British Journal of Anaesthesia 1990; 64: 167-169
OXYGEN SATURATION DURING INHALATION INDUCTION WITH HALOTHANE AND ISOFLURANE IN CHILDREN: EFFECT OF PREMEDICATION WITH RECTAL THIOPENTONE S. RAFTERY AND D. WARDE
Anaesthesia was induced by inhalation in 100 children using nitrous oxide in oxygen supplemented by either halothane or isoflurane. with or without rectal thiopentone premedication. Respiratory problems occurred more frequently in the unpremedicated isoflurane group, resulting in significant reductions in oxygen saturation. Premedication reduced the frequency of these complications, and oxygen saturation was usually maintained. KEY WORDS Anaesthetics volatile: halothane, isoflurane. Anaesthesia: paediatric. Oxygen: saturation.
Induction of anaesthesia using an inhalation technique is appropriate in young children who may become distressed by repeated attempts at venous cannulation. Halothane is used commonly for this purpose, with induction usually being rapid and smooth [1]. However, this agent is associated with myocardial depression and arrhythmias [1, 2]. Isoflurane is metabolized to a lesser extent and tends to maintain cardiac output and rhythm [3, 4]. Two recently published studies [5, 6] have shown that isoflurane is associated with a greater incidence of hypoxia during inhalation induction of unpremedicated children compared with halothane. We wished to determine if premedication alters the incidence of respiratory complications and hypoxia during inhalation induction of anaesthesia with either of these agents. PATIENTS AND METHODS
We studied 100 healthy children weighing less than 20 kg, aged between 1 and 6 yr, who had not
been exposed to halothane within the previous 6 months. Institutional Ethics Committee approval was given for the study and informed parental consent was obtained in each case. Children were randomly allocated to one of four groups. Group NH (w = 24) received no premedication and halothane was used for induction. Group NI (M = 25) received no premedication and isoflurane. Groups TH (w = 27) and TI (n = 24) were given 40 % thiopentone suspension 30 mg kg"1 per rectum 30 min before induction with halothane or isoflurane, respectively. Premedication was administered in a paediatric surgical ward, the buttocks were taped together, and the child was transferred immediately to the adjacent theatre suite to be observed continuously by an experienced member of the nursing staff. In each patient the anaesthetic was administered by the same anaesthetist (D.W.) who had experience of use of both agents for inhalation induction in children for some years. Recordings were made by an independent observer (S.R.) who was blinded to the anaesthetic used. Before induction, each patient's sex, age, weight and demeanour were noted. Preoperative arterial oxygen saturation (5aOz) was recorded for 1 min after steady readings were obtained using a Critikon Oxyshuttle pulse oximeter probe attached to the hallux. The anaesthetist was unaware of the oximeter display and audio signals, but was informed if Sa0> decreased to less than 80 %. STEPHEN RAFTERY*, M.B., F.F.A.R.C.S.I.; DECLAN WARDE, M.B.,
F.F.A.R.C.S.I.; Department of Anaesthesia, The Children's Hospital, Temple Street, Dublin 1, Ireland. Accepted for Publication: July 3, 1989. * Present address: Department of Anaesthesia, Bristol Royal Infirmary, Bristol BS2 8HW. Correspondence to D. W.
Downloaded from http://bja.oxfordjournals.org/ at East Carolina University on July 9, 2015
SUMMARY
BRITISH JOURNAL OF ANAESTHESIA
168
TABLE I. Patient characteristics : age, weight (mean (SEM)) and sex distribution. No significant differences between groups Group NH = No premed./Halothane (n = 24) NI = No premed./Isoflurane (n = 25) TH = Thiopentone/Halothane (n = 27) TI = Thiopentone/Isoflurane (n = 24)
Age (months)
Weight (kg)
M/F
Sex
35.6 (14.8) 39.6 (15.0) 36.7(17.1) 34.5(13.8)
14.4 (3.5) 15.5 (2.3) 13.7(3.0) 14.1(2.4)
15/9 20/5 20/7 14/10
TABLE II. Preoperative demeanour and SaOl (median (range)). All differences between groups significant (P < 0.005)
Groups Unpremedicated (n = 49) Premedicated (n = 51)
Drowsy
Co-operative
Crying
Sa o (%)
0 47
27 0
22 4
99 (97-100) 97 (94-100)
Anaesthesia was induced with 60% nitrous TABLE III. Number of patients attaining various lowest oxide and the anaesthetic in oxygen. An Ayre's arterial oxygen saturations during induction. Figures in T-piece with Jackson-Rees modification was used parentheses represent the number of patients in each group (in with a fresh gas flow sufficient to prevent whom minimum saturation was within the relevant range) with rebreathing. The initial inspired concentration of airway complications. * Median Sa 0; significantly different from group NH (P < 0.05) the vapour was 0.5%, and this was increased by 0.5% every 10 breaths up to a maximum of 4%. Sa o , (%) Initially, the anaesthetic mixture was administered with the aid of a cupped hand over the Group 71 91-100 81-90 71-80 child's mouth and nose; when the eyelash reflex = 24) 20(5) had disappeared, an anaesthetic face-mask of 2(2) 15(5) 6(6) (n == 25)* 2(1) appropriate size was applied. Induction was NI 26(3) TH(« == 27) 1(1) judged to be complete when the child was 21(4) 2(2) :24) KD unconscious and breathing regularly, with eyes fixed and central, and pupils constricted. 5aOj, heart rate, inspired anaesthetic concenRESULTS tration and stage of anaesthesia were recorded every 15 s. Any events of bradycardia, struggling, The four groups were similar in age, weight and breath-holding, coughing or laryngospasm were sex distribution (table I). recorded, together with the lowest associated The premedicated children were almost all 5aOj. Time taken to induce anaesthesia was asleep or drowsy on arrival in the induction room, noted. while those unpremedicated were all either calm Parametric data (age, weight) were tested for and co-operative or crying (P < 0.005). Prestatistical significance by analysis of variance; if a medicated children had a lower SaOs than difference in the means was found, further unpremedicated (P < 0.005) (table II). Group NI analysis was carried out with Student's unpaired t children displayed lower minimum oxygen test. The Kruskal-Wallis and Wilcoxon Rank saturation than those in any of the other groups Sum tests were used for non-parametric data (P < 0.005). There was no significant difference (5aOj, induction time). The chi-square test between the other three groups with regard to with Yates' correction and Fisher's exact test were minimum SaOj (table III). used for nominal data (sex distribution, incidence Laryngospasm occurred in nine patients, all in of complications). P < 0.05 was taken as sig- group NI (P < 0.005), and in seven of these SaO! nificant. decreased to less than 91 %. Isoflurane induction
Downloaded from http://bja.oxfordjournals.org/ at East Carolina University on July 9, 2015
Demeanour
OXYGEN SATURATION AND ISOFLURANE
169
TABLE IV. Incidence (n) of complications in those children 97% or greater, 10 of the premedicated subjects whose SaOl decreased to less than 91 %, and associated median had an SaOi less than 97 %. It must be concluded, trough SaOt (in parentheses), f P < 0.05 for n, compared with therefore, that use of rectal thiopentone requires group NI. * P < 0.05 for SaOj compared with pooled groups experienced supervision and immediate availNH and TH
ability of resuscitation equipment. The major finding of our study was that premedication with rectal thiopentone reduced Event n SaOt n SaOt n SaOl n the incidence of hypoxic episodes in children in whom anaesthesia was induced with isoflurane. None 3 (86) Laryngospasm 7 (63) SaOi decreased during airway complications such Breathholding 1 (56) as laryngospasm or coughing, but in three patients Coughing 1 (89) 1 (86) 2 (64) (in group NH) hypoxia occurred in the absence of Struggling 1 (88) 2 (80) such complications. There was no significant * t t * difference in SaOi during induction between the premedicated isoflurane group and both halothane groups. The reduction in the number of TABLE V. Time taken to induce anaesthesia (median (range)).hypoxic episodes in group TI was related possibly * Median time different from group NH (P < 0.005) to the reduction in frequency of airway complications (table III). Induction time (min) Group We conclude that the frequency of hypoxia associated with inhalation induction of anaesthesia 7.25 (4.5-12) NH with isoflurane in children may be reduced by 10.25 (6.25-18) NI* premedication with rectal thiopentone, at the cost 5.5 (3.5-7.75) TH 6.75 (4.25-14.5) TI of borderline hypoxia before induction. If isoflurane is to be used for inhalation induction of anaesthesia in young children, we recommend that consideration should be given to the use of was associated with more frequent and severe sedative premedication in order to reduce the episodes of hypoxia, with concomitant laryngo- incidence of hypoxia seen with this agent. spasm, coughing or struggling. When premedication was used, these episodes were less REFERENCES frequent, but SaOz decreased to similar values 1. Pandit UA, Steude GM, Leache AB. Induction and (table IV). recovery characteristics of isoflurane and halothane anTime taken to induce anaesthesia was longer in aesthesia for short outpatient operations in children. the unpremedicated isoflurane group than the Anaesthesia 1985; 40; 1226-1230. 2. Kenna JG, Neuberger J, Mieli-Vergani G, Mowat AP, other groups (table V) (P < 0.005). NH
NI
TH
TI
Our work confirms previous findings [5, 6] demonstrating a high incidence of hypoxia during inhalation induction of anaesthesia in unpremedicated children with isoflurane, even when a slow induction technique was used by an experienced paediatric anaesthetist. The premedication regimen was effective (table II), but we were concerned to find that many of the premedicated children presented in the induction room with borderline hypoxia. While all unpremedicated children had an initial Sa o of
4.
5.
6.
Downloaded from http://bja.oxfordjournals.org/ at East Carolina University on July 9, 2015
3. DISCUSSION
Williams R. Halothane hepatitis in children. British Medical Journal 1987; 294: 1209-1210. 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. Wren WS, McShane AJ, McCarthy JG, Lamont BJ, Casey WF, Hannon VM. Isoflurane in paediatric anaesthesia. Induction and recovery from anaesthesia. Anaesthesia 1985; 40: 315-323. Phillips AJ, Brimacombe JR, Simpson DL. Anaesthetic induction with isoflurane or halothane. Oxygen saturation during induction with isoflurane or halothane in unpremedicated children. Anaesthesia 1988; 43: 927-929. Sampaio MM, Crean PM, Keilty SR, Black GW. Changes in oxygen saturation during inhalation induction of anaesthesia in children. British Journal of Anaesthesia 1989; 62: 199-201.
OXYGEN SATURATION DURING INHALATION INDUCTION WITH HALOTHANE AND ISOFLURANE IN CHILDREN: EFFECT OF PREMEDICATION WITH RECTAL THIOPENTONE S. RAFTERY AND D. WARDE
Anaesthesia was induced by inhalation in 100 children using nitrous oxide in oxygen supplemented by either halothane or isoflurane. with or without rectal thiopentone premedication. Respiratory problems occurred more frequently in the unpremedicated isoflurane group, resulting in significant reductions in oxygen saturation. Premedication reduced the frequency of these complications, and oxygen saturation was usually maintained. KEY WORDS Anaesthetics volatile: halothane, isoflurane. Anaesthesia: paediatric. Oxygen: saturation.
Induction of anaesthesia using an inhalation technique is appropriate in young children who may become distressed by repeated attempts at venous cannulation. Halothane is used commonly for this purpose, with induction usually being rapid and smooth [1]. However, this agent is associated with myocardial depression and arrhythmias [1, 2]. Isoflurane is metabolized to a lesser extent and tends to maintain cardiac output and rhythm [3, 4]. Two recently published studies [5, 6] have shown that isoflurane is associated with a greater incidence of hypoxia during inhalation induction of unpremedicated children compared with halothane. We wished to determine if premedication alters the incidence of respiratory complications and hypoxia during inhalation induction of anaesthesia with either of these agents. PATIENTS AND METHODS
We studied 100 healthy children weighing less than 20 kg, aged between 1 and 6 yr, who had not
been exposed to halothane within the previous 6 months. Institutional Ethics Committee approval was given for the study and informed parental consent was obtained in each case. Children were randomly allocated to one of four groups. Group NH (w = 24) received no premedication and halothane was used for induction. Group NI (M = 25) received no premedication and isoflurane. Groups TH (w = 27) and TI (n = 24) were given 40 % thiopentone suspension 30 mg kg"1 per rectum 30 min before induction with halothane or isoflurane, respectively. Premedication was administered in a paediatric surgical ward, the buttocks were taped together, and the child was transferred immediately to the adjacent theatre suite to be observed continuously by an experienced member of the nursing staff. In each patient the anaesthetic was administered by the same anaesthetist (D.W.) who had experience of use of both agents for inhalation induction in children for some years. Recordings were made by an independent observer (S.R.) who was blinded to the anaesthetic used. Before induction, each patient's sex, age, weight and demeanour were noted. Preoperative arterial oxygen saturation (5aOz) was recorded for 1 min after steady readings were obtained using a Critikon Oxyshuttle pulse oximeter probe attached to the hallux. The anaesthetist was unaware of the oximeter display and audio signals, but was informed if Sa0> decreased to less than 80 %. STEPHEN RAFTERY*, M.B., F.F.A.R.C.S.I.; DECLAN WARDE, M.B.,
F.F.A.R.C.S.I.; Department of Anaesthesia, The Children's Hospital, Temple Street, Dublin 1, Ireland. Accepted for Publication: July 3, 1989. * Present address: Department of Anaesthesia, Bristol Royal Infirmary, Bristol BS2 8HW. Correspondence to D. W.
Downloaded from http://bja.oxfordjournals.org/ at East Carolina University on July 9, 2015
SUMMARY
BRITISH JOURNAL OF ANAESTHESIA
168
TABLE I. Patient characteristics : age, weight (mean (SEM)) and sex distribution. No significant differences between groups Group NH = No premed./Halothane (n = 24) NI = No premed./Isoflurane (n = 25) TH = Thiopentone/Halothane (n = 27) TI = Thiopentone/Isoflurane (n = 24)
Age (months)
Weight (kg)
M/F
Sex
35.6 (14.8) 39.6 (15.0) 36.7(17.1) 34.5(13.8)
14.4 (3.5) 15.5 (2.3) 13.7(3.0) 14.1(2.4)
15/9 20/5 20/7 14/10
TABLE II. Preoperative demeanour and SaOl (median (range)). All differences between groups significant (P < 0.005)
Groups Unpremedicated (n = 49) Premedicated (n = 51)
Drowsy
Co-operative
Crying
Sa o (%)
0 47
27 0
22 4
99 (97-100) 97 (94-100)
Anaesthesia was induced with 60% nitrous TABLE III. Number of patients attaining various lowest oxide and the anaesthetic in oxygen. An Ayre's arterial oxygen saturations during induction. Figures in T-piece with Jackson-Rees modification was used parentheses represent the number of patients in each group (in with a fresh gas flow sufficient to prevent whom minimum saturation was within the relevant range) with rebreathing. The initial inspired concentration of airway complications. * Median Sa 0; significantly different from group NH (P < 0.05) the vapour was 0.5%, and this was increased by 0.5% every 10 breaths up to a maximum of 4%. Sa o , (%) Initially, the anaesthetic mixture was administered with the aid of a cupped hand over the Group 71 91-100 81-90 71-80 child's mouth and nose; when the eyelash reflex = 24) 20(5) had disappeared, an anaesthetic face-mask of 2(2) 15(5) 6(6) (n == 25)* 2(1) appropriate size was applied. Induction was NI 26(3) TH(« == 27) 1(1) judged to be complete when the child was 21(4) 2(2) :24) KD unconscious and breathing regularly, with eyes fixed and central, and pupils constricted. 5aOj, heart rate, inspired anaesthetic concenRESULTS tration and stage of anaesthesia were recorded every 15 s. Any events of bradycardia, struggling, The four groups were similar in age, weight and breath-holding, coughing or laryngospasm were sex distribution (table I). recorded, together with the lowest associated The premedicated children were almost all 5aOj. Time taken to induce anaesthesia was asleep or drowsy on arrival in the induction room, noted. while those unpremedicated were all either calm Parametric data (age, weight) were tested for and co-operative or crying (P < 0.005). Prestatistical significance by analysis of variance; if a medicated children had a lower SaOs than difference in the means was found, further unpremedicated (P < 0.005) (table II). Group NI analysis was carried out with Student's unpaired t children displayed lower minimum oxygen test. The Kruskal-Wallis and Wilcoxon Rank saturation than those in any of the other groups Sum tests were used for non-parametric data (P < 0.005). There was no significant difference (5aOj, induction time). The chi-square test between the other three groups with regard to with Yates' correction and Fisher's exact test were minimum SaOj (table III). used for nominal data (sex distribution, incidence Laryngospasm occurred in nine patients, all in of complications). P < 0.05 was taken as sig- group NI (P < 0.005), and in seven of these SaO! nificant. decreased to less than 91 %. Isoflurane induction
Downloaded from http://bja.oxfordjournals.org/ at East Carolina University on July 9, 2015
Demeanour
OXYGEN SATURATION AND ISOFLURANE
169
TABLE IV. Incidence (n) of complications in those children 97% or greater, 10 of the premedicated subjects whose SaOl decreased to less than 91 %, and associated median had an SaOi less than 97 %. It must be concluded, trough SaOt (in parentheses), f P < 0.05 for n, compared with therefore, that use of rectal thiopentone requires group NI. * P < 0.05 for SaOj compared with pooled groups experienced supervision and immediate availNH and TH
ability of resuscitation equipment. The major finding of our study was that premedication with rectal thiopentone reduced Event n SaOt n SaOt n SaOl n the incidence of hypoxic episodes in children in whom anaesthesia was induced with isoflurane. None 3 (86) Laryngospasm 7 (63) SaOi decreased during airway complications such Breathholding 1 (56) as laryngospasm or coughing, but in three patients Coughing 1 (89) 1 (86) 2 (64) (in group NH) hypoxia occurred in the absence of Struggling 1 (88) 2 (80) such complications. There was no significant * t t * difference in SaOi during induction between the premedicated isoflurane group and both halothane groups. The reduction in the number of TABLE V. Time taken to induce anaesthesia (median (range)).hypoxic episodes in group TI was related possibly * Median time different from group NH (P < 0.005) to the reduction in frequency of airway complications (table III). Induction time (min) Group We conclude that the frequency of hypoxia associated with inhalation induction of anaesthesia 7.25 (4.5-12) NH with isoflurane in children may be reduced by 10.25 (6.25-18) NI* premedication with rectal thiopentone, at the cost 5.5 (3.5-7.75) TH 6.75 (4.25-14.5) TI of borderline hypoxia before induction. If isoflurane is to be used for inhalation induction of anaesthesia in young children, we recommend that consideration should be given to the use of was associated with more frequent and severe sedative premedication in order to reduce the episodes of hypoxia, with concomitant laryngo- incidence of hypoxia seen with this agent. spasm, coughing or struggling. When premedication was used, these episodes were less REFERENCES frequent, but SaOz decreased to similar values 1. Pandit UA, Steude GM, Leache AB. Induction and (table IV). recovery characteristics of isoflurane and halothane anTime taken to induce anaesthesia was longer in aesthesia for short outpatient operations in children. the unpremedicated isoflurane group than the Anaesthesia 1985; 40; 1226-1230. 2. Kenna JG, Neuberger J, Mieli-Vergani G, Mowat AP, other groups (table V) (P < 0.005). NH
NI
TH
TI
Our work confirms previous findings [5, 6] demonstrating a high incidence of hypoxia during inhalation induction of anaesthesia in unpremedicated children with isoflurane, even when a slow induction technique was used by an experienced paediatric anaesthetist. The premedication regimen was effective (table II), but we were concerned to find that many of the premedicated children presented in the induction room with borderline hypoxia. While all unpremedicated children had an initial Sa o of
4.
5.
6.
Downloaded from http://bja.oxfordjournals.org/ at East Carolina University on July 9, 2015
3. DISCUSSION
Williams R. Halothane hepatitis in children. British Medical Journal 1987; 294: 1209-1210. 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. Wren WS, McShane AJ, McCarthy JG, Lamont BJ, Casey WF, Hannon VM. Isoflurane in paediatric anaesthesia. Induction and recovery from anaesthesia. Anaesthesia 1985; 40: 315-323. Phillips AJ, Brimacombe JR, Simpson DL. Anaesthetic induction with isoflurane or halothane. Oxygen saturation during induction with isoflurane or halothane in unpremedicated children. Anaesthesia 1988; 43: 927-929. Sampaio MM, Crean PM, Keilty SR, Black GW. Changes in oxygen saturation during inhalation induction of anaesthesia in children. British Journal of Anaesthesia 1989; 62: 199-201.
