Clinical evaluation of propofol as an intravenous anaesthetic agent in cats and dogs

The clinical efficacy and safety of an emulsion containing 10 mg/ml of the intravenous anaesthetic propofol were evaluated in cats and dogs by veterinary surgeons in eight practices in the United Kingdom. A total of 290 dogs and 207 cats were anaesthetised with propofol either as a single injection for procedures of short duration, or as an induction agent with maintenance provided by further incremental injections or as an induction agent with maintenance by gaseous agents. The mean induction doses of propofol for unpremedicated dogs and cats were respectively 6.55 mg/kg and 8.03 mg/kg. The mean induction doses after premedication with a tranquilliser were 4.5 mg/kg and 5.97 mg/kg for dogs and cats, respectively. Mean recovery times ranged, depending on the method of anaesthesia, from 23 to 40 minutes in dogs and from 27 to 38 minutes in cats; recovery was defined as the time at which the animals were alert and able to stand. Adverse side effects were infrequent, apnoea during induction being the commonest. Acepromazine and atropine were most often used as premedicants although in a few cases diazepam, xylazine and other agents were employed. No clinical incompatibility was observed between propofol and any of the other agents administered during the study. The rapid and usually excitement-free recovery of the animals was a valuable feature of anaesthesia with propofol.     

Assessment of methadone as an anaesthetic premedicant in cats

Ninety cats scheduled to undergo surgical procedures requiring the provision of postoperative analgesia were premedicated with either 0·1, 0·3 or 0·5 mgl/kg of racemic methadone by intramuscular injection. Each cat was assessed on three behavioural criteria before administration and again 20 minutes later. In a further 20 cats a specific assessment was made of the respiratory rate, heart rate and intraoperative minute volume during ovariohysterectomy following premedication with methadone (0·5 mgl/kg intramuscularly). In these cats an assessment of duration of analgesia was attempted. There was no significant change in behavioural scores following premedication with methadone. No cat vomited or became excited. No evidence of serious respiratory depression was found in the 20 cats monitored in detail. Duration of analgesia in cats receiving methadone (0·5 mgl/kg intramuscularly) before ovariohysterectomy varied from 1·5 to over 6·5 hours. Methadone may be used at dose rates of up to 0·5 mg/kg as a premedicant for cats without significant risk of undesirable behavioural changes or serious intraoperative respiratory depression when combined with the anaesthetic protocol described.     

Propofol as an intravenous anaesthetic agent in dogs

Studies in dogs with an emulsion formulation of the intravenous anaesthetic, propofol, showed that induction of anaesthesia was smooth and it was possible to maintain anaesthesia by intermittent injection. The mean dose for induction of anaesthesia in unpremedicated dogs was 5.95 mg/kg body-weight. When no premedication was administered anaesthesia was maintained by a total dose of approximately 0.806 mg/kg/minute. Premedication with between 0.02 and 0.04 mg/kg of acepromazine reduced the mean induction dose by about 30 per cent and the maintenance dose by more than 50 per cent. In 68 unpremedicated dogs given one dose, recovery was complete in a mean time of 18 minutes and after maintenance of anaesthesia by intermittent injection in 65 dogs the mean recovery time was 22 minutes from administration of the last dose. Premedication with acepromazine did not produce statistically significant increases in these recovery times. The quiet, rapid and complete recovery proved to be most valuable in cases where the animal had to be returned to the owners' care with the minimum of delay.     

An evaluation of anaesthetic induction in healthy dogs using rapid intravenous injection of propofol or alfaxalone

ObjectiveTo evaluate quality of anaesthetic induction and cardiorespiratory effects following rapid intravenous (IV) injection of propofol or alfaxalone.Study designProspective, randomised, blinded clinical study.AnimalsSixty healthy dogs (ASA I/II) anaesthetized for elective surgery or diagnostic procedures.MethodsPremedication was intramuscular acepromazine (0.03 mg kg^?1) and meperidine (pethidine) (3 mg kg^?1). For anaesthetic induction dogs received either 3 mg kg^?1 propofol (Group P) or 1.5 mg kg^?1 alfaxalone (Group A) by rapid IV injection. Heart rate (HR), respiratory rate (f_R) and oscillometric arterial pressures were recorded prior to induction, at endotracheal intubation and at 3 and 5 minutes post-intubation. The occurrence of post-induction apnoea or hypotension was recorded. Pre-induction sedation and aspects of induction quality were scored using 4 point scales. Data were analysed using Chi-squared tests, two sample t-tests and general linear model mixed effect anova (p < 0.05).ResultsThere were no significant differences between groups with respect to sex, age, body weight, f_R, post-induction apnoea, arterial pressures, hypotension, SpO₂, sedation score or quality of induction scores. Groups behaved differently over time with respect to HR. On induction HR decreased in Group P (?2 ± 28 beats minute^?1) but increased in Group A (14 ± 33 beats minute^?1) the difference being significant (p = 0.047). However HR change following premedication also differed between groups (p = 0.006). Arterial pressures decreased significantly over time in both groups and transient hypotension occurred in eight dogs (five in Group P, three in Group A). Post-induction apnoea occurred in 31 dogs (17 in Group P, 14 in Group A). Additional drug was required to achieve endotracheal intubation in two dogs.Conclusions and Clinical relevanceRapid IV injection of propofol or alfaxalone provided suitable conditions for endotracheal intubation in healthy dogs but post-induction apnoea was observed commonly.     

Clinical evaluation in cats of a new anaesthetic, GT 1341

The results of a co-ordinated multicentred clinical evaluation of a new steroid anaesthetic for cats, CT 1341, are presented. Forty-six practising veterinary surgeons were involved. Administration by the intravenous, intramuscular and combined intramuscular-intravenous routes was tried. It was concluded that CT 1341 is a safe anaesthetic in cat practice when given intravenously. When employed by the intramuscular route it induced deep sedation and in some cases anaesthesia, depending on the dosage used.     

Cardiorespiratory and anaesthetic effects of two continuous rate infusions of dexmedetomidine in alfaxalone anaesthetized dogs

Six Beagles were used in this prospective randomised crossover experimental study. Dexmedetomidine was administered at 0, 1 or 2 μg/kg IV for group C, LDA and HDA, respectively. Animals were induced and maintained with alfaxalone at 0.07 mg/kg/min with a CRI dexmedetomidine dose of 0, 0.5 or 1 μg/kg/h for group C, LDA and HDA, respectively. Cardiorespiratory variables, arterial blood gases and depth of anaesthesia were recorded. The recovery times and quality of recovery were scored. Group HDA produced a greater increase in the depth of anaesthesia than LDA. However, with both protocols, CI was halved compared to normal values in dogs. The use of oxygen before and during the anaesthetic maintenance is advisable, mainly if dexmedetomidine is going to be use as a pre-medicant and maintenance agent. The quality of recovery was better in groups receiving dexmedetomidine, without causing an increase in recovery time.     

Clinical evaluation of the anaesthetic sparing effect of brachial plexus block in cats

ObjectiveTo evaluate the isoflurane sparing effect and the post-surgical analgesia provided by a brachial plexus block (BPB) in cats undergoing distal thoracic limb surgery.Study designProspective randomized blinded clinical study.AnimalsTwenty client-owned cats.MethodsCats were assigned to receive either no BPB (group NB) or a nerve stimulator guided BPB (group BPB) using lidocaine (3.6 mg kg^?1) and bupivacaine (1.2 mg kg^?1). Pre-medication consisted of midazolam and ketamine intravenously (IV). Anaesthesia was induced with propofol IV to effect and maintained with isoflurane delivered in oxygen and a continuous rate infusion of fentanyl (2 μg kg^?1 hour^?1). End-tidal isoflurane concentration (Fe′ISO) was adjusted every 3 minutes guided by changes in cardiorespiratory parameters and reflexes present, to maintain a stable depth of anaesthesia. Five time points were chosen to record all parameters and compare values between groups. Recovery and post-operative pain assessment were performed using a visual analogue scale (VAS) at 15 and 45 minutes after extubation and thereafter at hourly intervals until 5 hours after placement of the BPB.ResultsNo clinically significant differences were seen for heart rate, respiratory rate and non-invasive blood pressure between groups. Mean Fe′ISO was significantly lower in group BPB compared with group NB at all time points. In group NB, all intraoperative measurements of Fe′ISO were significantly higher compared with baseline (3 minutes before start of surgery) measurements. During recovery, VAS scores for group BPB were significantly lower than for group NB. Additional analgesics were needed in all cats within the study period.Conclusion and Clinical relevanceIn cats undergoing orthopaedic surgery of the thoracic limb, BPB reduced intra-operative isoflurane requirement and pain during the early post-operative period when compared with procedures without a BPB. BPB is a useful adjunct to anaesthesia in such cases.     

A clinical comparison of two anaesthetic protocols using lidocaine or medetomidine in horses

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.     

Neuraxial morphine induced pruritus in two cats and treatment with sub anaesthetic doses of propofol

HistoryTwo cats were presented for orthopaedic surgery.Physical ExaminationWith the exception of the orthopaedic injuries found, clinical examination showed no abnormality.ManagementAs part of anaesthetic management, one cat received intrathecal morphine, the other epidural morphine. Following recovery, intense grooming was observed. After ensuring adequate analgesia this behaviour was interpreted as pruritus.In the first cat, pruritus was initially managed with medetomidine constant rate infusion (CRI) at 1 and 1.5 μg kg^?1 hour^?1. The lower dose produced sedation and no relief from pruritus, the higher dose ablated pruritus but induced sedation. Two propofol (lipid emulsion formulation) boli of 0.1 mg kg^?1 ablated pruritus without causing sedation. The second cat was successfully treated with four boli of 0.1 mg kg^?1 propofol over 20 minutes.Follow–upFollowing treatment with propofol, pruritus did not recur in either cat and both were discharged from the hospital.ConclusionsThis is the first clinical report of morphine–induced pruritus in cats and management with low–dose propofol. These cases suggest an antipruritic mechanism for lipid–formulation propofol.     

Clinical evaluation of ketamine and lidocaine intravenous infusions to reduce isoflurane requirements in horses under general anaesthesia

ObjectiveTo compare isoflurane alone or in combination with systemic ketamine and lidocaine for general anaesthesia in horses.Study designProspective, randomized, blinded clinical trial.AnimalsForty horses (ASA I-III) undergoing elective surgery.MethodsHorses were assigned to receive isoflurane anaesthesia alone (ISO) or with ketamine and lidocaine (LKI). After receiving romifidine, diazepam, and ketamine, the isoflurane end-tidal concentration was set at 1.3% and subsequently adjusted by the anaesthetist (unaware of treatments) to maintain a light plane of surgical anaesthesia. Animals in the LKI group received lidocaine (1.5 mg kg⁻¹ over 10 minutes, followed by 40 μg kg⁻¹ minute⁻¹) and ketamine (60 μg kg⁻¹ minute⁻¹), both reduced to 65% of the initial dose after 50 minutes, and stopped 15 minutes before the end of anaesthesia. Standard clinical cardiovascular and respiratory parameters were monitored. Recovery quality was scored from one (very good) to five (very poor). Differences between ISO and LKI groups were analysed with a two-sample t-test for parametric data or a Fischer's exact test for proportions (p < 0.05 for significance). Results are mean ± SD.ResultsHeart rate was lower (p = 0.001) for LKI (29 ± 4) than for ISO (34 ± 6). End-tidal concentrations of isoflurane (ISO: 1.57% ± 0.22; LKI: 0.97% ± 0.33), the number of horses requiring thiopental (ISO: 10; LKI: 2) or dobutamine (ISO:8; LKI:3), and dobutamine infusion rates (ISO:0.26 ± 0.09; LKI:0.18 ± 0.06 μg kg⁻¹ minute⁻¹) were significantly lower in LKI compared to the ISO group (p < 0.001). No other significant differences were found, including recovery scores.Conclusions and clinical relevanceThese results support the use of lidocaine and ketamine to improve anaesthetic and cardiovascular stability during isoflurane anaesthesia lasting up to 2 hours in mechanically ventilated horses, with comparable quality of recovery.     

Broken nasotracheal tube aspiration in a horse during anaesthetic recovery

A horse was presented for soft palate thermocautery and surgical advancement of the larynx under general anaesthesia, following a history of respiratory noise and poor athletic performance. Physical examination prior to surgery was unremarkable. The horse was anaesthetised and a 20 mm cuffed endotracheal tube (ETT) used to intubate the trachea via the right nostril. The cuff was deflated at the end of the procedure and the tube secured in place around the head of the horse for the recovery. The horse was assisted to standing and during this process the end of the nasotracheal tube broke and was observed hanging from the head collar. The remainder of the tube was aspirated into the trachea of the horse. The remaining length of endotracheal tube was removed using a modified endoscopic technique. The horse recovered with no further problems. An unusual complication of a nasotracheal tube left in situ for recovery in a horse is reported and possible reasons for this complication are discussed.     

Pharmacokinetics and effects of alfaxalone after intravenous and intramuscular administration to cats

AIMS: To determine the pharmacokinetics, and anaesthetic and sedative effects of alfaxalone after I/V and I/M administration to cats.

METHODS: Six European shorthair cats, three males and three females, with a mean weight of 4.21 (SD 0.53) kg and aged 3.8 (SD 0.9) years were enrolled in this crossover, two–treatment, two-period study. Alfaxalone at a dose of 5?mg/kg was administered either I/V or I/M. Blood samples were collected between 2–480 minutes after drug administration and analysed for concentrations of alfaxalone by HPLC. The plasma concentration-time curves were analysed by non-compartmental analysis. Sedation scores were evaluated between 5–120 minutes after drug administration using a numerical rating scale (from 0–18). Intervals from drug administration to sit, sternal and lateral recumbency during the induction phase, and to head-lift, sternal recumbency and standing position during recovery were recorded.

RESULTS: The mean half-life and mean residence time of alfaxalone were longer after I/M (1.28 (SD 0.21) and 2.09 (SD 0.36) hours, respectively) than after I/V (0.49 (SD 0.07) and 0.66 (SD 0.16) hours, respectively) administration (p<0.05). Bioavailability after I/M injection of alfaxalone was 94.7 (SD 19.8)%. The mean intervals to sternal and lateral recumbency were longer in the I/M (3.73 (SD 1.99) and 6.12 (SD 0.90) minutes, respectively) compared to I/V (0 minutes for all animals) treated cats (p<0.01). Sedation scores indicative of general anaesthesia (scores >15) were recorded from 5–15 minutes after I/V administration and deep sedation (scores 11–15) at 20 and 30 minutes. Deep sedation was observed from 10–45 minutes after I/M administration. One cat from each group showed hyperkinesia during recovery, and the remainder had an uneventful recovery.

CONCLUSIONS AND CLINICAL RELEVANCE: Alfaxalone administered I/V in cats provides rapid and smooth induction of anaesthesia. After I/M administration, a longer exposure to the drug and an extended half life were obtained compared to I/V administration. Therefore I/M administration of alfaxalone could be a reliable, suitable and easy route in cats, taking into account that alfaxalone has a slower onset of sedation than when given I/V and achieves deep sedation rather than general anaesthesia.     

Pharmacokinetic and pharmacodynamic evaluation of intravenous hydromorphone in cats

This study describes the pharmacokinetics of intravenous hydromorphone in cats and the simultaneous measurement of antinociceptive pharmacodynamic effects using a thermal threshold testing system. Following establishment of a baseline thermal threshold, six adult cats were administered 0.1 mg/kg of hydromorphone intravenously. Thermal threshold testing and blood collection were conducted simultaneously at predetermined time points. Plasma hydromorphone concentrations were determined by a liquid chromatographic-mass spectral method and pharmacokinetic analysis was performed by nonlinear least squares regression analysis. Plasma hydromorphone concentrations declined rapidly over time, and were below the limit of quantification of the assay (LOQ = 1.0 ng/mL) by 360 min. In contrast, thermal thresholds rose from a pretreatment value of 40.9 +/- 0.65 degrees C (mean +/- SEM) to instrument cut-out (55 degrees C) within 15 min and remained significantly elevated from 15-450 min after treatment. Inspection of the data revealed no direct correlation between plasma hydromorphone concentrations and the antinociceptive effect of this drug in cats. These findings support the importance of conducting pharmacokinetic studies in parallel with objective measurements of drug effect.     

Evaluation of an anaesthetic technique used in dogs undergoing craniectomy for tumour resection

ObjeCTIVE: To evaluate a total intravenous anaesthetic technique in dogs undergoing craniectomy. STUDY DESIGN: Prospective clinical study. ANIMALS: Ten dogs admitted for elective surgical resection of rostro-tentorial tumours. METHODS: All dogs were premedicated with methadone, 0.2 mg kg(-1) intramuscularly 30 minutes prior to induction of anaesthesia. Anaesthesia was induced with propofol administered intravenously (IV) to effect, following administration of lidocaine 1 mg kg(-1) IV and maintained with a continuous infusion of propofol at < or =0.4 mg kg(-1) minute(-1) during instrumentation and preparation and during movement of the animals to recovery. During surgery, anaesthesia was maintained using a continuous infusion of propofol at 相似文献   

Combination of zolazepam and tiletamine as a sedative and anaesthetic for wombats

Objective To assess the suitability of the combination of zolazepam and tiletamine for routine use as chemical restraint, sedative and anaesthetic in wild wombats.
Animals Sixty common wombats, 25 southern hairy-nosed wombats and 40 northern hairy-nosed wombats.
Procedure Wombats caught in cage-traps in the wild were given injections of the anaesthetic combination either intramuscularly or intraperitoneally. Anaesthesia was maintained for up to 4 h in some cases, and for 12 h in one case. All wombats were released after anaesthesia.
Results and conclusion
This drug combination is effective and apparently safe for the sedation or light anaesthesia of wombats. We did not observe adverse reactions or deaths and the dose range used (4 to 15 mg/kg) demonstrates a wide safety margin. The use of this anaesthetic combination was effective in reducing the stress to wombats from capture and handling.     

A comparison of subarachnoid buprenorphine or xylazine as an adjunct to lidocaine for analgesia in goats

ObjectiveTo test the hypothesis that subarachnoid administration of buprenorphine and lidocaine provides more intense and longer lasting perioperative analgesia with less side effects than xylazine and lidocaine in goats.Study designRandomized, blinded, controlled study.Study animals Ten healthy female goats randomly assigned to two groups of five animals each.MethodsAfter sedation with acepromazine (0.1 mg kg^?1) intravenously (IV), lidocaine 2% (0.1 mL kg^?1) combined with either xylazine (0.05 mg kg^?1; Group X) or buprenorphine (0.005 mg kg^?1; Group B) were injected intrathecally at the lumbo-sacral junction prior to stifle surgery. Electrocardiogram, heart rate, direct systolic, mean, and diastolic arterial blood pressures, rectal temperature and arterial blood gases were recorded as were post-operative sedation and pain scores using a visual analogue and numeric rating scale, respectively. Data were analyzed with one-way anova for repeated measures, one-way anova, Friedman's and Kruskal–Wallis tests as necessary (p< 0.05).ResultsSurgery was successfully performed under both analgesia protocols. Total pain and sedation scores were significantly lower in the B as compared with X group from 3–24 hours and 30–120 minutes, respectively after subarachnoid drug administration (SDA). Heart rate and arterial blood pressures decreased post SDA and were consistently lower in X versus B (p< 0.05). In B arterial blood gas parameters did not change post SDA, but in group X PaCO₂ increased slightly within 15 minutes of SDA and remained elevated for at least 3 hours (p< 0.05).ConclusionIn these goats intrathecal administration of buprenorphine and lidocaine produced more profound and longer lasting analgesia with less sedation and hemodynamic and respiratory impairment than xylazine with lidocaine.Clinical relevanceIn these goats undergoing hind limb surgery, subarachnoid buprenorphine/lidocaine offered more intense and longer lasting analgesia than a xylazine/lidocaine combination, with less sedation and impairment of cardiopulmonary function.