Anterior neck soft tissue measurements on computed tomography to predict difficult laryngoscopy: a retrospective study.

Predicting difficult laryngoscopy is an essential component of the airway management. We aimed to evaluate the use of anterior neck soft tissue measurements on computed tomography for predicting difficult laryngoscopy and to present a clear measurement protocol. In this retrospective study, 281 adult patients whose tracheas were intubated using a direct laryngoscope for thyroidectomy were enrolled. On computed tomography, the distances from the midpoint of the thyrohyoid membrane to the closest concave point of the vallecular (membrane-to-vallecula distance; dMV), and to the most distant point of the epiglottis (membrane-to-epiglottis distance; dME) were measured, respectively. The extended distances straight to the skin anterior from the dMV and dME were called the skin-to-vallecula distance (dSV) and skin-to-epiglottis distance (dSE), respectively. Difficult laryngoscopy was defined by a Cormack-Lehane grade of > 2. Difficult laryngoscopy occurred in 40 (14%) cases. Among four indices, the dMV showed the highest prediction ability for difficult laryngoscopy with an area under the receiver operating characteristic curve of 0.884 (95% confidence interval 0.841-0.919, P < 0.001). The optimal dMV cut-off value for predicting difficult laryngoscopy was 2.33 cm (sensitivity 75.0%; specificity 93.8%). The current study provides novel evidence that increased dMV is a potential predictive indicator of difficult laryngoscopy.

Measurement of subglottic diameter and distance to pre-epiglottic space among Chinese adults.

Proper endotracheal tube (ETT) size selection and identification of potentially difficult airways are important to reduce laryngeal injury during intubation. However, controversies exist concerning transverse subglottic diameter-the narrowest part of the airway-and the distance to pre-epiglottic space. Because few studies have reported the distance from skin to the midpoint of the epiglottis (DSE) among normal individuals, whether the DSE varies between individuals and by ethnicity remains uncertain. The present study aims to investigate the sonographic subglottic diameter and DSE among healthy Chinese adults. Healthy volunteers were recruited at National Taiwan University Hospital between October and November 2019. Exclusion criteria included pre-existing airway or respiratory diseases, neck tumors, and a history of neck operation. Age, sex, height, weight, body mass index (BMI), sonographic DSE, and transverse subglottic diameter were recorded. A total of 124 participants were enrolled. The average age was 32.5 ± 10.4 years and 63 participants (51%) were males. The subglottic diameter was positively associated with sex (males, 14.40 mm; females, 11.10 mm, p < 0.001) and BMI (underweight, 12.13 mm; normal weight, 12.47 mm; overweight, 13.80 mm; obese, 13.67 mm, p = 0.007). Moreover, the DSE was shorter in males (male, 16.18 mm; females, 14.54 mm, p < 0.001) and participants with increased BMI (underweight, 13.70 mm; normal weight, 15.06 mm; overweight, 16.58 mm; obese, 18.18 mm, p < 0.001). As compared with other ethnicity, a smaller size of subglottic diameter and a shorter DSE were noted among Chinese participants, and we suggest that a relatively smaller size of endotracheal tube selection should be considered in tracheal intubations.

Automatic vocal tract landmark localization from midsagittal MRI data.

The various speech sounds of a language are obtained by varying the shape and position of the articulators surrounding the vocal tract. Analyzing their variations is crucial for understanding speech production, diagnosing speech disorders and planning therapy. Identifying key anatomical landmarks of these structures on medical images is a pre-requisite for any quantitative analysis and the rising amount of data generated in the field calls for an automatic solution. The challenge lies in the high inter- and intra-speaker variability, the mutual interaction between the articulators and the moderate quality of the images. This study addresses this issue for the first time and tackles it by means of Deep Learning. It proposes a dedicated network architecture named Flat-net and its performance are evaluated and compared with eleven state-of-the-art methods from the literature. The dataset contains midsagittal anatomical Magnetic Resonance Images for 9 speakers sustaining 62 articulations with 21 annotated anatomical landmarks per image. Results show that the Flat-net approach outperforms the former methods, leading to an overall Root Mean Square Error of 3.6 pixels/0.36 cm obtained in a leave-one-out procedure over the speakers. The implementation codes are also shared publicly on GitHub.

Effects of Angle of Epiglottis on Aerodynamic and Acoustic Parameters in Excised Canine Larynges.

OBJECTIVES: The aim of this study is to explore the effects of the angle of epiglottis (Aepi) on phonation and resonance in excised canine larynges. METHODS: The anatomic Aepi was measured for 14 excised canine larynges as a control. Then, the Aepis were manually adjusted to 60° and 90° in each larynx. Aerodynamic and acoustic parameters, including mean flow rate, sound pressure level, jitter, shimmer, fundamental frequency (F0), and formants (F1'-F4'), were measured with a subglottal pressure of 1.5 kPa. Simple linear regression analysis between acoustic and aerodynamic parameters and the Aepi of the control was performed, and an analysis of variance comparing the acoustic and aerodynamic parameters of the three treatments was carried out. RESULTS: The results of the study are as follows: (1) the larynges with larger anatomic Aepi had significantly lower jitter, shimmer, formant 1, and formant 2; (2) phonation threshold flow was significantly different for the three treatments; and (3) mean flow rate and sound pressure level were significantly different between the 60° and the 90° treatments of the 14 larynges. CONCLUSIONS: The Aepi was proposed for the first time in this study. The Aepi plays an important role in phonation and resonance of excised canine larynges.

Upper airway in children with unilateral cleft lip and palate evaluated with computational fluid dynamics.

INTRODUCTION: Children with unilateral cleft lip and palate (UCLP) exhibit snoring and mouth breathing. They are also reported to show obstructive sleep apnea syndrome. However, their upper airway ventilation condition is not clearly understood. Therefore, this study was performed to evaluate upper airway ventilation condition in children with UCLP with the use of computational fluid dynamics. METHODS: Twenty-one children (12 boys, 9 girls; mean age 9.1 years) with UCLP and 25 children (13 boys, 12 girls; mean age 9.2 years) without UCLP who required orthodontic treatment underwent cone-beam computed tomography (CBCT). Nasal resistance and upper airway ventilation condition were evaluated with the use of computational fluid dynamics from CBCT data. The groups were compared with the use of Mann-Whitney U tests and Student t tests. RESULTS: Nasal resistance of the UCLP group (0.97 Pa/cm3/s) was significantly higher than that of the control group (0.26 Pa/cm3/s; P < 0.001). Maximal pressure of the upper airway (335.02 Pa) was significantly higher in the UCLP group than in the control group (67.57 Pa; P < 0.001). Pharyngeal airway (from choanae to base of epiglottis) pressure in the UCLP group (140.46 Pa) was significantly higher than in the control group (15.92 Pa; P < 0.02). CONCLUSIONS: Upper airway obstruction in children with UCLP resulted from both nasal and pharyngeal airway effects.

The nasopharyngeal airway: Estimation of the nares-to-mandible and nares-to-tragus distance in young children to assess current clinical practice.

BACKGROUND: Nasopharygeal airways are used in urgent situations to alleviate airway obstruction. Guidelines for measuring the length of the NPA differ between national and international guidelines, and the evidence base for these measurements is lacking. The purpose of this study was to measure the nares-epiglottis and nares-vocal cord distances in young children (neonates to 12 years) on 3D reconstructed Magnetic Resonance Imaging (MRI) brain volume scans, and to examine the relationship of these distances with the nares-tragus and nares-mandible distances. METHOD: One-hundred and seventy-six scans were reviewed. All patients had undergone MRI 3D brain volume imaging. The anatomical landmarks were identified and the nares-tragus, nares-mandible distances measured and compared to nares-epiglottis and nares-vocal cord distance using Osirix. RESULTS: The nares-epiglottis and nares-vocal cords distances significantly correlated (p-value <0.05). The nares-tragus distance showed strong correlation with the nares-epiglottis and nares-vocal cord distance compared to the nares-mandible distance (p-value <0.05). CONCLUSION: In conclusion, the length of a nasopharyngeal airway in children under the age of twelve years can be predicted using the nares-tragus external anatomical distance minus 10 mm.

Scanning electron microscopy and histomorphology of the epiglottis in dromedaries: A study revealing unusual structure with the probable functional role.

While epiglottis is essentially a mammalian structure, studying its microstructure in any placental model will add an important information to the field of comparative anatomy and the related branches of biology. The aim of this study was to describe the structure of the epiglottis in dromedary camels using light and scanning electron microscopy (SEM), with reference to the possible functions. A total of 11 epiglottis cartilages from 11 larynges were used. The study revealed unusual, deeply situated glands just beneath the cartilage plate. They have unusually, wide surface-openings, while their ducts were partly located within the cartilage. This is presumed to be an adaptation to the need for rapid and efficient mucosal surface hydration in the arid conditions. The possible secretion transport mechanisms in these glands were also discussed. Furthermore, the SEM revealed for the first time, the presence of taste buds in camel epiglottis. However, in histological sections, visibility of taste buds was dependent upon the staining techniques. The taste buds were not seen with standard H& E stain, as they blended imperceptibly with the surrounding epithelium. Conversely, Mallory's trichrome showed contrasting colors, and taste buds were visible. In conclusion, camel epiglottis has an unusual structure, which may be correlated to environmental adaptation and important for the general health of upper respiratory tract in this species.

Estimation of nares-to-epiglottis distance for selecting an appropriate nasopharyngeal airway.

The nasopharyngeal airway is an important equipment in airway management, a correct placement is crucial for its effectiveness. We measured the nares-to-epiglottis distance (NED) and examined the correlations of the optimal insertion length (NED-1) with patient characteristics and various external facial measurements. We aimed to develop a simple method for estimating the optimal insertion length and to help select an appropriate nasopharyngeal airway.Two hundred patients of ASA grade I & II aged >20 years undergoing elective surgery under general anesthesia were enrolled. We measured nares-to-ear tragus distance (NTD), nares-to-mandibular angle distance (NMD), philtrum-to-ear tragus distance (PTD), and philtrum-to-mandibular angle distance (PMD). The NED was measured by fiber-optic bronchoscope. All measurements were obtained in centimeters. NED-1 (cm) was defined as the optimal insertion length. The patient's sex, age, body weight, body height, and body mass index were recorded.The NED-1 significantly correlated with body weight, body height, NTD, NMD, PTD, and PMD. Backward stepwise multiple linear regression analysis yielded the formula for predicting NED-1: 0.331 - 0.018 × BW + 0.061 × BH + 1.080 × NMD - 1.256 × PMD + 0.697 × PTD (r = 0.640, P < .001). The regression lines of the optimal insertion length versus PTD showed the best fit to the equality line. The measurements of PTD showed the minimal differences from NED-1 and with the most patients showing <1 cm differences from NED-1.The optimal insertion depth of nasopharyngeal airway can easily be predicted by the distance from philtrum-to-ear tragus, and a nasopharyngeal airway of an appropriate size can be selected accordingly.

Evaluation of Normal Epiglottis on Computed Tomography with Special Attention to Thickness.

To our knowledge, this is the first study to investigate the thickness of the normal epiglottis on computed tomography (CT) in a Japanese population. The focus was on determining the thickness of a normal epiglottis, which could then serve as a reference in detecting abnormalities. We believe that this would facilitate diagnosing and determining the extent of cancerous invasion of the supraglottis and secondary invasion of the epiglottis. This retrospective study was based on a review of radiographic data in patient charts. Cervical CT scans obtained from 79 Japanese patients (44 men [55.7%] and 35 women [44.3%]; age range, 28-85 years; mean, 58.9 years) showing a normal epiglottis under laryngoscopy were evaluated. The thickness of the epiglottis was measured on CT scans and the results analyzed with the Student's t-test, an analysis of variance, and the Tukey-Kramer test. The epiglottis in men was significantly thicker than that in women (p<0.05). A statistically significant difference was observed in thickness depending on longitudinal height (p=<0.001). The thickness at the median was larger than that bilaterally in all patients (p=<0.001). No statistically significant difference was observed in thickness depending on side or age. The thickness of the normal epiglottis was established at each level. We believe that these data could serve as a reference in diagnosing and detecting abnormalities of the epiglottis.

Morphofunctional evaluation of buccopharyngeal space using three-dimensional cone-beam computed tomography (3D-CBCT).

The present study aims to identify the anatomical functional changes of the buccopharyngeal space in case of singers with canto voice. The interest in this field is particularly important in view of the relation between the artistic performance level, phoniatry and functional anatomy, as the voice formation mechanism is not completely known yet. We conducted a morphometric study on three soprano voices that differ in type and training level. The anatomical soft structures from the superior vocal formant of each soprano were measured on images captured using the Cone-beam Computed Tomography (CBCT) technique. The results obtained, as well as the 3D reconstructions emphasize the particularities of the individual morphological features, especially in case of the experienced soprano soloist, which are found to be different for each anatomical soft structure, as well as for their integrity. The experimental results are encouraging and suggest further development of this study on soprano voices and also on other types of opera voices.

Radiologic indicators for prediction of difficult laryngoscopy in patients with cervical spondylosis.

BACKGROUND: We identified the most useful variables for prediction of difficult laryngoscopy in patients with cervical spondylosis according to physical indicators and preoperative skeletal X-ray and soft tissue MRI measurements. We hypothesized that there was a closer association between difficult laryngoscopy and radiologic indicators. METHODS: We randomly enroled 315 patients undergoing elective cervical spine surgery and analysed the radiological and physical data in predicting difficult laryngoscopy. RESULTS: We identified five variables that were most useful in predicting difficult laryngoscopy: the inter-incisor gap (P = 0.006), modified Mallampati test score (P = 0.004), distance from the highest point of the hyoid bone to the mandibular body (P < 0.001), most antero-inferior point of the upper central incisor tooth (P < 0.001), and length of the epiglottis (P = 0.002). Binary multivariate logistic regression analyses identified three factors that were independently associated with difficult laryngoscopy: the Mallampati score, distance from the hyoid bone to the mandibular body, and the anterior-inferior point of the upper central incisor tooth. The odds ratios and 95% confidence intervals were 1.547 (1.029-2.327), 1.222 (1.139-1.310), and 1.224 (1.133-1.322), respectively. The AUC for hyoid bone distance to mandibular body (0.832) was larger than that of anterior-inferior point of the upper central incisor tooth (0.802, P > 0.05) and that of modified Mallampati test (0.602, P < 0.05). CONCLUSION: Distance from the highest point of the hyoid bone to the mandibular body appears to be the most accurate indicator for difficult laryngoscopy in patients with cervical spondylosis.

Surface anatomy of major anatomical landmarks of the neck in an adult population: A Ct Evaluation of Vertebral Level.

To compare the projectional surface anatomy of healthy individuals in an adult population with those with a thyroid mass, using computed tomography (CT). Sixteen slice CT images of 101 individuals were analyzed using a 32-bit Radiant DICOM viewer to establish the relationships among major anatomical landmarks in the neck and their vertebral levels. The structures investigated included: hard palate (HP), hyoid bone (HB) including body and lesser horns, soft palate (SP), thyroid gland (TG) (both superior and inferior poles), thyroid gland anteroposterior (APD) and superoinferior (SID) diameters, thyroid isthmus (TI) superoinferior dimension, epiglottis, vertebral arteries (right and left), and both right and left parotid glands (superior and inferior extents). The vertebral levels noted most frequently were: body of hyoid bone (C4, 42.71%); lesser horns of hyoid bone (C3, 36.46%); thyroid gland superior pole (C6, 31.25%); and thyroid gland inferior pole (T2, 30.2%). TG-ID, TG-APD, and TG-SID were not significantly different between males and females in the healthy group; however, there was a significant gender difference in thyroid gland inferior diameter in the pathology group [males 2.16(±1.16) vs. females 3.37(±1.30), P = 0.01, paired sample t-test]. Further studies are needed to determine whether neck pathology in those with a thyroid mass affects the dimensions of the thyroid gland. Moreover, the surface anatomy of the neck should be revisited using modern imaging techniques to address inconsistencies in anatomy and clinical reference texts. Clin. Anat. 30:781-787, 2017. © 2017Wiley Periodicals, Inc.

Anatomy of the larynx and pharynx: effects of age, gender and height revealed by multidetector computed tomography.

Although oropharyngeal and laryngeal structures are essential for swallowing, the three-dimensional (3D) anatomy is not well understood, due in part to limitations of available measuring techniques. This study uses 3D images acquired by 320-row area detector computed tomography ('320-ADCT'), to measure the pharynx and larynx and to investigate the effects of age, gender and height. Fifty-four healthy volunteers (30 male, 24 female, 23-77 years) underwent one single-phase volume scan (0.35 s) with 320-ADCT during resting tidal breathing. Six measurements of the pharynx and two of larynx were performed. Bivariate statistical methods were used to analyse the effects of gender, age and height on these measurements. Length and volume were significantly larger for men than for women for every measurement (P < 0.05) and increased with height (P < 0.05). Multiple regression analysis was performed to understand the interactions of gender, height and age. Gender, height and age each had significant effects on certain values. The volume of the larynx and hypopharynx was significantly affected by height and age. The length of pharynx was associated with gender and age. Length of the vocal folds and distance from the valleculae to the vocal folds were significantly affected by gender (P < 0.05). These results suggest that age, gender and height have independent and interacting effects on the morphology of the pharynx and larynx. Three-dimensional imaging and morphometrics using 320-ADCT are powerful tools for efficiently and reliably observing and measuring the pharynx and larynx.

Hallazgo inusual en la valoración de la vía aérea / Unusual finding in the assessment of the airway

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Effect of a neck collar on upper airway size in children sedated with propofol-midazolam combination during magnetic resonance imaging.

INTRODUCTION: Propofol and midazolam are widely used for pediatric magnetic resonance imaging (MRI) sedation. Increasing depth of sedation may be associated with airway obstruction. A neck collar supporting the mandible and maintaining the head in slight extension may be beneficial in maintaining airway patency. AIM OF THE STUDY: Primary aim: To assess upper airway size with and without a neck collar during pediatric MRI sedation with propofol-midazolam. Secondary aim: To evaluate complications encountered during the procedure. MATERIALS AND METHODS: Sixty patients aged 2-4 years scheduled for MRI of the brain were selected. They were sedated with intramuscular midazolam 0.1 mg·kg(-1) 30 min before the procedure. Patients were sedated with i.v. propofol 1 mg·kg(-1) and continued with 50-100 µg·kg(-1) ·min(-1) . T1 3D fast-field echo axial sequence from the nasopharyngeal roof to subglottic region was taken with and without application of a neck collar. Airway dimensions were measured and analyzed at the base of the tongue, soft palate, and at the epiglottis. RESULTS: At the base of the tongue and soft palate, the cross-sectional area (CSA) and the anteroposterior diameter of the airway were respectively statistically significantly higher when the neck collar was applied. The CSA at the epiglottis was significantly less with application of the neck collar. Complications were not significantly different between the two sequences. CONCLUSION: Application of a soft neck collar in children aged 2-4 years may enhance the retropalatal and retroglossal airway dimensions during pediatric sedation in the supine position.

Tongue Size and Posterior Airway Space Changes in Class III Malocclusion After Maxillomandibular Surgery: A Retrospective Study.

The purpose of this study was to evaluate the changes in the airway space after surgical correction of Class III skeletal dentofacial deformity and to determine if orthognathic surgery alters the airway space and improves obstructive sleep apnea. Twenty-four Class III adults treated with orthognathic surgery were divided into two groups as Mandibular set-back (Bilateral Sagittal Split Osteotomy-BSSO, 10 patients) and two jaw surgery (Bilateral Sagittal Split Osteotomy combined with Le Fort I maxillary advancement, 14 patients). Lateral cephalometric radiographs were traced before (T0) and 6 months after surgery (T1). Steiner and McNamara analysis, linear pharyngeal airway measurements (PNS-PPW1, SPT-PPW2, E-PPW3, PNS-SPT), tongue volume measurements (TH, Tt-Eb) and pharyngeal area measurements (nasopharyngeal, upper oropharyngeal, lower oropharyngeal, epiglottis area) were performed. The data obtained was analyzed statistically by repeated measurement ANOVA and Duncan's test. The increase of PNS-PPW1 was important in two jaw surgery group (p < 0.05). The nasopharyngeal area was statistically different between T0 and T1 (p < 0.01), and the lower oropharyngeal area was statistically significant between BSSO and two jaw surgery groups (p < 0.05). Surgical correction of Class III skeletal dentofacial deformity alters posterior airway dimensions. Two jaw surgery is advantageous considering the risk for obstructive sleep apnea, because it evokes an increase in the upper pharyngeal airway dimensions. Keywords: Tongue size, posterior airway space, maxillomandibular surgery.

Comparison of the laryngoscopy views with the size 1 Miller and Macintosh laryngoscope blades lifting the epiglottis or the base of the tongue in infants and children <2 yr of age.

BACKGROUND: Miller laryngoscope blades are preferred for laryngoscopy in infants and children <2 yr of age. Despite their long history, the laryngeal view with the Miller blade size 1 has never been compared with that with the Macintosh (MAC) blade in children. This prospective, single-blinded, randomized study was designed to compare the laryngeal views with the size 1 Miller and MAC blades in children <2 yr. METHODS: With IRB approval, 50 ASA I and II children <2 yr undergoing elective surgery were enrolled. After an inhalation induction and neuromuscular block with i.v. rocuronium 0.5 mg kg(-1), two laryngeal views were obtained with a single blade (Miller or MAC) in each child: one lifting the epiglottis and another lifting the tongue base. The best laryngeal views in each blade position were photographed with a SONY(®) Cyber-shot camera and rated by a blinded anaesthesiologist using the percentage of glottic opening scale. RESULTS: The scores with the Miller blade lifting the epiglottis and the MAC blade lifting the tongue base were similar. The scores with the Miller blade lifting the epiglottis and the tongue base were similar. The scores for the MAC blade lifting the tongue base were greater than those lifting the epiglottis (95% confidence interval: 7.6-26.8) (P=0.0004). CONCLUSIONS: In infants and children <2 yr of age, optimal laryngeal views may be obtained with either the Miller size 1 blade lifting the epiglottis or with the Miller or MAC blades lifting the tongue base. CLINICAL TRIAL REGISTRATION: NCT01717872 at Clinical Trials.gov.

Pharyngeal diameter in various head and neck positions during exercise in sport horses.

BACKGROUND: In equine athletes, dynamic stenotic disorders of the upper airways are often the cause for abnormal respiratory noises and/or poor performance. There are hypotheses, that head and neck flexion may influence the morphology and function of the upper airway and thus could even induce or deteriorate disorders of the upper respiratory tract. Especially the pharynx, without osseous or cartilaginous support is prone to changes in pressure and airflow during exercise. The objective of this study was to develop a method for measuring the pharyngeal diameter in horses during exercise, in order to analyse whether a change of head-neck position may have an impact on the pharyngeal diameter. RESULTS: Under the assumption that the width of the epiglottis remains constant in healthy horses, the newly developed method for calculating the pharyngeal diameter in horses during exercise is unsusceptible against changes of the viewing-angle and distance between the endoscope and the structures, which are to be assessed. The quotient of the width of the epiglottis and the perpendicular from a fixed point on the dorsal pharynx to the epiglottis could be used to determine the pharyngeal diameter. The percentage change of this quotient (pharynx-epiglottis-ratio; PE-ratio) in the unrestrained head-neck position against the reference position was significantly larger than that of any other combination of the head-neck positions investigated. A relation between the percentage change in PE-ratio and the degree of head and neck flexion could not be confirmed. CONCLUSIONS: It could be shown, that the pharyngeal diameter is reduced through the contact position implemented by the rider in comparison to the unrestrained head and neck position. An alteration of the pharyngeal diameter depending on the degree of head and neck flexion (represented by ground and withers angle) could not be confirmed.

Is video laryngoscope-assisted flexible tracheoscope intubation feasible for patients with predicted difficult airway? A prospective, randomized clinical trial.

BACKGROUND: Failed intubation may result in both increased morbidity and mortality. The combination of a video laryngoscope and a flexible tracheoscope used as a flexible video stylet may improve the success rate of securing a difficult airway. We tested the hypothesis that this combination is a feasible way to facilitate intubation in patients with a predicted difficult airway in that it will shorten intubation times and reduce the number of intubation attempts. METHODS: We conducted a randomized, prospective trial in 140 patients with anticipated difficult airways undergoing elective or urgent surgery. After insertion of video laryngoscope, patients were randomly assigned to either having their tube placed with the use of a preformed stylet (control group) or with a flexible tracheoscope (intervention group). The primary outcome measures were time to successful intubation and number of intubation attempts. RESULTS: The number of intubations requiring 2 or more intubation attempts was similar in the 2 groups (14% control vs 13% intervention, P = 1.0); the number of patients requiring 3 or more intubation attempts was not significantly different (8.6% control vs 1.4% intervention, P = 0.12). Distribution for time to intubation also did not differ between the control (median of 66 seconds, interquartile range 47-89) and the intervention group (median of 71 seconds, interquartile range 52-100; P = 0.35). In the control group, 4 patients, all with cervical spine pathology, had the trachea intubated successfully with the video laryngoscope plus flexible tracheoscope after 3 failed attempts with video laryngoscope and rigid stylet. For these 4 patients, time from the decision to change the intubation method to successful intubation with a flexible tracheoscope was 36 ± 14 seconds. Overall success probability for cervical spine patients was 100% (20/20) in the intervention group and 80% (16/20) in the control group, with an exact 95% confidence interval for the difference of 1.4% to 44%, P = 0.04. CONCLUSIONS: Flexible tracheoscope-assisted video laryngoscopic intubation is a feasible alternative to video laryngoscope only intubation in patients with predicted difficult airways. A flexible tracheoscope used in combination with video laryngoscope may also further increase the success rate of intubation in select patients with a proven difficult airway, particularly when in-line stabilization is required.