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James LE, Bertelsen MF, Wang T, Williams CJA. Impact of procedural handling on the physiological effects of alfaxalone anaesthesia in the ball python (Python regius). Comp Biochem Physiol A Mol Integr Physiol 2024; 297:111704. [PMID: 39038601 DOI: 10.1016/j.cbpa.2024.111704] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2024] [Revised: 07/17/2024] [Accepted: 07/17/2024] [Indexed: 07/24/2024]
Abstract
To describe the cardiovascular changes following intramuscular (handled) and intravascular (undisturbed, via intraarterial catheter) alfaxalone administration, we studied 20 healthy ball pythons (Python regius) in a randomised, prospective study. The pythons were instrumented with occlusive arterial catheters to facilitate undisturbed, continuous monitoring of heart rate and blood pressure. Six pythons were administered intramuscular (IM) saline, followed by 20 mg/kg IM alfaxalone, and were manually restrained for both injections. Six pythons received intraarterial (IA) saline, followed by 10 mg/kg IA alfaxalone, and remained undisturbed for both injections. Arterial blood samples were taken at 0, 12 and 60 min post-injection, and heart rate and blood pressure were recorded for 60 min. The remaining eight snakes received 20 mg/kg IM or 10 mg/kg IA alfaxalone (n = 4 per treatment) and were not handled for intubation 10 min post-injection, to examine the effects of handling during anaesthesia. IM administration of 20 mg/kg alfaxalone or an equivalent volume of saline elicited a profound tachycardia and hypertension, which recovered to resting values after 20 min. However, when 10 mg/kg alfaxalone or saline were injected IA, mild hypotension and a lower magnitude tachycardia occurred. Arterial PCO2 and PO2, pH and lactate concentrations did not change following IA alfaxalone, but an acidosis was observed during IM alfaxalone anaesthesia. There were no significant changes in plasma catecholamines and corticosterone among treatments. Handling for injection and during anaesthesia associated with intubation significantly affects cardiovascular parameters, whereas alfaxalone per se only elicits minor changes in cardiovascular physiology.
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Affiliation(s)
- Lauren E James
- Section for Zoophysiology, Department of Biology, Aarhus University, Aarhus, Denmark
| | - Mads F Bertelsen
- Centre for Zoo and Wild Animal Health, Copenhagen Zoo, Copenhagen, Denmark
| | - Tobias Wang
- Section for Zoophysiology, Department of Biology, Aarhus University, Aarhus, Denmark. https://twitter.com/Tobias_Wang_AU
| | - Catherine J A Williams
- Section for Zoophysiology, Department of Biology, Aarhus University, Aarhus, Denmark; Department of Animal and Veterinary Science, Aarhus University, Tjele, Denmark.
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2
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Last KB, Malte H, Rindom E, Guagnoni IN, Wang T. Proportional increment of oxygen consumption, heart rate and core body temperature in the digesting Python bivittatus. J Exp Biol 2024; 227:jeb248021. [PMID: 39319390 DOI: 10.1242/jeb.248021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2024] [Accepted: 09/03/2024] [Indexed: 09/26/2024]
Abstract
The Burmese python has a remarkable digestive physiology with large elevations of metabolic rate and heart rate following feeding. Here, we investigated the relationship between heart rate, oxygen consumption and core body temperature during digestion in five pythons (Python bivittatus) by implantation of data loggers. The snakes were placed in respirometers at 30±0.1°C for 26 days and voluntarily ingested three meals of different size, whilst heart rate, core body temperature and oxygen consumption rate were measured continuously. Both oxygen consumption and heart rate increased severalfold during digestion, and metabolic heat production increased core body temperature by 2°C, explaining 12% of the observed tachycardia. The rise in core body temperature means that standard metabolic rate increased during digestion, and we estimate that failure to account for core body temperature leads to a 4% overestimation of the specific dynamic action (SDA) response. Our study reveals a close correlation between oxygen consumption and heart rate during digestion, further supporting the use of heart rate as a proxy for metabolism.
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Affiliation(s)
- Katja B Last
- Zoophysiology, Department of Biology, Aarhus University, Universitetsparken, 8000 Aarhus C, Denmark
| | - Hans Malte
- Zoophysiology, Department of Biology, Aarhus University, Universitetsparken, 8000 Aarhus C, Denmark
| | - Emil Rindom
- Zoophysiology, Department of Biology, Aarhus University, Universitetsparken, 8000 Aarhus C, Denmark
| | - Igor N Guagnoni
- Zoophysiology, Department of Biology, Aarhus University, Universitetsparken, 8000 Aarhus C, Denmark
| | - Tobias Wang
- Zoophysiology, Department of Biology, Aarhus University, Universitetsparken, 8000 Aarhus C, Denmark
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3
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Guagnoni IN, Last KB, Rindom E, Wang T. The pancreas does not contribute to the non-adrenergic-non-cholinergic stimulation of heart rate in digesting pythons. Comp Biochem Physiol A Mol Integr Physiol 2024; 291:111608. [PMID: 38373589 DOI: 10.1016/j.cbpa.2024.111608] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2024] [Revised: 02/15/2024] [Accepted: 02/16/2024] [Indexed: 02/21/2024]
Abstract
Vertebrates elevate heart rate when metabolism increases during digestion. Part of this tachycardia is due to a non-adrenergic-non-cholinergic (NANC) stimulation of the cardiac pacemaker, and it has been suggested these NANC factors are circulating hormones that are released from either gastrointestinal or endocrine glands. The NANC stimulation is particularly pronounced in species with large metabolic responses to digestion, such as reptiles. To investigate the possibility that the pancreas may release hormones that exert positive chronotropic effects on the digesting Burmese python heart, a species with very large postprandial changes in heart rate and oxygen uptake, we evaluate how pancreatectomy affects postprandial heart rate before and after autonomic blockade of the muscarinic and the beta-adrenergic receptors. We also measured the rates of oxygen consumption and evaluated the short-term control of the heart using the spectral analysis of heart rate variability and the baroreflex sequence method. Digestion caused the ubiquitous tachycardia, but the intrinsic heart rate (revealed after the combination of atropine and propranolol) was not affected by pancreatectomy and therefore hormones, such as glucagon and insulin, do not appear to contribute to the regulation of heart rate during digestion in Burmese pythons.
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Affiliation(s)
- Igor Noll Guagnoni
- Section for Zoophysiology, Department of Biology, Aarhus University, Aarhus, Denmark; Department of Biological Sciences, São Paulo State University (UNESP), Rua Cristóvão Colombo, 2265, São José do Rio Preto, SP 15054-000, Brazil.
| | - Katja Bundgaard Last
- Section for Zoophysiology, Department of Biology, Aarhus University, Aarhus, Denmark
| | - Emil Rindom
- Section for Zoophysiology, Department of Biology, Aarhus University, Aarhus, Denmark
| | - Tobias Wang
- Section for Zoophysiology, Department of Biology, Aarhus University, Aarhus, Denmark
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4
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Morrison HL, Rasys AM, Quandt JE, Divers SJ. Retrospective assessment of general anesthesia-related challenges, morbidity, and death in snakes: 139 cases (2000-2022). J Am Vet Med Assoc 2023; 261:536-543. [PMID: 36656677 DOI: 10.2460/javma.22.10.0477] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
OBJECTIVE To summarize the anesthetic events of snakes seen at a large university hospital, identify challenges with record keeping, and assess patient and anesthesia-related morbidity and death. SAMPLE 139 anesthetic events were performed; only 106 cases had detailed anesthetic reports available for further analyses. PROCEDURES Medical records of snakes that underwent general anesthesia between October 2000 and January 2022 were retrospectively reviewed. Only cases with complete anesthesia records were used to assess anesthetic parameters. Collected data included general patient details, diagnoses, procedures, premedication, induction, maintenance, monitoring, and recovery. RESULTS A thorough review of the records identified issues or scenarios that resulted in poor record management as well as highlighted the most frequently used anesthetics in snakes. For premedication this was alfaxalone, butorphanol, and hydromorphone, whereas isoflurane, alfaxalone, or propofol were the most common with induction. Lastly, with maintenance, isoflurane was the most popular choice. Of the 139 cases performed, 127 animals recovered, 8 were euthanatized due to poor prognosis, and 4 failed to recover. All snakes that failed to recover had preexisting disease identified pre-, peri-, or postoperatively at necropsy. CLINICAL RELEVANCE General anesthesia can be reliably and safely undertaken in snakes without severe preexisting disease. Efforts should be directed at identifying preexisting disease and maintaining and completing anesthesia records, and we recommend an auditing system to identify and correct issues as they arise.
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Affiliation(s)
- Heather L Morrison
- 1Department of Small Animal Medicine and Surgery, College of Veterinary Medicine, University of Georgia, Athens, GA
| | - Ashley M Rasys
- 1Department of Small Animal Medicine and Surgery, College of Veterinary Medicine, University of Georgia, Athens, GA
- 2Department of Cellular Biology, Franklin College of Arts and Sciences, University of Georgia, Athens, GA
| | - Jane E Quandt
- 1Department of Small Animal Medicine and Surgery, College of Veterinary Medicine, University of Georgia, Athens, GA
| | - Stephen J Divers
- 1Department of Small Animal Medicine and Surgery, College of Veterinary Medicine, University of Georgia, Athens, GA
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5
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Obesity prolongs induction times in reptiles. Comp Biochem Physiol A Mol Integr Physiol 2022; 271:111255. [PMID: 35659976 DOI: 10.1016/j.cbpa.2022.111255] [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: 02/17/2022] [Revised: 05/24/2022] [Accepted: 05/30/2022] [Indexed: 11/22/2022]
Abstract
Obesity is common in captive reptiles, and reptiles are increasingly popular as companion animals and in physiological research. Obesity may present a challenge during surgical procedures using inhalation anaesthesia, as the long induction time due to the low reptilian metabolism may increase anaesthetic accumulation in the adipose tissues. This study investigated the impact of obesity on induction and recovery times from inhaled anaesthesia. The temporal change in the partial pressure of isoflurane in different tissues was predicted using a multi-compartment model. Furthermore, as right-to-left shunting can delay anaesthetic uptake and washout, we included an assessment of the combination of cardiac shunting and obesity. The model predictions indicate a clear increase in time to reach 90% equilibration of administered anaesthetic in the brain (T90) of obese non-shunting (lean 47 min, obese >100 min) and shunting (lean 81 min, obese >100 min) reptiles. The combination of obesity and shunting doubled the time to acquisition of mean anaesthetic concentration (a measure used to plan anaesthesia) from 8 min to 19 min. Adipose blood flow highly affected whether the body type had an impact on induction time, with low adipose blood flow abolishing the effect of body type. As T90 was never reached within 100 min with both the obese reptiles, it was not possible to conclude on the effect of obesity on recovery times within this study. Care should therefore be taken when anaesthetising obese reptiles for surgical purposes, to ensure adequate anaesthetic depth is attained, and recovery monitored closely.
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Yenmiş M, Bayrakcı Y, Ayaz D. Hierarchical microstructure of the scales in grass snake (Natrix natrix) and dice snake (Natrix tessellata). Biologia (Bratisl) 2022. [DOI: 10.1007/s11756-022-01034-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
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Boukens BJD, Joyce W, Kristensen DL, Hooijkaas I, Jongejan A, Wang T, Jensen B. Catecholamines are key modulators of ventricular repolarization patterns in the ball python (Python regius). J Gen Physiol 2022; 154:212914. [PMID: 34910097 PMCID: PMC8679508 DOI: 10.1085/jgp.202012761] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2020] [Revised: 10/28/2021] [Accepted: 11/19/2021] [Indexed: 12/13/2022] Open
Abstract
Ectothermic vertebrates experience daily changes in body temperature, and anecdotal observations suggest these changes affect ventricular repolarization such that the T-wave in the ECG changes polarity. Mammals, in contrast, can maintain stable body temperatures, and their ventricular repolarization is strongly modulated by changes in heart rate and by sympathetic nervous system activity. The aim of this study was to assess the role of body temperature, heart rate, and circulating catecholamines on local repolarization gradients in the ectothermic ball python (Python regius). We recorded body-surface electrocardiograms and performed open-chest high-resolution epicardial mapping while increasing body temperature in five pythons, in all of which there was a change in T-wave polarity. However, the vector of repolarization differed between individuals, and only a subset of leads revealed T-wave polarity change. RNA sequencing revealed regional differences related to adrenergic signaling. In one denervated and Ringer's solution-perfused heart, heating and elevated heart rates did not induce change in T-wave polarity, whereas noradrenaline did. Accordingly, electrocardiograms in eight awake pythons receiving intra-arterial infusion of the β-adrenergic receptor agonists adrenaline and isoproterenol revealed T-wave inversion in most individuals. Conversely, blocking the β-adrenergic receptors using propranolol prevented T-wave change during heating. Our findings indicate that changes in ventricular repolarization in ball pythons are caused by increased tone of the sympathetic nervous system, not by changes in temperature. Therefore, ventricular repolarization in both pythons and mammals is modulated by evolutionary conserved mechanisms involving catecholaminergic stimulation.
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Affiliation(s)
- Bastiaan J D Boukens
- University of Amsterdam, Amsterdam UMC, Department of Medical Biology, Amsterdam Cardiovascular Sciences, Amsterdam, The Netherlands
| | - William Joyce
- Department of Biology, Zoophysiology, Aarhus University, Aarhus, Denmark
| | | | - Ingeborg Hooijkaas
- University of Amsterdam, Amsterdam UMC, Department of Medical Biology, Amsterdam Cardiovascular Sciences, Amsterdam, The Netherlands
| | - Aldo Jongejan
- University of Amsterdam, Amsterdam UMC, Department of Epidemiology & Data Science, Amsterdam, The Netherlands
| | - Tobias Wang
- Department of Biology, Zoophysiology, Aarhus University, Aarhus, Denmark
| | - Bjarke Jensen
- University of Amsterdam, Amsterdam UMC, Department of Medical Biology, Amsterdam Cardiovascular Sciences, Amsterdam, The Netherlands
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Abstract
Snakes can be more challenging to anesthetize compared with other animals because of anatomic and physiologic differences, a wide range of patient sizes, and variable responses to anesthetic agents. Snakes have preferred optimal temperature zones, which, along with physiologic characteristics, such as the ability to shunt blood toward or away from the lungs, can have an impact on anesthesia. Injectable agents, including benzodiazepines, α2-agonists, opioids, propofol, and alfaxalone, as well as inhalant anesthetics can be used to anesthetize snakes. Pain management must be incorporated to the anesthetic plan when performing procedures that are expected to produce nociception.
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Affiliation(s)
- Daniel Almeida
- Veterinary Clinical Sciences, College of Veterinary Medicine, University of Minnesota, 1352 Boyd Avenue, Saint Paul, MN 55108, USA.
| | - Martin Kennedy
- Veterinary Clinical Sciences, College of Veterinary Medicine, University of Minnesota, 1352 Boyd Avenue, Saint Paul, MN 55108, USA
| | - Erin Wend-Hornickle
- Veterinary Clinical Sciences, College of Veterinary Medicine, University of Minnesota, 1352 Boyd Avenue, Saint Paul, MN 55108, USA
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9
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Williams CJA, Hansen K, Williams N, Jakobsen SR, Pedersen CCE, Bertelsen MF, Wang T. The influence of assisted ventilation and recumbency on cardiorespiratory physiology in the anesthetized freshwater turtle Trachemys scripta scripta. Comp Biochem Physiol A Mol Integr Physiol 2021; 260:111036. [PMID: 34256130 DOI: 10.1016/j.cbpa.2021.111036] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2021] [Revised: 06/15/2021] [Accepted: 07/08/2021] [Indexed: 11/18/2022]
Abstract
The use of assisted ventilation is required in anesthetized reptiles as their respiratory drive is lost at surgical depths of anesthesia. The minute volume of the assisted ventilation influences arterial blood gases and acid-base regulation. Meanwhile, the ventilatory pattern may also affect hemodynamics in chelonians, which, given their large capacity for cardiac shunts, may impact the efficacy of the ventilation in terms of gas exchange. Hence, there is a need for primary information on the influence of assisted ventilation on chelonian physiology, and we, therefore, performed a randomized study into the effects of recumbency and maximum airway pressure on pressure-cycled ventilation in nine female Trachemys scripta scripta. Pronounced effects of ventilation pressure on arterial PCO2 and pH regardless of recumbency were revealed, whilst dorsal recumbency led to a larger Arterial-alveolar (A-a) O2 difference, suggesting compromised pulmonary gas exchange. Plasma [Na+] and [K+] balance was also significantly correlated with maximum airway pressure. Computed tomography (CT) scanning at a range of end-inspiratory pressures and ventral and dorsal recumbencies in eight T. scripta scripta showed that lung volumes increase with maximum ventilatory pressure, while recumbency did not influence volume at pressures above 5 cmH2O. Static compliance of the lungs was influenced by recumbency at neutral pressures. In conclusion, dorsal recumbency reduces pulmonary efficacy during positive pressure ventilation and tends to lower lung volume when ventilation is not provided. However, lung volumes and function - even in dorsal recumbency - can be adequately supported by assisted ventilation, and an end inspiratory pressure of 10 cmH2O at 4 breaths min-1 provided the most physiologically appropriate ventilation of anesthetized T. scripta scripta.
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Affiliation(s)
- Catherine J A Williams
- Zoophysiology, Department of Biology, Aarhus University, Denmark; Department of Biomedical Sciences, University of Guelph, Canada.
| | - Kasper Hansen
- Zoophysiology, Department of Biology, Aarhus University, Denmark; Department of Forensic Medicine, Aarhus University, Denmark; Department of Clinical Medicine (Comparative Medicine Lab), Aarhus University, Denmark
| | - Natasha Williams
- Zoophysiology, Department of Biology, Aarhus University, Denmark
| | | | | | | | - Tobias Wang
- Zoophysiology, Department of Biology, Aarhus University, Denmark
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10
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Bertelsen MF, Buchanan R, Jensen HM, Leite CAC, Abe AS, Wang T. Pharmacodynamics of propofol and alfaxalone in rattlesnakes (Crotalus durissus). Comp Biochem Physiol A Mol Integr Physiol 2021; 256:110935. [PMID: 33711440 DOI: 10.1016/j.cbpa.2021.110935] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Revised: 03/05/2021] [Accepted: 03/05/2021] [Indexed: 10/21/2022]
Abstract
To characterise the effect of two common induction agents, propofol and alfaxalone, on mean arterial blood pressure (MAP) and heart rate (HR), we equipped 19 adult South American rattlesnakes (Crotalus durissus) with an indwelling arterial catheter approximately 24 h prior to recording of baseline resting values. Then, seven snakes received alfaxalone (15 mg kg-1) intravascularly (IV) through the catheter, while groups two and three (both n = 6) received propofol (15 mg kg-1 IV). The first two groups were not handled, while the group 3 was manually restrained for 2 min for a mock injection of 0.2 ml saline into the ventral tail vein. Baseline HR was similar in all groups and handling caused a significant tachycardia (p = 0.031) in group three. When given IV to undisturbed animals, both propofol and alfaxalone induced a significant increase in HR (p = 0.0022 and p = 0.0045, respectively) lasting approximately 30 min, but with values only significantly exceeding baseline for the first 5 min for propofol and the first 10 min with alfaxalone. Handling caused a significant increase in MAP (p = 0.0313). Propofol did not affect MAP (p = 0.1064), while alfaxalone caused a marked hypertension (although only significant at 2 min; p = 0.031). Manual restraint significantly increases both HR and MAP, which may lead to a masking of true cardiovascular effects of anaesthetic agents.
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Affiliation(s)
- Mads F Bertelsen
- Centre for Zoo and Wild Animal Health, Copenhagen Zoo, Frederiksberg, Denmark; Departamento de Zoologia, Centro de Aquicultura, UNESP, Rio Claro, São Paulo, Brazil.
| | - Rasmus Buchanan
- Zoophysiology, Department of Biology, University of Aarhus, Denmark; Departamento de Zoologia, Centro de Aquicultura, UNESP, Rio Claro, São Paulo, Brazil
| | - Heidi M Jensen
- Zoophysiology, Department of Biology, University of Aarhus, Denmark; Departamento de Zoologia, Centro de Aquicultura, UNESP, Rio Claro, São Paulo, Brazil
| | - Cleo A C Leite
- Department of Physiological Sciences, UFSCar, São Carlos, São Paulo, Brazil; Departamento de Zoologia, Centro de Aquicultura, UNESP, Rio Claro, São Paulo, Brazil
| | - Augusto S Abe
- Centre for Zoo and Wild Animal Health, Copenhagen Zoo, Frederiksberg, Denmark
| | - Tobias Wang
- Zoophysiology, Department of Biology, University of Aarhus, Denmark; Departamento de Zoologia, Centro de Aquicultura, UNESP, Rio Claro, São Paulo, Brazil
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11
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Williams CJA, Malte CL, Malte H, Bertelsen MF, Wang T. Ectothermy and cardiac shunts profoundly slow the equilibration of inhaled anaesthetics in a multi-compartment model. Sci Rep 2020; 10:17157. [PMID: 33051496 PMCID: PMC7555730 DOI: 10.1038/s41598-020-74014-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2020] [Accepted: 09/21/2020] [Indexed: 01/08/2023] Open
Abstract
The use of inhalational anaesthesia is ubiquitous in terrestrial vertebrates. Given the dependence of these agents on delivery by the cardiorespiratory system, we developed a new computational model predicting equilibration of inhaled anaesthetics in mammalian and ectotherm conditions including the ability of reptiles to maintain vascular shunts. A multi-compartment model was constructed from simultaneously-solved equations, verified by comparison to the literature for endo and ectotherm physiology. The time to 90% equilibration of anaesthetic in arterial blood (t90) is predicted and used to compare anaesthetics and physiologies. The five to tenfold lower cardiac output and minute ventilation of ectothermic vertebrates is predicted to slow equilibration times by five to ten times leading to 90% equilibration in ectotherm arterial blood of over 200 min, compounded by reduction in body temperature, and the extent of right-to-left vascular shunts. The impact of these findings is also influenced by the solubility coefficient of the anaesthetic, such that at net right-to-left shunt fractions of over 0.8, sevoflurane loses the advantage of faster equilibration, in comparison with isoflurane. We explore clinical strategies to regulate anaesthetic uptake in ectotherms by managing convectional flow especially by supportive ventilation and reduction of the right-to-left shunt.
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Affiliation(s)
- Catherine J A Williams
- Section of Zoophysiology, Department of Biology, Aarhus University, 8000, Aarhus C, Denmark. .,Center for Zoo and Wild Animal Health, Copenhagen Zoo, Roskildevej 38, 2000, Frederiksberg, Denmark. .,Ontario Veterinary College, University of Guelph, 50 Stone Road E, Guelph, ON, N1G 2W1, Canada.
| | - Christian Lind Malte
- Section of Zoophysiology, Department of Biology, Aarhus University, 8000, Aarhus C, Denmark
| | - Hans Malte
- Section of Zoophysiology, Department of Biology, Aarhus University, 8000, Aarhus C, Denmark
| | - Mads F Bertelsen
- Center for Zoo and Wild Animal Health, Copenhagen Zoo, Roskildevej 38, 2000, Frederiksberg, Denmark
| | - Tobias Wang
- Section of Zoophysiology, Department of Biology, Aarhus University, 8000, Aarhus C, Denmark.,Aarhus Institute of Advanced Sciences, Aarhus University, 8000, Aarhus C, Denmark
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12
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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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13
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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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James LE, Williams CJA, Bertelsen MF, Wang T. Anaesthetic induction with alfaxalone in the ball python ( Python regius ): dose response and effect of injection site. Vet Anaesth Analg 2018; 45:329-337. [DOI: 10.1016/j.vaa.2017.12.003] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2017] [Revised: 12/13/2017] [Accepted: 12/30/2017] [Indexed: 11/29/2022]
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