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Keywords:

  • Equipment;
  • gum elastic bougie. Intubation;
  • tracheal

Abstract

  1. Top of page
  2. Abstract
  3. Methods
  4. Results
  5. Discussion
  6. Acknowledgments
  7. References

Summary Data were collected prospectively on the use of the gum elastic bougie in 200 patients. The bougie was successfully inserted into the trachea and tracheal intubation was accomplished in 199 cases. The bougie was inserted into the trachea at the first attempt in 178 cases. In nine cases (4.5%) a second, more experienced, clinician was required. In 173 cases, the grades of view were recorded before and after the application of laryngeal pressure; pressure improved the view in 80 cases (46%), had no effect in 89 (51%) and worsened the view in four cases (2%). Various recommendations for optimal external laryngeal pressure and use of the bougie were not followed on 15–64% of occasions. There is a need for better education in these techniques.

The gum elastic bougie is widely used in clinical practice in the UK. A survey in Cardiff in 1996 showed that all 30 clinicians who were questioned used the bougie as their first choice of technique when presented with an unexpected difficult intubation under general anaesthesia [1]. A recent publication compared the use of the bougie and the stylet as aids to the management of simulated difficult intubation [2]. It was recommended that a bougie should be used in preference to a stylet if a good view of the glottis was not immediately obtained. Because the bougie is commonly available and widely used in the UK, and the stylet is widely used in the USA, it was suggested that there could be a difference in the immediate success rates for intubation in the UK and the USA. It was also claimed that in the majority of cases of unexpected difficulty, intubation can be accomplished quickly using the bougie [2].

This assertion was vigorously contested by Benumof who stated that the claim was both untested and unjustified [3]. The claim was, however, supported both by individual clinical experience and by previous editorial comment. Indeed Wilson has written ‘The success of this simple tool has quietly but radically altered anaesthetic practice, as all that is now required is a view of the epiglottis: even when the cords cannot be seen, the tip of␣the gum elastic bougie can be slipped quickly behind the epiglottis, through the cords, and a tracheal tube railroaded over it into position’[4]. As inability to see the epiglottis is rare, many difficult intubations will fit into the clinical scenario described by Wilson. It was suggested in reply to Benumof that a prospective survey of the use of the bougie in clinical practice might shed more light on the subject [5].

We therefore decided to evaluate prospectively the incidence of successful intubation when using the gum elastic bougie.

Methods

  1. Top of page
  2. Abstract
  3. Methods
  4. Results
  5. Discussion
  6. Acknowledgments
  7. References

The project was submitted for ethical approval. It was decided that formal consent was not required because there was no modification of normal clinical practice. The survey was completed between October 1997 and August 1998.

A form was available for completion after a bougie had been used, recording patients' baseline data; tests used to predict difficult intubation; the reason for use of the bougie; the view of the laryngeal inlet before and after external laryngeal pressure (if used); features of insertion of the bougie into the trachea (including the presence of palpable clicks when the bougie's tip abuts the anterior tracheal rings and the hold-up that occurs when the bougie impacts in the lung) and placement of the tracheal tube over the bougie; ventilation problems; and what was␣done if intubation failed. A modification [6] of the conventional Cormack & Lehane [7] classification of grades of laryngeal view was used (grade 1, whole larynx visible; grade 2a, partial view of vocal cords; grade 2b, only arytenoids visible; grade 3a, only epiglottis visible; grade 3b, epiglottis visible but closely applied to the posterior pharyngeal wall; grade 4, no part of larynx visible). The forms were placed in transparent folders in each anaesthetic room and the completed forms were collected regularly from an adjacent folder and scrutinised carefully. When omissions occurred, the clinician involved was approached in an attempt to complete the data. The incidence of use of the bougie was extracted from the Cardiff Anaesthetic Record system.

The effect of external laryngeal pressure was assessed using the Wilcoxon signed-rank test (statview Version 5.1), with a value for p < 0.05 taken to denote statistical significance.

Results

  1. Top of page
  2. Abstract
  3. Methods
  4. Results
  5. Discussion
  6. Acknowledgments
  7. References

Data were collected from 200 forms. Median (interquartile range [range]) age and weight of patients for whom these details were provided were 52 (44–64 [1–91]) years (n = 173) and 75 (65–86 [8–145]) kg (n = 175), respectively. Two children were included, one aged 1 year and weighing 8 kg and one aged 10 years and weighing 41 kg. A paediatric bougie was used in the 1-year-old. Of the 165 patients for whom sex was recorded, 88 were male and 77 female. Tests to predict difficulty were used (often in combination) on 168 patients (84%); these consisted of Mallampati score (138 cases), jaw movement (83 cases), neck movement (81 cases), thyromental distance (37 cases) and presence of irregular or vulnerable teeth (23 cases). Difficult intubation was predicted in 94 patients (47%).

Of the 200 intubations, 106 were performed by 58 different trainees who had been in practice 1.5–10 years; 94 intubations were performed by 27 different consultants who had been in practice 8–34 years. It was not possible to obtain the incidence of use of the bougie during the study period but it was used on 258 of a total of 6558 intubations (3.9%) for the 11 months from 1 January 1998 to 30 November 1998.

Reasons for using a bougie are shown in Table 1, with the laryngoscopic view and the effect of external laryngeal pressure (if used) shown in Tables 2 and 3. In some cases, laryngeal pressure was not used and in others, pressure was applied before induction of anaesthesia because the patients were at risk of aspiration. Data were available on who applied the laryngeal pressure in only 112 cases. In 72 of these (64%), pressure was applied by the assistant; in 19 cases (17%) by the anaesthetist alone and in 21 cases (19%) by both the anaesthetist and the assistant. There were three cases in which the only or final view was grade 4. In one case, the first view was grade 3b and after laryngeal pressure was grade 4. In two cases, the anatomy was destroyed by tumour. The bougie was passed at the first attempt and a tube was threaded over it at the first attempt in one of these two cases. There was no problem in maintaining an airway and no desaturation occurred in this patient. In the other case, four attempts were required to pass the bougie. One consultant tried twice with the bougie and failed. A second consultant tried once and failed. This consultant electively left the tracheal tube in the oesophagus and it was then possible to pass the bougie in front of this tube into the trachea.

Table 1.  Reasons for using the bougie in 200 patients. Values are number (proportion).
Poor view of larynx149 (74.5%)
Other (more than one reason in some cases)51 (25.5%)
Difficulty in pushing tube towards larynx46
Loose, irregular or crowned teeth7
Restricted neck movement2
Limited mouth opening1
Difficulty in pushing tube through the cords1
Table 3.  Change in grade of laryngoscopic view * after application of external laryngeal pressure in patients requiring use of the bougie because of poor view or other reasons (p < 0.001). Values are numbers of cases.
 Poor view (n = 138)Other reasons (n = 35)
  • *

    Grade 1, whole larynx visible; grade 2a, partial view of vocal cords; grade 2b, only arytenoids visible; grade 3a, only epiglottis visible; grade 3b, epiglottis visible but closely applied to posterior pharyngeal wall; grade 4, no part of larynx visible.

+320
+280
+15416
07118
−131
Table 2.  Grades of laryngoscopic view * before and after application of external laryngeal pressure in patients requiring use of the bougie because of (a) poor view or (b) other reasons. Values are numbers of cases .
  No laryngeal pressure appliedCricoid pressure applied before induction andLaryngeal pressure applied during laryngoscopy 
   laryngoscopyBeforeAfter
  • *

    Grade 1, whole larynx visible; grade 2a, partial view of vocal cords; grade 2b, only arytenoids visible; grade 3a, only epiglottis visible; grade 3b, epiglottis visible but closely applied to posterior pharyngeal wall; grade 4, no part of larynx visible.

  • No pressure was used because the anatomy was obscured by a fleshy tumour.

(a)10000
2a101435
2b323251
3a216938
3b012012
41†032
Total74138138
(b)170617
2a722417
2b0051
3a0000
3b0000
40000
Total1423535

In 20 cases (10%), other techniques were used before the bougie (Table 4). The bougie was inserted successfully into the trachea and the tube railroaded successfully over it in 199 of the 200 cases, mostly at the first attempt (Table 5). In one patient with a pharyngeal tumour, a grade 3b laryngoscopic view was obtained and the bougie was abandoned after the first attempt. The anaesthetist intubated using a fibreoptic scope without difficulty maintaining the airway or arterial desaturation. The tube was rotated anticlockwise during railroading in 155 cases (77.5%), usually by 90° but in one case by 180°; it was rotated clockwise in three cases and, in three other cases, a smaller tube was used. Information on whether the laryngoscope was left in the mouth when railroading the tube was available in only 133 cases; the laryngoscope was left in the mouth in 113 of these (85%). Clicks were elicited in 130 of the 199 successful cases (65%), in 109 cases without distal hold-up and in 21 with distal hold-up. In five cases, there was distal hold-up but no clicks. In 64 cases, neither clicks nor hold-up were obtained. Clicks were present in 108 (73%) of the poor-view cases and in 22 (43%) of the other cases.

Table 4.  Techniques attempted before use of the␣bougie␣for␣tracheal intubation in 20 of 200 patients. Values are actual number.
Patient repositioned9
McCoy blade used6
McCoy blade used  and patient repositioned1
Longer blade used1
Longer blade used and  patient repositioned1
Fibreoptic intubation attempted1
Cricoid pressure released1
Table 5.  Success rates for insertion of the gum elastic bougie and railroading the tracheal tube over it into the trachea in 200 patients. Values are number (proportion).
 Successful inserting bougieSuccessful railroading tracheal tube
  • *

    McCoy blade required in two cases and long blade in one case. More senior anaesthetist successful in two cases;

  • † bougie too rigid to pass on first two attempts in one case;

  • ‡ second anaesthetist required in all three cases.

First attempt178 (89%)184 (92.5%)
Second attempt15 (7.5%)*13 (6.5%)
Third attempt3 (1.5%)2 (1%)
Fourth attempt3 (1.5%)0
Failure1 (0.5%)

Arterial desaturation to < 95% occurred in eight patients. In one case the anaesthetist persisted at intubation attempts without ventilation; in one case a laryngeal mask airway was removed and the saturation was low at the start of tracheal intubation; in one case the tracheal tube entered the right main bronchus; in one case it entered the oesophagus on the first attempt; in one case there was difficulty pushing the tube towards the larynx before the bougie was used; and in one case there was difficulty passing the tube over the bougie (a second clinician successfully passed the tube after replacing the laryngoscope in the mouth). Difficulty with ventilation occurred in four patients, with desaturation < 95% in two of them. One had undergone hemiglossectomy 3 weeks previously. In these four patients, the bougie was inserted into the trachea and the tube threaded over it at the first attempt.

A second consultant was called for assistance or was involved in the management of nine cases: in seven because of difficulty inserting the bougie; and in two to assist with passing the tube over the bougie.

Discussion

  1. Top of page
  2. Abstract
  3. Methods
  4. Results
  5. Discussion
  6. Acknowledgments
  7. References

When using the bougie it is important to obtain the best possible laryngeal view and to bend the bougie in a curve so that it passes behind the epiglottis into the trachea. It is also necessary to be able to recognise that the bougie has passed into the trachea and not the oesophagus, and to railroad the tracheal tube over the bougie and confirm it to be in the correct place.

If there is a poor view of the laryngeal inlet, the anaesthetist should try and improve it. The head and neck should be placed in the classic position of lower cervical spinal flexion and full extension of the atlanto-occipital joint [8]. Optimal external laryngeal pressure should be applied with the laryngoscopist's right hand, which frequently improves the laryngeal view [9]. It has been stressed that this technique should be taught to every trainee and practised by all anaesthetists [9]. Our results generally indicate an improved view of the larynx after pressure was applied to the front of the neck. In 64% of cases, this pressure was applied by the assistant. However, in 89 of 173 (51%) cases, laryngeal pressure had no effect and in four cases the view worsened. Benumof & Cooper [9] recommended that pressure should initially be applied by the anaesthetist to obtain an optimal view of the laryngeal inlet. There is clearly a need to educate all anaesthetists in this technique. In addition, a different laryngoscope blade may be used. In the UK, the Macintosh blade is the most commonly used and the McCoy is also widely used if there are problems with intubation when using the former. However, there are those who support the use of straight blades [10, 11]. It has been stressed that ideally, ‘the first attempt at laryngoscopy should always be the best that one can make’[12]. In the UK, the bougie is usually tried before an alternative laryngoscope blade. The bougie should be used in an optimal way to maximise the chances of successful intubation. Cormack & Lehane [7] described the simulated difficult intubation drill in 1984. In this drill, the epiglottis is allowed to drop back simulating grade 3 views. The trainee can then practise the management of a patient presenting with such a view under calm circumstances. Cormack and colleagues later found that after suitable training with this technique, the incidence of failed intubation in their obstetric unit was 1:800 at a time when a figure of 1:300 was widely quoted [13].

In grade-3 views, when the bougie is passed blindly behind the epiglottis, it is important to recognise by the presence of clicks or distal hold-up that the bougie is in the trachea and not in the oesophagus [14]. The incidence of clicks should increase if the distal end of bougie is bent anteriorly. An additional, but less widely used, sign of successful tracheal placement is the natural rotation of the bougie as it enters a main bronchus [15]. However, neither the optimal angle of the bougie's distal end for entry into the trachea nor its optimal rigidity has been quantified. Anaesthetists usually bend the bougie to an angle that they hope will enable intubation to be accomplished without difficulty. A previous study demonstrated palpable clicks in 89.7% of cases of simulated difficult intubation [14]. In the present study, clicks were present in only 65.3% of cases and distal hold-up was present in 13%. It has been recommended that if clicks are present, the clinician should proceed with intubation; if they are not then the bougie should be advanced to a maximum distance of 45 cm. If hold-up occurs, the clinician should proceed with intubation [14]. In this study, a poor view of the larynx was present in ≈ 75% of the cases. If there is a good view it is not necessary to bend the bougie to the same extent as when there are grade 3a and 3b views and therefore the bougie is more likely to go down the centre of the trachea; the incidence of clicks would therefore be expected to be lower in these cases. The recommendation to rotate the tube anticlockwise [16] was followed in only 78% of cases. In one case, when the tube was not rotated, three attempts were made to pass the tube over the bougie before the tube could be railroaded into the trachea. The recommendation to leave the laryngoscope in the mouth [16] was followed in 85% of those cases for which this information was available. There was one case in which the bougie was too soft and one in which it was too rigid. Another rare cause of technical difficulty with use of the bougie is fracture of the outer varnish layer, sometimes unrecognised [17, 18]. It has been recommended that, before use, bougies should be carefully inspected for possible fractures [17] and tested for rigidity [18]. When the bougie is used it is important to minimise trauma. The bougie is flexible and if held near the proximal end, it will not transmit a great deal of␣force to the distal tip because it will bend easily. However, if the bougie is grasped more distally, much more force could be generated at the tip and trauma may occur. There are no recommendations as to where the bougie should be held for best results, or how many attempts should be permitted. The number of attempts at intubation will be influenced by the clinical circumstances and the skill of the clinician involved.

Once the bougie is in the trachea, the tube has to be railroaded over it. The best results are obtained if the laryngoscope is left in the mouth and the tube rotated 90° anticlockwise before passing it through the cords [16]. Inexperienced clinicians may fail to intubate when using the bougie and will need the assistance of more experienced clinicians. In nine of our 200 cases, a second clinician was involved and it is possible that the first would not have succeeded without help. Our results, however, support the view that if the bougie is used in an optimal way by experienced clinicians, the incidence of failure to intubate will be very low.

The preference for the bougie over the stylet in the UK has evolved over a number of years. A prospective investigation in 1984 showed that the bougie was used in only 45% of cases of difficult oral intubation and the stylet in 40% [19]. By 1990, a survey found that 90% of 51 anaesthetists used the bougie as a first-choice method and only 7.8% used the stylet [20]. A later survey in 1996 showed that 100% of the respondents used the bougie as the first-choice method for the management of unexpected difficult intubation [1]. A number of studies has shown that the bougie is effective in the management of simulated difficult intubation [2, 14, 15, 21]. There have also been case reports of both successful and unsuccessful use of the bougie. In a recent article, Cook [22] investigated the use of the bougie in a prospective series of 500 intubations. A high proportion of the patients had cervical spine pathology. The bougie was used in 106 cases (21.2%). It was used immediately when the vocal cords could not be seen and a 94.3% success rate was achieved. Other aids were only used if intubation could not be achieved after three attempts with the bougie and a standard Macintosh blade. Intubation was performed using the intubating laryngeal mask airway in three cases, the fibrescope in two cases and a bougie through a laryngeal mask airway in one case. Cook now uses the intubating laryngeal mask airway routinely if attempts with the bougie are unsuccessful (T.M. Cook, personal communication). Our higher success rate (99.5%) may be because we studied a different population; in addition, the bougie was also used in 51 cases in which a poor view of the larynx was not the reason for its use. It was not possible to measure the time taken in these clinical circumstances and we cannot therefore confirm that the bougie was passed quickly into the trachea. However, others have measured the time to intubate when using the bougie [15, 22].

With anticipated difficult intubation there is a choice between awake intubation, usually using a fibreoptic scope, or attempting intubation under general anaesthesia. In the UK, where many clinicians are lacking in fibreoptic skills, they either call for assistance or, more commonly, attempt intubation under general anaesthesia. For this latter group of clinicians, the optimal use of the bougie is of paramount importance. It appears that in the UK there is not enough emphasis on the teaching and practising of optimal laryngoscopy, external laryngeal pressure, use of the bougie and simulated difficult intubation. These important simple areas of activity are being neglected, whereas other complex aspects of airway management are commonly emphasised.

Mason commented in a recent editorial on the perception among UK trainees that the basic techniques are easy and not worthy of the meticulous disciplined approach they deserve [23]. Similar observations have been made by trainees from overseas [24]. Those responsible for training in the UK have a clear duty to teach the optimal use of the bougie as part of the initial management of any case of unexpected difficult intubation. Cormack has commented that repeatedly, junior trainees are put on the emergency rota at their previous hospital having never had any formal instruction on what to do if they could not see the cords (R.S. Cormack, personal communication). There has been a previous recommendation that the bougie should be used if the cords are not immediately visible [15]. Meticulous training in the optimal use of the bougie is a clear requirement if unnecessary problems are to be␣avoided. We certainly agree with comments made by Tunstall in 1989 relating to anaesthetic practice in the UK – that the single most useful piece of equipment for helping the anaesthetist to achieve success with a difficult intubation is the long gum elastic bougie [25].

The bougie is not included in the American Society of Anesthesiologists' algorithms [26] and it is not widely used in the USA. A recent USA survey showed that the bougie was chosen in < 5% of theoretical clinical scenarios and was frequently unavailable in anaesthetic locations, direct laryngoscopy and fibreoptic bronchoscopy being favoured [27]. However, fibreoptic skills and equipment will sometimes be lacking in the USA. If intubation fails with direct laryngoscopy using a stylet it is not clear what other simple technique should be used. It is probable that a lot of intubations in the USA using a fibrescope could be achieved successfully using the bougie. However, in the UK, fibreoptic technology is underused. The extent of morbidity and mortality resulting from attempts to intubate the trachea of patients with anticipated difficulty under general anaesthesia when fibreoptic skills are lacking in the UK is not known. Residents in the USA are closely supervised both at induction of anaesthesia and at the end of cases. In contrast, trainees in the UK are put on the emergency rota at a comparatively early stage in their training. The requirement for and timing of teaching different airway techniques appear to be different in the UK and the USA.

Acknowledgments

  1. Top of page
  2. Abstract
  3. Methods
  4. Results
  5. Discussion
  6. Acknowledgments
  7. References

We thank Emeritus Professor W.W. Mapleson for his helpful discussion and advice.

References

  1. Top of page
  2. Abstract
  3. Methods
  4. Results
  5. Discussion
  6. Acknowledgments
  7. References
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