- Email: [email protected]
Postoperative recovery following outpatient pediatric myringotomy: a comparison between sevoflurane and halothane
Original Contributions Postoperative Recovery Following Outpatient Pediatric Myringotomy: A Comparison Between Sevoflurane and Halothane Jan Halle´n, MD,* Narinder Rawal, MD, PhD,* Anil Gupta, MD, FRCA, PhD* ¨ rebro Medical Center Hospital, O ¨ rebro, Sweden Department of Anesthesiology, O
Presented in part at the Annual Meeting of the European Society of Anesthesiology (ESA), Amsterdam, 1999.
Study Objective: To assess recovery in children undergoing myringotomy and anesthetized using sevoflurane or halothane with special reference to the phenomenon of excitation reported in previous studies. Design: Prospective, randomized, single-blind study. Setting: Regional (district general) hospital. Patients: 60 healthy, physical status I children (aged 3 to 8 years) presenting for elective outpatient myringotomy. Interventions: The children were premedicated with midazolam and paracetamol and randomly allocated to one of two groups: Group H were induced with halothane (0.5% to 5%) and Group S with sevoflurane (1% to 8%). Anesthesia was maintained with oxygen (FIO2 ⫽ 0.33), nitrous oxide, and the study drug. No opioids were administered during surgery. Postoperatively, propofol was given (1 mg/kg) if the child was crying and uncontrollable on the excitation scale for ⬎5 minutes. Total analgesic consumption and side effects were recorded. Measurements and Main Results: Postoperatively, the following parameters were recorded: time to eye opening, excitation, pain, time to sit unaided, time to drink water, time to walk, and time to discharge home. No differences were found in the demographic data, duration of anesthesia and operation, time to loss of eyelash reflex, time to waking up, incidence of postoperative excitation (7% and 8% in the sevoflurane and halothane groups respectively), pain, or postoperative nausea and vomiting. The ability to sit and walk, and the time to discharge home (mean 60.4 min vs. 67.1 min, respectively) was similar between the groups. Conclusions: Although some studies have reported a high incidence of excitation following sevoflurane anaesthesia, we found no differences between halothane and sevoflurane. This finding could be due to the midazolam given as premedication as well as minimal postoperative pain in these children. © 2001 by Elsevier Science Inc.
Received for publication September 21, 2000; revised manuscript accepted for publication January 10, 2001.
Keywords: Anesthetics, inhalational: sevoflurane, halothane; excitation; postoperative recovery.
*Consultant Anaesthetist Address correspondence to Dr. Gupta at the ¨ rebro MedDepartment of Anesthesiology, O ¨ rebro, Sweden. ical Center Hospital, 701 85 O E-mail: [email protected]
Journal of Clinical Anesthesia 13:161–166, 2001 © 2001 Elsevier Science Inc. All rights reserved. 655 Avenue of the Americas, New York, NY 10010
0952-8180/01/$–see front matter PII S0952-8180(01)00236-7
Original Contributions
Introduction Sevoflurane has a low blood-gas partition coefficient, which is an advantage over halothane in that both induction and recovery have been shown to be quicker.1–3 In addition, because of its pleasant odor, sevoflurane is easy to inhale and, consequently, has become popular among pediatric anesthesiologists. Induction of anesthesia with sevoflurane has been shown to be associated with a higher incidence of excitement (35%) than with halothane (5%).4 Clinically silent but electrically generalized seizure activity has also been reported in two patients5 and seizure-like activity in another.6 Some reports have suggested that the rapid recovery following sevoflurane also results in excitation/agitation, particularly among children,1,7–9 while others attribute this to postoperative pain,2,10 thus suggesting that pain management should begin early and preferably intraoperatively. We studied a group of children undergoing day case myringotomy, which is a standardized procedure associated with minimal but constant pain. The main aim of the study was to assess induction and recovery from anesthesia, with special reference to agitation/excitation during induction and recovery in children anesthetized with either halothane or sevoflurane.
Materials and Methods ¨ rebro The protocol for the study was approved by the O County Research Ethics Committee. Verbal informed consent was taken from the parents of 60 ASA physical status I children. No child was taking any medicines regularly that might affect anesthesia or recovery. The children were in the age group 3 to 8 years, and all underwent myringotomy as a day case procedure. Midazolam was administered rectally in a dose of 0.3 mg/kg for premedication 15 to 30 minutes before induction of anesthesia in all children, which is routine in our hospital.
Anesthetic Technique The children were randomly allocated via random numbers table to one of two groups according to a singleblinded study design. The pediatric circle system was used (system F) with a fresh gas flow of 6 L/min in all cases. The increase in concentration of the gases was rapid and step-wise, starting at 0.5% for halothane and 1% for sevoflurane, increasing by 0.5% to 1% (halothane and sevoflurane, respectively) after every 3 to 4 breaths, and ending at 5% and 8%, respectively (maximum concentration). 1. Group H (Halothane): The children were induced with halothane (0.5–5%) (inspired concentration) in oxygen and nitrous oxide (FIO2, 0.33). The halothane concentration was subsequently adjusted to maintain adequate anesthesia and stable hemodynamics. 2. Group S (Sevoflurane): The children were induced with sevoflurane (1%– 8%) (inspired concentration) in oxygen and nitrous oxide (FIO2, 0.33). The sevoflurane 162
J. Clin. Anesth., vol. 13, May 2001
concentration was then adjusted to maintain adequate anesthesia and stable hemodynamics. The time to loss of eyelash reflex and centering of pupils was recorded and any episodes of hypoxia, bradycardia, arrhythmias, breath-holding, coughing, and laryngospasm during induction of anesthesia were also recorded. Monitoring included: oxygen saturation, inspired and expired concentrations of sevoflurane, halothane and nitrous oxide, heart rate, and respiratory rate (Capnomac, Datex, Helsinki, Finland) and ECG (S&W, Copenhagen, Denmark). These parameters were recorded every minute until loss of eyelash reflex, every 5 minutes during maintenance of anesthesia, and every minute after the end of anesthesia until eye opening. In all groups, paracetamol 25 mg/kg was given rectally before induction of anesthesia. No opioid analgesics were administered during the operation. At the end of the operation, the gases were turned off abruptly and 100% oxygen was delivered at 4 L/min until eye opening. Total anesthetic time was considered as the time from the start of induction (start of inhalational anesthetic) to the termination of sevoflurane or halothane administration. For the purpose of assessing recovery, the point at which the inhalational anaesthetics were turned off was considered as time zero.
Recovery from Anesthesia A. Early recovery. Early recovery was assessed by asking the children every 30 seconds to open their eyes. Once they had opened their eyes, they were transferred to the recovery ward. Oxygen saturation (SpO2) was registered in the postoperative ward until the child was fully awake. Any episodes of desaturation (SpO2 ⬍ 90%) were recorded. In the recovery ward, an experienced nurse who was blinded to the anesthetic technique recorded the events listed under Intermediate recovery (below). B. Intermediate recovery. 1. Excitation. This parameter was graded on a scale of 0 to 3, where 0 ⫽ quiet, calm child; 1 ⫽ crying but not restless; 2 ⫽ crying and restless; 3 ⫽ crying, restless, and uncontrollable. Rescue medication in the form of propofol was given in a dose of 1 mg/kg if the child was graded to be 2 or 3 on the above scale. A similar dose of propofol could be repeated once if the child remained restless after 10 minutes. The total dose of propofol given was recorded. 2. Pain. This was assessed preoperatively and every 15 minutes postoperatively for 1 hour. Assessment of pain was on a score of 1 to 4, where 1 ⫽ none, 2 ⫽ mild, 3 ⫽ moderate, 4 ⫽ severe, according to the criteria suggested by Twersky et al.11 Rescue medication in the form of fentanyl 1 g/kg was given intranasally if the intensity of pain was judged to be 3 or 4. The total analgesic consumption was recorded. 3. Time to sit unaided. This was recorded every 15 minutes by asking the child to sit unaided until he or she succeeded without distress or discomfort. 4. Time to drink water. Water was offered to the
Sevoflurane and halothane after pediatric myringotomy: Halle´n et al.
Table 1. Patient Characteristics
Table 2. Induction Time and Duration of Anesthesia/Operation
Group S (Sevoflurane) Group H (Halothane) n ⴝ 30 n ⴝ 30 Age (yrs) Weight (kg) Gender (F/M)
5.1 (2.3) 23.2 (10.1) 11/19
5.1 (2.3) 21.4 (6.6) 10/20
Note: Results are expressed as means (SD). No differences were found between the groups.
Group S Group H (Sevoflurane) (Halothane) n ⴝ 30 n ⴝ 30 Time to loss of eyelash reflex (min) Time to centring of pupils (min) Duration of operation (min) Duration of anesthesia (min)
2.3 (0.8) 5.1 (1.4) 6.8 (4.8) 17.8 (5.1)
2.6 (1.2) 5.7 (2.5) 6.4 (3.8) 17.8 (5.1)
Note: Results are expressed as means (SD). No differences were found between the groups.
children when fully awake and able to sit unaided. The time at which the child was able to drink water without vomiting was recorded. 5. Time to walk unsupported. When the children were able to sit and drink water without vomiting, they were asked to walk unaided. The time at which the child was able to walk was recorded. 6. Side effects. Any other side effects including postoperative nausea or vomiting (PONV) were recorded. When nausea was present, it was graded as mild or severe. 7. Time to discharge. An experienced recovery nurse, who was blinded to the method used, judged the duration of stay in the postoperative ward before discharge. The criteria for discharge from the postoperative ward were a fully awake child with stable hemodynamics for 30 minutes postoperatively, able to drink water and walk unaided, no nausea or vomiting and minimal pain (pain score 1 or 2), and no evidence of respiratory depression. 8. The parents were given instructions before home discharge according to the routine used in our hospital.
There were five children who were found to be agitated/ excited during recovery (scale 3– 4), this event occurred soon after awakening (5–10 min) in the sevoflurane group (3 children), but somewhat later in the halothane group (2 children) (10 –20 min) (Figures 1, 2). The incidence of nausea was somewhat higher in the halothane group (6.7%) than the sevoflurane group (3.3%), and the incidence of vomiting was higher (6.7%) for halothane than sevoflurane (0%) (p ⬎ 0.05) (Table 4).
Discussion We did not find any differences in induction, maintenance, or recovery from anesthesia between the halothane and sevoflurane groups in children undergoing myringotomy as a day case procedure. This procedure was not associated with severe postoperative pain.
Induction of Anesthesia Statistics Demographic data were analyzed using the Student’s unpaired t-test, as well as the time to drink, sit unaided, walk, and to discharge home. Incidence of excitation and PONV were analyzed using the Fisher’s exact test. p ⬍ 0.05 was considered to be statistically significant.
Results No differences were observed between the groups in age, gender, or weight of the children (Table 1). No statistically significant differences were found between the groups in relation to the time to loss of eyelash reflex and centering of pupils. The duration of anesthesia and operation were also similar between the groups (Table 2). No differences were found between the halothane and sevoflurane groups in the time to opening eyes and responding to commands. No statistically significant differences were seen between the intensity of pain and the need for supplemental analgesics, the time to sit and walk, or the time to discharge home between the groups (Table 3). No child was agitated/excited at the time of induction of anaesthesia. The incidence of excitement during recovery was low but similar between the groups (7% vs. 8%).
Time to induction was similar between the groups, which is in contrast to previous studies in which sevoflurane has been shown to result in a shorter time to loss of eyelash reflex,1–3,9 but in agreement with others.5,8,12 The similar induction times following sevoflurane could be explained partly by the fact that we used the maximum possible inspired concentrations of both sevoflurane and halothane (8% and 5%, respectively) in N2O and O2, which corresponds to approximately 4 and 5 minimum alveolar Table 3. Recovery Times
End of surgery to postoperative unit (min) Time to response to commands (min) Time to sit up (min) Time to walk (min) Duration of postoperative stay (min)
Group S (Sevoflurane) n ⴝ 30
Group H (Halothane) n ⴝ 30
5.8 (1.6)
6.3 (3.1)
32.0 (16.6)
38.3 (16.4)
43.0 (16.4) 54.1 (7.8) 60.4 (9.9)
42.0 (14.2) 62.2 (26.3) 67.1 (28.3)
Note: Results are expressed as means (SD). No differences were found between the groups. J. Clin. Anesth., vol. 13, May 2001
163
Original Contributions
Figure 1. Postoperative excitation in the halothane group. The total number of patients decreases with time as they are successively discharged from the ambulatory stay unit. No differences were seen between the groups at any of the time periods.
concentration (MAC), respectively, in children in the age group 3 to 10 years. The higher (relative) MAC value in the halothane group could explain the rapidity of induction in this group. It is possible that equipotent concentrations of these anesthetics at induction could have resulted in shorter induction times in the sevoflurane group. We did not find any significant complications during induction in either group, suggesting that both sevoflurane and halothane are probably equally good for induction of anesthesia in children.
Recovery from Anesthesia Early recovery (time to eye opening and obeying commands) was similar in both groups. This finding was in contrast to previous studies where early recovery has been shown to be more rapid following sevoflurane than halothane.1,8 In our study, the operation and anesthetic times were ⬍15 minutes in both groups and, consequently, it is likely that pharmacokinetic stability had not been achieved and the tissues remained unsaturated with the
Figure 2. Postoperative excitation in the sevoflurane group. The total number of patients decreases with time as they are successively discharged from the ambulatory stay unit. No differences were seen between the groups at any of the time periods. 164
J. Clin. Anesth., vol. 13, May 2001
Sevoflurane and halothane after pediatric myringotomy: Halle´n et al.
Table 4. Side Effects/Complications
Moderate-severe pain (%) Nausea (%) Vomiting (%) Vomiting after drinking (%)
Group S (Sevoflurane) n ⴝ 30
Group H (Halothane) n ⴝ 30
1 (3.3%) 1 (3.3%) 0 (0%) 0 (0%)
2 (6.7%) 1 (6.7%) 2 (6.7%) 1 (3.3%)
Note: Results are expressed as numbers (%) of children experiencing side effects.
gases during this short anesthetic. As halothane has a higher oil:gas partition coefficient, it binds to fatty tissues, which can result in prolonged recovery. However, this usually occurs during longer operative procedures but for short procedures, such as myringotomies, minimal amounts of halothane are likely to have reached fatty tissues and, hence, the rapid early recovery. Early recovery was found to be longer after sevoflurane compared to halothane by Ariffin et al.13 in children undergoing tooth extraction, and similar between sevoflurane and halothane by Johanesson et al.2 following ENT surgery and Welborn et al.14 following adenoidectomy and grommet insertion. Some of the earlier studies have had a mixed population of children undergoing different operative procedures with varying anesthetic duration,1,15 and hence it can sometimes be difficult to interpret the results in a more homogeneous population undergoing a standardized procedure. The time to home discharge was also similar between the groups in our study, a finding that is consistent with many previous studies.1,13–15 Because criteria for home discharge, particularly in children, are insensitive and often not objective, it is usually difficult to show differences in discharge times, and comparisons between different anesthetics have seldom shown clear benefit in favor of the modern inhalation anesthetics.14
Postoperative Complications Some studies have suggested that early recovery from sevoflurane anesthesia in children may be associated with agitation/excitement.1,2,8 Although the cause for agitation remains uncertain, three factors have been described as being contributory: 1) rapid recovery following anesthesia, 2) preschool boys,7 and 3) postoperative pain.1,2,10 Because recovery following desflurane is also rapid, and desflurane anesthesia has also been reported to cause agitation in children,14,16 it could be argued that rapid recovery is the more likely mechanism. Some case studies have also suggested that sevoflurane may cause epileptogenic activity, which has been confirmed in animal studies,17,18 and, recently, even in humans.19,20 In the present study, we found that the incidence of excitation was low and similar in both the sevoflurane and halothane groups. However, the children underwent myringotomy and grommet insertion, which is not usually associated with
severe pain postoperatively. Also, all the children were given midazolam as premedication as well as paracetamol for postoperative pain. Consequently, the overall incidence of agitation was low (7– 8%), and we were unable to detect any significant differences between the groups. The effect of paracetamol in reducing excitation has been shown by Johanesson et al.,2 and we believe that the inclusion of midazolam as premedication further reduced this problem to very low levels. Neither Welborn et al.14 nor Calderon et al.21 found any difference in the incidence of excitation between halothane and sevoflurane, but their pediatric patients were also premedicated with midazolam po or intranasally, respectively. In conclusion, we found no differences between halothane and sevoflurane for the induction and maintenance of anesthesia in children undergoing myringotomy as an outpatient procedure. The incidence of postoperative excitation with sevoflurane was similar to that after halothane in premedicated children with minimal postoperative pain.
Acknowledgments We wish to thank the nurses in the Anaesthesia and ENT Surgery department for their cooperation and support during the various stages of this study.
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;84:1332– 40. 2. Johannesson GP, Flore´n M, Lindahl SG: Sevoflurane for ENTsurgery in children. A comparison with halothane. Acta Anaesthesiol Scand 1995;39:546 –50. 3. Meretoja OA, Taivainen T, Raiha L, et al.: Sevoflurane-nitrous oxide for paediatric bronchoscopy and gastroscopy. Br J Anaesth 1997;79:143– 4. 4. Sarner JB, Levine M, Davis PJ, Lerman J, Cook DR, Motoyama EK: Clinical characteristics of sevoflurane in children. A comparison with halothane. Anesthesiology 1995;82:38 – 46. 5. Komatsu H, Taie S, Endo S, et al: Electrical seizures during sevoflurane anesthesia in two pediatric patients with epilepsy. Anesthesiology 1994;81:1535–7. 6. Adachi M, Ikemoto Y, Kubo K, Takuma C: Seizure-like movements during induction of anaesthesia with sevoflurane. Br J Anaesth 1992;68:214 –5. 7. Aono J, Ueda W, Mamiya K, Takimoto E, Manabe M: Greater incidence of delirium during recovery from sevoflurane anaesthesia in preschool boys. Anesthesiology 1997;87:1298 –300. 8. Naito Y, Tamai S, Shingu K, Fujimori R, Mori K: Comparison between sevoflurane and halothane for paediatric ambulatory anaesthesia. Br J Anaesth 1991;67:387–9. 9. Taivainen T, Tiainen P, Meretoja OA, Raiha L, Rosenberg PH: Comparison of the effects of sevoflurane and halothane on the quality of anaesthesia and serum glutathione transferase alpha and fluoride in paediatric patients. Br J Anaesth 1994;73:590 –5. 10. Davis PJ, Greenberg JA, Gendelman M, et al: Does sevoflurane really cause postoperative agitation? Anesthesiology 1998;89:1317. 11. Twersky RS: New modalities in outpatient postoperative pain management. J Clin Anesth 1993;5(6 Suppl 1):57S– 63S. 12. Piat V, Dubois MC, Johanet S, Murat I: Induction and recovery J. Clin. Anesth., vol. 13, May 2001
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characteristics and hemodynamic responses to sevoflurane and halothane in children. Anesth Analg 1994;79:840 – 4. Ariffin SA, Whyte JA, Malins AF, Cooper GM: Comparison of induction and recovery between sevoflurane and halothane supplementation of anaesthesia in children undergoing outpatient dental extractions. Br J Anaesth 1997;78:157–9. 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;83:917–20. Sury MRJ, Black A, Hemington L, et al: A comparison of recovery characteristics of sevoflurane and halothane in children. Anaesthesia 1996;51:543– 6. Grundmann U, Uth M, Eichner A, Wilhelm W, Larsen R: Total intravenous anaesthesia with propofol and remifentanil in paediatric patients: a comparison with a desflurane-nitrous oxide inhalation anaesthesia. Acta Anaesthesiol Scand 1998;42:845–50.
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17. Schultz B, Schultz A: Epileptiform EEG potentials with sevoflurane [Letter]. Anaesth Intensive Care 1998;26:329. 18. Komatsu H, Nogaya J, Ogli K: Volatile anaesthetics as central nervous system excitants. Ann Acad Med Singapore 1994;23(6 Suppl):130 – 8. 19. Vakkuri A, Jantti M, Mennander S, et al: Sevoflurane inhalation induction: epileptiform EEG in children. Eur J Anesthesiology 2000;17:137. 20. Constant I, Dubois M-C, Piat V, Moutard ML, McCue M, Murat I: Changes in electroencephalogram and autonomic cardiovascular activity during induction of anesthesia with sevoflurane compared with halothane in children. Anesthesiology 1999;91:1604 –15. 21. Calderon E, Torres LM, Aguado JA, de Antonio P, Mora R, Almarcha JM: Comparative study of sevoflurane and nitrous oxide in paediatric anaesthesia: efficacy and hemodynamic characteristics during induction. Rev Esp Anestesiol Reanim 1998;45: 126 –9.
Presented in part at the Annual Meeting of the European Society of Anesthesiology (ESA), Amsterdam, 1999.
Study Objective: To assess recovery in children undergoing myringotomy and anesthetized using sevoflurane or halothane with special reference to the phenomenon of excitation reported in previous studies. Design: Prospective, randomized, single-blind study. Setting: Regional (district general) hospital. Patients: 60 healthy, physical status I children (aged 3 to 8 years) presenting for elective outpatient myringotomy. Interventions: The children were premedicated with midazolam and paracetamol and randomly allocated to one of two groups: Group H were induced with halothane (0.5% to 5%) and Group S with sevoflurane (1% to 8%). Anesthesia was maintained with oxygen (FIO2 ⫽ 0.33), nitrous oxide, and the study drug. No opioids were administered during surgery. Postoperatively, propofol was given (1 mg/kg) if the child was crying and uncontrollable on the excitation scale for ⬎5 minutes. Total analgesic consumption and side effects were recorded. Measurements and Main Results: Postoperatively, the following parameters were recorded: time to eye opening, excitation, pain, time to sit unaided, time to drink water, time to walk, and time to discharge home. No differences were found in the demographic data, duration of anesthesia and operation, time to loss of eyelash reflex, time to waking up, incidence of postoperative excitation (7% and 8% in the sevoflurane and halothane groups respectively), pain, or postoperative nausea and vomiting. The ability to sit and walk, and the time to discharge home (mean 60.4 min vs. 67.1 min, respectively) was similar between the groups. Conclusions: Although some studies have reported a high incidence of excitation following sevoflurane anaesthesia, we found no differences between halothane and sevoflurane. This finding could be due to the midazolam given as premedication as well as minimal postoperative pain in these children. © 2001 by Elsevier Science Inc.
Received for publication September 21, 2000; revised manuscript accepted for publication January 10, 2001.
Keywords: Anesthetics, inhalational: sevoflurane, halothane; excitation; postoperative recovery.
*Consultant Anaesthetist Address correspondence to Dr. Gupta at the ¨ rebro MedDepartment of Anesthesiology, O ¨ rebro, Sweden. ical Center Hospital, 701 85 O E-mail: [email protected]
Journal of Clinical Anesthesia 13:161–166, 2001 © 2001 Elsevier Science Inc. All rights reserved. 655 Avenue of the Americas, New York, NY 10010
0952-8180/01/$–see front matter PII S0952-8180(01)00236-7
Original Contributions
Introduction Sevoflurane has a low blood-gas partition coefficient, which is an advantage over halothane in that both induction and recovery have been shown to be quicker.1–3 In addition, because of its pleasant odor, sevoflurane is easy to inhale and, consequently, has become popular among pediatric anesthesiologists. Induction of anesthesia with sevoflurane has been shown to be associated with a higher incidence of excitement (35%) than with halothane (5%).4 Clinically silent but electrically generalized seizure activity has also been reported in two patients5 and seizure-like activity in another.6 Some reports have suggested that the rapid recovery following sevoflurane also results in excitation/agitation, particularly among children,1,7–9 while others attribute this to postoperative pain,2,10 thus suggesting that pain management should begin early and preferably intraoperatively. We studied a group of children undergoing day case myringotomy, which is a standardized procedure associated with minimal but constant pain. The main aim of the study was to assess induction and recovery from anesthesia, with special reference to agitation/excitation during induction and recovery in children anesthetized with either halothane or sevoflurane.
Materials and Methods ¨ rebro The protocol for the study was approved by the O County Research Ethics Committee. Verbal informed consent was taken from the parents of 60 ASA physical status I children. No child was taking any medicines regularly that might affect anesthesia or recovery. The children were in the age group 3 to 8 years, and all underwent myringotomy as a day case procedure. Midazolam was administered rectally in a dose of 0.3 mg/kg for premedication 15 to 30 minutes before induction of anesthesia in all children, which is routine in our hospital.
Anesthetic Technique The children were randomly allocated via random numbers table to one of two groups according to a singleblinded study design. The pediatric circle system was used (system F) with a fresh gas flow of 6 L/min in all cases. The increase in concentration of the gases was rapid and step-wise, starting at 0.5% for halothane and 1% for sevoflurane, increasing by 0.5% to 1% (halothane and sevoflurane, respectively) after every 3 to 4 breaths, and ending at 5% and 8%, respectively (maximum concentration). 1. Group H (Halothane): The children were induced with halothane (0.5–5%) (inspired concentration) in oxygen and nitrous oxide (FIO2, 0.33). The halothane concentration was subsequently adjusted to maintain adequate anesthesia and stable hemodynamics. 2. Group S (Sevoflurane): The children were induced with sevoflurane (1%– 8%) (inspired concentration) in oxygen and nitrous oxide (FIO2, 0.33). The sevoflurane 162
J. Clin. Anesth., vol. 13, May 2001
concentration was then adjusted to maintain adequate anesthesia and stable hemodynamics. The time to loss of eyelash reflex and centering of pupils was recorded and any episodes of hypoxia, bradycardia, arrhythmias, breath-holding, coughing, and laryngospasm during induction of anesthesia were also recorded. Monitoring included: oxygen saturation, inspired and expired concentrations of sevoflurane, halothane and nitrous oxide, heart rate, and respiratory rate (Capnomac, Datex, Helsinki, Finland) and ECG (S&W, Copenhagen, Denmark). These parameters were recorded every minute until loss of eyelash reflex, every 5 minutes during maintenance of anesthesia, and every minute after the end of anesthesia until eye opening. In all groups, paracetamol 25 mg/kg was given rectally before induction of anesthesia. No opioid analgesics were administered during the operation. At the end of the operation, the gases were turned off abruptly and 100% oxygen was delivered at 4 L/min until eye opening. Total anesthetic time was considered as the time from the start of induction (start of inhalational anesthetic) to the termination of sevoflurane or halothane administration. For the purpose of assessing recovery, the point at which the inhalational anaesthetics were turned off was considered as time zero.
Recovery from Anesthesia A. Early recovery. Early recovery was assessed by asking the children every 30 seconds to open their eyes. Once they had opened their eyes, they were transferred to the recovery ward. Oxygen saturation (SpO2) was registered in the postoperative ward until the child was fully awake. Any episodes of desaturation (SpO2 ⬍ 90%) were recorded. In the recovery ward, an experienced nurse who was blinded to the anesthetic technique recorded the events listed under Intermediate recovery (below). B. Intermediate recovery. 1. Excitation. This parameter was graded on a scale of 0 to 3, where 0 ⫽ quiet, calm child; 1 ⫽ crying but not restless; 2 ⫽ crying and restless; 3 ⫽ crying, restless, and uncontrollable. Rescue medication in the form of propofol was given in a dose of 1 mg/kg if the child was graded to be 2 or 3 on the above scale. A similar dose of propofol could be repeated once if the child remained restless after 10 minutes. The total dose of propofol given was recorded. 2. Pain. This was assessed preoperatively and every 15 minutes postoperatively for 1 hour. Assessment of pain was on a score of 1 to 4, where 1 ⫽ none, 2 ⫽ mild, 3 ⫽ moderate, 4 ⫽ severe, according to the criteria suggested by Twersky et al.11 Rescue medication in the form of fentanyl 1 g/kg was given intranasally if the intensity of pain was judged to be 3 or 4. The total analgesic consumption was recorded. 3. Time to sit unaided. This was recorded every 15 minutes by asking the child to sit unaided until he or she succeeded without distress or discomfort. 4. Time to drink water. Water was offered to the
Sevoflurane and halothane after pediatric myringotomy: Halle´n et al.
Table 1. Patient Characteristics
Table 2. Induction Time and Duration of Anesthesia/Operation
Group S (Sevoflurane) Group H (Halothane) n ⴝ 30 n ⴝ 30 Age (yrs) Weight (kg) Gender (F/M)
5.1 (2.3) 23.2 (10.1) 11/19
5.1 (2.3) 21.4 (6.6) 10/20
Note: Results are expressed as means (SD). No differences were found between the groups.
Group S Group H (Sevoflurane) (Halothane) n ⴝ 30 n ⴝ 30 Time to loss of eyelash reflex (min) Time to centring of pupils (min) Duration of operation (min) Duration of anesthesia (min)
2.3 (0.8) 5.1 (1.4) 6.8 (4.8) 17.8 (5.1)
2.6 (1.2) 5.7 (2.5) 6.4 (3.8) 17.8 (5.1)
Note: Results are expressed as means (SD). No differences were found between the groups.
children when fully awake and able to sit unaided. The time at which the child was able to drink water without vomiting was recorded. 5. Time to walk unsupported. When the children were able to sit and drink water without vomiting, they were asked to walk unaided. The time at which the child was able to walk was recorded. 6. Side effects. Any other side effects including postoperative nausea or vomiting (PONV) were recorded. When nausea was present, it was graded as mild or severe. 7. Time to discharge. An experienced recovery nurse, who was blinded to the method used, judged the duration of stay in the postoperative ward before discharge. The criteria for discharge from the postoperative ward were a fully awake child with stable hemodynamics for 30 minutes postoperatively, able to drink water and walk unaided, no nausea or vomiting and minimal pain (pain score 1 or 2), and no evidence of respiratory depression. 8. The parents were given instructions before home discharge according to the routine used in our hospital.
There were five children who were found to be agitated/ excited during recovery (scale 3– 4), this event occurred soon after awakening (5–10 min) in the sevoflurane group (3 children), but somewhat later in the halothane group (2 children) (10 –20 min) (Figures 1, 2). The incidence of nausea was somewhat higher in the halothane group (6.7%) than the sevoflurane group (3.3%), and the incidence of vomiting was higher (6.7%) for halothane than sevoflurane (0%) (p ⬎ 0.05) (Table 4).
Discussion We did not find any differences in induction, maintenance, or recovery from anesthesia between the halothane and sevoflurane groups in children undergoing myringotomy as a day case procedure. This procedure was not associated with severe postoperative pain.
Induction of Anesthesia Statistics Demographic data were analyzed using the Student’s unpaired t-test, as well as the time to drink, sit unaided, walk, and to discharge home. Incidence of excitation and PONV were analyzed using the Fisher’s exact test. p ⬍ 0.05 was considered to be statistically significant.
Results No differences were observed between the groups in age, gender, or weight of the children (Table 1). No statistically significant differences were found between the groups in relation to the time to loss of eyelash reflex and centering of pupils. The duration of anesthesia and operation were also similar between the groups (Table 2). No differences were found between the halothane and sevoflurane groups in the time to opening eyes and responding to commands. No statistically significant differences were seen between the intensity of pain and the need for supplemental analgesics, the time to sit and walk, or the time to discharge home between the groups (Table 3). No child was agitated/excited at the time of induction of anaesthesia. The incidence of excitement during recovery was low but similar between the groups (7% vs. 8%).
Time to induction was similar between the groups, which is in contrast to previous studies in which sevoflurane has been shown to result in a shorter time to loss of eyelash reflex,1–3,9 but in agreement with others.5,8,12 The similar induction times following sevoflurane could be explained partly by the fact that we used the maximum possible inspired concentrations of both sevoflurane and halothane (8% and 5%, respectively) in N2O and O2, which corresponds to approximately 4 and 5 minimum alveolar Table 3. Recovery Times
End of surgery to postoperative unit (min) Time to response to commands (min) Time to sit up (min) Time to walk (min) Duration of postoperative stay (min)
Group S (Sevoflurane) n ⴝ 30
Group H (Halothane) n ⴝ 30
5.8 (1.6)
6.3 (3.1)
32.0 (16.6)
38.3 (16.4)
43.0 (16.4) 54.1 (7.8) 60.4 (9.9)
42.0 (14.2) 62.2 (26.3) 67.1 (28.3)
Note: Results are expressed as means (SD). No differences were found between the groups. J. Clin. Anesth., vol. 13, May 2001
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Figure 1. Postoperative excitation in the halothane group. The total number of patients decreases with time as they are successively discharged from the ambulatory stay unit. No differences were seen between the groups at any of the time periods.
concentration (MAC), respectively, in children in the age group 3 to 10 years. The higher (relative) MAC value in the halothane group could explain the rapidity of induction in this group. It is possible that equipotent concentrations of these anesthetics at induction could have resulted in shorter induction times in the sevoflurane group. We did not find any significant complications during induction in either group, suggesting that both sevoflurane and halothane are probably equally good for induction of anesthesia in children.
Recovery from Anesthesia Early recovery (time to eye opening and obeying commands) was similar in both groups. This finding was in contrast to previous studies where early recovery has been shown to be more rapid following sevoflurane than halothane.1,8 In our study, the operation and anesthetic times were ⬍15 minutes in both groups and, consequently, it is likely that pharmacokinetic stability had not been achieved and the tissues remained unsaturated with the
Figure 2. Postoperative excitation in the sevoflurane group. The total number of patients decreases with time as they are successively discharged from the ambulatory stay unit. No differences were seen between the groups at any of the time periods. 164
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Sevoflurane and halothane after pediatric myringotomy: Halle´n et al.
Table 4. Side Effects/Complications
Moderate-severe pain (%) Nausea (%) Vomiting (%) Vomiting after drinking (%)
Group S (Sevoflurane) n ⴝ 30
Group H (Halothane) n ⴝ 30
1 (3.3%) 1 (3.3%) 0 (0%) 0 (0%)
2 (6.7%) 1 (6.7%) 2 (6.7%) 1 (3.3%)
Note: Results are expressed as numbers (%) of children experiencing side effects.
gases during this short anesthetic. As halothane has a higher oil:gas partition coefficient, it binds to fatty tissues, which can result in prolonged recovery. However, this usually occurs during longer operative procedures but for short procedures, such as myringotomies, minimal amounts of halothane are likely to have reached fatty tissues and, hence, the rapid early recovery. Early recovery was found to be longer after sevoflurane compared to halothane by Ariffin et al.13 in children undergoing tooth extraction, and similar between sevoflurane and halothane by Johanesson et al.2 following ENT surgery and Welborn et al.14 following adenoidectomy and grommet insertion. Some of the earlier studies have had a mixed population of children undergoing different operative procedures with varying anesthetic duration,1,15 and hence it can sometimes be difficult to interpret the results in a more homogeneous population undergoing a standardized procedure. The time to home discharge was also similar between the groups in our study, a finding that is consistent with many previous studies.1,13–15 Because criteria for home discharge, particularly in children, are insensitive and often not objective, it is usually difficult to show differences in discharge times, and comparisons between different anesthetics have seldom shown clear benefit in favor of the modern inhalation anesthetics.14
Postoperative Complications Some studies have suggested that early recovery from sevoflurane anesthesia in children may be associated with agitation/excitement.1,2,8 Although the cause for agitation remains uncertain, three factors have been described as being contributory: 1) rapid recovery following anesthesia, 2) preschool boys,7 and 3) postoperative pain.1,2,10 Because recovery following desflurane is also rapid, and desflurane anesthesia has also been reported to cause agitation in children,14,16 it could be argued that rapid recovery is the more likely mechanism. Some case studies have also suggested that sevoflurane may cause epileptogenic activity, which has been confirmed in animal studies,17,18 and, recently, even in humans.19,20 In the present study, we found that the incidence of excitation was low and similar in both the sevoflurane and halothane groups. However, the children underwent myringotomy and grommet insertion, which is not usually associated with
severe pain postoperatively. Also, all the children were given midazolam as premedication as well as paracetamol for postoperative pain. Consequently, the overall incidence of agitation was low (7– 8%), and we were unable to detect any significant differences between the groups. The effect of paracetamol in reducing excitation has been shown by Johanesson et al.,2 and we believe that the inclusion of midazolam as premedication further reduced this problem to very low levels. Neither Welborn et al.14 nor Calderon et al.21 found any difference in the incidence of excitation between halothane and sevoflurane, but their pediatric patients were also premedicated with midazolam po or intranasally, respectively. In conclusion, we found no differences between halothane and sevoflurane for the induction and maintenance of anesthesia in children undergoing myringotomy as an outpatient procedure. The incidence of postoperative excitation with sevoflurane was similar to that after halothane in premedicated children with minimal postoperative pain.
Acknowledgments We wish to thank the nurses in the Anaesthesia and ENT Surgery department for their cooperation and support during the various stages of this study.
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