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Machado ML, Soares JHN, Pypendop BH, Henao-Guerrero N, Oliveira RLS. Effect of fentanyl, with or without treatment of bradycardia, on the minimum alveolar concentration of isoflurane and cardiovascular function in dogs. Vet Anaesth Analg 2021; 49:26-35. [PMID: 34654643 DOI: 10.1016/j.vaa.2021.09.001] [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: 05/17/2021] [Revised: 09/08/2021] [Accepted: 09/10/2021] [Indexed: 11/27/2022]
Abstract
OBJECTIVE To determine the effect of fentanyl on the minimum alveolar concentration of isoflurane (MACISO) and cardiovascular variables in dogs, and how the treatment of bradycardia affects them. STUDY DESIGN Prospective, randomized crossover-controlled trial. ANIMALS A total of six male Beagle dogs weighing 9.9 ± 0.7 kg (mean ± standard deviation) and aged 13 months. METHODS To each dog, two treatments were assigned on different days: fentanyl (FENTA) or fentanyl plus glycopyrrolate (FENTAglyco) to maintain heart rate (HR) between 100 and 132 beats minute-1. Determinations of MACISO were performed with 10 plasma fentanyl target concentrations ([Fenta]Target (0, 0.16, 0.32, 0.64, 1.25, 2.5, 5.0, 10.0, 20.0 and 40.0 ng mL-1) for FENTA and 5 [Fenta]Target (0, 1.25, 2.5, 5.0, 10.0 ng mL-1)) for FENTAglyco. During each MACISO determination, cardiovascular variables [mean arterial pressure (MAP), HR and cardiac index (CI)] were measured, and systemic vascular resistance index (SVRI) calculated. Pharmacodynamic models were used to describe the plasma fentanyl concentration [Fenta]-response relationship for the effect on MACISO and cardiovascular variables. A mixed-model analysis of variance followed by Dunnett's or Tukey's test, and the Bonferroni adjustment were used for comparisons within and between each treatment, respectively. Significance was set as p < 0.05. RESULTS Fentanyl decreased MACISO by a maximum of 84%. The [Fenta] producing 50% decrease in MAC, HR and CI were 2.64, 3.65 and 4.30 ng mL-1 (typical values of population model), respectively. The prevention of fentanyl-mediated bradycardia caused no significant effect on MACISO, but increased HR, MAP and CI, and decreased SVRI when compared with isoflurane alone. CONCLUSIONS AND CLINICAL RELEVANCE Fentanyl caused a plasma concentration-dependent decrease in MACISO, HR and CI and an increase in SVRI. Cardiovascular improvements associated with fentanyl in isoflurane-anesthetized dogs only occurred when the fentanyl-mediated bradycardia was prevented.
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Affiliation(s)
- Marcela L Machado
- Department of Small Animal Clinical Sciences, Virginia-Maryland College of Veterinary Medicine, Virginia Tech, Blacksburg, VA, USA
| | - Joao H N Soares
- Department of Small Animal Clinical Sciences, Virginia-Maryland College of Veterinary Medicine, Virginia Tech, Blacksburg, VA, USA; Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California Davis, Davis, CA, USA.
| | - Bruno H Pypendop
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California Davis, Davis, CA, USA
| | - Natalia Henao-Guerrero
- Department of Small Animal Clinical Sciences, Virginia-Maryland College of Veterinary Medicine, Virginia Tech, Blacksburg, VA, USA
| | - Renato L S Oliveira
- Department of Small Animal Clinical Sciences, Virginia-Maryland College of Veterinary Medicine, Virginia Tech, Blacksburg, VA, USA
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Akashi N, Murahata Y, Hosokawa M, Hikasa Y, Okamoto Y, Imagawa T. Cardiovascular and renal effects of constant rate infusions of remifentanil, dexmedetomidine and their combination in dogs anesthetized with sevoflurane. J Vet Med Sci 2020; 83:285-296. [PMID: 33310997 PMCID: PMC7972892 DOI: 10.1292/jvms.20-0457] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
We evaluated changes in cardiovascular and renal functions as well as arginine vasopressin (AVP) secretion, with remifentanil and dexmedetomidine administration alone or in combination in sevoflurane-anesthetized dogs. Six healthy adult Beagle dogs received one of the following four treatments in a randomized crossover study: saline (C), remifentanil alone at successively increasing doses (R; 0.15, 0.60, and 2.40 µg/kg/min), dexmedetomidine alone (D; 0.5 µg/kg intravenously for initial 10 min followed by a constant rate infusion at 0.5 µg/kg/hr), and a combination of remifentanil and dexmedetomidine at the above-mentioned doses (RD). Sevoflurane doses were adjusted to 1.5 times of minimum alveolar concentration (MAC) equivalent according to MAC-sparing effects with remifentanil and dexmedetomidine as previously reported. Cardiovascular measurements, renal function data, and plasma AVP concentrations were determined before and every 60 min until 180 min after drug administration as per each treatment. In the R, D and RD, heart rate significantly decreased and mean arterial pressure significantly increased from baseline or with C. Cardiac index significantly decreased and systemic vascular resistance index increased with D and RD. Oxygen extraction ratio, renal blood flow, and glomerular filtration rate were not affected. The plasma AVP concentrations significantly decreased in D and RD, but increased in R. Only in D, the natriuresis was elicited. The combination of remifentanil and dexmedetomidine in sevoflurane-anesthetized dogs was acceptable in terms of the hemodynamics, oxygenation, and renal function. Remifentanil may interfere with dexmedetomidine-induced diuresis and inhibition of AVP secretion.
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Affiliation(s)
- Natsuki Akashi
- Joint Department of Veterinary Medicine, Faculty of Agriculture, Tottori University, 4-101 Koyama-Minami, Tottori, Tottori 680-8553, Japan
| | - Yusuke Murahata
- Joint Department of Veterinary Medicine, Faculty of Agriculture, Tottori University, 4-101 Koyama-Minami, Tottori, Tottori 680-8553, Japan
| | - Masahumi Hosokawa
- Joint Department of Veterinary Medicine, Faculty of Agriculture, Tottori University, 4-101 Koyama-Minami, Tottori, Tottori 680-8553, Japan
| | - Yoshiaki Hikasa
- Joint Department of Veterinary Medicine, Faculty of Agriculture, Tottori University, 4-101 Koyama-Minami, Tottori, Tottori 680-8553, Japan
| | - Yoshiharu Okamoto
- Joint Department of Veterinary Medicine, Faculty of Agriculture, Tottori University, 4-101 Koyama-Minami, Tottori, Tottori 680-8553, Japan
| | - Tomohiro Imagawa
- Joint Department of Veterinary Medicine, Faculty of Agriculture, Tottori University, 4-101 Koyama-Minami, Tottori, Tottori 680-8553, Japan
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Vézina-Audette R, Steagall PVM, Gianotti G. Prevalence of and covariates associated with the oculocardiac reflex occurring in dogs during enucleation. J Am Vet Med Assoc 2020; 255:454-458. [PMID: 31355722 DOI: 10.2460/javma.255.4.454] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
OBJECTIVE To determine the prevalence of and covariates associated with the oculocardiac reflex (OCR) occurring in dogs during enucleations. SAMPLE 145 dogs that underwent enucleation at 2 veterinary teaching hospitals between January 2010 and June 2015. PROCEDURES Information was collected from the medical records of included dogs regarding age and body weight at hospital admission, breed (for classification of brachycephalic status), and whether they had received anticholinergic drugs or a retrobulbar nerve block (RNB) prior to enucleation. An OCR was considered to have occurred if there was a sudden decrease of ≥ 30% in heart rate from the baseline value (mean heart rate prior to the sudden decrease) during surgery in the absence of intraoperative administration of opioids or α2-adrenoceptor agonists. Associations were explored between the collected data and the prevalence of OCR by means of binomial logistic regression. RESULTS 4.8% (7/145) of dogs had an OCR noted during enucleation. Dogs that received a preoperative RNB (n = 82) had significantly lower odds of an OCR being observed than dogs that received no preoperative RNB (OR, 0.12). No association with OCR was identified for age or brachycephalic conformation or for preoperative administration of anticholinergic drugs. CONCLUSIONS AND CLINICAL RELEVANCE These findings suggested that preoperative administration of an RNB, but not preoperative administration of anticholinergic drugs, was associated with a lower prevalence of OCR in dogs during enucleations.
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Akashi N, Murahata Y, Kishida H, Hikasa Y, Azuma K, Imagawa T. Effects of constant rate infusions of dexmedetomidine, remifentanil and their combination on minimum alveolar concentration of sevoflurane in dogs. Vet Anaesth Analg 2020; 47:490-498. [PMID: 32471632 DOI: 10.1016/j.vaa.2020.04.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2019] [Revised: 04/02/2020] [Accepted: 04/03/2020] [Indexed: 12/12/2022]
Abstract
OBJECTIVE To evaluate the effects of constant rate infusions (CRIs) of dexmedetomidine and remifentanil alone and their combination on minimum alveolar concentration (MAC) of sevoflurane in dogs. STUDY DESIGN Randomized crossover experimental study. ANIMALS A total of six (three males, three females) healthy, adult neutered Beagle dogs weighing 12.6 ± 1.4 kg. METHODS Anesthesia was induced with sevoflurane in oxygen until endotracheal intubation was possible and anesthesia maintained with sevoflurane using positive-pressure ventilation. Each dog was anesthetized five times and was administered each of the following treatments: saline (1 mL kg-1 hour-1) or dexmedetomidine at 0.1, 0.5, 1.0 or 5.0 μg kg-1 loading dose intravenously over 10 minutes followed by CRI at 0.1, 0.5, 1.0 or 5.0 μg kg-1 hour-1, respectively. Following 60 minutes of CRI, sevoflurane MAC was determined in duplicate using an electrical stimulus (50 V, 50 Hz, 10 ms). Then, CRI of successively increasing doses of remifentanil (0.15, 0.60 and 2.40 μg kg-1 minute-1) was added to each treatment. MAC was also determined after 30 minutes equilibration at each remifentanil dose. Isobolographic analysis determined interaction from the predicted doses required for a 50% MAC reduction (ED50) with remifentanil, dexmedetomidine and remifentanil combined with dexmedetomidine, with the exception of dexmedetomidine 5.0 μg kg-1 hour-1, obtained using log-linear regression analysis. RESULTS The sevoflurane MAC decreased dose-dependently with increasing infusion rates of dexmedetomidine and remifentanil. Remifentanil ED50 values were lower when combined with dexmedetomidine than those obtained during saline-remifentanil. Synergistic interactions between dexmedetomidine and remifentanil for MAC reduction occurred with dexmedetomidine at 0.5 and 1.0 μg kg-1 hour-1. CONCLUSIONS AND CLINICAL RELEVANCE Combined CRIs of dexmedetomidine and remifentanil synergistically resulted in sevoflurane MAC reduction. The combination of dexmedetomidine and remifentanil effectively reduced the requirement of sevoflurane during anesthesia in dogs.
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Affiliation(s)
- Natsuki Akashi
- Joint Department of Veterinary Medicine, Faculty of Agriculture, Tottori University, Tottori, Japan
| | - Yusuke Murahata
- Joint Department of Veterinary Medicine, Faculty of Agriculture, Tottori University, Tottori, Japan.
| | - Hikaru Kishida
- Joint Department of Veterinary Medicine, Faculty of Agriculture, Tottori University, Tottori, Japan
| | - Yoshiaki Hikasa
- Joint Department of Veterinary Medicine, Faculty of Agriculture, Tottori University, Tottori, Japan
| | - Kazuo Azuma
- Joint Department of Veterinary Medicine, Faculty of Agriculture, Tottori University, Tottori, Japan
| | - Tomohiro Imagawa
- Joint Department of Veterinary Medicine, Faculty of Agriculture, Tottori University, Tottori, Japan
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Williamson EJ, Soares JH, Henao-Guerrero N, Council-Troche RM, Pavlisko ND. Cardiovascular and respiratory effects of two doses of fentanyl in the presence or absence of bradycardia in isoflurane-anesthetized dogs. Vet Anaesth Analg 2018; 45:423-431. [PMID: 29716836 DOI: 10.1016/j.vaa.2018.03.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2017] [Revised: 02/27/2018] [Accepted: 03/02/2018] [Indexed: 10/17/2022]
Abstract
OBJECTIVE To compare the cardiopulmonary effects of low and high doses of fentanyl before and after the correction of bradycardia in isoflurane-anesthetized dogs. STUDY DESIGN Prospective, randomized crossover trial. ANIMALS Eight healthy male Beagle dogs weighing 11.1 ± 1.3 kg [mean ± standard deviation (SD)] and aged approximately 1 year. METHODS The dogs were anesthetized with isoflurane [1.3 × minimum alveolar concentration (MAC)] on two occasions and fentanyl was administered intravenously; either low-dose fentanyl, loading dose (33 μg kg-1) and infusion (0.2 μg kg-1 minute-1) or a high-dose, loading dose (102 μg kg-1) and infusion (0.8 μg kg-1 minute-1). Cardiopulmonary variables were measured at three time points in equipotent isoflurane concentrations (1.3 MAC): before fentanyl administration (ISO), during fentanyl-induced bradycardia (ISO-F) and after administration of glycopyrrolate normalized heart rate (ISO-FNHR). Data are mean ± SD. RESULTS Heart rate and cardiac index (CI) decreased and systemic vascular resistance index (SVRI) increased at ISO-F in both treatments. Bradycardia and vasoconstriction at ISO-F were greater in high than in low-dose fentanyl (42 ± 7 versus 57 ± 15 beats minute-1 and 3457 ± 1108 versus 2528 ± 968 dyne second cm-5 m-2), respectively. Oxygen delivery index (DO2I) decreased only during high-dose fentanyl. CI and DO2I were higher in both treatments at ISO-FNHR than at ISO-F; however, they were higher only during the high-dose fentanyl than at ISO. SVRI was higher at ISO-F than at ISO and ISO-FNHR in both treatments, and was higher at ISO-F in the high than in the low-dose treatment. CONCLUSIONS AND CLINICAL RELEVANCE An overall improvement in cardiovascular function of dogs anesthetized with equipotent isoflurane doses (1.3 MAC) was observed after the treatment of bradycardia only with the high-dose fentanyl.
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Affiliation(s)
- Ellen J Williamson
- Department of Small Animal Clinical Sciences, Virginia-Maryland College of Veterinary Medicine, Virginia Tech, Blacksburg, VA, USA
| | - Joao Hn Soares
- Department of Small Animal Clinical Sciences, Virginia-Maryland College of Veterinary Medicine, Virginia Tech, Blacksburg, VA, USA.
| | - Natalia Henao-Guerrero
- Department of Small Animal Clinical Sciences, Virginia-Maryland College of Veterinary Medicine, Virginia Tech, Blacksburg, VA, USA
| | - Roberto McAlister Council-Troche
- Laboratory of Toxicology, Department of Biomedical Sciences and Pathobiology, Virginia-Maryland College of Veterinary Medicine, Virginia Tech, Blacksburg, VA, USA
| | - Noah D Pavlisko
- Department of Small Animal Clinical Sciences, Virginia-Maryland College of Veterinary Medicine, Virginia Tech, Blacksburg, VA, USA
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Murahata Y, Hikasa Y, Hayashi S, Shigematsu K, Akashi N, Osaki T, Tsuka T, Okamoto Y, Imagawa T. The effect of remifentanil on the minimum alveolar concentration (MAC) and MAC derivatives of sevoflurane in dogs. J Vet Med Sci 2018; 80:1086-1093. [PMID: 29780077 PMCID: PMC6068302 DOI: 10.1292/jvms.18-0122] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Remifentanil is an ultra-short-acting µ-opioid receptor agonist. The purpose of this study was to determine the relationship of the minimum alveolar concentration (MAC) of
sevoflurane and other MAC derivatives, including the MAC for blocking adrenergic responses (MAC-BAR) and the MAC at which tracheal extubation is occurred (MAC-extubation), with or without
remifentanil infusion. Six healthy adult beagle dogs were randomly anesthetized three times for determining the MAC-BAR (SEVMAC-BAR), MAC (SEVMAC), and MAC- extubation
(SEVMAC-extubation) of sevoflurane under infusion of saline and remifentanil at rates of 0.15, 0.30, 0.60, 1.20, and 2.40 µg/kg/min. The ratio of the
SEVMAC-BAR and SEVMAC and that of the SEVMAC-extubation and SEVMAC were not significantly different at baseline and during treatment. The
MAC-BAR95 and MAC95 decreased in a dose-dependent manner until reaching 1.20 µg/kg/min, and the MAC-extubation5 decreased in a
dose-dependent manner until reaching 0.60 µg/kg/min. The percentage reduction of SEVMAC-BAR, SEVMAC, and SEVMAC-extubation increased in a
dose-dependent manner during remifentanil infusion. The heart rate significantly decreased in the MAC-BAR and MAC groups, and the systolic and mean arterial pressures increased after
remifentanil infusion compared with the baseline values. Remifentanil infusion caused reduction of the SEVMAC-BAR, SEVMAC, and SEVMAC-extubation in a
dose-dependent manner, and ceiling effects were observed in the dogs. Higher doses of remifentanil and sevoflurane were necessary for blocking the sympathetic response to the supramaximal
stimulus to prevent movement and extubation in dogs.
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Affiliation(s)
- Yusuke Murahata
- Joint Department of Veterinary Medicine, Faculty of Agriculture, Tottori University, 4-101 Koyama-Minami, Tottori 680-8553, Japan
| | - Yoshiaki Hikasa
- Joint Department of Veterinary Medicine, Faculty of Agriculture, Tottori University, 4-101 Koyama-Minami, Tottori 680-8553, Japan
| | - Sho Hayashi
- Joint Department of Veterinary Medicine, Faculty of Agriculture, Tottori University, 4-101 Koyama-Minami, Tottori 680-8553, Japan
| | - Koki Shigematsu
- Joint Department of Veterinary Medicine, Faculty of Agriculture, Tottori University, 4-101 Koyama-Minami, Tottori 680-8553, Japan
| | - Natsuki Akashi
- Joint Department of Veterinary Medicine, Faculty of Agriculture, Tottori University, 4-101 Koyama-Minami, Tottori 680-8553, Japan
| | - Tomohiro Osaki
- Joint Department of Veterinary Medicine, Faculty of Agriculture, Tottori University, 4-101 Koyama-Minami, Tottori 680-8553, Japan
| | - Takeshi Tsuka
- Joint Department of Veterinary Medicine, Faculty of Agriculture, Tottori University, 4-101 Koyama-Minami, Tottori 680-8553, Japan
| | - Yoshiharu Okamoto
- Joint Department of Veterinary Medicine, Faculty of Agriculture, Tottori University, 4-101 Koyama-Minami, Tottori 680-8553, Japan
| | - Tomohiro Imagawa
- Joint Department of Veterinary Medicine, Faculty of Agriculture, Tottori University, 4-101 Koyama-Minami, Tottori 680-8553, Japan
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Dias RSG, Soares JHN, Castro DDSE, Gress MAKDA, Machado ML, Otero PE, Ascoli FO. Cardiovascular and respiratory effects of lumbosacral epidural bupivacaine in isoflurane-anesthetized dogs: The effects of two volumes of 0.25% solution. PLoS One 2018; 13:e0195867. [PMID: 29668768 PMCID: PMC5906007 DOI: 10.1371/journal.pone.0195867] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2017] [Accepted: 03/30/2018] [Indexed: 12/04/2022] Open
Abstract
The purpose of this study was to compare cardiovascular and respiratory effects of two volumes of bupivacaine 0.25% (0.2 mL kg-1-treatment BUP02-and 0.4 mL kg-1 -treatment BUP04) administered epidurally at the lumbosacral intervertebral space in dogs anesthetized with isoflurane. This experimental prospective randomized crossover design trial used six mixed breed adult dogs, four neutered males and two spayed females. Each dog was anesthetized on three different occasions: the first for isoflurane minimum alveolar concentration (MAC) measurement, and the following two assigned treatments (BUP02 or BUP04). On the two treatment days, anesthesia was induced and maintained with isoflurane at 1.3 MAC during the experiments. Cardiovascular and respiratory measurements were recorded before (T0) and 5, 15, 30, 60 and 90 minutes after the epidural administration of bupivacaine. Comparisons between and within groups were performed by a mixed-model ANOVA and Friedman's test when appropriate followed by Bonferroni post-hoc test or Dunnet's test to compare time points within each treatment with T0 (p < 0.05). Mean arterial pressure decreased significantly from 15 to 90 minutes after the administration of BUP02 and from 5 to 60 minutes in BUP04, with lower values in BUP04 than in BUP02 lasting up to 30 minutes after bupivacaine administration. No significant changes in cardiac output and systemic vascular resistance were observed in either treatment. Hypoventilation was only detected in BUP04. Hemoglobin concentration and arterial oxygen content decreased after both treatment of bupivacaine with no significant decrease in oxygen delivery. Two dogs in BUP04 developed Horner's syndrome. The epidural administration of 0.4 mL.kg-1 of bupivacaine to dogs in sternal recumbency anesthetized with isoflurane 1.3 MAC caused more cardiovascular and respiratory depression than 0.2 mL.kg-1.
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Affiliation(s)
- Raquel Sartori Gonçalves Dias
- Graduate Program in Cardiovascular Sciences, College of Medicine, Fluminense Federal University (UFF), Niterói, Rio de Janeiro, Brazil
| | - João Henrique Neves Soares
- Department of Small Animal Clinical Sciences, Virginia–Maryland Regional College of Veterinary Medicine, Virginia Tech, Blacksburg, Virginia, United States of America
| | - Douglas dos Santos e Castro
- Department of Large Animal Clinical Sciences, Anesthesia and Pain Management Service, University of Florida, Gainesville, Florida, United States of America
| | | | - Marcela Lemos Machado
- Graduate Program in Cardiovascular Sciences, College of Medicine, Fluminense Federal University (UFF), Niterói, Rio de Janeiro, Brazil
| | - Pablo E. Otero
- Universidad de Buenos Aires, Facultad de Ciencias Veterinarias, Cátedra de Anestesiología y Algiología, Buenos Aires, Argentina
| | - Fabio Otero Ascoli
- Graduate Program in Cardiovascular Sciences, College of Medicine, Fluminense Federal University (UFF), Niterói, Rio de Janeiro, Brazil
- Department of Physiology and Pharmacology, Biomedical Institute, Fluminense Federal University, Niterói, Rio de Janeiro, Brazil
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Williamson EJ, Soares JHN, Pavlisko ND, McAlister Council-Troche R, Henao-Guerrero N. Isoflurane minimum alveolar concentration sparing effects of fentanyl in the dog. Vet Anaesth Analg 2017; 44:738-745. [PMID: 28701288 DOI: 10.1016/j.vaa.2017.02.002] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2016] [Revised: 02/08/2017] [Accepted: 02/10/2017] [Indexed: 11/21/2022]
Abstract
OBJECTIVE To characterize the isoflurane-sparing effects of a high and a low dose of fentanyl in dogs, and its effects on mean arterial pressure (MAP) and heart rate (HR). STUDY DESIGN Prospective, randomized crossover trial. ANIMALS Eight healthy male Beagle dogs weighing 12.1 ± 1.6 kg [mean ± standard deviation (SD)] and approximate age 1 year. METHODS Dogs were anesthetized using isoflurane and minimum alveolar concentration (MAC) was determined in duplicate by the bracketing method using an electrical stimulus on the tarsus. Animals were administered fentanyl: low dose (33 μg kg-1 loading dose, 0.2 μg kg-1 minute-1) or high dose (102 μg kg-1 loading dose, 0.8 μg kg-1 minute-1) and MAC was re-determined (MACISO-F). Blood was collected for analysis of plasma fentanyl concentrations before administration and after MACISO-F determination. All values are presented as mean ± SD. RESULTS Isoflurane MAC (MACISO) was 1.30 ± 0.23% in the low dose treatment, which significantly decreased to 0.75 ± 0.22% (average MAC reduction 42.3 ± 9.4%). MACISO was 1.30 ± 0.18% in the high dose treatment, which significantly decreased to 0.30 ± 0.11% (average MAC reduction 76.9 ± 7.4%). Mean fentanyl plasma concentrations were 6.2 and 29.5 ng mL-1 for low and high dose treatments, respectively. MAP increased significantly only in the high dose treatment (from 81 ± 8 to 92 ± 9 mmHg). HR decreased significantly in both treatments from 108 ± 25 to 61 ± 14 beats minute-1 with the low dose and from 95 ± 14 to 42 ± 4 beats minute-1 with the high dose. CONCLUSIONS AND CLINICAL RELEVANCE Fentanyl administration resulted in a dose-dependent isoflurane MAC-sparing effect with bradycardia at both doses and an increase in MAP only at high dose. Further evaluation is needed to determine the effects of fentanyl on the overall cardiovascular function.
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Affiliation(s)
- Ellen J Williamson
- Department of Small Animal Clinical Sciences, Virginia-Maryland College of Veterinary Medicine, Virginia Tech, Blacksburg, VA, USA
| | - Joao H N Soares
- Department of Small Animal Clinical Sciences, Virginia-Maryland College of Veterinary Medicine, Virginia Tech, Blacksburg, VA, USA.
| | - Noah D Pavlisko
- Department of Small Animal Clinical Sciences, Virginia-Maryland College of Veterinary Medicine, Virginia Tech, Blacksburg, VA, USA
| | - Robert McAlister Council-Troche
- Laboratory of Toxicology, Department of Biomedical Sciences and Pathobiology, Virginia-Maryland College of Veterinary Medicine, Virginia Tech, VA, USA
| | - Natalia Henao-Guerrero
- Department of Small Animal Clinical Sciences, Virginia-Maryland College of Veterinary Medicine, Virginia Tech, Blacksburg, VA, USA
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Tearney CC, Barter LS, Pypendop BH. Cardiovascular effects of equipotent doses of isoflurane alone and isoflurane plus fentanyl in New Zealand White rabbits (Oryctolagus cuniculus). Am J Vet Res 2016; 76:591-8. [PMID: 26111088 DOI: 10.2460/ajvr.76.7.591] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
OBJECTIVE To determine effects of equipotent concentrations of fentanyl and isoflurane, compared with isoflurane alone, on cardiovascular variables in New Zealand White rabbits (Oryctolagus cuniculus). ANIMALS 6 adult female New Zealand White rabbits. PROCEDURES Rabbits were anesthetized with isoflurane, and lungs were mechanically ventilated. The minimum alveolar concentration (MAC) of isoflurane alone (baseline) and with fentanyl administered IV to achieve 3 targeted plasma concentrations was determined for each rabbit by means of an electrical stimulus. Cardiovascular variables were measured in a separate experiment at 1.3X isoflurane MAC and equipotent doses of isoflurane plus fentanyl at the same 3 targeted plasma concentrations. Blood samples were collected for measurement of blood gas variables and plasma fentanyl concentrations. Treatment effects were evaluated by repeated-measures ANOVA followed by 2-tailed paired t tests with sequentially rejective Bonferroni correction. RESULTS Mean ± SD MAC of isoflurane was 1.95 ± 0.27%. Mean measured plasma fentanyl concentrations of 4.97, 8.93, and 17.19 ng/mL reduced isoflurane MAC by 17%, 37%, and 56%, respectively. Mean measured plasma fentanyl concentrations during cardiovascular measurements were 5.49, 10.26, and 18.40 ng/mL. Compared with baseline measurements, heart rate was significantly lower at all 3 plasma fentanyl concentrations, mean arterial blood pressure and systemic vascular resistance were significantly higher at mean fentanyl concentrations of 10.26 and 18.40 ng/mL, and cardiac output was significantly higher at 18.40 ng of fentanyl/mL. CONCLUSIONS AND CLINICAL RELEVANCE Administration of fentanyl in isoflurane-anesthetized rabbits resulted in improved mean arterial blood pressure and cardiac output, compared with isoflurane alone. This balanced anesthesia technique may prove useful in the management of clinical cases in this species.
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Simões CR, Monteiro ER, Rangel JPP, Nunes-Junior JS, Campagnol D. Effects of a prolonged infusion of fentanyl, with or without atropine, on the minimum alveolar concentration of isoflurane in dogs. Vet Anaesth Analg 2015; 43:136-44. [PMID: 26058733 DOI: 10.1111/vaa.12282] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2014] [Accepted: 03/07/2015] [Indexed: 11/30/2022]
Abstract
OBJECTIVES To evaluate the effect of a prolonged constant rate infusion (CRI) of fentanyl on the minimum alveolar concentration (MAC) of isoflurane (ISOMAC ) and to establish whether concurrent atropine administration influences ISOMAC in dogs. STUDY DESIGN Prospective, crossover study. ANIMALS Six healthy dogs weighing 13.0 ± 4.1 kg. METHODS Dogs were anesthetized with isoflurane under conditions of normocapnia and normothermia. Arterial blood pressure was monitored invasively. Each dog was administered two treatments, on different occasions, in a crossover design. The dogs were administered intravenously (IV) an atropine bolus 0.02 mg kg(-1) and CRI at 0.04 mg kg(-1) hour(-1) (fentanyl-atropine treatment) or no atropine (fentanyl treatment). For each dog, baseline ISOMAC was measured in duplicate using a tail clamp technique. Subsequently, all dogs were administered a fentanyl bolus (5 μg kg(-1)) and CRI (9 μg kg(-1) hour(-1)) IV, and ISOMAC was re-determined at 120 and 300 minutes after initiation of the fentanyl CRI. RESULTS Baseline ISOMAC values in the fentanyl and fentanyl-atropine treatments were 1.38 ± 0.16% and 1.39 ± 0.14%, respectively. Fentanyl significantly decreased the ISOMAC by 50 ± 9% and 47 ± 13% after 120 minutes and by 51 ± 14% and 50 ± 9% after 300 minutes (p < 0.001) in the fentanyl and fentanyl-atropine treatments, respectively. Compared with baseline, heart rate decreased significantly in the fentanyl treatment by 35% and 43% at 120 and 300 minutes, respectively. In the fentanyl-atropine treatment, heart rate did not change significantly over time. In both treatments, systolic arterial pressure increased from baseline after fentanyl. CONCLUSIONS AND CLINICAL RELEVANCE In this study, fentanyl reduced the ISOMAC by approximately 50%. The ISOMAC remained stable throughout the 300 minute CRI of fentanyl, suggesting no cumulative effect of the opioid. Atropine did not influence ISOMAC in dogs.
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Affiliation(s)
- Clarissa R Simões
- School of Veterinary Medicine, University of Vila Velha, Vila Velha, ES, Brazil
| | - Eduardo R Monteiro
- School of Veterinary Medicine, University of Vila Velha, Vila Velha, ES, Brazil
| | - Julia P P Rangel
- School of Veterinary Medicine, University of Vila Velha, Vila Velha, ES, Brazil
| | | | - Daniela Campagnol
- School of Veterinary Medicine, University of Vila Velha, Vila Velha, ES, Brazil
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Barter LS, Epstein SE. Cardiopulmonary effects of three concentrations of isoflurane with or without mechanical ventilation and supramaximal noxious stimulation in New Zealand white rabbits. Am J Vet Res 2013; 74:1274-80. [DOI: 10.2460/ajvr.74.10.1274] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Campagnol D, Teixeira-Neto FJ, Peccinini RG, Oliveira FA, Alvaides RK, Medeiros LQ. Comparison of the effects of epidural or intravenous methadone on the minimum alveolar concentration of isoflurane in dogs. Vet J 2012; 192:311-5. [DOI: 10.1016/j.tvjl.2011.08.019] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2010] [Revised: 08/10/2011] [Accepted: 08/16/2011] [Indexed: 10/17/2022]
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