Use of Laryngeal Mask Airway and Its Removal in a Deeply Anaesthetized State Reduces Emergence Agitation after Sevoflurane Anaesthesia in Children

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1 The Journal of International Medical Research 2011; 39: Use of Laryngeal Mask Airway and Its Removal in a Deeply Anaesthetized State Reduces Emergence Agitation after Sevoflurane Anaesthesia in Children YC LEE 1,2, JM KIM 1,2, HB KO 2 AND SR LEE 1,3 1 Institute for Medical Science, Dongsan Medical Centre, Keimyung University, Daegu, Republic of Korea; 2 Department of Anaesthesiology and Pain Medicine, and 3 Department of Pharmacology, School of Medicine, Keimyung University, Daegu, Republic of Korea This study investigated the effect of laryngeal mask airway (LMA) and removal while in a deeply anaesthetized state (deep removal) compared with endotracheal tube and extubation when awake or deeply anaesthetized on the incidence of emergence agitation in children after sevoflurane anaesthesia for subumbilical surgery. Patients (2 7 years) were randomly assigned to one of three groups: ET-A group (n = 56, endotracheal tube and extubation whilst awake); ET-D group (n = 56, endotracheal tube and deep extu - bation); LMA-D group (n = 56, experienced LMA and deep removal). The incidence of postoperative emergence agitation was significantly lower in the LMA-D patients compared with patients in the ET-A group (21.4% and 41.1%, respectively). Patients in the LMA-D group required a significantly shorter stay in the postanaesthetic care unit (PACU) than ET-A patients. There were no significant differences in the incidence of postoperative emergence agitation or length of stay in the PACU between the ET- A and ET-D groups, or between the ET-D and LMA-D groups. In conclusion, using an LMA and deep removal decreased postoperative emergence agitation compared with using an endotracheal tube and awake extubation after paediatric sevoflurane anaesthesia. KEY WORDS: SEVOFLURANE; ANAESTHETICS; PAEDIATRIC ANAESTHESIA; CHILDREN; LARYNGEAL MASK AIRWAY; EMERGENCE AGITATION Introduction Emergence agitation is a well known adverse effect of sevoflurane anaesthesia. 1,2 The underlying mechanism for postoperative emergence agitation is unclear, but the potential causes include rapid emergence, intrinsic effects of sevoflurane, pain sensation, patient s age, patient s temperament, environmental stimuli and concurrently used medications. 3 5 Although various medications have been used to prevent or manage emergence agitation, 6 10 there are no definite strategies; preventing or managing emergence agitation with analgesics and sedatives can delay recovery and discharge from the postanaesthesia care unit (PACU). 11 The laryngeal mask airway (LMA) has 2385

2 proven to be an effective tool with a good safety record for airway management in paediatric patients. 12 Reports suggest that incidences of postoperative sore throat, laryngeal stimulation and anaesthetic requirement associated with use of the LMA are much less than with endotracheal tubes Extubation can safely be performed with sevoflurane anaesthesia while children are in a deeply anaesthetized state (deep extubation). 16,17 This study focused on the impact of airway management methods rather than pharmacological agents on emergence agitation. The hypothesis was tested that LMA use would decrease emergence agitation compared with use of an endotracheal tube by reducing laryngeal stimulation, throat discomfort and anaesthetic requirement. The present study also examined the hypothesis that deep extubation of the endotracheal tube or removal of the LMA (deep removal) can avoid the psychologically immature patient being frightened by awareness of intubation and inability to speak. Patients and methods STUDY POPULATION This blinded, randomized, prospective study was conducted in children aged between 2 and 7 years with American Society of Anesthesiologists (ASA) physical status I or II who were undergoing elective subumbilical surgery (inguinal herniorrhaphy, hydrocelectomy, or orchiopexy). The patients were consecutively enrolled into the study at Dongsan Medical Centre, Keimyung University, Daegu, Republic of Korea, between October 2009 and June Exclusion criteria were a known history of a neurological or psychological disorder, a history of previous anaesthesia, the presence of sleep apnoea, or patients in whom tracheal intubation or LMA insertion failed at the first attempt. The study was approved by the Institutional Review Board of Dongsan Medical Centre, Keimyung University and written informed consent was obtained from the parents of each of the children included in the study. ANAESTHESIA AND STUDY DESIGN No premedication was used before the patients were taken to the operating room. Each child was accompanied into the operating room by one parent, who was allowed to remain until the child lost consciousness. Preoperative emotional status was based on a child s behaviour during induction and was ranked on the following three-point scale by one anaesthesiologist: 1, calm, asleep, smiling, or readily accepted the mask; 2, slightly fearful or anxious; and 3, expressing fear or anxiety by verbal response, crying, or screaming. 18 Those patients with a score of 2 or 3 were considered to have a poor preoperative emotional status. Anaesthesia was induced with 8% sevoflurane in nitrous oxide/oxygen (3/1 l/min) mixture via a face mask. After adequate depth of anaesthesia was achieved, an intravenous catheter was inserted, mg/kg glycopyrrolate was given and a sodium dextrose solution (1 : 2) was infused. Electrocardiogram, heart rate, non-invasive blood pressure, body temperature, oxygen saturation, end-tidal sevoflurane and carbon dioxide concentration (Capnomac Ultima monitor; Datex-Ohmeda, Helsinki, Finland) and bispectral index (BIS; A-2000 XP monitor; Aspect Medical Systems, Natick, MA, USA) were monitored continuously. Patients were randomly assigned to one of three groups by a resident anaesthesiologist 2386

3 (H.B.K.) using a computer-generated randomization table. The ET-A group underwent tracheal intubation with an endotracheal tube (Mallinckrodt Medical, Athlone, Ireland) and extubation whilst awake. Patients in the ET-D group underwent tracheal intubation with an endotracheal tube followed by deep extubation. The LMA- D group underwent insertion of an LMA (LMA Classic ; Laryngeal Mask Company, Nicosia, Cyprus) followed by deep removal. The appropriate sizes of the endotracheal tubes and LMAs were determined according to each patient s age, following the manufacturer s guidelines. An awake state was defined as return of airway reflexes, purposeful movement and eye opening. A deeply anaesthetized state was defined as recovery of spontaneous ventilation but depressed airway reflexes and BIS < 60, with age-appropriate end-tidal sevoflurane concentration of 1.5 minimum alveolar concentration. A neuromuscular blocking agent was not administered. After anaesthesia induction, patients received 2 µg/kg fentanyl for analgesia and 0.1 mg/kg ondansetron to prevent nausea and vomiting. Anaesthesia was maintained with sevoflurane with an air/oxygen (1/1 l/min) mixture in a semiclosed circle system (Aestiva /5, GE Healthcare, New Bedford, MA, USA). The sevoflurane concentration was adjusted during surgery to maintain adequate anaesthesia, as judged by heart rate, blood pressure within 20% of preinduction values and BIS of Each type of surgery was performed by the same surgeon (i.e. one surgeon performed all inguinal herniorrhaphies, a second surgeon performed all hydrocelectomies and a third surgeon performed all orchiopexies). For patients in the ET-D and LMA-D groups, gentle oropharyngeal suction was performed after surgery, followed by deep extubation (ET-D group) or deep removal of the LMA (LMA-D group). Sevoflurane was then discontinued and oxygen was administered by a face mask. In the ET-A group, sevoflurane was discontinued and oropharyngeal suction and extubation were performed in an awake state. Tracheal intubation and extubation, and insertion and removal of the LMAs were performed by one expert anaesthesiologist who was not blinded but did not participate in any other part of the study. The duration of anaesthesia (from the beginning of induction to eye opening), duration of sevoflurane administration (from the beginning of induction to discontinuation of sevoflurane) and duration of stay in the PACU were recorded. POSTOPERATIVE ASSESSMENTS On arrival in the PACU, all children were received by one of their parents, who stayed with them until discharge. Postoperative emergence agitation was evaluated and recorded, by one anaesthesiologist (J.M.K.) who was unaware of each patient s group assignment, using the following four-point scale: 1, calm; 2, not calm but could be easily calmed; 3, not easily calmed, moderately agitated or restless; and 4, combative, excited or disoriented. 19 Postoperative emergence agitation was defined as a score of 3 or 4 and patients with these scores were treated with 1 mg/kg propofol and/or 1 µg/kg fentanyl. Patients were discharged from the PACU after haemodynamic stability, spontaneous airway maintenance, blood oxygen saturation of > 95% in room air, voluntary movement of all limbs and emotional stability were established. STATISTICAL ANALYSES The sample size required for a statistically 2387

4 significant difference in the incidence of agitation with different airway management methods was 56 patients in each group (for a level of significance of 0.05 and a power of 0.80). This estimate was based on a previous report comparing the incidence of emergence agitation after sevoflurane and propofol anaesthesia, 20 with a 25% decrease in incidence regarded as clinically significant. All statistical analyses were performed using SPSS statistical software, version 17.0 (SPSS Inc., Chicago, IL, USA) for Windows. Quantitative data were analysed by one-way analysis of variance and Tukey s multiple comparison test, and qualitative data were analysed using the χ 2 -test. A P-value of < 0.05 was considered to be statistically significant. Results The study enrolled 180 patients, 12 of whom were excluded based on the exclusion criteria. The total number of patients, therefore, included in the final analysis was 168 (n = 56 per group). There were no significant between group differences in demographic or clinical characteristics, including age, gender, weight and type of surgery (Table 1). Perioperative data are shown in Table 2. There were no significant between-group differences in the numbers of patients with a poor preoperative emotional status (score of 2 or 3 on a three-point scale), the duration of anaesthesia, or the duration of sevoflurane administration. The incidence of postoperative emergence agitation (score of 3 or 4 on a four-point scale) was significantly lower in the LMA-D group than the ET-A group (P = 0.041; Table 2). All patients with postoperative emergence agitation received treatment and, as a result, significantly fewer patients in the LMA-D group needed to receive treatment than in the ET-A group (P = 0.041). There were no significant between-group differences in the numbers of patients given each type of treatment (propofol, fentanyl or both). The duration of stay in the PACU was significantly shorter in the LMA-D group than in the ET-A group (P = 0.008). There TABLE 1: Comparison of baseline demographic and clinical characteristics between the three groups of paediatric patients in the study who underwent elective subumbilical surgery with different airway management methods ET-A ET-D LMA-D Demographic or characteristic (n = 56) (n = 56) (n = 56) Age, years a 3.3 ± ± ± 1.3 Gender, males/females b 47/9 48/8 49/7 Weight, kg a 17.5 ± ± ± 6.3 Type of surgery b Inguinal herniorrhaphy Hydrocelectomy Orchiopexy Data presented as mean ± SD or n. No statistically significant between group differences (P > 0.05); a one-way analysis of variance, Tukey s multiple comparison test; b χ 2 -test. ET-A, endotracheal extubation in an awake state; ET-D, endotracheal extubation at a deep anaesthesia level; LMA-D, laryngeal mask airway removal at a deep anaesthesia level. 2388

5 TABLE 2: Comparison of perioperative parameters for the three groups of paediatric patients in the study who underwent elective subumbilical surgery with different airway management methods ET-A ET-D LMA-D Statistical Parameter (n = 56) (n = 56) (n = 56) significance Poor preoperative emotional status b 37 (66.1) 35 (62.5) 36 (64.3) NS Duration of anaesthesia, min c 56.6 ± ± ± 10.8 NS Duration of sevoflurane administration, min d 40.9 ± ± ± 12.1 NS Postoperative emergence agitation e 23 (41.1) 19 (33.9) 12 (21.4) P = a Treatment of postoperative emergence agitation Total P = a Propofol only Fentanyl only Propofol and fentanyl Duration of PACU stay, min 32.2 ± ± ± 9.9 P = a Data presented as mean ± SD or n (%). a LMA-D group compared with ET-A group. There were no other significant between-group differences. Quantitative variables analysed by one-way analysis of variance and Tukey s multiple comparison test; qualitative variables analysed by the χ 2 -test. b Score of 2 or 3 on a three-point scale. c Duration of anaesthesia: from beginning of induction to eye opening. d Duration of sevoflurane administration: from beginning of induction to discontinuation of sevoflurane. e Score of 3 or 4 on a four-point scale. ET-A, endotracheal extubation in an awake state; ET-D, endotracheal extubation at a deep anaesthesia level; LMA-D, laryngeal mask airway removal at a deep anaesthesia level; PACU, postanaesthesia care unit; NS, not statistically significant (P > 0.05). were no statistically significant differences in the incidence of emergence agitation or in the duration of stay in the PACU between the ET-A and ET-D groups, or between the ET-D and LMA-D groups. Discussion The present study demonstrated that the use of an LMA and deep removal significantly reduced postoperative emergence agitation compared with awake extubation after use of an endotracheal tube in paediatric subumbilical surgery with sevoflurane as the anaesthetic agent. There was no difference in the incidence of postoperative emergence agitation with deep versus awake extubation or with deep extubation versus deep LMA removal. Use of a LMA has been shown to reduce emergence agitation via decreased laryngeal stimulation, decreased throat soreness, reduced need for an anaesthetic agent 12,15 and decreased sevoflurane use. Deep extubation can reduce the incidence of agitation caused by the fear of being aware of intubation, the inability to speak and with sudden exposure of a psychologically immature patient (child) to an unfamiliar environment. These factors collectively combined to reduce the incidence of postoperative emergence agitation in the LMA-D group compared with the ET-A group. Various strategies have been attempted to reduce the incidence of emergence agitation associated with sevoflurane anaesthesia in children, including the use of non-steroidal anti-inflammatory drugs, 6 benzodiazepines,

6 clonidine, 8 opioids, 9 propofol, 10 and switching inhaled anaesthetics after induction. 21 No strategy has gained widespread acceptance, and preventing or managing emergence agitation with analgesics and sedatives can delay recovery and discharge from the PACU. 11 The present study focused on comparing airway management methods rather than pharmacological agents and found that the airway management method can affect the incidence of postoperative emergence agitation. The aetiology of postoperative emergence agitation derives from multiple factors, including rapid emergence from anaesthesia, intrinsic effects of sevoflurane, duration of sevoflurane administration, pain, the patient s age, genetic predisposition, preoperative emotional status or temperament, environmental stimuli and concurrently used medications. 1,5,7,11,18,19,22 24 There is no single factor that can explain postoperative emergence agitation. The present study excluded several factors that can influence the incidence of postoperative emergence agitation. For example, there were no between-group differences regarding age, gender, or type of surgery, which can be closely related to degree of pain. The total duration of anaesthesia and duration of sevoflurane administration, as well as preoperative emotional status, were similar in all three groups. All patients were accompanied by a parent until loss of consciousness and were met by a parent in the PACU. The difference in duration of PACU stay between the ET-A and LMA-D groups is explained by the higher incidence of postoperative emergence agitation in the ET- A group. Propofol and/or fentanyl were used more frequently in the ET-A group than in the other groups, resulting in longer mean recovery times in the ET-A group. There were several limitations to the present study. The degree of postoperative pain, sore throat and throat discomfort were not evaluated, even though these can affect the incidence of agitation. 19,20 Paediatric pain is difficult to quantify and may mimic postoperative emergence agitation. 20 The age range of the patients in the present study was wide, ranging from 2 to 7 years, resulting in a large difference in the ability to express pain. It is likely that the severity of pain would not affect the incidence of agitation in this study, since all surgeries were expected to cause a similar amount of pain and there were no differences in the dose and timing of administration of analgesics. It is not possible, however, to rule out completely the effect of postoperative pain on the incidence of emergence agitation. The study did not include a group of patients with LMA and awake removal. Awake removal of LMA is not practiced routinely in the institution where the study was performed (Dongsan Medical Centre, Keimyung University), because it is known that deep removal reduces airway complications compared with awake removal, and LMA biting and clenching can occur without a bite blocker during awake removal. In conclusion, using an LMA during paediatric surgery and removing it when patients were in a deeply anaesthetized state reduced the incidence of postoperative emergence agitation compared with tracheal intubation and awake extubation after sevoflurane anaesthesia for subumbilical surgery. Acknowledgements This work was supported by a 2008 researchpromoting grant from the Institute for 2390

7 Medical Science, Dongsan Medical Centre, Keimyung University, Daegu, Republic of Korea. Conflicts of interest The authors had no conflicts of interest to declare in relation to this article. Received for publication 6 July 2011 Accepted subject to revision 12 July 2011 Revised accepted 19 November 2011 Copyright 2011 Field House Publishing LLP References 1 Lerman J, Davis PJ, Welborn LG, et al: Induction, recovery, and safety characteristics of sevoflurane in children undergoing ambulatory surgery. A comparison with halothane. Anesthesiology 1996; 84: Beskow A, Westrin P: Sevoflurane causes more postoperative agitation in children than does halothane. Acta Anaesthesiol Scand 1999; 43: Veyckemans F: Excitation and delirium during sevoflurane anesthesia in pediatric patients. Minerva Anestesiol 2002; 68: Voepel-Lewis T, Malviya S, Tait AR: A prospective cohort study of emergence agitation in the pediatric postanesthesia care unit. Anesth Analg 2003; 96: Uezono S, Goto T, Terui K, et al: Emergence agitation after sevoflurane versus propofol in pediatric patients. Anesth Analg 2000; 91: Johannesson GP, Florén M, Lindahl SG: Sevoflurane for ENT-surgery in children. A comparison with halothane. Acta Anaesthesiol Scand 1995; 39: Lapin SL, Auden SM, Goldsmith LJ, et al: Effects of sevoflurane anaesthesia on recovery in children: a comparison with halothane. Paediatr Anaesth 1999; 9: Kulka PJ, Bressem M, Tryba M: Clonidine prevents sevoflurane-induced agitation in children. Anesth Analg 2001; 93: Cohen IT, Finkel JC, Hannallah RS, et al: The effect of fentanyl on the emergence characteristics after desflurane or sevoflurane anesthesia in children. Anesth Analg 2002; 94: Aouad MT, Yazbeck-Karam VG, Nasr VG, et al: A single dose of propofol at the end of surgery for the prevention of emergence agitation in children undergoing strabismus surgery during sevoflurane anesthesia. Anesthesiology 2007; 107: Welborn LG, Hannallah RS, Norden JM, et al: Comparison of emergence and recovery characteristics of sevoflurane, desflurane, and halothane in pediatric ambulatory patients. Anesth Analg 1996; 83: Pennant JH, White PF: The laryngeal mask airway: its uses in anesthesiology. Anesthesiology 1993; 79: Yu SH, Beirne OR: Laryngeal mask airways have a lower risk of airway complications compared with endotracheal intubation: a systemic review. J Oral Maxillofac Surg 2010; 68: Joshi GP, Inagaki Y, White PF, et al: Use of the laryngeal mask airway as an alternative to the tracheal tube during ambulatory anesthesia. Anesth Analg 1997; 85: Wilkins CJ, Cramp PG, Staples J, et al: Comparison of the anesthetic requirement for tolerance of laryngeal mask airway and endotracheal tube. Anesth Analg 1992; 75: Valley RD, Freid EB, Bailey AG, et al: Tracheal extubation of deeply anesthetized pediatric patients: a comparison of desflurane and sevoflurane. Anesth Analg 2003; 96: Patel RI, Hannallah RS, Norden J, et al: Emergence airway complications in children: a comparison of tracheal extubation in awake and deeply anesthetized patients. Anesth Analg 1991; 73: Aono J, Mamiya K, Manabe M: Preoperative anxiety is associated with a high incidence of problematic behavior on emergence after halothane anesthesia in boys. Acta Anaesthesiol Scand 1999; 43: Aono J, Ueda W, Mamiya K, et al: Greater incidence of delirium during recovery from sevoflurane anesthesia in preschool boys. Anesthesiology 1997; 87: Picard V, Dumont L, Pellegrini M: Quality of recovery in children: sevoflurane versus propofol. Acta Anaesthesiol Scand 2000; 44: Bortone L, Ingelmo P, Grossi S, et al: Emergence agitation in preschool children: double-blind, randomized, controlled trial comparing sevoflurane and isoflurane anesthesia. Paediatr Anaesth 2006; 16: Wells LT, Rasch DK: Emergence delirium after sevoflurane anesthesia: a paranoid delusion? Anesth Analg 1999; 88: Eckenhoff JE, Kneale DH, Dripps RD: The incidence and etiology of postanesthetic excitement. A clinical survey. Anesthesiology 1961; 22: Kain ZN, Caldwell-Andrews AA, Maranets I, et al: Preoperative anxiety and emergence delirium and postoperative maladaptive behaviors. Anesth Analg 2004; 99: Gataure PS, Latto IP, Rust S: Complications 2391

8 associated with removal of the laryngeal mask airway: a comparison of removal in deeply anaesthetised versus awake patients. Can J Anaesth 1995; 42: Kitching AJ, Walpole AR, Blogg CE: Removal of the laryngeal mask airway in children: anaesthetized compared with awake. Br J Anaesth 1996; 76: Sinha A, Sood J: Safe removal of LMA in children at what BIS? Paediatr Anaesth 2006; 16: Author s address for correspondence Dr Yong-Cheol Lee Department of Anaesthesiology and Pain Medicine, School of Medicine, Keimyung University, 194 Dongsan-dong, Joong-gu, Daegu , Republic of Korea. yclee@dsmc.or.kr. 2392