Anaesthesia, 1990, Volume 45, pages 760-763
Forum The laryngeal mask airway in children
D. G. Mason, F F A R C S , Registrar, R. M. Bingham, FFARCS, Consultant, Department of Anaesthetics, Hospital for Sick Children, Great Ormond Street, London W C l 3JH.
Summary The laryngeal mask airway was used in 200 children during a variety of surgical procedures. Some problem with the use of the device was encountered in 47 cases ( 2 3 % ) , but in only five cases (2.5%) were the problems serious enough to warrant abandonment of its use. A clear airway was ultimately achieved in 191 children. Downfolding of the epiglottis over the laryngeal inlet was identijed in eight out of 24 patients where flexible laryngoscopy was performed, clinically all these had unobstructed airways. The mask was used in 16 children with known airway problems. It is concluded that the size 2 laryngeal mask airway can be successfully used within the weight range 6-30 kg. Key words Anaesthesia; paediatric. Equipment; laryngeal mask airway
The laryngeal mask airway (LMA) is the development of a new concept in upper airway management. Its inception was a result of the application of bio-engineering and the postmortem examination of the adult larynx.' This led to the creation of a prototype mask, which has been the subject of independent studies in spontaneously breathing adults.' ' A survey of the use of the commercially available LMA over one month in a district general hospital indicates the rapid growth in the use of the device in adult anaesthetic p r a ~ t i c eIt . ~appears to be relatively simple and safe to use across a wide range of surgical specia1ties.j It has also been advocated for use in the management of the difficult The device does not, however, provide a watertight seal around the larynx, and should not be used in patients at risk of regurgitation. There is a risk of gastric inflation during positive pressure ventilation. The LMA is now available for use in children in two sizes. They are scaled-down versions of the adult forms and no direct postmortem specimen work has been performed. The infant and young child have a relatively large tongue in relation to the mandible, the glottis lies higher and more anteriorly than in the adult, while the vocal cords are angled more forwards and downwards. The epiglottis is large and floppy, and may lie against the posterior wall of the pharynx which can cause upper airway obstruction during anaesthesia. We performed a clinical evaluation in paediatric anaesthesia in view of the above differences and since the use of the LMA in children is becoming increasingly common.
its use before the start of the study. The anaesthetic staff were free to use the device at their discretion. Premedication was given in almost all cases and consisted of an anticholinergic with or without an opioid or sedative drug. Induction of anaesthesia was with either 50% cyclopropane in oxygen or intravenous thiopentone. Anaesthesia was maintained using halothane, or occasionally isoflurane, in nitrous oxide and oxygen; the patients were allowed to breathe spontaneously through a T-piece system. Monitoring of arterial oxygen saturation, ECG and blood pressure was then started. The LMA was inserted when anaesthesia was adequate, the mask inflated with 10 ml air and connected to the T-piece system via a 15-mm Portex connector. It was then fixed in place using one inch Elastoplast. The device was left in situ after surgery until the return of laryngeal reflexes. A questionnaire was completed if the device was used with this information: age, weight and any pre-existing airway problems; grade of anaesthetist and previous experience with the mask; the operation and duration of insertion; the ease of insertion, the number of attempts and any associated problems; quality of the airway and manoeuvres necessary to achieve a perfect airway; presence of a leak on compression of the reservoir bag; the ease of removal and any associated problems. The only exclusion criteria were patients at risk of regurgitation of gastric contents. The position of the mask was verified as previously described.'-' In addition, in some cases, flexible laryngoscopy was performed through the LMA. The device was washed with soap and water on removal. and boiled for 3 minutes before re-use.
Method
The size 1 and 2 LMAs (which the manufacturers recommend for use in children who weigh < 6.5 kg and 6.5 to 25 kg respectively) were made available to all anaesthetists working in the department. Basic guidelines were given in
Results
The size 2 LMA was used in 200 children during a period of 3 months. Table 1 give the details of the demographic data and duration of insertion of the mask and shows that
Accepted 17 January 1990. 0003-2409/90/090760
+ 21 S03.00jO
@ 1990 The Association of Anaesthetists of Gt Britain and Ireland
760
76 1
Forum Table 5. Manoeuvres used to relieve airway obstruction.
Table 1. Demographic details and duration of insertion.
Median
Range
3.7 15.2 30
0.5-1 1.9 5.745.0
Number
~~
Age (years) Weight (kg)
Duration (minutes)
70
1
7.c90.0
1
Age o f children ( y e a r s )
Fig. 1. Age distribution of children.
Table 2. Problems with the use of the LMA related to previous
experience. Previous experience (Number of cases)
Number of problems
c 5 > 5 10 < 15 >15 20
18/56 (32%) 10/27 (37%) 3/18 (17%) 1/10 (10%)
15/89 (17%)
Table 3. Operative procedures.
Number % 75 (37.5) 44 (22) 21 (10.5) 18 (9.0) 13 (6.5) 13 (6.5) 11 (5.5) 5 (2.5)
General surgery Orthopaedics Plastic surgery ENT/dental Radiology Urology Ophthalmology Other
Table 4. Problems related to insertion and removal. ~
Insertion
Difficulty in negotiating posterior pharynx Coughing Laryngospasm Desaturation > 5% Breath holding Vomiting Excess saliva
Number
Removal
Number
10
Coughing
12
Biting Laryngospasm Retching Vomiting Other
11 5
5 4 3 2 1 1
4 3 2
Remove and reinsert Reposition head Add more air to mask Remove air from mask Apply CPAP Abandon
13 6 5
2 1
5
the device was used successfully at weights above and below those recommended. The age distribution of the children is shown in Figure 1. Sixteen anaesthetists participated in the study. Six were consultants who between them inserted 74 masks, four were senior registrars who inserted 28 masks and the remaining 98 masks were inserted by six registrars. The number of problems encountered related to previous experience with the device is shown in Table 2. It was used across a large range of surgical specialties (Table 3), but most frequently for general surgical and orthopaedic procedures. Some problem with the use of the device was encountered in 47 cases (23%), but in only five cases (2.5%) were the problems serious enough to warrant abandonment of its use. It was easy to insert in 185 (92.5%) cases. Problems occurred in 22 patients immediately after insertion (Table 4). Two of these patients had multiple problems and the use of the device was abandoned. The L M A was correctly inserted on the first attempt in 179 (89.5%) cases. Of the 21 remaining, two were then abandoned and of the other 19, 16 were successfully inserted o n the second attempt. None of the remaining three were successfully inserted despite further attempts. One hundred and seventy-eight children had a completely clear airway after successful insertion. A clear airway was ultimately achieved after a variety of manoeuvres (Table 5) in 191 children. Four of the remaining nine patients had partial obstruction but the use of the device was continued and five were abandoned for a number of reasons. A 5-year-old child had previous subglottic stenosis and despite three attempts at insertion, an unobstructed airway could not be achieved; subsequent tracheal intubation was performed uneventfully. Two others aged 22 months and 9 years had no known airway problems, but coughing, laryngospasm and vomiting occurred after insertion. Insufficient anaesthesia was responsible in both cases. In addition, excessive secretions from lack of premedication aggravated the situation in the second child. Complete airway obstruction occurred in the two remaining children, aged 2 and 5.5 years, despite three attempts a t insertion. A n oropharyngeal airway and facemask were subsequently employed. A leak was audible in 52% of cases on gentle manual compression of the reservoir bag. No formal attempt to quantify the degree of leak was made. No further problems were reported until the recovery period, once the device was successfully inserted and a clear airway achieved. The L M A was removed with ease in 191 children (95.5%), but problems associated with removal occurred in 26 cases (Table 4). Single problems occurred in 19, while seven had multiple problems. No child required active intervention, other than removal of the device, as a result of problems o n recovery. In 24 patients direct laryngoscopic views of the laryngeal inlet were obtained using a flexible fibreoptic bronchoscope. In 16 of these endoscopies the vocal cords could be clearly seen, while in eight downfolding of the epiglottis
762
Forum beneath fenestrations of the LMA aperture was observed (Fig. 2). Airway problems existed in 16 patients before the use of the L M A (Table 6). One case was abandoned as described above, one had partial airway obstruction and four required more than one attempt at insertion to achieve a satisfactory airway. The size 1 mask was only used on two occasions.
Discussion
Fig. 2. Photographic views as seen through the LMA of the laryngeal inlet. The vocal cords and arytenoids can be seen clearly on the left, while downfolding of the epiglottis beneath the fenestrations of the mask aperture has occurred on the right.
Table 6. Known airway problems.
Comments Partial obstruction abandoned after three attempts of insertion No problems Amyoplasia congenita Four had no problems. One had Apert’s syndrome, five cases excess secretions and required two attempts of insertion One had laryngospasm and Cleft palate, two cases required two attempts of insertion Had laryngospasm and required Tracheomalacia, post aortotwo attempts of insertion PexY Haemangioma of pharynx and No problems larynx No problems Multiple fibromatosis No problems Sleep apnoea upper airway obstruction Required two attempts of Haemangioma on lip insertion No problems Hydrocephalus and achondroplasia Partial obstruction Other
Subglottic stenosis
The various merits and limitations of the LMA in adults have been described.’ Our incidence of major problems that resulted in abandonment of its use (2.5%) is comparable with that reported by Minor problems, however, occurred more frequently in our study. Inadequate anaesthesia on insertion of the L M A may result in coughing, vomiting, and laryngospasm. Thus sufficient anaesthesia is essential and this appears to be greater than that required for insertion of a n oropharyngeal airway, but less than that for tracheal intubation. In some cases, particularly in children with tonsillar hypertrophy, insertion can prove difficult, but can be facilitated by ensuring that an antisialogue premedicant has been given, that the head is well extended, and that firm pressure of the device on the hard palate is applied in order to negotiate the posterior pharyngeal wall. Other manoeuvres can be employed to overcome this obstacle, namely by slight lateral insertion of the mask, by the use of a finger on the posterior wall of the mask acting as a guide, and by pulling the tongue forwards with a dry swab. Once inserted, accidental dislodgement can occur, especially in the younger child, where there is a substantial portion of the tube protruding from the mouth. Thus it is important to fix the L M A securely in place. Biting on the tube of the LMA during recovery can cause airway obstruction. This can be overcome by the use of a bite block such as Guedel airway which should be inserted at the same time as the L M A and also securely fixed in place. The device does not provide an absolute guarantee of a secure airway, or of laryngeal protection, since it does not provide a watertight seal and thus aspiration may occur in patients who are at risk of regurgitation of gastric contents. Similarly, many of the problems encountered on recovery appeared to be due to accumulation of secretions within the mask aperture.
Fig. 3. The size 2 laryngeal mask airway.
Forum Intermittent positive pressure ventilation via the LMA could potentially result in gastric inflation which, in children, will cause splinting of the diaphragm and compromise respiratory function. The lungs of two of the patients in the study were ventilated successfully, but further work will need to be performed to validate this technique in children. The LMA was used in several children with known difficult airways, but problems did occur. Hence great caution should be taken with these patients. It is important that alternative means to maintain an airway are available and that there is ready access to the patient’s head. We would not regard the device as the technique of choice for patients with known airway problems presenting for major head and neck surgery. We were interested to note that downfolding of the epiglottis does occur as feared in some cases. Surprisingly, this did not result in airway obstruction. Presumably this is because the area between the edges of the epiglottis and the rim of the mask aperture is sufficiently large to allow unobstructed ventilation. The LMA proved particularly suitable for the spontaneously breathing child as an alternative to the use of a mask and airway or tracheal tube. I t maintained a clear airway without the need for laryngoscopy and intubation and allowed both hands to be free. The size-2 L M A was remarkably versatile in that it could be used over a wide age range. The mask was well tolerated once in place, even at light planes of anaesthesia. Airway maintenance during recovery was facilitated. The device was removed once the patients were awake and had full return of their laryngeal reflexes. Connexion directly to a T-piece system provided an additional monitor of respiration whilst 100% oxygen was administered. As in adults, the LMA was particularly useful for minor head and neck procedures such as myringotomy and for peripheral limb, minor general and urogenital surgery in conjunction with a local anaesthetic block. We consider that the L M A provides the anaesthetist with
763
an additional aid in the management of the upper airway in children during spontaneous breathing. An adequate period of starvation is essential before its use, and an antisialogue premedicant should be given. Any method of induction is suitable for its insertion in children, but an adequate depth of anaesthesia is necessary. Secure fixation is important to prevent accidental dislodgement, and the use of an oropharyngeal airway one size smaller than for the age of the child acts as a good bite block. The size-2 L M A can be successfully used within a weight range of between 6 kg to 30 kg. Acknowledgments
The authors thank D r I.G. Johnston and all the members of the anaesthetic department at the Hospital for Sick Children, Great Ormond Street for their assistance during this study and D r J.S. Sherrard for her help in text preparation. References 1. BRAINAIJ. The laryngeal mask-a new concept in airway management. British Journal of Anaesthesia 1983; 55: 801-5. 2. BRAINAIJ, MCGHEETD, MCATEEREJ, THOMAS A, ABU-SAAD MAW, BUSHMANJA. The laryngeal mask airway. Development and preliminary trials of a new type of airway. Anaesthesia 1985; 4 0 35661. 3. BRODRICK PM, WEBSTERNR, NUNNJF. The laryngeal mask airway. A study of 100 patients during spontaneous breathing. Anaesthesia 1989; 44: 2 3 8 4 1 . 4. ALEXANDER CA, LEACHAB. The laryngeal mask-experience of its use in a district general hospital. Toduy’s Anaesthetist 1989; 4 20&5. 5. BRAINAIJ. Three cases of difficult intubation overcome by the laryngeal mask airway. Anaesthesia 1985; 40: 353-5. 6. BEVERIDGE ME. Laryngeal mask anaesthesia for repair of cleft palate. Anaesthesia 1989; 44: 656-7. 7. SMITHBL. Brain airway in anaesthesia for patients with juvenile chronic arthritis. Anaesthesia 1988; 43: 421.
Anaesthesia, 1990, Volume 45, pages 763-766 Intravenous diclofenac sodium Does its administration before operation suppress postoperative pain?
W. I. Campbell, MB, FFARCSI, Consultant, R. Kendrick, MB, FDS, FFD, Consultant Oral Surgeon, Department of Anaesthetics, The Ulster Hospital, Dundonald, Belfast BTI 6 ORH, C. Patterson, MSc, Lecturer in Medical Statistics, Queens University, Belfast.
Summary Intravenous diclofenac sodium was evaluated in a double-blind randomised trial relative to intramuscular diclofenac, intravenous jkntanyl, and intramuscular placebo in 160 patients undergoing extraction of impacted lower third molar teeth. The test drug was administered before operation in an attempt to alleviate postoperative pain. A 10-cm visual analogue scale was used to assess pain at 30 minutes and one day after surgery, if the patients stayed overnight. Patients who received intravenous diclofenac had significantly less pain than the other groups 30 minutes after operation. They also had signijicantly less pain one day after surgery than the placebo or opioid groups, but not less than the intramuscular diclofenac group. Capillary bleeding time, in comparison with placebo, was signifcantly prolonged after the use of intramuscular diclofenac. and a similar but nonsignijkant trend was observed in the intravenous diclofenac group. N o problems were encountered with excessive bleeding in any group. Key words: Analgesics; diclofenac, fentanyl. Pain; postoperative.
Accepted 23 January 1990.
Forum The laryngeal mask airway in children
D. G. Mason, F F A R C S , Registrar, R. M. Bingham, FFARCS, Consultant, Department of Anaesthetics, Hospital for Sick Children, Great Ormond Street, London W C l 3JH.
Summary The laryngeal mask airway was used in 200 children during a variety of surgical procedures. Some problem with the use of the device was encountered in 47 cases ( 2 3 % ) , but in only five cases (2.5%) were the problems serious enough to warrant abandonment of its use. A clear airway was ultimately achieved in 191 children. Downfolding of the epiglottis over the laryngeal inlet was identijed in eight out of 24 patients where flexible laryngoscopy was performed, clinically all these had unobstructed airways. The mask was used in 16 children with known airway problems. It is concluded that the size 2 laryngeal mask airway can be successfully used within the weight range 6-30 kg. Key words Anaesthesia; paediatric. Equipment; laryngeal mask airway
The laryngeal mask airway (LMA) is the development of a new concept in upper airway management. Its inception was a result of the application of bio-engineering and the postmortem examination of the adult larynx.' This led to the creation of a prototype mask, which has been the subject of independent studies in spontaneously breathing adults.' ' A survey of the use of the commercially available LMA over one month in a district general hospital indicates the rapid growth in the use of the device in adult anaesthetic p r a ~ t i c eIt . ~appears to be relatively simple and safe to use across a wide range of surgical specia1ties.j It has also been advocated for use in the management of the difficult The device does not, however, provide a watertight seal around the larynx, and should not be used in patients at risk of regurgitation. There is a risk of gastric inflation during positive pressure ventilation. The LMA is now available for use in children in two sizes. They are scaled-down versions of the adult forms and no direct postmortem specimen work has been performed. The infant and young child have a relatively large tongue in relation to the mandible, the glottis lies higher and more anteriorly than in the adult, while the vocal cords are angled more forwards and downwards. The epiglottis is large and floppy, and may lie against the posterior wall of the pharynx which can cause upper airway obstruction during anaesthesia. We performed a clinical evaluation in paediatric anaesthesia in view of the above differences and since the use of the LMA in children is becoming increasingly common.
its use before the start of the study. The anaesthetic staff were free to use the device at their discretion. Premedication was given in almost all cases and consisted of an anticholinergic with or without an opioid or sedative drug. Induction of anaesthesia was with either 50% cyclopropane in oxygen or intravenous thiopentone. Anaesthesia was maintained using halothane, or occasionally isoflurane, in nitrous oxide and oxygen; the patients were allowed to breathe spontaneously through a T-piece system. Monitoring of arterial oxygen saturation, ECG and blood pressure was then started. The LMA was inserted when anaesthesia was adequate, the mask inflated with 10 ml air and connected to the T-piece system via a 15-mm Portex connector. It was then fixed in place using one inch Elastoplast. The device was left in situ after surgery until the return of laryngeal reflexes. A questionnaire was completed if the device was used with this information: age, weight and any pre-existing airway problems; grade of anaesthetist and previous experience with the mask; the operation and duration of insertion; the ease of insertion, the number of attempts and any associated problems; quality of the airway and manoeuvres necessary to achieve a perfect airway; presence of a leak on compression of the reservoir bag; the ease of removal and any associated problems. The only exclusion criteria were patients at risk of regurgitation of gastric contents. The position of the mask was verified as previously described.'-' In addition, in some cases, flexible laryngoscopy was performed through the LMA. The device was washed with soap and water on removal. and boiled for 3 minutes before re-use.
Method
The size 1 and 2 LMAs (which the manufacturers recommend for use in children who weigh < 6.5 kg and 6.5 to 25 kg respectively) were made available to all anaesthetists working in the department. Basic guidelines were given in
Results
The size 2 LMA was used in 200 children during a period of 3 months. Table 1 give the details of the demographic data and duration of insertion of the mask and shows that
Accepted 17 January 1990. 0003-2409/90/090760
+ 21 S03.00jO
@ 1990 The Association of Anaesthetists of Gt Britain and Ireland
760
76 1
Forum Table 5. Manoeuvres used to relieve airway obstruction.
Table 1. Demographic details and duration of insertion.
Median
Range
3.7 15.2 30
0.5-1 1.9 5.745.0
Number
~~
Age (years) Weight (kg)
Duration (minutes)
70
1
7.c90.0
1
Age o f children ( y e a r s )
Fig. 1. Age distribution of children.
Table 2. Problems with the use of the LMA related to previous
experience. Previous experience (Number of cases)
Number of problems
c 5 > 5 10 < 15 >15 20
18/56 (32%) 10/27 (37%) 3/18 (17%) 1/10 (10%)
15/89 (17%)
Table 3. Operative procedures.
Number % 75 (37.5) 44 (22) 21 (10.5) 18 (9.0) 13 (6.5) 13 (6.5) 11 (5.5) 5 (2.5)
General surgery Orthopaedics Plastic surgery ENT/dental Radiology Urology Ophthalmology Other
Table 4. Problems related to insertion and removal. ~
Insertion
Difficulty in negotiating posterior pharynx Coughing Laryngospasm Desaturation > 5% Breath holding Vomiting Excess saliva
Number
Removal
Number
10
Coughing
12
Biting Laryngospasm Retching Vomiting Other
11 5
5 4 3 2 1 1
4 3 2
Remove and reinsert Reposition head Add more air to mask Remove air from mask Apply CPAP Abandon
13 6 5
2 1
5
the device was used successfully at weights above and below those recommended. The age distribution of the children is shown in Figure 1. Sixteen anaesthetists participated in the study. Six were consultants who between them inserted 74 masks, four were senior registrars who inserted 28 masks and the remaining 98 masks were inserted by six registrars. The number of problems encountered related to previous experience with the device is shown in Table 2. It was used across a large range of surgical specialties (Table 3), but most frequently for general surgical and orthopaedic procedures. Some problem with the use of the device was encountered in 47 cases (23%), but in only five cases (2.5%) were the problems serious enough to warrant abandonment of its use. It was easy to insert in 185 (92.5%) cases. Problems occurred in 22 patients immediately after insertion (Table 4). Two of these patients had multiple problems and the use of the device was abandoned. The L M A was correctly inserted on the first attempt in 179 (89.5%) cases. Of the 21 remaining, two were then abandoned and of the other 19, 16 were successfully inserted o n the second attempt. None of the remaining three were successfully inserted despite further attempts. One hundred and seventy-eight children had a completely clear airway after successful insertion. A clear airway was ultimately achieved after a variety of manoeuvres (Table 5) in 191 children. Four of the remaining nine patients had partial obstruction but the use of the device was continued and five were abandoned for a number of reasons. A 5-year-old child had previous subglottic stenosis and despite three attempts at insertion, an unobstructed airway could not be achieved; subsequent tracheal intubation was performed uneventfully. Two others aged 22 months and 9 years had no known airway problems, but coughing, laryngospasm and vomiting occurred after insertion. Insufficient anaesthesia was responsible in both cases. In addition, excessive secretions from lack of premedication aggravated the situation in the second child. Complete airway obstruction occurred in the two remaining children, aged 2 and 5.5 years, despite three attempts a t insertion. A n oropharyngeal airway and facemask were subsequently employed. A leak was audible in 52% of cases on gentle manual compression of the reservoir bag. No formal attempt to quantify the degree of leak was made. No further problems were reported until the recovery period, once the device was successfully inserted and a clear airway achieved. The L M A was removed with ease in 191 children (95.5%), but problems associated with removal occurred in 26 cases (Table 4). Single problems occurred in 19, while seven had multiple problems. No child required active intervention, other than removal of the device, as a result of problems o n recovery. In 24 patients direct laryngoscopic views of the laryngeal inlet were obtained using a flexible fibreoptic bronchoscope. In 16 of these endoscopies the vocal cords could be clearly seen, while in eight downfolding of the epiglottis
762
Forum beneath fenestrations of the LMA aperture was observed (Fig. 2). Airway problems existed in 16 patients before the use of the L M A (Table 6). One case was abandoned as described above, one had partial airway obstruction and four required more than one attempt at insertion to achieve a satisfactory airway. The size 1 mask was only used on two occasions.
Discussion
Fig. 2. Photographic views as seen through the LMA of the laryngeal inlet. The vocal cords and arytenoids can be seen clearly on the left, while downfolding of the epiglottis beneath the fenestrations of the mask aperture has occurred on the right.
Table 6. Known airway problems.
Comments Partial obstruction abandoned after three attempts of insertion No problems Amyoplasia congenita Four had no problems. One had Apert’s syndrome, five cases excess secretions and required two attempts of insertion One had laryngospasm and Cleft palate, two cases required two attempts of insertion Had laryngospasm and required Tracheomalacia, post aortotwo attempts of insertion PexY Haemangioma of pharynx and No problems larynx No problems Multiple fibromatosis No problems Sleep apnoea upper airway obstruction Required two attempts of Haemangioma on lip insertion No problems Hydrocephalus and achondroplasia Partial obstruction Other
Subglottic stenosis
The various merits and limitations of the LMA in adults have been described.’ Our incidence of major problems that resulted in abandonment of its use (2.5%) is comparable with that reported by Minor problems, however, occurred more frequently in our study. Inadequate anaesthesia on insertion of the L M A may result in coughing, vomiting, and laryngospasm. Thus sufficient anaesthesia is essential and this appears to be greater than that required for insertion of a n oropharyngeal airway, but less than that for tracheal intubation. In some cases, particularly in children with tonsillar hypertrophy, insertion can prove difficult, but can be facilitated by ensuring that an antisialogue premedicant has been given, that the head is well extended, and that firm pressure of the device on the hard palate is applied in order to negotiate the posterior pharyngeal wall. Other manoeuvres can be employed to overcome this obstacle, namely by slight lateral insertion of the mask, by the use of a finger on the posterior wall of the mask acting as a guide, and by pulling the tongue forwards with a dry swab. Once inserted, accidental dislodgement can occur, especially in the younger child, where there is a substantial portion of the tube protruding from the mouth. Thus it is important to fix the L M A securely in place. Biting on the tube of the LMA during recovery can cause airway obstruction. This can be overcome by the use of a bite block such as Guedel airway which should be inserted at the same time as the L M A and also securely fixed in place. The device does not provide an absolute guarantee of a secure airway, or of laryngeal protection, since it does not provide a watertight seal and thus aspiration may occur in patients who are at risk of regurgitation of gastric contents. Similarly, many of the problems encountered on recovery appeared to be due to accumulation of secretions within the mask aperture.
Fig. 3. The size 2 laryngeal mask airway.
Forum Intermittent positive pressure ventilation via the LMA could potentially result in gastric inflation which, in children, will cause splinting of the diaphragm and compromise respiratory function. The lungs of two of the patients in the study were ventilated successfully, but further work will need to be performed to validate this technique in children. The LMA was used in several children with known difficult airways, but problems did occur. Hence great caution should be taken with these patients. It is important that alternative means to maintain an airway are available and that there is ready access to the patient’s head. We would not regard the device as the technique of choice for patients with known airway problems presenting for major head and neck surgery. We were interested to note that downfolding of the epiglottis does occur as feared in some cases. Surprisingly, this did not result in airway obstruction. Presumably this is because the area between the edges of the epiglottis and the rim of the mask aperture is sufficiently large to allow unobstructed ventilation. The LMA proved particularly suitable for the spontaneously breathing child as an alternative to the use of a mask and airway or tracheal tube. I t maintained a clear airway without the need for laryngoscopy and intubation and allowed both hands to be free. The size-2 L M A was remarkably versatile in that it could be used over a wide age range. The mask was well tolerated once in place, even at light planes of anaesthesia. Airway maintenance during recovery was facilitated. The device was removed once the patients were awake and had full return of their laryngeal reflexes. Connexion directly to a T-piece system provided an additional monitor of respiration whilst 100% oxygen was administered. As in adults, the LMA was particularly useful for minor head and neck procedures such as myringotomy and for peripheral limb, minor general and urogenital surgery in conjunction with a local anaesthetic block. We consider that the L M A provides the anaesthetist with
763
an additional aid in the management of the upper airway in children during spontaneous breathing. An adequate period of starvation is essential before its use, and an antisialogue premedicant should be given. Any method of induction is suitable for its insertion in children, but an adequate depth of anaesthesia is necessary. Secure fixation is important to prevent accidental dislodgement, and the use of an oropharyngeal airway one size smaller than for the age of the child acts as a good bite block. The size-2 L M A can be successfully used within a weight range of between 6 kg to 30 kg. Acknowledgments
The authors thank D r I.G. Johnston and all the members of the anaesthetic department at the Hospital for Sick Children, Great Ormond Street for their assistance during this study and D r J.S. Sherrard for her help in text preparation. References 1. BRAINAIJ. The laryngeal mask-a new concept in airway management. British Journal of Anaesthesia 1983; 55: 801-5. 2. BRAINAIJ, MCGHEETD, MCATEEREJ, THOMAS A, ABU-SAAD MAW, BUSHMANJA. The laryngeal mask airway. Development and preliminary trials of a new type of airway. Anaesthesia 1985; 4 0 35661. 3. BRODRICK PM, WEBSTERNR, NUNNJF. The laryngeal mask airway. A study of 100 patients during spontaneous breathing. Anaesthesia 1989; 44: 2 3 8 4 1 . 4. ALEXANDER CA, LEACHAB. The laryngeal mask-experience of its use in a district general hospital. Toduy’s Anaesthetist 1989; 4 20&5. 5. BRAINAIJ. Three cases of difficult intubation overcome by the laryngeal mask airway. Anaesthesia 1985; 40: 353-5. 6. BEVERIDGE ME. Laryngeal mask anaesthesia for repair of cleft palate. Anaesthesia 1989; 44: 656-7. 7. SMITHBL. Brain airway in anaesthesia for patients with juvenile chronic arthritis. Anaesthesia 1988; 43: 421.
Anaesthesia, 1990, Volume 45, pages 763-766 Intravenous diclofenac sodium Does its administration before operation suppress postoperative pain?
W. I. Campbell, MB, FFARCSI, Consultant, R. Kendrick, MB, FDS, FFD, Consultant Oral Surgeon, Department of Anaesthetics, The Ulster Hospital, Dundonald, Belfast BTI 6 ORH, C. Patterson, MSc, Lecturer in Medical Statistics, Queens University, Belfast.
Summary Intravenous diclofenac sodium was evaluated in a double-blind randomised trial relative to intramuscular diclofenac, intravenous jkntanyl, and intramuscular placebo in 160 patients undergoing extraction of impacted lower third molar teeth. The test drug was administered before operation in an attempt to alleviate postoperative pain. A 10-cm visual analogue scale was used to assess pain at 30 minutes and one day after surgery, if the patients stayed overnight. Patients who received intravenous diclofenac had significantly less pain than the other groups 30 minutes after operation. They also had signijicantly less pain one day after surgery than the placebo or opioid groups, but not less than the intramuscular diclofenac group. Capillary bleeding time, in comparison with placebo, was signifcantly prolonged after the use of intramuscular diclofenac. and a similar but nonsignijkant trend was observed in the intravenous diclofenac group. N o problems were encountered with excessive bleeding in any group. Key words: Analgesics; diclofenac, fentanyl. Pain; postoperative.
Accepted 23 January 1990.
