The volume effect of lidocaine on thoracic epidural anesthesia in conscious Beagle dogs

ObjectiveTo evaluate the volume effect of local anesthetic solution on thoracic epidural analgesia in dogs.Study designProspective, experimental trial.AnimalsFive healthy adult Beagle dogs weighing 9.7 ± 1.3 kg.MethodsA catheter was inserted into the seventh thoracic epidural space using a lumbosacral approach, and secured with suture under total intravenous (IV) anesthesia with propofol. Each dog was administered four volume treatments (0.05, 0.10, 0.15 and 0.20 mL kg⁻¹) of 2% lidocaine via the catheter at 12 hour intervals. In every treatment, dogs were re-anesthetized with propofol (6 mg kg⁻¹, IV) and isoflurane, and received iohexol at each volume to visualize the epidural distribution (ED) through computed tomography. Three hours after epidurography, when dogs had recovered from anesthesia, the appropriate volume of lidocaine was injected through the catheter, and sensory blockade (SB) in dermatomes was evaluated by pinching with a mosquito forceps. Results were presented as median (range), and the volume effect on ED and SB was analyzed with one-way Kruskal–Wallis anova.ResultsIn proportion to volumes (0.05, 0.10, 0.15 and 0.20 mL kg⁻¹), there were significant increases in the extent of ED from 7.4 (5.5–9.0) to 10.4 (8.0–12.0), 13.2 (12.5–13.0), and 15.2 (13.0–18.0) vertebrae, respectively, p < 0.001, and in SB from 2.7 (1.0–5.0) to 6.8 (4.5–10.5), 9.9 (6.5–13.0), and 13.1 (11.0–15.0) dermatomes, respectively, p < 0.001. Unilateral ED and SB were observed in all treatments with various grades, and this distribution was more frequent in the low volume treatments. In the high volume treatments, temporary complications including Horner's syndrome, ataxia, paraplegia, depression, stupor, and intermittent cough occurred often.Conclusions and clinical relevanceThe increase in volume of local anesthetic solution improved SB by resulting in more consistent bilateral dermatome blockade as well as an extended blockade. However, caution should be exerted, as higher volume injections of lidocaine caused side effects in all dogs.     

Cardiovascular effects following epidural injection of romifidine in isoflurane‐anaesthetized dogs

ObjectiveTo investigate the cardiovascular effects of epidural romifidine in isoflurane-anaesthetized dogs.Study designProspective, randomized, blinded experiment.AnimalsA total of six healthy adult female Beagles aged 1.25 ± 0.08 years and weighing 12.46 ± 1.48 (10.25–14.50) kg.MethodsAnaesthesia was induced with propofol (6–9 mg kg^?1) and maintained with 1.8–1.9% end-tidal isoflurane in oxygen. End-tidal CO₂ was kept between 35 and 45 mmHg (4.7–6.0 kPa) using intermittent positive pressure ventilation. Heart rate (HR), arterial blood pressure and cardiac output (CO) were monitored. Cardiac output was determined using a LiDCO monitor and the derived parameters were calculated. After baseline measurements, either 10 μg kg^?1 romifidine or saline (total volume 1 mL 4.5 kg^?1) was injected into the lumbosacral epidural space. Data were recorded for 1 hour after epidural injection. A minimum of 1 week elapsed between treatments.ResultsAfter epidural injection, the overall means (± standard deviation, SD) of HR (95 ± 20 bpm), mean arterial blood pressure (MAP) (81 ± 19 mmHg), CO (1.63 ± 0.66 L minute^?1), cardiac index (CI) (2.97 ± 1.1 L minute^?1 m^?2) and stroke volume index (SI) (1.38 ± 0.21 mL beat^?1 kg^?1) were significantly lower in the romifidine treatment compared with the overall means in the saline treatment [HR (129 ± 24 bpm), MAP (89 ± 17 mmHg), CO (3.35 ± 0.86 L minute^?1), CI (6.17 ± 1.4 L minute^?1 m^?2) and SI (2.21 ± 0.21 mL beat^?1 kg^?1)]. The overall mean of systemic vascular resistance index (SVRI) (7202 ± 2656 dynes seconds cm^?5 m^?2) after epidural romifidine injection was significantly higher than the overall mean of SVRI (3315 ± 1167 dynes seconds cm^?5 m^?2) after epidural saline injection.ConclusionEpidural romifidine in isoflurane-anaesthetized dogs caused significant cardiovascular effects similar to those reportedly produced by systemic romifidine administration.Clinical relevanceSimilar cardiovascular monitoring is required after epidural and systemically administered romifidine. Further studies are required to evaluate the analgesic effects of epidural romifidine.     

Changes in endotracheal tube intracuff pressure and air leak pressure over time in anesthetized Beagle dogs

Objective

To evaluate endotracheal tube intracuff pressure (P_cuff) changes over time and the effect of these changes on air leak pressure (P_leak).

Effects of thoracolumbar epidural anesthesia with lidocaine on the systemic hemodynamics and hepatic blood flow in propofol anesthetized dogs

General anesthesia reduces hepatic blood flow (HBF) from circulatory depression. Total intravenous anesthesia (TIVA) is associated with decreased circulatory depression compared to inhalation anesthesia, and epidural anesthesia using local anesthetics increases blood flow by blocking the sympathetic nerves and expanding blood vessels. We investigated the effects of thoracolumbar epidural anesthesia with TIVA on HBF in dogs. Six Beagle dogs had epidural catheters placed between T13 and L1 and were anesthetized with propofol and vecuronium. Physiological saline (control) or 2% lidocaine (0.2 ml/kg, followed by 0.2 ml/kg/hr) was administered at 1–2 weeks intervals. Heart rate (HR), cardiac index (CI), mean arterial pressure (MAP), and systemic vascular resistance index (SVRI) were recorded at 10-min intervals from before epidural injections (T0) to 110 min. Indocyanine green test was used to measure HBF during the awake state and until 90 min after epidural injections. HR and CI did not differ between treatments. MAP and SVRI after lidocaine were significantly lower than those of controls, and the lowest MAP value was 65 ± 11 mmHg at T10. Compared to T0, after lidocaine treatment, HBF was significantly higher at T30, T60 and T90 (P<0.05); while, after control treatment, no significant change was evident at any time point. Despite a decrease in MAP by this technique, HBF was either maintained at pre-anesthetic levels or increased in comparison to controls, probably due to vasodilation of the hepatic artery induced by the selective blockade sympathetic ganglia.     

Identification of the sacrococcygeal epidural space using the nerve stimulation test or the running-drip method in dogs

ObjectiveTo compare the nerve stimulation test (group NS) with the running-drip method (group RUN) for successful identification of the sacrococcygeal (SCo) epidural space prior to drug administration in dogs.AnimalsA total of 62 dogs.Study designA randomized clinical study.MethodsDogs requiring an epidural anaesthetic as part of the multimodal anaesthetic plan were randomly allocated to one of the two study groups. In group NS, the epidural space was located using an insulated needle connected to a nerve stimulator; in group RUN, the epidural space was identified using a Tuohy needle connected to a fluid bag elevated 60 cm above the spine via an administration set. The success of the technique was assessed 5 minutes after epidural injection by the disappearance of the patella reflex. Data were checked for normality, nonparametric data was analysed using a Mann–Whitney U test and success rate was analysed using a Fisher’s exact test. The significance level was set at p < 0.05, and the results are presented in absolute values, percentage (95% confident interval) and median (range).ResultsThe success in identification of the epidural space did not differ between groups NS and RUN [87.1% (70.2%–96.4%) versus 90.3% (74.2%–98%); p = 1.000]. The time required for identification of the epidural space was shorter in group RUN [26 (15–53) seconds] than in group NS [40 (19–137) seconds] (p = 0.0225). No other differences were found in any studied variables.Conclusionand clinical relevance In this study, both RUN and NS techniques were successful in identifying the epidural space at the SCo intervertebral space. RUN requires no specialised equipment, can be performed rapidly and offers an alternative to the NS for use in general veterinary practice.     

Epidural anesthesia in dogs undergoing hindlimb orthopedic surgery: effects of two injection sites

This prospective clinical trial evaluated the effects of epidural anesthesia (EA) placed at the lumbosacral compared to the L5–L6 junction in dogs undergoing hindlimb orthopedic surgery. In all, 98 dogs were randomly assigned to receive injection at either L7–S1 (LS group) or L5–L6 (LL group) at the same local anesthetic regimen (1 mg/kg bupivacaine 0.5% and 0.1 mg/kg morphine 1%). Fentanyl (1 µg/kg) was the intraoperative rescue analgesia (iRA) administered if mean arterial pressure increased by 30% above pre-stimulation value. Procedural failure, iRA, hypotension, motor block resolution, and postoperative side effects were recorded. There were 7/47 (15%) epidural procedural failures in the LS group and 8/51 (16%) (P=1.00) in the LL group; iRA was administered in 21/40 (52%) LS group dogs and in 13/43 (30%) LL group dogs, respectively (P=0.047). The incidence of hypotension was 10/40 (25%) and 16/43 (37%) in the LS group and the LL group, respectively (P=0.25). Proprioceptive residual deficit at 8 hr after EA was recorded in 3/26 (12%) in group LS dogs and in 13/26 (50%) group LL dogs, respectively (P=0.01). The proprioceptive residual deficit at 24 hr in one dog (LL group) resolved within 36 hr. No episodes of postoperative urinary retention, pruritus or neurological damage were recorded. The L5–L6 EA decreased significantly iRA but delays the proprioceptive recovery time. Further studies are needed to determine whether a lower bupivacaine dose reduces the duration of the residual block retaining the same incidence of iRA.     

犬硬膜外阻滞对腹部手术应激的初步研究

8例犬间隔1个月分别施行2次腹部手术,第1次采用硬膜外阻滞(试验组,n=8),第2次采用硫喷妥钠静脉麻醉(对照组,n=8)。分别于麻醉前(T0)、麻醉后(T1)、切开腹壁时(T2)、手术30min(T3)、手术完毕时(T4)、手术后24h(T5)、手术后48h(T6)7个时间静脉采血,采用放射免疫法测定血浆皮质醇、白细胞介素-2浓度,采用比色法测定血糖浓度。结果:(1)对照组血浆皮质醇浓度平均值显著高于试验组(P<0·05),尤其在T3、T4时显著高于试验组(P<0·05)。对照组在T3、T4时血浆皮质醇浓度显著高于T0(P<0·05),而试验组各时间与T0比较均无显著差异(P>0·05);(2)对照组血浆白细胞介素-2浓度平均值极显著低于试验组(P<0·01),尤其在T1、T2、T5和T6时显著低于试验组。对照组在T5时、试验组在T3、T4时其血浆白细胞介素-2浓度均显著低于T0;(3)对照组血糖浓度平均值显著高于试验组,尤其在T4时显著高于试验组。对照组在T3、T4、T5和T6时、试验组则在T4时其血糖浓度均显著高于T0。结论:硬膜外阻滞组与硫喷妥钠静脉麻醉比较,硬膜外阻滞能够更有效缓解犬腹部手术的应激反应。     

The relationship of cataract maturity to intraocular pressure in dogs

Objective To determine the distribution of intraocular pressure, as measured by applanation tonometry, in dogs with cataracts, and compare these tonometric results to the different stages of cataract formation (incipient, immature, mature, and hypermature). Animals studied Retrospection study of canine clinical patients (86 dogs). Procedures All records of dogs presented from 1991 to 1996 to the university veterinary medical teaching hospital for diagnosis of cataracts and evaluation for cataract surgery were reviewed. The tonometric measurements from the initial ophthalmic examination were selected in cataractous and nonglaucomatous eyes either receiving no topical or no systemic medications. The stage of cataracts was based on the degree of opacification, tapetal reflection, clinical vision, and visibility of the ocular fundus by indirect ophthalmoscopy. The distribution of tonometric results were grouped by the cataract maturity, and compared by anova and Tukey’s general linear tests. Results Intraocular pressure with incipient cataracts ranged from 9 to 17 mmHg (mean 12.7 ± 1.2 mmHg). Intraocular pressure with immature cataracts ranged from 3 to 27 mmHg (mean 13.6 ± 0.6 mmHg). For the mature cataracts, IOP ranged from 5 to 22 mmHg (mean 11.9 ± 0.7 mmHg). For the hypermature cataract group, IOP ranged from 4 to 23 mmHg (mean 10.8 ± 0.6 mmHg). Comparison of the tonometric results among the different stages of cataract formation indicated a significant difference (P = 0.0086) between only the immature and hypermature groups. Conclusions Intraocular pressure in lens‐induced uveitis (LIU) is lowered but the relationship to the stage of cataract maturity is less clear. Significant tonometric differences were present between the immature and hypermature cataract groups, but these differences are too small to be clinically useful. Decreased intraocular pressure of dogs with all stages of cataract formation suggests concurrent LIU during all stages of cataract formation, especially with the mature and hypermature stages. The average tonometric measurements in dogs with these cataracts were about two standard deviations below the mean IOP reported in normal dogs.     

Distribution of intraocular pressure in dogs

Intraocular pressure (IOP) was measured by four different applanation tonometers in normal dogs. By MacKay-Marg tonometry in 391 dogs (772 eyes) the mean ± SD IOP was 18.8 ± 5.5 mmHg (range 8–52 mmHg). Using Tono-Pen XL tonometry in 421 dogs (823 eyes) the mean IOP was 19.2 ± 5.9 mmHg, and the range was 4.42 mmHg. With MMAC-II tonometry in 80 dogs (158 eyes), the mean IOP was 15.7 ± 2.8 mmHg with a range of 10–30 mmHg. By pneumatonograph tonometry in 135 dogs (255 eyes), the mean IOP was 22.9 ± 6.1 mmHg and the range was 10–47 mmHg. In this study 53 breeds were represented. Of those breeds with six animals or more, no significant differences were detected in IOP between breeds ( P > 0.353) or sex ( P > 0.270). There was a significant decline of 2–4 mmHg ( P > 0.0001) in IOP as age increased from less than 2 years to greater than 6 years of age. This trend was present with all of the four tonometers. There were no significant differences between the MacKay-Marg and TonoPen-XL tonometers ( P > 0.198), but significant differences with the MMAC-II ( P > 0.001) and pneumatonograph ( P > 0.001) tonometers existed compared to the first two instruments. Based on this study and the literature, the mean IOP for the normal dog is 19.0 mmHg with a range of 11 (5%) and 29 (95%) mmHg.     

Comparison of the effect of hypertonic hydroxyethyl starch and mannitol on the intraocular pressure in healthy normotensive dogs and the effect of hypertonic hydroxyethyl starch on the intraocular pressure in dogs with primary glaucoma

PURPOSE: The purpose of this study was to determine if intravenous hypertonic hydroxyethyl starch (7.5%/6%) (HES) could decrease the intraocular pressure (IOP) in healthy normotensive dogs, and compare its effect with that of mannitol (20%) (experimental study). In addition, the potential IOP-lowering effect of hypertonic HES was evaluated in six dogs with primary glaucoma (clinical study). MATERIAL AND METHODS: Experimental study: eight male ophthalmoscopically and clinically healthy Beagles were included in this study. The IOP of each dog was measured by applanation tonometry in both eyes to obtain control values at 10:00, 10:15, 10:30, 10:45, 11:00 a.m., and then every hour until 6:00 p.m. prior to the first treatment (control period). Each dog received, with at least 2-week intervals and in a random order, an intravenous (IV) infusion of 4 mL/kg hypertonic HES (1.2 g/kg NaCl; 0.96 g/kg HES) and 4 mL/kg mannitol 20% (1 g/kg) over a period of 15 min starting at 10:00 a.m. IOP was measured oculus uterque (OU) at the same time intervals as in the control study. The differences in IOP between the treatment groups and the baseline IOP (before the start of infusion), between oculus sinister (OS) and oculus dexter (OD) and between the same time points of all groups were determined with a Student's t-test for paired samples (P = 0.05). Clinical study: six dogs with primary glaucoma (representing seven eyes) received an IV infusion of 4 mL/kg hypertonic HES over a period of 15 min. IOP was measured before and 15 and 30 min after starting the infusion. RESULTS: Experimental study: no significant difference between IOP of both eyes was found. A significant decrease in IOP from baseline value was recorded at 15, 30, 45, and 60 min after the start of mannitol infusion (mean amplitude in IOP decrease 3.21 mmHg; P < 0.05) and at 15 and 30 min in dogs treated with HES (mean amplitude in IOP decrease 2.43 mmHg; P < 0.05). At 120 and 180 min there was a significantly higher IOP (P < 0.05) in HES treatment group compared to the values of the control group. Clinical study: in 5/7 eyes diagnosed with primary glaucoma a maximum decrease in IOP of an average of 24% from the baseline value (IOP before start of the infusion) was observed (range of decrease 2-21 mmHg). In three of these five cases the maximum decrease was reached at 15 min and in two cases at 30 min. In one case an increase in IOP of 35% (+ 18 mmHg) was seen after 15 min and 26% (+ 13 mmHg) after 30 min. Case 4 showed an increase in IOP of 5% (+ 3 mmHg) after 15 min and a decrease of 6% (- 4 mmHg) after 30 min. CONCLUSIONS: Intravenous hypertonic HES is comparable to intravenous mannitol 20% in lowering the intraocular pressure in healthy normotensive dogs. But this effect lasted half an hour longer after mannitol. In 6/7 eyes with primary glaucoma, hypertonic HES decreased IOP.     

Comparison of the hanging-drop technique and running-drip method for identifying the epidural space in dogs

Objective

To compare the running-drip and hanging-drop techniques for locating the epidural space in dogs.

Cardiovascular effects of epidural administration of methadone, ropivacaine 0.75% and their combination in isoflurane anaesthetized dogs

ObjectiveTo compare the cardiovascular effects of four epidural treatments in isoflurane anaesthetised dogs.Study designProspective, randomized. experimental study.AnimalsSix female, neutered Beagle dogs (13.3 ± 1.0 kg), aged 3.6 ± 0.1 years.MethodsAnaesthesia was induced with propofol (8.3 ± 1.1 mg kg^?1) and maintained with isoflurane in a mixture of oxygen and air [inspiratory fraction of oxygen (FiO₂) = 40%], using intermittent positive pressure ventilation. Using a cross-over model, NaCl 0.9% (P); methadone 1% 0.1 mg kg^?1 (M); ropivacaine 0.75% 1.65 mg kg^?1 (R) or methadone 1% 0.1 mg kg^?1 + ropivacaine 0.75% 1.65 mg kg^?1 (RM) in equal volumes (0.23 mL kg^?1) using NaCl 0.9%, was administered epidurally at the level of the lumbosacral space. Treatment P was administered to five dogs only. Cardiovascular and respiratory variables, blood gases, and oesophageal temperature were recorded at T-15 and for 60 minutes after epidural injection (T0).ResultsMean overall heart rate (HR in beats minute^?1) was significantly lower after treatment M (119 ± 16) (p = 0.0019), R (110 ± 18) (p < 0.0001) and RM (109 ± 13) (p < 0.0001), compared to treatment P (135 ± 21). Additionally, a significant difference in HR between treatments RM and M was found (p = 0.04). After both ropivacaine treatments, systemic arterial pressures (sAP) were significantly lower compared to other treatments. No significant overall differences between treatments were present for central venous pressure, cardiac output, stroke volume, systemic vascular resistance, oxygen delivery and arterial oxygen content (CaO₂). Heart rate and sAP significantly increased after treatment P and M compared to baseline (T-15). With all treatments significant reductions from baseline were observed in oesophageal temperature, packed cell volume and CaO₂. A transient unilateral Horner’s syndrome occurred in one dog after treatment R.Conclusions and clinical relevanceClinically important low sAPs were observed after the ropivacaine epidural treatments in isoflurane anaesthetised dogs. Systemic arterial pressures were clinically acceptable when using epidural methadone.     

Effect of orally administered hydrocortisone on intraocular pressure in nonglaucomatous dogs

OBJECTIVE: To determine the effect of oral hydrocortisone on intraocular pressure (IOP) in ocular normotensive dogs. ANIMALS STUDIED: Seventeen ocular normotensive dogs. Procedures Dogs were randomly assigned to treatment (n = 9) and control (n = 8) groups. Dogs in the treatment group received hydrocortisone, 3.3 mg/kg PO every 8 h, and dogs in the control group received gelatin capsule placebo PO every 8 h for 5 weeks. Applanation tonometry was performed on both eyes of all dogs prior to treatment and then once weekly for 5 weeks during hydrocortisone treatment. RESULTS: No significant effect of treatment was noted for right (P = 0.1013) or left (P = 0.1157) eyes during the treatment period, nor was there significant interaction of treatment by week for the right (P = 0.9456) or left (P = 0.3577) eyes. A significant rise in IOP over the treatment period was noted in both right (P < 0.0001) and left (P = 0.0006) eyes of both groups, but was unrelated to treatment. CONCLUSION: Orally administered hydrocortisone does not significantly increase IOP in nonglaucomatous dogs when administered over a 5-week period.     

利多卡因、布吡卡因行硬膜外阻滞对犬循环系统影响的研究

选择 1 4条健康的成年犬 ,随机分为 2组 ,利多卡因组 8只 ,布吡卡因组 6只。分别用 2 %利多卡因和 0 5 %布吡卡因行硬膜外阻滞麻醉 ,测定 2组心率和动脉压的变化 ,观察其对心血管系统的影响。结果 :利多卡因连续硬膜外阻滞下 ,犬心率在注药后 5min开始下降 ,下降最大幅度为基础值的 (82 8± 5 4) % ,但注药 1 0min后心率变化不明显 ;收缩压在 30min后下降到最低 ,降至基础值的 (84 3± 3 9) % ,舒张压在 45min下降至基础值的 (80 3± 6 6) %。布吡卡因组犬心率在注药后 30min下降到最低 ,平均为基础值的 (72 6± 7 6) % ;收缩压和舒张压在 30min下降至最低 ,但平均降幅分别为基础值的 (83 3± 2 8) %和 (82 2± 7 1 ) % ,而后缓慢上升。结论 :利多卡因硬膜外阻滞对犬的心率和动脉压没有明显影响 ;布吡卡因对犬的心率抑制作用较明显 ,但对动脉压没有明显影响。     

Effect of propofol and ketamine-diazepam on intraocular pressure in healthy premedicated dogs

Objective

To compare the effect of propofol and ketamine/diazepam for induction following premedication on intraocular pressure (IOP) in healthy dogs.

Cranial epidural spread of contrast medium and new methylene blue dye in sternally recumbent anaesthetized dogs

ObjectiveTo examine the spread of solution in the epidural space of sternally recumbent dogs.Study designProspective experimental trial.AnimalsTen healthy adult Beagle dogs weighing 7.6 ± 1.1 kg.MethodsDogs were anaesthetized with total intravenous propofol infusion, and placed in sternal recumbency. A volume of 0.2 mL kg^?1 contrast medium (CM) containing 1% new methylene blue (MB) dye was administered into the lumbosacral epidural space. Left to right lateral radiographs using a horizontal beam were taken every 5 minutes for 45 minutes. The perpendicular height (PH) between floor of the epidural canal of the highest vertebra and that of lumbosacral spinal canal was measured on radiographs. The angle of slope from the injection point toward the highest vertebral floor was measured. Immediately after taking the last radiographic image, dogs were euthanized and a laminectomy was performed from the cervical to lumbar vertebrae for visual evaluation of MB spread. The spread of CM and of MB as counted in number of stained vertebra were compared, and each of these data sets were further compared to PH and angle, using linear regression analyses.ResultsThe PH and angle were (mean ± SD) 3.8 ± 0.8 cm and 14.8 ± 2.8° respectively. The most cranial spread of CM was at 12.7 ± 5.7 (range: C6–L3) vertebrae, and at 14.0 ± 5.4 (range: C6–L2) vertebrae for MB staining. There were no significant correlations between PH and spread of CM (R² = 0.08) or MB (R² = 0.13), between angle and spread of CM (R² = 0.05) or MB (R² = 0.02), respectively. CM and MB demonstrated proportional relationship (R² = 0.82, p < 0.001).ConclusionsNo significant inhibitory effect of upward slope on cranial epidural spread of the solution was observed. Other factors may have greater effect on epidural spread in sternally recumbent dogs.