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1.

Objective

To evaluate the dose-sparing effect of midazolam or diazepam on the dose of alfaxalone required to achieve endotracheal intubation in premedicated dogs.

Study design

Prospective, randomized, ‘blinded’, controlled clinical trial.

Animals

Ninety healthy dogs anaesthetized for elective surgery or diagnostic procedures.

Methods

Saline (0.1 mL kg–1), or midazolam or diazepam (0.2, 0.3, 0.4 or 0.5 mg kg–1) intravenously (IV) was randomly assigned; investigators were unaware of group designation. After premedication with IV acepromazine 0.01 mg kg–1 and methadone 0.2 mg kg–1, the degree of sedation was assessed. Alfaxalone (0.5 mg kg–1) was administered IV, followed by the assigned treatment. Further alfaxalone was administered until endotracheal intubation could be performed. Ease of endotracheal intubation, pulse rate and arterial blood pressure were assessed. General linear models were used to examine the effect of treatment drug and dose on induction dose of alfaxalone with Tukey’s post hoc tests. Incidence of adverse reactions was assessed with chi-square tests.

Results

There were no significant differences between groups with regard to demographic data or sedation. Median (range) induction dose of alfaxalone in the saline group was 0.74 (0.43–1.26) mg kg–1 compared with 0.5 (0.46–0.75) mg kg–1 and 0.5 (0.42–1.2) mg kg–1 for the midazolam and diazepam groups, respectively. Midazolam 0.3 and 0.5 mg kg–1 (p = 0.005 and 0.044, respectively) and diazepam 0.4 mg kg–1 (p = 0.032) reduced the alfaxalone dose compared with saline. Adverse effects were not significantly different between groups. Midazolam 0.2, 0.3, 0.4 and 0.5 mg kg–1 (p < 0.044, p = 0.001, p = 0.007, p = 0.044, respectively) and diazepam 0.2 and 0.5 mg kg–1 (p = 0.025 and p = 0.025) improved intubation score compared with saline.

Conclusion and clinical relevance

Midazolam 0.3 and 0.5 mg kg–1 and diazepam 0.4 mg kg–1 coadministered at anaesthetic induction allow alfaxalone dose reduction in healthy dogs. Use of benzodiazepines improved the ease of endotracheal intubation.  相似文献   

2.

Objectives

To compare propofol and alfaxalone, with or without midazolam, for induction of anesthesia in fentanyl-sedated dogs, and to assess recovery from total intravenous anesthesia (TIVA).

Study design

Prospective, incomplete, Latin-square study.

Animals

Ten dogs weighing 24.5 ± 3.1 kg (mean ± standard deviation).

Methods

Dogs were randomly assigned to four treatments: treatment P-M, propofol (1 mg kg?1) and midazolam (0.3 mg kg?1); treatment P-S, propofol and saline; treatment A-M, alfaxalone (0.5 mg kg?1) and midazolam; treatment A-S, alfaxalone and saline, administered intravenously (IV) 10 minutes after fentanyl (7 μg kg?1) IV. Additional propofol or alfaxalone were administered as necessary for endotracheal intubation. TIVA was maintained for 35–55 minutes by infusions of propofol or alfaxalone. Scores were assigned for quality of sedation, induction, extubation and recovery. The drug doses required for intubation and TIVA, times from sedation to end of TIVA, end anesthesia to extubation and to standing were recorded. Analysis included a general linear mixed model with post hoc analysis (p < 0.05).

Results

Significant differences were detected in the quality of induction, better in A-M than A-S and P-S, and in P-M than P-S; in total intubation dose, lower in P-M (1.5 mg kg?1) than P-S (2.1 mg kg?1), and A-M (0.62 mg kg?1) than A-S (0.98 mg kg?1); and lower TIVA rate in P-M (268 μg kg?1 minute?1) than P-S (310 μg kg?1 minute?1). TIVA rate was similar in A-M and A-S (83 and 87 μg kg?1 minute?1, respectively). Time to standing was longer after alfaxalone than propofol, but was not influenced by midazolam.

Conclusions and clinical relevance

Addition of midazolam reduced the induction doses of propofol and alfaxalone and improved the quality of induction in fentanyl-sedated dogs. The dose rate of propofol for TIVA was decreased.  相似文献   

3.

Objective

To determine the suitability of alfaxalone total intravenous (IV) anaesthesia in horses and concurrently evaluate infusion rates, cardiovascular effects, pharmacokinetics and the quality of the anaesthetic recovery period.

Study design

Prospective, experimental study.

Animals

Eight Standardbred horses.

Methods

Horses were premedicated with IV acepromazine (0.03 mg kg–1) and xylazine (1 mg kg–1) and anaesthesia was induced with guaifenesin (35 mg kg–1) and alfaxalone (1 mg kg–1). Anaesthesia was maintained for 180 minutes using an IV infusion of alfaxalone at a rate determined by a horse’s response to a supramaximal electrical noxious stimulus. Venous blood samples were regularly collected to determine alfaxalone plasma concentrations and for pharmacokinetic analysis. Cardiopulmonary variables were monitored and the quality of the anaesthetic recovery period scored.

Results

The median (range) alfaxalone infusion rate was 3.1 (2.4–4.3) mg kg–1 hour–1. The mean ± standard deviation plasma elimination half-life, plasma clearance and volume of distribution for alfaxalone were 41 minutes, 25 ± 6.3 mL minute–1 kg–1 and 1.6 ± 0.5 L kg–1, respectively. During anaesthesia, mean arterial blood pressure was maintained above 70 mmHg in all horses. Cardiac index reached a minimum value (68% of baseline values) immediately after induction of anaesthesia and was maintained between 74% and 90% of baseline values for the remainder of the anaesthetic protocol. Following the cessation of the alfaxalone infusion, six of eight horses exhibited muscle tremors and paddling. All horses stood without incident on the first or second attempt with a median recovery score of 4.5 (good to excellent).

Conclusions and clinical relevance

Anaesthesia in horses can be maintained with an infusion of alfaxalone at approximately 3 mg kg–1 hour–1. The alfaxalone infusion rates used resulted in minimal haemodynamic changes and good recovery quality. Mean alfaxalone plasma concentration was stable over the infusion period and clearance rates were similar to previously published single-dose alfaxalone studies in horses.  相似文献   

4.

Objective

To study the effect of alternating the order of midazolam and alfaxalone administration on the incidence of behavioural changes, alfaxalone induction dose and some cardiorespiratory variables in healthy dogs.

Study design

Prospective, randomized, controlled, clinical trial.

Animals

A total of 33 client-owned dogs undergoing elective procedures.

Methods

Following intramuscular acepromazine (0.02 mg kg?1) and morphine (0.4 mg kg?1) premedication, anaesthesia was induced intravenously (IV) with a co-induction of either midazolam (0.25 mg kg?1) prior to alfaxalone (0.5 mg kg?1; group MA), or alfaxalone followed by midazolam at identical doses (group AM). The control group (CA) was administered normal saline IV prior to alfaxalone administration. Additional alfaxalone (0.25 mg kg?1 increments) was administered as required in all groups until orotracheal intubation was possible. Changes in behaviour, quality of induction, ease of intubation and incidence of adverse events at induction were recorded. Heart rate (HR), respiratory rate (fR) and systolic arterial blood pressure (SAP) were measured before treatments (baseline values), 30 minutes after premedication and at 0, 2, 5 and 10 minutes postintubation.

Results

The incidence of excitement was higher in group MA compared with groups CA (p = 0.005) and AM (p = 0.013). The mean induction dose of alfaxalone was lower in group AM compared with group CA (p = 0.003). Quality of induction and ease of intubation were similar among groups. Mean HR values decreased after premedication and increased after alfaxalone administration in all groups. Mean SAP values were similar between groups. The number of animals that required manual ventilation was higher in the MA group.

Conclusions and clinical relevance

Despite a lower occurrence of adverse events at induction in group AM compared with group MA and a reduction of alfaxalone dose requirement in group AM compared with group CA, the use of an alfaxalone–midazolam co-induction does not seem to produce any cardiovascular or respiratory benefits in healthy dogs.  相似文献   

5.

Objective

To determine the effect of fentanyl on the induction dose and minimum infusion rate of alfaxalone required to prevent movement in response to a noxious stimulus (MIRNM) in dogs.

Study design

Experimental crossover design.

Animals

A group of six healthy, adult, intact female mixed-breed dogs, weighing 19.7 ± 1.3 kg.

Methods

Dogs were randomly administered one of three treatments at weekly intervals: premedication with 0.9% saline (treatment A), fentanyl 5 μg kg–1 (treatment ALF) or fentanyl 10 μg kg–1 (treatment AHF), administered intravenously over 5 minutes. Anesthesia was induced 5 minutes later with incremental doses of alfaxalone to achieve intubation and was maintained for 90 minutes in A with alfaxalone (0.12 mg kg–1 minute–1), in ALF with alfaxalone (0.09 mg kg–1 minute–1) and fentanyl (0.1 μg kg–1 minute–1) and in AHF with alfaxalone (0.06 mg kg–1 minute–1) and fentanyl (0.2 μg kg–1 minute–1). The alfaxalone infusion was increased or decreased by 0.006 mg kg–1 minute–1 based on positive or negative response to antebrachium stimulation (50 V, 50 Hz, 10 ms). Data were analyzed using a mixed-model anova and presented as least squares means ± standard error.

Results

Alfaxalone induction doses were 3.50 ± 0.13 (A), 2.17 ± 0.10 (ALF) and 1.67 ± 0.10 mg kg–1 (AHF) and differed among treatments (p < 0.05). Alfaxalone MIRNM was 0.17 ± 0.01 (A), 0.10 ± 0.01 (ALF) and 0.07 ± 0.01 mg kg–1 minute–1 (AHF) and differed among treatments. ALF and AHF decreased the MIRNM by 44 ± 8% and 62 ± 5%, respectively (p < 0.05). Plasma alfaxalone concentrations at MIRNM were 5.82 ± 0.48 (A), 4.40 ± 0.34 (ALF) and 2.28 ± 0.09 μg mL–1 (AHF).

Conclusions and clinical relevance

Fentanyl, at the doses studied, significantly decreased the alfaxalone induction dose and MIRNM.  相似文献   

6.

Objective

The evaluation of alfaxalone as a premedication agent and intravenous anaesthetic in pigs.

Study design

Prospective, clinical trial.

Animals

Nine healthy, 6–8-week-old female Landrace pigs weighing 22.2 ± 1.0 kg, undergoing epidural catheter placement.

Methods

All pigs were premedicated with 4 mg kg?1 alfaxalone, 40 μg kg?1 medetomidine and 0.4 mg kg?1 butorphanol administered in the cervical musculature. Sedation was subjectively scored by the same observer from 1 (no sedation) to 10 (profound sedation) prior to induction of anaesthesia with alfaxalone intravenously to effect. All pigs were maintained on alfaxalone infusions with the rate of administration adjusted to maintain appropriate anaesthetic depth. Quality of induction was scored from 1 (poor) to 3 (smooth) and basic cardiorespiratory variables were recorded every 5 minutes during anaesthesia. Results are reported as mean ± standard deviation or median (range) as appropriate.

Results

Sedation scores were 9 (7–10). Inductions were smooth in all pigs and cardiovascular variables remained within normal limits for the duration of anaesthesia. The induction dose of alfaxalone was 0.9 (0.0–2.3) mg kg?1. Three pigs did not require additional alfaxalone after premedication to facilitate intubation.

Conclusions and clinical relevance

Intramuscular alfaxalone in combination with medetomidine and butorphanol produced moderate to deep sedation in pigs. Alfaxalone produced satisfactory induction and maintenance of anaesthesia with minimal cardiovascular side effects. Appropriate monitoring of pigs premedicated with this protocol is required as some pigs may become anaesthetized after intramuscular administration of this combination of drugs.  相似文献   

7.

Objective

To determine the intubation dose and select physiologic effects of alfaxalone alone or in combination with midazolam or ketamine in dogs.

Study design

Prospective, clinical study.

Animals

Fifty-three healthy client-owned dogs [mean ± standard deviation (SD)] 5.1 ± 1.8 years, 27 ± 15.4 kg, scheduled for elective orthopedic surgery.

Methods

After premedication with acepromazine (0.02 mg kg–1) and hydromorphone (0.1 mg kg–1) intramuscularly, alfaxalone (0.25 mg kg–1) was administered intravenously over 15 seconds followed immediately by 0.9% saline (AS), midazolam (0.3 mg kg–1; AM), ketamine (1 mg kg–1; AK1), or ketamine (2 mg kg–1; AK2). Additional alfaxalone (0.25 mg kg–1 increments) was administered as required to permit endotracheal intubation. The incidence of apnea and the time from intubation until spontaneous movement were recorded. Heart rate (HR) and blood pressure were recorded 15 minutes after premedication, after intubation and 2, 5, 10 and 15 minutes thereafter. Blood was collected for measurement of serum glucose and insulin concentrations before induction, after intubation and at 2, 5, 10 and 50 minutes. Data were analyzed by split-plot anova with Bonferroni adjustment for the number of group comparisons.

Results

Mean ± SD alfaxalone mg kg–1 doses required for endotracheal intubation were AS (1.0 ± 0.4), AM (0.4 ± 0.2), AK1 (0.5 ± 0.3) and AK2 (0.5 ± 0.4) (p = 0.0005). Differences in cardiopulmonary variables among groups were minor; HR decreased in AS, while in other groups, HR increased transiently postintubation. Incidence of apnea in AS was 54% with no significant difference among groups. Midazolam significantly prolonged time from intubation until spontaneous movement (p < 0.002).

Conclusions and clinical relevance

Midazolam and ketamine reduced the alfaxalone dose required for endotracheal intubation. Serum glucose and insulin concentrations were not influenced by administration of alfaxalone alone or when administered with midazolam or ketamine.  相似文献   

8.

Objective

To compare the effect of propofol and alfaxalone on laryngeal motion under a light plane of anaesthesia in nonbrachycephalic and brachycephalic dogs anaesthetized for nonemergency procedures.

Study design

Prospective, randomized clinical trial.

Animals

A total of 48 client-owned dogs (24 nonbrachycephalic and 24 brachycephalic).

Methods

A standardized premedication of methadone (0.2 mg kg?1) and acepromazine (0.01 mg kg?1) was administered intramuscularly. Dogs were randomly assigned to be induced with increments of propofol (1–4 mg kg?1) or alfaxalone (0.5–2 mg kg?1). Laryngeal assessment was performed under a light plane of anaesthesia by a surgeon (GTH) who was unaware of the induction protocol. Laryngeal movement was assessed as either being present when abduction of the laryngeal cartilages upon inspiration was identified, or absent when abduction was not recognized. Simultaneously, a 60-second video was recorded. The same surgeon (GTH) and an additional surgeon (NK) re-evaluated the videos 1 month later. Categorical comparisons were studied using Chi square and Fisher’s exact test where appropriate. Pairwise evaluation of agreement between scorers was undertaken with the kappa statistic (κ).

Results

There were no significant differences (p > 0.05) identified between the presence or absence of laryngeal motion between dogs administered propofol or alfaxalone, as well as when analysing nonbrachycephalic and brachycephalic dogs separately. The majority of dogs (>75%) maintained some degree of laryngeal motion with both protocols. Agreement between assessors was excellent (κ = 0.822).

Conclusions

Alfaxalone maintained laryngeal motion similarly to propofol in nonbrachycephalic and brachycephalic dogs.

Clinical relevance

Both agents would appear appropriate for allowing assessment of laryngeal motion in nonbrachycephalic and brachycephalic dogs. The assessment technique of subjective evaluation of laryngeal motion via peroral laryngoscopy under a light plane of anaesthesia produced consistent results amongst assessors, regardless of the induction agent used.  相似文献   

9.

Objective

To evaluate the clinical effects and quality of sedation, induction, maintenance and recovery in Lemur catta after dexmedetomidine–butorphanol–midazolam sedation and alfaxalone anaesthesia.

Study design

Prospective, observational study.

Animals

Six male L. catta weighing 3.0 ± 0.6 kg undergoing surgical castration.

Methods

Lemurs were sedated with intramuscular dexmedetomidine (0.015 mg kg?1), butorphanol (0.2 mg kg?1) and midazolam (0.2 mg kg?1). Anaesthesia was induced with intravenous alfaxalone 0.5 mg kg?1 over 60 seconds; further boluses were administered until tracheal intubation was feasible and final dose recorded. Alfaxalone continuous infusion was used to maintain anaesthesia. Atipamezole (0.15 mg kg?1) was administered during recovery. The quality of sedation, induction, intubation, maintenance and recovery was assessed using a scoring system. Physiological parameters were recorded during sedation, maintenance and recovery.

Results

Sedation was achieved in 13.6 ± 5.6 minutes and no reactions were observed during handling or venepuncture. The mean dose of alfaxalone required for induction and maintenance was 2.09 ± 0.65 and 0.08 ± 0.02 mg kg?1 minute?1, respectively. Quality of induction, intubation and maintenance was good in almost all animals. Mild self-limiting muscle twitching was observed after alfaxalone administration in three animals. Cardiorespiratory function was stable in all animals but one. One lemur showed respiratory depression and required oxygen administration and manual ventilation. The mean maintenance time was 29.2 ± 7.4 minutes. The mean times from the end of alfaxalone administration to extubation, atipamezole administration and full recovery were: 15.3 ± 8.0, 22.2 ± 4.6 and 60.0 ± 8.4 minutes, respectively. Recovery was considered good in all animals.

Conclusions and clinical relevance

Dexmedetomidine–butorphanol–midazolam combination provided reliable sedation and adequate muscle relaxation in L. catta. Alfaxalone proved to be a useful drug for induction and maintenance of anaesthesia and might be considered an option for injectable anaesthesia in lemurs.  相似文献   

10.

Objective

To determine whether intratesticular injection of an alfaxalone–lidocaine combination can induce anesthesia and provide a rapid recovery in piglets undergoing surgical castration.

Study design

Randomized experimental study.

Animals

A group of 30 male piglets, aged 2–10 days, weighing 1.3–4.6 kg.

Methods

Animals were randomly divided into three equal groups for intratesticular administration of alfaxalone + lidocaine: high dose (group HD; 8 mg kg–1 + 2.5 mg kg–1), medium dose (group MD; 6 mg kg?1 + 2 mg kg?1) and low dose (group LD; 4 mg kg?1 + 1.5 mg kg?1). Induction and recovery times, movement and vocalization were recorded. Pulse rate (PR), oxygen saturation, respiratory rate (fR), rectal temperature, blood pressure and end-tidal carbon dioxide were recorded until recovery.

Results

Induction time did not differ significantly among groups (p = 0.19); mean time of 2.2, 3.3 and 3.7 minutes for HD, MD and LD, respectively. Recovery time to sternal recumbency was significantly faster in LD compared with HD and MD (p = 0.005). Time to standing was mean 34.1, 31.6 and 29.6 minutes for HD, MD and LD, respectively (p = 0.58). Incidences of movement and vocalization during the castration procedure were decreased in HD and MD compared with LD, but were not statistically different. There were no differences in the physiologic data among the groups except for PR, which decreased in all three groups (p < 0.05), and fR, which increased in MD and LD (p < 0.05).

Conclusions and clinical relevance

The alfaxalone–lidocaine combinations investigated in this study induced deep sedation in all piglets. Physiologic data remained within clinically acceptable ranges, suggesting that this drug combination by intratesticular injection prior to castration in neonatal piglets is well tolerated. The authors recommend the alfaxalone (6 mg kg?1) + lidocaine (2 mg kg?1) dose.  相似文献   

11.

Objective

To compare the performance of an alfaxalone constant rate intravenous (IV) infusion versus a 3-step IV infusion, both following a loading dose, for the maintenance of a target plasma alfaxalone concentration of 7.6 mg L–1 (effective plasma alfaxalone concentration for immobility in 99% of the population) in cats.

Study design

Prospective randomized crossover study.

Animals

A group of six healthy, adult male neutered cats.

Methods

Catheters were placed in a jugular vein for blood sampling and in a medial saphenous vein for drug administration. An IV bolus of alfaxalone (2 mg kg–1) was administered, followed by either 0.2 mg kg?1 minute?1 for 240 minutes (single infusion; SI) or 0.4 mg kg?1 minute?1 for 10 minutes, then 0.3 mg kg?1 minute?1 for 30 minutes, and then 0.2 mg kg?1 minute?1 for 200 minutes (3-step infusion; 3-step). Plasma alfaxalone concentration was measured at six time points during the infusions. Measures of performance were calculated for each infusion regimen and compared using the paired Wilcoxon signed-rank test.

Results

Median (range) absolute performance error, divergence, median prediction error and wobble were 15 (8–19)%, ?8 (?12 to ?6)% hour?1, ?12 (?19 to ?7)% and 10 (8–19)%, respectively, in the SI treatment, and 6 (2–16)%, 0 (?13 to 2)% hour?1, 1 (?16 to 4)% and 4 (3–6)% respectively, in the 3-step treatment and were significantly smaller in the 3-step treatment than in the SI treatment.

Conclusion and clinical relevance

After IV administration of a bolus dose, a 3-step infusion regimen can better maintain stable plasma alfaxalone concentrations close to the target concentration than a single constant rate infusion.  相似文献   

12.

Objective

To characterize alfaxalone administered subcutaneously (SC) in guinea pigs, both alone and in combination with dexmedetomidine and buprenorphine.

Study design

Prospective, blinded, crossover study.

Animals

A total of 15 healthy female guinea pigs weighing 400–600 g.

Methods

Alfaxalone (10, 20 and 40 mg kg?1) was administered SC to three guinea pigs as a pilot dose-finding study. Alfaxalone (20 mg kg?1; A20) was selected for comparison against combination protocols of alfaxalone (15 and 20 mg kg?1) with dexmedetomidine (0.25 mg kg?1) and buprenorphine (0.05 mg kg?1; A15DB, A20DB). Each protocol was randomly administered to 12 guinea pigs separated by ≥7 days. Time and quality of induction and recovery, heart rate, respiratory rate, peripheral hemoglobin oxygen saturation, rectal temperature, pedal withdrawal reflex and adverse effects were recorded.

Results

The median time to induction for A20, A15DB and A20DB was 6.8–8.0 minutes with no significant difference between treatments. Mean duration of recumbency for A20 was 73.6 ± 19.6 minutes. Recumbency duration for A15DB and A20DB extended to 90 minutes, at which time dexmedetomidine was antagonized using atipamezole (0.025 mg kg?1 SC). Physiological variables were within normal limits with the exception of one animal that died 45 minutes following treatment with A20DB. Pedal withdrawal reflex remained intact with all treatments. Minor side effects such as twitching or bruxism occurred sporadically with treatment A20 but not with A15DB and A20DB.

Conclusions and clinical relevance

SC alfaxalone produced uncomplicated sedation that may be recommended for nonpainful procedures that do not require complete immobility. The addition of dexmedetomidine and buprenorphine increased the duration of sedation and immobility, but did not result in general anesthesia. This combination sedation protocol may be useful for nonpainful procedures requiring extended immobility.  相似文献   

13.

Objective

To evaluate the efficacy and side effects of alfaxalone administered intramuscularly (IM) as a sedative agent in guinea pigs undergoing survey radiographs.

Study design

Prospective clinical trial.

Animals

A total of 30 client-owned guinea pigs.

Methods

Following baseline assessments, 5 mg kg?1 alfaxalone was administered IM. Heart rate, arterial haemoglobin oxygen saturation, respiratory rate, rectal body temperature, palpebral reflex, response to toe and ear pinch, righting reflex, posture, jaw tone and reaction to manipulation were assessed before and after sedation at 5-minute intervals. The time elapsed from onset of sedation to return of locomotion and coordinated limb movements, the quality of recovery and the occurrence of undesired effects were observed and recorded.

Results

The mean ± standard deviation onset of sedation was 2.7 ± 0.6 minutes. The physiological variables remained within normal ranges until completion of the procedure. Palpebral reflex and responsiveness to both ear and toe pinch were maintained during sedation. Neither hypoxaemia nor hypothermia was observed. The duration of sedation was 29.3 ± 3.2 minutes. Sedation and recovery were uneventful, and adverse effects were not observed.

Conclusions and clinical relevance

In conclusion, 5 mg kg?1 of IM alfaxalone represents a valuable sedation protocol for healthy guinea pigs undergoing minor noninvasive procedures. Further trials are required to investigate its cardiovascular effects, clinical usefulness in unhealthy patients and its combined use with analgesics for procedures associated with nociception.  相似文献   

14.

Objective

To determine the effects of two dexmedetomidine continuous rate infusions on the minimum infusion rate of alfaxalone for total intravenous anaesthesia (TIVA), and subsequent haemodynamic and recovery effects in Greyhounds undergoing laparoscopic ovariohysterectomy.

Study design

Prospective, randomized and blinded clinical study.

Animals

Twenty-four female Greyhounds.

Methods

Dogs were premedicated with dexmedetomidine 3 μg kg?1 and methadone 0.3 mg kg?1 intramuscularly. Anaesthesia was induced with IV alfaxalone to effect and maintained with a TIVA mixture of alfaxalone in combination with two different doses of dexmedetomidine (0.5 μg kg?1 hour?1 or 1 μg kg?1 hour?1; groups DEX0.5 and DEX1, respectively). The alfaxalone starting dose rate was 0.07 mg kg?1 minute?1 and was adjusted (± 0.02 mg kg?1 minute?1) every 5 minutes to maintain a suitable depth of anaesthesia. A rescue alfaxalone bolus (0.5 mg kg?1 IV) was administered if dogs moved or swallowed. The number of rescue boluses was recorded. Heart rate, arterial blood pressure and arterial blood gas were monitored. Qualities of sedation, induction and recovery were scored. Differences between groups were tested for statistical significance using a Student’s t test or Mann–Whitney U test as appropriate.

Results

There were no differences between groups in sedation, induction and recovery quality, the median (range) induction dose of alfaxalone [DEX0.5: 2.2 (1.9–2.5) mg kg?1; DEX1: 1.8 (1.2–2.9) mg kg?1], total dose of alfaxalone rescue boluses [DEX0.5: 21.0 (12.5–38.8) mg; DEX1: 22.5 (15.5–30.6) mg] or rate of alfaxalone (DEX0.5: 0.12 ± 0.04 mg kg?1 minute?1; DEX1: 0.12 ± 0.03 mg kg?1 minute?1).

Conclusions and clinical relevance

Co-administration of dexmedetomidine 1 μg kg?1 hour?1 failed to reduce the dose rate of alfaxalone compared with dexmedetomidine 0.5 μg kg?1 hour?1 in Greyhounds undergoing laparoscopic ovariohysterectomy. The authors recommend an alfaxalone starting dose rate of 0.1 mg kg?1 minute?1. Recovery quality was good in the majority of dogs.  相似文献   

15.

Objective

To investigate whether an intravenous (IV) lidocaine bolus in calves premedicated with xylazine-butorphanol reduces the amount of ketamine required to allow endotracheal intubation.

Study design

Randomized, prospective clinical study.

Animals

In total, 41 calves scheduled for elective umbilical surgery.

Methods

Calves were randomly assigned to one of two groups (L: lidocaine or S: saline). The calves were administered xylazine (0.07 mg kg?1) and butorphanol (0.1 mg kg?1) intramuscularly and 10 minutes later lidocaine (2 mg kg?1; group L) or saline (group S) IV over 1 minute. After 2 minutes, ketamine (2.5 mg kg?1) was injected IV. If the depth of anaesthesia was insufficient for intubation, additional ketamine (1 mg kg?1) was administered every minute until intubation was successful. The amount of ketamine required for intubation, respiratory rate, pulse rate, arterial pressures, the depth of sedation and conditions of endotracheal intubation after induction of anaesthesia were compared between the two groups.

Results

The calves in group L were sedated more deeply than those in group S; however, neither the median (range) amount of ketamine required for intubation, 3.5 (2.5–4.5) mg kg?1 and 3.5 (2.5–3.5) mg kg?1, respectively, nor the induction quality differed significantly between the groups.

Conclusion and clinical relevance

A bolus of lidocaine (2 mg kg?1) administered 10 minutes after xylazine-butorphanol in calves deepened the degree of sedation but did not decrease the requirement of ketamine for endotracheal intubation. No adverse effects were recorded in the physiological variables measured.  相似文献   

16.

Objective

To determine the minimum infusion rate (MIR) of alfaxalone required to prevent purposeful movement in response to standardized stimulation while co-administered with lidocaine at three different doses by constant infusion rate infusion (CRI) in goats.

Study design

Prospective, blinded, randomized crossover, experimental.

Animals

A total of eight healthy goats: four does and four wethers.

Methods

Anaesthetic induction was with lidocaine at 1 mg kg?1 [low dose of lidocaine (L-Lid)], 2 mg kg?1 [moderate dose (M-Lid)] or 4 mg kg?1 [high dose (H-Lid)] and alfaxalone at 2 mg kg?1. Anaesthetic maintenance was with alfaxalone initially at 9.6 mg kg?1 hour?1 combined with one of three lidocaine treatments: 3 mg kg?1 hour?1 (L-Lid), 6 mg kg?1 hour?1 (M-Lid) or 12 mg kg?1 hour?1 (H-Lid). The MIR of alfaxalone was determined by testing for responses to a stimulation in the form of clamping on a digit with a Vulsellum forceps every 30 minutes during lidocaine CRI. Basic cardiopulmonary parameters were measured.

Results

The alfaxalone MIRs were 8.64 (6.72–10.56), 6.72 (6.72–8.64) and 6.72 (6.72–6.72) mg kg?1 hour?1 during L-Lid, M-Lid and H-Lid, respectively, without any significant differences among treatments. Compared to the initial rate of 9.6 mg kg?1 hour?1, these reductions in MIR are equivalent to 10, 30 and 30%, respectively. Significant increases in heart rate (HR) and arterial carbon dioxide partial pressure (PaCO2) and decreases in arterial haemoglobin saturation (SaO2), arterial oxygen partial pressure (PaO2) and respiratory frequency (fR) immediately after induction were observed during all lidocaine treatments.

Conclusions and clinical relevance

Lidocaine reduces the alfaxalone MIR by up to 30% with a tendency towards a plateauing in this effect at high CRIs. Immediate oxygen supplementation might be required to prevent hypoxaemia.  相似文献   

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18.

Objective

To evaluate the anaesthetic effects of three different alfaxalone doses to induce anaesthesia in goldfish.

Study design

Prospective, randomized, clinical study.

Animals

Thirty goldfish undergoing skin scraping, gill examination and stool collection.

Methods

Each fish was transferred to an individual 4 L induction tank and randomly allocated into one of three groups (n = 10), in which alfaxalone was administered at concentrations of 6, 7 or 9 mg L–1. The depth of anaesthesia was evaluated by approach reaction, equilibrium, opercular movement and reaction to tactile stimuli. Sedation, light anaesthesia, surgical anaesthesia and recovery times were recorded. Data were analyzed with analysis of variance. A p value <0.05 was considered significant.

Results

Surgical anaesthesia was achieved in all fish. Goldfish induced with alfaxalone 7 and 9 mg L–1 showed a mild excitement phase. Time to sedation of the 6 mg L–1 dose (5.89 ± 0.40 minutes) was significantly longer compared to the 7 mg L–1 (3.97 ± 0.40 minutes) and 9 mg L–1 doses (3.94 ± 0.40 minutes). Times to light anaesthesia and surgical anaesthesia of the 9 mg L–1 dose (7.65 ± 1.04 and 9.60 ± 1.84 minutes, respectively) were significantly faster compared with those of the 6 mg L–1 dose (13.79 ± 1.04 and 19.75 ± 1.84 minutes, respectively) and the 7 mg L–1 dose (13.55 ± 1.04 and 21.24 ± 1.84 minutes, respectively). No significant differences were recorded in recovery time. Cessation of opercular movement was recorded in two fish induced with 7 mg L–1 and in two induced with 9 mg L–1. No mortality occurred.

Conclusions

and clinical relevance Alfaxalone is a reliable agent for immersion anaesthesia in goldfish. Immersion in water containing 6 mg alfaxalone L–1 provided smooth induction of anaesthesia, and no obvious side effects were encountered. Higher doses shortened induction time and caused respiratory depression and excitatory movements.  相似文献   

19.

Objective

To develop a modified ultrasound-guided parasacral approach to the sciatic nerve and compare the effects of a volume of 0.2 mL kg–1 of 0.5% levobupivacaine with an equivalent volume of 0.9% saline injected near the sciatic nerve.

Study design

Cadaveric and experimental, blinded, randomized study.

Animals

Seven canine cadavers and seven experimental Beagle dogs.

Methods

Both sciatic nerves of seven cadavers were identified using a modified in-plane ultrasound-guided approach. Methylene blue solution (0.2 mL) was injected perineurally, and success was evaluated through dissection. The same approach was repeated in seven Beagle dogs sedated with dexmedetomidine (50 μg kg–1) injected intramuscularly (IM). After randomization, 0.2 mL kg–1 of 0.5% levobupivacaine (limb L) and 0.2 mL kg–1 of 0.9% saline (limb C) were injected perineurally on either right or left limb. Block success was determined by sensory deficits every hour for 8 hours after an atipamezole injection (0.2 mg kg–1) IM. Reaction to pinprick (binary score) over the course of the sciatic nerve (four locations) and locomotion were assessed.

Results

The overall sciatic nerve block success was 93% in cadavers and 86% in sedated dogs. It was impossible to localize the sciatic nerves in one obese sedated dog. Significant differences between limb L and limb C were observed for pinprick at great trochanter, caudal thigh and lateral tarsal joint (p < 0.0001). Reaction to pinprick was absent in all dogs at great trochanter and caudal thigh up to at least 3 hours on limb L. Locomotion was impaired in all but one dog for 60 (30–210) minutes (median; interquartile range). No complications were observed.

Conclusions and clinical relevance

A volume of ≥0.2 mL kg–1 and a concentration of 0.5% levobupivacaine can be recommended when using a modified ultrasound-guided parasacral approach to the sciatic nerve in dogs.  相似文献   

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