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Red de Revistas Científicas de América Latina, el Caribe, España y Portugal Sistema de Información Científica Kadir Saritas, Zülfikar; Korkmaz, Musa; Berra Saritas, Tuba; Gul Sivaci, Remziye Comparison of the Depth of Anesthesia Produced with Dexmedetomidine-Sevofl urane or Medetomidine-Sevofl urane by Using Bispectral Index Monitoring Acta Scientiae Veterinariae, vol. 42, núm. 1, enero, 214, pp. 1-7 Universidade Federal do Rio Grande do Sul Porto Alegre, Brasil Available in: http://www.redalyc.org/articulo.oa?id=289292415 Acta Scientiae Veterinariae, ISSN (Printed Version): 1678-345 ActaSciVet@ufrgs.br Universidade Federal do Rio Grande do Sul Brasil How to cite Complete issue More information about this article Journal's homepage www.redalyc.org Non-Profit Academic Project, developed under the Open Acces Initiative

Acta Scientiae Veterinariae, 214. 42: 1199. RESEARCH ARTICLE Pub. 1199 ISSN 1679-9216 Comparison of the Depth of Anesthesia Produced with Dexmedetomidine- Sevoflurane or Medetomidine-Sevoflurane by Using Bispectral Index Monitoring Zülfikar Kadir Saritas 1, Musa Korkmaz 1, Tuba Berra Saritas 2 & Remziye Gul Sivaci 3 ABSTRACT Background: Bispectral index (BIS) monitor was developed to utilize the depth of anesthesia by estimating electroencephalogram (EEG) signals. BIS, which is the numerical value of EEG derivative, is used for evaluation of depression of central nervous system (CNS) in human medicine. The depressive effect of sedative and anaesthetic agents on CNS in human is correlated to BIS. Dexmedetomidine () is administered as continuous infusion during anesthesia and surgery in humans. is a hypnotic with high selectivity for α 2-adrenergic receptors. Materials, Methods & Results: Adult female New Zealand rabbits (mean ± SD body weight 3.8 ±.5 kg) were procured from a certified commercial source to use in medical researches. The animal number in each of the two study groups was four, for a total of eight. The rabbits were randomly divided into two equal groups (n = 4). The rabbits group were administered 2 mcg/kg of i.v. HCI for premedication. Medetomidine () group was administered 2 mcg/ kg of iv for premedication. Induction was provided by 5% of sevoflurane + 4 L/min oxygen via glove mask in the both groups. General anesthesia was maintained with 3% of sevoflurane + oxygen on spontaneous respiration for 3 min. The animals temporomandibular region was shaved; its fat was eliminated with ether before the study. Human sensors were used as BIS sensor consisted of 5 electrodes. Three were placed into frontal area as the remaining two into the preauricular area. After ensuring the connection of the sensor to the BIS monitor, BIS value was continuously followed and recorded at min (T), 1 st (T1), 5 th (T5), 7 th (T7), 9 th (T9), 15 th (T15) 2 th (T2), 25 th (T25) and at 3 th min (T3) in both groups while the rabbits were awake. At T1 measure point, and were applied; sedation was produced at T5; 5% of sevoflurane was administered through glove-mask method at T7 for induction; general anesthesia was obtained at T9 and continued during T15, T2, T25 and T3; they were awakened at the end of 3 th min. On the day preceding the study, they were sedated; their femoral arteries were localized and catheterized under local anesthesia following sedation. At T, T1, T5, T7, T9, T15, T2, T25 and T3 measure time points, the catheter-transducer connection was established for mean arterial blood pressure (MAP) measurement; for ECG monitoring, ECG electrodes were attached to all four extremities of the subjects and, ECG tracings from lead II were monitored and recorded on the multi-channel monitor. The ph was kept between 7.35-7.45, as PCO2 between 35-45 mmhg. All animals in both groups were documented during the study for Anesthesia Score (AS). MAP and BIS decline in group at the end of 1st min at statistical significance (P <.5). At the same time point, AS was recorded higher in group (P <.5). In the comparison of group with group at T5; HR, MAP and BIS markedly declined in group (P <.5); however, AS was found higher in group as being statistically significant at the same time point (P <.5). As it was at T5, Heart Rate (HR), MAP and BIS were also found statistically significantly low in group at T7 and T9; while AS was found higher as compared to group (P <.5). BIS value in group was low at a statistical significance level at T15, T2, T25 and T3 time points (P <.5). Discussion: In present study, sevoflurane administration with glove mask method provides sufficient anesthesia in the rabbits which were premedicated with and in experimental studies or surgical procedures during veterinary practice. Besides the vital parameters and AS monitoring, BIS monitoring is also an effective method in determination of the depth of anesthesia in rabbits. Keywords: bispectral index, rabbits, dexmedetomidine, medetomidine, sevoflurane, hemodynamic parameters. Received: 3 February 214 Accepted: 16 June 214 Published: 23 June 214 1 Afyon Kocatepe University, Faculty of Veterinary Medicine, Department of Surgery, Afyonkarahisar, Turkey. 2 Necmettin Erbakan University, Medical School, Department of Anesthesiology and Reanimation, Konya, Turkey. 3 Afyon Kocatepe University, Medical School, Department of Anesthesiology and Reanimation, Afyonkarahisar. CORRESPONDENCE: Z.K. SARITAS [zksaritas@hotmail.com - Fax: +9 (272) 2281349]. Faculty of Veterinary Medicine, University of Afyon Kocatepe. A.N.S Campus. TR-32 Afyonkarahisar, Turkey. 1

INTRODUCTION BIS monitor was developed to utilize the depth of anesthesia by estimating EEG signals [3,5,19,2]. BIS, which is the numerical value of EEG derivative, is used for evaluation of depression of central nervous system (CNS) in human medicine. The depressive effect of sedative and anaesthetic agents on CNS in human is correlated to BIS [15,19,2]. Inhalational anesthetics are widely used in both human and veterinary anesthetic medicine; their main advantages include being independent from hepatic or renal elimination. This reduces their biotransformation [15,19,23]. Therefore, the biotransformation of inhalational anesthetics and morbidity and mortality are very low, as compared to other anesthetics [15,2,23]. is administered as continuous infusion during anesthesia and surgery in humans. There is limited number of publication about the use of in animals. is a hypnotic with high selectivity for α 2-adrenergic receptors [18,19]. Its advantages include reduced respiratory depression, good quality of sedation, and anti-delirium, anti-agitation, anesthetic and analgesic features [19,22]. is also in reaction with α2-adrenergic receptors [1]. In this study, we aimed to determine the depth of anesthesia produced by this anesthesia protocol by using the BIS monitoring and certain vital parameters after maintaining sevoflurane anesthesia through glove mask in rabbits in which and were administered for pre-medication. MATERIALS AND METHODS Animals Adult female New Zealand rabbits (mean ± SD body weight 3.8 ±.5 kg) were procured from a certified commercial source to use in medical researches. The animal number in each of the two study groups was four, for a total of eight. Anesthesia No restriction of food or water was applied until 2 h prior to the study. The rabbits were allowed to drink water until the start of study. The rabbits were randomly divided into two equal groups (n = 4). A 22G intracath was placed into marginal auricular vein of rabbits in both groups for drug and serum administration. The rabbits in group were administered 2 2 mcg/kg of i.v. HCI 1 for premedication. group was administered 2 mcg/kg of iv 2 for premedication. Induction was provided by 5% of sevoflurane 3 + 4 L/min oxygen via glove mask in the both groups. General anesthesia was maintained with 3% of sevoflurane + oxygen on spontaneous respiration for 3 min. Bispectral index measure The animals temporomandibular region was shaved; its fat was eliminated with ether before the study. Human sensors were used as BIS sensor 4. Sensors consisted of 5 electrodes. Three were placed into frontal area as the remaining two into the preauricular area [19]. After ensuring the connection of the sensor to the BIS monitor, BIS value was continuously followed and recorded at min (T), 1 st (T1), 5 th (T5), 7 th (T7), 9 th (T9), 15 th (T15) 2 th (T2), 25 th (T25) and at 3 th min (T3) in both groups while the rabbits were awake. At T1 measure point, and were applied; sedation was produced at T5; 5% of sevoflurane was administered through glove-mask method at T7 for induction; general anesthesia was obtained at T9 and continued during T15, T2, T25 and T3; they were awakened at the end of 3 th min. Measure of Vital Parameters On the day preceding the study, they were sedated; their femoral arteries were localized and catheterized under local anesthesia following sedation. At T, T1, T5, T7, T9, T15, T2, T25 and T3 measure time points, the catheter-transducer connection was established for MAP measurement; MAP monitored on multi-channel monitor 5. For ECG monitoring, ECG electrodes were attached to all four extremities of the subjects and, ECG tracings from lead II were monitored and recorded on the multi-channel monitor. The ph 6 was kept between 7.35-7.45, as PCO 2 between 35-45 mmhg. All animals in both groups were documented during the study for AS according to the report by Saritas et al. [19], like = Awake, mobile, stops when held; 1 = Awake, mobile, stops without being held, moves in response to stimulus; 2 = Awake, stops without being held, does not move in response to stimulus; 3 = Asleep, partially responds to painful stimulus; 4 = Asleep, no response to painful stimulus; 5 = Anesthesia.

Statistical Analysis Data were analyzed with the SPSS 16. software package. A one-way ANOVA test was used to compare both groups. Test significance levels within and between the groups were checked using Duncan s test. Descriptive results are expressed as mean ± standard deviation. For all comparative tests, a value of P <.5 was considered significant. RESULTS Anesthesia induction was occurred favorable in all rabbits without excitations. The values for MAP, HR, AS and BIS at different time points are indicated in Table 1. MAP and BIS decline in group at the end of 1st min at statistical significance (P <.5) [Figures 1 & 2]. At the same time point, AS was recorded higher in group (P <.5) [Table 1]. In the comparison of group with group at T5; HR, MAP and BIS markedly declined in group (P <.5); however, AS was found higher in group as being statistically significant at the same time point (P <.5) [Table 1]. As it was at T5, HR (Figure 3), MAP and BIS were also found statistically significantly low in group at T7 and T9; while AS was found higher as compared to group (P <.5). BIS value in group was low at a statistical significance level at T15, T2, T25 and T3 time points. (P <.5) [Table 1]. Table 1. Heart rate (HR), mean arterial blood pressures (MAP), bispectral index (BIS) values and anesthesia scores (AS) in medetomidine and dexmedetomidine groups (Mean ± SD) [n = 4]. Time (min) Group HR (Pulse/min) MAP (mmhg) BIS AS 176.5 ± 13.3 92.2 ± 2.2 1 ± a 179.2 ± 1.7 93.2 ± 2.2 1 ± a 1 & 16.5 ± 6.6 173.5 ± 5.8 88.2±1.7* 89 ± 1.4 9 ± 3.7 b * 97 ±.8 a 2..5* 5 152.5 ± 5* 169.5 ± 2.8 78.1 ± 2.1* 83.2 ± 2.9 82.2 ± 5.4 c 86 ±.8 b 3.2.5* 7 149. ± 6.2* 165.1 ± 3.9 72 ± 1.8* 79.7 ± 1.5 7. ± 6.3 d * 78.2 ± 3.3 c 4.2 ±.5* 1.7 ±.5 9 145.5 ± 5* 172.1 ± 8.6 7.5 ± 1.2* 75.7 ± 2.6 52.5 ± 8.7 e * 68.2 ± 2.5 d 5. ± 4..5 15 159. ± 5.7 16.2 ± 6.3 7.5 ± 1.2 67.7 ± 1.7 61.5 ± 4.4* d 48.5 ± 2.9 e 4.7 ±.5 2 155. ± 7.3 157.7 ± 6.9 7 ± 1.4 66.7 ± 1.7 64. ± 2.8 d * 45.5 ± 1.2 ef 25 3 156.5 ± 6.6 161.1 ± 4.6 157.5 ± 5.7 16.7 ± 3.5 68 ± 1.8 66.5 ± 2.9 67.2 ± 1.9 67.2 ± 2.5 64.5 ± 6.2 d * 43.7 ± 3.5 ef 62.2 ± 5.4 d * 44 ± 3.1 ef 4.7 ±.5 *There is significant difference between groups (P <.5). The values with different letters in the same column have significant difference (P <.5). & Administration time of medetomidine ve dexmedetomidine. Administration time of sevoflurane. 3

Figure 1. BIS Values in and Group. Figure 2. Mean Arterial Pressure in and Group. Figure 3. Heart Rate (HR) in and Group. DISCUSSION The reasons for commonly the use of as a selective alfa-2 adrenergic agonist in intensive care units are sedation and causing to less respiratory depression [12,21]. Another reason of popularity of it is decreasing the opioid need in intensive care units. In their animal study, Hayashi et al. [1] reported that it eliminates the arrhythmia caused by epinephrine in dogs anesthetized with halothane. The reason of this anti-arrhythmic effect of alfa-2 adrenergic agonist is vagal activation [1,21]. is a racemic mixture of two stereoisomers, and levomedetomidine. On the other hand, it was reported that levomedetomidine has no effects over cardiovascular parameters and do not produce marked sedation and analgesia [13,24]. It is mentioned that the pharmacokinetic effects of and racemic are very similar [21]. is a potent 2-adrenoceptor agonist with sedative and analgesic features, commonly used as a pre-anesthetic agent in dogs. MAC-reducing effects of and the active racemate,, on inhaled anesthetics were reported 4 [4,8,17,24]. Thus, relatively greater CNS depression is expected at a given MAC of inhaled anaesthetic with co-administration of, compared to the same MAC of inhaled anaesthetic alone. In human anesthesiology, alpha-2 adrenergic agonists are used at low doses at a progressively increasing level to provide cardiovascular stability and tachycardia [11]. Sevoflurane is a volatile anesthetic providing rapid and smooth induction and recovery [2,7]. The effect of sevoflurane over HR is variable. It causes systemic vasodilatation and dose related declines in MAP can be seen [7,16]. Rabbits are the third most commonly used experimental animals in European countries. Rabbits carry high risk in terms of anesthesia and mortality risk is 14 times higher as compared to dogs [11]. Intubation of rabbits is difficult and they show reaction against mask induction. Rabbits are widely used in biomedical researches; major surgical procedures are performed on them. Nevertheless, it s been reported that minimum alveolar concentration (MAC) does not represent the depth of anesthesia correctly in rabbits due to the individual response to anes-

thetics. Thus, an objective and reliable system showing the depth of anesthesia is very crucial [14]. Hypotension can occur during the use of inhalational anesthetics in rabbits. This situation may be caused by the cardiovascular depressive effects of anesthetics and sedatives [9,19]. In this study, we aimed to contribute to few numbers of rabbit anesthesia studies. From this point, these rabbits were premedicated with, which is commonly used in veterinary practice recently, and, which its use has been gradually increased in intensive care units in human medicine as mentioned above; general anesthesia was produced with sevoflurane; the depth of anesthesia was determined with BIS monitoring. In this presented study, HR declined in both groups at the 1st min of pre-medication. Moreover, decline in MAP levels in group was found significant. Similarly to MAP, BIS also declined in group. In light of these data, it was understood that produces faster sedation as compared to. Additionally, the decline in HR, MAP and BIS at 5th min of premedication continued in group, it was observed that the rabbits in which was administered sedatized faster. At the time point of T7, induction was provided in all rabbits from both groups with 5% sevoflurane through glove mask method under spontaneous respiration. During the measurements at the mentioned time points, HR, MAP and BIS continued to decline in group samples. This was considered as a sign for which group became anesthetized faster and increase in AS was recorded, as parallel to BIS. The rabbits in group became anesthetized when we looked at AS. Nevertheless, BIS was recorded around 7 at the same time point. At the time point of T9, anesthesia was maintained by inhalation of 3% of sevoflurane and oxygen mixture after induction maintenance in both groups. Anesthesia produced in both group was assured with both vital parameters and BIS and AS. However, data at T15 showed the occurrence of deeper anesthesia in group. Assessment of obtained data shows that provides long term deep sedation, as it is in dogs, and deepens the sevoflurane anesthesia as compared to bolus infused. As mentioned above, sevoflurane decreases the HR and arterial blood pressure as related to the dose. According to BIS, MAP and AS, deep anesthesia occurred in group at the time of points of T15, T2, T25 and T3. BIS and MAP remained stable in group during the mentioned time points. AS showed that the rabbits in both groups were under deep anesthesia at the mentioned time points. In our previously published rabbit study [19], both group were premedicated with, induction was maintained with propofol; general anesthesia was provided with propofol infusion in one group and with isoflurane in the other. In this study, BIS was found around 6 in both propofol and isoflurane groups and deeper anesthesia was produced in propofol group. In this current study, the depth of anesthesia in the rabbits in group is consistent with the findings of previous study. CONCLUSION In conclusion, sevoflurane administration with glove mask method provides sufficient anesthesia in the rabbits which were premedicated with and in experimental studies or surgical procedures during veterinary practice. Besides the vital parameters and AS monitoring, BIS monitoring is also an effective method in determination of the depth of anesthesia in rabbits. SOURCES AND MANUFACTURERS 1 Precedex, Abbot, Istanbul, Turkey. 2 Domitor, Pfizer, Istanbul, Turkey. 3 Sevorane, Abbot, Istanbul, Turkey. 4 Covidien, Complete Monitoring System, Norwood, MA, USA 5 KMA Petas-8 Multi-Channel Monitor, Petas Ltd., Istanbul, Turkey. 6 Gastat Mini, Yokohama, Japan. Ethical approval. The study was approved by the animal local Ethics Committee (AKU, HADYEK Date: 21.11.213. Number: 294-13), Afyon Kocatepe Universty. Declaration of interest. The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper. REFERENCES 1 Baumgartner C., Bollerhey M., Ebner J., Schuster T., Henke J. & Erhardt W. 21. Effects of medetomidinemidazolam-fentanyl IV bolus injections and its reversal by spesific antagonists on cardiovascular function in rabbits. Canadian Journal of Veterinary Research. 74(4): 286-298. 5

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