Anaesthesia, 1990, Volume 45, pages 924-927
The laryngeal mask airway in paediatric anaesthesia
D. F. JOHNSTON, S. R. WRIGLEY, P. J . ROBB
AND
H. E. JONES
Summary Forty-eight children, aged between 2 and 10 years, admitted as day cases f o r otological surgery were allocated at random into two groups. Thejirst group was anaesthetised using a standard,facemask, and the second with a laryngeal mask airwuy. The laryngeal airway produced a satisfactory airway in all children, and was inserted on theJirst attempt in 67% qf patients. Hypoxia was signijicantly less ,frequent in the laryngeal airway group ( p < 0.05). and there were sign{ficantly ,fewer intrrruptions to surgery than in the facemask group ( p < 0.001). Patient safety, operating and anaesthetic conditions were all considered superior in the laryngeal airway group.
Key words Equipment; laryngeal mask airway. Surgery; paediatric, otological.
The laryngeal mask airway was introduced recently into anaesthetic practice. It provides an alternative to the facemask or tracheal tube for airway maintenance during general anaesthesia with spontaneous breathing. The Brain laryngeal airway" comprises an inflatable mould that rests above the larynx to provide a seal without the need for tracheal intubation. It was shown to be easy to introduce in adults by anaesthetists with no previous experience of its use, and provides a clear airway with the added advantage of freeing the anaesthetists' hands for other d ~ t i e s . ~ It was shown in children, that tracheal intubation can be associated with postoperative discomfort and subtle changes in laryngeal function.5 Our recent work shows there is less risk of laryngeal injury and oedema after use of the laryngeal airway compared with a tracheal tube for airway maintenance.h The majority of paediatric day-case otological procedures in our hospital are short microsurgical operations. Tracheal intubation is believed to be relatively contraindicated in this group of children because of the possible risks of laryngeal oedema and trauma. However, a facemask may necessitate interrupting the procedure from time to time, because airway maintenance may be difficult as a result of the proximity of the surgical field to the airway. These may lead to the occurrence of airway obstruction with a subsequent decrease in depth of anaesthesia, hypoxia, and patient movement. The latter is poten-
tially hazardous in microsurgical otological procedures, no matter how minor. The laryngeal mask airway appears to be a suitable alternative method for the maintenance of an airway during this type of day-case otological surgery, and one which avoids some of the risks inherent with using either a facemask o r tracheal tube, with the added advantage of a stationary microsurgical field.
Method The study was approved by the Hospital Ethics Committee and informed verbal consent was obtained from the parent or adult accompanying the child. Forty-eight children, between the ages of 2 and 10 years, of ASA 1 or 2, who presented for day-case otological surgery, were entered into the study. The children were assessed in the usual way before surgery and the normal exclusion criteria for day-case surgery applied. The type of surgery was limited to: examination of ears under anaesthesia; myringotomies with o r without the insertion of grommets or Goodes tubes. These were considered to be comparable procedures. In all children, both ears were examined. All children had EMLA cream (Astra) applied to the
D.F. Johnston, FRCS, S.R. Wrigley, FCAnaes, Registrars, P.J. Robb, FRCS, H.E. Jones, FCAnaes, Senior Registrars, Departments of Otolaryngology and Anaesthetics, Guy's Hospital, St Thomas Street, London Bridge, London SE I 9RT. Accepted I April 1990.
+
0003-2409/90/ 1 10924 04 $03.00/0
@ 1990 The Association of Anaesthetists of G t Britain and Ireland
924
925
The laryngeal mask airway in children dorsum of either hand at least one hour before operation, but no other premedication was given. Indirect arterial blood pressure, electrocardiogram, and oxygen saturation were monitored in all children. Data were recorded at 2-minute intervals, starting before induction of anaesthesia. Anaesthesia was induced in theatre, after establishment of intravenous access, with sodium thiopentone (4-6 mg/kg) in the presence of the parents and ward nurse. Increments of sodium thiopentone were given as necessary. Anaesthesia was maintained with isoflurane 14Y0 in oxygen (4 litres/minute) and nitrous oxide (6 litres/minute). Vaporizer settings were recorded at 2-minute intervals with the other measurements. An Ayre’s T-piece with reservoir bag was used for children of up to 20 kg body weight, and a Bain’s system for those over 20 kg. Intramuscular codeine phosphate ( 1 mg/kg) was administered to all children during operation. Once the depth of anaesthesia was considered satisfactory for either surgery to proceed with a facemask, or for the laryngeal airway to be inserted, the children were allocated to one of the two groups at random. In the first group of children (FM) anaesthesia was maintained with the facemask, and in the second group (BLA) a laryngeal airway of the appropriate size was inserted. The ease of insertion, and number of attempts required were recorded. The isoflurane was switched off when surgery was completed and 100% oxygen administered. In the BLA group the laryngeal airway was removed by the anaesthetist in theatre. Both groups then received oxygen via an M C mask while in transit to the recovery room and until awake. All surgical procedures were performed and anaesthetics given by the authors. The data were recorded by an independent trained observer. The following times were recorded: induction of anaesthesia: randomisation; start of surgery; end of surgery; transfer to recovery; and wake up time. Patient comfort was assessed where possible, before and after surgery, by asking the child whether they had a sore throat. The throat was also examined for pharyngeal oedema, erythema, or bruising by one of the surgical investigators after surgery. The anaesthetic and surgical conditions were assessed using a scoring system related to anaesthetic events, and surgical field as perceived by the surgeon. These are summarised in Table 1. The study could not be blinded in technique to the surgeon. The data collected were analysed using Chi-squared and Student’s ttest where appropriate.
Table 1. Criteria used to score anaesthetic and surgical conditions.
Results The two groups were comparable for age, weight, sex, and ethnic origin (Table 2). In the F M group 21 patients were ASA 1 and three ASA 2, two of whom suffered from Down’s syndrome, with no serious cardiac anomalies o r obvious airway problems. The third child suffered from asthma that required treatment with inhaled bronchodilators. In the BLA group all were ASA I . The mean heart rate, arterial blood pressure (systolic and diastolic), oxygen saturation, total dose of thiopentone, and percentage of isoflurane delivered are shown in Table 3. The mean length of surgical time in the BLA group (5.77 minutes) was sigiiificantly shorter (p < 0.05) than in the F M group (7.75 minutes), Table 4.Tables 5 and 6 show the anaesthetic and surgical conditions with the number of children in each group. It can be seen that in the BLA group there is only one child in whom the surgical field was less than ideal. This was due to the child coughing. In the F M group, it was often necessary to interrupt surgery in order to rearrange the airway, o r for a tremor to be Table 2. Demographic data of children in both groups. Values expressed as mean (SD) range or total numbers.
Laryngeal airway
Facemask
6.74 (2.67) 2.75-10.67 22.81 (8.04) 13-45 12 12 24 0 22 2 0
6.69 (1.98) 2.75-10.75 23.20 (7.70) 14-37 II 13 21 3
Age; years Weight; kg Female
Male ASA 1 ASA 2 Caucasian Negroid Mixed
18
4 2
Table 3. Measured physiological variables and drugs given. Values expressed as mean (SD).
Laryngeal Heart rate; beats/minute Systolic blood pressure; mmHg Diastolic blood pressure; mmHg Percentage oxygen saturation Percentage isoflurane used Total dose thiopentone; mg/kg
airway
Facemask
120.6 (14.6)
116.7 (15.7)
114.6 (10.3)
112.2 (12.9)
61.6 (8.8) 97.3 (1.9) 3.0 (0.5)
60.0 (10.0) 96.5 (1.7) 2.8 (0.5)
6.8 (1.4)
7.2 (2.3)
Anaesthetic score A B C D
Uneventful procedure Oxygen saturation less than or equal to 94% Patient moving ( + B) Coughing or laryngospasm ( & B or C)
Table 4. Measured and derived times mean (SD).
Laryngeal airway
Facemask
Surgical score A Completely ideal operating field B Minor movements of surgical field C Rearrangement of airway not disrupting surgery D Rearrangement of airway: surgery stopped < 30 seconds E Rearrangement of airway: surgery stopped > 30 seconds
Randomisation; minutes Start of surgery; minutes End of surgery; minutes Time awake; minutes Duration of surgery; minutes *p < 0.05 (Student’s [-test)
3.82 5.82 11.59 31.21 5.77
(1.52) (2.20) (2.20) (7.52) ( I .75)
3.84 4.84 12.59 33.24 7.75
(1.54) (1.89) (3.78) (9.59) (4.?8)*
926
D.F. Johnston et al.
Table 5. Number of children in each category for anaesthetic
Table 7. Laryngeal mask size with number of children and their
age and weight ranges.
conditions (total number). Anaesthetic score
Laryngeal mask
Facemask
A B C
19*
II 8 3 2
3 2
D *p < 0.05 (Chi-squared) A: B, C
and D.
Table 6. Number of children in each category for surgical
conditions (total number). Surgical score
Laryngeal mask
Facemask
A
23*
B C D E
1
12 7 3 2
*p < 0.001 (Chi-squared) A: B, C, D and E.
transmitted to the surgical field from the anaesthetist holding the airway. The number of children who developed changes in their oxygen saturation was significant. An oxygen saturation of less than, or equal to, 94% was considered hypoxic for the purposes of this study. Twenty (83%) in the BLA group had no episodes of hypoxia, two (8.5%) experienced a brief episode during induction of anaesthesia and a further two (S.5Y0)had two episodes; one occurred during induction and one after randomisation in both children. One of the last two children had a baseline oxygen saturation that started at 95% and decreased to 94% at induction and for a short time after the start of surgery. The second child, one in whom surgical conditions were less than ideal, had a persistent cough before surgery, and coughed and moved during the anaesthetic and surgery with a decrease in oxygen saturation. In the F M group, 1 1 (46%) children had no episodes of hypoxia, six (25%) had one episode, and seven (29%) had two episodes. In all, there were 20 episodes of hypoxia; six occurred before randomisation and 14 afterwards. There were 10 children in whom the oxygen
‘T 97
**
05 Facemask
Laryngeal mask
Fig. 1. The lowest oxygen saturation recorded in each child after
randomisation.
Size 1 2 3
Number
Age (years)
Weight (kg)
3
2.75-3.67 4.75-10.17 10.08-10.67
13.0- 15.0 14.5-38.0 29.5-45.0
19
2
saturation decreased to 94% o r less after randomisation on one or more occasion. Figure 1 shows the lowest oxygen saturation recorded in each child after randomisation. There is a significant difference (p < 0.02:Chi-squared) between the groups for the number of hypoxic episodes after randomisation. Four children in the F M group required a Guedel airway to assist with airway maintenance. The laryngeal mask could be inserted to achieve a clear airway in all the children in the BLA group. In one child, the airway became less than ideal during surgery because of coughing, as discussed above. In 16 (67%) children the laryngeal mask was inserted at the first attempt, after two attempts in six (25%), and two (8%) required three attempts. The average number of attempts at insertion was 1.42. Three children required a size 1 laryngeal airway, 19 size 2 and two size 3. Table 7 summarises this together with the age and weight ranges of the children for each size airway. Two in the F M group and four in the BLA group, of those children who could understand, admitted to a sore throat after the operation. None of the children in the F M group had signs of pharyngeal erythema after operation, whilst three of those in the BLA group did so. Two of these children complained of a sore throat and one did not.
Discussion This study demonstrates that the Brain laryngeal airway can be used safely and effectively in paediatric anaesthesia. The airway was successfully introduced at the first attempt in 67% of the children in the BLA group. The possible reasons for failure in the other children at the first attempt include lack of lubrication, inadequate depth of anaesthesia, o r inappropriate choice of laryngeal mask size. I t was suggested that the laryngeal airway is easier to insert using propofol as an induction agent;’ the first time success rate may have exceeded the 67% of our experience with this agent. However, the drug is not yet licensed for paediatric practice. The majority of ‘first time failures’ occurred early in the study, and could be an expected element of a learning curve. Improvement was observed as the study progressed. Nevertheless, in all children in the BLA group, a clear airway was eventually obtained. Overall, time between induction of anaesthesia and end of surgery was shorter in the BLA group. This may have been because no anaesthetic events interrupted surgery. The laryngeal airway appears to have both surgical and anaesthetic advantages in this type of paediatric surgery. The laryngeal mask airway produces a more secure and safe airway than the facemask, as shown by the different incidence of episodes of desaturation in the BLA group (2) compared with the F M group (14) after randomisation. This may be partly explained by the close proximity of the surgical field to the airway that makes it difficult to main-
The laryngeal mask airway in children tain the airway with a facemask. The surgical score was probably a direct result of a more secure airway that led to less interruption, and a motionless surgical field with the laryngeal airway. The duration of the operating time was between 6 and 8 minutes in this study, with experienced surgeons; during earlier training, surgery can take u p to 25-30 minutes. It would seem, in these circumstances, that the laryngeal mask would be ideal and would give a secure airway with a still surgical field to aid teaching and ensure patient safety. The aim of this study was to assess the use of the laryngeal mask airway in paediatric otological surgery. Two of the patients presenting had Down’s syndrome, in whom pre-operative assessment did not indicate a potential airway problem; both were in the FM group. One had an uneventful anaesthetic and the other two episodes of low oxygen saturation. Children with congenital abnormalities often have potentially difficult airways and associated middle-ear problems, e.g. Pierre-Robin and TreacherCollins syndromes. The role of the laryngeal mask in these situations still needs to be evaluated although there are isolated case reports’ of the successful use of the laryngeal mask in children with some anomalies. The Brain laryngeal airway can be safely and effectively used in paediatric patients and appears to have advantages in comparison with the facemask for otological surgery.
927
Acknowledgments We are grateful to the nursing staff and operating department assistants in the Day Case Theatre at Guy’s Hospital for their help and cooperation with this study. We also thank D r J.E. Fairfield and Professor R.M. Jones for their assistance in the preparation of this paper.
References I. BRAINAIJ, MCCHEE T D , MCATEEREJ, THOMAS A, ABU-SAAII MAW, BUSHMAN JA. The laryngeal mask airway. Development and preliminary trials of a new type of airway. Anaesthesia 1985; 4 0 356-61. 2. BRAINAIJ. The laryngeal mask-a new concept in airway management. British Journal of Anaesthesia 1983; 5 5 801-5. 3. BRAINAIJ. Further developments of the laryngeal mask. Anaesthesia 1989; 44: 530. 4. BRODRICK PM, WEBSTERNR, NUNNJF. The laryngeal mask airway. Anaesthesia 1989; 44:23841. 5. GLEESONMJ, FOURCIN AJ. Clinical analysis of laryngeal trauma secondary to intubation. Journal of the Royal S o c i r ~ y of Medicine 1983; 7 6 928-32. 6. HARRIS T M , JOHNSTON DF, COLLINS SRC, HEATHML. A new general anaesthetic technique for use in singers: The Brain laryngeal mask airway versus endotracheal intubation. Journal of Voice 1990; 4 81-5. 7. BURRIDGE ME. Laryngeal mask anaesthesia for repair of cleft palate. Anaesthesia 1989; 44: 656-1.
The laryngeal mask airway in paediatric anaesthesia
D. F. JOHNSTON, S. R. WRIGLEY, P. J . ROBB
AND
H. E. JONES
Summary Forty-eight children, aged between 2 and 10 years, admitted as day cases f o r otological surgery were allocated at random into two groups. Thejirst group was anaesthetised using a standard,facemask, and the second with a laryngeal mask airwuy. The laryngeal airway produced a satisfactory airway in all children, and was inserted on theJirst attempt in 67% qf patients. Hypoxia was signijicantly less ,frequent in the laryngeal airway group ( p < 0.05). and there were sign{ficantly ,fewer intrrruptions to surgery than in the facemask group ( p < 0.001). Patient safety, operating and anaesthetic conditions were all considered superior in the laryngeal airway group.
Key words Equipment; laryngeal mask airway. Surgery; paediatric, otological.
The laryngeal mask airway was introduced recently into anaesthetic practice. It provides an alternative to the facemask or tracheal tube for airway maintenance during general anaesthesia with spontaneous breathing. The Brain laryngeal airway" comprises an inflatable mould that rests above the larynx to provide a seal without the need for tracheal intubation. It was shown to be easy to introduce in adults by anaesthetists with no previous experience of its use, and provides a clear airway with the added advantage of freeing the anaesthetists' hands for other d ~ t i e s . ~ It was shown in children, that tracheal intubation can be associated with postoperative discomfort and subtle changes in laryngeal function.5 Our recent work shows there is less risk of laryngeal injury and oedema after use of the laryngeal airway compared with a tracheal tube for airway maintenance.h The majority of paediatric day-case otological procedures in our hospital are short microsurgical operations. Tracheal intubation is believed to be relatively contraindicated in this group of children because of the possible risks of laryngeal oedema and trauma. However, a facemask may necessitate interrupting the procedure from time to time, because airway maintenance may be difficult as a result of the proximity of the surgical field to the airway. These may lead to the occurrence of airway obstruction with a subsequent decrease in depth of anaesthesia, hypoxia, and patient movement. The latter is poten-
tially hazardous in microsurgical otological procedures, no matter how minor. The laryngeal mask airway appears to be a suitable alternative method for the maintenance of an airway during this type of day-case otological surgery, and one which avoids some of the risks inherent with using either a facemask o r tracheal tube, with the added advantage of a stationary microsurgical field.
Method The study was approved by the Hospital Ethics Committee and informed verbal consent was obtained from the parent or adult accompanying the child. Forty-eight children, between the ages of 2 and 10 years, of ASA 1 or 2, who presented for day-case otological surgery, were entered into the study. The children were assessed in the usual way before surgery and the normal exclusion criteria for day-case surgery applied. The type of surgery was limited to: examination of ears under anaesthesia; myringotomies with o r without the insertion of grommets or Goodes tubes. These were considered to be comparable procedures. In all children, both ears were examined. All children had EMLA cream (Astra) applied to the
D.F. Johnston, FRCS, S.R. Wrigley, FCAnaes, Registrars, P.J. Robb, FRCS, H.E. Jones, FCAnaes, Senior Registrars, Departments of Otolaryngology and Anaesthetics, Guy's Hospital, St Thomas Street, London Bridge, London SE I 9RT. Accepted I April 1990.
+
0003-2409/90/ 1 10924 04 $03.00/0
@ 1990 The Association of Anaesthetists of G t Britain and Ireland
924
925
The laryngeal mask airway in children dorsum of either hand at least one hour before operation, but no other premedication was given. Indirect arterial blood pressure, electrocardiogram, and oxygen saturation were monitored in all children. Data were recorded at 2-minute intervals, starting before induction of anaesthesia. Anaesthesia was induced in theatre, after establishment of intravenous access, with sodium thiopentone (4-6 mg/kg) in the presence of the parents and ward nurse. Increments of sodium thiopentone were given as necessary. Anaesthesia was maintained with isoflurane 14Y0 in oxygen (4 litres/minute) and nitrous oxide (6 litres/minute). Vaporizer settings were recorded at 2-minute intervals with the other measurements. An Ayre’s T-piece with reservoir bag was used for children of up to 20 kg body weight, and a Bain’s system for those over 20 kg. Intramuscular codeine phosphate ( 1 mg/kg) was administered to all children during operation. Once the depth of anaesthesia was considered satisfactory for either surgery to proceed with a facemask, or for the laryngeal airway to be inserted, the children were allocated to one of the two groups at random. In the first group of children (FM) anaesthesia was maintained with the facemask, and in the second group (BLA) a laryngeal airway of the appropriate size was inserted. The ease of insertion, and number of attempts required were recorded. The isoflurane was switched off when surgery was completed and 100% oxygen administered. In the BLA group the laryngeal airway was removed by the anaesthetist in theatre. Both groups then received oxygen via an M C mask while in transit to the recovery room and until awake. All surgical procedures were performed and anaesthetics given by the authors. The data were recorded by an independent trained observer. The following times were recorded: induction of anaesthesia: randomisation; start of surgery; end of surgery; transfer to recovery; and wake up time. Patient comfort was assessed where possible, before and after surgery, by asking the child whether they had a sore throat. The throat was also examined for pharyngeal oedema, erythema, or bruising by one of the surgical investigators after surgery. The anaesthetic and surgical conditions were assessed using a scoring system related to anaesthetic events, and surgical field as perceived by the surgeon. These are summarised in Table 1. The study could not be blinded in technique to the surgeon. The data collected were analysed using Chi-squared and Student’s ttest where appropriate.
Table 1. Criteria used to score anaesthetic and surgical conditions.
Results The two groups were comparable for age, weight, sex, and ethnic origin (Table 2). In the F M group 21 patients were ASA 1 and three ASA 2, two of whom suffered from Down’s syndrome, with no serious cardiac anomalies o r obvious airway problems. The third child suffered from asthma that required treatment with inhaled bronchodilators. In the BLA group all were ASA I . The mean heart rate, arterial blood pressure (systolic and diastolic), oxygen saturation, total dose of thiopentone, and percentage of isoflurane delivered are shown in Table 3. The mean length of surgical time in the BLA group (5.77 minutes) was sigiiificantly shorter (p < 0.05) than in the F M group (7.75 minutes), Table 4.Tables 5 and 6 show the anaesthetic and surgical conditions with the number of children in each group. It can be seen that in the BLA group there is only one child in whom the surgical field was less than ideal. This was due to the child coughing. In the F M group, it was often necessary to interrupt surgery in order to rearrange the airway, o r for a tremor to be Table 2. Demographic data of children in both groups. Values expressed as mean (SD) range or total numbers.
Laryngeal airway
Facemask
6.74 (2.67) 2.75-10.67 22.81 (8.04) 13-45 12 12 24 0 22 2 0
6.69 (1.98) 2.75-10.75 23.20 (7.70) 14-37 II 13 21 3
Age; years Weight; kg Female
Male ASA 1 ASA 2 Caucasian Negroid Mixed
18
4 2
Table 3. Measured physiological variables and drugs given. Values expressed as mean (SD).
Laryngeal Heart rate; beats/minute Systolic blood pressure; mmHg Diastolic blood pressure; mmHg Percentage oxygen saturation Percentage isoflurane used Total dose thiopentone; mg/kg
airway
Facemask
120.6 (14.6)
116.7 (15.7)
114.6 (10.3)
112.2 (12.9)
61.6 (8.8) 97.3 (1.9) 3.0 (0.5)
60.0 (10.0) 96.5 (1.7) 2.8 (0.5)
6.8 (1.4)
7.2 (2.3)
Anaesthetic score A B C D
Uneventful procedure Oxygen saturation less than or equal to 94% Patient moving ( + B) Coughing or laryngospasm ( & B or C)
Table 4. Measured and derived times mean (SD).
Laryngeal airway
Facemask
Surgical score A Completely ideal operating field B Minor movements of surgical field C Rearrangement of airway not disrupting surgery D Rearrangement of airway: surgery stopped < 30 seconds E Rearrangement of airway: surgery stopped > 30 seconds
Randomisation; minutes Start of surgery; minutes End of surgery; minutes Time awake; minutes Duration of surgery; minutes *p < 0.05 (Student’s [-test)
3.82 5.82 11.59 31.21 5.77
(1.52) (2.20) (2.20) (7.52) ( I .75)
3.84 4.84 12.59 33.24 7.75
(1.54) (1.89) (3.78) (9.59) (4.?8)*
926
D.F. Johnston et al.
Table 5. Number of children in each category for anaesthetic
Table 7. Laryngeal mask size with number of children and their
age and weight ranges.
conditions (total number). Anaesthetic score
Laryngeal mask
Facemask
A B C
19*
II 8 3 2
3 2
D *p < 0.05 (Chi-squared) A: B, C
and D.
Table 6. Number of children in each category for surgical
conditions (total number). Surgical score
Laryngeal mask
Facemask
A
23*
B C D E
1
12 7 3 2
*p < 0.001 (Chi-squared) A: B, C, D and E.
transmitted to the surgical field from the anaesthetist holding the airway. The number of children who developed changes in their oxygen saturation was significant. An oxygen saturation of less than, or equal to, 94% was considered hypoxic for the purposes of this study. Twenty (83%) in the BLA group had no episodes of hypoxia, two (8.5%) experienced a brief episode during induction of anaesthesia and a further two (S.5Y0)had two episodes; one occurred during induction and one after randomisation in both children. One of the last two children had a baseline oxygen saturation that started at 95% and decreased to 94% at induction and for a short time after the start of surgery. The second child, one in whom surgical conditions were less than ideal, had a persistent cough before surgery, and coughed and moved during the anaesthetic and surgery with a decrease in oxygen saturation. In the F M group, 1 1 (46%) children had no episodes of hypoxia, six (25%) had one episode, and seven (29%) had two episodes. In all, there were 20 episodes of hypoxia; six occurred before randomisation and 14 afterwards. There were 10 children in whom the oxygen
‘T 97
**
05 Facemask
Laryngeal mask
Fig. 1. The lowest oxygen saturation recorded in each child after
randomisation.
Size 1 2 3
Number
Age (years)
Weight (kg)
3
2.75-3.67 4.75-10.17 10.08-10.67
13.0- 15.0 14.5-38.0 29.5-45.0
19
2
saturation decreased to 94% o r less after randomisation on one or more occasion. Figure 1 shows the lowest oxygen saturation recorded in each child after randomisation. There is a significant difference (p < 0.02:Chi-squared) between the groups for the number of hypoxic episodes after randomisation. Four children in the F M group required a Guedel airway to assist with airway maintenance. The laryngeal mask could be inserted to achieve a clear airway in all the children in the BLA group. In one child, the airway became less than ideal during surgery because of coughing, as discussed above. In 16 (67%) children the laryngeal mask was inserted at the first attempt, after two attempts in six (25%), and two (8%) required three attempts. The average number of attempts at insertion was 1.42. Three children required a size 1 laryngeal airway, 19 size 2 and two size 3. Table 7 summarises this together with the age and weight ranges of the children for each size airway. Two in the F M group and four in the BLA group, of those children who could understand, admitted to a sore throat after the operation. None of the children in the F M group had signs of pharyngeal erythema after operation, whilst three of those in the BLA group did so. Two of these children complained of a sore throat and one did not.
Discussion This study demonstrates that the Brain laryngeal airway can be used safely and effectively in paediatric anaesthesia. The airway was successfully introduced at the first attempt in 67% of the children in the BLA group. The possible reasons for failure in the other children at the first attempt include lack of lubrication, inadequate depth of anaesthesia, o r inappropriate choice of laryngeal mask size. I t was suggested that the laryngeal airway is easier to insert using propofol as an induction agent;’ the first time success rate may have exceeded the 67% of our experience with this agent. However, the drug is not yet licensed for paediatric practice. The majority of ‘first time failures’ occurred early in the study, and could be an expected element of a learning curve. Improvement was observed as the study progressed. Nevertheless, in all children in the BLA group, a clear airway was eventually obtained. Overall, time between induction of anaesthesia and end of surgery was shorter in the BLA group. This may have been because no anaesthetic events interrupted surgery. The laryngeal airway appears to have both surgical and anaesthetic advantages in this type of paediatric surgery. The laryngeal mask airway produces a more secure and safe airway than the facemask, as shown by the different incidence of episodes of desaturation in the BLA group (2) compared with the F M group (14) after randomisation. This may be partly explained by the close proximity of the surgical field to the airway that makes it difficult to main-
The laryngeal mask airway in children tain the airway with a facemask. The surgical score was probably a direct result of a more secure airway that led to less interruption, and a motionless surgical field with the laryngeal airway. The duration of the operating time was between 6 and 8 minutes in this study, with experienced surgeons; during earlier training, surgery can take u p to 25-30 minutes. It would seem, in these circumstances, that the laryngeal mask would be ideal and would give a secure airway with a still surgical field to aid teaching and ensure patient safety. The aim of this study was to assess the use of the laryngeal mask airway in paediatric otological surgery. Two of the patients presenting had Down’s syndrome, in whom pre-operative assessment did not indicate a potential airway problem; both were in the FM group. One had an uneventful anaesthetic and the other two episodes of low oxygen saturation. Children with congenital abnormalities often have potentially difficult airways and associated middle-ear problems, e.g. Pierre-Robin and TreacherCollins syndromes. The role of the laryngeal mask in these situations still needs to be evaluated although there are isolated case reports’ of the successful use of the laryngeal mask in children with some anomalies. The Brain laryngeal airway can be safely and effectively used in paediatric patients and appears to have advantages in comparison with the facemask for otological surgery.
927
Acknowledgments We are grateful to the nursing staff and operating department assistants in the Day Case Theatre at Guy’s Hospital for their help and cooperation with this study. We also thank D r J.E. Fairfield and Professor R.M. Jones for their assistance in the preparation of this paper.
References I. BRAINAIJ, MCCHEE T D , MCATEEREJ, THOMAS A, ABU-SAAII MAW, BUSHMAN JA. The laryngeal mask airway. Development and preliminary trials of a new type of airway. Anaesthesia 1985; 4 0 356-61. 2. BRAINAIJ. The laryngeal mask-a new concept in airway management. British Journal of Anaesthesia 1983; 5 5 801-5. 3. BRAINAIJ. Further developments of the laryngeal mask. Anaesthesia 1989; 44: 530. 4. BRODRICK PM, WEBSTERNR, NUNNJF. The laryngeal mask airway. Anaesthesia 1989; 44:23841. 5. GLEESONMJ, FOURCIN AJ. Clinical analysis of laryngeal trauma secondary to intubation. Journal of the Royal S o c i r ~ y of Medicine 1983; 7 6 928-32. 6. HARRIS T M , JOHNSTON DF, COLLINS SRC, HEATHML. A new general anaesthetic technique for use in singers: The Brain laryngeal mask airway versus endotracheal intubation. Journal of Voice 1990; 4 81-5. 7. BURRIDGE ME. Laryngeal mask anaesthesia for repair of cleft palate. Anaesthesia 1989; 44: 656-1.
