Combination Techniques

Key Points

• Combining airway techniques takes advantage of the respective strengths of each device while minimizing their specific shortcomings when used alone.

• The multimodal approach is appropriate in the use of various airway devices, including oxygenation tools.

• The multimodal approach is useful for teaching, clinical practice, and maintenance of knowledge in airway management.

• The most common examples of advantageous combinations in the field of airway management are the facilitation of flexible scope intubation (FSI) with video-assisted laryngoscopy and the use of a supraglottic device as a guide for FSI.

• Using THRIVE (transnasal humidified rapid insufflation ventilatory exchange), oxygenation is of paramount interest in association with FSI.

Introduction

The technical approach to airway management is one of the core medical techniques, and tracheal or bronchial intubation is a major concern in anesthesia (both operating room and procedural areas), the intensive care setting, and during resuscitation. The importance of the subject is reflected by the number of societies dedicated specifically to airway management, such as the Society for Airway Management (SAM), the Difficult Airway Society (DAS), and the European Airway Management Society (EAMS), in addition to intensive care and pulmonology societies, anesthesiology and perioperative medicine societies, and societies specializing in otorhinolaryngologic and thoracic surgery, which also incorporate airway management.

The field has evolved considerably in recent decades, as evidenced by the programs of the many specialized airway meetings. The first change was to emphasize that airway management is not an end in and of itself but rather a means of delivering oxygen to a patient. Likewise, decisive progress has been made in the prevention of hypoxemia, which may occur to varying degrees during the performance of tracheal intubation. Major advances have been made regarding ventilation, from the introduction of supraglottic airways (SGAs) and the general acceptance of high-flow apneic oxygenation to the concept of protective ventilation. The second substantive change in the field of airway management was to not only focus on the predictive signs of difficult intubation but to better address all forms of difficulty with airway management. Current thinking focuses primarily on what to do in the event of difficulty rather than simply knowing that something will have to be done.

These major developments have been underpinned by the advent of mechanical, optical, and ultrasound-based techniques, which, as unimaginable as it might seem today, did not come into use until recently, as well as the widespread introduction of new methods in initial and continuing education, and the production of recommendations and of intelligent and intelligible algorithms resulting from reflection rather than the mere sequential alignment of existing means.

Therefore the “stop and think” approach, which is a necessary part of the overall strategy to resolve difficult situations, was applied to the specific matter of selecting the appropriate tools. It became apparent that, despite the progress brought about by the new systems, none of them were infallible, and it would be more beneficial to use them together rather than separately. This conclusion underpins the multimodal approach to upper airway management.

The 2013 ASA Practice Guidelines for Management of the Difficult Airway have recently been revised and published in Anesthesiology 136. The new guidelines include the use of combination techniques in both the adult and pediatric algorithms, either when the patient is awake or after induction of anesthesia, as part of the airway management strategy. The airway practitioner’s assessment and choice of techniques should be based on their prior experience, available resources (including equipment), availability and competency of help, and the context in which airway management will occur. As with all techniques, experience and practice in nonemergent settings stand to optimize success in all environments.

The consultants and members of participating organizations in the most recent guideline development strongly agree with the recommendation to identify a preferred sequence of noninvasive devices to use for airway management if a noninvasive approach is selected. The consultants strongly agree, and members of participating organizations agree or strongly agree, that if difficulty is encountered with individual techniques, combination techniques may be performed.

Combining systems is a general approach that can involve most of the medical tools available to us, particularly regarding flexible or rigid, steerable or nonsteerable airway management devices, either with or without optical properties. Thus the multimodal airway management strategy consists of using the specific advantages of one medical device to mitigate the limitations of another. Additionally, the placement of pressure on the thyroid cartilage (backward, upward, rightward pressure [BURP] maneuver) or the utilization of special endotracheal tubes (ETTs) (e.g., Endotrol, Parker Flex-Tip, etc.) may facilitate tracheal intubation when utilizing any combination technique.

The most prominent example in the literature is the use of a videolaryngoscope (VL) to facilitate intubation with a flexible intubation scope (FIS), which may result in improved intubation success. In a recent randomized controlled trial comparing video-assisted laryngoscopy (VAL) itself or combined with flexible bronchoscopy, Mazzinari and colleagues reported a greater first-attempt success rate with the combination technique than with VAL alone. It is this technique that this chapter will present in detail.

Other multimodal approaches are based on a combination of flexible scope intubation (FSI) with direct laryngoscopy (DL), second-generation SGAs, specially designed face masks (e.g., the VBM Endoscopy Mask), retrograde intubation, jet ventilation, or percutaneous tracheostomy. The use of conduits such as SGAs or endoscopy masks differs from those aimed solely at facilitating tracheal intubation in that they optimize the safety of the procedure by maintaining the delivery of oxygen to the patient. The combination of THRIVE (transnasal humidified rapid insufflation ventilatory exchange) and bronchoscopy can be included in the same group. A detailed and comprehensive review of multimodal procedures incorporating FSI can be found in Chapter 24 .

The multimodal approach, which is particularly useful in the clinical setting, is also suitable for FSI training where textbook knowledge is combined with computer-based virtual reality training and simulation training, encompassing the development of nontechnical and team working skills, before a trainee ultimately engages in clinical practice under the guidance of a tutor.

Additionally, there are other combination techniques that do not involve FSI, including DL or VAL in combination with an optical stylet, an intubation/extubation catheter, or retrograde intubation; SGA placement in combination with an optical stylet, an intubation/extubation catheter, or retrograde intubation; and DL or VAL in combination with SGA placement.

Difficulty With the Use of Flexible Endoscopy in Clinical Practice

Despite the increase in the number of available airway devices and techniques, awake FSI remains the standard method for airway management in the event of foreseeable difficulties in mask ventilation and tracheal intubation. The possibility of abandoning awake FSI in favor of VAL has been discussed but is no longer regarded as a serious option in the most recent literature. On the contrary, the extension of FSI indications to unexpected emergency situations was highlighted in the UK’s National Institute for Health and Care Excellence (NICE) Medical Technologies Guidance (MTG14) on the single-use aScope (Ambu, Ballerup, Denmark), which is described as “specially recommended for unexpected difficult airways.”

Despite anesthesiologists being required to master FSI, ^, opportunities for practice are limited: the absolute number of patients with predicted difficult airway management is low, and teaching FSI in patients with normal airways may be considered ethically arguable.

FSI teaching has been further limited by the availability and fragility of equipment, hygiene issues, and the risk of transmitting infectious diseases through nonconventional agents (i.e., prions), in particular.

Previous reports have suggested that many anesthesiologists have completed their initial training without acquiring FSI skills properly. In addition to the problems surrounding initial training, as many airway practitioners have few opportunities to practice flexible endoscopy, they 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 FSI beyond the scope of difficult airway management, and the classic indication of cervical spine instability, seems advisable for many patients with normal airways who could benefit from the avoidance of stress related to DL (neonates or adult patients with hypertension, diabetes, and coronary artery disease, in particular). Finally, initial training and the practical implementation of FSI in a clinical setting are largely facilitated by the multimodal approach.