in horses anaesthetised with isoflurane. These pharmacokinetic parameters provide information necessary for determination of suitable fentanyl loading and infusion doses in awake and isoflurane-anaesthetised horses.  相似文献   

15.
The effects of fentanyl on the minimum alveolar concentration (MAC) of isoflurane and cardiovascular function in mechanically ventilated goats were evaluated using six healthy goats (three does and three wethers). Following induction of general anaesthesia with isoflurane delivered via a mask, endotracheal intubation was performed and anaesthesia was maintained with isoflurane. The baseline MAC of isoflurane (that is, the lowest alveolar concentration required to prevent gross purposeful movement) in response to clamping a claw with a vulsellum forceps was determined. Immediately after baseline isoflurane MAC determination, the goats received, on separate occasions, one of three fentanyl treatments, administered intravenously: a bolus of 0.005 mg/kg followed by constant rate infusion (CRI) of 0.005 mg/kg/hour (treatment LFENT), a bolus of 0.015 mg/kg followed by CRI of 0.015 mg/kg/hour (treatment MFENT) or a bolus of 0.03 mg/kg followed by CRI of 0.03 mg/kg/hour (treatment HFENT). Isoflurane MAC was redetermined during the fentanyl CRI treatments. Cardiopulmonary parameters were monitored. A four-week washout period was allowed between treatments. The observed baseline isoflurane MAC was 1.32 (1.29 to 1.36) per cent. Isoflurane MAC decreased to 0.98 (0.92 to 1.01) per cent, 0.75 (0.69 to 0.79) per cent and 0.58 (0.51 to 0.65) per cent following LFENT, MFENT and HFENT respectively. Cardiovascular function was not adversely affected. The quality of recovery from general anaesthesia was good, although exaggerated tail-wagging was observed in some goats following MFENT and HFENT.  相似文献   

16.
OBJECTIVE: To quantitate the dose and time-related effects of morphine sulfate on the anesthetic sparing effect of xylazine hydrochloride in halothane-anesthetized horses and determine the associated plasma xylazine and morphine concentration-time profiles. ANIMALS: 6 healthy adult horses. PROCEDURE: Horses were anesthetized 3 times to determine the minimum alveolar concentration (MAC) of halothane in O2 and characterize the anesthetic sparing effect (ie, decrease in MAC of halothane) by xylazine (0.5 mg/kg, i.v.) administration followed immediately by i.v. administration of saline (0.9% NaCI) solution, low-dose morphine (0.1 mg/kg), or high-dose morphine (0.2 mg/kg). Selected parameters of cardiopulmonary function were also determined over time to verify consistency of conditions. RESULTS: Mean (+/- SEM) MAC of halothane was 1.05 +/- 0.02% and was decreased by 20.1 +/- 6.6% at 49 +/- 2 minutes following xylazine administration. The amount of MAC reduction in response to xylazine was time dependent. Addition of morphine to xylazine administration did not contribute further to the xylazine-induced decrease in MAC (reductions of 21.9 +/- 1.2 and 20.7 +/- 1.5% at 43 +/- 4 and 40 +/- 4 minutes following xylazine-morphine treatments for low- and high-dose morphine, respectively). Overall, cardiovascular and respiratory values varied little among treatments. Kinetic parameters describing plasma concentration-time curves for xylazine were not altered by the concurrent administration of morphine. CONCLUSIONS AND CLINICAL RELEVANCE: Administration of xylazine decreases the anesthetic requirement for halothane in horses. Concurrent morphine administration to anesthetized horses does not alter the anesthetic sparing effect of xylazine or its plasma concentration-time profile.  相似文献   

17.
Reasons for performing study: No studies have been reported on the effects of enoximone in anaesthetised colic horses. Objective: To examine whether enoximone improves cardiovascular function and reduces dobutamine requirement in anaesthetised colic horses. Methods: Forty‐eight mature colic horses were enrolled in this prospective, randomised clinical trial. After sedation (xylazine 0.7 mg/kg bwt) and induction (midazolam 0.06 mg/kg bwt, ketamine 2.2 mg/kg bwt), anaesthesia was maintained with isoflurane in oxygen and a lidocaine constant rate infusion (1.5 mg/kg bwt, 2 mg/kg/h). Horses were ventilated (PaCO2<8.00 kPa). If hypotension occurred, dobutamine and/or colloids were administered. Ten minutes after skin incision, horses randomly received an i.v. bolus of enoximone (0.5 mg/kg bwt) or saline. Monitoring included respiratory and arterial blood gases, heart rate (HR), arterial pressure and cardiac index (CI). Systemic vascular resistance (SVR), stroke index (SI) and oxygen delivery index (DO2I) were calculated. For each variable, changes between baseline and T10 within each treatment group and/or colic type (small intestines, large intestines or mixed) were analysed and compared between treatments in a fixed effects model. Differences between treatments until T30 were investigated using a mixed model (α= 0.05). Results: Ten minutes after enoximone treatment, CI (P = 0.0010), HR (P = 0.0033) and DO2I (P = 0.0007) were higher and SVR lower (P = 0.0043) than at baseline. The changes in CI, HR and SVR were significantly different from those after saline treatment. During the first 30 min after enoximone treatment, DO2I (P = 0.0224) and HR (P = 0.0003) were higher than after saline administration. Because the difference in HR between treatments was much clearer in large intestine colic cases, an interaction was detected between treatment and colic type in both analyses (P = 0.0076 and 0.0038, respectively). Conclusions: Enoximone produced significant, but short lasting, cardiovascular effects in colic horses. Potential relevance: Enoximone's cardiovascular effects in colic horses were of shorter duration than in healthy ponies.  相似文献   

18.
This study aimed to evaluate the effects of a constant rate infusion (CRI) of xylazine or xylazine in combination with lidocaine on nociception, sedation, and physiologic values in horses. Six horses were given intravenous (IV) administration of a loading dose (LD) of 0.55 mg/kg of xylazine followed by a CRI of 1.1 mg/kg/hr. The horses were randomly assigned to receive three treatments, on different occasions, administered 10 minutes after initiation of the xylazine CRI, as follows: control, physiologic saline; lidocaine low CRI (LLCRI), lidocaine (LD: 1.3 mg/kg, CRI: 0.025 mg/kg/min); and lidocaine high CRI (LHCRI), lidocaine (LD: 1.3 mg/kg, CRI: 0.05 mg/kg/min). A blinded observer assessed objective and subjective data for 50 minutes during the CRIs. In all treatments, heart and respiratory rates decreased, end-tidal carbon dioxide concentration increased, and moderate to intense sedation was observed, but no significant treatment effect was detected in these variables. Ataxia was significantly higher in LHCRI than in the control treatment at 20 minutes of infusion. Compared with baseline values, nociceptive threshold increased to as much as 79% in the control, 190% in LLCRI, and 158% in LHCRI. Nociceptive threshold was significantly higher in LLCRI (at 10 and 50 minutes) and in LHCRI (at 30 minutes) than in the control treatment. The combination of CRIs of lidocaine with xylazine produced greater increases in nociceptive threshold compared with xylazine alone. The effects of xylazine on sedation and cardiorespiratory variables were not enhanced by the coadministration of lidocaine. The potential to increase ataxia may contraindicate the clinical use of LHCRI, in combination with xylazine, in standing horses.  相似文献   

19.
Objective To evaluate the effects of a constant rate infusion (CRI) of romifidine on the requirement of isoflurane, cardiovascular performance and recovery in anaesthetized horses undergoing arthroscopic surgery. Study design Randomized blinded prospective clinical trial. Animals Thirty horses scheduled for routine arthroscopy. Methods After premedication (acepromazine 0.02 mg kg?1, romifidine 80 μg kg?1, methadone 0.1 mg kg?1) and induction (midazolam 0.06 mg kg?1 ketamine 2.2 mg kg?1), anaesthesia was maintained with isoflurane in oxygen. Horses were assigned randomly to receive a CRI of saline (group S) or 40 μg kg?1 hour?1 romifidine (group R). The influences of time and treatment on anaesthetic and cardiovascular parameters were evaluated using an analysis of variance. Body weight (t‐test), duration of anaesthesia (t‐test) and recovery score (Wilcoxon Rank Sum Test) were compared between groups. Significance was set at p < 0.05. Results All but one horse were positioned in the dorsal recumbent position and ventilated from the start of anaesthesia. End tidal isoflurane concentrations were similar in both groups at similar time points and over the whole anaesthetic period. Cardiac output was significantly lower in horses of the R group, but there were no significant differences between groups in cardiac index, body weight or age. All other cardiovascular parameters were similar in both groups. Quality of recovery did not differ significantly between groups, but more horses in group R stood without ataxia at the first attempt. One horse from group S had a problematic recovery. Conclusions and clinical relevance No inhalation anaesthetic sparing effect or side effects were observed by using a 40 μg kg?1 hour?1 romifidine CRI in isoflurane anaesthetized horses under clinical conditions. Cardiovascular performance remained acceptable. Further studies are needed to identify the effective dose of romifidine that will induce an inhalation anaesthetic sparing effect in anaesthetized horses.  相似文献   

20.
OBJECTIVE: To evaluate the effects of i.v. lidocaine (L) and ketamine (K), alone and in combination (LK), on the minimum alveolar concentration (MAC) of isoflurane (ISO) in goats. STUDY DESIGN: Randomized crossover design. ANIMALS: Eight, adult mixed breed castrated male goats, aged 1-2 years weighing 24-51 kg. METHODS: Anesthesia was induced with ISO that was delivered via a mask. The tracheas were intubated and the animals ventilated to maintain an end-tidal carbon dioxide partial pressure between 25 and 30 mmHg (3.3-4 kPa). Baseline MAC (MAC(B)) that prevented purposeful movement in response to clamping a claw was determined in triplicate. After MAC(B) determination, each goat received one of the following treatments, which were administered as a loading (LD) dose followed by a constant rate infusion, IV: L (2.5 mg kg(-1); 100 microg kg(-1) minute(-1)), K (1.5 mg kg(-1); 50 microg kg(-1) minute(-1)), L and K combination or saline, and the MAC (MAC(T)) was re-determined in triplicate. Plasma concentrations of L and K were measured around each MAC point and the values averaged. RESULTS: The least-squares mean MAC(B) for all treatments was 1.13 +/- 0.03%. L, K, and LK reduced (p < 0.05) MAC(B) by 18.3%, 49.6% and 69.4%, respectively. Plasma concentrations for L, K, and LK were 1617 +/- 385, 1535 +/- 251 and 1865 +/- 317/1467 +/- 185 ng mL(-1), respectively. No change (p > 0.05) occurred with saline. CONCLUSION: Lidocaine and K caused significant decreases in the MAC of ISO. The combination (LK) had an additive effect. However, the plasma L concentrations were less than predicted, as was the MAC reduction with L. CLINICAL RELEVANCE: The use of L, K and the combination, at the doses studied, will allow a clinically important reduction in the concentration of ISO required to maintain general anesthesia in goats.  相似文献   

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