Reliability of upper airway assessment using CBCT.

Background: Upper airway analysis is an often-cited use of CBCT imaging by orthodontists; however, the reliability of airway measurements using this technology is not fully established. Objective: To determine the intra-examiner and inter-examiner reliability of the complete process of volumetric and cross-sectional area assessments of the upper airway using CBCT imaging. Materials and Methods: Six examiners of varying levels of education and clinical experience performed the steps necessary for airway analysis, including manual orientation, slice and threshold selection and measured nasopharyngeal, oropharyngeal, hypopharyngeal and total upper pharyngeal airway volumes in addition to minimum cross-sectional area on the CBCT images of 10 patients. All measurements were repeated after 4-weeks. Intra- and inter-examiner reliability was calculated using ICC and 95% CI. Results: Threshold selection showed poor intra- and poor inter-examiner reliability, whereas minimum cross-sectional area showed moderate intra- and poor inter-examiner reliability. Intra-examiner reliability of volumetric measurements varied based on the region assessed with ICC ranging from 0.747 to 0.976, and was worst for hypopharynx and best for the oropharynx. Inter-examiner reliability of volume measurements was generally lower, with ICC ranging from 0.175 to 0.945, and was worst for nasopharynx and best for the oropharynx. Conclusions: This study, for the first time, assessed the reliability of upper airway analysis with CBCT when all steps of image processing and measurement are performed by each examiner. Reliability improved with examiner experience, though was generally low for the hypopharynx and nasopharynx volumes and overall minimal cross-sectional area. The oropharyngeal volume was the only parameter to have excellent intra- and inter-examiner reliability.

Two-dimensional and three-dimensional assessment of the upper airway / Evaluación bidimensional y tridimensional de la vía aérea superior

The aim of this study was to validate and correlate the two-dimensional (2D) with the three-dimensional (3D) measures of the upper airway assessment. Lateral cephalograms and cone beam CT of 100 adult subjects were used to perform a 2D and 3D assessment of the upper airway. Spearman correlation coefficient was used to determine whether there was correlation between variables. Additionally, specificity, sensitivity, negative predictive value and positive predictive value was calculated for the 2D assessment of the upper airway. Correlation between all two and three dimensional variables was found. In the nasopharynx and oropharynx, a weak correlation (r <0.51) was found; in the oropharynx a moderate one (0.50

El objetivo de este estudio fue validar y correlacionar las medidas bidimensionales (2D) con las medidas tridimensionales (3D) de la evaluación de las vías aéreas superiores. Se realizaron cefalogramas laterales y cone beam CT en 100 sujetos adultos para realizar una evaluación 2D y 3D de la vía aérea superior. Se utilizó el coeficiente de correlación de Spearman para determinar si había correlación entre las variables. Además, para la evaluación 2D de la vía aérea superior, se calculó la especificidad, sensibilidad, valor predictivo negativo y valor predictivo positivo. Se encontró correlación en todas las variables entre dos y tres dimensiones. En la nasofaringe y la orofaringe, se encontró una correlación débil (r <0,51) mientras que en la orofaringe moderada (0,50

Assessment of upper airways measurements in patients with mandibular skeletal Class II malocclusion.

OBJECTIVE: Mandibular Class II malocclusions seem to interfere in upper airways measurements. The aim of this study was to assess the upper airways measurements of patients with skeletal Class II malocclusion in order to investigate the association between these measurements and the position and length of the mandible as well as mandibular growth trend, comparing the Class II group with a Class I one. METHODS: A total of 80 lateral cephalograms from 80 individuals aged between 10 and 17 years old were assessed. Forty radiographs of Class I malocclusion individuals were matched by age with forty radiographs of individuals with mandibular Class II malocclusion. McNamara Jr., Ricketts, Downs and Jarabak's measurements were used for cephalometric evaluation. Data were submitted to descriptive and inferential statistical analysis by means of SPSS 20.0 statistical package. Student's t-test, Pearson correlation and intraclass correlation coefficient were used. A 95% confidence interval and 5% significance level were adopted to interpret the results. RESULTS: There were differences between groups. Oropharynx and nasopharynx sizes as well as mandibular position and length were found to be reduced in Class II individuals. There was a statistically significant positive correlation between the size of the oropharynx and Xi-Pm, Co-Gn and SNB measurements. In addition, the size of the nasopharynx was found to be correlated with Xi-Pm, Co-Gn, facial depth, SNB, facial axis and FMA. CONCLUSION: Individuals with mandibular Class II malocclusion were shown to have upper airways measurements diminished. There was a correlation between mandibular length and position and the size of oropharynx and nasopharynx.

Assessment of upper airways measurements in patients with mandibular skeletal Class II malocclusion

Objective: Mandibular Class II malocclusions seem to interfere in upper airways measurements. The aim of this study was to assess the upper airways measurements of patients with skeletal Class II malocclusion in order to investigate the association between these measurements and the position and length of the mandible as well as mandibular growth trend, comparing the Class II group with a Class I one.Methods:A total of 80 lateral cephalograms from 80 individuals aged between 10 and 17 years old were assessed. Forty radiographs of Class I malocclusion individuals were matched by age with forty radiographs of individuals with mandibular Class II malocclusion. McNamara Jr., Ricketts, Downs and Jarabak's measurements were used for cephalometric evaluation. Data were submitted to descriptive and inferential statistical analysis by means of SPSS 20.0 statistical package. Student's t-test, Pearson correlation and intraclass correlation coefficient were used. A 95% confidence interval and 5% significance level were adopted to interpret the results.Results:There were differences between groups. Oropharynx and nasopharynx sizes as well as mandibular position and length were found to be reduced in Class II individuals. There was a statistically significant positive correlation between the size of the oropharynx and Xi-Pm, Co-Gn and SNB measurements. In addition, the size of the nasopharynx was found to be correlated with Xi-Pm, Co-Gn, facial depth, SNB, facial axis and FMA.Conclusion: Individuals with mandibular Class II malocclusion were shown to have upper airways measurements diminished. There was a correlation between mandibular length and position and the size of oropharynx and nasopharynx.

Introdução: as más oclusões de Classe II mandibulares parecem interferir nas dimensões das vias aéreas superiores. Assim, o objetivo do presente estudo foi avaliar as vias aéreas superiores de pacientes com Classe II esquelética, verificando a associação entre essas dimensões e a posição mandibular, o comprimento mandibular e a tendência de crescimento, comparando-os com um grupo pareado de pacientes com Classe I.Métodos: foram avaliadas 80 telerradiografias de perfil de 80 pacientes com 10 a 17 anos de idade, sendo 40 com má oclusão de Classe I e 40 com Classe II mandibular, pareados por idade. Para a avaliação cefalométrica, foram utilizadas medidas de McNamara Jr, Ricketts, Downs e Jarabak. Os dados foram submetidos à análise estatística descritiva e inferencial, por meio dosoftware SPSS 20.0, utilizando-se os testest de Student, coeficiente de correlação de Pearson e coeficiente de correlação intraclasse. Para interpretação dos resultados, adotou-se um intervalo de confiança de 95% e nível de significância de 5%.Resultados: houve diferença entre os grupos, e as medidas da orofaringe e nasofaringe foram menores no grupo de Classe II, assim como as medidas de comprimento e posição mandibular. Houve correlação positiva estatisticamente significativa entre a orofaringe e as medidas Xi-Pm, Co-Gn e SNB; já a nasofaringe apresentou correlação com as medidas Xi-Pm, Co-Gn, profundidade facial, SNB, eixo facial e FMA.Conclusão: indivíduos portadores de Classe II mandibular apresentaram as medidas das vias aéreas superiores diminuídas. Observou-se uma correlação entre o comprimento mandibular e a posição mandibular e as dimensões da orofaringe e da nasofaringe.

Airway Assessment for Office Sedation/Anesthesia.

Whenever a patient is about to receive sedation or general anesthesia, no matter what the technique, the preoperative assessment of the airway is one of the most important steps in ensuring patient safety and positive outcomes. This article, Part III in the series on airway management, is directed at the ambulatory office practice and focuses on predicting the success of advanced airway rescue techniques.

An assessment of oropharyngeal airway position using a fibreoptic bronchoscope.

Selecting the appropriate oropharyngeal airway for safe and effective airway management is important in clinical practice. In this prospective observational study, we examined the position of the distal end of oropharyngeal airways using a fibreoptic bronchoscope. We enrolled 149 adults (72 men and 77 women). The correct airway size was determined by inserting four adult sizes Guedel airway (Hudson RCI; Teleflex Medical, Research Triangle, Park, NC, USA) (sizes 8, 9, 10 and 11) sequentially in anaesthetised patients. The 'best fit' airway was size 10 in 45 (62%) men, and size 9 in 58 (75%) women. However, when these airways were inserted, the distal end of the airway either touched or passed beyond the epiglottis tip in 20 (27%) men and six (8%) women, respectively. When a size-9 airway was inserted in men and a size-8 airway inserted in women, the distal ends were obstructed by the tongue in three (2%) patients. In conclusion, a size-9 airway in men and a size-8 airway in women are the most acceptable sizes for adults of average height.

Volumetric upper airway assessment in patients with transverse maxillary deficiency after surgically assisted rapid maxillary expansion.

Transverse maxillary deficiency is commonly found in patients with sleep apnea and is also related to abnormal breathing patterns. Maxillary expansion procedures promote widening of the nasal floor and reduce the resistance to airflow, and have a positive influence on nasopharynx function. In order to evaluate volume changes in the upper airway, 15 adult patients with transverse maxillary deficiency underwent surgically assisted rapid maxillary expansion (RME) until a slight overcorrection of the crossbite was obtained. Cone beam computed tomography (CBCT) volumetric images were obtained at three predefined time points. The mean age of the patients was 30.2 (±7.4) years; nine were females and six were males. The area, volume, and the smallest transverse section area of the airway were assessed using Dolphin Imaging 3D software. Statistical comparisons were made of the changes between time periods. No statistically significant differences were found for volume or area. However a significant difference was found between the preoperative and immediate postoperative smallest transverse section area (P<0.05). Maxillary expansion, as an isolated procedure, does not result in a statistically significant improvement in the airway dimensions and results in an inferior relocation of the smallest transverse section area.

A comparative study of lateral cephalograms and cone-beam computed tomographic images in upper airway assessment.

The purpose of this study was to evaluate the accuracy of airway measurements from lateral cephalograms, cone-beam computed tomographic (CBCT) lateral reconstructions, and CBCT axial planes, as well as to correlate these findings with area measurements acquired with the latter imaging method. Landmarks were defined for the measurements of naso- and oropharynx of 30 patients (12 males and 18 females, mean age 17.5 years), for different planes, using linear antero-posterior measurements and the corresponding area. Analysis of variance showed significant differences in the linear measurements of the oropharynx between the two methods, although all measurements assessed corresponded to the respective areas. The linear measurements of the airway space obtained using the different techniques correlated positively with the respective area measurements, which demonstrate the reliability of the investigated techniques.

A comparison of preoperative airway assessment techniques: the modified Mallampati and the upper lip bite test.

The purpose of this study was to compare the preoperative anesthetic airway evaluation methods of the modified Mallamapti test (MMT) and upper lip bite test (ULBT) with the direct laryngoscopic views obtained during tracheal intubation. Positive relationships were predicted for the MMT and ULBT with direct laryngoscopic view and between the MMT and ULBT. We assessed 50 patients' airways preoperatively by MMT and ULBT. Intraoperatively, laryngoscopic views were graded on the Cormack and Lehane scale. Descriptive statistics and correlations were computed. There was no relationship between the MMT and the ULBT and the Cormack and Lehane scale. There was a significant relationship between the ULBT and the Cormack and Lehane scale (r = 0.512; P <.001 ). The ULBT was superior to the MMT in every measure in this study: sensitivity (55% vs 11%), specificity (97% vs 75%), positive predictive value (83% vs 9%), and accuracy (90% vs 64%). The findings of this study support those of a previous study of the ULBT. Because of the ease of the ULBT and the promising results of this small study, we recommend further research with a larger, more diverse sample.

Risk factors assessment of the difficult airway: an italian survey of 1956 patients.

Over the last decade, there has been a heightened awareness and an increase in the amount of literature being published on recognition and prediction of the difficult airway. During the preoperative evaluation of the airway, a thorough history and physical specifically related to the airway should be performed. Various measurements of anatomic features and noninvasive clinical tests can be performed to enhance this assessment. In this study we correlated the Mallampati modified score and several other indexes with the laryngoscopic view to identify anatomical and clinical risk factors related to the difficult airway. We prospectively collected data on 1956 consecutive patients scheduled to receive general anesthesia requiring endotracheal intubation for elective surgery. The Mallampati classification versus the Cormack-Lehane (C-L) linear correlation index was 0.904. A Mallampati Class 3 correlated with a C-L Grade 2 (0.94), whereas a Mallampati Class 4 correlated with a C-L Grade 3 (0.85) and a C-L Grade 4 (0.80). Operator evaluation, performed by a simplified tracheal intubation difficulty scale, showed a linear correlation of 0.96 compared with the C-L groups. Although there is a correlation between oropharyngeal volume and difficult intubation, the Mallampati score by itself is insufficient for predicting difficult endotracheal intubation.

Assessment of oropharyngeal distance in children using magnetic resonance imaging.

UNLABELLED: Rational determination of oral airway size in children must account for the oropharyngeal length. We used magnetic resonance imaging (MRI) to measure the distance from the teeth/gums to the prevertebral pharyngeal space and created algorithms to predict this distance based on age, weight, and gender. After institutional review board approval, we reviewed 200 MRI head scans of children 0-17 yr old. Patient information, including midline distance from teeth/gums to prevertebral space (L1) and distance along a perpendicular line from L1 to the epiglottis tip (L2), was recorded. Two groups (Group 1 (n = 100) training group, Group 2 (n = 100) validation group) were then randomly selected from this sample. Predictive models created using Group 1 were tested using Group 2 as the sample group. Oropharyngeal distance was related to age, weight, and gender. A prediction equation using all data was estimated to determine the final model: predicted L1 = 5.51 + 0.25 (age [years]) -0.01 (age2) + 0.02 (weight [kg]) + 0.12 (male). We report equations to predict the oropharyngeal distance based on age, weight, and gender in children. The oral airway size will be 1-2 cm longer than these measurements to position the tooth/lip guard outside the lip. Variability in the distance to the epiglottis must be considered when selecting proper oral airway size for any child. This information will provide the foundation for a more rational determination of the proper oral airway size for infants and children. IMPLICATIONS: Age, weight, and gender can be used to predict the length of the oropharynx in children as determined by midline sagittal magnetic resonance image of the airway. Prediction of this length will lead to a more rational determination of proper oral airway size for infants and children and, potentially, more effective airway management.

Preoperative airway assessment: predictive value of a multivariate risk index.

Using readily available and objective airway risk criteria, a multivariate model for stratifying risk of difficult endotracheal intubation was developed and its accuracy compared to currently applied clinical methods. We studied 10,507 consecutive patients who were prospectively assessed prior to general anesthesia with respect to mouth opening, thyromental distance, oropharyngeal (Mallampati) classification, neck movement, ability to prognath, body weight, and history of difficult tracheal intubation. After induction of anesthesia, the laryngeal view during rigid laryngoscopy was graded and the ability of experienced anesthesia personnel to ventilate via a mask was determined. Poor intubating conditions (laryngoscopy Grade IV) and inability to achieve adequate mask ventilation were identified in 107 (1%) and 8 (0.07%) cases, respectively. Logistic regression identified all seven criteria as independent predictors of difficulty with laryngoscopic visualization. A composite airway risk index (derived from nominalized odds ratios calculated from the multivariate model) as well a simplified (0 = low, 1 = medium, 2 = high) risk weighting exhibited higher positive predictive value for laryngoscopy Grade IV at scores with similar sensitivity to Mallampati class III, as well as higher sensitivity at scores with similar positive predictive value. Compared to Mallampati class I fewer false-negative predictions were observed at a risk index value of 0. We conclude that improved risk stratification for difficulty with visualization during rigid laryngoscopy (Grade IV) can be obtained by use of a simplified preoperative multivariate airway risk index, with better accuracy compared to oropharyngeal (Mallampati) classification at both low- and high-risk levels.

Assessment of upper airway anatomy in awake, sedated and anaesthetised patients using magnetic resonance imaging.

Magnetic Resonance Imaging was used to quantify the effects of 1. sedation and 2. general anaesthesia with a laryngeal mask airway (LMA) in place on the minimum antero-posterior (A-P) diameters of the naso-, oro- and hypopharynx and on the angle of the epiglottis relative to the adjacent posterior pharyngeal wall. Median sagittal T1-weighted images of the pharynx were obtained in 46 patients (16 awake, 14 sedated, 16 under general anaesthesia). In sedated patients, the A-P diameters of the pharynx were less than in awake patients, in particular at the levels of the epiglottis and soft palate. General anaesthesia and placement of a LMA was also associated with a reduced A-P diameter at the level of the soft palate, but with increased diameters at the levels of the tongue and epiglottis. Placement of a LMA caused abnormal downfolding of the epiglottis in most cases but this did not cause clinically significant airway obstruction.