Fentanyl or midazolam for co-induction of anaesthesia with propofol in dogs

ObjectivePropofol may cause adverse effects (e.g. apnoea, hypotension) at induction of anaesthesia. Co-induction of anaesthesia may reduce propofol requirements. The effect of fentanyl or midazolam on propofol dose requirements and cardiorespiratory parameters was studied.Study designRandomized, controlled, blinded clinical study.AnimalsSixty-six client owned dogs (35 male, 31 female, ASA I-II, age 6–120 months, body mass 4.7–48.0 kg) were selected.MethodsPre-medication with acepromazine (0.025 mg kg⁻¹) and morphine (0.25 mg kg⁻¹) was administered by intramuscular injection. After 30 minutes group fentanyl-propofol (FP) received fentanyl (2 μg kg⁻¹), group midazolam-propofol (MP) midazolam (0.2 mg kg⁻¹) injected over 30 seconds via a cephalic catheter and in a third group, control-propofol (CP), the IV catheter was flushed with an equivalent volume of heparinized saline. Anaesthesia was induced 2 minutes later, with propofol (4 mg kg⁻¹minute⁻¹) administered to effect. After endotracheal intubation anaesthesia was maintained with a standardized anaesthetic protocol. Pulse rate, respiratory rate (RR) and mean arterial pressure (MAP) were recorded before the co-induction agent, before induction, and 0, 2 and 5 minutes after intubation. Apnoea ≥30 seconds was recorded and treated. Sedation after pre-medication, activity after the co-induction agent, quality of anaesthetic induction and endotracheal intubation were scored.ResultsPropofol dose requirement was significantly reduced in FP [2.90 mg kg⁻¹(0.57)] compared to CP [3.51 mg kg⁻¹ (0.74)] and MP [3.58 mg kg⁻¹(0.49)]. Mean pulse rate was higher in MP than in CP or FP (p = 0.003). No statistically significant difference was found between groups in mean RR, MAP or incidence of apnoea. Activity score was significantly higher (i.e. more excited) (p = 0.0001), and quality of induction score was significantly poorer (p = 0.0001) in MP compared to CP or FP. Intubation score was similar in all groups.Conclusions and clinical relevanceFentanyl decreased propofol requirement but did not significantly alter cardiovascular parameters. Midazolam did not reduce propofol requirements and caused excitement in some animals.     

"氯-芬"合剂微泵法行小儿静脉麻醉的临床观察

探讨“氯－芬”合剂泵法行小儿静脉全麻的效果及其对患对患儿呼吸,循环的影响,方法５１例手术患儿,用“氯－芬”合剂微泵滴注行非插管全凭静脉麻醉,术中监测ＭＡＰ,ＨＲ,ＲＲ,ＳｐＯ２,定时查动脉血气。结论：“氯－芬”合剂微泵法可控性强,给药均匀且用量少,镇静镇痛完善,对呼吸循环影响轻微,术毕苏醒快,无明显并发症。     

山莨菪碱和芬太尼后处理联合缺血后适应对兔心肌缺血再灌注损伤SOD、MDA的影响

目的观察山莨菪碱和芬太尼后处理联合缺血后适应对心肌缺血再灌注兔心肌细胞氧化应激相关指标的影响。方法采用结扎兔左冠状动脉前降支30min、复灌120min建立心肌缺血再灌注模型。随机分为4组(n=8):假手术组:动脉下仅穿线不结扎;缺血再灌注组:直接恢复再灌注;缺血后适应组:结扎兔左冠状动脉前降支30min后予以3轮复灌30s/缺血30s的缺血后适应后恢复再灌注;联合用药后处理+缺血后适应组:缺血28min给予山莨菪碱5mg·kg-1、芬太尼5μg·kg-1后处理后,30min予以缺血后适应后恢复再灌注。检测各组心肌细胞超氧化物歧化酶酶蛋白活力浓度、丙二醛浓度。结果缺血再灌注组较假手术组外周血丙二醛浓度明显升高(P<0.01),超氧化物歧化酶酶蛋白活力明显降低(P<0.01)。缺血后适应组较缺血再灌注组外周血丙二醛浓度明显降低(P<0.01),超氧化物歧化酶酶蛋白活力浓度明显升高(P<0.01)。联合用药后处理+缺血后适应组较缺血后适应组外周血丙二醛浓度明显降低(P<0.01),超氧化物歧化酶酶蛋白活力明显升高(P<0.01)。结论心肌缺血再灌注可导致兔外周血丙二醛浓度升高,超氧化物歧化酶酶蛋白活力降低;缺血后适应可显著降低心肌缺血再灌注兔外周血丙二醛浓度,提高超氧化物歧化酶酶蛋白活力,其中山莨菪碱及芬太尼后处理联合心肌缺血后适应较之缺血后适应可显著降低心肌缺血再灌注兔外周血丙二醛浓度、提高超氧化物歧化酶酶蛋白活力,具有减轻心肌缺血再灌注损伤的作用。     

Effect of fentanyl on the induction dose and minimum infusion rate of alfaxalone preventing movement in dogs

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 (MIR_NM) in dogs.

Short term pharmacological immobilization in macaque monkeys

ObjectiveTo develop a safe and effective immobilization protocol in rhesus monkeys, which is not based on dissociative anaesthetic agent.Study designProspective, randomised, experimental trial.AnimalsTwenty rhesus monkeys, weighing 2.6–8.0 kg, 1–3 years of age, of both sexes.MethodsThe monkeys received 50 μg kg^?1 medetomidine, 0.25 mg kg^?1 midazolam and 5 μg kg^?1 fentanyl with 150 IU hyaluronidase intramuscularly (IM). The animals were closely observed for behavioural changes and reaction to sound stimulus. Pulse rate and oxygen saturation of haemoglobin (SpO₂) were monitored every 5 minutes, for 20 minutes. After this period, 250 μg kg^?1 atipamezole or a placebo was administered IM and behavioural changes were closely observed.ResultsFull immobilization was observed after mean 269 ± SD 116 seconds. Ten minutes after injection mean arterial oxygen saturation of haemoglobin was 94 ± 4%, but did not fall significantly further. The median pulse rate was 116 beats minute^?1 5 minutes after the administration of the drug. This level further decreased to a median level of 108 beats minute^?1 20 minutes after the drug's administration. The median time to recover from immobilization was significantly shorter after atipamezole administration when compared to placebo (2.7 versus 55 minutes). All animals awoke smoothly and no side effects such as vomiting or agitation were observed.ConclusionsShort term and reversible pharmacological immobilization was achieved using combination of midazolam, medetomidine, and fentanyl.Clinical relevanceThe present study demonstrates that 20-minute pharmacological immobilization with a combination of midazolam, medetomidine, and fentanyl is feasible in rhesus monkeys with minimal effect on heart rate.     

Regional differences in transdermal penetration of fentanyl through equine skin

The rate and regional differences for the penetration of fentanyl through equine skin was investigated in vitro using a commercial transdermal therapeutic system (TTS) or ‘patch’. Skin collected from the thorax, groin and leg (dorsal metacarpal) regions of five horses was placed in diffusion cells and a fentanyl TTS applied to each skin sample. Drug penetration through each skin sample over 48 h measured using high performance liquid chromatography (HPLC). Cumulative penetration (μg/cm²) was plotted against time (h) and used to regress the steady state flux (μg/cm²/h) of fentanyl through each skin site. Results showed similar fluxes for both the thorax (2.32 ± 0.17 μg/cm²/h and groin (2.21 ± 0.11 (μg/cm²/h) regions, but significantly lower flux (P = < 0.05) for the leg region (1.56 ± 0.120 μg/cm²/h. Interestingly, there was a significantly longer lag time for the penetration of fentanyl through the groin region (7.87 ± 0.51 h) compared to the other two sites (5.66 ± 0.97 h and 5.75 ± 0.43 h for the thorax and leg regions respectively). The results suggest that a fentanyl TTS applied to the leg region may have a small but significantly lower amount of fentanyl available systemically, compared to patches applied to the thorax or groin regions, which may affect the level of analgesia subsequently achieved in the horse.     

Anaesthetic and cardiorespiratory effects of a constant rate infusion of fentanyl in isoflurane‐anaesthetized sheep

ObjectiveTo determine the anaesthetic and cardiorespiratory effects of a constant rate infusion of fentanyl in sheep anaesthetized with isoflurane and undergoing orthopaedic surgery.Study designProspective, randomised, ‘blinded’ controlled study.AnimalsTwenty healthy sheep (weight mean 41.1 ± SD 4.5 kg).MethodsSheep were sedated with intravenous (IV) dexmedetomidine (4 μg kg⁻¹) and morphine (0.2 mg kg⁻¹). Anaesthesia was induced with propofol (1 mg kg⁻¹ minute⁻¹ to effect IV) and maintained with isoflurane in oxygen and a continuous rate infusion (CRI) of fentanyl 10 μg kg⁻¹ hour⁻¹ (group F) or saline (group P) for 100 minutes. The anaesthetic induction dose of propofol, isoflurane expiratory fraction (Fe’iso) required for maintenance and cardiorespiratory measurements were recorded and blood gases analyzed at predetermined intervals. The quality of recovery was assessed. Results were compared between groups using t-tests or Mann–Whitney as relevant.ResultsThe propofol induction dose was 4.7 ± 2.4 mg kg⁻¹. Fe’iso was significantly lower (by 22.6%) in group F sheep than group P (p = 0). Cardiac index (mean ± SD mL kg⁻¹ minute⁻¹) was significantly (p = 0.012) lower in group F (90 ± 15) than group P (102 ± 35). Other measured cardiorespiratory parameters did not differ statistically significantly between groups. Recovery times and recovery quality were statistically similar in both groups.Conclusions and clinical relevanceFentanyl reduced isoflurane requirements without clinically affecting the cardiorespiratory stability or post-operative recovery in anaesthetized sheep undergoing orthopaedic surgery.     

The effect of fentanyl on the end‐tidal sevoflurane concentration needed to prevent motor movement in dogs

ObjectiveThe objectives of this study were to determine the effects of fentanyl on the end-tidal concentration of sevoflurane needed to prevent motor movement (MAC_NM) in response to noxious stimulation, and to evaluate if acute tolerance develops.Study designRandomized cross-over experimental study.AnimalsSix healthy, adult (2–3 years old), intact male, mixed-breed dogs weighing 16.2 ± 1.1 kg.MethodsSix dogs were randomly assigned to receive one of three separate treatments over a 3 week period. After baseline sevoflurane MAC_NM (MAC_NM-B) determination, fentanyl treatments (T) were administered as a loading dose (Ld) and constant rate infusion (CRI) as follows: T1-Ld of 7.5 μg kg^?1 and CRI at 3 μg kg^?1 hour^?1; T2-Ld of 15 μg kg^?1 and CRI at 6.0 μg kg ^?1 hour^?1; T3-Ld of 30 μg kg^?1 and CRI at 12 μg kg^?1 hour^?1. The MAC_NM was defined as the minimum end-tidal sevoflurane concentration preventing motor movement. The first post-treatment MAC_NM (MAC_NM-I) determination was initiated 90 minutes after the start of the CRI, and a second MAC_NM (MAC_NM-II) determination was initiated 3 hours after MAC_NM-I was established.ResultsThe overall least square mean MAC_NM-B for all groups was 2.66%. All treatments decreased (p < 0.05) MAC_NM, and the decrease from baseline was 22%, 35% and 41% for T1, T2 and T3, respectively. Percentage change in T1 differed (p < 0.05) from T2 and T3; however, T2 did not differ from T3. MAC_NM-I was not significantly different from MAC_NM-II within treatments.Conclusions and clinical relevanceFentanyl doses in the range of 3–12 μg kg^?1 hour^?1 significantly decreased the sevoflurane MAC_NM. Clinically significant tolerance to fentanyl did not occur under the study conditions.