|Year : 2021 | Volume
| Issue : 2 | Page : 85-89
Evaluation of difficult airway in trauma patients from lateral cervical radiographs
Aysenur Gultekin1, Mustafa Korkut2, Secgin Soyuncu3, Cihan Bedel2
1 Department of Emergency Medicine, Ataturk State Hospital, Antalya, Turkey
2 Department of Emergency Medicine, Antalya Training and Research Hospital, Health Science University, Antalya, Turkey
3 Department of Emergency Medicine, Faculty of Medicine, Akdeniz University, Antalya, Turkey
|Date of Submission||05-Apr-2021|
|Date of Acceptance||12-May-2021|
|Date of Web Publication||10-Aug-2021|
Dr. Cihan Bedel
Department of Emergency Medicine, Antalya Training and Research Hospital, Health Science University, Kazım Karabekir Street, Postal Zip Code: 07100, Muratpaşa, Antalya
Source of Support: None, Conflict of Interest: None
Background: Many tests have been developed that are used either singly or in combination to identify a difficult airway. However, airway patency may not be adequately evaluated in some patients despite these tests. Lateral cervical radiography can be an auxiliary technique to evaluate difficult airway in patients of trauma due to its bedside applicability, cost-efficiency and rapidity. The aim of this study was to investigate the usefulness of lateral cervical radiographic measurements in predicting difficult laryngoscopy in trauma patients. Patients and Methods: The study consisted of patients of trauma who were admitted to the emergency department between July 2017 and March 2018. All patients underwent bedside cervical radiography and seven measurements were obtained. The anterior and posterior mandibular depths, effective mandibular length, atlanto-occipital distance, mandibulohyoid distance, thyromental distance and distance between the superior temporomandibular joint and the inferior edge of the fourth cervical vertebra (C4) were measured on the radiographs. Patients were divided into two groups as difficult and easy laryngoscopy groups, and the parameters were compared between the groups. Results: A total of 97 patients were included in our study. Of these patients, 54 (55.6%) were in the difficult laryngoscopy group, while 43 (44.4%) were in the easy laryngoscopy group. The interincisor, hyomental and thyrohyoid distances were significantly lower in the difficult laryngoscopy group compared to the easy laryngoscopy group. Conclusion: Bedside lateral cervical radiography is not a useful imaging method to demonstrate difficulty in laryngoscopy in patients of trauma.
Keywords: Difficult laryngoscopy, emergency, lateral cervical radiography, Mallampati class
|How to cite this article:|
Gultekin A, Korkut M, Soyuncu S, Bedel C. Evaluation of difficult airway in trauma patients from lateral cervical radiographs. Airway 2021;4:85-9
|How to cite this URL:|
Gultekin A, Korkut M, Soyuncu S, Bedel C. Evaluation of difficult airway in trauma patients from lateral cervical radiographs. Airway [serial online] 2021 [cited 2022 Jan 27];4:85-9. Available from: https://www.arwy.org/text.asp?2021/4/2/85/323568
| Introduction|| |
Emergency airway management poses many challenges. The emergency patient population generally consists of patients with an unsuitable fasting period and an inability to receive appropriate premedication. Approximately 1%–3% of tracheal intubation cannot be achieved by standard methods. Difficult mask ventilation is defined as the failure to keep oxygen saturation above 90%, despite the optimal position and use of airway adjuncts for airway management. Three-failed intubation attempts by an experienced practitioner or inability to provide oxygenation is termed a “failed airway.”,
Presence of beard, obesity, short neck, a small or large jaw, rabbit tooth, high-arched palate and any airway deformity related to trauma, tumour or inflammation are physical findings associated with difficult intubation. Many tests have been developed that can be used alone or in combination to identify a difficult airway. However, airway patency may not be adequately evaluated in some patients despite these tests. Patient history, a medical condition related to the airway and mouth opening, and jaw and neck movements may help detect a difficult airway. The Mallampati classification and LEMON score are the most common clinical tests used to evaluate a difficult airway., Radiological measurements can also be used to evaluate a difficult airway. While clinical classifications can be used in medical patients admitted to the emergency department, their use may be insufficient in evaluating difficult airway in trauma patients with limited cervical mobility, those who need a cervical collar and those who cannot be positioned for performing the Mallampati test. Lateral cervical radiography can be an auxiliary technique to evaluate difficult airway in trauma patients due to its bedside applicability, cost-efficiency and rapidity. The aim of this study was to investigate the effectiveness of lateral cervical radiographic measurements in predicting difficult airway in trauma patients by comparing these measurements with clinical measurements performed for the evaluation of difficult airway.
| Patients and Methods|| |
Our study was designed as a prospective cross-sectional study. The study consisted of patients who were admitted to the emergency department of a tertiary care university hospital due to trauma between July 2017 and March 2018. Written informed consent was obtained from all patients before participating in the study. Our study consisted of adult patients (≥18 years of age). Those with airway abnormalities (facial and/or neck wounds, unstable cervical spine and history of cervical spine fixation), those not undergoing measurement due to emergency conditions or with incomplete data and those refusing to participate were excluded from the study. Age, gender, weight, height, body mass index (BMI), status of dentition, presence of beard, Mallampati class, Evaluate 3-3-2 rule and Cormack-Lehane scores were recorded.
The primary outcome measure was to determine the ability of lateral cervical radiography to predict difficult laryngoscopy. The secondary outcome measures were to determine the incidence of difficult laryngoscopy in the study population and to find the usefulness of different laryngoscopy characteristics in predicting difficult laryngoscopy. Before the study, all emergency physicians in the clinic were instructed and made to practice the clinical measurements and classifications. The Mallampati class was evaluated by instructing the patients who could sit and remove their cervical collars to open their mouths as wide as possible, without phonating and in the sitting position. Since the study population consisted of trauma patients, the measurements were performed in the supine position with cervical collars applied in patients with suspected neck trauma and requiring cervical immobilisation. While evaluating mouth opening, the neck was supported and the cervical collar was opened for a short time. Manual-in-line-stabilisation was done during anaesthetic induction.
The Mallampati classification was scored as follows: Grade 1 or 2 = 0 point, Grade 3 or 4 = 1 point; Evaluate (3-3-2) rule; Interincisor distance was evaluated as follows: ≥3-finger width = 0 point, ≤2-finger width = 1 point; the hyomental distance was evaluated as follows: ≥3-finger width = 0 point, ≤2-finger width = 1 point; the thyrohyoid distance was evaluated as follows: 2-finger width = 0 point, 1-finger width = 1 point. This procedure was performed in a neutral position in the patients requiring cervical immobilisation. Cervical radiographs were taken in a neutral position to include the entire mandible. The anterior and posterior mandibular depths, effective mandibular length, atlanto-occipital distance, mandibulohyoid distance, thyromental distance, and distance between the superior temporomandibular joint (TMJ) and the inferior edge of the fourth cervical vertebra were measured on the radiographs [Figure 1]. Cricoid force was used during intubation in all patients. Difficulty in laryngoscopy was determined on the basis of the clinician's opinion. Patients were divided into two groups as the difficult and easy laryngoscopy groups according to the difficulty level of the procedure before intubation, and the basic and measurement parameters were compared between the groups.
|Figure 1: Measurements on cervical X-ray (1) anterior mandibular depth; (2) posterior mandibular depth; (3) effective mandibular length; (4) atlanto-occipital distance; (5) mandibulohyoid distance; (6) thyromental distance; (7) distance between the superior temporomandibular joint and the inferior edge of the fourth cervical vertebra|
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Data were analysed using the Statistical Package for the Social Sciences software, version (SPSS Inc., Chicago, IL, USA) program. Continuous variables were expressed as mean ± standard deviation, while categorical variables were expressed as a number of cases and percentage. One-way analysis of variance was used to calculate the significance of the difference between independent means in normally distributed groups. Logistic regression analysis was performed to determine the probability rates (95% confidence interval) for the risk factors of difficult laryngoscopy. A P < 0.05 was considered statistically significant.
| Results|| |
A total of 97 patients were included in our study; 74 (76.3%) of the patients were male and 23 (23.7%) were female. The mean age was 41.62 ± 17.68 years. The patients were divided into two groups – as the difficult and easy laryngoscopy groups – according to the difficulty level of the procedure as judged before intubation. Of these patients, 54 (55.6%) were in the difficult laryngoscopy group, 43 (44.4%) were in the easy laryngoscopy group. The interincisor, hyomental and thyrohyoid distances were significantly lower in the difficult laryngoscopy group compared to the easy laryngoscopy group. In addition, the percentage of those with a Mallampati class >2 was significantly higher in the difficult laryngoscopy group compared to the easy laryngoscopy group. The parameters measured on cervical radiography did not differ significantly between the groups. Demographic data and measurement parameter values of the groups are given in [Table 1].
|Table 1: Demographic data and airway characteristic in difficult and easy laryngoscopy|
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In univariate analysis, only age was associated with difficult laryngoscopy. In multivariate analysis, none of the parameters such as age, gender, BMI, anterior and posterior mandibular depths, effective mandibular length, atlanto-occipital distance, mandibulohyoid distance, thyromental distance and distance between the superior TMJ and C4 were independent risk factors [Table 2].
|Table 2: Logistic regression analyses showing the different variables to predict difficult laryngoscopy in the study group|
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| Discussion|| |
Difficult intubation is a common problem encountered by every emergency physician in emergency practice, and 1%–18% of all intubations have been reported to result in difficulty. Considering complications such as perforation and oesophageal intubation which may occur during intubation, early evaluation of intubation difficulty gains importance. Many methods have been employed to evaluate intubation difficulty in the emergency department, and a careful examination of the airway is required. Some of these methods are the Mallampati classification and evaluation of thyromental distance, sternomental distance, mouth opening, condition of the tongue, tooth and beard structure, atlanto-occipital space, mandibular angle and distance between the hyoid and body of cervical vertebra., In our study, the parameters measured by lateral cervical radiography including anterior and posterior mandibular depths, effective mandibular length, atlanto-occipital distance, mandibulohyoid distance, thyromental distance and distance between the superior TMJ and the inferior edge of the fourth cervical vertebra were compared in terms of laryngoscopy difficulty, and these measurements were not found to be related to difficulty in laryngoscopy. In addition, the relationship of interincisor, hyomental and thyrohyoid distances with laryngoscopy difficulty was examined, and a significant difference was observed between the groups.
Savva stated that there was no significant relationship between intubation difficulty and age, gender and BMI in their study. Similarly, no relationship was observed between difficult intubation and height and weight in another study. However, Yildiz et al. reported that intubation was more difficult in patients with high BMI in their study. In our study, we observed that age and gender did not have any bearing to difficulty in laryngoscopy.
Previous studies have reported different sensitivity and cut-off values for the interincisor, hyomental and thyrohyoid distances in predicting difficulty in laryngoscopy. Thyromental distance has been shown to have a good predictive ability for difficult intubation in the general population and surgical patients. The interincisor distance is defined as the maximum distance between the incisors. Studies have found that the risk of difficult intubation increased in patients with limited mandibular protrusion and an interincisor distance <5 cm. However, Krobbuaban et al. found no correlation between the laryngoscopy image and interincisor distance in their study. Our study has demonstrated the association of interincisor, hyomental and thyrohyoid distances with laryngoscopy difficulty.
There are studies showing that radiological evaluations can be used as an alternative to bedside clinical tests in determining difficult airway or to strengthen the accuracy of bedside tests. Lateral cervical radiography is one of the preferable methods since it is relatively inexpensive and easily accessible. Samra et al. measured the effective mandibular length, anterior and posterior mandibular depths, atlanto-occipital distance, and C1–C2 space and found that these parameters were not statistically significant in evaluating difficult airway in their study. Jain et al. identified an increase in the posterior mandibular depth, a limitation of C1–C2 movement and low atlanto-occipital distance as the indicators of difficult intubation.
The first limitation of our study is the relatively small sample size and single-centre design. In addition, the majority of patients underwent cervical radiography with cervical collars, since the study population consisted of trauma patients. Vertebral immobilisation was achieved in the patients evaluated as multiple trauma, and the measurements were performed with cervical collars in situ in the supine position. Therefore, the sitting position required for performing the Mallampati test could not be achieved in these patients. This may have caused an inaccurate evaluation of the Mallampati classifications. While evaluating the hyomental and thyrohyoid distances, cervical collars were released for a short time and the measurements were performed accordingly. Another important limitation of our study was that as the difficulty in laryngoscopy was made on the clinician's opinion, this could have introduced an element of bias.
| Conclusion|| |
Our study results show that bedside lateral cervical radiography was not a useful imaging method to identify difficult laryngoscopy in patients of trauma.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Table 1], [Table 2]