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Seddighi R, Geist A, Knych H, Sun X. The effect of remifentanil infusion on sevoflurane minimum alveolar concentration-no movement (MAC NM) and bispectral index in dogs. Vet Anaesth Analg 2023; 50:121-128. [PMID: 36641329 DOI: 10.1016/j.vaa.2022.12.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2022] [Revised: 12/13/2022] [Accepted: 12/13/2022] [Indexed: 12/24/2022]
Abstract
OBJECTIVE To determine the effect of remifentanil infusion on the minimum alveolar concentration of sevoflurane preventing movement (SEVOMACNM) and bispectral index (BIS) in dogs. STUDY DESIGN Prospective, unmasked study. ANIMALS A total of 10 adult Beagle dogs weighing 9.0 ± 1.1 kg. METHODS Dogs were anesthetized with sevoflurane and baseline SEVOMACNM was determined. Remifentanil was infused at 5, 10 and 20 μg kg-1 hour-1, in sequence, with 20 minutes washout between infusions. Variables monitored throughout anesthesia included heart rate (HR), oscillometric blood pressure, end-tidal partial pressure of carbon dioxide, end-tidal sevoflurane concentration (Fe'Sevo) and BIS. SEVOMACNM after remifentanil infusion (SEVOMACNM-REMI) determination started 20 minutes after the start of each infusion. Venous blood samples were collected for plasma remifentanil concentration determination at baseline, SEVOMACNM-REMI determination time points, and 20 minutes after each infusion was stopped. A mixed model analysis was used to determine the effect of remifentanil infusion on response variables. The relationships between BIS and Fe'Sevo, plasma remifentanil concentrations and the percentage decrease in baseline SEVOMACNM were evaluated (p < 0.05). RESULTS The overall SEVOMACNM at baseline was 2.47 ± 0.11%. Addition of remifentanil at all infusion rates significantly decreased SEVOMACNM, but the medium and high doses resulted in significantly greater decreases in SEVOMACNM than the lower dose. There was no difference in SEVOMACNM percentage change between infusions 10 and 20 μg kg-1 hour-1. Plasma remifentanil concentrations were significantly different in all infusion rates. Baseline BIS value was 70 ± 1 and was lower than the BIS values recorded during all remifentanil infusions. BIS values were not significantly different among infusion rates. HR was lower and mean arterial pressure was higher during remifentanil infusions than at baseline. CONCLUSIONS AND CLINICAL RELEVANCE All remifentanil infusions decreased SEVOMACNM in dogs. Remifentanil infusion at any rate studied did not reduce BIS values.
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Affiliation(s)
- Reza Seddighi
- Department of Large Animal Clinical Sciences, College of Veterinary Medicine, University of Tennessee, Knoxville, TN, USA.
| | - Anthony Geist
- Department of Biomedical and Diagnostic Sciences, College of Veterinary Medicine, University of Tennessee, Knoxville, TN, USA
| | - Heather Knych
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, CA, USA
| | - Xiaocun Sun
- Office of Information and Technology, University of Tennessee, Knoxville, TN, USA
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EVALUATION OF THE EFFECTS OF MIDAZOLAM AND FLUMAZENIL IN THE BALL PYTHON ( PYTHON REGIUS). J Zoo Wildl Med 2021; 50:579-588. [PMID: 33517626 DOI: 10.1638/2019-0024] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/14/2019] [Indexed: 11/21/2022] Open
Abstract
The study objective was to evaluate the sedative, muscle relaxant, and cardiorespiratory effects of midazolam and flumazenil in the ball python (Python regius). Ten healthy adult female ball pythons were used in a randomized and blinded crossover trial evaluating the effects of two dosages (1 and 2 mg/kg intramuscular [i.m.] in the cranial third of the body). In a subsequent open trial, nine ball pythons received 1 mg/kg i.m. of midazolam followed by 0.08 mg/kg i.m. of flumazenil 60 min later. Heart rate, respiratory rate, temperature, and the level of sedation and muscle relaxation (using a semiobjective scoring system) were evaluated. There were no significant differences between midazolam dosages for any of the parameters evaluated. Sedation scores were significantly increased compared with baseline from 15 min (1 mg/kg) and 10 min (2 mg/kg) postinjection up until 56 hr (1 mg/kg) and 72 hr (2 mg/kg) postinjection. Peak effect was reached 60 min postinjection, with 60% of snakes (6/10) being unable to right themselves. One snake developed paradoxical excitation with the 2 mg/kg dosage. Heart rates were significantly lower than baseline from 30 min to 128 hr postinjection with both midazolam dosages. Respiratory rates were significantly lower than baseline at four time points, with the highest dosage only: 15, 45, 60 min, and 8 hr postinjection. Flumazenil resulted in reversal of sedation and muscle relaxation in all snakes within 10 min of administration. However, resedation was evident in all snakes 3 hr after reversal. Midazolam administered at 1 and 2 mg/kg i.m. provides a moderate to profound, although prolonged, sedation and muscle relaxation in ball pythons. Flumazenil reverses the effects of midazolam in ball pythons, but its duration of action at the evaluated dosage is much shorter than midazolam, leading to resedation.
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The Determination of the Minimum Anaesthetic Concentration of Halothane in the Rock Dove (Columba livia) Using an Electrical Stimulus. BIRDS 2021. [DOI: 10.3390/birds2010006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
This study aims to determine the minimum anaesthetic concentration (MAC) of halothane in the Rock Dove using electrical stimulus. Seven Rock Doves are anaesthetised with halothane, and the MAC is determined using the bracketing method. An electrical stimulus (two single pulses and two five-second stimuli, all separated by five-second pauses; 30 Hz, 30 V, 7.5 ms) is applied to the legs via subcutaneous electrodes. A maximum of eight periods of electrical stimulation, each with a preceding 15 min stable phase, is applied to each bird. If the non-reflexive movement occurred following stimulation, the end-tidal halothane (Fe’Hal) is increased by 10% before the next stimulus delivery. If no movement occurred, Fe’Hal is decreased by 10%. The MAC is the average of the highest concentration that allowed movement and the lowest that prevented movement. Physiological variables and ventilatory settings are recorded every five minutes. The current delivered is calculated offline. The mean ± SD MAC of halothane is 1.62 ± 0.29%, calculated from five birds. During the entire anaesthesia, all birds had cardiac arrhythmias —with three having sporadic recurrent periods of prolonged ventricular standstill followed by marked sinus tachycardia. The mean recorded voltage and calculated current and resistance are 27.6 ± 2.7 V, 20.3 ± 7.3 mAmp and 1.6 ± 0.9 kΩ, respectively. The advantage of halothane for prolonged anaesthesia in Rock Doves may be limited when noxious stimulation is used, due to the development of severe ventricular arrhythmias.
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Henrique F, Pereira S, Batista L, Oliveira L, Monteiro N, Parentoni R, Souza A, Vaz A, Nóbrega Neto P. Anestesia intravenosa contínua com cetamina racêmica ou dextrocetamina e detomidina em cadelas. ARQ BRAS MED VET ZOO 2021. [DOI: 10.1590/1678-4162-11734] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
RESUMO Objetivou-se com este estudo comparar a associação de detomidina e cetamina ou dextrocetamina, por via intravenosa contínua, em oito cadelas submetidas a dois protocolos: GCD - indução anestésica com 5mg/kg e infusão intravenosa contínua de 20mg/kg/h de cetamina; e GDD - indução com 3,5mg/kg e infusão de 14mg/kg/h de dextrocetamina. Associou-se detomidina, 30µg/kg/h, em ambos os grupos. Registraram-se frequência cardíaca (FC), pressão arterial (PA), frequência respiratória (f), temperatura (TC), miorrelaxamento, analgesia, hemogasometria e eletrocardiograma, antes e 15 minutos após a MPA (Mbasal e Mmpa); após o início da infusão (Mic); a cada 10 minutos até 90 minutos (M10, M20, M30, M40, M50, M60, M70, M80 e M90); e 30 minutos após o fim da infusão (M120). Foi observada bradicardia em Mmpa no GCD e de Mmpa a M10 no GDD. Ocorreu hipotensão em Mmpa e hipertensão a partir de Mic. A f diminuiu de M10 a M30. Foram observados: onda T de alta amplitude, bloqueios atrioventriculares e parada sinusal. Ocorreu acidose respiratória. O período de recuperação foi de 219,6±72,3 minutos no GCD e de 234,1±96,8 minutos no GDD. A cetamina e a dextrocetamina, associadas à detomidina por infusão contínua, causam efeitos cardiorrespiratórios e anestésicos similares.
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Affiliation(s)
| | | | | | | | | | | | - A.P. Souza
- Universidade Federal de Campina Grande, Brazil
| | - A.F.M. Vaz
- Universidade Federal de Campina Grande, Brazil
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Cardiovascular effects of increasing dosages of norepinephrine in healthy isoflurane-anesthetized New Zealand White rabbits. Vet Anaesth Analg 2020; 47:781-788. [PMID: 32826161 DOI: 10.1016/j.vaa.2020.07.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2020] [Revised: 06/29/2020] [Accepted: 07/01/2020] [Indexed: 01/29/2023]
Abstract
OBJECTIVE To characterize the cardiovascular effects of increasing dosages of norepinephrine (NE) in healthy isoflurane-anesthetized rabbits. STUDY DESIGN Prospective experimental study. ANIMALS A total of nine female ovariohysterectomized New Zealand White rabbits weighing 3.4 ± 0.2 kg (mean ± standard deviation). METHODS Rabbits were premedicated intramuscularly with buprenorphine (0.05 mg kg-1) and midazolam (0.5 mg kg-1). Anesthesia was induced with intravenous propofol and maintained with a 1.1 × minimum alveolar concentration of isoflurane for this species to induce hypotension. Rabbits were administered NE infusions at three doses: low, 0.1 μg kg-1 minute-1; medium, 0.5 μg kg-1 minute-1; and high doses, 1 μg kg-1 minute-1 for 10 minutes each in that order. Cardiovascular variables including heart rate (HR), cardiac output (CO) by lithium dilution technique and systolic (SAP), mean (MAP) and diastolic (DAP) invasive arterial blood pressures measured in the auricular artery were recorded at baseline, 10 minutes after the start of the infusion of each NE treatment and 10 minutes after NE was discontinued. A linear mixed model and a type III anova with Tukey's post hoc comparison was performed (p < 0.05). RESULTS Significant increases in SAP (28% and 90%), MAP (27% and 90%) and DAP (33% and 97%) were measured with medium and high dose treatments, respectively (p < 0.001), with no changes in CO. HR decreased and stroke volume increased significantly with high dose treatment (by 17% and 15%, respectively; p < 0.05). No arrhythmias were noticed with NE treatments. CONCLUSIONS AND CLINICAL RELEVANCE The infusion of NE at 0.5-1.0 μg kg-1 minute-1 is a potentially effective treatment for hypotension in healthy isoflurane-anesthetized New Zealand White rabbits.
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Bustamante R, Gómez de Segura IA, Canfrán S, Aguado D. Effects of ketamine or midazolam continuous rate infusions on alfaxalone total intravenous anaesthesia requirements and recovery quality in healthy dogs: a randomized clinical trial. Vet Anaesth Analg 2020; 47:437-446. [PMID: 32340894 DOI: 10.1016/j.vaa.2019.10.010] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2019] [Revised: 09/18/2019] [Accepted: 10/06/2019] [Indexed: 11/19/2022]
Abstract
OBJECTIVE To determine the alfaxalone dose reduction during total intravenous anaesthesia (TIVA) when combined with ketamine or midazolam constant rate infusions and to assess recovery quality in healthy dogs. STUDY DESIGN Prospective, blinded clinical study. ANIMALS A group of 33 healthy, client-owned dogs subjected to dental procedures. METHODS After premedication with intramuscular acepromazine 0.05 mg kg-1 and methadone 0.3 mg kg-1, anaesthetic induction started with intravenous alfaxalone 0.5 mg kg-1 followed by either lactated Ringer's solution (0.04 mL kg-1, group A), ketamine (2 mg kg-1, group AK) or midazolam (0.2 mg kg-1, group AM) and completed with alfaxalone until endotracheal intubation was achieved. Anaesthesia was maintained with alfaxalone (6 mg kg-1 hour-1), adjusted (±20%) every 5 minutes to maintain a suitable level of anaesthesia. Ketamine (0.6 mg kg-1 hour-1) or midazolam (0.4 mg kg-1 hour-1) were employed for anaesthetic maintenance in groups AK and AM, respectively. Physiological variables were monitored during anaesthesia. Times from alfaxalone discontinuation to extubation, sternal recumbency and standing position were calculated. Recovery quality and incidence of adverse events were recorded. Groups were compared using parametric analysis of variance and nonparametric (Kruskal-Wallis, Chi-square, Fisher's exact) tests as appropriate, p < 0.05. RESULTS Midazolam significantly reduced alfaxalone induction and maintenance doses (46%; p = 0.034 and 32%, p = 0.012, respectively), whereas ketamine only reduced the alfaxalone induction dose (30%; p = 0.010). Recovery quality was unacceptable in nine dogs in group A, three dogs in group AK and three dogs in group AM. CONCLUSIONS AND CLINICAL RELEVANCE Midazolam, but not ketamine, reduced the alfaxalone infusion rate, and both co-adjuvant drugs reduced the alfaxalone induction dose. Alfaxalone TIVA allowed anaesthetic maintenance for dental procedures in dogs, but the quality of anaesthetic recovery remained unacceptable irrespective of its combination with ketamine or midazolam.
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Affiliation(s)
- Rocío Bustamante
- Department of Animal Medicine and Surgery, Veterinary Teaching Hospital, Veterinary Faculty, Complutense University of Madrid, Madrid, Spain
| | - Ignacio A Gómez de Segura
- Department of Animal Medicine and Surgery, Veterinary Teaching Hospital, Veterinary Faculty, Complutense University of Madrid, Madrid, Spain
| | - Susana Canfrán
- Department of Animal Medicine and Surgery, Veterinary Teaching Hospital, Veterinary Faculty, Complutense University of Madrid, Madrid, Spain
| | - Delia Aguado
- Department of Animal Medicine and Surgery, Veterinary Teaching Hospital, Veterinary Faculty, Complutense University of Madrid, Madrid, Spain.
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Minimum anesthetic concentration of isoflurane and sparing effect of midazolam in Quaker parrots (Myiopsitta monachus). Vet Anaesth Analg 2020; 47:341-346. [PMID: 32201049 DOI: 10.1016/j.vaa.2020.01.005] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2019] [Revised: 01/02/2020] [Accepted: 01/04/2020] [Indexed: 11/22/2022]
Abstract
OBJECTIVE To determine the effects of midazolam on the minimum anesthetic concentration (MAC) reduction of end-tidal isoflurane concentration (Fe'Iso) measured using an electrical stimulus in Quaker parrots (Myiopsitta monachus). STUDY DESIGN Randomized crossover experimental study. ANIMALS A group of six adult Quaker parrots, weighing 98-124 g. METHODS Birds were anesthetized with isoflurane in oxygen delivered by mask, then tracheally intubated and mechanically ventilated. Three treatments were applied with a 4 day interval between anesthetic events. Each anesthetized bird was administered midazolam (1 mg kg-1; treatment MID1), midazolam (2 mg kg-1; treatment MID2) or electrolyte solution (control) intramuscularly. The treatments were administered using a replicated Latin square design and the observers were blinded. Based on a pilot bird, the starting Fe'Iso was 1.8%. After equilibration for 10 minutes, a supramaximal stimulus was delivered using an electrical current (20 V and 50 Hz for 10 ms) and birds were observed for non-reflex movement. The Fe'Iso was titrated by 0.1% until a crossover event was observed. The MAC was estimated using logistic regression. RESULTS The MAC of isoflurane (MACISO) was estimated at 2.52% [95% confidence interval (CI), 2.19-2.85] with a range of 1.85-2.65%. MACISO in MID1 was 2.04% (95% CI, 1.71-2.37) and in MID2 was 1.81% (95% CI, 1.48-2.14); reductions in MACISO from control of 19% (p = 0.001) and 28% (p < 0.001), respectively. Heart rate, temperature, sex and anesthetic time were not different among treatments. CONCLUSIONS Midazolam (1-2 mg kg-1) intramuscularly resulted in a significant isoflurane-sparing effect in response to a noxious stimulus in Quaker parrots without observable adverse effects. CLINICAL RELEVANCE Midazolam can be used as part of a balanced anesthetic approach using isoflurane in Quaker parrots, and potentially in other psittacine species.
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Dholakia U, Seddighi R, Cox SK, Sun X, Pypendop BH. Pharmacokinetics of midazolam in sevoflurane-anesthetized cats. Vet Anaesth Analg 2019; 47:200-209. [PMID: 31983556 DOI: 10.1016/j.vaa.2019.11.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2019] [Revised: 11/20/2019] [Accepted: 11/23/2019] [Indexed: 11/28/2022]
Abstract
OBJECTIVE To estimate the pharmacokinetics of midazolam and 1-hydroxymidazolam after midazolam administration as an intravenous bolus in sevoflurane-anesthetized cats. STUDY DESIGN Prospective pharmacokinetic study. ANIMALS A group of six healthy adult, female domestic cats. METHODS Anesthesia was induced and maintained with sevoflurane. After 30 minutes of anesthetic equilibration, cats were administered midazolam (0.3 mg kg-1) over 15 seconds. Venous blood was collected at 0, 1, 2, 4, 8, 15, 30, 45, 90, 180 and 360 minutes after administration. Plasma concentrations for midazolam and 1-hydroxymidazolam were measured using high-pressure liquid chromatography. The heart rate (HR), respiratory rate (fR), rectal temperature, noninvasive mean arterial pressure (MAP) and end-tidal carbon dioxide (Pe'CO2) were recorded at 5 minute intervals. Population compartment models were fitted to the time-plasma midazolam and 1-hydroxymidazolam concentrations using nonlinear mixed effect modeling. RESULTS The pharmacokinetic model was fitted to the data from five cats, as 1-hydroxymidazolam was not detected in one cat. A five-compartment model best fitted the data. Typical values (% interindividual variability where estimated) for the volumes of distribution for midazolam (three compartments) and hydroxymidazolam (two compartments) were 117 (14), 286 (10), 705 (14), 53 (36) and 334 mL kg-1, respectively. Midazolam clearance to 1-hydroxymidazolam, midazolam fast and slow intercompartmental clearances, 1-hydroxymidazolam clearance and 1-hydroxymidazolam intercompartment clearance were 18.3, 63.5 (15), 22.1 (8), 1.7 (67) and 3.8 mL minute-1 kg-1, respectively. No significant changes in HR, MAP, fR or Pe'CO2 were observed following midazolam administration. CONCLUSION AND CLINICAL RELEVANCE In sevoflurane-anesthetized cats, a five-compartment model best fitted the midazolam pharamacokinetic profile. There was a high interindividual variability in the plasma 1-hydroxymidazolam concentrations, and this metabolite had a low clearance and persisted in the plasma for longer than the parent drug. Midazolam administration did not result in clinically significant changes in physiologic variables.
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Affiliation(s)
- Urshulaa Dholakia
- Department of Small Animal Clinical Sciences, College of Veterinary Medicine, University of Tennessee, Knoxville, TN, USA
| | - Reza Seddighi
- Department of Large Animal Clinical Sciences, College of Veterinary Medicine, University of Tennessee, Knoxville, TN, USA.
| | - Sherry K Cox
- Department of Biological and Diagnostic Services, College of Veterinary Medicine, University of Tennessee, Knoxville, TN, USA
| | - Xiaocun Sun
- Office of Information and Technology, University of Tennessee, Knoxville, TN, USA
| | - Bruno H Pypendop
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California, Davis, CA, USA
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Larouche CB, Johnson R, Beaudry F, Mosley C, Gu Y, Zaman KA, Beaufrère H, Dutton C. Pharmacokinetics of midazolam and its major metabolite 1-hydroxymidazolam in the ball python (Python regius) after intracardiac and intramuscular administrations. J Vet Pharmacol Ther 2019; 42:722-731. [PMID: 31469454 DOI: 10.1111/jvp.12806] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2019] [Revised: 07/07/2019] [Accepted: 07/31/2019] [Indexed: 11/28/2022]
Abstract
Midazolam is a benzodiazepine with sedative, muscle relaxant, anxiolytic, and anticonvulsant effects. Twelve ball pythons (Python regius) were used in a parallel study evaluating the pharmacokinetics of 1 mg/kg midazolam following a single intracardiac (IC) or intramuscular (IM) administration. Blood was collected from a central venous catheter placed 7 days prior, or by cardiocentesis, at 15 time points starting just prior to and up to 72 hr after drug administration. Plasma concentrations of midazolam and 1-hydroxymidazolam were determined by the use of high-performance liquid chromatography tandem-mass spectrometry and pharmacokinetic parameters were estimated using noncompartmental analysis. The mean ± SD terminal half-lives of IC and IM midazolam were 12.04 ± 3.25 hr and 16.54 ± 7.10 hr, respectively. The area under the concentration-time curve extrapolated to infinity, clearance, and apparent volume of distribution in steady-state of IC midazolam were 19,112.3 ± 3,095.9 ng*hr/ml, 0.053 ± 0.008 L hr-1 kg-1 , and 0.865 ± 0.289 L/kg, respectively. The bioavailability of IM midazolam was estimated at 89%. Maximum plasma concentrations following an IM administration were reached 2.33 ± 0.98 hr and 24.00 ± 14.12 hr postinjection for midazolam and 1-hydroxymidazolam, respectively, and 22.33 ± 20.26 hr postinjection for 1-hydroxymidazolam following IC administration.
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Affiliation(s)
- Cédric B Larouche
- Department of Pathobiology, Ontario Veterinary College, University of Guelph, Guelph, Ontario, Canada.,Toronto Zoo, Toronto, Ontario, Canada
| | - Ron Johnson
- Department of Biomedical Sciences, Ontario Veterinary College, University of Guelph, Guelph, Ontario, Canada
| | - Francis Beaudry
- Groupe de Recherche en Pharmacologie Animale du Québec (GREPAQ), Département de Biomédecine Vétérinaire, Faculté de Médecine Vétérinaire, Université de Montréal, Saint-Hyacinthe, Québec, Canada
| | - Craig Mosley
- VCA Canada, 404 Veterinary Emergency and Referral Hospital, Newmarket, Ontario, Canada
| | - Yu Gu
- Department of Biomedical Sciences, Ontario Veterinary College, University of Guelph, Guelph, Ontario, Canada
| | - Kristopher Afshaun Zaman
- Department of Pathobiology, Ontario Veterinary College, University of Guelph, Guelph, Ontario, Canada
| | - Hugues Beaufrère
- Department of Clinical Studies, Ontario Veterinary College, University of Guelph, Guelph, Ontario, Canada
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Larouche CB, Mosley C, Beaufrère H, Dutton C. Effects of midazolam and nitrous oxide on the minimum anesthetic concentration of isoflurane in the ball python (Python regius). Vet Anaesth Analg 2019; 46:807-814. [PMID: 31564503 DOI: 10.1016/j.vaa.2019.08.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2019] [Revised: 07/30/2019] [Accepted: 08/11/2019] [Indexed: 12/26/2022]
Abstract
OBJECTIVE To evaluate the effects of midazolam and nitrous oxide (N2O) on the minimum anesthetic concentration of isoflurane (MACISO) in ball pythons. STUDY DESIGN Prospective, crossover, randomized, semi-blinded study. ANIMALS A total of nine healthy adult female ball pythons (Python regius) weighing 2.76 ± 0.73 kg. METHODS In each snake, three protocols were evaluated with 2 week washouts: treatment MID-O2, midazolam (1 mg kg-1) administered intramuscularly (IM) and anesthesia induced with isoflurane-oxygen; treatment SAL-O2, saline (0.2 mL kg-1) IM and anesthesia with isoflurane-oxygen; and treatment SAL-N2O, saline IM and anesthesia with isoflurane and 50% nitrous oxide (N2O):50% oxygen. In each treatment, isoflurane was administered by face mask immediately after premedication. Snakes were endotracheally intubated and inspired and end-tidal isoflurane concentrations were monitored. The study design followed a standard bracketing technique, and the MACISO was determined using logistic regression. Electrical stimulation using a Grass stimulator connected to the base of the tail (50 V, 50 Hz, 6.5 ms pulse-1) was used as the supramaximal stimulus. Blood-gas analysis was performed on cardiac blood collected immediately following intubation and after the last stimulation. Blood-gas variables were compared over time and between treatments using linear mixed models. RESULTS MACISO at a body temperature of 30.1 ± 0.4 °C was 1.11% (95% confidence interval, 0.94-1.28%) in SAL-O2 and was significantly decreased to 0.48% (0.29-0.67%) in MID-O2 (p < 0.001) and to 0.92% (0.74-1.09%) in SAL-N2O (p = 0.016). PO2 was significantly lower in MID-O2 and SAL-N2O than in SAL-O2. CONCLUSIONS AND CLINICAL RELEVANCE Midazolam significantly decreased the MACISO by 57% in ball pythons, whereas addition of N2O resulted in a modest, although significant, decrease (17%). MACISO in ball pythons was lower than those previously reported in reptiles.
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Affiliation(s)
- Cédric B Larouche
- Toronto Zoo, Scarborough, ON, Canada; Department of Pathobiology, Ontario Veterinary College, University of Guelph, Guelph, ON, Canada.
| | - Craig Mosley
- VCA Canada, 404 Veterinary Emergency and Referral Hospital, Newmarket, ON, Canada
| | - Hugues Beaufrère
- Department of Clinical Studies, Ontario Veterinary College, University of Guelph, Guelph, ON, Canada
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Dholakia U, Seddighi R, Odunayo A, Cox SK, Jones EH, Pypendop BH. Prolonged Anesthetic Recovery after Continuous Infusion of Midazolam in 2 Domestic Cats ( Felis catus). Comp Med 2019; 69:321-326. [PMID: 31182185 DOI: 10.30802/aalas-cm-18-000145] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Two healthy research cats involved in a randomized, blinded prospective pharmacodynamics study evaluating midazolam continuous-rate infusion as a means to decrease sevoflurane concentrations experienced unexpectedly prolonged recoveries. Midazolam loading doses, infusion rates, and the targeted plasma midazolam concentrations at steady-state were determined by pharmacokinetic modeling based on the results of a preliminary pharmacokinetic study using a single dose of midazolam. In the pharmacodynamics study, cats remained oversedated after recovery from anesthesia, and plasma concentrations of midazolam and its primary metabolite (1-hydroxymidazolam) remained elevated. The use of flumazenil was unsuccessful in timely treatment of oversedation. Administration of intravenous lipid emulsion was used in one of the cats to facilitate recovery and appeared to be effective in both reducing the depth of midazolam-induced oversedation and significantly reducing the plasma concentration of 1-hydroxymidazolam. The effects after the administration of both treatment modalities on clinical signs and plasma drug concentrations in cats are discussed. The observations suggest that cats may eliminate 1-hydroxymidazolam more slowly than expected; consequently dose adjustments may be required when continuous infusion of midazolam is intended. In addition, intravenous lipid emulsion may facilitate recovery from midazolam oversedation, particularly in cases unresponsive to traditional treatment modalities. However, further investigations are warranted to delineate the efficacy of this modality in the treatment of midazolam oversedation.
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Kropf J, Hughes JL. Effect of midazolam on the quality and duration of anaesthetic recovery in healthy dogs undergoing elective ovariohysterectomy or castration. Vet Anaesth Analg 2019; 46:587-596. [PMID: 31395483 DOI: 10.1016/j.vaa.2019.05.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2018] [Revised: 03/28/2019] [Accepted: 05/03/2019] [Indexed: 11/18/2022]
Abstract
OBJECTIVE To determine whether the use of a single dose of midazolam affects quality and duration of the recovery period in healthy dogs undergoing elective castration or ovariohysterectomy. STUDY DESIGN Prospective, randomized, placebo-controlled, masked clinical trial. ANIMAL POPULATION Seventy-four client-owned dogs undergoing neutering. METHODS Following cage demeanour scoring using a simple descriptive scale (SDS), dogs were premedicated with acepromazine (0.03 mg kg-1) and pethidine (3 mg kg-1) intramuscularly (quadriceps muscle). Twenty minutes later sedation was scored with an SDS. Male dogs were induced with midazolam (0.25 mg kg-1) (group M) or an equivalent amount of Hartmann's solution (group P) and propofol intravenously (IV). Female dogs were induced with propofol alone and were administered midazolam (group M) or Hartmann's solution (group P) 5 minutes before intraoperative manipulation of the first ovary. Anaesthesia was maintained with isoflurane in oxygen. Intraoperative analgesia was provided with morphine (0.3 mg kg-1 IV) prior to the start of surgery. Male dogs were administered intratesticular lidocaine (1 mg kg-1). All dogs were administered meloxicam (0.2 mg kg-1 IV) at the end of the procedure, and recovery was scored with an SDS following extubation and 30 minutes later. Time to extubation, head lift, sternal position and standing and complications during recovery were recorded. Data are presented as median (range). RESULTS Time to standing was significantly longer in animals in group M [56 (13-179) minutes] than in group P [44 (4-137) minutes], and the early recovery score in group M [3 (2-6)] was overall worse than in group P [3 (1-5)]. Significantly more dogs in group M (n = 30) than in group P (n = 22) displayed hypotension. CONCLUSIONS AND CLINICAL RELEVANCE The administration of midazolam prolonged time to standing and had a mild negative effect on the quality of recovery in a pooled population of healthy male and female dogs undergoing neutering.
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Affiliation(s)
- Josephine Kropf
- Anaesthesia Department, Small Animal Hospital, School of Veterinary Medicine, University of Glasgow, Glasgow, UK.
| | - Jm Lynne Hughes
- Veterinary Anaesthesia, UCD Veterinary Hospital, UCD School of Veterinary Medicine, University College Dublin, Dublin, Ireland
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Lagos-Carvajal A, Queiroz-Williams P, da Cunha A, Liu CC. Determination of midazolam dose for co-induction with alfaxalone in sedated cats. Vet Anaesth Analg 2019; 46:299-307. [PMID: 30928240 DOI: 10.1016/j.vaa.2019.01.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2018] [Revised: 12/23/2018] [Accepted: 01/09/2019] [Indexed: 10/27/2022]
Abstract
OBJECTIVE To investigate the median effective dose 50 (ED50) of midazolam required for endotracheal intubation when used for co-induction of anesthesia with a low dose of alfaxalone in sedated cats. STUDY DESIGN Randomized up-and-down study. ANIMALS A group of 14 mixed-breed cats (eight males, six females), aged 5-12 years and weighing 4.4-6.8 kg. METHODS The cats were randomly assigned in a sequential allocation numbers from one to 14. Cats were sedated with dexmedetomidine (3 μg kg-1) and methadone (0.3 mg kg-1) intramuscularly. After 15 minutes, the quality of sedation was subjectively evaluated. Anesthesia induction was performed by intravenous (IV) administration of alfaxalone (0.25 mg kg-1) over a 60 second interval, followed by another 60 second interval, and then an IV dose of midazolam was administered over a 5 second interval. The initial midazolam dose was 0.3 mg kg-1; then, the midazolam dose was adjusted by ±0.1 mg kg-1 for each consecutive cat based on successful or unsuccessful endotracheal intubation of the previous animal following an up-and-down method. This sequence was followed until six nonsequential crossovers were observed. Crossover was defined as two opposite outcomes in two sequential animals. Data were analyzed using isotonic regression with bootstrapping for determination of midazolam ED50 and logistic regression for correlations (p < 0.05). RESULTS Overall, six independent crossovers were found, and ED50 of midazolam was 0.08 ± 0.04 mg kg-1. Sedation score and successful tracheal intubation had a strong positive correlation (p = 0.02). CONCLUSIONS AND CLINICAL RELEVANCE This study determined that 0.08 ± 0.04 mg kg-1 of midazolam co-administered with 0.25 mg kg-1 of alfaxalone IV allowed smooth endotracheal intubation in half of the cats sedated with methadone and dexmedetomidine at the doses used in this study.
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Affiliation(s)
- Angie Lagos-Carvajal
- Department of Veterinary Clinical Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, LA, USA
| | - Patricia Queiroz-Williams
- Department of Veterinary Clinical Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, LA, USA.
| | - Anderson da Cunha
- Department of Veterinary Clinical Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, LA, USA
| | - Chin-Chi Liu
- Department of Veterinary Clinical Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, LA, USA
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Kropf J, Hughes JML. Effects of midazolam on cardiovascular responses and isoflurane requirement during elective ovariohysterectomy in dogs. Ir Vet J 2018; 71:26. [PMID: 30568789 PMCID: PMC6297997 DOI: 10.1186/s13620-018-0136-y] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2018] [Accepted: 12/03/2018] [Indexed: 11/25/2022] Open
Abstract
Background A prospective, randomized, placebo-controlled, blinded clinical study was conducted to determine whether a single dose of midazolam affects the cardiovascular response to surgical manipulation of the ovaries during elective ovariohysterectomy. Thirty-nine client-owned dogs undergoing elective ovariohysterectomy were recruited. After scoring cage demeanour, dogs were premedicated with acepromazine (0.03 mg kg-1) and pethidine (3 mg kg-1) intramuscularly into the quadriceps muscle and 20 min later sedation was scored. Anaesthesia was induced with propofol intravenously (IV) to effect. The study treatment (group M: midazolam (0.25 mg kg-1); or group P: placebo (Hartmann’s solution) (0.125 ml kg-1)) was administered IV before the intra-operative manipulation of the first ovary. Anaesthesia was maintained with isoflurane in oxygen. Morphine (0.3 mg kg-1 IV) was administered prior to the start of surgery. The vaporizer setting was adjusted according to the depth of anaesthesia. If an end-tidal isoflurane concentration (FE’Iso) above 1.6% was required additional analgesia was provided with fentanyl (2 μg kg-1). Dogs received meloxicam (0.2 mg kg-1 IV) at the end of procedure. Heart rate, mean arterial blood pressure, respiratory rate and end-tidal partial pressure of carbon dioxide as well as FE’Iso were recorded and analysed. Results A statistical significant difference between groups was detected in FE’Iso, with group M requiring a significantly lower FE’Iso than group P (14.3%) after administration of midazolam. No differences between groups was shown for percentage change in heart rate and mean arterial blood pressure, or end-tidal carbon dioxide and requirement for mechanical ventilation, or rescue analgesia. There was no statistically significant difference in the incidence of complications in group M and P. Group M received significantly more succinylated gelatin solution pre-administration of midazolam than group P, but no differences in fluid administration post-administration of the study treatment (midazolam/placebo) were detected. No statistical significant difference was demonstrated for the use of anticholinergic agents, dobutamine or noradrenaline. Conclusion No significant effect on cardiovascular parameters could be observed with administration of midazolam, but a modest (14.3%) isoflurane-sparing effect was detected.
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Affiliation(s)
- Josephine Kropf
- 1Anaesthesia Department, Small Animal Hospital, School of Veterinary Medicine, University of Glasgow, 464 Bearsden Road, Glasgow, G61 1QH UK
| | - J M Lynne Hughes
- 2Veterinary Anaesthesia, UCD Veterinary Hospital, UCD School of Veterinary Medicine, University College Dublin, DO4 W6F6 Dublin, Ireland
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Reed R, Doherty T. Minimum alveolar concentration: Key concepts and a review of its pharmacological reduction in dogs. Part 1. Res Vet Sci 2018; 117:266-270. [PMID: 29331922 DOI: 10.1016/j.rvsc.2018.01.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2017] [Revised: 11/25/2017] [Accepted: 01/08/2018] [Indexed: 11/25/2022]
Abstract
OBJECTIVE To outline the major components of the minimum alveolar concentration (MAC) and review the literature in regard to pharmacological manipulation of the MAC of halothane, isoflurane, sevoflurane, enflurane, and desflurane in dogs. The pharmacologic agents included are alpha-2 agonists, benzodiazepines, propofol, maropitant, opioids, lidocaine, acepromazine, non-steroidal anti-inflammatory agents, and NMDA antagonists. Part 1 will focus on summarizing the relevance, measurement, and mechanisms of MAC and review the effects of alpha-2 agonists, benzodiazepines, and propofol on MAC. DATABASES USED PubMed, Google Scholar, CAB Abstracts. Search terms used: minimum alveolar concentration, MAC, dog, canine, inhaled anesthetic potency, isoflurane, sevoflurane, desflurane, enflurane, and halothane. CONCLUSIONS Many drugs reduce the MAC of inhaled anesthetics in dogs, and allow for a clinically important decrease in inhalant anesthetic use. A decrease in MAC may decrease the adverse cardiovascular and pulmonary effects associated with the use of high concentrations of inhaled anesthetics.
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Affiliation(s)
- Rachel Reed
- University of Georgia College of Veterinary Medicine, 2200 College Station Rd., Athens, GA 30605, USA.
| | - Thomas Doherty
- University of Tennessee College of Veterinary Medicine, 2407 River Dr., Knoxville, TN 37996, USA.
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Regalin D, Gehrcke MI, Comassetto F, Regalin B, Rosa L, Padilha V, Lima I, Moraes A, Oleskovicz N. Avaliação metabólica e hemodinâmica de dois protocolos de sedação prolongada em cães. ARQ BRAS MED VET ZOO 2017. [DOI: 10.1590/1678-4162-9304] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
RESUMO Objetivou-se determinar a viabilidade de dois protocolos de sedação para ventilação prolongada em cães e seus efeitos hemodinâmicos e metabólicos. Doze cães, alocados aleatoriamente em dois grupos (n=6), receberam infusão contínua de midazolam (0,5mg/kg/h), fentanil (10µg/kg/h) e propofol (18mg/kg/h) no GMF ou cetamina (0,6mg/kg/h), morfina (0,26mg/kg/h) e propofol (18mg/kg/h) no GCM, durante 24 horas. Os cães foram ventilados mecanicamente com FiO2 de 40%, mantendo-se a normocapnia. A FC diminuiu 32% no GMF e 34% no GCM ao longo do tempo, reduzindo o IC em 24% no GMF e em 29% no GCM. A CaO2, o CvmO2, a DO2 e o VO2 diminuíram no GCM (5%, 16%, 31% e 7%) e no GMF (4%, 19%, 26% e 15%), respectivamente. A TEO2 aumentou 32% no GMF e 36% no GCM, sem diferenças entre grupos, porém a calorimetria indireta demonstrou diminuição do VO2, minimizando a redução da DO2. Não houve diferença entre os tempos para extubação, deambulação e recuperação total, com médias globais (minutos) de 33,8±15,9, 134,8±60,7 e 208±77,5, respectivamente. Conclui-se que ambos os protocolos permitiram a ventilação mecânica, com redução do IC e da DO2, porém sem prejuízos hemodinâmicos e metabólicos, podendo ser utilizados com segurança em cães hígidos.
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Affiliation(s)
| | | | | | | | - L. Rosa
- Universidade do Estado de Santa Catarina, Brazil
| | | | - I.T. Lima
- Universidade do Estado de Santa Catarina, Brazil
| | - A.N. Moraes
- Universidade do Estado de Santa Catarina, Brazil
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Adrian D, Papich M, Baynes R, Murrell J, Lascelles BDX. Chronic maladaptive pain in cats: A review of current and future drug treatment options. Vet J 2017; 230:52-61. [PMID: 28887012 DOI: 10.1016/j.tvjl.2017.08.006] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2017] [Revised: 08/10/2017] [Accepted: 08/17/2017] [Indexed: 11/28/2022]
Abstract
Despite our increasing understanding of the pathophysiology underlying chronic or maladaptive pain, there is a significant gap in our ability to diagnose and treat the condition in domestic cats. Newer techniques being used to identify abnormalities in pain processing in the cat include validated owner questionnaires, measurement of movement and activity, and measurement of sensory thresholds and somatomotor responses. While some data are available evaluating possible therapeutics for the treatment of chronic pain in the cat, most data are limited to normal cats. This review details our current understanding of chronic or maladaptive pain, techniques for the detection and measurement of the condition and the associated central nervous changes, as well as an overview of the data evaluating potential therapeutics in cats.
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Affiliation(s)
- Derek Adrian
- Comparative Pain Research and Education Centre, Department of Clinical Sciences, College of Veterinary Medicine, North Carolina State University, Raleigh, NC, USA
| | - Mark Papich
- Molecular and Biomedical Sciences, College of Veterinary Medicine, North Carolina State University, Raleigh, NC, USA
| | - Ron Baynes
- Population Health and Pathobiology, College of Veterinary Medicine, North Carolina State University, Raleigh, NC, USA
| | - Jo Murrell
- School of Veterinary Sciences, University of Bristol, Bristol, UK
| | - B Duncan X Lascelles
- Comparative Pain Research and Education Centre, Department of Clinical Sciences, College of Veterinary Medicine, North Carolina State University, Raleigh, NC, USA; Center for Pain Research and Innovation, UNC School of Dentistry, Chapel Hill, NC, USA; Center for Translational Pain Research, Department of Anesthesiology, Duke University, Durham, NC, USA.
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Johnson AN, Seddighi R, Rohrbach BW, Cox SK, Egger CM, Martin-Flores M, Doherty TJ. Effects of magnesium sulfate and propofol on the minimum alveolar concentration preventing motor movement in sevoflurane-anesthetized dogs. Am J Vet Res 2016; 77:575-81. [PMID: 27227494 DOI: 10.2460/ajvr.77.6.575] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
OBJECTIVE To evaluate the effect of MgSO4, alone and in combination with propofol, on the minimum alveolar concentration preventing motor movement (MACNM) in sevoflurane-anesthetized dogs. ANIMALS 6 healthy purpose-bred adult male Beagles (least squares mean ± SEM body weight, 12.0 ± 1.1 kg). PROCEDURES Dogs were anesthetized 3 times at weekly intervals. The MACNM was measured 45 minutes after induction of anesthesia (baseline; MACNM-B) and was determined each time by use of a noxious electrical stimulus. Treatments were administered as a loading dose and constant rate infusion (CRI) as follows: treatment 1, MgSO4 loading dose of 45 mg/kg and CRI of 15 mg/kg/h; treatment 2, propofol loading dose of 4 mg/kg and CRI of 9 mg/kg/h; and treatment 3, MgSO4 and propofol combination (same doses used previously for each drug). A mixed-model ANOVA and Tukey-Kramer tests were used to determine effects of each treatment on the percentage decrease from MACNM-B. Data were reported as least squares mean ± SEM values. RESULTS Decrease from MACNM-B was 3.4 ± 3.1%, 48.3 ± 3.1%, and 50.3 ± 3.1%, for treatments 1, 2, and 3, respectively. The decrease for treatments 2 and 3 was significantly different from that for treatment 1; however, no significant difference existed between results for treatments 2 and 3. CONCLUSIONS AND CLINICAL RELEVANCE MgSO4 did not affect MACNM, nor did it potentiate the effects of propofol on MACNM. Administration of MgSO4 in this study appeared to provide no clinical advantage as an anesthetic adjuvant.
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Schütter AF, Tünsmeyer J, Kästner SBR. Influence of metamizole on 1) minimal alveolar concentration of sevoflurane in dogs and 2) on thermal and mechanical nociception in conscious dogs. Vet Anaesth Analg 2016; 43:215-26. [DOI: 10.1111/vaa.12289] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2014] [Accepted: 03/25/2015] [Indexed: 01/15/2023]
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Figueiró MR, Soares JH, Ascoli FO, Werre S, Gómez de Segura IÁ. Isoflurane MAC determination in dogs using three intensities of constant-current electrical stimulation. Vet Anaesth Analg 2016; 43:464-71. [PMID: 27531057 DOI: 10.1111/vaa.12341] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2015] [Accepted: 11/13/2015] [Indexed: 11/30/2022]
Abstract
OBJECTIVES To compare isoflurane minimum alveolar concentrations (MACs) in dogs determined using three intensities of constant-current electrical stimulation applied at the tail, and thoracic and pelvic limbs, and to compare isoflurane MACs obtained with all combinations of electrical stimulation and anatomic site with those obtained using the tail clamp as the noxious stimulus. STUDY DESIGN Randomized trial. ANIMALS Six mixed-breed, adult female dogs aged 1-2 years and weighing 11.1 ± 4.4 kg. METHODS In each dog, MAC was determined by the bracketing method with the tail clamp (MACTAILCLAMP ), and three electrical currents (10 mA, 30 mA, 50 mA) at three anatomic sites (thoracic limb, pelvic limb, tail). Each MAC achieved with electrical stimulation was compared with MACTAILCLAMP using a mixed-model anova and Dunnett's procedure for multiple comparisons. The effects of current intensity and anatomic site on isoflurane MAC were tested using a mixed-model anova followed by Tukey's test for multiple comparisons (p < 0.05). RESULTS Mean MACTAILCLAMP was 1.69%. MACs achieved with currents of 30 mA and 50 mA did not differ independently of anatomic site. When currents of 10 mA were applied to the tail and thoracic limb, resulting MACs were lower than those obtained using currents of 30 mA and 50 mA. Currents of 30 mA and 50 mA provided MACs that did not differ from those of MACTAILCLAMP , whereas a current of 10 mA achieved the same result only for the pelvic limb. CONCLUSIONS AND CLINICAL RELEVANCE Isoflurane MAC is affected by current intensity and anatomic site. Current intensities of 30 mA and 50 mA provided consistent results when applied to the tail, and thoracic and pelvic limbs that did not differ from those obtained using the tail clamp. Consequently, they can be used in place of the tail clamp in MAC studies in dogs.
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Affiliation(s)
- Marivaldo R Figueiró
- Veterinary Surgery and Clinics Graduation Program, Veterinary College, Fluminense Federal University, Niterói, Brazil
| | - Joao Hn Soares
- Veterinary Surgery and Clinics Graduation Program, Veterinary College, Fluminense Federal University, Niterói, Brazil.,Department of Small Animal Clinical Sciences, Virginia-Maryland Regional College of Veterinary Medicine, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA
| | - Fabio O Ascoli
- Veterinary Surgery and Clinics Graduation Program, Veterinary College, Fluminense Federal University, Niterói, Brazil
| | - Stephen Werre
- Laboratory for Study Design and Statistical Analysis, Virginia-Maryland Regional College of Veterinary Medicine, Polytechnic Institute and State University, Blacksburg, VA, USA
| | - Ignacio Á Gómez de Segura
- Department of Animal Medicine and Surgery, Faculty of Veterinary Medicine, University Complutense, Madrid, Spain
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Drees R, Johnson RA, Stepien RL, Munoz Del Rio A, Saunders JH, François CJ. QUANTITATIVE PLANAR AND VOLUMETRIC CARDIAC MEASUREMENTS USING 64 MDCT AND 3T MRI VS. STANDARD 2D AND M-MODE ECHOCARDIOGRAPHY: DOES ANESTHETIC PROTOCOL MATTER? Vet Radiol Ultrasound 2015; 56:638-57. [PMID: 26082285 DOI: 10.1111/vru.12269] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2014] [Accepted: 04/28/2015] [Indexed: 12/17/2022] Open
Abstract
Cross-sectional imaging of the heart utilizing computed tomography and magnetic resonance imaging (MRI) has been shown to be superior for the evaluation of cardiac morphology and systolic function in humans compared to echocardiography. The purpose of this prospective study was to test the effects of two different anesthetic protocols on cardiac measurements in 10 healthy beagle dogs using 64-multidetector row computed tomographic angiography (64-MDCTA), 3T magnetic resonance (MRI) and standard awake echocardiography. Both anesthetic protocols used propofol for induction and isoflourane for anesthetic maintenance. In addition, protocol A used midazolam/fentanyl and protocol B used dexmedetomedine as premedication and constant rate infusion during the procedure. Significant elevations in systolic and mean blood pressure were present when using protocol B. There was overall good agreement between the variables of cardiac size and systolic function generated from the MDCTA and MRI exams and no significant difference was found when comparing the variables acquired using either anesthetic protocol within each modality. Systolic function variables generated using 64-MDCTA and 3T MRI were only able to predict the left ventricular end diastolic volume as measured during awake echocardiogram when using protocol B and 64-MDCTA. For all other systolic function variables, prediction of awake echocardiographic results was not possible (P = 1). Planar variables acquired using MDCTA or MRI did not allow prediction of the corresponding measurements generated using echocardiography in the awake patients (P = 1). Future studies are needed to validate this approach in a more varied population and clinically affected dogs.
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Affiliation(s)
| | | | | | | | - Jimmy H Saunders
- Faculty of Veterinary Medicine, UGent, Salisburylaan 133, 9820, Merelbeke, Belgium
| | - Christopher J François
- Department of Radiology, School of Medicine and Public Health, UW-Madison, 600 Highland Avenue, Madison, WI, 53792
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Drees R, Johnson RA, Stepien RL, Munoz Del Rio A, François CJ. Effects of two different anesthetic protocols on cardiac flow measured by two dimensional phase contrast magnetic resonance imaging. Vet Radiol Ultrasound 2015; 56:168-75. [PMID: 25124271 PMCID: PMC4329287 DOI: 10.1111/vru.12200] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2013] [Accepted: 05/04/2014] [Indexed: 01/01/2023] Open
Abstract
Companion animals are routinely anesthetized or heavily sedated for cardiac MRI studies, however effects of varying anesthetic protocols on cardiac function measurements are incompletely understood. The purpose of this prospective study was to compare effects of two anesthetic protocols (Protocol A: Midazolam, fentanyl; Protocol B: Dexmedetomidine) on quantitative and qualitative blood flow values measured through the aortic, pulmonic, mitral, and tricuspid valves using two-dimensional phase contrast magnetic resonance imaging (2D PC MRI) in healthy dogs. Mean flow per heartbeat values through the pulmonary artery (Qp) and aorta (Qs) were compared to right and left ventricular stroke volumes (RVSV, LVSV) measured using a reference standard of 2D Cine balanced steady-state free precession MRI. Pulmonary to systemic flow ratio (Qp/Qs) was also calculated. Differences in flow and Qp/Qs values generated using 2D PC MRI did not differ between the two anesthetic protocols (P = 1). Mean differences between Qp and RVSV were 3.82 ml/beat (95% limits of agreement: 3.62, -11.26) and 1.9 ml/beat (-7.86, 11.66) for anesthesia protocols A and B, respectively. Mean differences between Qs and LVSV were 1.65 ml/beat (-5.04, 8.34) and 0.03 ml/beat (-4.65, 4.72) for anesthesia protocols A and B, respectively. Mild tricuspid or mitral reflux was seen in 2/10 dogs using 2D PC MRI. No aortic or pulmonic insufficiency was observed. Findings from the current study indicated that these two anesthetic protocols yield similar functional measures of cardiac blood flow using 2D PC MRI in healthy dogs. Future studies in clinically affected patients are needed.
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Affiliation(s)
- Randi Drees
- VMTH DSS, UW-Madison, Madison, WI, 53726, USA
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Kleine SA, Quandt JE, Hofmeister EH, Peroni J. The effect of midazolam on the recovery quality, recovery time and the minimum alveolar concentration for extubation in the isoflurane-anesthetized pig. Lab Anim 2014; 49:111-6. [PMID: 25378139 DOI: 10.1177/0023677214556668] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
There are no reported studies evaluating the effect of midazolam on recovery quality, recovery time or minimum alveolar concentration (MAC) at which extubation occurs (MAC extubation). Our hypotheses were that midazolam administered prior to recovery would decrease MAC extubation, prolong recovery time but provide a smoother recovery. Sixteen Yorkshire pigs were anesthetized with isoflurane for approximately 5 h. The end-tidal isoflurane concentration was then stabilized at 1.4% for 20 min. Pigs were randomly assigned to receive midazolam or saline. The vaporizer was decreased by 10% every 10 min until extubation. Pigs were declared awake by a blinded observer and were assigned a recovery score by the same observer. Mean MAC extubation was not significantly different for pigs receiving saline prior to recovery compared with those pigs receiving midazolam. The overall mean MAC extubation for both groups was 0.6 ± 0.4 vol%. Time to extubation was not significantly longer with midazolam (124 ± 36 min) compared with the saline group (96 ± 61 min; P = 0.09). Recovery score was not significantly different between groups (midazolam, 0.86 ± 1.1; saline 0.5 ± 0.5; P = 0.26). In conclusion, midazolam did not affect MAC extubation. There was no advantage of administering midazolam in the recovery period when performing step-down titration of isoflurane anesthesia.
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Affiliation(s)
- S A Kleine
- Department of Small Animal Medicine and Surgery
| | - J E Quandt
- Department of Small Animal Medicine and Surgery
| | | | - J Peroni
- Department of Large Animal Medicine, College of Veterinary Medicine, University of Georgia, Athens, GA, USA
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Drees R, Johnson RA, Pinkerton M, Del Rio AM, Saunders JH, François CJ. Effects of two different anesthetic protocols on 64-MDCT coronary angiography in dogs. Vet Radiol Ultrasound 2014; 56:46-54. [PMID: 25065815 DOI: 10.1111/vru.12185] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2013] [Accepted: 04/24/2014] [Indexed: 11/26/2022] Open
Abstract
Heart rate is a major factor influencing diagnostic image quality in computed tomographic coronary artery angiography (MDCT-CA), with an ideal heart rate of 60-65 beats/min in humans. The purpose of this prospective study was to compare effects of two different clinically applicable anesthetic protocols on cardiovascular parameters and 64-MDCT-CA quality in 10 healthy dogs. Scan protocols and bolus volumes were standardized. Image evaluations were performed in random order by a board-certified veterinary radiologist who was unaware of anesthetic protocols used. Heart rate during image acquisition did not differ between protocols (P = 1), with 80.6 ± 7.5 bpm for protocol A and 79.2 ± 14.2 bpm for protocol B. Mean blood pressure was significantly higher (P > 0.05) using protocol B (protocol A 62.9 ± 9.1 vs. protocol B 72.4 ± 15.9 mmHg). The R-R intervals allowing for best depiction of individual coronary artery segments were found in the end diastolic period and varied between the 70% and 95% interval. Diagnostic quality was rated excellent, good, and moderate in the majority of the segments evaluated, with higher scores given for more proximal segments and lower for more distal segments, respectively. Blur was the most commonly observed artifact and mainly affected the distal segments. No significant differences were identified between the two protocols for optimal reconstruction interval, diagnostic quality and measured length individual segments, or proximal diameter of the coronary arteries (P = 1). Findings indicated that, when used with a standardized bolus volume, both of these anesthetic protocols yielded diagnostic quality coronary 64-MDCT-CA exams in healthy dogs.
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Affiliation(s)
- Randi Drees
- Department of Surgical Sciences, UW-Madison VMTH, 2015 Linden Drive, Madison, WI 53706
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Gozalo-Marcilla M, Hopster K, Gasthuys F, Krajewski AE, Schwarz A, Schauvliege S. Minimum end-tidal sevoflurane concentration necessary to prevent movement during a constant rate infusion of morphine, or morphine plus dexmedetomidine in ponies. Vet Anaesth Analg 2014; 41:212-9. [DOI: 10.1111/vaa.12090] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2012] [Accepted: 03/25/2013] [Indexed: 12/01/2022]
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Shaughnessy MR, Hofmeister EH. A systematic review of sevoflurane and isoflurane minimum alveolar concentration in domestic cats. Vet Anaesth Analg 2014; 41:1-13. [DOI: 10.1111/vaa.12083] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2012] [Accepted: 03/13/2013] [Indexed: 10/26/2022]
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Robinson R, Borer–Weir K. A dose titration study into the effects of diazepam or midazolam on the propofol dose requirements for induction of general anaesthesia in client owned dogs, premedicated with methadone and acepromazine. Vet Anaesth Analg 2013; 40:455-63. [DOI: 10.1111/vaa.12052] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2012] [Accepted: 01/23/2013] [Indexed: 01/07/2023]
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Reilly S, Seddighi R, Egger CM, Rohrbach BW, Doherty TJ, Qu W, Johnson JR. The effect of fentanyl on the end-tidal sevoflurane concentration needed to prevent motor movement in dogs. Vet Anaesth Analg 2013; 40:290-6. [PMID: 23368842 DOI: 10.1111/vaa.12013] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2011] [Accepted: 02/03/2012] [Indexed: 11/26/2022]
Abstract
OBJECTIVE The objectives of this study were to determine the effects of fentanyl on the end-tidal concentration of sevoflurane needed to prevent motor movement (MACNM ) in response to noxious stimulation, and to evaluate if acute tolerance develops. STUDY DESIGN Randomized cross-over experimental study. ANIMALS Six healthy, adult (2-3 years old), intact male, mixed-breed dogs weighing 16.2 ± 1.1 kg. METHODS Six dogs were randomly assigned to receive one of three separate treatments over a 3 week period. After baseline sevoflurane MACNM (MACNM-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 MACNM was defined as the minimum end-tidal sevoflurane concentration preventing motor movement. The first post-treatment MACNM (MACNM-I) determination was initiated 90 minutes after the start of the CRI, and a second MACNM (MACNM - II) determination was initiated 3 hours after MACNM-I was established. RESULTS The overall least square mean MACNM-B for all groups was 2.66%. All treatments decreased (p < 0.05) MACNM, 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. MACNM-I was not significantly different from MACNM-II within treatments. CONCLUSIONS AND CLINICAL RELEVANCE Fentanyl doses in the range of 3-12 μg kg(-1) hour(-1) significantly decreased the sevoflurane MACNM. Clinically significant tolerance to fentanyl did not occur under the study conditions.
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Affiliation(s)
- Sabrina Reilly
- Department of Small Animal Clinical Sciences, College of Veterinary Medicine, University of Tennessee, Knoxville, TN 37996, USA
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Martin-Flores M. Neuromuscular blocking agents and monitoring in the equine patient. Vet Clin North Am Equine Pract 2013; 29:131-54. [PMID: 23498049 DOI: 10.1016/j.cveq.2012.11.010] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022] Open
Abstract
This article briefly reviews the physiology of the neuromuscular junction and the pharmacologic mechanisms of neuromuscular blocking agents. The clinical use of modern agents is discussed. Monitoring techniques used to assess the level of neuromuscular block and to exclude residual paralysis at the end of an anesthetic procedure are reviewed.
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Affiliation(s)
- Manuel Martin-Flores
- Department of Clinical Sciences, College of Veterinary Medicine, Cornell University, Box 32, Ithaca, NY 14853, USA.
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Seddighi R, Egger CM, Rohrbach BW, Hobbs M, Doherty TJ. Effect of nitrous oxide on the minimum alveolar concentration for sevoflurane and the minimum alveolar concentration derivatives that prevent motor movement and autonomic responses in dogs. Am J Vet Res 2012; 73:341-5. [DOI: 10.2460/ajvr.73.3.341] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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