|Year : 2019 | Volume
| Issue : 1 | Page : 17-21
Is neck roentgenogram essential for airway assessment in thyroid swelling? A 3-year audit in a tertiary care centre
Radhakrishna Shetty Sumalatha, Balaram Chandana, Kandavar Siri
Department of Anaesthesiology, K S Hegde Medical Academy, Mangalore, Karnataka, India
|Date of Web Publication||25-Apr-2019|
Dr. Balaram Chandana
#28, 2nd Main, Amarjyothi Layout, Anand Nagar, R T Nagar Post, Bengaluru - 560 032, Karnataka
Source of Support: None, Conflict of Interest: None
Introduction: Thyroid swelling leading to airway compromise offers a challenge to the anaesthesiologist. Neck roentgenograms are routinely done as a part of preanaesthetic evaluation in thyroid swellings in our institute. With this audit, we wished to analyse whether routine neck roentgenograms had any role in the airway assessment and management for thyroidectomy. Methodology: After obtaining clearance from the Institutional Ethics Committee, data of all patients who underwent thyroidectomy under general anaesthesia between January 2015 and December 2017 were collected from the Medical Records Department. We collected demographic details along with the details of anaesthetic management of these patients. Our primary objective was to know whether neck roentgenogram was essential in thyroidectomy, and the secondary objective was to analyse the airway management in these patients. Qualitative data were represented as frequencies and percentages and quantitative data as mean and standard deviation. Chi-square test was used to compare the qualitative variables and t-test for quantitative variables, and P < 0.05 was considered statistically significant. Results: A total of 317 thyroidectomies were conducted in our hospital between January 2015 and December 2017. Neck X-ray was done in 275 patients (86.75%), whereas the X-ray was not found or documented in 15 patients (5.45%). X-rays of only 42 patients (16.15%) had positive findings. In 66.7% of the cases with positive finding on neck X-ray, airway was managed with direct laryngoscopy and intubation without any difficulty. Conclusion: We conclude that neck roentgenographs are not a sensitive method for predicting difficult airway in patients with thyroid swelling and could be avoided in routine practice to decrease radiation exposure.
Keywords: Difficult airway prediction, goitre, neck roentgenograph, thyroidectomy
|How to cite this article:|
Sumalatha RS, Chandana B, Siri K. Is neck roentgenogram essential for airway assessment in thyroid swelling? A 3-year audit in a tertiary care centre. Airway 2019;2:17-21
|How to cite this URL:|
Sumalatha RS, Chandana B, Siri K. Is neck roentgenogram essential for airway assessment in thyroid swelling? A 3-year audit in a tertiary care centre. Airway [serial online] 2019 [cited 2019 Dec 11];2:17-21. Available from: http://www.arwy.org/text.asp?2019/2/1/17/257051
| Introduction|| |
Thyroid swelling leading to airway compromise often poses a challenge to the anaesthesiologist. Difficult intubation (DI) in surgical patients undergoing thyroidectomy under general anaesthesia is estimated at 1.5%–13%., Thyroid swellings are associated with a distorted airway due to tracheal deviation, compression or both, making intubation and rigid laryngoscopy difficult. These patients need a thorough clinical airway examination and a meticulously planned airway management strategy to prevent catastrophic adverse effects. Various techniques have been developed to assess airway compromise in patients with thyroid swelling. Although neck roentgenogram is the most common method, its efficacy in predicting a difficult airway is at times doubtful.,, Preoperative risk factors such as a large goitre or a long-standing goitre are commonly associated with tracheal narrowing and/or deviation. Many years down the line, we still cannot claim with certainty that a particular method of preoperative evaluation of the airway has the highest predictive value in assessing the possibility of DI because there are not enough well-documented studies addressing this issue.
In our institute, anteroposterior and lateral neck roentgenographs are routinely performed in all patients undergoing thyroid surgeries, which might expose patients to unnecessary radiation besides the additional expenditure to the patient. We conducted this study with the hypothesis that anteroposterior and lateral neck roentgenograms advised for all thyroid swellings cannot definitely predict a difficult airway and can be excluded in certain cases. We aimed to find out if these roentgenographs had any role in predicting difficulty in endotracheal intubation.
| Methodology|| |
A retrospective observational study was conducted in a tertiary care hospital in January 2019 after obtaining Institutional Ethics Committee clearance. The study population included patients who underwent thyroid surgery from January 2015 to December 2017. Patient records were obtained from the medical records department, and the study did not involve any patient interaction or intervention. As we did not include any information that would have disclosed the identity of the patient, we did not seek patient consent. Statistical analysis was performed by SPSS software (Version 17.0, SPSS Inc., Chicago, IL, USA). It was considered statistically significant (all two-tailed) with P < 0.05. Qualitative data were represented as frequencies and percentages and quantitative data as mean and standard deviation (SD). Chi-square test was used to compare the qualitative variables and t-test for quantitative variables, and P < 0.05 was considered statistically significant.
We included patients in whom thyroid surgery was performed under general anaesthesia with endotracheal intubation between January 2015 and December 2017. Patients in whom documentation was inadequate or instances where records were missing were excluded from the study. Demographic variables such as age and gender were noted while maintaining patient anonymity. Compressive symptoms such as breathlessness, dysphagia and/or change of voice at presentation and duration of swelling were noted. Anteroposterior and lateral neck roentgenographs of these patients were assessed by an anaesthesiologist with a training of 2 years or more for evaluating tracheal deviation, compression or both. From the anaesthesia records, we documented the intubation and extubation details of those cases. Other details regarding airway examination, Mallampati classification, the technique used for airway management, Cormack–Lehane grading, muscle relaxant used for intubation and mobility of vocal cords before surgery were also noted.
| Results|| |
Our records revealed that 317 cases were operated for thyroid surgery in the 3-year period of the study. We found that thyroidectomy was more commonly performed in females (86.1%) [Figure 1]. The mean age (±SD) of the patients was 45 ± 11.8 years. The youngest patient operated was 17 years, whereas the oldest was 80 years. It was found that of the 317 cases that were operated, 167 were for multinodular goitre. The duration of swelling at presentation ranged from 1 month to 36 years (mean: 50.35 ± 64.7 months). The size of thyroid lesions ranged from 1.0 to 17.0 cm [Table 1].
We noted that of 317 patients, 58 (18.296%) patients had compressive symptoms such as cough, difficulty in breathing, dysphagia and change in voice at presentation. The most common presenting complaint was change in voice (6.94%), followed by dysphagia (5.99%) and difficulty in breathing (3.47%) [Table 2].
Preoperative anteroposterior and lateral neck X-rays were obtained for assessment of tracheal compression or deviation in 275 cases (86.75%) [Figure 2]. X-ray neck was not done in 42 (13.25%) cases prior to surgery. We found that 1 of these 42 cases had a preoperative computed tomography scan which showed compression of the trachea, and this patient was managed with fibreoptic intubation. One case posted for thyroglossal cyst excision had been included under thyroid surgery in our records. Forty-two cases in whom X-ray was not done were managed intraoperatively with direct laryngoscopy (DL) and intubated in the conventional way after induction and muscle relaxation. Here, the difficulty in intubation was assessed based on the clinical examination findings of mouth opening, neck movements, Mallampati class, thyromental distance and temporomandibular joint mobility. Of the 275 patients in whom neck roentgenographs were ordered preoperatively, neck X-ray was missing in 15 patients, and hence, we could not assess the trachea radiologically in these 15 patients. We assessed 260 X-rays and found that 218 (83.85%) X-rays were normal. Forty-two (16.15%) patients had positive X-ray finding suggesting a possible difficult airway.
In patients who had a normal finding in neck X-ray (218), 189 (86.7%) were managed with conventional DL and intubation. In 24 patients (11%), succinylcholine was used to achieve muscle relaxation because difficult airway was suspected by the clinical findings. Four patients had to be managed with fibreoptic intubation as clinical predictors of difficult airway such as a large thyroid swelling with restricted neck movements were present even though the X-ray showed no positive findings. One case was intubated using a videolaryngoscope. Of 15 patients where X-ray was not documented, 10 were intubated with DL, 4 using succinylcholine and 1 with fibreoptic scope [Table 3].
We found that larger swellings (vertical dimension: 10 ± 1.15 cm and horizontal dimension: 7.5 ± 0.7 cm) had positive findings on neck X-ray. There was a correlation between the duration of swelling and X-ray findings as well as swellings of longer duration presenting with positive findings. It was observed that 5 of 11 patients who had difficulty in breathing and 7 of 19 cases with dysphagia had positive X-ray findings. Modified Mallampati class was 1 or 2 even in patients with positive X-ray findings.
| Discussion|| |
The term 'airway' refers to the upper airway which is defined as the extrapulmonary air passage, consisting of the nasal and oral cavities, pharynx, larynx, trachea and bronchi. Difficult airway implies a problem in maintaining gas exchange through a face mask, an artificial airway or both. Identifying a difficult airway allows time for preparation, correct selection of equipment and techniques and management in a meticulous way. Classical findings in a patient that suggest a difficult airway are, to name a few, poor flexion or extension of the head on the neck, receding mandible and presence of prominent teeth, reduced atlanto-occipital distance, a reduced space between C1 and the occiput and a large-sized tongue. The Mallampati classification that is most commonly used correlates the size of the tongue relative to the pharyngeal size.,
This study was planned to analyse the ability of neck X-ray in predicting DI prior to thyroidectomy. We observed that neck X-ray could be avoided in most of these patients unless really indicated. Enlargement of the thyroid gland can be associated with DI due to tracheal deviation, compression or both [Figure 3] and [Figure 4]. DI was defined as 'tracheal intubation without visualisation of the glottis during laryngoscopy' (Grade III or IV according to Cormack–Lehane laryngoscopic grade).
|Figure 3: Lateral X-ray neck in a patient with prolonged thyroid swelling showing compression of trachea|
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In our study of 317 patients, 42 were identified to have DI (by virtue of X-ray findings). Conventional DL and intubation were possible in 65.62% of cases with deviation of trachea (21/32 patients) and 50% of cases with tracheal compression and deviation (2/4 patients) on X-ray. Fibreoptic/flexible scope was used in 2.3% (6/260) of cases with long-standing thyroid swelling ± restricted neck movements.
A study by Kalezić et al. that included a large number of patients who underwent thyroidectomy concluded that the strongest predictors of DI were history of previous DI, thyroid gland disease, size of the neck (circumference and length), receding (retrognathic) mandible, teeth (irregular, large) and oral anomalies (small mouth, macroglossia).
The World Health Organisation has classified goitre according to the size: Class 0 – palpable mass within neck structure; Class I – visible, palpable and undermines the curves and the neck line; and Class II – a very large goitre with retrosternal extension that causes tracheal deviation, compression of the trachea and oesophagus.,
Studies have shown that <5% of patients undergoing thyroidectomy have tracheal compression. Majority of the patients are managed with intravenous induction and intubation under muscle relaxant. Although thyroid swellings may be very big causing dramatic degrees of tracheal compression, they need not necessarily compromise the airway and can be managed tactfully by an experienced anaesthesiologist.,, A combination of several investigations is necessary along with a high index of suspicion to predict DI.
| Conclusion|| |
This study indicates that neck roentgenogram is not needed in all cases with thyroid swelling for predicting DI. Specific thyroid conditions such as a large thyroid, long-standing thyroid swellings and retrosternal extension of the thyroid require neck X-ray (anteroposterior and lateral views) to plan airway management.
If neck X-ray is used in indicated cases only, one can not only ensure effective use of workforce and resources but also prevent unnecessary exposure to radiation and avoidable additional expenses for patients.
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Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4]
[Table 1], [Table 2], [Table 3]