- Email: [email protected]
Comparison of sevoflurane and halothane for outpatient dental anaesthesia in children
British Journal of Anaesthesia 1997; 79: 280–284
Comparison of sevoflurane and halothane for outpatient dental anaesthesia in children
S. T. PARIS, M. CAFFERKEY, M. TARLING, P. HANCOCK, P. M. YATE AND P. J. FLYNN
Summary In a prospective, randomized, double-blind clinical study, we have studied 100 children, aged 2–12 yr, to compare halothane and sevoflurane in outpatient dental anaesthesia. All patients were unpremedicated and received inhalation induction using nitrous oxide in oxygen supplemented with either halothane (maximum inspired concentration 5%) or sevoflurane (maximum inspired concentration 8%). Time to loss of the eyelash reflex was more rapid using sevoflurane although time to adequate anaesthesia (to allow insertion of a mouth prop) was slower in the sevoflurane group. The incidence of cardiac arrhythmia was higher during halothane (62%) than during sevoflurane anaesthesia (28%) (P:0.005) and the arrhythmias were more often ventricular in origin. The two agents were comparable in terms of ease of use and quality of anaesthesia, and times to eye opening and satisfying discharge criteria were similar. We conclude that sevoflurane has qualities that have made halothane the most used inhalation agent for children, and that it is superior to halothane in dental outpatients where cardiac arrhythmias are a particular problem. (Br. J. Anaesth. 1997; 79: 280–284). Key words Anaesthetics volatile, halothane. sevoflurane. Surgery, dental. Children.
Anaesthetics
volatile,
It is becoming increasingly apparent that sevoflurane has the potential to be the inhalation induction agent of choice in children.1–4 It is relatively pleasant smelling, non-irritant and has a rapid onset and offset of action by virtue of its low blood-gas solubility. Halothane is still used widely in paediatric dental outpatient anaesthesia as it is relatively non-pungent and provides smooth induction and recovery. Its main disadvantages are a strong odour, cardiovascular depression, a propensity to cause arrhythmias and rarely hepatic necrosis, especially after repeated exposures. During dental surgery, the incidence of arrhythmia during halothane anaesthesia has been reported to be as high as 75%.5 The use of enflurane or isoflurane reduces the incidence of arrhythmias during oral surgery but both are inferior to halothane in terms of ease of induction
and quality of anaesthesia.5–7 This study was designed to compare the incidence and type of arrhythmia, and quality of anaesthesia and recovery during sevoflurane and halothane anaesthesia in children undergoing outpatient dental extraction.
Patients and methods After obtaining Ethics Committee approval and written parental consent, we studied 100 unpremedicated children, ASA I–II, aged 2–12 yr, undergoing outpatient dental extractions under general anaesthesia; patients were allocated randomly to one of two groups to receive either sevoflurane or halothane. Electrocardiographic limb leads were attached to the patient before induction of anaesthesia and a continuous record of lead II was obtained together with a visual oscilloscope display. A paediatric pulse oximetry probe was applied before induction of anaesthesia and oxygen saturation (SpO2 ) was monitored continuously throughout surgery and during recovery from anaesthesia. Arterial pressure readings before and after induction were obtained whenever possible and recorded. The time of induction, placement of the mouth prop, dental extractions and discontinuation of anaesthetic were recorded by a blinded observer who also assessed the incidence of complications during anaesthesia and recovery. Complications were graded on a scale from 0 to 3: 0:not present; 1:present but not troublesome; 2:causing interference with technique or requiring treatment; 3:so troublesome that technique had to be abandoned or patient needed admission to hospital. Complications assessed were intolerance to the vapour, breath-holding, coughing, salivation, laryngospasm, vomiting, SpO2 :90%, rigidity, excitatory movements and shivering. In the recovery area, times to eye opening to command and to “street fitness” (able to drink and walk around the recovery area unaided) were also recorded. Dental extractions were carried out in the supine position and anaesthesia was administered by one
S. T. PARIS, BSC, MB, BS, FRCA, M. TARLING, SRN, BSC, MSC, P. HANCOCK, BSC, P. J. FLYNN, MB, BCH, FFARCSI, FRCA (Anaesthetics Unit); M. CAFFERKEY, MB, CHB, MRCP (Department of Medicine); P. M. YATE, MB, FRCA (Anaesthetics Department); Royal Hospitals NHS Trust, Whitechapel, London E1 1BB. Accepted for publication: April 3, 1997.
Sevoflurane and halothane for dental anaesthesia in children Table 1
281
Patient characteristics and clinical data (median (95% central range) or number of patients)
Age (yr) Weight (kg) Sex (M/F) Race (Asian /Caucasian /Negroid) Cooperative at induction Un-cooperative at induction Extent of surgery (n) Ant. extractions only Post. extractions only Both ant.and post.extractions Duration of surgery (min) Duration of anaesthesia (min)
Sevoflurane (n:50)
Halothane (n:50)
5 (2–11.5) 19 (12–48.9) 29/21 23/22/5 38 12
5 (2.3–9.7) 18 (7–42) 31/19 22/20/8 41 9
7 31 12 2.53 (0.3–9.2) 6.72 (2.5–12.8)
8 31 11 1.91 (0.4–9.9) 5.58 (2.9–13.7)
of three consultant anaesthetists with extensive experience of the technique. Anaesthesia was induced by inhalation of 50% nitrous oxide in oxygen with the selected vapour introduced in increments of 1% to a maximum of 5% halothane, and in increments of 2% to a maximum of 8% sevoflurane. The concentration of the agents was increased every 3–5 breaths or more rapidly if tolerated by the patient. Sevoflurane and halothane were administered via recently calibrated vaporizers (Blease-Datum, TEC 3 Ohmeda). The vapour was delivered by a Bain system with the anaesthetist holding the patient end of the system as close to the child’s face as possible. Fresh gas flow rates were always in excess of 200 ml kg91 min91. When the child lost consciousness, a nasal mask was applied and anaesthesia was maintained with 50% nitrous oxide in oxygen and the selected vapour. Maintenance concentrations of sevoflurane were 2–4% and 1–2 % for halothane. Anaesthetic gases were discontinued at the time of extraction of the penultimate tooth. The child was given 100% oxygen and at completion of the procedure was turned to the left lateral, head-down position. Transfer to the recovery area occurred when the patient had a patent airway, acceptable respiratory pattern and normal oxygen saturation, and any cardiac arrhythmia had resolved. ECG recordings were analysed by a physician who was unaware of the anaesthetic agent used. These were analysed over three times: induction (time from gases on to commencement of surgery), surgery (end of induction to discontinuation of nitrous oxide and anaesthetic vapour) and recovery (end of surgery to discharge from the operating theatre). Data are presented as mean (SD) or median (95% central ranges) unless otherwise stated. Statistical analyses were performed using the Mann–Whitney U test, Fisher’s exact test or the chi-square analysis, as appropriate. P:0.05 was considered statistically significant.
HEART RATE AND ARTERIAL PRESSURE
The incidence of heart rate decreasing to less than 80 beat min91 was similar in both groups (sevoflurane group 16%, halothane group 14%) and no patient required treatment. Mean maximum heart rate was significantly higher in the sevoflurane group (146 beat min91) than in the halothane group (138 beat min91) (P:0.019). It was possible to obtain systolic arterial pressure measurements before and after induction of anaesthesia in 75 patients. In the sevoflurane group there was a mean decrease of 1.6 (SD 17.7) mm Hg; in the halothane group there was a mean decrease of 9.4 (17.7) mm Hg. This difference was not statistically significant (P:0.061). ARRHYTHMIAS
All arrhythmias (table 2) The overall incidence of arrhythmia was significantly greater in the halothane group (62% vs 28%) (P:0.0005). During induction, more patients in the halothane group had arrhythmias, although this difference was not statistically significant. During surgery, 44% of patients anaesthetized with halothane had arrhythmias compared with 24% given sevoflurane (P:0.035), whereas during the initial recovery period the values were 30% and 6%, respectively (P:0.002). Supraventricular arrhythmias The incidence of premature atrial beats and AV junctional rhythm did not differ significantly between the two groups (table 3). Ventricular arrhythmias. Single premature ventricular beats (PVB) occurred in 25 patients in the halothane group and in 11
Results Data from 100 children (50 in each treatment group) were collected and analysed. Patient characteristics and clinical data, including duration of anaesthesia and surgery, and extent of surgery, were similar in the two groups (table 1). No patient was excluded during the study.
Table 2 Incidence of arrhythmia during anaesthesia
Halothane (%) Sevoflurane (%) P
Throughout Induction
Surgery
Recovery
62 28 :0.0005
44 24 0.035
30 6 0.002
20 10 0.161
282
British Journal of Anaesthesia
Table 3 Classification and incidence of arrhythmias observed. Data are number of patients in whom the arrhythmia was seen. (PVB:Premature ventricular beats)
In the halothane group two patients had episodes of PVB of more than 10 beats and one patients had three episodes of ventricular tachycardia which were self-terminating.
Sevoflurane Halothane (n:50) (n:50) P Premature atrial beats 5 AV junctional rhythm 2 Occasional PVB 11 Bigeminy 0 Episodes of PVB :10 beats 3 Episodes of PVB 910 beats 0 Ventricular tachycardia 0
7 6 25 15 11 2 1
QUALITY OF ANAESTHESIA
0.538 0.269 0.004 :0.0005 0.021 0.153 0.315
The technique did not have to be abandoned in any patient and therefore grade 3 of the complication score was not included in the statistical analysis. Induction and recovery times (table 4) The time between start of induction and loss of eyelash reflex was significantly shorter in the sevoflurane group (mean 1.5 (SD 0.6) min) compared with the halothane group (1.9 (0.5) min). However, time to insertion of the mouth prop was significantly slower after induction with sevoflurane (3.9 (1.3) min in the sevoflurane group vs 3.5 (0.7) min in the halothane group). In the recovery period, times to eye opening and discharge were similar in both groups (table 4).
patients in the sevoflurane group (P:0.004). Bigeminy occurred only in the halothane group, in 15 patients (P:0.0005). Eleven patients anaesthetized with halothane had episodes of multifocal ventricular ectopics which occurred during all three phases of anaesthesia. This arrhythmia occurred in only three patients in the sevoflurane group (P:0.021) (table 3), and in each case the episode of PVB was not longer than 4 beats. Table 4
Induction and recovery times for sevoflurane and halothane anaesthesia. Data are mean (SD)
Sevoflurane (n:50) Halothane (n:50) P
Induction (time (min) from gases on)
Recovery (time (min) from gases off )
Loss of eyelash reflex
Insertion of mouth prop
Eye opening
Fit for discharge
1.5 (0.6) 1.9 (0.5) 0.0003
3.9 (1.3) 3.5 (0.7) 0.04
7.3 (2.3) 7.8 (2.9) 0.325
23.0 (5.6) 23.2 (5.4) 0.875
Table 5 Quality of anaesthesia in the sevoflurane (Sevo.) and halothane (Hal.) groups. Data are number of patients, with complications scored 0–2 according to severity Induction
Surgery
Recovery
Complication
Grade
Sevo. (n:50)
Hal. (n:50) P
Sevo. (n:50)
Hal. (n:50) P
Sevo. (n:50)
Hal. (n:50)
Intolerance
0 1 2 0 1 2 0 1 2 0 1 2 0 1 2 0 1 2 0 1 2 0 1 2 0 1 2 0 1 2
32 15 3 43 7 0 47 3 0 47 2 1 50 0 0 49 1 0 50 0 0 41 9 0 17 29 4 — — —
36 9 5 45 4 1 49 0 1 49 0 1 50 0 0 46 3 1 49 0 1 48 2 0 17 26 7 — — —
— — — 48 2 0 50 0 0 49 1 0 50 0 0 50 0 0 49 0 1 48 1 1 45 5 0 — — —
— — — 50 0 0 50 0 0 48 1 1 50 0 0 49 1 0 49 0 1 49 1 0 43 7 0 — — —
— — — 44 6 0 50 0 0 49 0 1 48 2 0 50 0 0 50 0 0 48 0 2 23 17 10 50 0 0
— — — 46 4 0 50 0 0 50 0 0 47 3 0 50 0 0 50 0 0 50 0 0 32 14 4 49 1 0
Coughing Salivation Laryngospasm Vomiting Breath-holding SpO2 :90 Rigidity Movement Shivering
0.52 0.54 0.99 0.32 — 0.17 0.32 0.026 0.70
0.16 — 0.55 — 0.32 — 0.55 0.54
P
0.51 — 0.32 0.65 — — 0.16 0.044 0.32
Sevoflurane and halothane for dental anaesthesia in children Complications The incidences of intolerance, airway reflex responses, hypoxaemia ( SpO2 :90%), vomiting and shivering were similar between the two groups. Nine patients in the sevoflurane group demonstrated rigidity during induction compared with two in the halothane group (P:0.026), but this was not severe enough to interfere with the technique (table 5). During the recovery period, the incidence of excitatory movements on emergence was significantly higher in the sevoflurane group (P:0.038).
Discussion Inhalation anaesthesia is used widely for induction in paediatric outpatient dental surgery. Halothane is still the agent favoured by most anaesthetists in this clinical situation, but its main problems are its propensity to cause cardiac arrhythmia, and the risk, albeit rare, of fulminant hepatitis on repeated exposure. The incidence of arrhythmia in patients undergoing dental surgery during halothane anaesthesia has been reported as high (75%).8 In our study we found that 62% of patients had arrhythmias during anaesthesia with halothane compared with only 26% of patients given sevoflurane. The significance of arrhythmias during anaesthesia for oral surgery with respect to anaesthetic mortality has yet to be established. However, the incidence of unexplained deaths in dental anaesthetic mortality reports9 10 and evidence from recent coroners’ inquests suggest that they cannot be ignored. In this study the incidence of arrhythmia during induction and surgery in the halothane group was approximately double that in the group receiving sevoflurane. It was notable that during the recovery period 30% of patients given halothane had arrhythmias compared with only 6% after sevoflurane. Coplans and Curson found that more than 50% of deaths associated with dentistry occurred during the recovery period.9 Sevoflurane may offer an increased safety margin in dental anaesthesia because of its low propensity to cause arrhythmias, but also because the associated arrhythmias are predominantly supraventricular in type. Analysis of the recordings showed that ventricular arrhythmias were found almost exclusively in the group receiving halothane. While it is not known which arrhythmias associated with anaesthesia are significant, it is generally accepted that arrhythmias which are ventricular in origin carry a higher risk. The incidence of arrhythmia in association with oral surgery was found to be much lower when enflurane (10%) and isoflurane (14%) were used.5 6 As with sevoflurane, ventricular ectopy was almost uniformly absent, but neither enflurane nor isoflurane offered equivalence in terms of facility of induction to halothane. We found that sevoflurane and halothane were similar in terms of “smoothness” and quality of anaesthesia overall. The higher incidence of rigidity during induction with sevoflurane was not severe enough to interfere with anaesthesia. Excitatory phenomena during this phase have been reported
283 previously with this agent.4 11 12 Agitation and restlessness during recovery were also more frequent after sevoflurane and were noted by other investigators.1 13 The most likely explanation is that patients are experiencing rapid emergence as the agent is eliminated rapidly. In view of the lower blood-gas partition coefficient of sevoflurane, it would be expected to provide more rapid inhalation induction than halothane.13–15 However, the rate of inhalation induction of anaesthesia is also determined by potency, maximum deliverable inspired concentration (limited by the vaporizer used) and the rate of increase of the inspired concentration. In our study no attempt was made to match the two groups in terms of equivalent MAC multiples of the volatile agents during induction, as in several recent comparative studies.1 14 16 17 Within the confines of our study we confirmed that the time to loss of the eyelash reflex was indeed shorter with sevoflurane, but the time required to achieve the depth of anaesthesia that would allow insertion of a mouth prop was marginally, but significantly, longer compared with halothane. Black and co-workers15 recently compared induction times in paediatric patients using a method similar to that described in this study and still found a shorter induction time with sevoflurane than with halothane. However, the end-point for completion of induction was the time to steady spontaneous ventilation with small pupils and central gaze. We found that these criteria did not always correspond to a plane of anaesthesia deep enough to allow insertion of a mouth prop for dental surgery. Furthermore, Sarner and colleagues4 recently compared times to intubation during sevoflurane and halothane anaesthesia and showed that the two were almost identical. It seems that while induction of anaesthesia is more rapid with sevoflurane, the time needed to achieve deeper planes of anaesthesia is similar to that with halothane. The maximum concentrations of the agents that we could deliver were 5% halothane and 8% sevoflurane. In this age group, these correspond to approximately 5 MAC and 4 MAC, respectively; this suggests that part of the limitation of induction time for sevoflurane may be a function of the vaporizer. In addition, sevoflurane is more of a respiratory depressant than halothane at concentrations greater than 1.4 MAC,18 so that at deeper planes of anaesthesia uptake of the vapour may be slower than halothane and this may also make induction relatively slower. We did not find any difference in the rate of emergence and full recovery, unlike recent studies showing that recovery from sevoflurane anaesthesia was more rapid, as would be expected from its lower blood-gas solubility.14 17 19 However, the duration of anaesthesia required for outpatient dental surgery is very short and in these circumstances halothane would not be expected to have a prolonged recovery period.
Acknowledgements We thank Dr F. M. Pereira, Department of Epidemiology and Medical Statistics, St Bartholomew’s and the Royal London School of Medicine and Dentistry for statistical analysis, and Abbott Laboratories Ltd for financial support and supplies of sevoflurane.
284
British Journal of Anaesthesia
References 1. Johannesson GP, Floren M, Lindahl SG. Sevoflurane for ENT-surgery in children. A comparison with halothane. Acta Anaesthesiologica Scandinavica 1995; 39: 546–550. 2. Epstein RH, Mendel HG, Guarnieri KM, Staudt, SR, Lessin JB, Marr AT. Sevoflurane versus halothane for general anesthesia in pediatric patients: a comparative study of vital signs, induction, and emergence. Journal of Clinical Anesthesia 1995; 7: 237–244. 3. Kawana S, Wachi J, Nakayama M, Namiki A. Comparison of haemodynamic changes induced by sevoflurane and halothane in paediatric patients. Canadian Journal of Anaesthesia 1995; 42: 603–607. 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. Ryder W, Wright PA. Halothane and enflurane in dental anaesthesia. Anaesthesia 1981; 36: 492–497. 6. Cattermole RW, Verghese C, Blair IJ, Jones CJ, Flynn PJ, Sebel PS. Isoflurane and halothane for outpatient dental anaesthesia in children. British Journal of Anaesthesia 1986; 58: 385–389. 7. McAteer PM, Carter JA, Cooper GM, Prys-Roberts C. Comparison of isoflurane and halothane in outpatient paediatric dental anaesthesia. British Journal of Anaesthesia 1986; 58: 390–393. 8. Alexander JP. Dysrhythmia and oral surgery. British Journal of Anaesthesia 1971; 43: 773–777. 9. Coplans MP, Curson I. Deaths associated with dentistry. British Dental Journal 1982; 153: 357–362. 10. Coplans MP, Curson I. Deaths associated with dentistry and dental disease 1980–1989. Anaesthesia 1993; 48: 435–438.
11. Lerman J, Sikich N, Kleinman S, Yentis S. The pharmacology of sevoflurane in infants and children. Anesthesiology 1994; 80: 814–824. 12. Adachi M, Ikemoto Y, Kubo K, Takuma C. Seizure-like movements during induction of anaesthesia with sevoflurane. British Journal of Anaesthesia 1992; 68: 214–215. 13. Lerman J, Davis PJ, Welborn LG, Orr RJ, Rabb M, Carpenter MB, Motoyama E, Hannallah R, Haberkern CM. Induction, recovery, and safety characteristics of sevoflurane in children undergoing ambulatory surgery. A comparison with halothane. Anesthesiology 1996; 84: 1332–1340. 14. Meretoja OA, Taivanen T, Raiha L, Korpela R, Wirtavuori K. Sevoflurane–nitrous oxide or halothane–nitrous oxide for paediatric bronchoscopy and gastroscopy. British Journal of Anaesthesia 1996; 76: 767–771. 15. Black A, Sury MRJ, Hemington L, Howard R, Mackersie A, Hatch DJ. A comparison of the induction characteristics of sevoflurane and halothane in children. Anaesthesia 1996; 51: 539–542. 16. 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. British Journal of Anaesthesia 1994; 73: 590–595. 17. Naito Y, Tamai S, Shingu K, Fujimori R, Mori K. Comparison between sevoflurane and halothane for paediatric ambulatory anaesthesia. British Journal of Anaesthesia 1991; 67: 387–389. 18. Doi M, Ikeda K. Respiratory effects of sevoflurane. Anesthesia and Analgesia 1987; 66: 241–244. 19. Sury MRJ, Black A, Hemington L, Howard R, Hatch DJ, Mackersie A. A comparison of the recovery characteristics of sevoflurane and halothane in children. Anaesthesia 1996; 51: 543–546.
Comparison of sevoflurane and halothane for outpatient dental anaesthesia in children
S. T. PARIS, M. CAFFERKEY, M. TARLING, P. HANCOCK, P. M. YATE AND P. J. FLYNN
Summary In a prospective, randomized, double-blind clinical study, we have studied 100 children, aged 2–12 yr, to compare halothane and sevoflurane in outpatient dental anaesthesia. All patients were unpremedicated and received inhalation induction using nitrous oxide in oxygen supplemented with either halothane (maximum inspired concentration 5%) or sevoflurane (maximum inspired concentration 8%). Time to loss of the eyelash reflex was more rapid using sevoflurane although time to adequate anaesthesia (to allow insertion of a mouth prop) was slower in the sevoflurane group. The incidence of cardiac arrhythmia was higher during halothane (62%) than during sevoflurane anaesthesia (28%) (P:0.005) and the arrhythmias were more often ventricular in origin. The two agents were comparable in terms of ease of use and quality of anaesthesia, and times to eye opening and satisfying discharge criteria were similar. We conclude that sevoflurane has qualities that have made halothane the most used inhalation agent for children, and that it is superior to halothane in dental outpatients where cardiac arrhythmias are a particular problem. (Br. J. Anaesth. 1997; 79: 280–284). Key words Anaesthetics volatile, halothane. sevoflurane. Surgery, dental. Children.
Anaesthetics
volatile,
It is becoming increasingly apparent that sevoflurane has the potential to be the inhalation induction agent of choice in children.1–4 It is relatively pleasant smelling, non-irritant and has a rapid onset and offset of action by virtue of its low blood-gas solubility. Halothane is still used widely in paediatric dental outpatient anaesthesia as it is relatively non-pungent and provides smooth induction and recovery. Its main disadvantages are a strong odour, cardiovascular depression, a propensity to cause arrhythmias and rarely hepatic necrosis, especially after repeated exposures. During dental surgery, the incidence of arrhythmia during halothane anaesthesia has been reported to be as high as 75%.5 The use of enflurane or isoflurane reduces the incidence of arrhythmias during oral surgery but both are inferior to halothane in terms of ease of induction
and quality of anaesthesia.5–7 This study was designed to compare the incidence and type of arrhythmia, and quality of anaesthesia and recovery during sevoflurane and halothane anaesthesia in children undergoing outpatient dental extraction.
Patients and methods After obtaining Ethics Committee approval and written parental consent, we studied 100 unpremedicated children, ASA I–II, aged 2–12 yr, undergoing outpatient dental extractions under general anaesthesia; patients were allocated randomly to one of two groups to receive either sevoflurane or halothane. Electrocardiographic limb leads were attached to the patient before induction of anaesthesia and a continuous record of lead II was obtained together with a visual oscilloscope display. A paediatric pulse oximetry probe was applied before induction of anaesthesia and oxygen saturation (SpO2 ) was monitored continuously throughout surgery and during recovery from anaesthesia. Arterial pressure readings before and after induction were obtained whenever possible and recorded. The time of induction, placement of the mouth prop, dental extractions and discontinuation of anaesthetic were recorded by a blinded observer who also assessed the incidence of complications during anaesthesia and recovery. Complications were graded on a scale from 0 to 3: 0:not present; 1:present but not troublesome; 2:causing interference with technique or requiring treatment; 3:so troublesome that technique had to be abandoned or patient needed admission to hospital. Complications assessed were intolerance to the vapour, breath-holding, coughing, salivation, laryngospasm, vomiting, SpO2 :90%, rigidity, excitatory movements and shivering. In the recovery area, times to eye opening to command and to “street fitness” (able to drink and walk around the recovery area unaided) were also recorded. Dental extractions were carried out in the supine position and anaesthesia was administered by one
S. T. PARIS, BSC, MB, BS, FRCA, M. TARLING, SRN, BSC, MSC, P. HANCOCK, BSC, P. J. FLYNN, MB, BCH, FFARCSI, FRCA (Anaesthetics Unit); M. CAFFERKEY, MB, CHB, MRCP (Department of Medicine); P. M. YATE, MB, FRCA (Anaesthetics Department); Royal Hospitals NHS Trust, Whitechapel, London E1 1BB. Accepted for publication: April 3, 1997.
Sevoflurane and halothane for dental anaesthesia in children Table 1
281
Patient characteristics and clinical data (median (95% central range) or number of patients)
Age (yr) Weight (kg) Sex (M/F) Race (Asian /Caucasian /Negroid) Cooperative at induction Un-cooperative at induction Extent of surgery (n) Ant. extractions only Post. extractions only Both ant.and post.extractions Duration of surgery (min) Duration of anaesthesia (min)
Sevoflurane (n:50)
Halothane (n:50)
5 (2–11.5) 19 (12–48.9) 29/21 23/22/5 38 12
5 (2.3–9.7) 18 (7–42) 31/19 22/20/8 41 9
7 31 12 2.53 (0.3–9.2) 6.72 (2.5–12.8)
8 31 11 1.91 (0.4–9.9) 5.58 (2.9–13.7)
of three consultant anaesthetists with extensive experience of the technique. Anaesthesia was induced by inhalation of 50% nitrous oxide in oxygen with the selected vapour introduced in increments of 1% to a maximum of 5% halothane, and in increments of 2% to a maximum of 8% sevoflurane. The concentration of the agents was increased every 3–5 breaths or more rapidly if tolerated by the patient. Sevoflurane and halothane were administered via recently calibrated vaporizers (Blease-Datum, TEC 3 Ohmeda). The vapour was delivered by a Bain system with the anaesthetist holding the patient end of the system as close to the child’s face as possible. Fresh gas flow rates were always in excess of 200 ml kg91 min91. When the child lost consciousness, a nasal mask was applied and anaesthesia was maintained with 50% nitrous oxide in oxygen and the selected vapour. Maintenance concentrations of sevoflurane were 2–4% and 1–2 % for halothane. Anaesthetic gases were discontinued at the time of extraction of the penultimate tooth. The child was given 100% oxygen and at completion of the procedure was turned to the left lateral, head-down position. Transfer to the recovery area occurred when the patient had a patent airway, acceptable respiratory pattern and normal oxygen saturation, and any cardiac arrhythmia had resolved. ECG recordings were analysed by a physician who was unaware of the anaesthetic agent used. These were analysed over three times: induction (time from gases on to commencement of surgery), surgery (end of induction to discontinuation of nitrous oxide and anaesthetic vapour) and recovery (end of surgery to discharge from the operating theatre). Data are presented as mean (SD) or median (95% central ranges) unless otherwise stated. Statistical analyses were performed using the Mann–Whitney U test, Fisher’s exact test or the chi-square analysis, as appropriate. P:0.05 was considered statistically significant.
HEART RATE AND ARTERIAL PRESSURE
The incidence of heart rate decreasing to less than 80 beat min91 was similar in both groups (sevoflurane group 16%, halothane group 14%) and no patient required treatment. Mean maximum heart rate was significantly higher in the sevoflurane group (146 beat min91) than in the halothane group (138 beat min91) (P:0.019). It was possible to obtain systolic arterial pressure measurements before and after induction of anaesthesia in 75 patients. In the sevoflurane group there was a mean decrease of 1.6 (SD 17.7) mm Hg; in the halothane group there was a mean decrease of 9.4 (17.7) mm Hg. This difference was not statistically significant (P:0.061). ARRHYTHMIAS
All arrhythmias (table 2) The overall incidence of arrhythmia was significantly greater in the halothane group (62% vs 28%) (P:0.0005). During induction, more patients in the halothane group had arrhythmias, although this difference was not statistically significant. During surgery, 44% of patients anaesthetized with halothane had arrhythmias compared with 24% given sevoflurane (P:0.035), whereas during the initial recovery period the values were 30% and 6%, respectively (P:0.002). Supraventricular arrhythmias The incidence of premature atrial beats and AV junctional rhythm did not differ significantly between the two groups (table 3). Ventricular arrhythmias. Single premature ventricular beats (PVB) occurred in 25 patients in the halothane group and in 11
Results Data from 100 children (50 in each treatment group) were collected and analysed. Patient characteristics and clinical data, including duration of anaesthesia and surgery, and extent of surgery, were similar in the two groups (table 1). No patient was excluded during the study.
Table 2 Incidence of arrhythmia during anaesthesia
Halothane (%) Sevoflurane (%) P
Throughout Induction
Surgery
Recovery
62 28 :0.0005
44 24 0.035
30 6 0.002
20 10 0.161
282
British Journal of Anaesthesia
Table 3 Classification and incidence of arrhythmias observed. Data are number of patients in whom the arrhythmia was seen. (PVB:Premature ventricular beats)
In the halothane group two patients had episodes of PVB of more than 10 beats and one patients had three episodes of ventricular tachycardia which were self-terminating.
Sevoflurane Halothane (n:50) (n:50) P Premature atrial beats 5 AV junctional rhythm 2 Occasional PVB 11 Bigeminy 0 Episodes of PVB :10 beats 3 Episodes of PVB 910 beats 0 Ventricular tachycardia 0
7 6 25 15 11 2 1
QUALITY OF ANAESTHESIA
0.538 0.269 0.004 :0.0005 0.021 0.153 0.315
The technique did not have to be abandoned in any patient and therefore grade 3 of the complication score was not included in the statistical analysis. Induction and recovery times (table 4) The time between start of induction and loss of eyelash reflex was significantly shorter in the sevoflurane group (mean 1.5 (SD 0.6) min) compared with the halothane group (1.9 (0.5) min). However, time to insertion of the mouth prop was significantly slower after induction with sevoflurane (3.9 (1.3) min in the sevoflurane group vs 3.5 (0.7) min in the halothane group). In the recovery period, times to eye opening and discharge were similar in both groups (table 4).
patients in the sevoflurane group (P:0.004). Bigeminy occurred only in the halothane group, in 15 patients (P:0.0005). Eleven patients anaesthetized with halothane had episodes of multifocal ventricular ectopics which occurred during all three phases of anaesthesia. This arrhythmia occurred in only three patients in the sevoflurane group (P:0.021) (table 3), and in each case the episode of PVB was not longer than 4 beats. Table 4
Induction and recovery times for sevoflurane and halothane anaesthesia. Data are mean (SD)
Sevoflurane (n:50) Halothane (n:50) P
Induction (time (min) from gases on)
Recovery (time (min) from gases off )
Loss of eyelash reflex
Insertion of mouth prop
Eye opening
Fit for discharge
1.5 (0.6) 1.9 (0.5) 0.0003
3.9 (1.3) 3.5 (0.7) 0.04
7.3 (2.3) 7.8 (2.9) 0.325
23.0 (5.6) 23.2 (5.4) 0.875
Table 5 Quality of anaesthesia in the sevoflurane (Sevo.) and halothane (Hal.) groups. Data are number of patients, with complications scored 0–2 according to severity Induction
Surgery
Recovery
Complication
Grade
Sevo. (n:50)
Hal. (n:50) P
Sevo. (n:50)
Hal. (n:50) P
Sevo. (n:50)
Hal. (n:50)
Intolerance
0 1 2 0 1 2 0 1 2 0 1 2 0 1 2 0 1 2 0 1 2 0 1 2 0 1 2 0 1 2
32 15 3 43 7 0 47 3 0 47 2 1 50 0 0 49 1 0 50 0 0 41 9 0 17 29 4 — — —
36 9 5 45 4 1 49 0 1 49 0 1 50 0 0 46 3 1 49 0 1 48 2 0 17 26 7 — — —
— — — 48 2 0 50 0 0 49 1 0 50 0 0 50 0 0 49 0 1 48 1 1 45 5 0 — — —
— — — 50 0 0 50 0 0 48 1 1 50 0 0 49 1 0 49 0 1 49 1 0 43 7 0 — — —
— — — 44 6 0 50 0 0 49 0 1 48 2 0 50 0 0 50 0 0 48 0 2 23 17 10 50 0 0
— — — 46 4 0 50 0 0 50 0 0 47 3 0 50 0 0 50 0 0 50 0 0 32 14 4 49 1 0
Coughing Salivation Laryngospasm Vomiting Breath-holding SpO2 :90 Rigidity Movement Shivering
0.52 0.54 0.99 0.32 — 0.17 0.32 0.026 0.70
0.16 — 0.55 — 0.32 — 0.55 0.54
P
0.51 — 0.32 0.65 — — 0.16 0.044 0.32
Sevoflurane and halothane for dental anaesthesia in children Complications The incidences of intolerance, airway reflex responses, hypoxaemia ( SpO2 :90%), vomiting and shivering were similar between the two groups. Nine patients in the sevoflurane group demonstrated rigidity during induction compared with two in the halothane group (P:0.026), but this was not severe enough to interfere with the technique (table 5). During the recovery period, the incidence of excitatory movements on emergence was significantly higher in the sevoflurane group (P:0.038).
Discussion Inhalation anaesthesia is used widely for induction in paediatric outpatient dental surgery. Halothane is still the agent favoured by most anaesthetists in this clinical situation, but its main problems are its propensity to cause cardiac arrhythmia, and the risk, albeit rare, of fulminant hepatitis on repeated exposure. The incidence of arrhythmia in patients undergoing dental surgery during halothane anaesthesia has been reported as high (75%).8 In our study we found that 62% of patients had arrhythmias during anaesthesia with halothane compared with only 26% of patients given sevoflurane. The significance of arrhythmias during anaesthesia for oral surgery with respect to anaesthetic mortality has yet to be established. However, the incidence of unexplained deaths in dental anaesthetic mortality reports9 10 and evidence from recent coroners’ inquests suggest that they cannot be ignored. In this study the incidence of arrhythmia during induction and surgery in the halothane group was approximately double that in the group receiving sevoflurane. It was notable that during the recovery period 30% of patients given halothane had arrhythmias compared with only 6% after sevoflurane. Coplans and Curson found that more than 50% of deaths associated with dentistry occurred during the recovery period.9 Sevoflurane may offer an increased safety margin in dental anaesthesia because of its low propensity to cause arrhythmias, but also because the associated arrhythmias are predominantly supraventricular in type. Analysis of the recordings showed that ventricular arrhythmias were found almost exclusively in the group receiving halothane. While it is not known which arrhythmias associated with anaesthesia are significant, it is generally accepted that arrhythmias which are ventricular in origin carry a higher risk. The incidence of arrhythmia in association with oral surgery was found to be much lower when enflurane (10%) and isoflurane (14%) were used.5 6 As with sevoflurane, ventricular ectopy was almost uniformly absent, but neither enflurane nor isoflurane offered equivalence in terms of facility of induction to halothane. We found that sevoflurane and halothane were similar in terms of “smoothness” and quality of anaesthesia overall. The higher incidence of rigidity during induction with sevoflurane was not severe enough to interfere with anaesthesia. Excitatory phenomena during this phase have been reported
283 previously with this agent.4 11 12 Agitation and restlessness during recovery were also more frequent after sevoflurane and were noted by other investigators.1 13 The most likely explanation is that patients are experiencing rapid emergence as the agent is eliminated rapidly. In view of the lower blood-gas partition coefficient of sevoflurane, it would be expected to provide more rapid inhalation induction than halothane.13–15 However, the rate of inhalation induction of anaesthesia is also determined by potency, maximum deliverable inspired concentration (limited by the vaporizer used) and the rate of increase of the inspired concentration. In our study no attempt was made to match the two groups in terms of equivalent MAC multiples of the volatile agents during induction, as in several recent comparative studies.1 14 16 17 Within the confines of our study we confirmed that the time to loss of the eyelash reflex was indeed shorter with sevoflurane, but the time required to achieve the depth of anaesthesia that would allow insertion of a mouth prop was marginally, but significantly, longer compared with halothane. Black and co-workers15 recently compared induction times in paediatric patients using a method similar to that described in this study and still found a shorter induction time with sevoflurane than with halothane. However, the end-point for completion of induction was the time to steady spontaneous ventilation with small pupils and central gaze. We found that these criteria did not always correspond to a plane of anaesthesia deep enough to allow insertion of a mouth prop for dental surgery. Furthermore, Sarner and colleagues4 recently compared times to intubation during sevoflurane and halothane anaesthesia and showed that the two were almost identical. It seems that while induction of anaesthesia is more rapid with sevoflurane, the time needed to achieve deeper planes of anaesthesia is similar to that with halothane. The maximum concentrations of the agents that we could deliver were 5% halothane and 8% sevoflurane. In this age group, these correspond to approximately 5 MAC and 4 MAC, respectively; this suggests that part of the limitation of induction time for sevoflurane may be a function of the vaporizer. In addition, sevoflurane is more of a respiratory depressant than halothane at concentrations greater than 1.4 MAC,18 so that at deeper planes of anaesthesia uptake of the vapour may be slower than halothane and this may also make induction relatively slower. We did not find any difference in the rate of emergence and full recovery, unlike recent studies showing that recovery from sevoflurane anaesthesia was more rapid, as would be expected from its lower blood-gas solubility.14 17 19 However, the duration of anaesthesia required for outpatient dental surgery is very short and in these circumstances halothane would not be expected to have a prolonged recovery period.
Acknowledgements We thank Dr F. M. Pereira, Department of Epidemiology and Medical Statistics, St Bartholomew’s and the Royal London School of Medicine and Dentistry for statistical analysis, and Abbott Laboratories Ltd for financial support and supplies of sevoflurane.
284
British Journal of Anaesthesia
References 1. Johannesson GP, Floren M, Lindahl SG. Sevoflurane for ENT-surgery in children. A comparison with halothane. Acta Anaesthesiologica Scandinavica 1995; 39: 546–550. 2. Epstein RH, Mendel HG, Guarnieri KM, Staudt, SR, Lessin JB, Marr AT. Sevoflurane versus halothane for general anesthesia in pediatric patients: a comparative study of vital signs, induction, and emergence. Journal of Clinical Anesthesia 1995; 7: 237–244. 3. Kawana S, Wachi J, Nakayama M, Namiki A. Comparison of haemodynamic changes induced by sevoflurane and halothane in paediatric patients. Canadian Journal of Anaesthesia 1995; 42: 603–607. 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. Ryder W, Wright PA. Halothane and enflurane in dental anaesthesia. Anaesthesia 1981; 36: 492–497. 6. Cattermole RW, Verghese C, Blair IJ, Jones CJ, Flynn PJ, Sebel PS. Isoflurane and halothane for outpatient dental anaesthesia in children. British Journal of Anaesthesia 1986; 58: 385–389. 7. McAteer PM, Carter JA, Cooper GM, Prys-Roberts C. Comparison of isoflurane and halothane in outpatient paediatric dental anaesthesia. British Journal of Anaesthesia 1986; 58: 390–393. 8. Alexander JP. Dysrhythmia and oral surgery. British Journal of Anaesthesia 1971; 43: 773–777. 9. Coplans MP, Curson I. Deaths associated with dentistry. British Dental Journal 1982; 153: 357–362. 10. Coplans MP, Curson I. Deaths associated with dentistry and dental disease 1980–1989. Anaesthesia 1993; 48: 435–438.
11. Lerman J, Sikich N, Kleinman S, Yentis S. The pharmacology of sevoflurane in infants and children. Anesthesiology 1994; 80: 814–824. 12. Adachi M, Ikemoto Y, Kubo K, Takuma C. Seizure-like movements during induction of anaesthesia with sevoflurane. British Journal of Anaesthesia 1992; 68: 214–215. 13. Lerman J, Davis PJ, Welborn LG, Orr RJ, Rabb M, Carpenter MB, Motoyama E, Hannallah R, Haberkern CM. Induction, recovery, and safety characteristics of sevoflurane in children undergoing ambulatory surgery. A comparison with halothane. Anesthesiology 1996; 84: 1332–1340. 14. Meretoja OA, Taivanen T, Raiha L, Korpela R, Wirtavuori K. Sevoflurane–nitrous oxide or halothane–nitrous oxide for paediatric bronchoscopy and gastroscopy. British Journal of Anaesthesia 1996; 76: 767–771. 15. Black A, Sury MRJ, Hemington L, Howard R, Mackersie A, Hatch DJ. A comparison of the induction characteristics of sevoflurane and halothane in children. Anaesthesia 1996; 51: 539–542. 16. 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. British Journal of Anaesthesia 1994; 73: 590–595. 17. Naito Y, Tamai S, Shingu K, Fujimori R, Mori K. Comparison between sevoflurane and halothane for paediatric ambulatory anaesthesia. British Journal of Anaesthesia 1991; 67: 387–389. 18. Doi M, Ikeda K. Respiratory effects of sevoflurane. Anesthesia and Analgesia 1987; 66: 241–244. 19. Sury MRJ, Black A, Hemington L, Howard R, Hatch DJ, Mackersie A. A comparison of the recovery characteristics of sevoflurane and halothane in children. Anaesthesia 1996; 51: 543–546.