Evaluation of neck ultrasound measurements as a difficult airway predictor: A prospective observational study.

This study aimed to investigate the relationship between cervical measurements and difficult airways using ultrasonographic measurements. American Society of Anesthesiologists grade I to III, male or female, 120 adult patients, undergoing elective surgery were enrolled in the study. The study involved measuring the distance of the trachea, cricoid cartilage, thyroid cartilage, vocal cord anterior commissure, and hyoid bone to the skin using a 10 to 13 MHz linear ultrasound probe in the transverse plane. Additionally, the length of the cricothyroid and thyrohyoid membranes, along with their distance from the skin, were measured using the probe in the sagittal plane. Subsequently, another experienced anesthesiologist conducted mask ventilation and intubation after the patient's induction of general anesthesia. Throughout this process, the patient was assessed for difficulties in mask ventilation, laryngoscopy, and intubation. 28 (23.3%) patients had a difficult airway. Analyzing the measurements associated with difficult airways, the most reliable predictor was the epiglottis midline-skin distance [AUC (area under the curve): 0.847, P < .001, cutoff: >19.9, sensitivity: 78.6%, specificity: 79.4%]. Additionally, other factors such as hyoid bone to skin distance, thyroid cartilage to skin distance, thyrohyoid membrane to skin distance, and vocal cord anterior commissure-skin distance were also identified as predictors for a difficult airway. The increase in the distance of the epiglottis midline, vocal cord anterior commissure, hyoid bone, thyrohyoid membrane, and thyroid cartilage to the skin at the level of the isthmus measured by ultrasonography is predictive of difficult airways. Based on our study outcomes, we assert that ultrasonographic evaluation can be used in the prediction of difficult airways.

Congenital crico-thyroid dysplasia: a comprehensive description.

INTRODUCTION: We describe a first case of human congenital crico-thyroid dysplasia associated to a right sided aortic arch and an aberrant subclavian artery. CASE PRESENTATION: Our patient presented with a two-weeks history of acute dyspnea, and reported hoarseness since his childhood. An urgent tracheotomy was performed, followed by direct laryngoscopy. Endoscopic examination showed a deviation of the dorsoventral axis of the larynx, with an obstructive submucosal swelling the area of the right false cord and aryepiglottic fold. Computed tomography conducted the following day confirmed the crico-thyroid dysplasia, an infected laryngocele, and the presence of a right sided aortic arch and an aberrant subclavian artery. CONCLUSION: The embryological basis of these anomalies is attributed to congenital defects of the development of the fourth and sixth pharyngeal arches. To our knowledge, the congenital crico-thyroid dysplasia has not been previously reported in human. This case underscores the importance of recognizing anatomical variations in laryngeal cartilages, understanding their embryological origins, and potential associated malformations.

The Effect of Thyroid Surgery on the Accuracy of Palpation-Based Cricothyroid Membrane Identification in Female Patients: A Prospective Observational Cohort Study.

Background and Objectives: This study examined how a history of thyroid surgery impacts the precision of cricothyroid membrane (CTM) identification through palpation (validated by ultrasound) in female patients visiting the operating room for surgeries unrelated to neck procedures. Materials and Methods: This prospective observational cohort study enrolled adult female patients undergoing elective non-neck surgery, dividing them into control (no thyroid surgery history; n = 40) and experimental (with thyroid surgery history; n = 40) groups. CTM identification was performed by palpation and confirmed via ultrasound. Results: There were no significant differences between two groups in the demographic characteristics of the patients. The success rate and accuracy of CTM identification through palpation were significantly higher in the control group compared to the experimental group (90% vs. 42.5%, respectively; p < 0.001). For female patients with a history of thyroid surgery, the sensitivity of successful CTM palpation was 42.5%, and the specificity was 10%. These figures are based on the calculated true positives (17), false positives (36), true negatives (4), and false negatives (23). Conclusions: Thyroid surgery history in female patients may hinder the accurate palpation-based identification of the CTM, suggesting a need for enhanced clinical practices and considerations during airway management training.

Prostate-Specific Membrane Antigen PET/CT Detection of Prostate Cancer Metastasis to Thyroid and Cricoid Cartilages.

ABSTRACT: Prostate-specific membrane antigen (PSMA) PET/CT has revolutionized the imaging of prostate cancer. Historically, prostate cancer metastasis to thyroid and cricoid cartilages was thought to be exceedingly rare, with only a few reported cases in the literature. Prostate cancer metastasis to the laryngeal cartilages was detected in 4 of 221 patients who underwent imaging with 18 F-PSMA (Pylarify) or 68 Ga-PSMA (Illuccix) PET/CT for initial staging of high-risk prostate cancer or restaging evaluation in the setting of biochemical recurrence from April 2022 through October 2023. The increased sensitivity and specificity of PSMA PET/CT allow for the detection of previously occult metastatic disease.

Palpation Versus Ultrasonography for Identifying the Cricothyroid Membrane in Case of a Laterally Deviated Larynx: A Randomized Trial.

BACKGROUND: Large neck circumference and displacement of the trachea due to pathology increase the risk of failed identification of the cricothyroid membrane and cricothyroidotomy. We investigated whether ultrasound aids in the successful identification of the cricothyroid membrane in a model of an obese neck with midline deviation of the trachea. METHODS: We developed silicone neck models that were suitable for both palpation and ultrasonography and where the trachea deviated laterally from the midline to either side. After reading a book chapter and participating in a 25-minute lecture and a 15- to 23-minute hands-on demonstration and rehearsal of ultrasonography for identification of the cricothyroid membrane, anesthesiologists and anesthesiology residents randomly performed identification with either ultrasound or palpation on 1 of 2 neck models. RESULTS: We included 57 participants, of whom 29 and 28 were randomized to palpation and ultrasound, respectively. Correct identification of the cricothyroid membrane was achieved by 21 (75.0%) vs 1 (3.5%) of participants in the ultrasound versus palpation groups (risk ratio [RR], 21.8 [95% confidence interval {CI}, 3.1-151.0]). The tracheal midline position in the sagittal plane was identified correctly by 24 (85.7%) vs 16 (55.2%) of participants in the ultrasound versus palpation groups (RR, 1.6 [95% CI, 1.1-2.2]). CONCLUSIONS: Identification of the cricothyroid membrane in a model of an obese neck with midline deviation of the trachea was more often successful with ultrasound compared to palpation. Our study supports the potential use of ultrasound before induction of anesthesia and airway management in this group of patients, and it may even be applied in emergency situations when ultrasound is readily available. Further studies in human subjects should be conducted.

Determination of the Cricothyroid Membrane Height by Age and Sex and Optimal Tracheal Tube Size.

OBJECTIVES: The primary aim of this study was to determine the average cricothyroid membrane (CTM) height in healthy volunteers, and the secondary aim was to determine the hypothetical success rate for emergency cricothyrotomy with a tracheal tube with an 8.0 mm outer diameter. METHODS: This study included healthy volunteers aged 18 years and older. The participants' clinical characteristics were recorded, and their CTM height was measured using ultrasound, with their necks placed sequentially in the neutral and extension positions. The relationship between the CTM height and sex, age, height, weight, body mass index, and sternomental distance was evaluated using linear regression analysis. An equation that could estimate the height of the CTM was obtained with the parameters found significant in this analysis. RESULTS: Of the 340 participants, 208 (61.2%) were male. The mean (SD) height of the CTM in the extension position was 9.60 (1.54) mm, and it was significantly shorter in the women than in the men (8.72 [1.19] mm vs. 10.16 [1.48] mm, p < 0.001). Among the participants of short stature, the CTM was significantly shorter, regardless of sex. The hypothetical success rate for emergency cricothyrotomy was 93.3% for the males and 73.5% for the females. The equation for estimating the height of the CTM in the extension position was determined as -4.36 + 5.27 × height (m) + 0.32 × sternomental distance (cm). CONCLUSIONS: Since the CTM height may differ according to age, sex, and height, cricothyrotomy sets should be available in various outer diameters. LEVEL OF EVIDENCE: NA Laryngoscope, 134:1825-1830, 2024.

The Effect of an Increasing Subglottal Stenosis Constriction That Extends From the Vocal Folds to the Inferior Border of the Cricoid Cartilage.

Acquired subglottal stenosis is an unpredicted complication that can occur in some patients who have undergone prolonged endotracheal intubation. It is a narrowing of the airway at the level of the cricoid cartilage that can restrict airflow and cause breathing difficulty. Stenosis is typically treated with endoscopic airway dilation, with some patients experiencing multiple recurrences. The study highlights the potential of computational fluid dynamics as a noninvasive method for monitoring subglottic stenosis, which can aid in early diagnosis and surgical planning. An anatomically accurate human laryngeal airway model was constructed from computerized tomography (CT) scans. The subglottis cross-sectional area was narrowed systematically using ≈10% decrements. A quadratic profile was used to interpolate the transformation of the airway geometry from its modified shape to the baseline geometry. The numerical results were validated by static pressure measurements conducted in a physical model. The results show that airway resistance follows a squared ratio that is inversely proportional to the size of the subglottal opening (R∝A-2). The study found that critical constriction occurs in the subglottal region at 70% stenosis (upper end of grade 2). Moreover, removing airway tissue below 40% stenosis during surgical intervention does not significantly decrease airway resistance.

Computed tomographic laryngotracheal dimensions in adult domestic rabbits (Oryctolagus cuniculus) are positively associated with body weight and the laryngotracheal lumen is narrowest at the level of the thyroid cartilage.

OBJECTIVE: This retrospective study aimed to measure rabbit laryngotracheal dimensions at different locations on computed tomography (CT), assess the relationship of these measurements with rabbit body weight, determine the most common narrowest measurement and assess its relationship with endotracheal tube (ETT) size and body weight. ANIMALS: 66 adult domestic rabbits (Oryctolagus cuniculus) of different breeds and body weights. PROCEDURES: CT laryngotracheal luminal height, width, and cross-sectional area measurements were made at the rostral thyroid cartilage at the level of the arytenoids, caudal thyroid cartilage/rostral cricoid cartilage, caudal cricoid cartilage/cranial trachea, and trachea at the level of the fifth cervical vertebra. RESULTS: The data for every measurement of luminal airway dimensions revealed robust positive associations with body weight (P < .001). The narrowest laryngotracheal measurement was the width at the level of the caudal thyroid cartilage/rostral cricoid cartilage, and the smallest cross-sectional area was at the rostral thyroid cartilage at the level of the arytenoids. There was a strong association between body weight and the likelihood of appropriate ETT fit. To have at least an 80% chance of appropriate ETT fit with a 2.0, 2.5, and 3.0 mm ETT, the rabbits' weight predicted by the model (lower 95% confidence limit) were at least 2.99 (2.72) kg, 5.24 (4.65) kg, and 5.80 (5.21) kg, respectively. CLINICAL RELEVANCE: The laryngotracheal lumen was narrowest at the level of the caudal thyroid cartilage in rabbits, which indicates this location may be the limiting factor in determining ETT size in rabbits.

Anatomic Characteristics of the Adolescent Cricothyroid Membrane on Computed Tomography Scans.

BACKGROUND: The cricothyroid membrane (CTM) is the most important anatomic structure when performing emergency front-of-neck access (FONA) procedures. Adolescence is a period of rapid morphologic change in laryngeal structures, including the CTM. We hypothesized that the adolescent CTM would be sufficiently different from pediatric or adult anatomy to merit special consideration in FONA. OBJECTIVE: The aim of the study was to define the procedurally relevant CTM anatomy in an adolescent population. METHODS: This was a retrospective, multicenter cohort study composed of patients who underwent a diagnostic computed tomography scan during routine clinical care. Inclusion criteria were ages 16 to 19 years and a computed tomography of the neck with or without contrast. The primary outcome was CTM height measured in the midsagittal plane using electronic calipers. RESULTS: One hundred thirty-four imaging studies met inclusion criteria. The average CTM height was strongly associated with age and ranged between 5.4 and 6.2 mm in male adolescents and 4.6 and 5.8 mm in female adolescents. We predicted that standard cuffed endotracheal and tracheostomy tubes recommended for FONA procedures (5.0- and 6.0-mm devices) could potentially fail for most patients in our cohort. CONCLUSIONS: The adolescent CTM is smaller than previously recognized. We recommend having a variety of equipment sizes readily available at any site where airway management in adolescents may occur.

Effectiveness of Cricoid and Paratracheal Pressures in Occluding the Upper Esophagus Through Induction of Anesthesia and Videolaryngoscopy: A Randomized, Crossover Study.

BACKGROUND: Maneuvers for preventing passive regurgitation of gastric contents are applied to effectively occlude the esophagus throughout rapid sequence induction and intubation. The aim of this randomized, crossover study was to investigate the effectiveness of cricoid and paratracheal pressures in occluding the esophagus through induction of anesthesia and videolaryngoscopy. METHODS: After the induction of anesthesia in 40 adult patients, the location of the esophageal entrance relative to the glottis and location of the upper esophagus relative to the trachea at the low paratracheal region were assessed using an ultrasonography, and the outer diameter of the esophagus was measured on ultrasound before and during application of cricoid and paratracheal pressures of 30 N. Then, videolaryngoscopy was performed with the application of each pressure. During videolaryngoscopy, location of the esophageal entrance relative to the glottis under cricoid pressure was examined on the screen of videolaryngoscope, and the upper esophagus under paratracheal pressure was evaluated using ultrasound. The occlusion rate of the esophagus, and the best laryngeal view using the percentage of glottic opening scoring system were also assessed during videolaryngsocopy. Esophageal occlusion under each pressure was determined by inserting an esophageal stethoscope into the esophagus. If the esophageal stethoscope could not be advanced into the esophagus under the application of each pressure, the esophagus was regarded to be occluded. RESULTS: During videolaryngoscopy, esophagus was occluded in 40 of 40 (100%) patients with cricoid pressure and 23 of 40 (58%) patients with paratracheal pressure (difference, 42%; 95% confidence interval, 26-58; P < .001). Both cricoid and paratracheal pressures significantly decreased the diameter of the esophagus compared to no intervention in the anesthetized paralyzed state ( P < .001, respectively). Ultrasound revealed that the compressed esophagus by paratracheal pressure in the anesthetized paralyzed state was partially released during videolaryngoscopy in 17 of 40 patients, in whom esophageal occlusion was unsuccessful. The best laryngeal view was not significantly different among the no intervention, cricoid pressure, and paratracheal pressure (77 [29] % vs 79 [30] % vs 76 [31] %, respectively; P = .064). CONCLUSIONS: The occlusion of the upper esophagus defined by inability to pass an esophageal stethoscope was more effective with cricoid pressure than with paratracheal pressure during videolaryngoscopy, although both cricoid and paratracheal pressures reduced the diameter of the esophagus on ultrasound in an anesthetized paralyzed state.

Performance time of anesthesiology trainees for cricothyroid membrane identification and characteristics of cricothyroid membrane in pediatric patients using ultrasonography.

BACKGROUND: Identifying the cricothyroid membrane is an essential technical skill for front-of-neck access procedures. AIMS: This study evaluated the usefulness of cricothyroid membrane identification in pediatric patients using ultrasonography by anesthesiology trainees without experience in airway ultrasound and collected anatomical data on the cricothyroid membrane and its surrounding airway structures in children. METHODS: This prospective observational study included children aged <18 years scheduled to undergo general anesthesia and anesthesiology trainees who identified the cricothyroid membrane in five sequential anesthetized patients using ultrasonography. A pediatric anesthesiologist confirmed the accuracy of the identified cricothyroid membrane and recorded the performance time. The primary aims were the cricothyroid membrane identification success rate and performance time. The secondary aims were the characterization of the cricothyroid membrane and its surrounding structures. RESULTS: Overall, 150 pediatric patients and 30 anesthesiology trainees were analyzed. The cricothyroid membrane identification success rate using ultrasonography was 100% in all the attempts using a transverse approach. The mean (standard deviation) performance time was 27.2 (18.6) s and 31.0 (23.8) s using the transverse and longitudinal approaches, respectively. The performance time decreased by 3.1 (p = .003, 95% confidence interval [CI] = -5.1--1.0) and 5.2 (p = .007, 95% CI = -8.9--1.4) seconds per increase in number of attempts with the transverse and longitudinal approaches, respectively. The cricothyroid membrane length was mostly correlated with the patients' height (r = .75, p < .001), and the blood vessels surrounding the cricothyroid membrane were observed in 95.9% of the patients. CONCLUSIONS: Anesthesiology trainees without experience in airway ultrasound successfully identified the cricothyroid membrane in pediatric patients using ultrasonography after a brief training period. Further research is required as the identification of a structure does not predict the success of the actual procedure, particularly if done in an emergency situation.

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.

Age related changes in thyroid and cricoid cartilages: An autopsy based radiological analysis.

Forensic age estimation is an invaluable aspect of human identification. Out of these many means of age estimation, few regions with untapped potential for assistance in forensic age estimation are the age-related changes in the laryngeal cartilages. As the age advances, the thyroid and cricoid cartilages undergo gradual calcification in an individual. These age-related changes can be visualized in both the living and the dead using conventional radiography and can be objectively assessed. The objective of the present study was to evaluate the age-related changes in the laryngeal cartilages and the results may be utilized for age estimation in forensic examinations. The laryngeal cartilages were carefully dissected using standard procedures from 75 cadavers of age ranging from 17 to 65 years, during the post-mortem examination. The laryngeal cartilages were radiographed and replaced in the body cavity before culminating the post-mortem examination. The calcification of both cartilages was studied by using the standard grading method. Calcification scores of individual regions of both the laryngeal cartilages show a statistically significant positive correlation with chronological age (P < 0.05). Regression models derived from the degree of calcification of thyroid and cricoid cartilages showed standard error of estimates that ranged between 9.90 and 11.07 years. Considering the standard error of estimates of the regression analysis, the present study concludes that these regression models can be used in adjunct with other methods of age estimation such as the skeletal and dental age or when such methods are not viable as in cases of charred or mutilated remains.

Accuracy of cricothyroid membrane identification using ultrasound and palpation techniques in obese obstetric patients: an observational study.

BACKGROUND: During performance of emergency front of neck access, the final step in management algorithms for the 'can't intubate, can't oxygenate' scenario, accurate identification of the cricothyroid membrane is crucial. Accurate identification using palpation techniques is low, with highest failure rates occurring in obese females. METHODS: This prospective observational study recruited 28 obese obstetric patients. The cricothyroid membrane was identified using ultrasound, marked with an ultraviolet pen and covered with a dressing. The candidate was asked to perform cricothyroid membrane identification using landmark technique (group L) followed by ultrasound (group U). The primary outcome was the distance between the actual and estimated cricothyroid membrane midpoint. Secondary outcomes were the proportion of accurate assessments, time taken, and subjective ease of identification using a visual analogue score. RESULTS: Distance from the cricothyroid membrane midpoint was shorter in group U than Group L (2.5 mm vs 5.5 mm, P=0.002). The proportion of correctly identified cricothyroid membranes was greater in group U than group L (71% vs 39%, P=0.015). Time required for identification was shorter in group L than group U (16.9 s vs 23.5 s, P=0.001). Visual analogue scores for ease of identification were lower in group U than group L (2.4 cm vs 4.2 cm, P=0.013). CONCLUSIONS: Ultrasound-guided cricothyroid membrane localisation was significantly more accurate but slower than the landmark technique in obese obstetric patients. As such, we recommend the use of pre-procedural identification of the cricothyroid membrane in this patient population and formal training of anaesthetists in airway ultrasound.

Dimensional compatibility of currently available equipment for cricothyroidotomy and adult airway anatomy: an in vitro analysis.

BACKGROUND: There are scant data on the dimensional compatibility of cricothyroidotomy equipment and related airway anatomy. We compared the dimensional design of devices for cricothyroidotomy with anatomical airway data for adult patients. METHODS: For all available cricothyroidotomy equipment the outer diameter was recorded from manufacturer information or, if not available, measured using a sliding calliper. Outer diameters were compared with recently published mean (standard deviation [sd]) values for the height of the cricothyroid membrane obtained from computed tomography, separately for males (7.9 [2.2] mm) and for females (5.9 [1.7] mm). RESULTS: Twenty-one cricothyroidotomy sets (10 uncuffed, 11 cuffed) with 15 differently designed devices were included. Inner diameters of the tubes ranged from 3.5 to 6.0 mm and outer diameters from 5.0 to 11.7 mm. The outer diameter of the 15 different tubes was found to be greater than the mean membrane height of the adult male cricothyroid membrane in eight devices and greater than the mean membrane height for female adults in 10 devices. Considering the lower range of cricothyroid membrane height, 12 tube outer diameters would be too large for male adults and all 15 for female adults in this range. CONCLUSION: The outer diameter of many devices currently marketed for cricothyroidotomy are oversized for adult airway anatomy, particularly for females. For emergency front-of-neck access through the cricothyroid membrane, anatomical data suggest that cricothyroidotomy devices with outer tube diameters of <7 mm for male and <6 mm for female adult patients should be preferred.

Effect of Paratracheal Pressure on the Glottic View During Direct Laryngoscopy: A Randomized Double-Blind, Noninferiority Trial.

BACKGROUND: Cricoid pressure has been used as a component of the rapid sequence induction and intubation technique. However, concerns have been raised regarding the effectiveness and safety of cricoid pressure. Paratracheal pressure, a potential alternative to cricoid pressure to prevent regurgitation of gastric contents or aspiration, has been studied to be more effective to cricoid pressure in preventing gastric insufflation during positive pressure ventilation. However, to adopt paratracheal compression into our practice, adverse effects including its effect on the glottic view during direct laryngoscopy should be studied. We conducted a randomized, double-blind, noninferiority trial comparing paratracheal and cricoid pressures for any adverse effects on the view during direct laryngoscopy, together with other secondary outcome measures. METHODS: In total, 140 adult patients undergoing general anesthesia randomly received paratracheal pressure (paratracheal group) or cricoid pressure (cricoid group) during anesthesia induction. The primary end point was the incidence of deteriorated laryngoscopic view, evaluated by modified Cormack-Lehane grade with a predefined noninferiority margin of 15%. Secondary end points included percentage of glottic opening score, ease of mask ventilation, change in ventilation volume and peak inspiratory pressure during mechanical mask ventilation, ease of tracheal intubation, and resistance encountered while advancing the tube into the glottis. The position of the esophagus was assessed by ultrasound in both groups to determine whether pressure applied to the respective area would be likely to result in esophageal compression. All secondary outcomes were tested for superiority, except percentage of glottic opening score, which was tested for noninferiority. RESULTS: Paratracheal pressure was noninferior to cricoid pressure regarding the incidence of deterioration of modified Cormack-Lehane grade (0% vs 2.9%; absolute risk difference, -2.9%; 95% confidence interval, -9.9 to 2.6, P <.0001). Mask ventilation, measured on an ordinal scale, was found to be easier (ie, more likely to have a lower score) with paratracheal pressure than with cricoid pressure (OR, 0.41; 95% confidence interval, 0.21-0.79; P = .008). The increase in peak inspiratory pressure was significantly less in the paratracheal group than in the cricoid group during mechanical mask ventilation (median [min, max], 0 [-1, 1] vs 0 [-1, 23]; P = .001). The differences in other secondary outcomes were nonsignificant between the groups. The anatomical position of the esophagus was more suitable for compression in the paratracheal region, compared to the cricoid cartilage region. CONCLUSIONS: Paratracheal pressure was noninferior to cricoid pressure with respect to the effect on glottic view during direct laryngoscopy.

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.

Functional optimisation in chondrosarcoma of the subglottis: a novel surgical approach.

Chondrosarcoma of the larynx is rare accounting for approximately 1% of laryngeal cancers; clear cell subtype is a rare variant. Given the low risk of occult nodal disease, they present a unique opportunity to maximise tissue preservation in order to optimise both recovery and long-term functional outcomes. We present a case of laryngeal clear cell chondrosarcoma causing critical airway obstruction. An emergency tracheostomy was performed and mapping biopsies were taken. The tumour originated from the cricoid and extended into both arytenoid superstructures precluding cricotracheal resection. A modified narrow-field laryngectomy was performed, preserving all pharyngeal mucosa and neurovascularly intact infrahyoids. Organ preservation surgery is preferred in the management of laryngeal chondrosarcoma. If laryngectomy is required, the surgeon must ensure that all uninvolved, functional tissue is preserved carefully to improve swallow and voice outcomes postoperatively. We describe a novel technique used to achieve this outcome.