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Basson EP, Kadwa AR, Blignaut CJ, Zeiler GE. Physiological variables for the objective detection of nerve block failure in dogs. Vet Anaesth Analg 2024; 51:343-353. [PMID: 38772854 DOI: 10.1016/j.vaa.2024.03.010] [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: 03/21/2023] [Revised: 02/29/2024] [Accepted: 03/25/2024] [Indexed: 05/23/2024]
Abstract
OBJECTIVE To identify physiological variables for objectively detecting nociception indicative of intraoperative peripheral nerve block failure. STUDY DESIGN A double-blinded randomized clinical study. ANIMALS A sample of 14 male (40.8 ± 12 kg; mean ± standard deviation) and 16 female (34.3 ± 11.4 kg) client-owned dogs. METHODS Dogs were randomly assigned to one of three groups for psoas compartment and proximal sciatic nerve blocks (0.2 mL kg-1 per site): guided bupivacaine (GBB), or saline (GSB) block or a blind bupivacaine block (BBB). Guided blocks were performed using an ultrasound-peripheral nerve locator combination. Premedication consisted of medetomidine 0.01 mg kg-1 and morphine 0.3 mg kg-1. General anaesthesia was induced with propofol and maintained with isoflurane in oxygen. Receiver operator characteristic curve analysis was used to compare actual values and change in values of physiological variables between GSB and GBB. The Youden index and associated criterion for each physiological variable were used to determine an objective measure for nociception. Fisher's exact t test, McNemar's test and Cohen's kappa statistical analysis were used to determine association, differences and inter-score reliability between the objective and subjective scoring for BBB. RESULTS Cardiovascular variables had good discriminating ability to identify a nociceptive response (p < 0.01). The Youden indices for mean (MAP) and diastolic (DAP) arterial pressure were most reliable in detecting nociception. The highest sensitivity was that of ΔMAP (100%) with good agreement between the subjective and objective scores of Δheart rate or systolic arterial pressure (SAP). The use of ΔMAP, ΔSAP, ΔDAP had the best ability in indicating peripheral nerve block failure (p < 0.001). CONCLUSIONS AND CLINICAL RELEVANCE Blood pressure values can detect a response to surgical stimulus in adequately anaesthetized dogs. The use of ΔMAP, ΔSAP or ΔDAP may be considered as objective measures to detect nerve block failure.
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Affiliation(s)
- Etienne P Basson
- Anaesthesia and Critical Care Services, Valley Farm Animal Hospital, Pretoria, South Africa; Department of Companion Animal Clinical Studies, Faculty of Veterinary Science, University of Pretoria, Pretoria, South Africa.
| | - Abdur R Kadwa
- Department of Companion Animal Clinical Studies, Faculty of Veterinary Science, University of Pretoria, Pretoria, South Africa
| | - Christiaan J Blignaut
- Department of Companion Animal Clinical Studies, Faculty of Veterinary Science, University of Pretoria, Pretoria, South Africa
| | - Gareth E Zeiler
- Anaesthesia and Critical Care Services, Valley Farm Animal Hospital, Pretoria, South Africa; Department of Companion Animal Clinical Studies, Faculty of Veterinary Science, University of Pretoria, Pretoria, South Africa
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2
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Weiss L, Saller AM, Werner J, Süß SC, Reiser J, Kollmansperger S, Anders M, Potschka H, Fenzl T, Schusser B, Baumgartner C. Nociception in Chicken Embryos, Part I: Analysis of Cardiovascular Responses to a Mechanical Noxious Stimulus. Animals (Basel) 2023; 13:2710. [PMID: 37684974 PMCID: PMC10486618 DOI: 10.3390/ani13172710] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2023] [Revised: 08/18/2023] [Accepted: 08/23/2023] [Indexed: 09/10/2023] Open
Abstract
Although it is assumed that chicken embryos acquire the capacity for nociception while developing in the egg, an exact time point has not yet been specified. The present research was an exploratory study aiming to determine when the capacity of nociception emerges during embryonic development in chickens. Changes in blood pressure and heart rate (HR) in response to a noxious mechanical stimulus at the base of the beak versus a light touch on the beak were examined in chicken embryos between embryonic days (EDs) 7 and 18. Mean arterial pressure (MAP) was the most sensitive parameter for assessing cardiovascular responses. Significant changes in MAP in response to a noxious stimulus were detected in embryos at ED16 to ED18, whereas significant changes in HR were observed at ED17 and ED18. Infiltration anesthesia with the local anesthetic lidocaine significantly reduced the response of MAP on ED18, so the measured cardiovascular changes may be interpreted as nociceptive responses.
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Affiliation(s)
- Larissa Weiss
- Center for Preclinical Research, TUM School of Medicine, Technical University of Munich, 81675 Munich, Germany; (L.W.); (A.M.S.); (J.W.); (S.C.S.); (J.R.)
| | - Anna M. Saller
- Center for Preclinical Research, TUM School of Medicine, Technical University of Munich, 81675 Munich, Germany; (L.W.); (A.M.S.); (J.W.); (S.C.S.); (J.R.)
| | - Julia Werner
- Center for Preclinical Research, TUM School of Medicine, Technical University of Munich, 81675 Munich, Germany; (L.W.); (A.M.S.); (J.W.); (S.C.S.); (J.R.)
| | - Stephanie C. Süß
- Center for Preclinical Research, TUM School of Medicine, Technical University of Munich, 81675 Munich, Germany; (L.W.); (A.M.S.); (J.W.); (S.C.S.); (J.R.)
| | - Judith Reiser
- Center for Preclinical Research, TUM School of Medicine, Technical University of Munich, 81675 Munich, Germany; (L.W.); (A.M.S.); (J.W.); (S.C.S.); (J.R.)
| | - Sandra Kollmansperger
- Clinic for Anesthesiology and Intensive Care, TUM School of Medicine, Technical University of Munich, 81675 Munich, Germany; (S.K.); (M.A.); (T.F.)
| | - Malte Anders
- Clinic for Anesthesiology and Intensive Care, TUM School of Medicine, Technical University of Munich, 81675 Munich, Germany; (S.K.); (M.A.); (T.F.)
| | - Heidrun Potschka
- Institute of Pharmacology, Toxicology, and Pharmacy, Ludwig-Maximilians-Universität München, 80539 Munich, Germany;
| | - Thomas Fenzl
- Clinic for Anesthesiology and Intensive Care, TUM School of Medicine, Technical University of Munich, 81675 Munich, Germany; (S.K.); (M.A.); (T.F.)
| | - Benjamin Schusser
- Reproductive Biotechnology, TUM School of Life Sciences, Technical University of Munich, 85354 Freising, Germany;
| | - Christine Baumgartner
- Center for Preclinical Research, TUM School of Medicine, Technical University of Munich, 81675 Munich, Germany; (L.W.); (A.M.S.); (J.W.); (S.C.S.); (J.R.)
- Veterinary Faculty, Ludwig-Maximilians-Universität München, 80539 Munich, Germany
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3
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Hilgart DR, Iversen MM, Peters AY, Zabriskie MS, Hoareau GL, Vapniarsky N, Clark GA, Shah LM, Rieke V. Non-invasive central nervous system assessment of a porcine model of neuropathic pain demonstrates increased latency of somatosensory-evoked potentials. J Neurosci Methods 2023; 396:109934. [PMID: 37524248 PMCID: PMC10530261 DOI: 10.1016/j.jneumeth.2023.109934] [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: 05/18/2023] [Revised: 07/01/2023] [Accepted: 07/28/2023] [Indexed: 08/02/2023]
Abstract
BACKGROUND The study of chronic pain and its treatments requires a robust animal model with objective and quantifiable metrics. Porcine neuropathic pain models have been assessed with peripheral pain recordings and behavioral responses, but thus far central nervous system electrophysiology has not been investigated. This work aimed to record non-invasive, somatosensory-evoked potentials (SEPs) via electroencephalography in order to quantitatively assess chronic neuropathic pain induced in a porcine model. NEW METHOD Peripheral neuritis trauma (PNT) was induced unilaterally in the common peroneal nerve of domestic farm pigs, with the contralateral leg serving as the control for each animal. SEPs were generated by stimulation of the peripheral nerves distal to the PNT and were recorded non-invasively using transcranial electroencephalography (EEG). The P30 wave of the SEP was analyzed for latency changes. RESULTS P30 SEPs were successfully recorded with non-invasive EEG. PNT resulted in significantly longer P30 SEP latencies (p < 0.01 [n = 8]) with a median latency increase of 14.3 [IQR 5.0 - 17.5] ms. Histological results confirmed perineural inflammatory response and nerve damage around the PNT nerves. COMPARISON WITH EXISTING METHOD(S) Control P30 SEPs were similar in latency and amplitude to those previously recorded invasively in healthy pigs. Non-invasive recordings have numerous advantages over invasive measures. CONCLUSIONS P30 SEP latency can serve as a quantifiable neurological measure that reflects central nervous system processing in a porcine model of chronic pain. Advancing the development of a porcine chronic pain model will facilitate the translation of experimental therapies into human clinical trials.
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Affiliation(s)
- David R Hilgart
- Department of Biomedical Engineering, University of Utah, Salt Lake City, UT, USA
| | - Marta M Iversen
- Department of Physical Medicine and Rehabilitation, University of Utah, Salt Lake City, UT, USA
| | - Angela Y Peters
- Department of Neurology, University of Utah, Salt Lake City, UT, USA
| | - Matthew S Zabriskie
- Department of Radiology and Imaging Sciences, University of Utah, Salt Lake City, UT, USA
| | - Guillaume L Hoareau
- Department of Emergency Medicine, University of Utah, Salt Lake City, UT, USA
| | - Natalia Vapniarsky
- Department of Pathology Microbiology and Immunology, University of California Davis, Davis, CA, USA
| | - Gregory A Clark
- Department of Biomedical Engineering, University of Utah, Salt Lake City, UT, USA
| | - Lubdha M Shah
- Department of Radiology and Imaging Sciences, University of Utah, Salt Lake City, UT, USA
| | - Viola Rieke
- Department of Radiology and Imaging Sciences, University of Utah, Salt Lake City, UT, USA.
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4
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Mirra A, Gamez Maidanskaia E, Carmo LP, Levionnois O, Spadavecchia C. How is depth of anaesthesia assessed in experimental pigs? A scoping review. PLoS One 2023; 18:e0283511. [PMID: 36952576 PMCID: PMC10035875 DOI: 10.1371/journal.pone.0283511] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2022] [Accepted: 03/09/2023] [Indexed: 03/25/2023] Open
Abstract
BACKGROUND Despite the large number of pigs involved in translational studies, no gold standard depth of anaesthesia indicators are available. We undertook a scoping review to investigate and summarize the evidence that sustains or contradicts the use of depth of anaesthesia indicators in this species. METHODS Medline, Embase and CAB abstract were searched up to September 22nd 2022. No limits were set for time, language and study type. Only original articles of in vivo studies using pigs or minipigs undergoing general anaesthesia were included. The depth of anaesthesia indicators reported in the selected papers were divided in two categories: A, indicators purposely investigated as method to assess depth of anaesthesia; B, indicators reported but not investigated as method to assess depth of anaesthesia. RESULTS Out of 13792 papers found, 105 were included after the screening process. Category A: 17 depth of anaesthesia indicators were found in 19 papers. Studies were conducted using inhalant anaesthetics as the main anaesthetic agent in the majority of the cases (13/19 = 68.4%), while 3/19 (15.8%) used propofol. The most investigated depth of anaesthesia indicators were bispectral index (8/19 = 42.1%) and spectral edge frequency 95% (5/19 = 26.3%). Contrasting results about the specific usefulness of each depth of anaesthesia indicators were reported. Category B: 23 depth of anaesthesia indicators were found in 92 papers. The most reported depth of anaesthesia indicators were: motor response following a stimulus (37/92 = 40.2%), depth of anaesthesia scores (21/92 = 23.3%), bispectral index (16/92 = 17.8%) and spectral edge frequency 95% (9/92 = 9.8%). CONCLUSION Results highlight the lack of scientifically valid and reliable indicators to ensure adequate depth of anaesthesia in pigs.
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Affiliation(s)
- Alessandro Mirra
- Anaesthesiology and Pain Therapy Section, Department of Clinical Veterinary Medicine, Vetsuisse Faculty, University of Bern, Bern, Switzerland
- Graduate School for Cellular and Biomedical Sciences, University of Bern, Bern, Switzerland
| | - Ekaterina Gamez Maidanskaia
- Anaesthesiology and Pain Therapy Section, Department of Clinical Veterinary Medicine, Vetsuisse Faculty, University of Bern, Bern, Switzerland
| | - Luís Pedro Carmo
- Department of Clinical Research und Public Health (DCR-VPH), Vetsuisse Faculty, Veterinary Public Health Institute, University of Bern, Bern, Switzerland
- Norwegian Veterinary Institute, Ås, Norway
| | - Olivier Levionnois
- Anaesthesiology and Pain Therapy Section, Department of Clinical Veterinary Medicine, Vetsuisse Faculty, University of Bern, Bern, Switzerland
| | - Claudia Spadavecchia
- Anaesthesiology and Pain Therapy Section, Department of Clinical Veterinary Medicine, Vetsuisse Faculty, University of Bern, Bern, Switzerland
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Söbbeler FJ, Wendt S, Briese A, Tünsmeier J, Waldmann KH, Kästner SBR, von Altrock A. Comparative Study of Pain-Related Responses of Male Piglets up to Seven Days of Age to the Application of Different Local Anaesthetics and Subsequent Castration. Animals (Basel) 2022; 12:ani12202833. [PMID: 36290223 PMCID: PMC9597853 DOI: 10.3390/ani12202833] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2022] [Revised: 10/10/2022] [Accepted: 10/14/2022] [Indexed: 11/25/2022] Open
Abstract
Simple Summary Since 2021, surgical piglet castration must be performed with complete pain elimination according to the Animal Protection Law in Germany. General anaesthesia by isoflurane inhalation, which can be performed by the farmer, or by injection of ketamine and azaperone, which must be performed by a veterinarian, are the options available. At present, local anaesthesia is still under debate because of the lack of proof of complete pain elimination and the pain on injection. We tested three local anaesthetics (procaine, lidocaine, and mepivacaine) at two different doses each. Because pain responses can be masked by reactions caused by handling, the piglets were given superficial isoflurane anaesthesia. The pain on injection to the testes was compared with intramuscular injection, and the effectiveness during castration was compared among the local anaesthetics. Nocifensive movements, respiratory rate, blood pressure, heart rate and its variability as well as electroencephalography (EEG) changes were studied in relation to the painful interventions. Most indicators of nociception point to testicular injection pain being beyond intramuscular injection pain when an effective amount of local anaesthetic was used. However, complete pain elimination could not be achieved during castration under local anaesthesia. Abstract To evaluate pain responses to intratesticular and subscrotal injection of three local anaesthetics and their efficacy during castration a randomized controlled study was conducted. In groups of 20 piglets, procaine (2%), lidocaine (2%), or mepivacaine (2%) were administered subscrotal and intratesticularly in two different dosages: 0.5 mL of the original substances or the maximum recommended dosage according to body weight diluted with isotonic saline to a volume of 0.3 mL per each injection site. Two placebo groups received the equivalent volume of isotonic saline. A control group was injected intramuscularly with 0.5 mL isotonic saline for injection pain comparison. Electroencephalographic changes, respiratory rate, heart rate and its variability, blood pressure, and nocifensive movements were assessed in superficial isoflurane anaesthesia. While EEG-changes and linear measures of heart rate variability did not appear conclusive, the low frequency/high frequency (LF/HF) ratio corresponded best with the other pain indicators recorded. The injection of 0.3 mL diluted local anaesthetic per injection site elicited significant fewer signs of pain compared to intramuscular injection of saline. However, pain reduction, but not complete pain elimination, during castration could only be achieved with 0.5 mL of the 2% local anaesthetics per injection site, whereby lidocaine and mepivacaine were the most effective.
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Affiliation(s)
- Franz Josef Söbbeler
- Clinic for Small Animals, University of Veterinary Medicine Hannover, Hannover, Foundation, 30559 Hannover, Germany
- Correspondence: (F.J.S.); (A.v.A.)
| | - Sören Wendt
- Clinic for Swine, Small Ruminants, Forensic Medicine and Ambulatory Service, University of Veterinary Medicine Hannover, Foundation, 30173 Hannover, Germany
| | | | - Julia Tünsmeier
- Clinic for Small Animals, University of Veterinary Medicine Hannover, Hannover, Foundation, 30559 Hannover, Germany
| | - Karl-Heinz Waldmann
- Clinic for Swine, Small Ruminants, Forensic Medicine and Ambulatory Service, University of Veterinary Medicine Hannover, Foundation, 30173 Hannover, Germany
| | - Sabine Beate Rita Kästner
- Clinic for Small Animals, University of Veterinary Medicine Hannover, Hannover, Foundation, 30559 Hannover, Germany
| | - Alexandra von Altrock
- Clinic for Swine, Small Ruminants, Forensic Medicine and Ambulatory Service, University of Veterinary Medicine Hannover, Foundation, 30173 Hannover, Germany
- Correspondence: (F.J.S.); (A.v.A.)
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6
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Mirra A, Spadavecchia C, Levionnois O. Correlation of Sedline-generated variables and clinical signs with anaesthetic depth in experimental pigs receiving propofol. PLoS One 2022; 17:e0275484. [PMID: 36174080 PMCID: PMC9522294 DOI: 10.1371/journal.pone.0275484] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2022] [Accepted: 09/16/2022] [Indexed: 11/19/2022] Open
Abstract
Most of currently available electroencephalographic (EEG)-based tools to assess depth of anaesthesia have not been studied or have been judged unreliable in pigs. Our primary aim was to investigate the dose-effect relationship between increasing propofol dose and variables generated by the EEG-based depth of anaesthesia monitor Sedline in pigs. A secondary aim was to compare the anaesthetic doses with clinical outcomes commonly used to assess depth of anaesthesia in this species. Sixteen juvenile pigs were included. Propofol infusion was administered at 10 mg kg-1 h-1, increased by 10 mg kg-1 h-1 every 15 minutes, and stopped when an EEG Suppression ratio >80% was reached. Patient state index, suppression ratio, left and right spectral edge frequency 95%, and outcomes from commonly used clinical methods to assess depth of anaesthesia in pigs were recorded. The best pharmacodynamic model was assessed for Patient state index, suppression ratio, left and right spectral edge frequency 95% in response to propofol administration. The decrease of Patient state index best fitted to an inhibitory double-sigmoid model (including a plateau phase). The increase of suppression ratio fitted a typical sigmoid Emax model. No relevant relationship could be identified between spectral edge frequency 95% values and propofol administration. A large variability in clinical outcomes was observed among pigs, such that they did not provide a reliable evaluation of propofol dose. The relationship between propofol dose and Patient state index/suppression ratio described in the present study can be used for prediction in future investigations. The evaluation of depth of anaesthesia based on common clinical outcomes was not reliable.
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Affiliation(s)
- Alessandro Mirra
- Section of Anaesthesiology and Pain Therapy, Department of Clinical Veterinary Medicine, Vetsuisse Faculty, University of Bern, Bern, Switzerland
- Graduate School for Cellular and Biomedical Sciences, University of Bern, Bern, Switzerland
| | - Claudia Spadavecchia
- Section of Anaesthesiology and Pain Therapy, Department of Clinical Veterinary Medicine, Vetsuisse Faculty, University of Bern, Bern, Switzerland
| | - Olivier Levionnois
- Section of Anaesthesiology and Pain Therapy, Department of Clinical Veterinary Medicine, Vetsuisse Faculty, University of Bern, Bern, Switzerland
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7
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Nociception-Induced Changes in Electroencephalographic Activity and FOS Protein Expression in Piglets Undergoing Castration under Isoflurane Anaesthesia. Animals (Basel) 2022; 12:ani12182309. [PMID: 36139169 PMCID: PMC9494976 DOI: 10.3390/ani12182309] [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: 08/09/2022] [Accepted: 08/31/2022] [Indexed: 11/16/2022] Open
Abstract
The objective of this study was to investigate the electroencephalographic reaction pattern and FOS protein expression in male piglets undergoing surgical castration under light isoflurane anaesthesia with or without local anaesthesia. The experiment was conducted under isoflurane anaesthesia to exclude the effect of the affective components of pain on the measurements. Changes in the oscillatory activity of the cerebral cortex over a 90 s period after noxious stimulation or simulated interventions were analysed. FOS expression was determined postmortem by performing immunohistochemistry in the dorsal horn of the spinal cord. The analysis of the response to an interdigital pinch revealed a biphasic reaction pattern in the electroencephalogram (EEG) that similarly was observed for the surgical stimuli during the castration procedure in the group without analgesia. This EEG response was attenuated or altered by the application of local anaesthetics. Immunohistochemical staining for FOS indicated a lower expression in the handling and in three local anaesthetic groups than in the animals castrated without pain relief. The findings indicate that EEG and FOS expression may serve as indicators for nociception in piglets under light isoflurane anaesthesia. A lower activation of nociceptive pathways occurs during castration after the application of local anaesthetics. However, EEG and FOS analyses should be combined with additional parameters to assess nociception, e.g., haemodynamic monitoring.
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8
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Werner J, Saller AM, Reiser J, Senf S, Deffner P, Abendschön N, Fischer J, Grott A, Miller R, Zablotski Y, Steiger K, Bergmann S, Erhard MH, Ritzmann M, Zöls S, Baumgartner C. Evaluation of Two Injection Techniques in Combination with the Local Anesthetics Lidocaine and Mepivacaine for Piglets Undergoing Surgical Castration. Animals (Basel) 2022; 12:1028. [PMID: 35454274 PMCID: PMC9029161 DOI: 10.3390/ani12081028] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2022] [Revised: 04/08/2022] [Accepted: 04/12/2022] [Indexed: 02/06/2023] Open
Abstract
The present study evaluated the effects of two injection techniques in combination with lidocaine or mepivacaine for piglets undergoing castration. To improve ease of use, a cannula with side holes (one-step fenestrated (F)) was invented to simultaneously deliver a local anesthetic into the testis and scrotum and was compared to a two-step injection technique. The distribution of a lidocaine/contrast agent mixture using the two methods was examined using computed tomography. Piglets were randomly divided into treatment groups: handling, castration without pain relief and castration after lidocaine or mepivacaine injection using the one-step F or two-step method. Acute physiological responses to noxious stimuli were evaluated by measuring the mean arterial blood pressure (MAP), heart rate (HR) and nocifensive movements. Fos protein expression in the spinal dorsal cord was semi-quantitatively analyzed. Both injection techniques achieved similar distribution patterns. The one-step F method was faster and easier. Injection was not associated with significant changes in MAP or HR, but Mepi1 and NaCl elicited significantly increased nocifensive movements. Both techniques significantly reduced MAP and nocifensive movements when the spermatic cords were cut, regardless of the local anesthetic type. Compared to NaCl, only the lidocaine treatments significantly reduced HR during skin incision. Lido2 significantly reduced Fos protein expression.
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Affiliation(s)
- Julia Werner
- Center of Preclinical Research, Technical University of Munich, 81675 Munich, Germany
| | - Anna M Saller
- Center of Preclinical Research, Technical University of Munich, 81675 Munich, Germany
| | - Judith Reiser
- Center of Preclinical Research, Technical University of Munich, 81675 Munich, Germany
| | - Steffanie Senf
- Clinic for Swine, Center for Clinical Veterinary Medicine, LMU Munich, 85764 Oberschleissheim, Germany
| | - Pauline Deffner
- Clinic for Swine, Center for Clinical Veterinary Medicine, LMU Munich, 85764 Oberschleissheim, Germany
| | - Nora Abendschön
- Clinic for Swine, Center for Clinical Veterinary Medicine, LMU Munich, 85764 Oberschleissheim, Germany
| | - Johannes Fischer
- Center of Preclinical Research, Technical University of Munich, 81675 Munich, Germany
| | - Andrea Grott
- Chair of Animal Welfare, Ethology, Animal Hygiene and Husbandry, LMU Munich, 80539 Munich, Germany
| | - Regina Miller
- Chair of Animal Welfare, Ethology, Animal Hygiene and Husbandry, LMU Munich, 80539 Munich, Germany
| | - Yury Zablotski
- Clinic for Swine, Center for Clinical Veterinary Medicine, LMU Munich, 85764 Oberschleissheim, Germany
| | - Katja Steiger
- Institute of Pathology, School of Medicine, Technical University of Munich, 81675 Munich, Germany
| | - Shana Bergmann
- Chair of Animal Welfare, Ethology, Animal Hygiene and Husbandry, LMU Munich, 80539 Munich, Germany
| | - Michael H Erhard
- Chair of Animal Welfare, Ethology, Animal Hygiene and Husbandry, LMU Munich, 80539 Munich, Germany
| | - Mathias Ritzmann
- Clinic for Swine, Center for Clinical Veterinary Medicine, LMU Munich, 85764 Oberschleissheim, Germany
| | - Susanne Zöls
- Clinic for Swine, Center for Clinical Veterinary Medicine, LMU Munich, 85764 Oberschleissheim, Germany
| | - Christine Baumgartner
- Center of Preclinical Research, Technical University of Munich, 81675 Munich, Germany
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9
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A systematic review of porcine models in translational pain research. Lab Anim (NY) 2021; 50:313-326. [PMID: 34650279 DOI: 10.1038/s41684-021-00862-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2020] [Accepted: 08/27/2021] [Indexed: 11/09/2022]
Abstract
Translating basic pain research from rodents to humans has proven to be a challenging task. Efforts have been made to develop preclinical large animal models of pain, such as the pig. However, no consistent overview and comparison of pig models of pain are currently available. Therefore, in this review, our primary aim was to identify the available pig models in pain research and compare these models in terms of intensity and duration. First, we systematically searched Proquest, Scopus and Web of Science and compared the duration for which the pigs were significantly sensitized as well as the intensity of mechanical sensitization. We searched models within the specific field of pain and adjacent fields in which pain induction or assessment is relevant, such as pig production. Second, we compared assessment methodologies in surrogate pain models in humans and pigs to identify areas of overlap and possible improvement. Based on the literature search, 23 types of porcine pain models were identified; 13 of which could be compared quantitatively. The induced sensitization lasted from hours to months and intensities ranged from insignificant to the maximum attainable. We also found a near to complete overlap of assessment methodologies between human and pig models within the area of peripheral neurophysiology, which allows for direct comparison of results obtained in the two species. In spite of this overlap, further development of pain assessment methodologies is still needed. We suggest that central nervous system electrophysiology, such as electroencephalography, electrocorticography or intracortical recordings, may pave the way for future objective pain assessment.
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10
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Saller AM, Werner J, Reiser J, Senf S, Deffner P, Abendschön N, Weiß C, Fischer J, Schörwerth A, Miller R, Zablotski Y, Bergmann S, Erhard MH, Ritzmann M, Zöls S, Baumgartner C. Local anesthesia in piglets undergoing castration-A comparative study to investigate the analgesic effects of four local anesthetics on the basis of acute physiological responses and limb movements. PLoS One 2020; 15:e0236742. [PMID: 32730302 PMCID: PMC7392247 DOI: 10.1371/journal.pone.0236742] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Accepted: 07/13/2020] [Indexed: 01/07/2023] Open
Abstract
Surgical castration of male piglets without analgesia is a painful procedure. This prospective, randomized and double-blinded study aimed to evaluate the analgesic effects of four different local anesthetics for piglet castration during the first week of life. In total, 54 piglets aged 3 to 7 days were distributed into 6 treatment groups: handling (H); castration without pain relief (sodium chloride, NaCl); and castration with a local anesthetic: 4% procaine (P), 2% lidocaine (L), 0.5% bupivacaine (B) or 20 mg/ml mepivacaine (M). By excluding stress and fear as disruptive factors via a minimum anesthesia model, all piglets received individual minimum alveolar concentration (MAC) isoflurane anesthesia. Twenty minutes before castration, all treatment groups except group H received one injection per testis. Then, 0.5 ml of a local anesthetic or NaCl was injected intratesticularly (i.t.), and 0.5 ml was administered subscrotally. Acute physiological responses to noxious stimuli at injection and castration were evaluated by measuring blood pressure (BP), heart rate (HR), cortisol, epinephrine, norepinephrine and chromogranin A (CgA); limb movements were quantified. The results confirm that castration without analgesia is highly painful. Surgical castration without pain relief revealed significant changes in mean arterial blood pressure (MAP) and HR. Local anesthetic administration significantly reduced changes in BP and HR associated with castration. Piglets receiving a preoperative local anesthetic exhibited the fewest limb movements during castration, while the NaCl group exhibited the most. Injection itself was not associated with significant changes in MAP or HR. However, many piglets exhibited limb movements during injection, indicating that the injection itself causes nociceptive pain. No significant differences were found between groups regarding parameters of plasma cortisol, catecholamines and CgA. In conclusion, all four local anesthetics administered are highly effective at reducing signs of nociception during castration under light isoflurane anesthesia. However, injection of a local anesthetic seems to be painful.
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Affiliation(s)
- Anna M. Saller
- Center of Preclinical Research, Technical University of Munich, Bavaria, Germany
| | - Julia Werner
- Center of Preclinical Research, Technical University of Munich, Bavaria, Germany
| | - Judith Reiser
- Center of Preclinical Research, Technical University of Munich, Bavaria, Germany
| | - Steffanie Senf
- Clinic for Swine, Center for Clinical Veterinary Medicine, LMU Munich, Bavaria, Germany
| | - Pauline Deffner
- Clinic for Swine, Center for Clinical Veterinary Medicine, LMU Munich, Bavaria, Germany
| | - Nora Abendschön
- Clinic for Swine, Center for Clinical Veterinary Medicine, LMU Munich, Bavaria, Germany
| | - Christine Weiß
- Clinic for Swine, Center for Clinical Veterinary Medicine, LMU Munich, Bavaria, Germany
| | - Johannes Fischer
- Center of Preclinical Research, Technical University of Munich, Bavaria, Germany
| | - Andrea Schörwerth
- Chair of Animal Welfare, Ethology, Animal Hygiene and Husbandry, LMU Munich, Bavaria, Germany
| | - Regina Miller
- Chair of Animal Welfare, Ethology, Animal Hygiene and Husbandry, LMU Munich, Bavaria, Germany
| | - Yury Zablotski
- Clinic for Swine, Center for Clinical Veterinary Medicine, LMU Munich, Bavaria, Germany
| | - Shana Bergmann
- Chair of Animal Welfare, Ethology, Animal Hygiene and Husbandry, LMU Munich, Bavaria, Germany
| | - Michael H. Erhard
- Chair of Animal Welfare, Ethology, Animal Hygiene and Husbandry, LMU Munich, Bavaria, Germany
| | - Mathias Ritzmann
- Clinic for Swine, Center for Clinical Veterinary Medicine, LMU Munich, Bavaria, Germany
| | - Susanne Zöls
- Clinic for Swine, Center for Clinical Veterinary Medicine, LMU Munich, Bavaria, Germany
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Morelli J, Briganti A, Fuchs B, Huber Ð, Evans AL, Reljić S, Arnemo JM. Comparison of two non-invasive arterial blood pressure monitoring techniques in brown bears ( Ursus arctos). Vet Anim Sci 2020; 9:100094. [PMID: 32734104 PMCID: PMC7386746 DOI: 10.1016/j.vas.2020.100094] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2019] [Revised: 01/11/2020] [Accepted: 01/15/2020] [Indexed: 11/25/2022] Open
Abstract
Monitoring arterial blood pressure (BP), represents a more accurate evaluation of hemodynamics than heart rate alone and is essential for preventing and treating intra- and post-operative complications in wildlife chemical immobilization. The objectives of the study were to test the correlation between standard oscillometry and Korotkoff's technique in anesthetized free-ranging brown bears in Croatia and Scandinavia and to assess the blood pressure in both locations. Five bears were snared and darted with xylazine and ketamine in Croatia, and 20 bears were darted from a helicopter with medetomidine and tiletamine-zolazepam in Scandinavia. Blood pressure was simultaneously measured with both techniques every 5 minutes. Correlation between techniques, trends of BP variation, and the factors of the capture which likely influenced BP were assessed. Successful measurements of BP were achieved in 93% of all attempts with the Korotkoff's technique but in only 29% of all attempts with oscillometry. The latter method mostly provided lower values of BP compared to Korotkoff's technique in yearlings. Most bears showed a decreasing trend in systolic and mean BP over time, consistent between the two techniques. All bears were hypertensive: the auscultatory technique detected moderate to severe systolic hypertension in 25% and 84% of bears in Croatia and in Scandinavia, respectively, with significantly higher BP in subadults and adults compared to yearlings. Only Korotkoff's method resulted in a reliable and effective tool for BP assessment in brown bears. The anesthetic protocols used in the present study in association with the capture methods produced hypertension in all animals.
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Key Words
- BP, blood pressure
- Blood pressure
- Brown bear
- CW/LC, cuff width/limb circumference
- DAP, diastolic arterial blood pressure
- GPS, Global Positioning System
- HR, heart rate
- Hypertension
- IM, intramuscularly
- Korotkoff
- LoA, limit of agreement
- MAP, mean arterial blood pressure
- MZT, medetomidine-zolazepam-tiletamine
- Oscillometry
- SAP, systolic arterial blood pressure
- SD, Standard Deviation
- SpO2, hemoglobin-oxygen saturation
- Sphygmomanometer
- VHF, Very High Frequency
- XK, xylazine-ketamine
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Affiliation(s)
- Jacopo Morelli
- Department of Forestry and Wildlife Management, Inland Norway University of Applied Sciences, Anne Evenstadvegen 80, 2480 Koppang, Norway
| | - Angela Briganti
- Department of Veterinary Sciences University of Pisa, Via Livornese, 56122 San Piero A Grado, Italy
| | - Boris Fuchs
- Department of Forestry and Wildlife Management, Inland Norway University of Applied Sciences, Anne Evenstadvegen 80, 2480 Koppang, Norway
| | - Ðuro Huber
- Department of Biology, Faculty of Veterinary Medicine, University of Zagreb, Heinzelova ul. 55, 10000 Zagreb, Croatia
| | - Alina L Evans
- Department of Forestry and Wildlife Management, Inland Norway University of Applied Sciences, Anne Evenstadvegen 80, 2480 Koppang, Norway
| | - Slaven Reljić
- Department of Biology, Faculty of Veterinary Medicine, University of Zagreb, Heinzelova ul. 55, 10000 Zagreb, Croatia
| | - Jon M Arnemo
- Department of Forestry and Wildlife Management, Inland Norway University of Applied Sciences, Anne Evenstadvegen 80, 2480 Koppang, Norway.,Department of Wildlife, Fish and Environmental Studies, Swedish University of Agricultural Sciences, Skogsmarksgränd 17, 901 83 Umeå, Sweden
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12
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Ruíz-López P, Domínguez JM, Granados MDM. Intraoperative nociception-antinociception monitors: A review from the veterinary perspective. Vet Anaesth Analg 2019; 47:152-159. [PMID: 32007442 DOI: 10.1016/j.vaa.2019.09.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2019] [Revised: 08/12/2019] [Accepted: 09/24/2019] [Indexed: 12/26/2022]
Abstract
OBJECTIVE To review monitors currently available for the assessment of nociception-antinociception in veterinary medicine. DATABASES USED PubMed, Web of Science and Google Scholar. The results were initially filtered manually based on the title and the abstract. CONCLUSIONS The provision of adequate antinociception is difficult to achieve in veterinary anaesthesia. Currently, heart rate and arterial blood pressure are used to monitor the response to a noxious stimulus during anaesthesia, with minimum alveolar concentration-sparing effect and stress-related hormones used for this purpose in research studies. However, since none of these variables truly assess intraoperative nociception, several alternative monitoring devices have been developed for use in humans. These nociceptive-antinociceptive monitoring systems derive information from variables, such as electroencephalography, parasympathetic nervous system (PNS) response, sympathetic nervous system response and electromyography. Several of these monitoring systems have been investigated in veterinary medicine, although few have been used to assess intraoperative nociception in animals. There is controversy regarding their effectiveness and clinical use in animals. A nociceptive-antinociceptive monitoring system based on the PNS response has been developed for use in cats, dogs and horses. It uses the parasympathetic tone activity index, which is believed to detect inadequate intraoperative nociception-antinociception balance in veterinary anaesthesia. Nonetheless, there are limited published studies to date, and cardiovascular variables remain the gold standard. Consequently, further studies in this area are warranted.
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Affiliation(s)
- Patricia Ruíz-López
- Anaesthesiology Unit, Animal Medicine and Surgery Department, Faculty of Veterinary Medicine, University of Córdoba, Córdoba, Spain.
| | - Juan Manuel Domínguez
- Anaesthesiology Unit, Animal Medicine and Surgery Department, Faculty of Veterinary Medicine, University of Córdoba, Córdoba, Spain
| | - María Del Mar Granados
- Anaesthesiology Unit, Animal Medicine and Surgery Department, Faculty of Veterinary Medicine, University of Córdoba, Córdoba, Spain
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Erickson RL, Blevins CE, Souza Dyer CD, Marx JO. Alfaxalone-Xylazine Anesthesia in Laboratory Mice ( Mus musculus). JOURNAL OF THE AMERICAN ASSOCIATION FOR LABORATORY ANIMAL SCIENCE 2018; 58:30-39. [PMID: 30572981 DOI: 10.30802/aalas-jaalas-18-000010] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Since its recent reformulation, alfaxalone has gained popularity as an injectable veterinary anesthetic, including promising studies demonstrating the use of alfaxalone-xylazine for anesthesia in mice. Here we sought to expand these studies by testing additional dose ranges, elaborating on physiologic monitoring, testing sex- and strain-associated differences, and evaluating efficacy during actual surgical conditions. C57BL/6J mice showed significant sex-associated differences in anesthetic sensitivity, with males requiring higher doses of alfaxalone (80-120 mg/kg IP alfaxalone with 10 mg/kg IP xylazine) than females (40-80 mg/kg IP alfaxalone with 10 mg/kg IP xylazine) to achieve a surgical plane of anesthesia. In addition, female outbred CD1 mice were less sensitive to alfaxalone than female inbred C57BL/6J mice. When used during actual surgery, alfaxalone-xylazine administered intraperitoneally provided adequate anesthesia for a model of orthopedic surgery, whereas the same anesthetic regimen during laparotomy resulted in unacceptably high mortality; survival during laparotomy increased when drugs were administered subcutaneously. These results indicate that alfaxalone-xylazine may be a viable option for injectable surgical anesthesia in mice, although strain- and sex-associated differences and alternative routes of administration should be considered when optimizing the anesthetic regimen for specific experimental conditions.
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Affiliation(s)
- Rebecca L Erickson
- Center for Comparative Medicine, Northwestern University, Chicago, Illinois
| | | | - Cecilia De Souza Dyer
- Gene Therapy Program, Department of Medicine, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania
| | - James O Marx
- University Laboratory Animal Resources, University of Pennsylvania, Philadelphia, Pennsylvania, Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, Pennsylvania;,
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Clutton RE. A review of factors affecting analgesic selection in large animals undergoing translational research. Vet J 2018; 236:12-22. [PMID: 29871744 DOI: 10.1016/j.tvjl.2018.04.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2017] [Revised: 04/03/2018] [Accepted: 04/10/2018] [Indexed: 11/29/2022]
Abstract
The widespread physiological effects of pain in experimental animals are likely to reduce the validity of data except when pain itself is studied. Appropriately prescribed analgesics will limit pain and improve the welfare of animals undergoing noxious experimental procedures. However, their injudicious use may also introduce variability in data and limit study reproducibility. Optimizing both animal welfare and the value of scientific data from experimental studies requires the ability to identify, quantify and treat animal pain by applying a knowledge of analgesic pharmacology that is sympathetic to study objectives. This review first examines the reasons for promoting analgesic use in translational animal research and, in focussing on pigs and small ruminants, then identifies factors that should be considered when devising analgesic plans.
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Affiliation(s)
- R E Clutton
- The Wellcome Trust Critical Care Laboratory for Large Animals, Roslin Institute, Easter Bush Veterinary Centre, Roslin, Midlothian EH25 9RG, United Kingdom.
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15
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Ison SH, Clutton RE, Di Giminiani P, Rutherford KMD. A Review of Pain Assessment in Pigs. Front Vet Sci 2016; 3:108. [PMID: 27965968 PMCID: PMC5124671 DOI: 10.3389/fvets.2016.00108] [Citation(s) in RCA: 69] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2016] [Accepted: 11/15/2016] [Indexed: 11/13/2022] Open
Abstract
There is a moral obligation to minimize pain in pigs used for human benefit. In livestock production, pigs experience pain caused by management procedures, e.g., castration and tail docking, injuries from fighting or poor housing conditions, “management diseases” like mastitis or streptococcal meningitis, and at parturition. Pigs used in biomedical research undergo procedures that are regarded as painful in humans, but do not receive similar levels of analgesia, and pet pigs also experience potentially painful conditions. In all contexts, accurate pain assessment is a prerequisite in (a) the estimation of the welfare consequences of noxious interventions and (b) the development of more effective pain mitigation strategies. This narrative review identifies the sources of pain in pigs, discusses the various assessment measures currently available, and proposes directions for future investigation.
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Affiliation(s)
- Sarah H Ison
- Animal Behaviour and Welfare, Animal and Veterinary Sciences, Scotland's Rural College (SRUC), Edinburgh, UK; Easter Bush Veterinary Centre, Royal (Dick) School of Veterinary Studies, The University of Edinburgh, Midlothian, UK
| | - R Eddie Clutton
- Easter Bush Veterinary Centre, Royal (Dick) School of Veterinary Studies, The University of Edinburgh , Midlothian , UK
| | - Pierpaolo Di Giminiani
- Food and Rural Development, School of Agriculture, Newcastle University , Newcastle upon Tyne , UK
| | - Kenneth M D Rutherford
- Animal Behaviour and Welfare, Animal and Veterinary Sciences, Scotland's Rural College (SRUC) , Edinburgh , UK
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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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17
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Bradbury AG, Clutton RE. Are neuromuscular blocking agents being misused in laboratory pigs? Br J Anaesth 2016; 116:476-85. [PMID: 26934943 DOI: 10.1093/bja/aew019] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The literature (2012-4) describing experimental pig surgery was reviewed to estimate the extent to which neuromuscular block (NMB) is used, to examine methods for ensuring unconsciousness, and to identify the rationale for use of NMB and establish the anaesthetist's training. In the first stage of a two-stage review, NMB use was estimated using Web of Knowledge to identify articles describing NMB during pig surgeries. In the second stage, PubMed and Google Scholar were used to increase the number of articles for determining measures taken to prevent accidental awareness during general anaesthesia (AAGA). The corresponding authors of screened articles were emailed four times to establish the reason for using NMB and the anaesthetists' backgrounds (medical, veterinary, or technical). The first search revealed NMB use in 80 of 411 (20%) studies. Of the 153 articles analysed in the second stage, two described strategies to reduce AAGA. Some (6%) papers did not provide information on anaesthetic doses; citations supporting anaesthetic efficacy were found in only 13. Five of 69 papers using inhalation agents measured end-tidal anaesthetic concentrations based on human, not porcine, minimal alveolar concentrations. The methods in 13% of articles reporting anaesthetic depth assessment were incomplete or questionable, or both; four described using somatic motor reflexes. Corresponding authors of 121 articles reported that the principal reason for NMB was improved 'surgical visualization' (26%). Medical or veterinary anaesthetists supervised anaesthesia in 70% of studies; non-anaesthetists provided NMB, unsupervised, in 23. Nine respondents prioritized experimental expediency over pig welfare. In laboratory pig studies, AAGA may be prevalent; reported details of its attempted prevention are woefully inadequate.
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Affiliation(s)
- A G Bradbury
- Wellcome Trust Critical Care Laboratory for Large Animals, Roslin Institute & Royal (Dick) School of Veterinary Studies, The University of Edinburgh, Roslin, Midlothian EH25 9RG, UK
| | - R E Clutton
- Wellcome Trust Critical Care Laboratory for Large Animals, Roslin Institute & Royal (Dick) School of Veterinary Studies, The University of Edinburgh, Roslin, Midlothian EH25 9RG, UK
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Kaka U, Hui Cheng C, Meng GY, Fakurazi S, Kaka A, Behan AA, Ebrahimi M. Electroencephalographic changes associated with antinociceptive actions of lidocaine, ketamine, meloxicam, and morphine administration in minimally anaesthetized dogs. BIOMED RESEARCH INTERNATIONAL 2015; 2015:305367. [PMID: 25695060 PMCID: PMC4324106 DOI: 10.1155/2015/305367] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/05/2014] [Revised: 11/02/2014] [Accepted: 11/04/2014] [Indexed: 12/24/2022]
Abstract
Effects of ketamine and lidocaine on electroencephalographic (EEG) changes were evaluated in minimally anaesthetized dogs, subjected to electric stimulus. Six dogs were subjected to six treatments in a crossover design with a washout period of one week. Dogs were subjected to intravenous boluses of lidocaine 2 mg/kg, ketamine 3 mg/kg, meloxicam 0.2 mg/kg, morphine 0.2 mg/kg and loading doses of lidocaine 2 mg/kg followed by continuous rate infusion (CRI) of 50 and 100 mcg/kg/min, and ketamine 3 mg/kg followed by CRI of 10 and 50 mcg/kg/min. Electroencephalogram was recorded during electrical stimulation prior to any drug treatment (before treatment) and during electrical stimulation following treatment with the drugs (after treatment) under anaesthesia. Anaesthesia was induced with propofol and maintained with halothane at a stable concentration between 0.85 and 0.95%. Pretreatment median frequency was evidently increased (P < 0.05) for all treatment groups. Lidocaine, ketamine, and morphine depressed the median frequency resulting from the posttreatment stimulation. The depression of median frequency suggested evident antinociceptive effects of these treatments in dogs. It is therefore concluded that lidocaine and ketamine can be used in the analgesic protocol for the postoperative pain management in dogs.
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Affiliation(s)
- Ubedullah Kaka
- Department of Veterinary Clinical Studies, Faculty of Veterinary Medicine, Universiti Putra Malaysia, 43400 Serdang, Selangor, Malaysia
- Faculty of Animal Husbandry & Veterinary Sciences, Sindh Agriculture University Tandojam, Sindh 70060, Pakistan
| | - Chen Hui Cheng
- Department of Veterinary Clinical Studies, Faculty of Veterinary Medicine, Universiti Putra Malaysia, 43400 Serdang, Selangor, Malaysia
| | - Goh Yong Meng
- Department of Veterinary Preclinical Sciences, Faculty of Veterinary Medicine, Universiti Putra Malaysia, 43400 Serdang, Selangor, Malaysia
- Institutes of Tropical Agriculture, Universiti Putra Malaysia, 43400 Serdang, Selangor, Malaysia
| | - Sharida Fakurazi
- Laboratory of Vaccines and Immunotherapeutics, Institute of Bioscience, Universiti Putra Malaysia, 43400 Serdang, Selangor, Malaysia
- Department of Human Anatomy, Faculty of Medicine and Health Science, Universiti Putra Malaysia, 43400 Serdang, Selangor, Malaysia
| | - Asmatullah Kaka
- Department of Veterinary Clinical Studies, Faculty of Veterinary Medicine, Universiti Putra Malaysia, 43400 Serdang, Selangor, Malaysia
- Faculty of Animal Husbandry & Veterinary Sciences, Sindh Agriculture University Tandojam, Sindh 70060, Pakistan
| | - Atique Ahmed Behan
- Faculty of Animal Husbandry & Veterinary Sciences, Sindh Agriculture University Tandojam, Sindh 70060, Pakistan
- Department of Animal Sciences, Faculty of Agriculture, Universiti Putra Malaysia, 43400 Serdang, Selangor, Malaysia
| | - Mahdi Ebrahimi
- Department of Veterinary Preclinical Sciences, Faculty of Veterinary Medicine, Universiti Putra Malaysia, 43400 Serdang, Selangor, Malaysia
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Silva A, Venâncio C, Ortiz AL, Souza AP, Amorim P, Ferreira DA. The effect of high doses of remifentanil in brain near-infrared spectroscopy and in electroencephalographic parameters in pigs. Vet Anaesth Analg 2013; 41:153-62. [PMID: 24119044 DOI: 10.1111/vaa.12091] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2012] [Accepted: 03/20/2013] [Indexed: 11/27/2022]
Abstract
OBJECTIVE To study the effects of a high remifentanil bolus dose on pig's electroencephalographic indices and on brain regional and global oxygenation. STUDY DESIGN Prospective experimental study. ANIMALS Twelve healthy Large-White male pigs, age 3 months and weight 26.2 ± 3.6 kg. METHODS Anaesthesia was induced with intravenous propofol 4 mg kg⁻¹, then maintained with constant rate infusions of propofol (15 mg kg⁻¹ hour⁻¹) and remifentanil (0.3 μg kg⁻¹ minute⁻¹). Following instrumentation, all pigs received a 5 μg kg⁻¹ remifentanil bolus. The responses of jugular venous oxygen saturation, cardiac output and cerebral oxygen saturation to the remifentanil bolus were studied. The Bispectral index, spectral edge frequency 95%, total power, approximate entropy and permutation entropy were also studied. Repeated measures anova and Pearson correlation were used to analyze the effect of remifentanil bolus on these variables until 5 minutes after the bolus. RESULTS Cardiac output and cerebral oxygen saturation decreased significantly after the remifentanil bolus from 4.6 ± 0.9 to 3.8 ± 1.0 L minute⁻¹ and from 65 ± 6 to 62 ± 1% (p < 0.05), respectively. No significant changes were observed in the jugular venous oxygen saturation (p > 0.05) nor in any of the electroencephalogram derived indices (p > 0.05). Correlation analysis revealed strong positive significant correlations between cerebral oxygen saturation and cardiac output (r = 0.82, p < 0.001) and between cerebral oxygen saturation and approximate entropy (r = 0.65, p < 0.001). CONCLUSIONS AND CLINICAL RELEVANCE The effect caused by the remifentanil bolus on the brain oxygenation seems to be better reflected by the cerebral oxygen saturation than the jugular venous oxygen saturation. The effect of remifentanil on the electroencephalogram may not be reflected in indices derived from the electroencephalogram, but the potential of the approximate entropy in reflecting changes caused by opioids on the electroencephalogram should be further investigated.
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Affiliation(s)
- Aura Silva
- Toxicology, REQUIMTE, Faculdade de Farmácia da Universidade do Porto, Porto, Portugal
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20
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Jones A, Bienemann A, Barua N, Murison PJ, Gill S. Anaesthetic complications in pigs undergoing MRI guided convection enhanced drug delivery to the brain: a case series. Vet Anaesth Analg 2012; 39:647-52. [DOI: 10.1111/j.1467-2995.2012.00767.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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21
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Silva A, Antunes L. Electroencephalogram-based anaesthetic depth monitoring in laboratory animals. Lab Anim 2012; 46:85-94. [PMID: 22517991 DOI: 10.1258/la.2012.011135] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Objective measurements of physiological parameters controlled by the autonomic nervous system such as blood pressure, heart rate and respiration are easily obtained nowadays during anaesthesia by the use of monitors: oscillometers, pulseoximeters, electrocardiograms and capnographs are available for laboratory animals. However, the effect-site of hypnotic drugs that cause general anaesthesia is the central nervous system (the brain). In the present, the adjustment of hypnotic drugs in veterinary anaesthesia is performed according to subjective evaluation of clinical signs which are not direct reflexes of anaesthetic effects on the brain, making depth of anaesthesia (DoA) assessment a complicated task. The difficulties in assessing the real anaesthetic state of a laboratory animal may not only result in welfare-threatening situations, such as awareness and pain sensation during surgery, but also in a lack of standardization of experimental conditions, as it is not easy to keep all animals from an experiment in the same DoA without a measure of anaesthetic effect. A direct measure of this dose-effect relationship, although highly necessary, is still missing in the veterinary market. Meanwhile, research has been intense in this subject and methods based on the brain electrical activity (electroencephalogram) have been explored in laboratory animal species. The objective of this review is to explain the achievements made in this topic and clarify how far we are from an objective measure of DoA for animals.
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Affiliation(s)
- Aura Silva
- REQUIMTE, Faculdade de Farmácia da Universidade do Porto, Rua de Jorge Viterbo Ferreira No. 228, 4050-313 Porto, Portugal.
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Kongara K, Chambers JP, Johnson CB. Electroencephalographic responses of tramadol, parecoxib and morphine to acute noxious electrical stimulation in anaesthetised dogs. Res Vet Sci 2010; 88:127-33. [DOI: 10.1016/j.rvsc.2009.05.012] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2008] [Revised: 12/23/2008] [Accepted: 05/12/2009] [Indexed: 11/29/2022]
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23
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Morgaz J, Granados M, Domínguez J, Navarrete R, Galán A, Fernández J, Gómez-Villamandos R. Relationship of bispectral index to hemodynamic variables and alveolar concentration multiples of sevoflurane in puppies. Res Vet Sci 2009; 86:508-13. [DOI: 10.1016/j.rvsc.2008.09.005] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2008] [Revised: 08/05/2008] [Accepted: 09/15/2008] [Indexed: 10/21/2022]
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Martin-Jurado O, Vogt R, Kutter APN, Bettschart-Wolfensberger R, Hatt JM. Effect of inhalation of isoflurane at end-tidal concentrations greater than, equal to, and less than the minimum anesthetic concentration on bispectral index in chickens. Am J Vet Res 2008; 69:1254-61. [PMID: 18828679 DOI: 10.2460/ajvr.69.10.1254] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
OBJECTIVE To determine the effect of inhalation of isoflurane at end-tidal concentrations greater than, equal to, and less than the minimum anesthetic concentration (MAC) on bispectral index (BIS) in chickens. Animals-10 chickens. PROCEDURES For each chicken, the individual MAC of isoflurane was determined by use of the toe-pinch method. After a 1-week interval, chickens were anesthetized with isoflurane at concentrations 1.75, 1.50, 1.25, 1.00, and 0.75 times their individual MAC (administered from higher to lower concentrations). At each MAC multiple, a toe pinch was performed and BIS was assessed and correlated with heart rate, blood pressure, and an awareness score (derived by use of a visual analogue scale). RESULTS Among the chickens, mean +/- SD MAC of isoflurane was 1.15 +/- 0.20%. Burst suppression was detected at every MAC multiple. The BIS and awareness score were correlated directly with each other and changed inversely with increasing isoflurane concentration. Median (range) BIS values during anesthesia at 1.75, 1.50, 1.25, 1.00, and 0.75 MAC of isoflurane were 25 (15 to 35), 35 (25 to 45), 35 (20 to 50), 40 (25 to 55), and 50 (35 to 65), respectively. Median BIS value at extubation was 70 +/- 9. Values of BIS correlated with blood pressure, but not with heart rate. Blood pressure changed with end-tidal isoflurane concentrations, whereas heart rate did not. CONCLUSIONS AND CLINICAL RELEVANCE Assessment of BIS can be used to monitor the electrical activity of the brain and the degree of unconsciousness in chickens during isoflurane anesthesia.
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Affiliation(s)
- Olga Martin-Jurado
- Clinic of Zoo Animals, Exotic Pets and Wildlife, Vetsuisse Faculty, University of Zurich, Winterthurerstr 260, 8057 Switzerland
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Otto KA. EEG power spectrum analysis for monitoring depth of anaesthesia during experimental surgery. Lab Anim 2008; 42:45-61. [PMID: 18348766 DOI: 10.1258/la.2007.006025] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The first attempts to introduce computerized power spectrum analysis of the electroencephalogram (EEG) as an intraoperative anaesthesia monitoring device started approximately 30 years ago. Since that time, the effects of various anaesthetic agents, sedative and analgesic drugs on the EEG pattern have been addressed in numerous studies in human patients and different animal species. These studies revealed dose-dependent changes in the EEG power spectrum for many intravenous and volatile anaesthetics. Moreover, EEG responses evoked by surgical stimuli during relative light levels of surgical anaesthesia have been classified as 'arousal' and 'paradoxical arousal' reaction, previously referred to as 'desynchronization' and 'synchronization', respectively. Contrasting reports on the correlation between quantitative EEG (QEEG) variables derived from power spectrum analysis (i.e. spectral edge frequency, median frequency) and simultaneously recorded clinical signs such as movement and haemodynamic responses, however, limited the routine use of intraoperative EEG monitoring. In addition, the appearance of EEG burst suppression pattern and isoelectricity at clinically relevant concentrations/doses of newer general anaesthetics (i.e. isoflurane, sevoflurane, propofol) may have weakened the dose-related EEG changes previously reported. Despite these findings, the EEG power spectrum analysis may still provide valuable information during intraoperative monitoring in the individual subject. The information obtained from EEG power spectrum analysis may be further supplemented by newer EEG indices such as bispectral index and approximate entropy or other neurophysiological monitors including auditory evoked potentials or somatosensory evoked potentials.
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Affiliation(s)
- Klaus A Otto
- Institut für Versuchstierkunde und Zentrales Tierlaboratorium, Medizinische Hochschule Hannover, Carl-Neuberg-Str. 1, D-30625 Hannover, Germany.
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Otto KA. Effects of averaging data series on the electroencephalographic response to noxious visceral stimulation in isoflurane-anaesthetized dogs. Res Vet Sci 2007; 83:385-93. [PMID: 17368688 DOI: 10.1016/j.rvsc.2007.01.015] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2006] [Revised: 01/03/2007] [Accepted: 01/25/2007] [Indexed: 11/28/2022]
Abstract
The effects of averaging epochs on electroencephalographic (EEG) responses to visceral stimulation has been determined in seven isoflurane-anaesthetized dogs. Quantitative EEG variables including 80% spectral edge frequency (SEF80), median frequency (MF), relative power in the delta, theta, alpha, beta band and power band ratios (theta/delta, alpha/delta, beta/delta) were recorded over 1min before stimulation and during a 1-minute stimulation period. During off-line analysis EEG variables were derived from either single 2-second EEG epochs or as an average from 5, 10, 15 and 30 consecutive 2-second epochs. Noxious stimulation resulted in significant increases in SEF80, MF, alpha power, beta power, alpha/delta ratio and beta/delta ratio. The number of variables that were significantly affected as well as the strength of changes as indicated by p-values, however, varied with the number of epochs subjected to averaging. The data suggest that stimulation-induced EEG changes may be more pronounced at lower rather than at higher averaging rates.
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Affiliation(s)
- Klaus A Otto
- Hannover Medical School, Laboratory Animal Facility, Carl-Neuberg-Str. 1, D-30625 Hannover, Germany.
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Martín-Cancho MF, Lima JR, Luis L, Crisóstomo V, López MA, Ezquerra LJ, Carrasco-Jiménez MS, Usón-Gargallo J. Bispectral index, spectral edge frequency 95% and median frequency recorded at varying desflurane concentrations in pigs. Res Vet Sci 2006; 81:373-81. [PMID: 16516255 DOI: 10.1016/j.rvsc.2006.01.003] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2005] [Revised: 11/25/2005] [Accepted: 01/04/2006] [Indexed: 11/19/2022]
Abstract
The objective of this study is to evaluate the usefulness of bispectral index (BIS), spectral edge frequency 95% (SEF) and median frequency (MED) in relation to a simple descriptive scale (SDS) as indicators of anaesthetic depth at different desflurane concentrations in swine. Sixteen pigs were randomly allocated to four groups. Electroencephalograms (EEG) were recorded during desflurane anaesthesia, and BIS, SEF and MED were calculated from the EEG. The agent was administered in pure oxygen at 1, 1.25, 1.5 and 1.7 MAC in randomized order. Anaesthetic depth was evaluated on a SDS. BIS decreased significantly (P<0.001) at the different anaesthetic dosages used. SEF decreased significantly (P<0.001) from basal to 1 MAC of desflurane. MED decreased significantly (P<0.001) from basal to 1 MAC and from 1 to 1.75 MAC. Good correlation was seen between SDS scores and BIS values and between SDS scores and MED values. BIS appeared to be useful to predict changes in anaesthetic depth at clinically used dosages of inhalant anaesthesia.
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Abstract
Neurophysiological techniques are widely applied to animals, both in the search as a monitor for adequacy of anaesthesia, and studies to assess the efficacy of analgesic agents. Laboratory animals have been extensively used in models to investigate pain in man. However a substantial number of studies have also used neurophysiological techniques to increase knowledge of pain in specific animal species, with the aim of improving animal welfare. This review provides an overview of neurophysiological techniques involving the brain that have been used in the assessment of pain in animals. An explanation of the methodology of EEG recording, with particular emphasis on veterinary studies, is given. Neurophysiological models developed to assess pain in different species are described, and their relevance to advancements in animal welfare or best clinical practice indicated.
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Affiliation(s)
- J C Murrell
- IVABS, College of Sciences, Massey University, Palmerston North, New Zealand.
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Haga HA, Dolvik NI. Electroencephalographic and cardiovascular variables as nociceptive indicators in isoflurane-anaesthetized horses. Vet Anaesth Analg 2005; 32:128-35. [PMID: 15877659 DOI: 10.1111/j.1467-2995.2005.00194.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
OBJECTIVE To evaluate Fourier-transformed electroencephalographic (EEG) variables, mean arterial blood pressure (MAP) and pulse rate as nociceptive indicators in isoflurane-anaesthetized horses. ANIMALS Five standardbred and three Norwegian cold-blooded trotter stallions undergoing castration, aged 2-4 years, mass 378-538 kg. MATERIALS AND METHODS All horses received intravenous (IV) detomidine (10 microg kg(-1) IV) and butorphanol (0.01 mg kg(-1) IV). Additional detomidine (4 microg kg(-1) IV) was administered in the induction area. Anaesthesia was induced with ketamine (2.5 mg kg(-1) IV) and diazepam (40 microg kg(-1) IV), and maintained for 30 minutes with isoflurane (end-tidal concentration of 1.4%) vaporized in oxygen. The electroencephalogram, MAP and pulse rate were recorded for 15 minutes, beginning 5 minutes before skin incision. Differences between the mean values of recordings taken before, and during surgery were calculated and tested for significant differences using a two-sided Student's t-test. RESULTS A significant rise in MAP and a fall in pulse rate were found. No significant change was found in any EEG variable. CONCLUSION/CLINICAL relevance Of the variables evaluated, MAP seems to be the most sensitive and reliable indicator of nociception in isoflurane-anaesthetized horses.
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Affiliation(s)
- Henning A Haga
- Department of Companion Animal Clinical Sciences, The Norwegian School of Veterinary Science, Oslo.
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Haga HA, Ranheim B. Castration of piglets: the analgesic effects of intratesticular and intrafunicular lidocaine injection. Vet Anaesth Analg 2005; 32:1-9. [PMID: 15663733 DOI: 10.1111/j.1467-2995.2004.00225.x] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
OBJECTIVE The aim of this study was to evaluate the analgesic effect of intratesticular and intrafunicular lidocaine for the surgical castration of piglets and to investigate the degree of nociception induced by lidocaine injection. STUDY DESIGN Prospective controlled experimental study. ANIMALS Forty-seven male Norwegian landrace piglets with normal testicular anatomy, aged 22 (+/-2.6 SD) days and weighing 7.4 +/- 1.4 kg. MATERIALS AND METHODS Anaesthesia was induced and maintained using halothane delivered in oxygen. End-tidal halothane was stabilized at 1.3% for 20 minutes before mean arterial blood pressure (MAP) pulse rate and electroencephalography (EEG) monitoring began. After 5 minutes of data collection, scrotal skin was desensitized with lidocaine before either an intrafunicular (IF) (n = 15) or an intratesticular (IT) (n = 16) lidocaine injection was made. Pigs in the control group (n = 16) did not receive lidocaine. Ten minutes later, a scalpel and an emasculator were used to cut the funiculus spermaticus. The MAP, pulse rate and EEG were monitored continuously for 5 minutes after castration. RESULTS During castration, MAP increased significantly, while pulse rate and EEG theta power fell significantly more in control, compared with the IT or IF groups. EEG alpha power fell more in the control group than in the IF group. No significant differences were found between the IF and IT groups. EEG, MAP and pulse rate responses to castration in the control group were significantly larger than the response to lidocaine injection. CONCLUSION/CLINICAL RELEVANCE Injecting lidocaine into the funiculus spermaticus or into the testes is effective in reducing signs of nociception caused by castration. Lidocaine injection is less noxious than castration without local anaesthetic.
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Affiliation(s)
- Henning A Haga
- Department of Companion Animal Clinical Sciences, The Norwegian School of Veterinary Science, Oslo, Norway.
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Martín-Cancho MF, Carrasco-Jiménez MS, Lima JR, Ezquerra LJ, Crisóstomo V, Usón-Gargallo J. Assessment of the relationship of bispectral index values, hemodynamic changes, and recovery times associated with sevoflurane or propofol anesthesia in pigs. Am J Vet Res 2004; 65:409-16. [PMID: 15077681 DOI: 10.2460/ajvr.2004.65.409] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
OBJECTIVE To evaluate bispectral index (BIS) values in pigs during anesthesia maintained with sevoflurane-fentanyl or propofol-fentanyl as a predictor of changes in hemodynamic parameters and duration of recovery from anesthesia. ANIMALS 12 pigs. PROCEDURE Pigs were randomly allocated to undergo 1 of 2 anesthetic regimens. Anesthesia was induced with propofol (2 mg/kg, i.v.); 6 pigs were administered sevoflurane via inhalation (1 minimum alveolar concentration [MAC] at a fresh gas flow rate of 3 L/min; group I), and 6 were administered propofol (11 mg/kg/h, i.v.; group II). All pigs received fentanyl (2.5 mg/kg, i.v., q 30 min). After abdominal surgery, pigs were allowed to recover from anesthesia. Cardiovascular variables and BIS values were recorded at intervals throughout the procedure; duration of recovery from anesthesia was noted. RESULTS No correlation was established between arterial blood pressure and BIS and between heart rate and BIS. Mean BIS at discontinuation of administration of the anesthetic agent was greater in group-II pigs (65.2 +/- 10.6 minutes) than in group-I pigs (55.8 +/- 2.9 minutes). However, recovery from anesthesia was significantly longer in group II (59.80 +/- 2.52 minutes) than in group I (9.80 +/- 2.35 minutes). CONCLUSIONS AND CLINICAL RELEVANCE In swine anesthetized with sevoflurane or propofol and undergoing abdominal surgery, the BIS value derived from an electroencephalogram at the end of anesthesia was not useful for predicting the speed of recovery from anesthesia. Moreover, BIS was not useful as a predictor of clinically important changes in arterial blood pressure and heart rate in those anesthetized pigs.
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Martín-Cancho MF, Lima JR, Luis L, Crisóstomo V, Ezquerra LJ, Carrasco MS, Usón-Gargallo J. Bispectral index, spectral edge frequency 95%, and median frequency recorded for various concentrations of isoflurane and sevoflurane in pigs. Am J Vet Res 2003; 64:866-73. [PMID: 12856771 DOI: 10.2460/ajvr.2003.64.866] [Citation(s) in RCA: 37] [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 evaluate bispectral index (BIS), spectral edge frequency 95% (SEF), and median frequency (MED) in relation to a visual analogue scale (VAS) as indicators of anesthetic depth for various concentrations of sevoflurane and isoflurane in pigs. ANIMALS 32 pigs. PROCEDURE Pigs were randomly allocated to 8 groups (4 pigs/group). An electroencephalogram (EEG) was recorded in each conscious pig. Pigs were then anesthetized by use of sevoflurane (n = 16) or isoflurane (16). Agents were administered in oxygen at minimum alveolar concentrations (MACs) of 1, 1.25, 1.5, and 1.75 MAC in a randomized order. End-tidal sevoflurane and isoflurane concentrations were maintained for 30 minutes, after which an EEG was recorded for 5 minutes; BIS, SEF, and MED were then calculated. Anesthetic depth was evaluated by use of the VAS. Cardiovascular and EEG responses to nociceptive stimuli were evaluated for each anesthetic agent. RESULTS BIS decreased significantly for the various concentrations of each anesthetic. At equivalent MACs, BIS values were significantly higher during sevoflurane-induced anesthesia than during isoflurane-induced anesthesia. Values of MED and SEF decreased significantly from basal values to 1 MAC of sevoflurane and isoflurane. For both agents, there was good correlation between VAS scores and BIS values and between VAS scores and SEF values. CONCLUSIONS AND CLINICAL RELEVANCE BIS was useful for predicting changes in anesthetic depth at clinical dosages of inhalant anesthetics. Values of BIS, SEF, and MED were significantly higher during anesthesia induced by administration of sevoflurane than during anesthesia induced by administration of isoflurance at equivalent MACs.
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