Length of the Cricoid and Trachea in Children: Predicting Intubation Depth to Prevent Subglottic Stenosis.

OBJECTIVE: Define the length of the subglottis and trachea in children to predict a safe intubation depth. METHODS: Patients <18 years undergoing rigid bronchoscopy from 2013 to 2020 were included. The carina and inferior borders of the cricoid and true vocal folds were marked on a bronchoscope and distances were measured. Patient age, weight, height, and chest height were recorded. Four styles of cuffed pediatric endotracheal tubes (ETT) were measured and potential positions of each cuff and tip were calculated within each trachea using five depth of intubation scenarios. Multivariate linear regression was performed to identify predictors of subglottic and tracheal length. RESULTS: Measurements were obtained from 210 children (141 male, 69 female), mean (SD) age 3.21 (3.66) years. Patient height was the best predictor of subglottic length (R2 : 0.418): Lengthsg (mm) = 0.058 * height (cm) + 2.8, and tracheal length (R2 : 0.733): Lengtht (mm) = 0.485 * height (cm) + 21.3. None of the depth of intubation scenarios maintained a cuff-free subglottis for all ETT styles investigated. A formula for depth of intubation: Lengthdi (mm) = 0.06 * height (cm) + 8.8 found that no ETT cuffs would be in the subglottis and all tips would be above the carina. CONCLUSION: Current strategies for determining appropriate depth of intubation pose a high risk of subglottic ETT cuff placement. Placing the inferior border of the vocal cords 0.06 * height (cm) + 8.8 from the superior border of the inflated ETT cuff may prevent subglottic cuff placement and endobronchial intubation. LEVEL OF EVIDENCE: 4 Laryngoscope, 132:S1-S10, 2022.

Ultrasound guided paralaryngeal pressure versus cricoid pressure on the occlusion of esophagus: a crossover study.

The primary objective of this study is to compare the effectiveness of cricoid pressure (CP) and paralaryngeal pressure (PLP) on occlusion of eccentric esophagus in patients under general anesthesia (GA). Secondary objectives include the prevalence of patients with central or eccentric esophagus both before and after GA, and the success rate of CP in occluding centrally located esophagus in patients post GA. Fifty-one ASA physical status I and II patients, undergoing GA for elective surgery were enrolled in this study. Ultrasonography imaging were performed to determine the position of the esophagus relative to the trachea: (i) before induction of GA, (ii) after GA before external CP maneuver, (iii) after GA with CP, and (iv) after GA with PLP. CP was applied to all patients whilst PLP via fingertip technique was only applied to patients with an eccentric esophagus. Among a total of 51 patients, 28 of them (55%) had eccentric esophagus pre GA, while this number increase to 33 (65%) after induction of GA. CP success rate was 100% in 18 patients with central esophagus post GA versus 27% in 33 patients with eccentric esophagus post GA (P<0.00001). Overall success rate for CP was 53%. In 33 patients with eccentric esophagus anatomy post GA, PLP success rate was 30% compared with 27% with CP (P=1.000). Ultrasound guided PLP fingertips technique was not effective in patients with an eccentrically located esophagus post GA. Ultrasound guided CP achieved 100% success rate in patients with a centrally located esophagus post GA.

Caracterización de estructuras anatómicas de la laringe por ultrasonografía / Characterization of anatomical structures of the larynx by ultrasonography

La laringe es un órgano impar situado en la línea mediana del cuello, compuesto por cartílagos, músculos y ligamentos. La TC y la RM se realizan como técnicas de imagen de primera elección en el estudio de la laringe, no obstante, no están exentas de limitaciones. La ecografía es un método accesible, de alta resolución y presenta una relativa buena visualización de las diferentes estructuras de la laringe. El objetivo del trabajo fue determinar las características de estructuras anatómicas de la laringe identificables ecográficamente. En este trabajo de carácter observacional descriptivo de corte transversal prospectivo se estudiaron 20 pacientes, sin patología laríngea con edades entre 20 y 35 años, ambos sexos. Se realizó ecografía laríngea utilizando transductor ecográfico Phillips® con sonda lineal de 4 a 12 MHz, preset de partes blandas.En todos los casos se pudo identificar y medir los cartílagos tiroides, cricoides y epiglotis; y en gran porcentaje de estos las cuerdas vocales, bandas ventriculares y comisura anterior. El cartílago aritenoides solo fue visible en un 85% de los casos.La ecografía se presenta como un método auxiliar útil en el estudio de la anatomía de la laringe, proponiendo el seguimiento y realización de estudios ulteriores que puedan complementar este estudio y su validez.

The larynx is an odd organ located in the midline of the neck, composed of cartilage, muscles and ligaments. CT and MRI are performed as first-choice imaging techniques in the larynx study; however, they are not without limitations. Ultrasound is an accessible, high-resolution method with a relatively good visualization of the different structures of the larynx. The objective of the work was to determine the characteristics of ultrasoundly identifiable larynx anatomical structures.In this prospective cross-sectional descriptive observational work, 20 patients were studied, without laryngeal pathology aged between 20 and 35 years, both sexes. Laryngeal ultrasound was performed using Phillips® ultrasound transducer with linear probe from 4 to 12 MHz, soft parts presetThyroid cartilage, cricoids and epiglotis could be identified and measured in all cases, and in a large percentage of these the vocal cords, ventricular bands and anterior corner. Aritenoid cartilage was only visible in 85% of cases.Ultrasound is presented as a useful auxiliary method in the study of the anatomy of the larynx, proposing the follow-up and conduct of further studies that may complement this study and its validity

Emergency Front-of-Neck Airway Rescue Via the Cricothyroid Membrane: A High-Resolution Computed Tomography Study of Airway Anatomy in Adults.

BACKGROUND: Emergency front-of-neck airway rescue is recommended in a can't intubate, can't oxygenate clinical scenario. Cannula cricothyroidotomy has been reported as having a high failure rate. Our primary aim was to estimate the angle of the trachea in relation to the horizontal axis in a simulated emergency front-of-neck airway rescue position. Our secondary aims were to estimate the optimal cannula angle of approach and evaluate the anatomical relationship of the cricothyroid membrane (CTM) to adjacent structures. We also assessed whether the CTM lies above or below the neck midpoint, a point equidistant from the suprasternal notch (SSN), and the chin surface landmarks. All measurements were compared between the male and female subjects. METHODS: Subjects having elective computed tomography of their thorax were consented to have extension of the computed tomography to include their neck. A preliminary radiation dose and risk assessment deemed the additional radiation to be of very low risk (level IIa). Subjects were positioned supinely on the computed tomography table. Standard neck extension was achieved by placing a pillow under the scapulae and a rolled towel under the neck to simulate emergency front-of-neck airway rescue positioning. RESULTS: Fifty-two subjects were included in this study: 31 men and 21 women. The mean angle of the trachea in relation to the horizontal axis was 25.5° (95% confidence interval [CI], 21.8-29.1) in men and 14.0° (95% CI, 11.5-16.5) in women. The mean minimum angles required for hypothetical cannula cricothyroidotomy for men and women were 55.2° (95% CI, 51.8-58.7) and 50.5° (95% CI, 45.4-55.6), respectively. The CTM was located lower in the neck in men compared to women. The CTM was located below the neck midpoint in 30 of 30 (100%) male subjects and 11 of 20 (55%) female subjects (P < .001). CONCLUSIONS: The trachea angulates posteriorly in a simulated emergency front-of-neck airway rescue position in supine subjects and to a greater degree in men compared to women (P < .001). The minimum angle required for hypothetical cannula cricothyroidotomy was >45° in the majority (75%) of subjects studied. A steeper cannula angle of approach may be more reliable and warrants further clinical study. If airway anatomy is indistinct and performing a vertical scalpel cricothyroidotomy, consideration should be given to performing this incision lower in the neck in men compared to women.

Optimal Arytenoid Position in Laryngeal Framework Surgery: An Anatomic Human Larynx Study.

OBJECTIVES: The purpose of this study was to better understand the effects of stitch placement on arytenoid medialization by measuring normative cricoarytenoid joint anatomy and changes in arytenoid position when varying arytenopexy stitch configuration. METHODS: This adult human larynx study was done in two parts. First, measurements of the cricoid and arytenoid cartilage anatomy relevant to cricoarytenoid joint function were made in 45 preserved larynges (26 male (M), 19 female (F)) using digital calipers. Second, the arytenoids of six fresh larynges ( three M, three F) were sutured to the cricoid using various arytenopexy-stitch placements ranging from inferior-lateral to superior-medial, and the resulting arytenoid positions were compared by measuring medial displacement of the arytenoid body and change in glottal configuration from macro still images using Image J. Paired t-tests were used to compare the results. RESULTS: Cartilage and joint facet dimensions showed differences between males (M) and females (F). Cricoid facet lengths averaged 9.3 mm (M) and 7.1 mm (F), and widths averaged 4.9 mm (M) and 4.0 mm (F). The arytenoid facet widths averaged 10.5 mm (M) and 9.7 mm (F). Average distances between cricoid facets were 11.8 mm for both males and females. Securing the arytenoid superior-medially on the cricoid facet produced more medialization (2.2 mm vs 1.0 mm, P < .001) and better glottic aperture configuration (9.5° vs 2.7°, P < .001) than securing the arytenoid inferior-laterally on the facet. CONCLUSIONS: Anatomic consistency in cricoarytenoid anatomy provides reliable surgical landmarks for ideal placement of an arytenopexy suture to optimally reposition the arytenoid cartilage. Optimal arytenoid medialization can be accurately reproduced with an arytenopexy-suture that is placed superior-medially on the cricoid facet. LEVEL OF EVIDENCE: NA Laryngoscope, 131:2540-2544, 2021.

Prospective anatomical study to determine the site of insertion of recurrent laryngeal nerve into the larynx.

OBJECTIVES: Determine whether the insertion site of the recurrent laryngeal nerve (RLN) occurs at a predictable distance from the midline trachea, to help guide safe dissection during thyroid surgery. DESIGN: Prospective clinical trial. At the inferior edge of the cricoid cartilage, we measured the distance from mildline trachea to the RLN insertion site. SETTING: Single institution. PARTICIPANTS: 50 consecutive patients undergoing thyroid surgery. MAIN OUTCOME MEASURES: Distance from midline trachea to laryngeal insertion of RLN. RESULTS: The study population included 36 women and 14 men, with 72 total nerves measured. The average distance-to-midline + standard deviation (range) of the RLN was 20.7 + 2.3 (17-26) mm in women compared to 26.3 + 2.1 (22-32) mm in men. CONCLUSION: The insertion point of the RLN into the larynx at the level of inferior border of the cricoid cartilage can be reliably predicted, to facilitate early identification of the RLN during thyroid surgery.

Estudio comparativo de laringes humanas y de cerdos: hacia un modelo de entrenamiento quirúrgico / Comparative study of human and pig larynxes: towards a surgical training model

Introducción: La laringe de cerdo doméstico tiene similitudes con la laringe humana. La capacidad elástica de las cuerdas vocales del cerdo demuestran tener la mayor similitud con la humana comparado con otros animales por lo que se ha propuesto usar las laringes de cerdo como modelo de entrenamiento quirúrgico. Objetivo: Determinar las diferencias y similitudes anatómicas e histológicas entre la laringe del cerdo y la humana. Material y método: Se realizaron mediciones por 4 observadores en 5 laringes porcinas cuyos resultados se compararon con los descritos en la literatura para las laringes humanas. Además se realizaron cortes histológicos para visualizar fibras elásticas, mucinas neutras y mucinas ácidas. Resultados: El cartílago tiroides porcino mide entre las astas superiores 37,55 ±7,30 mm, entre astas inferiores 31,33 ±3,27 mm, desde la prominencia laríngea al borde posterior 34,32 ±7,30 mm. En el cartílago cricoides, desde el borde superior-inferior en el arco anterior 7,28 ±2,21 mm, altura borde superior-inferior pared posterior 27,47 ±3,40 mm, ancho máximo pared posterior 30,99 ±4,51 mm, diámetro interior anteroposterior (borde cefálico) 30,90 ±2,12 mm, diámetro interior anteroposterior (borde caudal) 21,78 ±2,55 mm, diámetro interior derecha-izquierda (borde cefálico) 18,11 ±2,13 mm, diámetro interior derecha-izquierda (borde caudal) 21,10 ±2,40 mm. Histológicamente, la laringe de cerdo y humana presentan leves diferencias en cuanto al epitelio de cada porción de la laringe, a pesar de que el tipo de cartílago es el mismo en ambas especies. Conclusión: Si bien existen diferencias anatómicas e histológicas entre la laringe de cerdo y el humano, el modelo porcino es una alternativa útil, accesible y de bajo costo para el entrenamiento en cirugía laringotraqueal y microcirugía laríngea.

Introduction: The domestic pig larynx has similarities with the human larynx. The elastic capacity of the vocal folds of the pig has the greater similarity with the human one compared with other animals. It has been proposed to use the porcine larynx as a model for surgical training. Aim: To determine the anatomical and histological differences and similarities between the pig larynx and the human larynx. Material and method: Measurements were made by 4 observers in 5 porcine larynxes whose results were compared with those described in the literature. In addition, histological sections were performed to visualize elastic fibers, neutral mucins and acid mucins. Results: The porcine thyroid cartilage measured 37.55 ±7.30 mm between the upper horns, 31.33 ±3.27 mm between lower horns and 34.32 ±7.30 mm from the laryngeal prominence to the posterior margin. In the cricoid cartilage, from the upper-lower edge in the anterior arch 7.28 ±2.21mm, height upper-lower edge posterior wall 27.47 ±3.40 mm, maximum posterior wall width 30.99 ±4.51 mm, anteroposterior inner diameter (head margin) 30.90 ±2.12 mm, inner diameter anteroposterior (caudal edge) 21.78 ±2.55 mm, inner diameter right-left (head edge) 18.11 ±2.13 mm, inner diameter right-left (caudal edge) 21.10 ±2.40 mm. Histologically, the pig and human larynxes present slight differences in the epithelium of each portion of the larynx, despite the fact that type of cartilage is the same in both species. Conclusions: Although there are anatomical and histological differences between the pig larynx and the human larynx, the porcine model is a useful, accessible and low cost alternative for training in laryngotracheal surgery and laryngeal microsurgery.

Depth to the airway lumen at the level of the cricothyroid membrane measured by ultrasound.

BACKGROUND: Knowing the likely depth to the airway before emergency cricothyroidotomy may improve success in cases where it cannot be measured. Our aim was to measure the depth to the airway at the cricothyroid membrane by ultrasound in a large group of adult patients. METHOD: Prospective, observational study in two centres, Oxford and Gloucester. Patients presenting for a large variety of surgical operations were studied. Patients under 18 years; pregnant; critically ill; had a history of neck surgery were not included. Ultrasound examination was performed pre-operatively while participants lay supine with their head and neck extended, with light transducer pressure. We measured depth to the airway lumen in mm; age; weight; height and sex. RESULTS: In total 352 patients were studied. We found that depth to the airway lumen strongly correlated with weight (r = 0.855, P < 0.001) and to a lesser extent body mass index (r = 0.781, P < 0.001). Statistical analysis produced an equation to predict upper 95% CI of depth to the airway from the patient's weight: Depth to the airway lumen in mm = (0.13 × weight in kg) + 0.86. CONCLUSIONS: If ultrasound measurement is not possible before emergency cricothyroidotomy, the clinician could use our results to predict the depth to the airway by using the patient's weight. If the upper 95% CI were used as the depth of incision, it would enter the airway in 39 out of 40 patients of that weight, without damage to posterior structures in those with a shallower airway.

The effect of cricoid and paralaryngeal force on upper oesophageal occlusion during induction of anaesthesia: a randomised, crossover study.

The aim of this study was to evaluate the effectiveness of cricoid and paralaryngeal force for oesophageal entrance occlusion during induction of anaesthesia. Seventy-four patients were included in this randomised, crossover study. The relative position of the glottis and outer anteroposterior diameter of the upper oesophageal entrance were assessed at baseline, after the application of 30 N cricoid and paralaryngeal force, and after induction of anaesthesia. The occlusion rate of the oesophageal entrance with cricoid and paralaryngeal force was assessed during direct laryngoscopy. The relative position of the upper oesophageal entrance to the glottis changed in 45 out of 74 patients after induction of anaesthesia and during direct laryngoscopy compared with the awake state. The application of cricoid and paralaryngeal force decreased the mean (SD) diameter of the upper oesophageal entrance to a similar degree in awake (8.5 (2.1) mm to 6.4 (1.7) mm and 6.5 (1.6) mm, respectively; p < 0.001) and anaesthetised (8.7 (2.2) mm to 6.5 (1.7) mm and (6.7 (1.9) mm, respectively; p < 0.001) states. During direct laryngoscopy, the occlusion rate of the oesophageal entrance was greater with cricoid compared with paralaryngeal force (46/74 vs. 26/74, respectively; p = 0.002). The relative position of the upper oesophageal entrance to the glottis may change after induction of anaesthesia and during direct laryngoscopy. Cricoid and paralaryngeal force both decrease the diameter of the upper oesophageal entrance in awake and anaesthetised states. Occlusion of the oesophageal entrance is achieved more frequently with cricoid force compared with paralaryngeal force during direct laryngoscopy.

Role of ultrasonography in determining the cricothyroid membrane localization in the predicted difficult airway.

BACKGROUND: The aim of this study was to investigate the success rates of ultrasound (US) and palpation methods in identifying the cricothyroid membrane (CTM), and compare the results with the gold standard method-computed tomography (CT) scan. METHODS: A total of 110 patients were included into the study. The midline was estimated by a single investigator using both the US and palpation methods from the prominence of the thyroid cartilage to the center of the sternal notch, and the distance was measured (in millimeters) between the two points: Point A (the midpoint of CTM) and Point B (the inferior process of thyroid cartilage). Furthermore, the distance between Point A and Point B was calculated using the CT images. Time taken to assess the CTM by using US and palpation methods were recorded. Moreover, difficulty in using the two methods was measured with the visual analog scale (VAS). In addition, demographic and morphometric characteristics of the patients were noted. RESULTS: The CTM was detected accurately in 50 (45.5%) patients with palpation and 82 (74.5%) with US. In the Bland-Altman analysis, a better agreement was observed with US. The time to assess CTM was shorter with US than with palpation, p<0.001. The VAS scores for the palpation and US difficulty were 5.13+-1.1 and 3.32+-0.9 (p<0.001), respectively. While an increased neck circumference and thyromental distance were found to be independent risk factors for the success rates of determining the CTM by palpation, body mass index is an independent risk factor for US. CONCLUSION: Localization of the CTM is more accurate and easier with US than palpation. Furthermore, the results gathered with US are in a closer range to CT scan.

Imaging of the age-related anatomical relationship between the innominate artery and the trachea.

PURPOSE: To measure the age-dependent changes of anatomical positions and relations between the trachea, cricoid cartilage (CC), and innominate artery (IA) in adults by computed tomography (CT). METHODS: A retrospective cohort reviewing images of 127 consecutive adult patients who underwent CT angiography (CTA) of the neck. The trachea-to-IA (T-IA) distance was measured as the minimal horizontal distance between them. The vertical distance between the CC and the IA was measured between the axial section, demonstrating the CC's inferior border to the axial section at the level of the T-IA measurement. RESULTS: Images of 125 patients (median age 53 years, range 18-89; 74 males) were reviewed. The mean T-IA distance was 2.3 ± 1.1 mm for males and 1.7 ± 0.9 mm for females (P = 0.002). The vertical C-IA distance was 44.2 ± 11.4 mm and 49.5 ± 12.5 mm for males and females, respectively (P = 0.01). Age correlated negatively with the vertical C-IA distance (P < 0.0001) and positively with the T-IA distance (P < 0.0001). The rate of IA variants was 23.2%, with no significant difference between the measurements of distances among patients with or without IA variants. CONCLUSIONS: This is the first description of the relationships between the trachea, CC, and IA distances in adults as depicted on CTA. The T-IA distance becomes larger while the T-CC distance becomes shorter with age.

Cricothyroid Approach for Emergency Access to the Airway.

Airway emergencies are life-threatening events that face providers of many different backgrounds. In cannot-intubate-cannot-ventilate situations, emergent access to the airway can be obtained through the cricothyroid membrane by cricothyroidotomy. The 3 main techniques are open, percutaneous, and needle cricothyroidotomy. To date, there is no compelling evidence demonstrating superiority of a particular approach. Ultimately, the method used for cricothyroidotomy should be based on the comfort and experience of the provider performing the procedure.

The anatomy of the pediatric airway: Has our knowledge changed in 120 years? A review of historic and recent investigations of the anatomy of the pediatric larynx.

BACKGROUND: There is disagreement regarding the anatomy of the pediatric airway, particularly regarding the shape of the cricoid cartilage and the location of the narrowest portion of the larynx. AIMS: The aim of this review is to clarify the origin and the science behind these differing views. METHODS: We undertook a review of published literature, University Libraries, and authoritative textbooks with key search words and phrases. RESULTS: In vivo observations suggest that the narrowest portion of the airway is more proximal than the cricoid cartilage. However, in vitro studies of autopsy specimens measured with rods or calipers, confirm that the nondistensible and circular or near circular cricoid outlet is the narrowest level. These anatomic studies confirmed the classic "funnel" shape of the pediatric larynx. In vivo studies are potentially misleading as the aryepiglottic, vestibular, and true vocal folds are in constant motion with respiration. These studies also do not consider the effects of normal sleep, inhalation agents, and comorbidities such as adenoid or tonsil hypertrophy that cause some degree of pharyngeal collapse and alter the normal movement of the laryngeal tissues. Thus, the radiologic studies suggesting that the narrowest portion of the airway is not the cricoid cartilage may be the result of an artifact depending upon which phase of respiration was imaged. CONCLUSION: In vivo studies do not take into account the motion of the highly pliable laryngeal upper airway structures (aryepiglottic, vestibular, and vocal folds). Maximal abduction of these structures with tracheal tubes or bronchoscopes always demonstrates a larger opening of the glottis compared to the outlet of the cricoid ring. Injury to the larynx depends upon ease of tracheal tube or endoscope passage past the cricoid cartilage and not passage through the readily distensible more proximal structures. The infant larynx is funnel shaped with the narrowest portion the circular or near circular cricoid cartilage confirmed by multiple in vitro autopsy specimens carried out over the past century.

Radiographic Evaluation of the Reliability of Neck Anatomic Structures as Anterior Cervical Surgical Landmarks.

BACKGROUND: Accurate location of the skin incision is helpful to decrease the technical difficulty and save the operative time in anterior cervical spine surgery. Spine surgeons usually use the traditional neck anatomic structures (the hyoid bone, thyroid cartilage, and cricoid cartilage) as landmarks during the surgery. However, the reliability of these landmarks has not been validated in actual practice. OBJECTIVE: To find out which landmark is the most accurate for identifying the cervical levels in anterior cervical spine surgery. METHODS: The lateral flexion and extension radiographs of cervical spine in standing position from 30 consecutive patients from January 2015 to February 2015 were obtained. The cervical vertebral bodies from C2 to C7 were divided equally into 2 segments. The cervical segments corresponding to each of the surface landmarks were recorded on the flexion and extension radiographs, respectively, and the displacement of corresponding cervical segments from the flexion to extension radiographs for each landmark was calculated. RESULTS: Based on the measurements, the main corresponding cervical levels for the mandibular angle were C2 on both of the flexion and extension films, for the hyoid bone were the C3-C4 interspace on flexion film and C3 on extension film, for the thyroid cartilage C5 on both of flexion and extension films, and for the cricoid cartilage C6 on flexion film and C5-C6 interspace on extension film, respectively. The ratios of displacement within 2 segments from flexion to extension were 83.3% (25/30) for mandibular angle, 56.7% (17/30) for hyoid bone, 66.7% (20/30) for thyroid cartilage, and 56.7% (17/30) for cricoid cartilage, respectively. The mean displacement from flexion to extension films were significantly less than 2 cervical segments for the mandibular angle but greater than 2 segments for the other landmarks. Significant differences were found between mandibular angle and the other 3 landmarks for the displacement from flexion to extension. CONCLUSIONS: The angle of mandible was found to be the most accurate landmark for identifying the cervical level, which corresponded to C2 and C2-C3 disc space. The hyoid bone, thyroid cartilage, and cricoid cartilage were not reliable to predict the cervical levels.

Difficulty Inserting Cuffed Endotracheal Tubes in a Child: A Case Report.

We experienced difficulty inserting cuffed inner diameter (ID) 4.5- and 5.0-mm endotracheal tubes (ETTs) in a 5-year-old boy. Postoperative ultrasound investigations showed that the internal transverse width of the cricoid cartilage was 8.0 mm. The maximum outer diameter (OD) of the deflated cuff portion of the cuffed ID 4.5- and 5.0-mm ETTs was 8.5 and 9.6 mm, respectively. The OD of an uncuffed ID 5.5-mm ETT was 7.6 mm; this tube passed the cricoid cartilage. Hence, the transverse width of the cricoid cartilage and ETT diameter including cuff folds should be considered when selecting cuffed ETTs.

The Fast and Easy Way for Double-Lumen Tube Intubation: Individual Angle-Modification.

UNLABELLED: To find the faster and easier way than the existing intubating technique for double-lumen tube, we modified the angle of double-lumen tube according to an individual's upper airway anatomy and compared the time needed and the number of attempts for successful intubation between individually angle-modified and non-modified double-lumen tubes. Adult patients undergoing elective thoracic surgery were randomly allocated in either non-angle-modified (Group N, n = 54) or angle-modified (Group M, n = 54) groups. During mask ventilation in the sniffing position, angle-modification was performed in Group M as follows: the distal tip of the tube was placed at the level of the cricoid cartilage and the shaft was bent at the intersection of the oral and pharyngeal axes estimated from the patient's surface anatomy. The time needed and the number of attempts for successful intubation and Cormack and Lehane (C-L) grade were recorded. Overall median intubation time (sec) was significantly shorter in Group M than in Group N [10.2 vs. 15.1, P<0.001]. In addition, Group M showed the shorter median intubation time (sec) in C-L grades I-III [8.2 vs. 11.1 in C-L grade I, (P = 0.003), 10.3 vs. 15.3 in II, (P = 0.001), and 11.8 vs. 27.9 in III, (P<0.001), respectively]. Moreover, all intubation was successfully performed at the first attempt in patients with C-L grades I-III in Group M (P = 0.027). Our study showed an individual angle-modification would be useful for the fast and easy intubation of double-lumen tube in patients with C-L grades I-III. TRIAL REGISTRATION: ClinicalTrials.gov NCT02190032.

Cricothyroid Articulation in Elderly Japanese With Special Reference to Morphology of the Synovial and Capsular Tissues.

OBJECTIVE: The present study aimed to clarify individual variations in the cricothyroid joint (CT joint). METHODS: Using 30 specimens of the CT joint obtained from elderly donated cadavers, we examined the composite fibers of the capsular ligament as well as the morphology of the synovial tissue. RESULTS: The capsular ligament consistently contained abundant thick elastic fiber bundles on the anterior side of the joint (anterior band) and an elastic fiber-made mesh on the posterior side (posterior mesh). The synovial membrane, lined by synovial macrophages, was usually restricted to the recesses in the medial or inferior end of the joint cavity. Without the synovial lining, elastic fibers of the capsular ligament were subsequently detached, dispersed, and exposed to the joint cavity. We also observed a folded and thickened synovial membrane and a hypertrophic protrusion of the capsular ligament. In six specimens, the joint cavity was obliterated by debris of synovial folds and elastic fiber-rich tissues continuous with the usual capsular ligament. Notably, with the exception of two specimens, we did not find lymphocyte infiltration in the degenerative synovial tissue. DISCUSSION: We considered the CT joint degeneration to be a specific, silent form of osteoarthritis from the absence of lymphocyte infiltration. For high-pitched phonation, the elderly CT joint seemed to maintain its anterior gliding and rotation with the aid of elastic fiber-rich tissues compensating for the loss of congruity between the joint cartilage surfaces. Conversely, however, high-pitched phonation may accelerate obliteration of the joint.

A Tunneled Subcricoid Approach for Anterior Cervical Spine Reoperation: Technical and Safety Results.

OBJECTIVE: Anterior cervical spine decompression and fusion are common neurosurgical operations. Reoperation of the anterior cervical spine is associated with increased morbidity. The authors describe a novel subcricoid approach to protect the recurrent laryngeal nerve in a cuff of tissue while facilitating surgical access to the anterior cervical spine. METHODS: Single institution, consecutive case review of 48 patients undergoing reoperation in the anterior cervical region including the level of C5 and below. Univariable and multivariable regression analysis was used to determine predictors of postoperative morbidity. RESULTS: No intraoperative complications were reported. Estimated blood loss for the approach was 13.6 ± 3.1 mL. Nine of 48 patients developed immediate postoperative complications, including vocal cord paresis (10.4%), moderate-to-severe dysphagia (10.4%), and neck edema requiring intubation (2.1%). No postoperative hematomas or death occurred. All complications occurred with 4 or more levels of exposure (1-3 disc levels, 0%, vs. ≥ 4 disc levels, 31%). Extension of the exposure to the upper thoracic spine was associated with odds for postoperative complications (adjusted odds ratio, 6.50; 95% confidence interval, 1.14-37.03) and prolonged hospital stay (adjusted increase 4.23 days, P < 0.01). CONCLUSION: The tunneled subcricoid approach is a relatively safe corridor to reapproach the anterior cervical spine at the level of C5 and below. However, caution must be exercised when using this approach to expose 4 or more disc levels and with extension of the exposure to the upper thoracic spine. Future comparative studies are needed to establish patient selection criteria in determining the use of this technique compared with classic approaches.

Cricoarytenoid Articulation in Elderly Japanese With Special Reference to Morphology of the Synovial Tissue.

OBJECTIVE: To clarify composite fibers and cells in the synovial tissues of the cricoarytenoid joint (CA joint). METHODS: Routine histology and immunohistrochemistry using sagittal or nearly sagittal sections obtained from 18 elderly cadaveric specimens. RESULTS: The CA joint capsule was thin and contained few elastic fibers. A limited supportive ligament, namely, a thickened fascia of the posterior cricoarytenoid muscles, was sometimes evident on the lateral aspect of the CA joint. However, even in the weaker medial aspect of the joint, no marked destruction of the synovial tissues was found. The CA joint always contained synovial folds--a short medial fold and long lateral folds--but these contained no or few macrophages, lymphocytes, and blood capillaries. In 2 exceptional specimens showing inflammatory cell infiltration in the submucosal tissue of the larynx, the macrophage-rich area extended toward the capsule and medial synovial fold. CONCLUSIONS: The lateral aspect of the CA joint was likely to be supported mechanically by the muscle-associated tissues. Strong support of the arytenoid by muscles might reduce the degree of CA joint injury with age. However, some patients with hoarseness due to mucosal inflammation of the larynx might have accompanying synovitis and subsequent cartilage injury in the CA joint.

Cricothyroid joint anatomy as a predicting factor for success of cricoid-thyroid approximation in transwomen.

OBJECTIVES/HYPOTHESIS: Cricoid-thyroid approximation (CTA) performed to elevate the vocal pitch in transwomen fails in about one-third of the patients. The purpose of this study was to test the feasibility of predicting the likelihood of success of CTA by preoperative determination of the crico-thyroid joint (CTJ) type using three-dimensional (3-D) images derived from high-resolution computer tomography (HRCT). STUDY DESIGN: Prospective cohort study of 18 transwomen who underwent CTA at our institution. METHODS: All patients had a preoperative and a postoperative HRCT of the larynx, as well as pre- and postoperative measurements of the fundamental vocal pitch (F0 ). RESULTS: Three-dimensional images showed type A CTJs in 11 patients and type B or C CTJs in seven patients (see below for the definition of these types). Cricoid-thyroid approximation raised the F0 on average by 76 Hz in patients with type A CTJs and by 45 Hz in patients with type B/C CTJs. Moreover, CTA produced a vocal fold elongation of 17% in larynges with type A joint but only of 3% in larynges with type B/C joints. CONCLUSION: Three-dimensional images allow the differentiation of type A versus type B/C CTJs but not the distinction between type B and type C CTJs. Both vocal pitch elevation and vocal fold elongation following CTA are significantly greater in patients with type A CTJs than in patients with type B/C CTJs. Based on these preliminary results, we recommend identifying the CTJ type on 3-D images and limiting CTA to patients with type A CTJs. LEVEL OF EVIDENCE: 4. Laryngoscope, 126:1380-1384, 2016.