Appropriate angled-tip front width facilitates tracheal tube introducer placement in difficult-to-displace epiglottis situations.

Tracheal tube introducers (TTIs) are a useful aid to a conventional laryngoscopy-intubation method of upper airway access in adults. However, even when TTIs are used, successful tracheal intubation is not guaranteed. Apart from suboptimal practice proficiency and unavailability of the complete repertoire of TTI, the physical attributes of the TTI have a role to play. Our report on the management of two cases highlights the importance of selecting a TTI with appropriate angled tip characteristics to facilitate successful guided intubation.

INTRODUCTION

Tracheal tube introducers (TTIs) have a proven role in the management of difficult airway situations.[12] In general, they facilitate conventional direct laryngoscopy-tracheal intubation before alternative airway equipment (laryngeal mask airway, fibreoptic bronchoscope, video laryngoscope, etc.) or technique is resorted to. However, since TTI are employed infrequently by anaesthesiologists (availability status, the inclination to use and practice proficiency),[23] their use may not always ensure predictable success. The cases described below elucidate an unexplored yet practical facet of TTI, whose knowledge is likely to enhance operational interest and successful access to the airway. Written informed consent from the patients was obtained after an elaborate explanation about the need for the case representation in the publication. Care has been exercised to preserve patient's identity in the case report.

CASE REPORTS

Case report 1

An unanticipated difficult airway was encountered in a 60-year-old female diabetic patient (60-kg, 148-cm) posted for total laparoscopic hysterectomy. On direct laryngoscopy (Macintosh#3 blade), a Cormack and Lehane grade-III view was achieved which could not be improved by head pillow width and head-and-neck positioning adjustments, laryngoscopic mandibular distraction and external laryngeal manipulation (ELM). The difficulty was the presence of a relatively small intraoral space and inability to move the tongue into the anterior mandibular space, and to lift the epiglottis adequately. We decided to use TTI to go around the epiglottis to enter the glottic opening. Face-mask ventilation was continued.

Additional propofol bolus was administered, and direct laryngoscopy was attempted again. This time, with the help of ELM, glottic-opening appeared as a narrow vertical slit to the right lateral edge of the difficult-to-move epiglottis. First, an Eschmann™ multiple-use introducer (Angled 15 CH × 600 mm, Smiths Medical International, Hythe, Kent, UK) was tried but failed to enter the trachea around the right epiglottic margin as its angled-tip got bent on each attempt to pass the glottic-opening. Thereafter, a rigid blue TTI (Angled 15 CH × 600 mm, Hansraj Nayyar Medical, Mumbai 400021, India), easily negotiated through the glottic-opening, but failed to advance despite axial and rotational adjustments. Based on author's (AD) practice experience (n = 728, 6.5-year), there is always some resistance on railroading forward and/or retrieving a tracheal tube over TTI with angled-tip design, the TTI's angled-tip front width was zeroed in as a crucial factor responsible for the failure of intra-tracheal advancement. Based on the above, the selection of another rigid TTI-variant, the 'new' Portex™ introducer (Angled 15 CH × 700 mm, Portex Tracheal Tube Introducer™, Smiths Medical International) with a lower angled-tip front width resulted in successful glottic entry and free intratracheal advancement. The railroading of cuffed tracheal-tube (ID. 6.0-mm) over the TTI posed no difficulty.

Case report 2

An unanticipated airway difficulty was encountered in a 34-year-old female patient (70-kg, 152-cm, ASA physical status-I) scheduled for spine decompression surgery (L4–5 discectomy, interbody fusion). Direct laryngoscopy with Macintosh#3 blade revealed a Cormack and Lehane grade-III view with a relatively large and hypermobile epiglottis. Each time attempts to lift the epiglottis for vocal cords visualisation proved problematic. When the blade tip was positioned in vallecula, on each displacement manoeuvre, the epiglottis tended to move into glottic-opening. Further, lifting epiglottis with the blade tip positioned beyond the vallecula threatened to abrade the arytenoid mucosa. TTI-aided tracheal intubation was deemed appropriate to overcome the difficulty. This time, the effort was made to lift the epiglottis with the blade tip placed in vallecula and ELM was exercised to move the glottic-opening to the right of lateral epiglottic margin. An Eschmann™ multiple-use introducer was tried, but it failed to pass through the visible slit-like glottis opening for its soft-tip got folded on itself each time it contacted the glottic-opening. A 'modified' Eschmann multiple-use introducer (body strengthened until the base of the angled tip)[4] passed the cords but could not be advanced further inside the trachea. Finally, a 'new' Portex™ introducer with a lower angled-tip front width passed the cord and moved freely inside the trachea. Tracheal tube (6.5-mm ID) railroading was uneventful.

DISCUSSION

It is not uncommon to use TTI in unanticipated difficult airway situations when difficult-to-displace epiglottis obstructs the view to glottic-opening.[156] Furthermore, it is desirable for a TTI be placed at least up to mid-trachea lest it may come out during tracheal tube railroading. TTIs are generally categorised and selected based on flexibility (rigid/soft), tip's shape (straight/angled), and/or whether a ventilating conduit is present or not (ventilating bougie).[7] The ventral angle at the tip is added to facilitate its entry into the anteriorly placed cords. However, the TTI tip length beyond the bend (point of angulation) to create a ventral angle is not uniform across the available variants [Figure 1a, b and Table 1]. This results in a difference in the width of the front created by the presence of an angled tip. Therefore, approximating tracheal diameter viz-a-viz TTI's angled-tip front width makes it difficult to move freely inside the trachea, more so if the tip catches tracheal mucosa after glottis entry. Presumably, greater the angled-tip front width, more difficult is to move it inside the trachea.

Figure 1

(a) Tracheal tube introducer angled tip deconstruction. (b) Angled-tip front of three commonly used bougies

Table 1

Front-tip profiles of different tracheal tube introducers

Critical extrapolation of technical performance of the different TTIs in the mentioned cases with unanticipated difficult airway due to the presence of difficult-to-move epiglottis revealed intricate differences in TTI's angled-tip front width to be the main problem. While an Eschmann multiple-use introducer and its modification failed to transmit enough user force to the tip to enter the glottic-opening, the unfavourable wide angled-tip front width of rigid blue TTI prevented it to move freely inside the trachea, especially when introduced at an angle 'lateral' to the epiglottis margin. It is also likely that intratracheal advancement of the TTI inserted lateral to the epiglottis at an angle could have been limited by unyielding cartilaginous rings that strengthen lateral tracheal wall and the tracheal mucosa.[8] In general, even with tracheal diameter versus angle-tip front width mismatch, the TTI poses no problem when introduced along the median plane formed by aligned oro-pharyngo-laryngeal airway axes because dorsally deficient tracheal rings desists impediment. Therefore, glottic entry notwithstanding, TTI's intra-tracheal advancement appears to get majorly influenced by: A) the TTI angled-tip front width relative to tracheal diameter, and b) the plane of glottic entry. In either case, since the epiglottis impeded the view to the glottic-opening, we had left only 'lateral approach' for TTI entry. Hence, controlling the TTI angled tip front width was the only option to exercise. In the first case, probably, the Eschmann multiple-use introducer™ failed to enter the glottic-opening as the approximated (due to forceful ELM to bring it rightwards) cords negated the force TTI tip could generate. Thereafter, the first rigid blue TTI that easily entered trachea, failed to advance further. Probably, the actionable angled-tip front width of TTI was wider than patient's intratracheal diameter Figure 1. Ultimately, on the spot analysis prompted us to use another rigid-TTI (the 'new' Portex introducer) with tip having the right mix, i.e., a lesser width angled-tip front and adequate rigidity to follow operator movement.

In the second case, both the 'standard' and the 'modified' Eschmann multiple-use introducer™ with soft atraumatic angled-tip failed to return the favourable result. Again, the successful glottic entry and free intratracheal advancement of a Portex introducer with lower angled-tip front width reinforced the relevance of TTI tip's structural make up.

In unanticipated difficult airway situations purely due to epiglottis dimension and/or mobility issues impeding the view to glottis opening,[9] facilitation of tracheal intubation with conventional manoeuvres (e.g., ELM/BURP, head-extension adjustments) can be effectively complemented by a TTI only if its angled-tip front profile (width, angle) is carefully selected. Furthermore, on-the-spot assessment and selection of the appropriate TTI in terms of its tip-front characteristics would facilitate airway access and secure patient safety.

The difficulty in moving the epiglottis out of the view to visualise glottis entry adequately could have been facilitated by laryngoscope variants specifically designed for epiglottis displacement, i.e., McCoy laryngoscope in the first case and Miller blade in the second case. However, none were available to us. Further, not deciding to go for advanced optic based airway gadgets (CMAC laryngoscopy, fibreoptic system) first-up may be considered a limitation when faced with a difficult-to-access airway due to issues with epiglottis, such as large-sized epiglottis or inability-to-mobilise epiglottis, obscuring the view to the glottis opening.

CONCLUSION

Unanticipated difficult airway situation due to epiglottis dimension and/or mobility issues impairing view to glottis opening requires diligent on-the-spot decision-making and technical expertise for successful airway access and patient's safety. In this regard, tracheal intubation with conventional manoeuvres (e.g., ELM/BURP, head-extension adjustments) can be effectively complemented by a TTI only if its angled-tip front profile (width, angle) is carefully selected from among the types of TTI units available.

Financial support and sponsorship

Financial Support: Purely Departmental.

Conflicts of interest

There are no conflicts of interest.