Truview PCD-video laryngoscope aided nasotracheal intubation in case series of orofacial malignancy with limited mouth opening.

To the Editor,

Unfortunately, very few equipments can be used in patients with reduced interincisor distance (IID) for definitive airway by nasal route. Truview a video laryngoscope (VL) having an optical lens system, produces better glottic view than Macintosh laryngoscope during oral endotracheal tube (ETT) insertion especially when LMA insertion is impossible if IID <20 mm.[123] However, the role of Truview in nasotracheal intubation (NTI) is less reported, and awake flexible bronchoscopy is the gold standard method.[45] Noncooperation of patient, inability to use smaller size tube, precludes the use of bronchoscopy for NTI. Hence, we hypothesized improved Cormack Lehane (CL) grade of glottic view with Truview PCD (Truphatek International Ltd., Netanya, Israel) facilitates NTI and aimed to evaluate its feasibility as an alternative to awake fiberoptic bronchoscopy for elective oncosurgery.

Case 1 [Table 1] lesion in left retromolar trigone, posted for a left commando with Pectoralis major myocutaneous flap (PMMC) flap. On airway assessment IID was 15 mm with Mallampati class IV [Figure 1a]. Thyromental distance was 6 cm, atlantoaxial mobility was adequate. Written informed risk consent obtained and patient fasted 8 h prior to the surgery. Preparation in the form of a difficult airway cart which included minicricothyrotomy, tracheostomy kit and facility for fiberoptic bronchoscope in addition to other equipments was kept ready. Monitoring was instituted with electrocardiogram, noninvasive blood pressure, pulse oximetry, capnography, and temperature. Premedication with injection glycopyrrolate 0.2 mg, injection ranitidine 50 mg, injection metoclopramide 10 mg intravenous (IV) was administered. Nasal decongestion was achieved with 2 drops of 0.05% xylometazoline and lubricated with 2% lignocaine jelly to facilitate NTI. Following preoxygenation for 3 min anesthesia was induced with 100% O2 in sevoflurane in increasing concentration up to 8% until the abolition of eyelash reflex on spontaneous respiration. After ensuring mask ventilation injection succinylcholine 1 mg/kg IV was administered. A preformed well-lubricated 8.0 mm cuffed North Pole ETT was advanced gently through the right (Rt) nostril in the oropharynx. Truview PCD scope was attached to an oxygen flow of 6 L/min to avoid fogging, advanced into the oral cavity until larynx was visualized [Figure 1b]. As glottic view of CL Grade IIa obtained, tip of the nasotracheal tube was gently maneuvered and advanced under vision into the trachea [Figure 1c and d]. ETT position was confirmed by chest auscultation and capnography and the time for intubation was 40 s. Anesthesia was maintained with 50: 50 O2 in N2O with sevoflurane and nondepolarizing muscle relaxant injection vecuronium 4 mg IV and top up dose of 1 mg as required. Injection butorphanol 2 mg IV was administered for analgesia. Hemodynamic parameters were monitored throughout the procedure [Table 1]. At the end of surgery neuromuscular blockade was reversed after attempts at spontaneous respiration with injection glycopyrrolate 0.5 mg and injection neostigmine 2.5 mg. ETT kept in situ on T-piece, under sedation with midazolam/fentanyl infusion and extubated 24 h later when all the extubation criteria were fulfilled.

Table 1

Airway parameters and hemodynamic change during tracheal intubation

Figure 1

Patient 1 - (a) Interincisor distance 15 mm. (b) Nasal insertion of 8 mm North Pole tube with Truview in situ. (c) Tip of endotracheal tube being negotiated through vocal cords. (d) Nasotracheal intubation with Truview

Case 2 [Table 1] (Rt lower alveolus lesion) and Case 4 (Ca cheek) for surgery had successful NTI with North Pole tube. The same protocol was followed as per the previous case.

Case 3 [Table 1] (Ca cheek) and Case 5 (operated Rt commando with forehead flap with recurrence of lesion at the left angle of mouth Figure 2a and d) had an unsuccessful NTI using North Pole ETT. Ventilating bougie (15.0 Ch, 5.00 mm) aided NTI (Rusch flexometallic ETT) was performed with Truview in Patient 5 [Figure 2b and c].

Figure 2

Patient 5 - (a) Interincisor distance 20 mm. (b) Truview guided picture of insertion of bougie through vocal cords. (c) Bougie guided nasotracheal intubation (NTI). (d) NTI

One of the important factors of airway assessment is IID. The average IID is 3.5-4.5 cm.[3] Adequate mouth opening is essential for Macintosh laryngoscopic blade but has limited role if mouth opening is <25 mm. Traditionally, awake fiberoptic NTI is the airway management of choice in these patients.[4] Caterina Finizia has found incidence of trismus of <3.5 cm in 9% of in patients with head-neck cancer which is non-negligible.[5] All our patients had Grade II trismus (IID of 25-10 mm) as per Becker's grading[6] due to surgical pathology or radiotherapy.

A study by Blair et al. on VL found improved glottic exposure as compared with direct laryngoscopy (97%CL Grade I or II vs. 51%, P < 0.01) in difficult airway scenarios using medium fidelity human simulators.[7] Singh et al. studied Truview and noted CL Grade of I-III in 46 (92%) patients of difficult airway. However, some external manipulation was required during the negotiation of ETT, but reported no significant difference in intubation time.[2]

A manikin study by Sanchez et al. concluded that VL could be a good option when performing NTI with a restricted mouth opening using McGrath, C-Mac and Truview with IID of 3.5, 3.0, 2.5, 2.0, and 1.5 cm.[8] Raveendra et al. evaluated Truview laryngoscope for NTI in 50 patients of American Society of Anesthesiologists Grade I/II undergoing orthognathic procedures. CL Grade I view in 86% cases and 94% patients had successful NTI and intubations time <43 s in 50% cases.[9] However, patients with difficult airway were excluded from the study and still no published data reported for use of Truview for NTI in difficult airway. In our cases of limited mouth opening an improved CL Grades II-III view obtained without much prolonged intubation time as observed in above studies.[2789]

In human, air conduction is easily facilitated through nares to trachea, but during NTI with direct laryngoscopy trachea moves anteriorly, distorting normal anatomy, so lifting of tip of the tube with Magill's forceps is required, which may lead to trauma/bleeding and prolongs the intubation time. With use of nonline-of-sight view VL less anterior force is needed and anatomical alignment of the airway is preserved and thus may facilitate nasal intubation.[10] This also explains less need of preshaped ETT/use of stylet or ETT tip handing during nasal as compared to oral intubation with Truview. The problems like hitting of ETT posterior to arytenoids where some pulling out and rotation over left arytenoids, twisting over epiglottic aperture or external laryngeal pressure and little withdrawal of the blade to lessen tilting of laryngeal axis may be helpful. Familiarity with the equipment minimizes these problems while handling Truview/Glidescopes, etc.[11] The anesthesiologist performing NTI had enough experience of oral intubation with Truview, also encountered difficulty in negotiation of ETT, but managed these using similar measures as above. There was hemodynamic stability and no incidence of airway trauma in our patients. Puchner et al. also reported less difficulty score with Airtraq [Pradol Meditec SA] and Glidescope [Bothell, WA, USA] than with the Macintosh laryngoscope.[12]

We successfully used Truview for NTI even when IID was less.

The improved glottic view permits more maneuvers to facilitate NTI than the oral route. However, familiarity with the device is essential before we use it in difficult airway scenarios.