Fiberoptic Bronchoscope Guided Assessment of Vocal Cord Function Using Bailey's Manoeuvre With an I‐Gel Supraglottic Airway Device in Patients Undergoing Thyroid Surgery: An Initial Exploratory Prospective Study

Vocal cord paralysis secondary to the injury of the recurrent laryngeal nerve (RLN) leading to postoperative hoarseness of voice, laryngeal aspiration, and life-threatening respiratory distress is one of the most feared complications of thyroid surgery. However, despite meticulous anatomical identification during surgery, RLN palsy is seen in up to 12% of the cases [1]. Early diagnosis of iatrogenic vocal cord injury is crucial before extubation, and guidelines like the American Head and Neck Society consensus emphasise the importance of early laryngeal examination after thyroid surgery [2]. Various methods have been described to perform a thorough examination of vocal cords during and after extubation including direct laryngoscopic or direct fiberoptic-guided visualisation of vocal cord movement [3, 4]. The greatest limitation of the examination is patient tolerance, apprehension and discomfort. Furthermore, caution should be observed in patients with a history of poorly controlled hypertension and cerebrovascular diseases as these techniques are associated with hemodynamic perturbations. Techniques like laryngeal muscle electromyography, and electromyography with orotracheal tube-inserted electrodes are not freely available and are expensive. Radiological examinations like computed tomography (CT), and magnetic resonance imaging (MRI) are not possible before extubation [4, 5]. Transcutaneous laryngeal ultrasound (TLUSG), a non-invasive technique is gaining popularity for early diagnosis of vocal cord palsy before extubation. However, it requires training and is associated with lower reliability and potential interobserver variability [5-7]. The use of fiberoptic to visualise the glottic structures through a supraglottic airway device (SGAD) inserted as a part of the Bailey's manoeuvre before extubation is a novel non-invasive technique of assessing vocal cord function. It also serves the dual purpose of ensuring a smooth extubation which is essential in thyroid surgery [8, 9]. The Bailey's manoeuvre involves the replacement of an endotracheal tube (ETT) with an SGAD to maintain a patent airway at the end of surgery [9-11]. We hypothesised that the insertion of FOB through an SGAD would aid in providing adequate visualisation of the glottis and assessment of vocal cord movement before extubation. Our primary objective was to assess the degree of visualisation of the vocal cords using a fiberoptic bronchoscope (FOB) inserted through the main stem of the SGAD. Our secondary objectives included an assessment of the incidence of vocal cord palsy, the total time taken for insertion of the SGAD and an assessment of vocal cord function. We also assessed the hemodynamics (Heart rate [HR] and mean arterial pressure [MAP]) of the patient, the cough score and the patient reactivity score (PRS) along with the surgeon's satisfaction with the assessment of vocal cords function. This prospective observational study was conducted at a tertiary-level hospital between December 2020 and December 2021. The ethical approval for this study was provided by the institutional ethics committee (INT/IEC/2020/SPL-782, 24/06/2020). It was also registered in the clinical trial registry-India (CTRI) (CTRI/2020/07/026804, 27/07/2020) before patient enrollment and conformed to the standards of the Declaration of Helsinki. Patients aged 18 to 65 years of age, belonging to the American Society of Anesthesiologists (ASA) physical status 1 and 2 undergoing thyroid surgery under general anaesthesia were recruited after obtaining written informed consent. Patients with pre-existing vocal cord palsy and those undergoing emergency surgery were excluded. Patients with a body mass index > 35 kg/m2, the presence of a high risk of aspiration and those having contraindications to SGAD placement were also excluded from the study. A detailed preanaesthetic evaluation was done and a standard institutional protocol was followed for the induction and maintenance of anaesthesia. Inside the operation theatre, ASA standard monitoring was instituted consisting of 5 lead electrocardiogram, non-invasive blood pressure (NIBP) and pulse oximetry. Additional monitors included the bispectral index (BIS) and neuromuscular monitoring. General anaesthesia was induced with intravenous fentanyl (2 mcg/kg), propofol (1.5–2.5 mg/kg) titrated to the loss of verbal response and vecuronium (0.1 mg/kg) was administered to facilitate endotracheal intubation with an appropriately sized flexo metallic ETT after ensuring the train of four (TOF) count was zero. Anaesthesia was maintained with a mixture of oxygen-nitrous oxide (50%–50%) and isoflurane at a minimum alveolar concentration of 0.8–1 titrated to maintain BIS of 40–60. The neuromuscular block was maintained with intermittent doses of vecuronium (0.05 mg/kg) to maintain a TOF count < 2. At the end of the surgery, thorough oral suctioning and preoxygenation with 100% oxygen via the ETT was done while keeping the patient in a deep plane of anaesthesia (BIS 50–60) (Figure 1). After this, the Bailey manoeuvre was performed that is, an I gel SGAD (Intersurgical Ltd., Berkshire, UK) was inserted posterior to the flexo metallic ETT in situ, Figure 2A. The size of I gel SGAD was determined according to the patient's weight (Sizes 2.5, 3, 4 and 5 for 20–30, 30–50, 50–90 and > 90 kgs respectively). After placement of the SGAD, a FOB was inserted through the main stem of the SGAD to confirm the correct placement of SGAD by visualising the vocal cords with ETT in situ, Figure 2B,C. The FOB was kept in situ there for subsequent vocal cord examination. The residual neuromuscular blockade was then reversed with neostigmine 0.5 mg/kg and glycopyrrolate 0.1 mg/kg after attaining the TOF Count 4. Once spontaneous respiration resumed with the patient still under general anaesthesia (BIS 60–70), the ETT cuff was deflated and the ETT was partially removed. The FOB-guided visualisation of glottic structures including the vocal cords through the SGAD was performed during the process of gradual removal of the ETT, Figure 2D–F. If both the vocal cords were found to be bilaterally mobile, the ETT was removed, Figure 2G. The anaesthetic agents were then titrated and stopped and the patients were allowed to wake up following which the SGAD was removed. Patients with unilateral vocal cord palsy were shifted to the ICU and vitals were closely monitored. In the patients with bilateral vocal cord palsy, the ETT was reinserted under fiberoptic guidance and shifted to the ICU for overnight ventilation. After 24–48 h, the severity of vocal cord palsy and the degree of laryngeal oedema were reassessed. A trial of extubation was given if adequate tidal volume was generated. In case of respiratory distress, an early tracheostomy was planned. The grading of vocal cord visualisation was then done using the FOB inserted through the I gel SGAD, with the patient under general anaesthesia (BIS 60–70) while maintaining spontaneous respiration. We used a five-point scale to grade the laryngeal view, Table 1A [12]. The movement of the vocal cords was assessed in both inspiration and expiration. We also noted the incidence of vocal cord palsy (unilateral/bilateral, partial/complete) and the total time taken, starting from the insertion of SGAD till the completion of the vocal cord assessment. The hemodynamics HR and MAP were also noted at T1: baseline (before SGAD insertion); T2: after insertion of the SGAD; T3: during FOB insertion; T4: removal of the ETT; T5: return of spontaneous respiration; T6: at the time of vocal cords assessment; T7: removal of SGAD and T8: on arrival to the post-anaesthesia care unit (PACU). The reaction of the patient during the Bailey's Manoeuvre was recorded using the PRS, Table 1B [13]. The quality of extubation was also assessed using the cough score, Table 1C [14]. The surgeon's satisfaction with the assessment of vocal cord function was graded using a Likert's scale (0: not satisfied, 1: satisfied and 2: very much satisfied) along with any complications during the Baileys manoeuvre and 24 h postoperatively [15]. The statistical analysis was carried out using Statistical Package for Social Sciences (IBM SPSS Inc., Chicago, IL, version 22). The normality of the data were checked by using the Shapiro–Wilk test. Data were presented as mean ± SD when normally distributed and as median (interquartile ranges) in case of non-normal distribution. Categorical data were expressed as count (%). Intra-group analysis of hemodynamic data were carried out using the student-paired t-test. Two-tailed p < 0.05 was considered statistically significant with a 95% confidence interval. Since this was an exploratory study no formal sample size was calculated. Sixty-five patients were assessed for inclusion in the study and 50 patients met the inclusion criteria. The baseline demographic profile was similar with the mean age of the patients being 36 years and a majority of patients being female (86%). The most common comorbidity was hypertension (62%) and multinodular goitre was the most common pathology seen in 66% of the patients followed by colloid goitre seen in 24% of the patients. A complete view of the glottic anatomy was visualised in 76% of the patients while a Grade 2 view of the glottic anatomy was seen in 20% of the patients. Grade 3 view was seen in 2 patients while the Grade 4/5 view of the glottis was not observed in any patient. Partial unilateral vocal cord palsy was seen in 3 patients, while one patient had complete unilateral vocal cord palsy. Partial bilateral vocal cord palsy was seen in 2 patients. Complete bilateral vocal cord palsy was not seen in any patient. The total time taken for the insertion of SGAD and fiberoptic-guided assessment of vocal cord function was 126.46 ± 21.5 s. The patient tolerated the procedure well with Grade 1 PRS observed in 76% of the patients and Grade 2 seen in 18% of the patients. Two patients had a PRS of Grade 3 while a Grade 4 PRS was seen in one patient. There was a significant increase in HR and MAP (p = 0.001) on insertion of the SGAD as compared to the baseline, Supplementary digital content-2. It was however not clinically significant and within normal limits. The quality was extubation was also smooth with a cough score of Grade 0 (no cough) seen in 64% of the patients and a mild cough seen in 32% of the patients. The surgeon was also satisfied with a surgeon satisfaction score of Grade 2 in 78% of the surgeries, Table 2. There were no complications seen with Bailey's manoeuvre. We found that SGAD-guided flexible bronchoscopic evaluation of vocal cord function in patients undergoing thyroid surgery led to adequate visualisation of the glottic anatomy that is, epiglottis, the entire length of the vocal cords and arytenoid cartilages (Grade 1) in 76% of the patients within 1–2 min (126.46 ± 21.5 s). Akin to our study, Tan et al. reported three cases where the laryngeal mask airway (LMA) protector was used in conjunction with the Bailey's manoeuvre for flexible bronchoscopic guided assessment of vocal cords mobility. They reported successful placement of the SGAD on the first attempt and obtained Brimacombe Grade 2 (vocal cords and anterior epiglottis seen) or Grade 3 (vocal cords and posterior epiglottis seen) equivalent fibre-optic laryngeal view [16]. The Brimacombe scoring system was used primarily to evaluate the correct position of the LMA. Whereas, we used a scale proposed by Arevalo et al. based specifically on the degree of fiberoptic-guided visualisation of glottic structures through the I-gel SGAD which was our primary objective. This scale also has the potential to anticipate the ease of performing endotracheal intubation through the device [17]. Various techniques have been studied for the assessment of vocal cords function including direct laryngoscopy performed immediately post-extubation, Table 3. However, a recent study reported that 92.1% of patients with Grade 1 Cormack and Lehane view during intubation worsened to Grade 2 (76.3%) and Grade 3 (15.8%) during extubation and a few patients did not permit direct laryngoscopy. A significant increase in HR and MAP lasting up to 5 min after the procedure along with a higher degree of patient discomfort (median PRS 3, range 1–3) was also seen [18]. The use of a small-diameter fiberoptic scope inserted intranasally for the assessment of vocal cord mobility was found to be comfortable for patients emerging from anaesthesia with a PRS of 2 [18]. This technique however requires operator expertise, adequate topical nasal anaesthesia, longer time and patient cooperation which might be difficult during emergence. We assessed vocal cord function when the patient was under an adequate depth of anaesthesia (BIS = 60–70) while maintaining spontaneous respiration and found that most of the patients (76%) tolerated the procedure well with a PRS score of 1 (no facial grimace). Video laryngoscopes like the Airtraq have been found to be better than the conventional Macintosh laryngoscope in terms of the optimal glottic view obtained and less force required [19]. However, the introduction of a video laryngoscope requires a deeper plane of anaesthesia and extubation of these patients in deeper planes predisposes them to complications like breath-holding, laryngospasm, aspiration and airway collapse. TLUSG has also recently emerged as an alternative to assess vocal cord function before extubation. However, studies have found varying rates of sensitivity (64%–85%) of TLUSG limiting its utility, especially in elderly male patients with calcification and acute angle of the thyroid cartilage [20]. Moreover, high failure rates of up to 20% have been reported with TLUSG along with a longer procedural time of 2–8 mins [21]. Lacoste et al. compared the ease of visualisation and detection of vocal cord palsy post-extubation and found that direct and indirect laryngoscopies were only effective in 76% and 73%, respectively, of the patients, whereas flexible laryngoscopy was effective in 99.6% of them. Hemodynamic variations were also significantly lower with flexible and indirect laryngoscopies than with direct laryngoscopy [22]. Bronchoscopic assessment through the SGAD can also be used to diagnose supraglottic swelling, extraglottic collapse on inspiration and intrathoracic collapse on expiration in high-risk patients after thyroid surgery [23]. The SGAD additionally has a ‘stenting’ effect on the upper airway, which is known to be at risk of collapsibility and moreover, an ETT can also be railroaded over the flexible bronchoscope to secure the airway through the SGAD. The shape of the LMA automatically guided the fiberscope towards the vocal cords. Intubation using the SGAD for the insertion of the ETT and subsequently retaining it in place during surgery reduces airway manipulation and might provide additional protection against potential (micro)-aspiration during surgery [24]. We observed a transient increase in HR and MAP on insertion of the SGAD during Bailey's manoeuvre which wasn't clinically significant and was within normal limits. We found that the quality was extubation was smooth with a cough score of Grade 0 (no cough) seen in 64% of the patients. Bailey's manoeuvre decreases the occurrence of transient hypertension, tachycardia and bucking associated with extubation which can potentially lead to post-thyroidectomy bleed or hematoma formation in the neck [9-11]. It can also be used to reintroduce the ETT if necessary. In addition, the FOB can be used to differentiate between vocal cord paralysis and other causes of hoarseness such as vocal cord polyps or arytenoid dislocation. Moreover, it is possible to make a recording as well for future reference. This preliminary exploratory study has several limitations, the foremost being a small sample size. We used the I-Gel SGAD which lacks the features of third-generation SGADs. Newer SGADs like vision-incorporated video LMAs are available which have videoscopes whose distal end is able to move in a range of 140° incorporated into the body thus facilitating a complete view of the glottis and accurate assessment of vocal cord function. It is also necessary to compare this technique with other non-invasive, convenient accurate methods of assessment of vocal cord function like TLUS. The Bailey's manoeuvre cannot be recommended as a safe extubation strategy whenever a difficult airway is encountered in the case of subglottic pathology. Additionally, insertion of FOB in some SGADs requires interruption of ventilation. Further studies with a larger sample size comparing this technique with other methods of vocal cord assessment are necessary to establish the sensitivity and specificity of SGAD-guided bronchoscopic vocal cord assessment. Visualisation of glottic structures using a FOB with SGAD assistance is easily achieved, as evidenced by the optimal laryngeal view obtained within 1–2 min. This technique emerges as a promising alternative for assessing vocal cord function post-thyroidectomy. Additionally, the procedure demonstrates minimal patient discomfort, ensuring stable hemodynamics and a smooth extubation process. To definitively establish the utility of SGADs in thyroid surgery, further multicentre studies involving SGADs capable of ETT insertion and securing the airway are necessary. Ashwini Reddy was involved in study methodology, investigation, draft manuscript preparation, review and editing. Nidhi Singh was involved in, investigation, supervision, data analysis, draft manuscript preparation, review and editing. Narender Kaloria was involved in study conception and design, data collection, investigation, supervision, visualisation, review and editing along with the critical revision of the manuscript for important intellectual content. Shiv Lal Soni was involved in study conception and design, data collection, supervision, draft manuscript preparation, review and editing. Ajay Singh was involved in study conception and methodology, resources, investigation, visualisation, supervision, analysis of data, review and editing along with the critical revision of the manuscript for important intellectual content. Naveen Banavathu Naik was involved in study conception and methodology, resources, visualisation, data analysis, review and editing along with the critical revision of the manuscript for important intellectual content. Naresh Panda was involved in data collection, investigation, supervision, visualisation, draft manuscript preparation, review and editing. All authors reviewed the results and approved the final version of the manuscript. This manuscript has been read and approved by all the authors, the requirements for authorship as stated earlier in this document have been met, and each author believes that the manuscript represents honest work if that information is not provided in another form. The ethical approval for this study was provided by the institutional ethics committee (INT/IEC/2020/SPL-782, 24/06/2020). The authors declare no conflicts of interest. Data will be shared by the authors on request. The peer review history for this article is available at https://www.webofscience.com/api/gateway/wos/peer-review/10.1111/coa.14227.