Constant Rate Infusion Of Lidocaine Research Articles

Evaluating the Efficacy of a Peripheral Nerve Simulator-Guided Brachial Plexus Block in Rabbits Undergoing Orthopaedic Surgery Compared to Systemic Analgesia.

Locoregional anaesthetic techniques are invaluable for providing multimodal analgesia for painful surgical procedures. This prospective, randomised study describes a nerve stimulator-guided brachial plexus blockade (BPB) in rabbits undergoing orthopaedic surgery in comparison to systemic lidocaine. Premedication was provided with intramuscular (IM) medetomidine, fentanyl, and midazolam. Anaesthesia was induced (propofol IV) and maintained with isoflurane. Nine rabbits received a lidocaine BPB (2%; 0.3 mL kg-1), and eight received a lidocaine constant rate infusion (CRI) (2 mg kg-1 IV, followed by 100 µg kg-1 min-1). Rescue analgesia was provided with fentanyl IV. Carprofen was administered at the end of the surgery. Postoperative pain was determined using the Rabbit Grimace Scale (RGS) and a composite pain scale. Buprenorphine was administered according to the pain score for two hours after extubation. Rabbits were filmed during the first two hours to measure distance travelled and behaviours. Food intake and faeces output were compared. Every rabbit in CRI required intraoperative rescue analgesia compared to none in BPB. However, rabbits in both groups had similar pain scores, and there was no difference in the administration of postoperative analgesia. There were no significant differences in food intake or faeces production over 18 h, and no significant differences in distance travelled or behaviours examined during the first two hours. BPB seems superior for intraoperative analgesia. Postoperatively, both groups were comparable.

Lidocaine constant rate infusion improves the probability of survival in rabbits with gastrointestinal obstructions: 64 cases (2012-2021).

To determine the survival to discharge rate of rabbits with gastrointestinal obstructions treated with lidocaine constant rate infusion (CRI) and other factors associated with survival. Cases of gastrointestinal obstruction in rabbits (n = 56, including 64 events) that had presented to a veterinary teaching hospital from 2012 to 2021. This was a retrospective study in which data on rabbits with evidence of gastrointestinal obstruction were extracted from veterinary teaching hospital medical records over a 9-year period. Systemic lidocaine treatment, breed, sex, age, temperature at presentation, blood glucose at presentation, and time to discharge or death were evaluated with univariate and multivariate logistic regression to identify factors significantly associated with survival to hospital discharge in rabbits with gastrointestinal obstruction. Comparatively, 89.7% of rabbits treated with lidocaine CRI (n = 39) survived to hospital discharge, while only 56% of rabbits that were not treated with lidocaine CRI (25) survived. In the final multivariate analysis, 2 factors were associated with survival to discharge: rabbits treated with systemic lidocaine and male rabbits had increased odds of survival compared to those not treated with systemic lidocaine and female rabbits, respectively. Results demonstrated that rabbits with gastrointestinal obstruction and treated with a lidocaine CRI were more likely to survive compared to rabbits not treated with lidocaine CRI.

Prophylactic use of a lidocaine constant rate infusion versus saline in dogs undergoing balloon valvuloplasty for management of pulmonic stenosis: A randomized control trial

ObjectiveTo evaluate the effect of a prophylactic lidocaine constant rate infusion (CRI) on the incidence and malignancy of catheter-induced ventricular ectopic complexes (VECs) during balloon valvuloplasty for management of pulmonic stenosis in dogs. Study designSingle-centre, prospective, randomized study. AnimalsClient-owned dogs (n = 70) with pulmonic stenosis. MethodsDogs were randomly assigned to one of two anaesthetic protocols: administration of lidocaine 2 mg kg–1 bolus followed by a CRI (50 μg kg–1 minute–1; group LD) or a saline placebo (group SL) during balloon valvuloplasty. All dogs were premedicated with methadone (0.3 mg kg–1) intramuscularly and a digital three-lead Holter monitor was applied. Anaesthetic co-induction was performed with administration of alfaxalone (2 mg kg–1) and diazepam (0.4 mg kg–1), and anaesthesia was maintained with isoflurane vaporised in 100% oxygen. CRIs were started on positioning of the dog in theatre and discontinued as the last vascular catheter was removed from the heart. All dogs recovered well and were discharged 24 hours postoperatively. Blinded Holter analysis was performed by an external veterinary cardiologist using commercially available dedicated analysis software; p < 0.05. ResultsOf the 70 dogs enrolled in the study, 61 were included in the final analysis: 31 in group LD and 30 in group SL.There was no significant difference between sinus beats (p = 0.227) or VECs (p = 0.519) between groups. In group LD, 19/31 (61.3%) dogs had a maximum ventricular rate ≥250 units and 20/30 (66.7%) dogs in group SL (p = 0.791). Conclusion and clinical relevanceIn this study, the use of a prophylactic lidocaine bolus followed by CRI in dogs undergoing balloon valvuloplasty for management of pulmonic stenosis did not significantly decrease the incidence nor the malignancy of VECs during right heart catheterization compared with a saline CRI.

Concentrations and kinetics of renal biomarkers in dogs with gastric dilatation-volvulus with and without 24-h intravenous lidocaine.

Gastric dilatation volvulus (GDV) can lead to organ failure including acute kidney injury (AKI). Due to its cytoprotective, antioxidant and anti-inflammatory effects, lidocaine has a potential to prevent AKI in dogs with GDV. Prospective, observational cohort study in client-owned dogs with GDV. To determine concentrations of renal biomarkers for AKI in dogs with GDV with and without intravenous (IV) lidocaine therapy. Thirty-two dogs were randomized to receive either IV lidocaine (2 mg/kg, followed by a lidocaine constant rate infusion at a dose of 50 μg/kg/min over 24 h; n = 17) or no lidocaine (n = 15). Blood and urine samples were taken at admission (T 0) (only blood), during or immediately after surgery (T 1), and 24 (T 24) and 48 (T 48) h after surgery. Plasma creatinine (pCr), plasma neutrophil gelatinase-associated lipocalin (pNGAL), urinary NGAL (uNGAL), uNGAL to creatinine ratio (UNCR), and urinary gamma-glutamyl transferase to creatinine ratio (uGGT/uCr) were evaluated. Biomarker concentrations were compared between dogs with and without IV lidocaine and the course of each marker was determined in comparison to its admission value. In the entire population, a significantly higher pCr at T 0 (median, 95 μmol/L, interquartile range, 82-105) compared with T 1 (69 μmol/L, 60-78), T 24 (63 μmol/L, 52-78), and T 48 (78 μmol/L, 65-87) (P < 0.001) was found. Plasma NGAL increased significantly between T 0 (5.66 ng/mL, 3.58-7.43) and T 24 (7.50 ng/mL, 4.01-11.89) (P = 0.006) and T 48 (9.86 ng/mL, 5.52-13.92) (P < 0.001), respectively. Urinary NGAL increased significantly between T 1 (0.61 ng/mL, 0.30-2.59) and T 24 (2.62 ng/mL, 1.86-10.92) (P = 0.001) and T 48 (4.79 ng/mL, 1.96-34.97 (P < 0.001), respectively. UNCR increased significantly between T 1 (0.15 μg/mmol, 0.09-0.54) and T 24 (1.14 μg/mmol, 0.41-3.58) (P = 0.0015) and T 48 (1.34 μg/mmol, 0.30-7.42) (P < 0.001), respectively. Concentrations of uGGT/uCr increased significantly from T 0 highest at T 24 (6.20 U/mmol, 3.90-9.90) and significantly decreased at T 48 (3.76 U/mmol, 2.84-6.22) (P < 0.001). No significant differences in any renal biomarker concentration were found between dogs with and without IV lidocaine therapy. Plasma NGAL, uNGAL and UNCR remained increased up to 48 h post-surgery. No evidence of lidocaine-associated renoprotection was found.

Neuromuscular blockade with atracurium for ophthalmic surgery in horses-Effects on surgical and anesthetic characteristics and recovery quality.

To study the surgical, anesthetic and recovery qualities of horses receiving either a neuromuscular blocking agent (atracurium) or intravenous lidocaine (treatment groups A and L, respectively). A total of thirty horses presented for ocular surgery were used in this study. Horses were randomly assigned to receive either atracurium (group A) or a lidocaine constant rate infusion (group L). Surgical quality was graded on a scale from 1 (excellent)-5 (poor). While anesthetized, the heart rate, oxygen saturation and mean arterial blood pressure, and end-expiratory carbon dioxide and desflurane concentration were monitored and recorded every 5minutes. Recovery was scored on a scale from 10 (best)-115 (worst). Horses in treatment group A needed significantly less desflurane then horses in treatment group L (p=0.04). Horses in treatment group A had a significantly better surgery score of 1 (1-2) (median and range) then horses in treatment group L (2.5; 1-5) (p=0.02). The quality of recovery was significantly better in horses in treatment group A compared with treatment group L, and horses needed significantly less time to reach the standing position. Atracurium and lidocaine CRI are safe methods of anesthesia for equine patients undergoing ocular surgery. Horses receiving atracurium needed less desflurane and had better surgery and recovery scores than horses receiving a lidocaine constant rate infusion.

Studies to Evaluate the Safety of Constant Rate Infusions of Dexmedetomidine, Ketamine and Lidocaine Alone or in Combination during Isoflurane Anesthesia in Horses

Background: Horses mount a huge stress response to anesthesia when compared to other animals, hence are risky candidates for anesthesia. Inhalant anesthetic agents offer more control to anesthetic depth and facilitate rapid recovery, hence are considered to be safer than intravenous agents for surgical procedures requiring more than an hour, however, newer drug combinations are being explored to minimize the undesired consequences and dose rate of inhalant agents. The present study explored the safety of dexmedetomidine, ketamine and lidocaine constant rate infusion alone or as a combination along with Isoflurane for safer anesthesia in horses.Methods: The study was conducted on 28 horses divided into S, D, DK and DKL groups having 7 animals in each. Xylazine (1 mg/kg) and butorphanol (0.05mg/kg) were given intravenously for premedication. Ketamine (2 mg/kg) and midazolam (0.2 mg/kg) were used for induction and anesthesia was maintained with isoflurane. Normal saline (1000ml/hour), Dexmedetomidine (2µg/kg/hr), Dexmedetomidine and ketamine (2 µg/kg/hr and 2 mg/kg/hr) and Dexmedetomidine, ketamine and lidocaine (2 µg/kg/hr, 2 mg/kg/hr and 2 mg/kg/h) were given as CRI in groups S, D, DK and DKL, respectively. Thiopentone sodium (250mg bolus, 5%) was given as a fast intravenous bolus whenever required. Anesthetic efficacy was evaluated based on clinical, haemato-biochemical, hemodynamic, and endocrine variables.Result: A significant decline in mean arterial pressure was noticed in group DKL but changes in CVP and SpO2 in different groups were non-significant. Higher Blood glucose and low Insulin levels were seen in group DK during 45-60 min. Constant rate infusions of Dexmedetomidine, Ketamine and Lidocaine alone or in combination produced a significant sparing effect on Isoflurane and thiopentone while they improved peri-operative quality of anesthesia in horses.

Constant Rate Infusion of Lidocaine, Tumescent Anesthesia and Their Combination in Dogs Undergoing Unilateral Mastectomy.

Simple SummaryAppropriate pain management, particularly when large tissue is removed, allows for better recovery during the postoperative period. The analgesic effects of regional tumescent anesthesia (TUM) combined with constant rate infusion (CRI) of lidocaine were evaluated in dogs submitted to unilateral mastectomy. The purpose of this study was to evaluate if the addition of TUM to lidocaine CRI influenced cardiopulmonary function in dogs undergoing unilateral mastectomy and provided adequate postoperative analgesia. The authors concluded that the combination of the two technique decreases pain and requirement for rescue analgesia than with lidocaine CRI or TUM alone.Tumescent anesthesia (TUM) is a technique that was initially used to perform liposuction under local anesthesia, which consists of the injection of such large volumes of local anesthetic until to produce swelling and firmness (tumescence) of the surgical area. The aim of this study was to compare the intraoperative analgesic efficacy of lidocaine (LID) constant rate infusion (CRI), of TUM, or their combination (LID/TUM) and the postoperative pain and analgesic requirement in dogs undergoing unilateral mastectomy. Twenty-four dogs were premedicated with dexmedetomidine (3 μg/kg) and methadone (0.2 mg/kg) intravenously (IV). After induction with propofol IV to effect, dogs were randomly allocated to receive a loading dose of lidocaine (2 mg/kg) followed by a CRI of 100 μg/kg/min (Group LID) in addition to an equivalent volume of lactated Ringer’s solution instead of local TUM; a loading dose of lactated Ringer’s solution followed by a CRI of Ringer’s solution in addition to TUM (Group TUM); a loading dose of lidocaine (2 mg/kg) followed by a CRI of 100 μg/kg/min in addition to TUM (Group LID/TUM). Anesthesia was maintained with isoflurane in oxygen. Postoperative pain scores were assessed once the dogs had fully recovered from the sedative effects, and following 15, 30, 45 and 60 min. The results of the current study allow us to assert that all three treatments provided satisfactory intraoperative antinociceptive effects but administration of LID/TUM induced greater inhibition on sympathetic stimulating effect up to 60 min from recovery, thus, providing better early postoperative pain relief in dogs undergoing mastectomy.

Use of intravenous lidocaine to treat dexmedetomidine-induced bradycardia in sedated and anesthetized dogs

ObjectiveTo assess cardiopulmonary function in sedated and anesthetized dogs administered intravenous (IV) dexmedetomidine and subsequently administered IV lidocaine to treat dexmedetomidine-induced bradycardia. Study designProspective, randomized, crossover experimental trial. AnimalsA total of six purpose-bred female Beagle dogs, weighing 9.1 ± 0.6 kg (mean ± standard deviation). MethodsDogs were randomly assigned to one of three treatments: dexmedetomidine (10 μg kg–1 IV) administered to conscious (treatments SED1 and SED2) or isoflurane-anesthetized dogs (end-tidal isoflurane concentration 1.19 ± 0.04%; treatment ISO). After 30 minutes, a lidocaine bolus (2 mg kg–1) IV was administered in treatments SED1 and ISO, followed 20 minutes later by a second bolus (2 mg kg–1) and a 30 minute lidocaine constant rate infusion (L-CRI) at 50 (SED1) or 100 μg kg–1 minute–1 (ISO). In SED2, lidocaine bolus and L-CRI (50 μg kg–1 minute–1) were administered 5 minutes after dexmedetomidine. Cardiopulmonary measurements were obtained after dexmedetomidine, after lidocaine bolus, during L-CRI and 30 minutes after discontinuing L-CRI. A mixed linear model was used for comparisons within treatments (p < 0.05). ResultsWhen administered after a bolus of dexmedetomidine, lidocaine bolus and L-CRI significantly increased heart rate and cardiac index, decreased mean blood pressure, systemic vascular resistance index and oxygen extraction ratio, and did not affect stroke volume index in all treatments. Conclusion and clinical relevanceLidocaine was an effective treatment for dexmedetomidine-induced bradycardia in healthy research dogs.

Total intravenous anaesthesia in a goat undergoing craniectomy

BackgroundCerebral coenurosis is a disease of the central nervous system in sheep and goats, and is usually fatal unless surgical relief is provided. Information regarding neuroanaesthesia in veterinary medicine in goats is scant.Case presentationWe describe anaesthetic management of an intact female goat (2 years; 16 kg) presented for craniectomy. The goat was sedated with xylazine (0.05 mg kg−1, i.m.) and morphine (0.05 mg kg−1, i.m.). General anaesthesia was induced 20 min later with propofol and maintained with a constant rate infusion of propofol (0.2 mg kg−1 min−1). A cuffed endotracheal tube was placed and connected to a rebreathing (circle) system and mechanical ventilation with 100% oxygen was initiated. A bolus of lidocaine (1 mg kg−1), midazolam (0.25 mg kg−1) and fentanyl 2.5 μg kg−1 was delivered via the intravenous route followed immediately by a constant rate infusion of lidocaine (50 μg kg−1 min−1), midazolam (0.15 mg kg−1 h−1) and fentanyl (6 μg kg−1 h−1) administered via the intravenous route throughout surgery. Craniectomy was undertaken and the goat recovered uneventfully.ConclusionTotal intravenous anaesthesia with propofol, lidocaine, fentanyl and midazolam could be an acceptable option for anaesthesia during intracranial surgery in goats.

Evaluation of gastric emptying time, gastrointestinal transit time, sedation score, and nausea score associated with intravenous constant rate infusion of lidocaine hydrochloride in clinically normal dogs.

OBJECTIVE To quantify nausea and sedation scores, gastric emptying time, and gastrointestinal transit time after IV administration of a lidocaine hydrochloride bolus followed by a constant rate infusion (CRI) in clinically normal dogs. ANIMALS 6 Beagles. PROCEDURES In a crossover study, dogs were fed thirty 1.5-mm barium-impregnated spheres (BIPS) and received a saline (0.9% NaCl) solution bolus (0.05 mL/kg) IV (time 0) followed by a CRI at 10 mL/h, a lidocaine bolus (1 mg/kg) IV followed by a CRI at 25 μg/kg/min, or a lidocaine bolus (1 mg/kg) IV followed by a CRI at 50 μg/kg/min; CRIs were for 12 hours. Nausea and sedation scores were assessed and abdominal radiographs obtained immediately after feeding of BIPS and every hour for 12 hours and again 16 hours after CRI start. Percentage of BIPSs in the small and large intestines, gastric emptying time, and gastrointestinal transit time were assessed. RESULTS Gastric emptying time did not differ significantly among treatments. Significantly more BIPS were in the large intestine 4 to 7 hours after treatment start for the 50-μg/kg/min treatment than for the other 2 treatments. Six hours after treatment start, significantly more BIPS were in the large intestine for the 25-μg/kg/min treatment than for the saline solution treatment. Higher sedation and nausea scores were associated with the 50-μg/kg/min CRI. CONCLUSIONS AND CLINICAL RELEVANCE In clinically normal dogs, lidocaine CRI did not significantly affect gastric emptying. However, gastrointestinal transit time was mildly decreased and sedation and nausea scores increased in dogs administered a lidocaine CRI at clinically used doses.

Anaesthetic management of a Baringo giraffe (Giraffa camelopardalis rotschildi) undergoing mandibular fracture repair on two occasions

A four-year-old zoo Baringo giraffe (Giraffa camelopardalis rothschildi) was anaesthetised twice for surgical repair of an open fracture of the right mandible. On both occasions, xylazine was administered intramuscularly via...

Comparison of the effects of an intravenous lidocaine infusion combined with 1% isoflurane versus 2% isoflurane alone on selected cardiovascular variables and recovery characteristics during equine general anaesthesia

ObjectivesTo compare the effects of a lidocaine constant rate infusion (CRI) combined with 1% isoflurane versus those of 2% isoflurane alone on cardiovascular variables in anaesthetized horses, and to estimate the sample size required to detect a difference in recovery quality. Study designProspective, randomized, blinded, crossover study. AnimalsTwelve healthy experimental horses. MethodsHorses were anaesthetized twice using an intravenous (IV) administration of acepromazine, romifidine, diazepam and ketamine. Horses were placed in dorsal recumbency and ventilated mechanically. During the first 10 minutes (P1), anaesthesia was maintained with a 2% inspired isoflurane fraction (FIIso). During the following 20 minutes (P2), horses received IV lidocaine (1.5 mg kg−1) (group IL) or saline (group I). During the last 60 minutes (P3), group IL received a lidocaine CRI (50 μg kg−1 minute−1 IV) and FIIso 1%, whereas group I received a saline CRI and FIIso 2%. Three weeks later, the horses received the alternative treatment. Painful stimuli were induced by introducing an 18 gauge needle intramuscularly. Ketamine and dobutamine requirements and physiological variables were recorded. Recoveries were assessed by two anaesthetists unaware of the treatment. Lidocaine plasma concentrations were measured during recovery. Data were analysed with anova. ResultsDuring P3, group IL had a lower heart rate (p = 0.002), higher mean arterial pressure (p < 0.001) and lower dobutamine requirement (p < 0.001) than group I. One horse had lidocaine plasma concentrations above toxic levels. Recoveries did not differ significantly between groups. Sample sizes of 208 horses in each group would be necessary to detect a statistically significant difference (85% statistical power) in recovery quality. Conclusions and clinical relevanceA lidocaine CRI combined with FIIso 1% rather than FIIso 2% alone may improve cardiovascular variables in healthy anaesthetized horses.

Effect of intraoperative constant rate infusion of lidocaine on short-term survival of dogs with septic peritonitis: 75 cases (2007–2011)

To investigate whether intraoperative administration of a lidocaine infusion to dogs with septic peritonitis was associated with short-term (48 hours) survival after surgery. Retrospective case series. 75 dogs with septic peritonitis. Medical records of dogs with septic peritonitis that underwent laparotomy between January 2007 and December 2011 at the Royal Veterinary College were reviewed. Select variables during the preoperative, intraoperative, and postoperative periods and short-term survival after surgery were compared between dogs that received an opioid only (group O; n = 33) and dogs that received lidocaine (50 μg/kg/min [22.7 μg/kg/min], IV; group L; 42) in addition to an opioid during surgery. The proportion of dogs that survived for 48 hours after surgery was significantly greater for group L (35/42) than for group O (20/33). Intraoperative infusion of lidocaine increased the odds of short-term survival (OR, 8.77; 95% CI, 1.94 to 39.57). No significant differences were observed between the 2 treatment groups for variables assessed during the preoperative and postoperative periods. During the intraoperative period, more dogs in group L received an IV bolus of a synthetic colloid than did dogs in group O, but the number of IV boluses administered was not associated with short-term survival. Results indicated that IV infusion of lidocaine might improve the short-term survival of dogs with septic peritonitis. Prospective clinical trials are necessary to determine the efficacy of lidocaine as a supportive treatment for dogs with septic peritonitis.

Evaluations of vital signs and echocardiographic left ventricular function after the constant rate infusion of lidocaine and/or ketamine in Beagle dogs

Evaluations of vital signs and echocardiographic left ventricular function after the constant rate infusion of lidocaine and/or ketamine in Beagle dogs

Clinical comparison of two regimens of lidocaine infusion in horses undergoing laparotomy for colic

ObjectiveTo compare, in horses undergoing laparotomy for colic, the effects of administering or not administering a loading intravenous (IV) bolus of lidocaine prior to its constant rate infusion (CRI). Effects investigated during isoflurane anaesthesia were end-tidal isoflurane concentration (Fe’ISO), cardiovascular function, anaesthetic stability and the quality of recovery. Study designProspective, randomized clinical study. AnimalsThirty-six client-owned horses. MethodsHorses were assigned randomly to receive lidocaine as a CRI (50 μg kg−1 minute−1) either preceded (LB) or not preceded (L) by a loading dose (1.5 mg kg−1 IV over 15 minutes). Lidocaine infusion (LInf) was started (T0) within 20 minutes after induction of general anaesthesia and discontinued approximately 30 minutes before the end of surgery. Anaesthetic depth, Fe’ISO, intra-operative physiological parameters and quality of recovery were assessed or measured. Data were analysed using one-way anova, t-test, Fisher test, Wilcoxon and Kruskal–Wallis tests as appropriate (p < 0.05). ResultsMean ± SD Fe’ISO was 1.21 ± 0.08% in group LB and 1.23 ± 0.06% in group L. Heart rate was significantly higher in group L than in group LB at times T5-T15, T25, T35 and T95. No difference was found between groups in other measured physiological values, nor in any measure taken to improve these parameters. Recovery phase was comparable and satisfactory in all but one full term pregnant horse in group L which fractured a femur during recovery. ConclusionPreloading with a lidocaine bolus prior to a CRI of lidocaine did not influence isoflurane requirements, cardiopulmonary effects (other than a reduction in heart rate at some time points) or recovery compared to no preloading bolus. Clinical relevanceA loading dose of lidocaine prior to CRI does not confer any advantage in horses undergoing laparotomy for colic.

Effects of lidocaine, dexmedetomidine or their combination on the minimum alveolar concentration of sevoflurane in dogs.

ABSTRACTThe aim of this study was to determine the effects of lidocaine (LIDO) and dexmedetomidine (DEX) or their combination (LIDO–DEX), administered by constant-rate infusion (CRI), on the minimum alveolar concentration (MAC) of sevoflurane in dogs. Seven healthy mongrel dogs were used with a 2-week washout interval between treatments in this study. Anesthesia was induced with propofol and maintained with sevoflurane in oxygen, and MAC of sevoflurane was determined after 90 min equilibration period in the dogs (SEV-MACBASAL). Then, sevoflurane MAC was determined again in the dogs after 45 min equilibration period of one of the following treatments: an intravenous loading dose of lidocaine 2 mg/kg followed by 6 mg/kg/hr CRI (SEV-MACLIDO); an intravenous loading dose of dexmedetomidine 2 µg/kg followed by 2 µg/kg/hr CRI (SEV-MACDEX); or their combination (SEV-MACLIDO-DEX). These SEV-MACs were determined in duplicate. Data were analyzed using ANOVA and post hoc Tuckey test when appropriate. The SEV-MACBASAL was 1.82 ± 0.06%, SEV-MACLIDO was 1.38 ± 0.08%, SEV-MACDEX was 1.22 ± 0.10%, and SEV-MACLIDO-DEX was 0.78 ± 0.06%. The CRI administration of lidocaine, dexmedetomidine and their combination produced a significant reduction in the MAC of sevoflurane by 26.1 ± 9.0% (P<0.0001), 43.7 ± 11.8% (P<0.0002) and 54.4 ± 9.8% (P<0.0001), respectively. The MAC reduction was significantly greater after the CRI combination of lidocaine and dexmedetomidine when compared with lidocaine CRI (P<0.0001) or dexmedetomidine CRI treatments (P<0.025).

Cardiorespiratory and antinociceptive effects of two different doses of lidocaine administered to horses during a constant intravenous infusion of xylazine and ketamine

BackgroundThis study investigated the antinociceptive effects of a constant rate infusion (CRI) of lidocaine during xylazine and ketamine anesthesia in horses and aimed to correlate these effects with cardiorespiratory variables, bispectral index (BIS) and plasma lidocaine concentrations. Six adult crossbred mares weighing 320–400 kg were anesthetized on three different occasions. Sedation was performed with xylazine (0.75 mg/kg IV) and anesthetic induction with guaifenesin (75 mg/kg IV) and ketamine (2 mg/kg IV). Anesthesia was maintained with 37.5 μg/kg/min of xylazine and 87.5 μg/kg/min of ketamine both administered intravenously for 75 min. The three treatments consisted of: lidocaine (loading dose: 5 mg/kg, CRI: 100 μg/kg/min; THL); lidocaine (loading dose: 2.5 mg/kg; CRI: 50 μg/kg/min: TLL); and saline (TS); all given 15 min after induction and maintained for 1 h. Antinociception was measured by response to electrical stimulation and bispectral index (BIS) was recorded during anesthesia. Parametric and non-parametric data were compared using ANOVA followed by Student-Newman-Keuls and Friedman tests, respectively.ResultsPlasma lidocaine concentrations peaked at the end of lidocaine loading dose and was greater in THL (9.61 ± 2.75 μg/mL) vs TLL (4.50 ± 3.34 μg/mL). Electrical noxious stimulation caused purposeful movement in all horses from TS, but no response in THL. The BIS was decreased in THL only and was less when compared to the other treatments throughout anesthesia. Blood pressure, PaO2 and PaCO2 increased and heart rate (HR), respiratory rate (RR), pH, total plasma protein and temperature decreased during anesthesia in all treatments. PaCO2 and HR were greater and RR and pH less in THL compared to TLL and TS at 30 min during anesthesia. All recoveries were considered excellent. Time to standing was longer after THL (60 ± 20 min) than following TLL and TS (32 ± 17 and 30 ± 15 min, respectively).ConclusionsAt the highest dose administered (THL) lidocaine CRI during xylazine/ketamine anesthesia decreased BIS and motor response to noxious stimulation, and prolonged recovery time without significant added cardiorespiratory depression.

Evaluation of lidocaine treatment on frequency of cardiac arrhythmias, acute kidney injury, and hospitalization time in dogs with gastric dilatation volvulus

To assess the efficacy of IV lidocaine in decreasing complication rate and improving the outcome in dogs with gastric dilatation volvulus (GDV). Prospective non-controlled study of 83 lidocaine-treated dogs with GDV compared to 47 untreated historical controls with GDV. University veterinary teaching hospital. One hundred and thirty client-owned dogs with naturally occurring GDV. Study group dogs were treated at presentation with lidocaine (2 mg/kg, IV bolus) followed by constant rate infusion (CRI) of 0.05 mg/kg/min for 24 h. Historical control dogs did not receive any lidocaine. There were no group differences in age, body weight, time lag from onset of clinical signs to presentation, rectal temperature and pulse rate at presentation, and proportion of gastric wall necrosis. The proportions of cardiac arrhythmias and acute kidney injury (AKI) were significantly (P< 0.001 and P = 0.045, respectively) lower in the lidocaine group (10/83 [12%] versus 18/47 [38.3%] and 3/83 [3.6] versus 0/47). Median hospitalization time period was shorter (P = 0.05) in the lidocaine group compared to the controls (median 48 h; range 24-360 h versus median 72 h; range 24-144 h, respectively). Early treatment with IV lidocaine bolus, followed by CRI of lidocaine for 24 h post presentation decreased the occurrence of cardiac arrhythmias, AKI and hospitalization time period significantly in lidocaine-treated dogs with GDV compared to untreated historical controls. Due to the nonblinded, placebo-uncontrolled, nonrandomized nature of the current study, further evaluation of the efficacy of lidocaine in dogs with GDV is warranted.

Effects of lidocaine constant rate infusion on sevoflurane requirement, autonomic responses, and postoperative analgesia in dogs undergoing ovariectomy under opioid-based balanced anesthesia

The effects of constant rate infusion (CRI) of lidocaine on sevoflurane (SEVO) requirements, autonomic responses to noxious stimulation, and postoperative pain relief were evaluated in dogs undergoing opioid-based balanced anesthesia. Twenty-four dogs scheduled for elective ovariectomy were randomly assigned to one of four groups: BC, receiving buprenorphine without lidocaine; FC, receiving fentanyl without lidocaine; BL, receiving buprenorphine and lidocaine; FL, receiving fentanyl and lidocaine. Dogs were anesthetized with intravenous (IV) diazepam and ketamine and anesthesia maintained with SEVO in oxygen/air. Lidocaine (2mg/kg plus 50 μg/kg/min) or saline were infused in groups BL/FL and BC/FC, respectively. After initiation of lidocaine or saline CRI IV buprenorphine (0.02 mg/kg) or fentanyl (4 μg/kg plus 8 μg/kg/h CRI) were administered IV in BC/BL and FC/FL, respectively. Respiratory and hemodynamic variables, drug plasma concentrations, and end-tidal SEVO concentrations (E'SEVO) were measured. Behaviors and pain scores were subjectively assessed 1 and 2h post-extubation. Lidocaine CRI produced median drug plasma concentrations <0.4 μg/mL during peak surgical stimulation. Lidocaine produced a 14% decrease in E'SEVO in the BL (P<0.01) but none in the FL group and no change in cardio-pulmonary responses to surgery or postoperative behaviors and pain scores in any group. Thus, depending on the opioid used, supplementing opioid-based balanced anesthesia with lidocaine (50 μg/kg/min) may not have any or only a minor impact on anesthetic outcome in terms of total anesthetic dose, autonomic responses to visceral nociception, and postoperative analgesia.

Evaluation of Nociception, Sedation, and Cardiorespiratory Effects of a Constant Rate Infusion of Xylazine Alone or in Combination with Lidocaine in Horses

This study aimed to evaluate the effects of a constant rate infusion (CRI) of xylazine or xylazine in combination with lidocaine on nociception, sedation, and physiologic values in horses. Six horses were given intravenous (IV) administration of a loading dose (LD) of 0.55 mg/kg of xylazine followed by a CRI of 1.1 mg/kg/hr. The horses were randomly assigned to receive three treatments, on different occasions, administered 10 minutes after initiation of the xylazine CRI, as follows: control, physiologic saline; lidocaine low CRI (LLCRI), lidocaine (LD: 1.3 mg/kg, CRI: 0.025 mg/kg/min); and lidocaine high CRI (LHCRI), lidocaine (LD: 1.3 mg/kg, CRI: 0.05 mg/kg/min). A blinded observer assessed objective and subjective data for 50 minutes during the CRIs. In all treatments, heart and respiratory rates decreased, end-tidal carbon dioxide concentration increased, and moderate to intense sedation was observed, but no significant treatment effect was detected in these variables. Ataxia was significantly higher in LHCRI than in the control treatment at 20 minutes of infusion. Compared with baseline values, nociceptive threshold increased to as much as 79% in the control, 190% in LLCRI, and 158% in LHCRI. Nociceptive threshold was significantly higher in LLCRI (at 10 and 50 minutes) and in LHCRI (at 30 minutes) than in the control treatment. The combination of CRIs of lidocaine with xylazine produced greater increases in nociceptive threshold compared with xylazine alone. The effects of xylazine on sedation and cardiorespiratory variables were not enhanced by the coadministration of lidocaine. The potential to increase ataxia may contraindicate the clinical use of LHCRI, in combination with xylazine, in standing horses.