Influence of fentanyl on intra-abdominal pressure during laparoscopy in dogs

ObjectiveTo evaluate the influence of fentanyl on intra-abdominal pressures in spontaneously breathing dogs during capnoperitoneum.Study designProspective clinical study.AnimalsEleven healthy client-owned and five healthy experimental dogs undergoing laparoscopy.MethodsDogs were premedicated with acepromazine (0.03 mg kg^?1 IV) and carprofen (4 mg kg^?1 IV). Anaesthesia was induced with propofol and maintained with isoflurane in oxygen. The abdomen was insufflated with CO₂ (11–16 cm H₂O). Intra-abdominal pressures were measured with a transducer. Respiratory variables were measured with a spirometry sensor and side-stream capnography. Following preparation, fentanyl (1 μg kg^?1) was injected over 30 seconds IV. Data were recorded 5 minutes before, during and 5 minutes after treatment. The following time points were selected for statistical analysis (anova, p < 0.05): ?160, ?140, ?120, ?100, ?80, ?60, ?40, ?20, 0, 30, 50, 70, 90, 110, 130 and 150 seconds after the start of fentanyl injection.ResultsIntra-abdominal pressure increased during inspiration in 15 dogs but decreased in one dog. Fentanyl treatment did not alter these patterns. Peak inspiratory and end-expiratory intra-abdominal pressures continuously decreased over time during the whole experiment and fentanyl exaggerated the decrease in inspiratory pressures but did not affect the rate of decrease in expiratory pressures. Differences between intra-abdominal pressures were stable before, but decreased after fentanyl administration from 4.1 ± 1.4 to 3.3 ± 1.2 cm H₂O (at 0 and 150 seconds time points). End-tidal CO₂ partial pressures increased from 6.0 ± 0.8 to 6.6 ± 0.9 kPa, respiratory rate decreased from 10.8 ± 2.6 to 7.8 ± 2.2 breaths per minute and tidal volume decreased from 13.7 ± 4.4 to 12.4 ± 2.9 mL kg^?1 after fentanyl but these variables did not change before fentanyl treatment. Airway pressures did not change.Conclusions and clinical relevanceFentanyl did not increase intra-abdominal pressures in dogs.     

Chronotropic effect of propofol or alfaxalone following fentanyl administration in healthy dogs

ObjectiveTo compare the effect of alfaxalone and propofol on heart rate (HR) and blood pressure (BP) after fentanyl administration in healthy dogs.Study designProspective, randomised clinical study.AnimalsFifty healthy client owned dogs (ASA I/II) requiring general anaesthesia for elective magnetic resonance imaging for neurological conditions.MethodsAll dogs received fentanyl 7 μg kg⁻¹ IV and were allocated randomly to receive either alfaxalone (n = 25) or propofol (n = 25) to effect until endotracheal (ET) intubation was possible. Heart rate and oscillometric BP were measured before fentanyl (baseline), after fentanyl (Time F) and after ET intubation (Time GA). Post-induction apnoea were recorded. Data were analysed using Fisher’s exact test, Mann Whitney U test and one-way anova for repeated measures as appropriate; p value <0.05 was considered significant.ResultsDogs receiving propofol showed a greater decrease in HR (-14 beat minute⁻¹, range -47 to 10) compared to alfaxalone (1 beat minute⁻¹, range -33 to 26) (p = 0.0116). Blood pressure decreased over the three time periods with no difference between groups. Incidence of post-induction apnoea was not different between groups.ConclusionFollowing fentanyl administration, anaesthetic induction with propofol resulted in a greater negative chronotropic effect while alfaxalone preserved or increased HR.Clinical relevanceFollowing fentanyl administration, HR decreases more frequently when propofol rather than alfaxalone is used as induction agent. However, given the high individual variability and the small change in predicted HR (-7.7 beats per minute after propofol), the clinical impact arising from choosing propofol or alfaxalone is likely to be small in healthy animals. Further studies in dogs with myocardial disease and altered haemodynamics are warranted.     

Efficacy and cost-effectiveness of transdermal fentanyl patches for the relief of post-operative pain in dogs after anterior cruciate ligament and pelvic limb repair

OBJECTIVES: To determine whether transdermal fentanyl patches provided cost-effective post-operative analgesia in dogs with pelvic limb injuries. STUDY DESIGN: Prospective, randomized, blinded clinical trial. ANIMALS: Twenty-four dogs undergoing repair of ruptured cranial cruciate ligaments or pelvic limb fractures. METHODS: Dogs were randomly assigned to one of two groups: those receiving transdermal fentanyl patches (group F) and those receiving injectable morphine for control of post-operative pain (group M). Patients in both treatment groups were monitored for adequacy of analgesia and alterations in physiological variables. Plasma fentanyl concentrations were measured in Group F. Rescue morphine was given if a dog was deemed uncomfortable. The time of first rescue morphine, the total amount, and number of doses of morphine administered over 72 hours was quantified and compared for each group. RESULTS: There was no significant treatment effect on any of the parameters, except for serum cortisol concentration, which was significantly lower overall in group F (p = 0.01). Pain scores peaked at 6 hours post-extubation and were higher than baseline from 2 to 20 hours post-extubation. Cortisol concentrations were the highest at time 0 (extubation) and were significantly higher than baseline until 2 hours post-extubation. Pain scores correlated with fentanyl plasma concentrations (p = 0.0001 and p = 0.01, respectively), but the correlation was low (r = 0.26 and r = 0.16, respectively). No correlation was found between serum cortisol concentrations and pain scores in either group. Fentanyl cost and total cost for pain management were considerably higher for group F. CONCLUSIONS: Fentanyl patches did not provide better analgesia or a reduced requirement for rescue opioid compared with intramuscular morphine. CLINICAL RELEVANCE: When considering overall costs to the client for comparable analgesic intervention, fentanyl patches increased rather than decreased cost during the first 24 hours post-operatively.     

Postoperative respiratory effects of intravenous fentanyl compared to intravenous methadone in dogs following spinal surgery

Objective

To evaluate the 24-hour postoperative respiratory effects of either intravenous fentanyl administered as a constant rate infusion or boluses of methadone, in dogs following spinal surgery, assessed by serial arterial blood gas analyses.

Phenylpiperidine opioid effects on isoflurane minimum alveolar concentration in cats

Different structurally related phenylpiperidine opioids exhibit different isoflurane-sparing effects in cats. Because minimum alveolar concentration (MAC) in cats is affected only by very high plasma concentrations of some phenylpiperidine opioids, we hypothesized these effects are caused by actions on nonopioid receptors. Using a prospective, randomized, crossover design, six cats were anesthetized with isoflurane, intubated, ventilated, and instrumented. Isoflurane MAC was measured in triplicate using a tail-clamp and bracketing technique. A computer-controlled intravenous infusion using prior pharmacokinetic models targeted plasma concentrations of 60 ng/ml fentanyl, 10 ng/ml sufentanil, or 500 ng/ml alfentanil, and isoflurane MAC was measured in duplicate. Next, naltrexone 0.6 mg/kg was administered to cats hourly during the opioid infusion, and isoflurane MAC was measured in duplicate. Blood was collected during MAC determinations to measure opioid concentrations. Responses were analyzed using repeated measures ANOVA with significance at p < .05. Alfentanil and sufentanil decreased isoflurane MAC by 16.4% and 6.4%, respectively, and these effects were completely reversed by naltrexone. Fentanyl had no significant effect on isoflurane MAC. Alfentanil and sufentanil modestly reduce isoflurane MAC via agonist effects on opioid receptors. However, these effects are too small to justify clinical use of phenylpiperidine opioids as single agents to reduce MAC in cats.     

Comparison of transdermal fentanyl and oral tramadol for lateral thoracotomy in dogs: cardiovascular and behavioural data

Objective

To compare the analgesic efficacy and suitability of an existing oral tramadol-based protocol with a transdermal fentanyl-based protocol following lateral thoracotomy in dogs.

Inhibition and facilitation of nociceptively evoked muscular activity by fentanyl or dexmedetomidine in isoflurane-anaesthetized pigs

ObjectiveTo investigate motor and cardiovascular responses to dexmedetomidine or fentanyl in isoflurane-anaesthetized pigs.Study designExperimental, balanced, block randomized, two-group design.AnimalsA group of 16 crossbred pigs, 55 ± 8 days (mean ± standard deviation) old.MethodsDeltoid electromyography (EMG) was recorded during isoflurane anaesthesia. Electrical stimulation using 5, 10, 20 and 40 mA of the distal right thoracic limb elicited a nociceptive withdrawal reflex (NWR), quantified by the area under the curve (AUC) for the simulation intensity versus EMG amplitude response curve. Latency to movement evoked by clamping a claw for maximum 60 seconds was noted. Arterial blood pressure and pulse rate were recorded. Data were sampled at baseline and during dexmedetomidine 0.25, 0.5, 1.0, 2.0, 4.0 and 8.0 μg kg^–1 hour^–1 or fentanyl 5, 10, 20, 40, 80 and 160 μg kg^–1 hour^–1 infusions. The influence of infusion rate on NWR AUC and spontaneous EMG was analysed using a mixed model, with p < 5%.ResultsNWR AUC increased at fentanyl 5 μg kg^–1 hour^–1 but decreased at fentanyl 40, 80 and 160 μg kg^–1 hour^–1 and dexmedetomidine 4.0 and 8.0 μg kg^–1 hour^–1. All pigs at fentanyl 80 μg kg^–1 hour^–1, and three pigs at dexmedetomidine 8.0 μg kg^–1 hour^–1 had mechanical latencies greater than 60 seconds. Spontaneous EMG activity increased accompanied by visually evident ‘shivering’ at fentanyl 5, 10 and 20 μg kg^–1 hour^–1 but decreased at dexmedetomidine 2, 4 and 8 μg kg^–1 hour^–1. Clinically relevant effects of increasing infusion rates on blood pressure or pulse rate were not observed.Conclusion and clinical relevanceIf anaesthetic plane or antinociception is evaluated in pigs, response to claw clamping and NWR will not necessarily give uniform results when comparing drugs. If only one method is used, results should be interpreted cautiously.     

Effects of two fentanyl constant rate infusions on thermal thresholds and plasma fentanyl concentrations in awake cats

Objective

To determine the pharmacokinetics and effects on thermal thresholds (TT) of two fentanyl constant rate infusions in awake cats.

布比卡因、芬太尼、葡萄糖联合用于妇产科硬膜外术后镇痛的临床观察

目的：寻找一种硬膜外术后镇痛的合理药物或药物组合。方法；将31例妇产科手术后病人随机分为三级，分别从硬膜外注射0.125％的布比卡因10ml、0．125％的布比卡因＋10％葡萄糖10ml、0．125％的布比卡因＋10％葡萄糖＋0．05mg芬太尼10ml进行术后镇痛对照现实，并进行VAS、VRS评分及呼吸循环和并发症的监测。结果：三种药物联合应用效果明显优于其它对照经，具有起效快、镇痛完全、维持时间长、副作用少等优点。结论：三者联合是硬膜外术后镇痛的较好选择。