For more than 20 years it has been common practice to combine

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1 PERIODICUM BIOLOGORUM UDC 57:61 VOL. 113, No 2, , 2011 CODEN PDBIAD ISSN Oiginal scientific ae/new guidelines Comaison of needed end-tidal concentation of sevofluane in childen with balanced intavenous intaoeative analgesia vesus eidual caudal intaoeative analgesia: osective andomized tial 1 MILENA KREMESEC 1 [PELA [TUPNIK 1 MENSUR SALIHOVI] 2 STELA MARI] 1 VESNA NOVAK JANKOVI^ 1 VESNA PAVER ER@EN 1 Univesity Medical Cente Ljubljana, Deatment of Anaesthesiology and Intensive Theay, Ljubljana, Slovenia 2 Univesity Hosital Cente»Seste milosdnice«clinic fo tumos, Deatment of Anaesthesiology, Zageb, Coatia Coesondence: Milena Kemesec Deatment of Anaesthesiology and Intensive Theay, Univesity Medical Cente Ljubljana, Ljubljana, Slovenia milena.kemesec@gmail.com Key wods: eidual caudal anaesthesia, sedative effects, sevofluane, alfentanil, BIS, childen Abstact Backgound and Puose: It was aleady shown that neuoaxial anaesthesia has sedative effects. The scoe of ou study was to find out whethe the combined caudal eidual block with 0.19% buivacaine deceases the sevofluane equiement because of its synegistic hynotic effect in comaison to balanced anaesthesia with intavenous alfentanil and sevofluane in childen. Mateials and Methods: Foty boys aged 1 7 yeas wee included in the study; they wee undegoing elective ochidoexy. Childen wee andomized in two gous: A (caudal block) and B (IV analgesia with oioid). Each child in gou A eceived a caudal eidual block in a dosage of 0.19% buivacaine 2.5 mg/kg. In gou B the loading dose of alfentanil was 20 mg/kg, followed by intemittent doses of mg/kg. Anaesthesia hynosis was contolled by the clinical aametes and by the Bisectal Index monito (BIS). We measued end-tidal sevofluane concentation (sevoe) at 5-minute intevals. The aim was to maintain the BIS values nea 50 though incements o decements in sevofluane concentation. Results and Conclusion: No diffeence in end-tidal sevofluane concentation (sevoe) values was obseved between the two gous. We do suose that due to the low level of caudal block we could not confim synegism between caudal eidual block with local anaesthetic and sevofluane. Received Mach 16, INTRODUCTION Fo moe than 20 yeas it has been common actice to combine eidual analgesia with geneal inhalational anaesthesia in childen, wheneve the atient s conditions and sugical ocedue as well as anaesthetist s skills ae suitable fo eidual blocks o a continuous infusion of local anaesthetic. Local anesthetics alied on neve cause a evesible but comlete block of ain tansmission, and the deaffeentation has been develoed at the neuoaxial use (1, 2). This could educe the inhalation anaesthetics equiement, needed to suess somatic movements in esonse to sugey, as well as the cadiovascula esonse to ainful sugical stimulations. Some authos demonstated that neuoaxial blocades have also diect sedative effects (2,3,4,5,6).

2 Milena Kemesec et al. Comaison of needed end-tidal concentation of sevofluane The anaesthesia hynosis has to be dee enough to event hayngeal and layngeal eflexes caused by the inseted layngeal mask (o endotacheal tube) and to event awaeness thoughout the sugical ocedue (7, 8, 9). The aim of ou study was to detemine if eidual caudal buivacaine deceases the sevofluane equiement in comaison to balanced anaesthesia using sevofluane and alfentanil. Adequate anaesthesia hynosis was measued by the BIS and by the clinical aametes. PATIENTS AND METHODS This aallel andomized study was aoved by the local ethics committee, and infomed consent in witing was obtained fom childen s aents fom 1 7 yeas of age and u to 20 kg in body weight. The childen included in the study wee ated in Ameican Society of Anaesthesiologists (ASA) hysical status I, and wee undegoing elective ochidoexy. Childen wee andomized in two gous, lanning 20 childen in each gou: A (caudal block) and B (IV analgesia with oioid). We ocessed a simle andomization with ae sheets numbeed fom 1 to 40, and ut them in a box. Patients with even numbes wee allocated into gou A, and those with odd numbes into gou B. The sheets wee ut in custody of the maton in the Pediatic Deatment and subsequently used fo the scheduled uoses. The exclusion citeia have been alied to childen with known allegies and/o local skin lesions o infection in the sacococcygeal aea. We also exlained vebally all ocedues to the aents in the esence of thei child (10, 11). Elective ochidoexy ocedues wee efomed at the Childen Sugey Deatment of the Univesity Medical Cente Ljubljana. The same team caied ou sugical oeations as well as anaesthesia. All boys wee emedicated oally with midazolam in a dosage of 0.4 mg/kg body weight. Befoe the induction of anaesthesia, ECG electodes, a cuff fo noninvasive blood essue, and a senso fo ulse oximety wee alied. Inhalation induction of anaesthesia with sevofluane via facial mask, connected to the beathing system of the»cato«esiato Daege, was efomed with sevofluane in 50% oxygen/n 2 O gas mixtues. Sevofluane was inceased gadually to 7% by using the ste by ste method. Afte loss of consciousness, IV access was obtained, the layngeal mask aiway (LMA Classic TM Layngeal Mask Comany Limited, Seychelles) was inseted and the sevofluane concentation was deceased to 4% in gou A and to 2% in gou B; afte LM insetion, fontotemoal childen s BIS Quatto electodes (Asect Medical System A-2000 TM, Newton, USA) wee alied, accoding to the witten instuctions fo the ocedue, and connected to the BIS TM monito (XP Asect Medical System, Newton, MA, USA) with integated softwae fo childen. Manual ventilation was efomed at highe concentations of sevofluane in induction, as well as afte the LMA insetion. Each child in gou A eceived on its left side osition a caudal eidual block in a dose of 2.5 mg/kg as diluted concentation of 0.19% of buivacaine; afte the blocade the sevofluane concentation was deceased to 2%. Sugical incision stated 15 minutes afte the caudal blockade, and analgesia was checked via unctue with an intademal needle at the Th 12 level. In the gou B the loading dose of alfentanil was 20 mg/kg (3 5 minutes befoe sugical skin incision) followed by intemittent doses of mg/kg, as needed, egading all clinical aametes that we measued. In both gous, anaesthesia was maintained with a mixtue of 50% oxygen/n 2 O and sevofluane. All childen eceived an infusion of 0.9% saline solution (3 ml/kg/h). The following values wee measued continuously in 5-minute intevals: heat ate, systolic-, diastolic- and mean ateial essue; ulsoxymetie (Daege oxymete), end-tidal cabondioxyde (Daege Canogah), as well as concentation of inhalation anaesthetic (Daege gas detectos) wee efomed. In 5-minute intevals we also monitoed BIS values, and fo calculation uoses of statistical values we consideed the highest and the lowest value e inteval. We tied to maintain the BIS values nea 50 though incements o decements (u and down method) in sevofluane concentation. Fo the exected effect size in sevoe q= 0.5 with 80% owe of the test and significancelevel ofa= atients e gou ae equied with the assumtion that the data will be aoximately nomally distibuted with standad deviation (SD) of s=0.5. We included 20 atients e each gou (n=20). Values ae exessed as the mean ± SD o as mediana with intequatile ange. With exloatoy data analysis we used gahical lots and Shaio-Wilk test to confim nomal distibution. Continuous vaiables wee comaed using Student t-test fo nomally distibuted vaiables and the Mann- -Withney test fo non-nomally distibuted vaiables. Ten intevals wee used to bidge the diffeences between time length fo each oeation (D i, 1.10). To detemine the effect of the sevoe on one subject and comaed to among all subjects, we used Reeated Measues Analysis of Vaiance, using the Geenhouse- -Geisse coection. Peason test was used to detemine coelation between sevoe and age and BISmax. values 0.05 wee consideed to indicate statistical significance. All analyses wee comaed using SPSS RESULTS The gous wee well balanced fo age, body weight, time of oeation ocedues (Table 1). In gou A thee wee 16 childen of 1 to 3 yeas of age, and in gou B Peiod biol, Vol 113, No 2, 2011.

3 Comaison of needed end-tidal concentation of sevofluane Milena Kemesec et al. TABLE 1 Patient chaacteistics, time of oeation, end-tidal sevofluane concentation (sevoe), heat ate (h), mean ateial essue (ma), bis min and bis max. Gou A (n=20) Gou B (n=20) P age (months) 23 (17 36) 31 (21 44) Body weight (kg) 14 ± 3 15± Time of oeation (min) 55 ± ± sevoe (% vol.) 2.2 ± ± HR (beats/min) 114 ± ± MAP (mmhg) 59 (55 64) 67 (63 71) BIS min 49 ± 5 47± BISmax 56 ± 5 54± n = numbe of atients, Values of vaiables ae shown as aveage ± SD o the median (intequatile ange), Pobability level of <0.05 was consideed as significant Mean (SD) of concentation of end-tidal sevofluane was 2.2 ± 0.5 in the caudal block gou; and 2.3 ± 0.5 in the intavenous oioid analgesia gou (=0.7). In both gous we found a statistically significant negative coelation between end-tidal sevofluane concentations and age of childen (<0.001). We found no significant coelation between end-tidal sevofluane concentation and the highest values of BIS, no with sevoe and heat ate. In gou A, contay to gou B, we found a statistically significant negative coelation between end-tidal sevofluane concentation and mean ateial blood essue (MAP) (=0.02). We found a negative coelation between BIS values and the age of the childen, statistically significant only in gou A; highe BIS values of younge childen with highe sevoe concentation. Estimated Means fo End Tidal Concentation of Sevofluane (Sevo E, vol %) time inteval 7 8 GROUP A B Figue 1. Estimated means fo End tidal concentation of sevofluane in each time inteval: gous A and B. Sevo E values wee significantly diffeent within subject duing time inteval in both gous (F(3.299, 342)=7.67, <0.001) while we did not find significant changes between subjects (F(1, 38)=0.801, =0.376) DISCUSSION In this tial we could not ove that, in the obseved time, the local anaesthetic given eidually in the caudal sace in boys that wee undegoing elective ochidoexy had anaesthesial synegistic hynotic effect. Concentations of sevofluane in combination with caudal analgesia in gou A comaed to balanced anaesthesia (sevofluane and alfentanil) in gou B, consideing the equied adequate deth of anaesthesia contolled with usual clinical signs and measued by the BIS TABLE 2 Coelation of end-tidal sevofluane concentation (sevoe) consideing age of childen, with bis max, mean ateial essue (ma) and heat ate (h) in gous a and b, and coelation of bis (minimal and maximal values) with age. sevoe/age sevoe/bismax sevoe/map sevoe/ HR age/bismin age/bismax gou A < gou B < Coelations ae exessed with Peason test (), with coesonding obability (). Peiod biol, Vol 113, No 2,

4 Milena Kemesec et al. Comaison of needed end-tidal concentation of sevofluane monito, wee not statistically significantly lowe (Table 1), desite the fact that Figue 1 shows that the mean values of the end-tidal concentation of sevofluane at each time inteval fo gous A and B wee highe in all time intevals in gou B. Based on the studies which oved a sedative effect of local anaesthetic given eidually, we howeve exected a statistically significant lowe concentation of sevofluane with the eidual caudal block (2,3,6). Local anaesthetic given eidually blocks somatic affeent imulses and should decease the neuon fiing ate in the ontine eticula system. This could lowe the level of consciousness and consequently decease the need fo geneal anaesthetics (2 4). Local anaesthetic given eidually diffuses in ceebosinal fluid (CSF), and because of its ulsation it is sead thoughout ceebosinal fluid comatments in both diections. Some authos aise the issue as to whethe subanaesthetic concentations of localanaestheticcouldinfluencethe electical activity of highe neual centes and theeby decease the measued BIS values (2). Vladic et al. studied the inulin distibution between vaious CSF comatments afte its injection into the cistena magna o lateal venticle in dogs. Afte some hous the concentation of inulin inceased in lumba subaachnoid sace (12). This study aised a question how much time local anaesthetic needs to each highe level of cental nevous system afte neuoaxial administation. In 1998 Gentili et al. oved that high sinal block had a synegistic effect on sedation highly deendent on the level of alication of local anaesthetic (5, 13). Reinoso-Babeo study which included twenty six childen fom 2 15 yeas of age found out lowe concentations of sevofluane due to a synegistic effect of the local anaesthetic given eidually in tems of anaesthetic hynosis which was also contolled by BIS (3). The use of BIS monito has been eoted to have deceased the incidence of anaesthesia awaeness. Awaeness duing anesthesia is namely a seious comlication with otential long-tem sychological consequences (8, 9). BIS monito tanslates electoencehalogahic data fom foehead electodes into a nominal scale of 0 (flat line EEG) to 100 (awake). BIS values fom 40 to 60 ae consideed being in the ange of anaesthetic hynotic state. To event wakefulness in childen, Davidson suggested that the BIS should be maintained even below 50 (14). Most authos agee that BIS monito is a useful tool in moden anaesthesiology fo maintaining anaesthesia individually, with egad to age, sex, body weight and the comlete health status of a atient, as well as the technique of anaesthesia alied (15 17). Notwithstanding the above, some authos doubt about validity of BIS measuement anaesthesia hynosis esecially not only in childen but also in adult oulation (18 23). As bain matuation and synase fomation continues afte bith u to 5 yeas of age, the validity of BIS monito in childen is theefoe questionable (18 20). Accoding to some authos, BIS monito is helful in ediatic anaesthesia (14, 18, 24) but would obably need to be adated to individual atient s age. In ou study, the coelation between the end-tidal sevofluane concentation (sevoe) and age of childen in both gous showed that this coelation is negative and statistically significant fo both gous (gou A = 0.444, <0.001; and gou B = 0.293, <0.001) as it had been exected (Table 2). Heat ate and blood essue ae two imotant clinical aametes of antinocicetion duing anaesthesia. In ou study, mean values of heat ate and blood essue wee fo all time intevals statistically lowe in the gou with the caudal block (gou A) comaed to the gou with intavenous analgesic (gou B) (=0.047; =0.003), but seven childen in gou B got atoine afte alfentanil and no child in gou A (Table 1). We found a statistically significant negative coelation between the concentation of the end-tidal sevofluane concentation (sevoe) and mean ateial blood essue in gou A (=0.022) (Table 2). Regading blood essue and heat ate and immobility of childen (movement), we could lowe the concentation of inhaled sevofluane, but the BIS values showed a tendency to go uwads, indicating a shift fom a level of anaesthesia to a level of sedation, o ossibly even a level of awaeness (14). Liteatue and clinical obsevations aleady showed that blood essue and heat ate ae not eliable aametes of the hynotic state duing anaesthesia (25). Immobility without the use of muscle elaxants duing sugey as it was the case in ou study is a useful clinical aamete of adequate deth of anaesthesia (26). Afte alying the ediatic BIS electodes and afte the blocade esectively, we deceased the sevofluane concentation with the aim of eaching BIS in the ange of 40 60, while maintaining the clinical aametes of the deth of anaesthesia. Regulation of BIS values was difficult because of thei highly volatile oscillations. Afte educing the concentation of sevofluane, BIS values in some childen stayed vey low and then suddenly elevated. The oscillation of BIS, measued at 5-minute intevals with changes obseved fom 26 60, would show that the level of anaesthesia hynosis changed instantly fom dee stage to the ue limit of anaesthetic hynosis. High oscillations also aeaed in the hase of absence of sugical intevention and with the same concentations of sevofluane (while we wee waiting fo the sugeon). The highest oscillations wee obseved in the younge childen. We also obseved aadoxical oscillations of BIS fom with vey low end-tidal concentation of sevofluane (sevoe 0, 5 0,2%) in the hase of awakening. These obsevations ae simila to the obsevations of othe investigatos whose oinion about validity of the use of BIS monito as a measuement of the level of anaesthesia hynosis in childen even u to five yeas of age is limited (18, 19, 27). As ootions of size of the heads in childen of diffeent age can be imotant, ehas thee should be moe diffeent sizes of ediatic electodes. 184 Peiod biol, Vol 113, No 2, 2011.

5 Comaison of needed end-tidal concentation of sevofluane Milena Kemesec et al. Pobably we could not confim synegism between the local anaesthetic and sevofluane because of the low level of caudal block. As oscillations of BIS values wee obseved in both gous, we believe that they ae not decisive fo the esults. REFERENCES 1. LANIER W L, IAIZZO P A, MILDE J H, SHARBROUGH F W 1994 The ceebal and systemic effects of movement in esonse to a noxious stimulus in lightly anesthetized dogs. Possible modulation of ceebal function by muscle affeents. Anesthesiology 80: HODGSON P S, LIU S S 2001 Eidual Lidocaine Deceases Sevofluane Requiement fo Adequate Deth of Anesthesia as Measued by the Bisectal Index Monito. Anesthesiology 94: REINOSO-BARBERO F, MARTINEZ-GARCIA E, HERNÁN- DES-GANCEDO MC, SIMON AM 2006 The Effect of eidual buivacaine on maintenance equiements of sevofluane evaluated by bisectal index in childen. Eu J Anaesthesiol 23: CASATI L, FERNÁNDEZ-GALINSKI S, BARRERA E, POL O, PUIG M M 2002 Isofluane equiements Duing Combined Geneal/ Eidual Anesthesia fo Majo Abdominal Sugey. Anesth Analg 94: GENTILI M, CHAU HUU P, ENEL D, BONNET H, BONNET F 1998 Sedation deends on the level of sensoy block induced by sinal anaesthesia. B J Aanaesth 1: XIAO W J, DENG X M, TANG G Z, LU M P, XU K L 2002 Caudal anesthesia educes the minimum alveola concentation of enfluane fo layngeal mask aiway emoval in boys. Can J Anesth 49: DAVIDSON A J 2007 Monitoing the anesthetic deth in childen un udate. Cu Oin Anasthesiol 20: DAUNDERER M, SCHWENDER D 2004 Unwanted wakefulness duing geneal anesthesia. Anaesthesist 53: ENGELHARDT T, MCCHEYNE A, BISSONNETTE B 2007 Awaenes duing ediatic anesthesia what is the osition of euoean ediatic anesthesiologists? Padiat Anesth 17: KRANE E J 2002 The Ethics of Regional Anesthesia in Anesthetized Childen. Tech Reg Anesth Pain Manag 6: SØREIDE E, LJUNGQVIST O 2006 Moden eoeative fasting guidelines: a summay of the esent ecommendations and emaining questions. Best Pact & Res Clin Anaesthesiol 20: VLADI] A, KLARICA M, BULAT M 2009 Dynamics of distibution of 3 H-inulin between the Ceebosinal fluid comatments. Bain Reseach 1284: YANG M K, KIM J A, AHN H J, CHOI D H 2007 Influence of the baicity of a local anaesthetic agent on sedation with oofol duing sinal anaesthesia. B J Anaesth 98: DAVIDSON A J, KWOK T 2008 Pefomance of BIS in childen using the aediatic BIS Quatto senso. Anaesth Intensive Cae 36: MORIMOTO Y, OKA S, MII M, SHINJO Y, YAMASHITA A, GOHARA T, MATSUMOTO M, SAKABE T 2002 Efficacy of bisectal index monitoing in imoving anesthetic management, economics, and use of the oeating theate. Masui 51: JOHANSEN J W, SEBEL P S 2000 Develment and clinical alication of electoencehalogahic bisectum monitoing. Anesthesiology 93: KISSIN I 2000 Deth of Anesthesia and Bisectal Index Monitoing. Anesth Analg 90: WALLENBORN J, KLUBA K, OLTHOFF D 2007 Comaative evaluation of Bisectal Index and Nacotend Index in childen below 5 yeas of age. Paediat Anaesth 17: WATCHA M F 2001 Investigations of the Bisectal Index Monito in Pediatic Anesthesia: Fist Things Fist. Anesth Analg 92: RODRIGUEZ R A, HALL L E, DUGGAN S, SPLINTER W M 2004 The bisectal index does not coelate with clinical signs of inhalational anesthesia duing sevofluane induction and aousal in childen. Can J Anesth 51: RUSSEL I F 2007 A simila BIS value does not mean a simila deth of anaesthesia. B J Anaesth 99: MANYAM S C, GUPTA D K, JOHNSON K B, WHITE J L, PACE NL, STAT M, WESTENSKOW D R, EGAN T D 2007 When Is a Bisectal Index of 60 too Low? Anesthesiology 106: LYSAKOWSKI C, DUMONT L, PELLEGRINI M, CLERGUE F, TASSONYI E 2001 Effects of fentanyl, alfentanil, emifentanil and sufentanil on loss of consciousness and Bisectal Index duing oofol induction of anesthesia. B J Anaesth 86: BANNISTER C F, BROSIUS K K, SIGL J C, MEYER B J, SEBEL P S 2001 The effect of bisectal index monitoing on anesthetic use and ecovey in childen anesthetized with sevofluane in nitous oxide. Anesth Analg 92: SICE P J A 2005 Deth of Anaesthesia. Udate in Anaesthesia (accessed Setembe 15, 2010). Available fom: htt:// wfsa/html/u19/u1910_01.htm, HAMEROFF S R 2006 The Entwined Mysteies of Anesthesia and Consciousness. Anesthesiology 10: KIM H S, OH AY, KIM C S, KIM S D, SEO K S, KIM J H 2005 Coelation of bisectal index with end-tidal sevofluane concentation and age in infants and Childen. B J Anaesth 95: Peiod biol, Vol 113, No 2,