1 London, UK 2 Liverpool, UK
EditorWe read with interest the abstracts on the learning curve for the Bonfils Intubation Fibrescope.1 2 As part of our specialist registrar airway module, we are encouraged to use various commercially available airway devices. We recently had on loan an Airway Management Set from Storz, which contains equipment for the management of the routine and difficult airways. One of the devices is the Bonfils retromolar intubation fibrescope, a narrow calibre rigid fibrescope with a distal anterior curve. We were interested to find that this instrument does not appear in standard airway textbooks. Bonfils appears to have described this technique but produced no written case series to support its use. There are no peer-reviewed papers in the English literature, but one German study gives results from 107 patients intubated with the Bonfils.3 Two abstracts (from the same group) presented to the Anaesthetic Research Society (ARS) have been published recently,1 2 and we would like to compare our clinical experience with their results.
The earlier abstract describes 16 patients intubated by one author with a 100% success rate and a mean intubation time of 69 s (range 34180 s).2 The later abstract details 60 patients intubated by two authors with one failure and a median intubation time of 33 s.1 There were no major problems described but jaw thrust was useful in several patients. Our clinical experience in 36 unselected patients (31 by P.W. and five by C.L.) has been less favourable with an overall successful intubation rate of 31/36 (86%) and median intubation time of 80 s (range 34282 s). Intubation time was defined as from the time from picking up the Bonfils to obtaining an appropriate capnograph trace after intubation. We found that jaw thrust by an assistant improved the view in 31% of patients; our two commonest problems have been with disengagement of the tube from its slide-cone locking collar (28%), and serious fogging of the view (11%). Fogging has been minimized by doubling the recommended rate of oxygen such that 6 litre min1 pass down the insufflating channel. Failure of intubation has been due to an inability to locate the laryngeal inlet in three patients, equipment failure in one patient, and oesophageal intubation in one patient due to great difficulty in disengaging the tube from the collar. One of the failures was in a patient with limited mouth opening (<2 finger breaths) for whom the Bonfils device is specifically recommended. Rigid fibrescopes have the general problem of secretions interfering with the view and need some mechanism of distracting the tissues to obtain a clear view. The Bonfils would appear to be particularly poor in its ability to retract tissues.
Our clinical experience would lead us to view the device as one which will not become a core skill but rather remain in the hands of enthusiasts. We are surprised that a device that has not been subjected to any comparative or large scale studies is found in an airway management set for difficult intubation. We would be interested to hear from other Bonfils users.
P. Wong
C. Lawrence
A. Pearce
London, UK
EditorThank you for the opportunity to reply to the correspondence from Wong and colleagues concerning our ARS abstracts on the Bonfils intubating fibrescope.1 2 Our full article relevant to this work will be published shortly in Anaesthesia. This paper will outline details of two separate techniques developed by us despite a preliminary visit to Leipzig to observe Dr Christian Rudolfs clinical practice. In addition to this experience, one of us (P.C.) had had numerous opportunities to observe trainees in various centres using the instrument with different types of manikin. It is now our firm view that the current commonly available manikins have a very limited place in training for this instrument; indeed some manikins are virtually incompatible with its correct use.
The main thrust of our abstract presentations was that the instrument is far from intuitive in use and we suggested a learning curve of 20 cases be considered appropriate. In our institution, we have clip-on cameras with monitor stacks in the anaesthetic rooms of all four head and neck theatres. This might suggest that the situation would be worse for others with less-favourable conditions. However, we believe that the techniques to be described in our full publication answer most of the problems reported by Wong and colleagues.
The principal constraint for all airway visualizing devices is the opening up of the oropharynx. In Wongs series, jaw thrust by an assistant was used in 31% of cases, while we only needed to do this in 5%. Rudolf3 used a Macintosh blade to insert the instrument in 20% of cases but still had an overall failure rate of 5%. (Some of these cases were known difficult intubations.) In our normal cases, we never used this blade to insert the Bonfils, but instead substantially relied on the left hand to distract the soft tissues and this was generally very effective. Even when a clear view of the laryngeal inlet is achieved, the curve on the instrument does not allow straightforward advancement. Rather a rotation movement to one side off the incisors is what moves the instrument along in the direction of the line of view. Once this aspect is mastered, use of the instrument becomes straightforward.
On occasion, we too found difficulty disengaging tracheal tubes from the locking device and have suggested to Storz that a disengaging push button be incorporated. Our answer to the problem of fogging was to either warm the instrument when cold or otherwise just to use a standard anti-fogging agent. We regard the problem of secretions as trivial in the sense that they become insignificant when the airway is suitably opened up and then, as for flexible fibrescopes, they can usually be skirted round. We have some difficulty with the notion that the Bonfils would appear to be particularly poor in its ability to distract the tissues. In our experience, one of the major advantages of the Bonfils relative to a flexible fibrescope is that the tissues can be distracted usefully, as for example in picking up or sliding beneath the epiglottis.
The more we use this instrument, the more impressed with it we become. However, we still agree that the overall position for the instrument remains open to question. It takes time to learn and we need to know whether this is worth this effort. There is still insufficient experience with the Bonfils to know how often it will prove successful when it really counts. A flexible fibrescope is not necessarily intuitive and many have commented on the time taken to both learn the instrument in the first place and then to maintain skills for the threatening situations. Our experience thus far of a limited number of cases of known difficulty has been extremely encouraging.
Wong and colleagues allude to the problem of a manufacturer bringing to the market a device that has very limited proof of clinical efficacy. In general, we support this view wholeheartedly and there is no excuse for this happening for any new equipment in the current climate. The history of the Bonfils scope is unusual and rather obscure because according to contacts in the company it was designed and first manufactured over 20 years ago. It was originally intended for ear, nose and throat (ENT) use and apparently is still used by the original designer in his normal ENT practice. Although the instrument did not come into general use at the time, it was left in the companys catalogue and rediscovered by Dr Christian Rudolf after the re-unification of Germany. In our view, the Bonfils certainly warrants a comprehensive re-evaluation. For the moment, we are very happy to be described as enthusiasts or even, by implication, skilled enthusiasts.
P. Charters
M. Halligan
Liverpool, UK
References
1 Halligan M, Charters P. Learning curve for the Bonfils intubation fibrescope. Br J Anaesth 2003; 90: 826P
2 Halligan M, Weldon B, Charters P. A clinical appraisal of the Bonfils intubating fibrescope. Br J Anaesth 2002; 89: 6712P
3 Rudolph C, Schlender M. Klinische Erfahrungen mit der fiberoptischen intubation mit dem intubationfiberskop nach Bonfils. Anaesthesiol Reanim 1996; 21: 12730[Medline]