BJA Advance Access originally published online on June 6, 2007
British Journal of Anaesthesia 2007 99(2):262-265; doi:10.1093/bja/aem145
Comparison of desflurane with sevoflurane for the incidence of oculocardiac reflex in children undergoing strabismus surgery
1 Department of Anaesthesiology and Pain Medicine, Seoul National University Bundang Hospital, Republic of Korea
2 Department of Anaesthesiology, Seoul National University College of Medicine, 28 Yeongun-Dong, Chongro-Gu, Seoul 110-744, Republic of Korea
* Corresponding author. E-mail: dami0605{at}snu.ac.kr
Accepted for publication April 18, 2007.
 |
Abstract |
|---|
 Top Abstract IntroductionMethodsResultsDiscussionReferences |
|---|
Background: The oculocardiac reflex (OCR) is frequently observed during strabismus surgery. This study was designed to evaluate and compare the effect of sevoflurane and desflurane on the incidence of OCR.
Methods: After obtaining Institutional Review Board approval and informed consent from parents, we enrolled 237 paediatric patients, aged 2–10 yr, undergoing strabismus surgery. No premedication was given. Anaesthesia was induced with thiopental and rocuronium. Patients were randomly allocated to one of the two anaesthetic regimens. Group S (n = 123) received sevoflurane and Group D (n = 114) received desflurane, both with 60% N2O/O2 for maintenance of anaesthesia. The OCR was defined as a 
20% decrease in heart rate (HR) from baseline values obtained immediately before muscle manipulation. If the HR did not increase after release of muscle tension, atropine 0.01 mg kg–1 was administered.
Results: There were no significant differences between the two groups in age, sex, body weight, and the number of muscles operated upon. The mean values of baseline HR were 123 (16) min–1 in Group S and 121 (18) in Group D (NS). The minimum HR was 106 (22) min–1 in Group S and 103 (21) in Group D (NS). There was no difference in the incidence of OCR between sevoflurane (26.0%) and desflurane (28.0%) anaesthesia.
Conclusions: Both agents can be used safely during strabismus surgery in paediatric patients.
Keywords: anaesthetics volatile, desflurane; anaesthetics volatile, sevoflurane; children; strabismus
|
Introduction |
|---|
|
TopAbstractIntroductionMethodsResultsDiscussionReferences |
|---|
The oculocardiac reflex (OCR) is triggered by pressure on the globe, conjunctiva and orbital structures, and traction on the extraocular muscles. The afferent limb consists of the trigeminal nerve and the efferent limb is the vagal nerve. Hence, the OCR is also known as the trigemino-vagal reflex. The most common manifestation is sinus bradycardia, although many different cardiac dysrhythmias may occur.1
The incidence of the OCR during strabismus has been variously reported as 14% to 90%, depending on the anaesthetic agent, premedication, and the definition of OCR used. Studies demonstrate a higher incidence in children who tend to have more vagal tone.2–4
Sevoflurane is associated with a lower incidence of OCR than halothane or propofol,5 but desflurane has not been studied in comparison with other agents. As it increases sympathetic activity and heart rate (HR) in a concentration-dependent manner, we hypothesized that its use should be associated with a relatively low incidence of OCR. The aim of the present study was to evaluate the incidence of OCR during desflurane anaesthesia and compare it with that during sevoflurane anaesthesia in children undergoing strabismus surgery.
|
Methods |
|---|
|
TopAbstractIntroductionMethodsResultsDiscussionReferences |
|---|
After Institutional Review Board approval and informed consent from the parents, 237 ASA class I paediatric patients, aged between 2 and 10 yr undergoing strabismus surgery, were enrolled. Patients with cardiovascular disease or who had taken cardiovascular drugs were excluded.
The study was designed as an open, randomized study. Subjects were randomly assigned by computer-generated random numbers to be maintained with either sevoflurane (Group S) or desflurane (Group D). All patients were unpremedicated and were induced with i.v. thiopental 5 mg kg–1 during preoxygenation with O2 100%, via facial mask. After confirming the loss of consciousness, assisted ventilation with sevoflurane 8% in Group S and desflurane 2% in Group D, both in N2O 60%, was started. In Group D, the concentration of desflurane was increased gradually by 2% per two to three breaths until 12–15% was reached. Rocuronium 0.4 mg kg–1 was injected immediately after the start of assisted ventilation, and the trachea was intubated after confirmation of neuromuscular block with a nerve stimulator. Monitoring consisted of ECG, NIBP, pulse oximetry, temperature, and capnography. The lungs were mechanically ventilated and ventilation was adjusted to achieve an end-tidal carbon dioxide concentration of 30–35 mm Hg. A fresh gas flow of 3 litre min–1 was used in a circular system. Anaesthesia was maintained with 1–1.2 MAC of sevoflurane or desflurane and 60% nitrous oxide in oxygen according to arterial pressure and HR, which were maintained within 20% of preoperative values. To provide 1.0 MAC, the vaporizer was set at 2.5% for all patients in Group S,6 and in Group D at 8.7% for those aged 2–3 yr, and 8.0% for those aged 4–10 yr.7 The MAC-reducing effect in children of N2O 60% is similar in the two agents, at about 25%.6 8 The anaesthetic effect should thus be about 1.3–1.5 MAC. An equilibration period of at least 30 min was allowed for washout of thiopental and tissue saturation with the anaesthetic gas.
The OCR was defined as a 20% decrease in HR from baseline values obtained immediately before muscle manipulation. Treatment of OCR consisted of relief of traction. If the HR still did not return to baseline values or severe bradycardia (HR < 60 min–1) developed, i.v. atropine 0.01 mg kg–1 was administered.
Statistical analysis
On the basis of the estimated incidence of 50% in Group S, a priori power analysis indicated that 101 patients per group would be sufficient to detect a difference in the incidence of OCR of 20% with a power greater than 90% at the significance level of 0.05. Data are expressed as median (range), mean (SD), and number (% incidence). The differences between the groups were tested using Student's t-test and 
2 test as appropriate. All P-values are two-sided and are considered significant at P < 0.05.
|
Results |
|---|
|
TopAbstractIntroductionMethodsResultsDiscussionReferences |
|---|
Patient characteristics are given in Table 1. There were no significant differences regarding sex, age, body weight, or number of muscles operated. OCR was seen in 26.0% (32/123) of patients in Group S and 28.0% (32/114) in Group D (NS:
2=0.127, P = 0.71). The lowest HR during muscle manipulation was 50 min–1 (52% reduction from baseline, in an 8-yr-old girl) in Group S and 55 min–1 (55% reduction from baseline, in a 9-yr-old boy) in Group D. The mean baseline HR was 123 (16) min–1 in Group S and 121 (18) min–1 in Group D. The mean minimum HR was 106 (22) min–1 in Group S and 103 (21) in Group D (NS: Table 2).
|
|
When the patients were divided into two age groups (2–5 and 6–10 yr), baseline HR were significantly decreased as age increased and the incidence of OCR was significantly lower in 2–5 yr group compared with the 6–10 yr group (Table 3).
|
In most patients demonstrating OCR, HR returned to baseline value after release of the muscle and only two patients (discussed earlier) needed atropine as treatment due to severe bradycardia (<60 min–1). There were no other clinically significant arrhythmias. Arterial pressure was maintained within 20% of preoperative values.
|
Discussion |
|---|
|
TopAbstractIntroductionMethodsResultsDiscussionReferences |
|---|
Because desflurane increases sympathetic activity, we hypothesized that the incidence of OCR during paediatric strabismus surgery under general anaesthesia would be lower with desflurane than with sevoflurane. However, our study found no difference between the two agents.
Anticholinergic prophylaxis decreases the incidence of OCR.9–11 However, atropine may cause bigeminy and increase ectopic beats and these arrhythmias are more persistent than the OCR.12 It is known that an intrinsic counter-regulatory process exists to restore the HR during the constant pressure on the eyeball or traction of the external eye muscles. This phenomenon is also named ‘vagal escape’ or ‘OCR fatigue’.13 14 The use of atropine as the treatment of bradycardia is still controversial due to its latency.13 Gentle surgical manipulations are most important for prophylaxis and once the severe bradycardia develops, it must be treated by releasing the traction. Most of our patients studied here, including those who showed OCR, underwent surgery without significant haemodynamic derangements without the use of atropine.
Inhalation anaesthetics decrease HR in the isolated heart but mostly increase it in vivo,15 16 and the differences between agents in this regard are explained by differences in their vagolytic action.16 In contrast to other agents, desflurane is the only agent which invariably increases sympathetic activity, which contributes to the increase in HR.17 It is a pungent gas, and the increased sympathetic outflow is believed to be the result from stimulation of receptors in or near the airways, rather than by baroreceptor desensitization,17 18 which is most marked when the concentration is rapidly increased. However, increased sympathetic outflow seems to play only a minor role in the increase of HR during steady-state anaesthesia with desflurane, during which the main factor is, as with other inhalation anaesthetics, vagal inhibition.19 We recorded the baseline HR just before traction on the muscle, by which steady-state conditions should have been achieved, and sympathetic effects on the heart should by then have been minimal. The major influence on the incidence of OCR would be the vagolytic effect of desflurane. Cardiac vagal activity, measured by HR variability, is least with desflurane and sevoflurane, intermediate with isoflurane and enflurane, and greatest with halothane.16 The vagolytic effects of sevoflurane and desflurane are equal, hereby perhaps explaining the similar incidence of OCR in the two study groups.
Our results also show that among the children aged 2–10 yr, the incidence of OCR is lower in the 2–5 yr age group compared with the 6–10 yr age group. The spectral analysis of HR variability has shown that parasympathetic activity increases from 3 to 6 yr of age and then decreases from 6 to 15 yr of age in healthy children.20 Already increased parasympathetic activities might have a relationship with the lower incidence of OCR in younger age group in our study.
The limitation of our study is that we did not measure the end-tidal concentration of anaesthetic agent; we only controlled the inhaled concentration. The end-tidal concentration may thus be lower than the intended 1.3–1.5 MAC of anaesthetic concentration, and we may not have achieved equivalent levels of MAC with the two agents. Another limitation is that we simply observed HR as the definition of OCR. Although the most common manifestation of the OCR is sinus bradycardia, a wide spectrum of cardiac dysrhythmias may occur, including junctional rhythm, atrioventricular blockade, atrial or ventricular premature beats, and even asystole.2 21 However, Allison and colleagues22 reported that the incidence of arrhythmia during strabismus surgery with sevoflurane was only 4%, whereas that with halothane was 42%. We also noted that no patient showed significant arrhythmias, which needed treatment during the study period. It is true that we might have missed the arrhythmias but the expected incidence and clinical importance of arrhythmias are considered to be low.
In summary, the incidence of OCR during anaesthesia for strabismus surgery with sevoflurane and desflurane in children were similar at 26% and 28%, respectively, and did not differ significantly. The incidence of OCR was lower in children aged 2–5 yr compared with those aged 6–10 yr. Both sevoflurane and desflurane can be used effectively and safely during strabismus surgery in paediatric patients.
|
References |
|---|
|
TopAbstractIntroductionMethodsResultsDiscussionReferences |
|---|
1 Alexander JP. Reflex disturbances of cardiac rhythm during ophthalmic surgery. Br J Ophthalmol (1975) 59:518–24.
2 McGoldrick KE, Gayer S. Anesthesia and the eye. In: Clinical Anesthesia—Barash PG, Cullen BF, Stoelting RK, eds. (2006) Philadelphia: Lippincott Williams & Wilkins. 974–96.
3 Hahnenkamp K, Honemann CW, Fischer LG, Durieux ME, Muehlendyck H, Braun U. Effect of different anaesthetic regimes on the oculocardiac reflex during paediatric strabismus surgery. Paediatr Anaesth (2000) 10:601–8.[Web of Science][Medline]
4 Goerlich TM, Foja C, Olthoff D. Effects of sevoflurane versus propofol on oculocardiac reflex—a comparative study in 180 children. Anaesthesiol Reanim (2000) 25:17–21.[Medline]
5 Gurkan Y, Kilickan L, Toker K. Propofol-nitrous oxide versus sevoflurane-nitrous oxide for strabismus surgery in children. Paediatr Anaesth (1999) 9:495–9.[CrossRef][Web of Science][Medline]
6 Lerman J, Sikich N, Kleinman S, Yentis S. The pharmacology of sevoflurane in infants and children. Anesthesiology (1994) 80:814–24.[CrossRef][Web of Science][Medline]
7 Taylor RH, Lerman J. Minimum alveolar concentration of desflurane and hemodynamic responses in neonates, infants, and children. Anesthesiology (1991) 75:975–9.[CrossRef][Web of Science][Medline]
8 Fisher DM, Zwass MS. MAC of desflurane in 60% nitrous oxide in infants and children. Anesthesiology (1992) 76:354–6.[Web of Science][Medline]
9 Tramer MR, Sansonetti A, Fuchs-Buder T, Rifat K. Oculocardiac reflex and postoperative vomiting in paediatric strabismus surgery. A randomised controlled trial comparing four anaesthetic techniques. Acta Anaesthesiol Scand (1998) 42:117–23.[Medline]
10 Klockgether-Radke A, Demmel C, Braun U, Muhlendyck H. Emesis and the oculocardiac reflex. Drug prophylaxis with droperidol and atropine in children undergoing strabismus surgery. Anaesthesist (1993) 42:356–60.[Web of Science][Medline]
11 Chisakuta AM, Mirakhur RK. Anticholinergic prophylaxis does not prevent emesis following strabismus surgery in children. Paediatr Anaesth (1995) 5:97–100.[CrossRef][Web of Science][Medline]
12 Donlon JV. Anesthesia for eye, ear, nose, and throat surgery. In: Anesthesia—Miller RD, ed. (2005) Philadelphia: Churchille Livingstone. 2527–31.
13 Braun U, Feise J, Muhlendyck H. Is there a cholinergic and an adrenergic phase of the oculocardiac reflex during strabismus surgery? Acta Anaesthesiol Scand (1993) 37:390–5.[Web of Science][Medline]
14 Moonie GT, Rees DL, Elton D. The oculocardiac reflex during strabismus surgery. Can Anaesth Soc J (1964) 11:621–32.[Medline]
15 Tanaka S, Tsuchida H, Nakabayashi K, Seki S, Namiki A. The effects of sevoflurane, isoflurane, halothane, and enflurane on hemodynamic responses during an inhaled induction of anesthesia via a mask in humans. Anesth Analg (1996) 82:821–6.[Abstract]
16 Picker O, Scheeren TW, Arndt JO. Inhalation anaesthetics increase heart rate by decreasing cardiac vagal activity in dogs. Br J Anaesth (2001) 87:748–54.
17 Ebert TJ, Perez F, Uhrich TD, Deshur MA. Desflurane-mediated sympathetic activation occurs in humans despite preventing hypotension and baroreceptor unloading. Anesthesiology (1998) 88:1227–32.[CrossRef][Web of Science][Medline]
18 Muzi M, Ebert TJ, Hope WG, Robinson BJ, Bell LB. Site(s) mediating sympathetic activation with desflurane. Anesthesiology (1996) 85:737–47.[CrossRef][Web of Science][Medline]
19 Picker O, Schwarte LA, Schindler AW, Scheeren TW. Desflurane increases heart rate independent of sympathetic activity in dogs. Eur J Anaesthesiol (2003) 20:945–51.[CrossRef][Web of Science][Medline]
20 Goto M, Nagashima M, Baba R, et al. Analysis of heart rate variability demonstrates effects of development on vagal modulation of heart rate in healthy children. J Pediatr (1997) 130:725–9.[Web of Science][Medline]
21 Gold RS, Pollard Z, Buchwald IP. Asystole due to the oculocardiac reflex during strabismus surgery: a report of two cases. Ann Ophthalmol (1988) 20:473–5. 7.[Web of Science][Medline]
22 Allison CE, De Lange JJ, Koole FD, Zuurmond WW, Ros HH, van Schagen NT. A comparison of the incidence of the oculocardiac and oculorespiratory reflexes during sevoflurane or halothane anesthesia for strabismus surgery in children. Anesth Analg (2000) 90:306–10.
CiteULike 
Connotea 
Del.icio.us What's this?
This article has been cited by other articles:
|
|
 |
|
  C. Yi and D. Jee Influence of the anaesthetic depth on the inhibition of the oculocardiac reflex during sevoflurane anaesthesia for paediatric strabismus surgery Br. J. Anaesth., August 1, 2008; 101(2): 234 - 238. [Abstract] [Full Text] [PDF]
|
|
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||