Abstract
As opposed to the simplistic promotion of one given technique or device, the multimodal airway management relies on the recognition that each individual approach may fail, that the maintenance of oxygenation during the procedure is a key point, that the prerequisites to the practical step of placing a tube in the trachea involve the knowledge of intelligent and intelligible algorithms and the previous acquisition of skills, with understanding of their foundations. An example of the ‘combination techniques’ using the specific advantages of one medical device to mitigate the limitations of another is the use of a videolaryngoscope to facilitate intubation with a flexible optical bronchoscope, which increases the ease and the success of the process during the clinical as well as the training phases. Other multimodal approaches such as the combination of bronchoscopy with the use of a supraglottic airway or with high flow nasal oxygen optimise the safety of the procedure by maintaining the delivery of oxygen. The multimodal approach is particularly useful for the anaesthesiologist and intensivist only occasionally exposed to the management of difficult airway situations. It improves high quality care of patients, education and training.
Combination Techniques: Development and Advantages
As described in other chapters, all techniques in airway management may fail and this risks harm to the patient. Despite advances in techniques such as the development and evolution of supraglottic airways (SGAs) and different modes of laryngoscopy each of these may fail. As these new techniques have been developed there has been an increasing realisation that procedural success is not our prime aim, and that airway management is not an end in itself, but only a means of delivering oxygen to the patient. Hand in hand with this has been adoption of techniques to enhance oxygenation during airway procedures.
There has also been a move away from focussing exclusively on prediction of difficult intubation and towards an emphasis on how to manage it when it occurs. Current thinking focusses primarily on what to do in the event of difficulty, rather than simply knowing that something will have to be done.
Advances in mechanics, optics and ultrasonography, combined with the development of intelligent and intelligible algorithms by airway societies, have created multiple opportunities for the modern airway manager.
Accepting that each individual step of the process of airway management may fail offers the opportunity to combine techniques into ‘combination techniques’ that use the specific advantages of one medical device to mitigate the limitations of another.
The most obvious example is the use of a videolaryngoscope (VL) to facilitate intubation with a flexible optical bronchoscope (FOB). We will present this technique in detail.
Other multimodal approaches are based on a combination of FOB intubation with (i) direct laryngoscopy, (ii) an SGA or (iii) a specially designed face mask such as a Fibroxy or VBM mask. The latter two combinations differ from those aimed solely at facilitating tracheal intubation in that they optimise the safety of the procedure by maintaining the delivery of oxygen to the patient. The combination of high flow nasal oxygen (HFNO) and bronchoscopy can be included in the same group. Further examples are included in the list of Further Reading.
The multimodal approach is also suitable for FOB training where textbook knowledge is combined with computer-based virtual reality training, and simulations encompassing the development of non-technical and teamwork skills before the student ultimately engages in clinical practice under the guidance of a tutor.
Difficulties in Routine Acquisition of Flexible Optical Bronchoscopy Skills
Awake FOB-guided intubation is still the standard technique for management of predictable difficulties in mask ventilation and tracheal intubation. Although the possibility of abandoning it in favour of videolaryngoscopy has been discussed on occasion, this has rightly now been largely dismissed in the recent literature and with increasing availability of relevant technology there is even the possibility to expand opportunities.
Despite anaesthetists being required to master FOB-guided intubation, opportunities for practice are limited: the absolute number of patients with a predicted difficult airway is low, and the availability and fragility of equipment, hygiene issues and the risk of transmitting infectious diseases have all been limiting factors. As a result, many anaesthetists complete their initial training without acquiring FOB skills properly and with few opportunities to practise and are in real danger of losing their skills.
There are various solutions to these training issues: the advent of single-use endoscopes has largely resolved the problems relating to equipment availability and hygiene. Extending the indications for FOB intubation beyond the scope of difficult airway management and cervical spine instability may be advisable as many patients with normal airways could benefit from the avoidance of the physiological stress of laryngoscopy (e.g. neonates and patients with hypertension, diabetes or cardiac disease).
Use of a multimodal approach is likely to increase the use of FOB-based intubation techniques, both benefitting patients and providing increased training and skill maintenance opportunities.
Learning the Multimodal Airway Management Concept with Virtual Reality
Traditionally the acquisition of FOB skills is based primarily on an understanding of the basic of scope manoeuvring (see Chapter 16) and on initial learning using a virtual reality simulator or navigator as a part-task trainer. Simulation optimises the subsequent clinical practice of FOB-guided intubation. High-fidelity simulators have limitations including cost and cumbersome logistics around their use. Low-fidelity simulators, such as home-made wooden panels with a selection of holes to choose from, are inexpensive and their educational effectiveness is comparable to that of high-fidelity devices. However, they still require logistic infrastructure including premises, a real FOB with connectors and a display screen and a team of motivated instructors. They do not allow students to familiarise themselves with the endoscopic anatomy of the human upper airways.
Virtual endoscopic software overcomes these limitations by enabling users to browse inside three-dimensional reconstructions of human CT/MRI scans. They are developed using the multimodal bronchoscopy model. For instance, the VFI program (Karl Storz, Tuttlingen, Germany, Figure 19.1) provides on two lateral screens: the three-dimensional reconstructed image of the whole airway and the corresponding X-ray image. The location of the tip of the virtual FOB is indicated on these two images with a red arrow. The main screen provides the image collected by the virtual FOB. Using the computer mouse, the trainee can perform a virtual progression through the airways from either the mouth or the nose into the trachea. The trainee benefits from a part-task schedule since they can first get used to the endoscopic airway anatomy. They can then easily acquire endoscopic psychomotor skills, as they constantly follow the position of the FOB tip along with the view obtained from this tip. Indeed, this is the ideal preparation for the clinical multimodal VL-FOB approach to intubation, where the anaesthetist can follow on a VL screen the position of the FOB, from outside this FOB, as the FOB provides the main endoscopic view on its own screen and is progressively introduced towards the carina (see below).
