Anuesthesiu, 1992, Volume 47, pages 878-881 APPARATUS
An evaluation of the gum elastic bougie Intubation times and incidence of sore throat
J. P. NOLAN
AND
M . E. WILSON
Summary This study was designed to evaluate the routine use of a gum elastic bougie for tracheal intubation. The median time to intubation with the gum elastic bougie while simulating an 'epiglottis only' view was only 10 s longer than the time taken during conventional intubation with an optimum view. Three of the patients required a gum elastic bougie-assisted intubation after attempts at conventional visual intubation had,failed. There was no significant difference in the incidence of postoperative sore throar und hoarseness between the two groups. We recommend that anaesthetists should use the gum elasric bougie whenever a good view of the glottis is not immediately obtained.
Key words Intubation; gum elastic bougie. Complications; sore throat.
Tracheal intubation is usually performed under direct vision with the Macintosh laryngoscope. In some patients, despite correct positioning of the head and neck and backward pressure on the larynx, considerable pressure may have to be exerted with the laryngoscope to achieve even a glimpse of the vocal cords. If the laryngeal aperture cannot be seen, intubation may require several attempts and may result in damaged teeth or end in failure. In these circumstances the technique of intubating over a gum elastic bougie, first described by Macintosh in 1949 [I], is often successful [2]. This has become a popular technique with British anaesthetists when intubation proves difficult. However, it might be sensible to resort to the use of a gum elastic bougie more readily if there is any difficulty whatsoever in seeing the cords. Anaesthetists might be more willing to employ this technique if it can be shown that the intubation time is not appreciably prolonged by it, and that it is not associated with unacceptable complications. This study was designed to compare intubation times with and without the gum elastic bougie, and to establish whether or not use of the device is associated with an increase in the incidence of sore throat or hoarseness postoperatively .
Methods Ethics committee approval was obtained. One hundred and fifty-two patients, ASA grades 1-3, who required tracheal intubation as part of the anaesthetic technique for elective
surgery, were studied. Patients were either premedicated with temazepam or received no medication. lntubations were performed by the authors, both of them experienced anaesthetists. Patients less than 16 years old, and those requiring a rapid sequence induction, were not studied. Patients were positioned in the 'sniffing' position, with one pillow under the head. Anaesthesia was induced intravenously and neuromuscular blockade was achieved with either suxamethonium 1 mg.kg-' or vecuronium 0.1 mg.kg.-'. Intubation was attempted I min after giving suxamethonium and 3 min after vercuronium. This provided adequate muscle relaxation for laryngoscopy in all patients. Patients' lungs were ventilated manually using a Magill breathing system. An initial laryngoscopy, with a size three Macintosh blade, was performed in order to grade the amount of larynx seen [3]. If necessary, laryngeal manipulation was used to improve the view: grade 1, at least some of the glottis can be exposed; grade 2, only the arytenoids can be exposed; grade 3, the glottis cannot be exposed, but the epiglottis can be seen; grade 4, neither the glottis nor epiglottis can be seen. After the amount of larynx seen was classified, the laryngoscope was removed and the patient randomly allocated to either intubation under direct vision (visual group) or intubation over a 15 Ch gum elastic bougie (Eschmann Healthcare, Lancing, West Sussex, UK) (bougie group). Because the grade of laryngoscopy is the most important factor influencing the ease of intubation, patients were stratified according to grade and then randomised using a
J.P. Nolan, FRCAnaes, Senior Registrar, M.E. Wilson, PhD, FRCAnaes, Consultant, Department of Anaesthesia, Royal United Hospital, Combe Park, Bath BAI 3NG. Accepted 6 February 1992. 0003-2409/92/010878
+04 S08.00/0
@ 1992 The Association of Anaesthetists of G t Britain and Ireland
878
Evaluation of the gum elastic bougie
8 79
Time ( s )
Fig. 1. (a) Intubation times for the visual group. The failures were successfully intubated with the aid of a bougie. (b) Intubation times for the bougie group when difficult intubation was simulated. Grades at initial laryngoscopy: W, grade 3; 0,grade 2; 0 , grade I .
minimisation technique [4]. This ensured that approximately equal numbers of patients were allocated to each method of intubation for each grade of laryngoscopy. In the visual group of patients the laryngoscope was again used to get the best view of the larynx, and the patient was intubated with a Curity (The Kendall Company, Mansfield, M A 02048, USA) cuffed tracheal tube of either 8 mm internal diameter for men or 7 mm for women. A stop watch was started the moment the anaesthetist took the laryngoscope from the assistant, and stopped when successful intubation was confirmed with Wee’s oesophageal detector [5]. In the operating theatre, correct placement of the tube in the trachea was confirmed by auscultation and capnography. If intubation was unsuccessful after two attempts, a gum elastic bougie was used. In the bougie group of patients, a stop watch was started as soon as the anaesthetist took the laryngoscope. This was used to expose the epiglottis only. A well-lubricated gum elastic bougie ( 1 5 Ch) was passed behind the epiglottis and correct placement was indicated by (a) feeling clicks as the bougie slid over tracheal rings [6,7] or (b) rotation of the bougie as it entered a main bronchus or (c) hold up of the bougie as it reached the small bronchi [6,7]. Once located in the trachea, the bougie was steadied by an assistant, and with the laryngoscope still held in the mouth, the tracheal
tube was gently ‘rail-roaded’ over the top. Just before the tube was passed through the cords, it was rotated a quarter-turn anticlockwise, so that the bevel faced posteriorly. This manoeuvre, performed while still keeping the laryngoscope in the mouth, has been shown to improve the rate of successful first-time intubation [&lo]. The bougie was then withdrawn and, once successful tracheal intubation was confirmed with the Wee detector, the watch was stopped. Patients were interviewed the next day using a standardised interview format: (1) Was your anaesthetic alright? (2) Do you have or have you had a sore throat? (3) Do you have or have you had a hoarse voice? The patients responses to questions 2 and 3 were recorded as nil, slight, moderate, or severe.
Results The best initial views at laryngoscopy (with backward pressure on the larynx if necessary) were grade 1 in 114 (75%) patients; grade 2 in 27 (18%) patients; grade 3 in I 1 (7%) patients, and grade 4 in none of the patients. Histograms of the times taken for intubation are displayed in Figures I(a) and (b). The medians and ranges are presented in Table 1. Overall the visual technique is
880
J.P. Nolan and M.E. Wilson Table 1. Intubation times.
Number
Median
Range
6) All grades Visual group Bougie group Grade I Visual group Bougie group Grade 2 Visual group Bougie group Grade 3 Visual group Bougie group
(s)
74 75
18 28
10-90 17-1 10
58 56
17 25
10-90 17-60
13; 13
22 30
16-79 21-79
31 32
27-3 1 23-110
3t
6
.
*An additional patient was intubated with the gum elastic bougie after failing twice with the visual technique. ?An additional two patients were intubated with the gum elastic bougie after failing twice with the visual technique. Table 2. Incidences of sore throat and hoarse voice (n = 139).
Nil (Yo) Sore throat Visual group Bougie group Hoarse voice Visual group Bougie group
Slight (Yo)
Moderate
Severe
(YO)
(”/I
48 (67) 16 (22) 40 (60) 23 (34)
4 (6) 3 (4)
4
52 (72) 51 (76)
3 (4) 5 (7)
1 0
16 (22) 1 1 (16)
1
quicker (Mann-Whitney U test, p c 0.001). There was no appreciable difference in the median intubation times between the two anaesthetists (visual group 18 s vs 17 s, bougie group 25 s vs 26 s). Ninety percent of intubations were performed within 45 s, whichever technique was used. However, in the visual group, three patients could not be intubated despite two attempts (one laryngeal grade 2 and two grade 3), although intubation was subsequently successful in all three with the aid of the gum elastic bougie. All patients in the bougie group were successfully intubated and since in this group only the epiglottis was exposed, we were actually simulating difficult intubation [3]. Ninety-one percent of patients were followed up (Table 2). The incidence of moderate or severe sore throat in the visual group was 1 1.1 % compared with 6.0% in the bougie group (%YO confidence intervals 4.9-20.7% and 1.7-14.6% respectively). This difference is not significant (Chi-squared 0.6). The incidence of moderate or severe hoarseness was also similar, 5.6%, for the visual group and 7.5% for the bougie group, with 95% confidence intervals of 1 5 1 3 . 6 % and 2 5 1 6 . 6 % respectively. There were no other complaints or complications related to intubation.
Discussion The purpose of this study was to see if there are any problems associated with the routine use of the gum elastic bougie. If none were found, this technique might be especially suitable for patients in whom there is a risk of damage to the teeth or cervical spine. We found that with only the epiglottis exposed it takes, on average, about 10 s longer than the visual method, irrespective of the initial laryngeal grade. However, one can place little reliance upon
the difference in laryngeal grade 3 patients since only a few were studied. The incidence of sore throat or hoarseness did not differ from that produced by the conventional visual technique. We found that ‘clicks’ and ‘holdup’, two signs which have been previously reported as being indicative of tracheal placement of the bougie, were very reliable [6,7]. Tracheal clicks (as the tip of the bougie bounces off tracheal rings) are more readily detected if the angle made by this distal part of the bougie is increased to about 60”. In addition, we have added a further sign; that of rotation of the bougie as it enters a main bronchus. Once the gum elastic bougie had been correctly placed, there were no patients in whom the tracheal tube could not be railroaded into the trachea at the first attempt. This success rate probably reflects the fact that we left the laryngoscope in the mouth and rotated the tube 90” anticlockwise before passing it through the cords, recommendations that have been made in a previous study [9]. Failure rates of 25% and 52% have been quoted when the tube is not rotated [9,1 I]. In addition, we elected to use tracheal tubes with ‘floppy cuffs’, 1 mm smaller than the majority of anaesthetists would choose. Our times include confirmation of the position of the tube using a Wee detector and these therefore are slightly longer than those previously reported [ 121. The detector provided a convenient, quick endpoint to intubation, although correct placement was ultimately confirmed by capnography in all 152 patients. Patients were directly questioned about sore throat or hoarseness; direct questioning results in a higher reported incidence than spontaneous complaint [ 131. None of the patients in this study received anticholinergic premedication, which has been shown to increase the incidence of postoperative sore throat significantly [ 141. Intubation over a gum elastic bougie is not associated with an increase in the incidence of postoperative sore throat or hoarseness, contrary to previous suggestions [3,15,16]. Indeed, we suggest that repeated attempts to pass a tracheal tube through a poorly visualised larynx is more likely to damage the larynx than if a gum-elastic bougie is gently used at the outset. The conventional technique of intubation under direct vision with a Macintosh laryngoscope has its problems and we suggest that many of these can be overcome if the long gum elastic bougie is used more freely. It is difficult, if not impossible, to place an orotracheal tube correctly if the glottis cannot be seen. In our study, two patients could not be intubated for this reason. However, these two patients, and all six patients in the bougie group whose glottis could not be seen initially, were intubated without difficulty using the bougie. Even if the glottis can be seen, it may not be possible to pass the tube because of peg teeth or missing teeth. This occurred in one patient in the visual group who required a bougie. In addition another patient in the visual group took 90 s to intubate as a result of awkward upper teeth, despite having a grade 1 laryngeal view. Teeth are commonly damaged during attempts to see the vocal cords and pass the tube. For example, 52% of anaesthetists’ reports to the Medical Defence Union of the United Kingdom relate to dental damage [Iq. The risk of damage is minimised with the bougie technique, since only the epiglottis needs to be seen at laryngoscopy. It is not
Evaluation of the gum elastic bougie necessary to struggle beyond this point and risk damage to teeth and lips in order to improve the view. It is important to be able to predict a grade 3 laryngoscopy when using the visual technique so that alternative techniques can be planned and a more experienced anaesthetist can be called to assist if necessary. Unfortunately, the methods devised to predict difficult intubation are disappointing because of poor sensitivity and specificity [ 181, although recently Frerk claims better results if two tests are combined [19]. If the bougie technique is used pre-operative prediction becomes less of a problem because only the epiglottis need be seen. The incidence of being unable to see the epiglottis is 04.44% [l, 18,20,21] which is about 10 times less frequent than being unable to see the glottis. Unfortunately, it may also be difficult to predict the patient in whom there is no view of the epiglottis, since in the Oates study, two of these patients had Wilson risk-sums of 1 or less, and one was Mallampati class 1 [18]. If the bougie is seldom used, the anaesthetist and his assistant are not skilled in its use when it is most required. Patients with suspected injuries of the cervical spine who require immediate tracheal intubation ar: best intubated orally with the head and neck manually stabilised in the neutral position [22,23]. In this position the vocal cords may not be clearly seen, therefore rather than attempting to extend the head, with the inherent risk of injuring the spinal cord, it seems sensible routinely to accept a grade 2 or 3 view and use the gum elastic bougie to assist intubation. Although use of the gum elastic bougie may be increasing in the United Kingdom, it is less commonly used in the United States [24]. This may reflect a more widespread use of fibreoptic intubation in the latter country. Indeed, a recent description of a difficult intubation trolley, from the United States, listed four fibreoptic intubating scopes but did not include a single bougie [25]. The gum elastic bougie has the advantage of being considerably simpler and quicker to use [12]. When there is an unexpected difficult intubation in a patient with a compromised airway, fibreoptic intubation is likely to take too long. In conclusion, we recommend that anaesthetists should not struggle to see the whole laryngeal aperture. If the cords are not immediately visible, a gum elastic bougie should be used. References [I] MACINTOSH RR. An aid to oral intubation. British Medical Journal 1949; 1: 28.
88 1
AA. Difficult tracheal intubation. Anaesthesia [2] TOMLINSON 1985; 40:4 9 6 7 . [3] CORMACK RS, LEHANEJ. Difficult tracheal intubation in obstetrics. Anaesthesia 1984; 3 9 1105-1 1. [4] POCOCKSJ. Clinical Trials. Chichester: Wiley, 1983; 85-87. [5] WEEMYK. The oesophageal detector device. Assessment of a new method to distinguish oesophageal from tracheal intubation. Anaesthesia 1988; 4 3 27-9. [6] SELLERSWFS, JONES GW. Difficult tracheal intubation. Anaesthesia 1986; 41: 93. [7] KIDDJF, DYSONA, LATTOIP. Successful difficult intubation. Use of the gum-elastic bougie. Anaesthesia 1988; 43: 437-8. [8] COSSHAMPS. Difficult intubation. British Journal of Anaesthesia 1985; 57: 239. [9] D ~ G R AS, FALCONERR, LATTO 1P. Successful difficult intubation. Tracheal tube placement over a gum-elastic bougie. Anaesthesia 1990; 45: 774-6. COSSHAMPS. Gum elastic bougie and difficult intubation. Anaesthesia 1991; 46: 234. MARKSRJ. Successful difficult intubation. Anaesthesia 1991; 46: 72. SMITHJE, MACKENZIE AA, SCOTT-KNIGHT VCE. Comparison of two methods of fibrescope-guided tracheal intubation. British Journal of Anaesthesia 199 I ; 66:546-50. HARDING CJ, MCVEYFK. Interview method affects incidence of postoperative sore throat. Anaesthesia 1987; 4 2 1104-7. VALENTINE S, MCVEYFK, COEA. Postoperative sore throat. A comparison after premedication with papavereturn/ hyoscine or temazepam. Anaesthesia 1990; 4 5 306-8. SMITHM, BUST RJ, MANSOURNY. A simple method to facilitate difficult intubation. Canadian Journal of Anaesthesia 1990; 37: 1 4 4 5 . DOGRAS, FALCONER R, LATTO IP. Successful difficult intubation. A reply. Anaesthesia 1991; 46: 72-3. UTTINGJE. Pitfalls in anaesthetic practice. British Journal of Anaesthesia 1987; 5 9 877-90. OATESJDL, MACLEOD AD, OATFS PD, PEARSALL FJ, HOWIE JC, MURRAY GD. Comparison of two methods for predicting difficult intubation. British Journal of Anaesthesia 1991; 66: 305-9. FRERKCM. Predicting difficult intubation. Anaesthesia 1991; 46: 1005-8. WILLIAMS KN, CARLIF, CORMACK RS. Unexpected, difficult laryngoscopy: a prospective survey in routine general surgery. British Journal of Anaesthesia 199 1 ; 66:38-44. WILSONME, SPIEGELHALTER D, ROBERTSON JA, LESSERP. Predicting difficult intubation. British Journal of Anaesthesia 1988; 61: 21 1-6. HASTINGS RH, MARKSJD. Airway management for trauma patients with potential cervical spine injuries. Anesthesia and Analgesia 1991; 73: 471-82. SUDERMAN VS, CROSBY ET, LUIA. Elective oral intubation in cervical spine-injured adults. Canadian Journal of Anaesthesia 1991; 38:785-9. MCCARROLL SM, LAMONT BJ, BUCKLAND MR, YATESAPB. The gum-elastic bougie: old but still useful. Anesthesiology 1988; 68: 643-4. LARSONCP. Difficult intubation cart. Journal of Clinical Anesthesia 1990; 2 432-3.
An evaluation of the gum elastic bougie Intubation times and incidence of sore throat
J. P. NOLAN
AND
M . E. WILSON
Summary This study was designed to evaluate the routine use of a gum elastic bougie for tracheal intubation. The median time to intubation with the gum elastic bougie while simulating an 'epiglottis only' view was only 10 s longer than the time taken during conventional intubation with an optimum view. Three of the patients required a gum elastic bougie-assisted intubation after attempts at conventional visual intubation had,failed. There was no significant difference in the incidence of postoperative sore throar und hoarseness between the two groups. We recommend that anaesthetists should use the gum elasric bougie whenever a good view of the glottis is not immediately obtained.
Key words Intubation; gum elastic bougie. Complications; sore throat.
Tracheal intubation is usually performed under direct vision with the Macintosh laryngoscope. In some patients, despite correct positioning of the head and neck and backward pressure on the larynx, considerable pressure may have to be exerted with the laryngoscope to achieve even a glimpse of the vocal cords. If the laryngeal aperture cannot be seen, intubation may require several attempts and may result in damaged teeth or end in failure. In these circumstances the technique of intubating over a gum elastic bougie, first described by Macintosh in 1949 [I], is often successful [2]. This has become a popular technique with British anaesthetists when intubation proves difficult. However, it might be sensible to resort to the use of a gum elastic bougie more readily if there is any difficulty whatsoever in seeing the cords. Anaesthetists might be more willing to employ this technique if it can be shown that the intubation time is not appreciably prolonged by it, and that it is not associated with unacceptable complications. This study was designed to compare intubation times with and without the gum elastic bougie, and to establish whether or not use of the device is associated with an increase in the incidence of sore throat or hoarseness postoperatively .
Methods Ethics committee approval was obtained. One hundred and fifty-two patients, ASA grades 1-3, who required tracheal intubation as part of the anaesthetic technique for elective
surgery, were studied. Patients were either premedicated with temazepam or received no medication. lntubations were performed by the authors, both of them experienced anaesthetists. Patients less than 16 years old, and those requiring a rapid sequence induction, were not studied. Patients were positioned in the 'sniffing' position, with one pillow under the head. Anaesthesia was induced intravenously and neuromuscular blockade was achieved with either suxamethonium 1 mg.kg-' or vecuronium 0.1 mg.kg.-'. Intubation was attempted I min after giving suxamethonium and 3 min after vercuronium. This provided adequate muscle relaxation for laryngoscopy in all patients. Patients' lungs were ventilated manually using a Magill breathing system. An initial laryngoscopy, with a size three Macintosh blade, was performed in order to grade the amount of larynx seen [3]. If necessary, laryngeal manipulation was used to improve the view: grade 1, at least some of the glottis can be exposed; grade 2, only the arytenoids can be exposed; grade 3, the glottis cannot be exposed, but the epiglottis can be seen; grade 4, neither the glottis nor epiglottis can be seen. After the amount of larynx seen was classified, the laryngoscope was removed and the patient randomly allocated to either intubation under direct vision (visual group) or intubation over a 15 Ch gum elastic bougie (Eschmann Healthcare, Lancing, West Sussex, UK) (bougie group). Because the grade of laryngoscopy is the most important factor influencing the ease of intubation, patients were stratified according to grade and then randomised using a
J.P. Nolan, FRCAnaes, Senior Registrar, M.E. Wilson, PhD, FRCAnaes, Consultant, Department of Anaesthesia, Royal United Hospital, Combe Park, Bath BAI 3NG. Accepted 6 February 1992. 0003-2409/92/010878
+04 S08.00/0
@ 1992 The Association of Anaesthetists of G t Britain and Ireland
878
Evaluation of the gum elastic bougie
8 79
Time ( s )
Fig. 1. (a) Intubation times for the visual group. The failures were successfully intubated with the aid of a bougie. (b) Intubation times for the bougie group when difficult intubation was simulated. Grades at initial laryngoscopy: W, grade 3; 0,grade 2; 0 , grade I .
minimisation technique [4]. This ensured that approximately equal numbers of patients were allocated to each method of intubation for each grade of laryngoscopy. In the visual group of patients the laryngoscope was again used to get the best view of the larynx, and the patient was intubated with a Curity (The Kendall Company, Mansfield, M A 02048, USA) cuffed tracheal tube of either 8 mm internal diameter for men or 7 mm for women. A stop watch was started the moment the anaesthetist took the laryngoscope from the assistant, and stopped when successful intubation was confirmed with Wee’s oesophageal detector [5]. In the operating theatre, correct placement of the tube in the trachea was confirmed by auscultation and capnography. If intubation was unsuccessful after two attempts, a gum elastic bougie was used. In the bougie group of patients, a stop watch was started as soon as the anaesthetist took the laryngoscope. This was used to expose the epiglottis only. A well-lubricated gum elastic bougie ( 1 5 Ch) was passed behind the epiglottis and correct placement was indicated by (a) feeling clicks as the bougie slid over tracheal rings [6,7] or (b) rotation of the bougie as it entered a main bronchus or (c) hold up of the bougie as it reached the small bronchi [6,7]. Once located in the trachea, the bougie was steadied by an assistant, and with the laryngoscope still held in the mouth, the tracheal
tube was gently ‘rail-roaded’ over the top. Just before the tube was passed through the cords, it was rotated a quarter-turn anticlockwise, so that the bevel faced posteriorly. This manoeuvre, performed while still keeping the laryngoscope in the mouth, has been shown to improve the rate of successful first-time intubation [&lo]. The bougie was then withdrawn and, once successful tracheal intubation was confirmed with the Wee detector, the watch was stopped. Patients were interviewed the next day using a standardised interview format: (1) Was your anaesthetic alright? (2) Do you have or have you had a sore throat? (3) Do you have or have you had a hoarse voice? The patients responses to questions 2 and 3 were recorded as nil, slight, moderate, or severe.
Results The best initial views at laryngoscopy (with backward pressure on the larynx if necessary) were grade 1 in 114 (75%) patients; grade 2 in 27 (18%) patients; grade 3 in I 1 (7%) patients, and grade 4 in none of the patients. Histograms of the times taken for intubation are displayed in Figures I(a) and (b). The medians and ranges are presented in Table 1. Overall the visual technique is
880
J.P. Nolan and M.E. Wilson Table 1. Intubation times.
Number
Median
Range
6) All grades Visual group Bougie group Grade I Visual group Bougie group Grade 2 Visual group Bougie group Grade 3 Visual group Bougie group
(s)
74 75
18 28
10-90 17-1 10
58 56
17 25
10-90 17-60
13; 13
22 30
16-79 21-79
31 32
27-3 1 23-110
3t
6
.
*An additional patient was intubated with the gum elastic bougie after failing twice with the visual technique. ?An additional two patients were intubated with the gum elastic bougie after failing twice with the visual technique. Table 2. Incidences of sore throat and hoarse voice (n = 139).
Nil (Yo) Sore throat Visual group Bougie group Hoarse voice Visual group Bougie group
Slight (Yo)
Moderate
Severe
(YO)
(”/I
48 (67) 16 (22) 40 (60) 23 (34)
4 (6) 3 (4)
4
52 (72) 51 (76)
3 (4) 5 (7)
1 0
16 (22) 1 1 (16)
1
quicker (Mann-Whitney U test, p c 0.001). There was no appreciable difference in the median intubation times between the two anaesthetists (visual group 18 s vs 17 s, bougie group 25 s vs 26 s). Ninety percent of intubations were performed within 45 s, whichever technique was used. However, in the visual group, three patients could not be intubated despite two attempts (one laryngeal grade 2 and two grade 3), although intubation was subsequently successful in all three with the aid of the gum elastic bougie. All patients in the bougie group were successfully intubated and since in this group only the epiglottis was exposed, we were actually simulating difficult intubation [3]. Ninety-one percent of patients were followed up (Table 2). The incidence of moderate or severe sore throat in the visual group was 1 1.1 % compared with 6.0% in the bougie group (%YO confidence intervals 4.9-20.7% and 1.7-14.6% respectively). This difference is not significant (Chi-squared 0.6). The incidence of moderate or severe hoarseness was also similar, 5.6%, for the visual group and 7.5% for the bougie group, with 95% confidence intervals of 1 5 1 3 . 6 % and 2 5 1 6 . 6 % respectively. There were no other complaints or complications related to intubation.
Discussion The purpose of this study was to see if there are any problems associated with the routine use of the gum elastic bougie. If none were found, this technique might be especially suitable for patients in whom there is a risk of damage to the teeth or cervical spine. We found that with only the epiglottis exposed it takes, on average, about 10 s longer than the visual method, irrespective of the initial laryngeal grade. However, one can place little reliance upon
the difference in laryngeal grade 3 patients since only a few were studied. The incidence of sore throat or hoarseness did not differ from that produced by the conventional visual technique. We found that ‘clicks’ and ‘holdup’, two signs which have been previously reported as being indicative of tracheal placement of the bougie, were very reliable [6,7]. Tracheal clicks (as the tip of the bougie bounces off tracheal rings) are more readily detected if the angle made by this distal part of the bougie is increased to about 60”. In addition, we have added a further sign; that of rotation of the bougie as it enters a main bronchus. Once the gum elastic bougie had been correctly placed, there were no patients in whom the tracheal tube could not be railroaded into the trachea at the first attempt. This success rate probably reflects the fact that we left the laryngoscope in the mouth and rotated the tube 90” anticlockwise before passing it through the cords, recommendations that have been made in a previous study [9]. Failure rates of 25% and 52% have been quoted when the tube is not rotated [9,1 I]. In addition, we elected to use tracheal tubes with ‘floppy cuffs’, 1 mm smaller than the majority of anaesthetists would choose. Our times include confirmation of the position of the tube using a Wee detector and these therefore are slightly longer than those previously reported [ 121. The detector provided a convenient, quick endpoint to intubation, although correct placement was ultimately confirmed by capnography in all 152 patients. Patients were directly questioned about sore throat or hoarseness; direct questioning results in a higher reported incidence than spontaneous complaint [ 131. None of the patients in this study received anticholinergic premedication, which has been shown to increase the incidence of postoperative sore throat significantly [ 141. Intubation over a gum elastic bougie is not associated with an increase in the incidence of postoperative sore throat or hoarseness, contrary to previous suggestions [3,15,16]. Indeed, we suggest that repeated attempts to pass a tracheal tube through a poorly visualised larynx is more likely to damage the larynx than if a gum-elastic bougie is gently used at the outset. The conventional technique of intubation under direct vision with a Macintosh laryngoscope has its problems and we suggest that many of these can be overcome if the long gum elastic bougie is used more freely. It is difficult, if not impossible, to place an orotracheal tube correctly if the glottis cannot be seen. In our study, two patients could not be intubated for this reason. However, these two patients, and all six patients in the bougie group whose glottis could not be seen initially, were intubated without difficulty using the bougie. Even if the glottis can be seen, it may not be possible to pass the tube because of peg teeth or missing teeth. This occurred in one patient in the visual group who required a bougie. In addition another patient in the visual group took 90 s to intubate as a result of awkward upper teeth, despite having a grade 1 laryngeal view. Teeth are commonly damaged during attempts to see the vocal cords and pass the tube. For example, 52% of anaesthetists’ reports to the Medical Defence Union of the United Kingdom relate to dental damage [Iq. The risk of damage is minimised with the bougie technique, since only the epiglottis needs to be seen at laryngoscopy. It is not
Evaluation of the gum elastic bougie necessary to struggle beyond this point and risk damage to teeth and lips in order to improve the view. It is important to be able to predict a grade 3 laryngoscopy when using the visual technique so that alternative techniques can be planned and a more experienced anaesthetist can be called to assist if necessary. Unfortunately, the methods devised to predict difficult intubation are disappointing because of poor sensitivity and specificity [ 181, although recently Frerk claims better results if two tests are combined [19]. If the bougie technique is used pre-operative prediction becomes less of a problem because only the epiglottis need be seen. The incidence of being unable to see the epiglottis is 04.44% [l, 18,20,21] which is about 10 times less frequent than being unable to see the glottis. Unfortunately, it may also be difficult to predict the patient in whom there is no view of the epiglottis, since in the Oates study, two of these patients had Wilson risk-sums of 1 or less, and one was Mallampati class 1 [18]. If the bougie is seldom used, the anaesthetist and his assistant are not skilled in its use when it is most required. Patients with suspected injuries of the cervical spine who require immediate tracheal intubation ar: best intubated orally with the head and neck manually stabilised in the neutral position [22,23]. In this position the vocal cords may not be clearly seen, therefore rather than attempting to extend the head, with the inherent risk of injuring the spinal cord, it seems sensible routinely to accept a grade 2 or 3 view and use the gum elastic bougie to assist intubation. Although use of the gum elastic bougie may be increasing in the United Kingdom, it is less commonly used in the United States [24]. This may reflect a more widespread use of fibreoptic intubation in the latter country. Indeed, a recent description of a difficult intubation trolley, from the United States, listed four fibreoptic intubating scopes but did not include a single bougie [25]. The gum elastic bougie has the advantage of being considerably simpler and quicker to use [12]. When there is an unexpected difficult intubation in a patient with a compromised airway, fibreoptic intubation is likely to take too long. In conclusion, we recommend that anaesthetists should not struggle to see the whole laryngeal aperture. If the cords are not immediately visible, a gum elastic bougie should be used. References [I] MACINTOSH RR. An aid to oral intubation. British Medical Journal 1949; 1: 28.
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AA. Difficult tracheal intubation. Anaesthesia [2] TOMLINSON 1985; 40:4 9 6 7 . [3] CORMACK RS, LEHANEJ. Difficult tracheal intubation in obstetrics. Anaesthesia 1984; 3 9 1105-1 1. [4] POCOCKSJ. Clinical Trials. Chichester: Wiley, 1983; 85-87. [5] WEEMYK. The oesophageal detector device. Assessment of a new method to distinguish oesophageal from tracheal intubation. Anaesthesia 1988; 4 3 27-9. [6] SELLERSWFS, JONES GW. Difficult tracheal intubation. Anaesthesia 1986; 41: 93. [7] KIDDJF, DYSONA, LATTOIP. Successful difficult intubation. Use of the gum-elastic bougie. Anaesthesia 1988; 43: 437-8. [8] COSSHAMPS. Difficult intubation. British Journal of Anaesthesia 1985; 57: 239. [9] D ~ G R AS, FALCONERR, LATTO 1P. Successful difficult intubation. Tracheal tube placement over a gum-elastic bougie. Anaesthesia 1990; 45: 774-6. COSSHAMPS. Gum elastic bougie and difficult intubation. Anaesthesia 1991; 46: 234. MARKSRJ. Successful difficult intubation. Anaesthesia 1991; 46: 72. SMITHJE, MACKENZIE AA, SCOTT-KNIGHT VCE. Comparison of two methods of fibrescope-guided tracheal intubation. British Journal of Anaesthesia 199 I ; 66:546-50. HARDING CJ, MCVEYFK. Interview method affects incidence of postoperative sore throat. Anaesthesia 1987; 4 2 1104-7. VALENTINE S, MCVEYFK, COEA. Postoperative sore throat. A comparison after premedication with papavereturn/ hyoscine or temazepam. Anaesthesia 1990; 4 5 306-8. SMITHM, BUST RJ, MANSOURNY. A simple method to facilitate difficult intubation. Canadian Journal of Anaesthesia 1990; 37: 1 4 4 5 . DOGRAS, FALCONER R, LATTO IP. Successful difficult intubation. A reply. Anaesthesia 1991; 46: 72-3. UTTINGJE. Pitfalls in anaesthetic practice. British Journal of Anaesthesia 1987; 5 9 877-90. OATESJDL, MACLEOD AD, OATFS PD, PEARSALL FJ, HOWIE JC, MURRAY GD. Comparison of two methods for predicting difficult intubation. British Journal of Anaesthesia 1991; 66: 305-9. FRERKCM. Predicting difficult intubation. Anaesthesia 1991; 46: 1005-8. WILLIAMS KN, CARLIF, CORMACK RS. Unexpected, difficult laryngoscopy: a prospective survey in routine general surgery. British Journal of Anaesthesia 199 1 ; 66:38-44. WILSONME, SPIEGELHALTER D, ROBERTSON JA, LESSERP. Predicting difficult intubation. British Journal of Anaesthesia 1988; 61: 21 1-6. HASTINGS RH, MARKSJD. Airway management for trauma patients with potential cervical spine injuries. Anesthesia and Analgesia 1991; 73: 471-82. SUDERMAN VS, CROSBY ET, LUIA. Elective oral intubation in cervical spine-injured adults. Canadian Journal of Anaesthesia 1991; 38:785-9. MCCARROLL SM, LAMONT BJ, BUCKLAND MR, YATESAPB. The gum-elastic bougie: old but still useful. Anesthesiology 1988; 68: 643-4. LARSONCP. Difficult intubation cart. Journal of Clinical Anesthesia 1990; 2 432-3.
