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.

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.

Angles of Needle Insertion for True Vocal Fold Access Via the Thyrohyoid and Cricothyroid Membranes of the Larynx.

OBJECTIVE: This study aims to provide an analysis of the cricothyroid and thyrohyoid membrane approaches for laryngeal injections in cadaveric vocal cords. The primary objective is to determine the optimal techniques, needle trajectories, and anatomical landmarks for accessing different regions of the vocal cords percutaneously. MATERIALS AND METHODS: The study was conducted on 23 adult cadavers, consisting of 8 females and 15 males. The cadaveric larynges were mounted vertically to ensure proper anatomical positioning. Both the cricothyroid and thyrohyoid membrane approaches were utilized for reaching the vocal cords. Measurements were taken for needle trajectories, angles, and distances to determine the optimal approach for accessing the anterior, middle, and posterior thirds of the vocal cord. RESULTS: Through the thyrohyoid membrane approach, the anterior, middle, and posterior thirds of the vocal cords can be accessed with the optimal needle insertion coronal angles of 15.46 ± 7.86°, 16.52 ± 7.15° and 18.29 ± 14.46°, and sagittal angles of 126.01 ± 9.65°, 116.67 ± 8.04° and 111.02 ± 8.86° respectively at a lateral distance of 1.92 ± 1.62 mm from the midline and 8.48 ± 2.73 mm below the vertical line. From the cricothyroid membrane approach, optimal coronal and sagittal insertion angles of the anterior, middle, and posterior thirds of the vocal cord were respectively: 158.95 ± 9.3°, 156.09 ± 11.59°, 152.4 ± 14.46°, 11.5 ± 7.77°, 21.83 ± 12.47° and 32.91 ± 12.59°. CONCLUSION: This analysis of the cricothyroid and thyrohyoid membrane approaches in cadaveric larynges provides valuable insights for clinicians and researchers in the field of laryngology. The findings serve as a reference for optimizing laryngeal injection techniques, enhancing patient outcomes, and minimizing complications.

[Research Progress in Adjacent Anatomical Structure and Location of Cricothyroid Membrane].

Cricothyroid membrane puncture and incision,the key techniques to save the lives of the patients in the Can't Intubate,Can't Oxygenate (CICO) emergency,need to be mastered by all the airway management staff.However,the decision to carry out cricothyroid membrane puncture or incision is often delayed due to the unfamiliarity with the adjacent anatomical structure of the cricothyroid membrane and the inability to accurately locate the cricothyroid membrane.As a result,serious complications and rescue failure occur.Therefore,airway management staff should be familiar with the adjacent structure and positioning methods of the cricothyroid membrane,so as to improve the success rate of emergency airway rescue,reduce complications,and protect the airway and life safety of the patients.

The Feasibility Study of Intraoperative RLN Monitoring Using Cricothyroid Membrane-Inserted Needle Electrodes During Thyroid Surgery.

OBJECTIVE: This study evaluated the feasibility, stability, safety, and economy of cricothyroid membrane (CM)-inserted needle electrodes for recurrent laryngeal nerve monitoring. STUDY DESIGN: Parallel and controlled study. SETTING: Clinical research center for thyroid diseases of Shaanxi province. METHODS: A total of 64 patients in the needle electrodes group (104 recurrent laryngeal nerves [RLNs]) and 44 patients in the endotracheal tube (ETT)-based electrodes group (80 RLNs) underwent monitored thyroidectomy. The evoked electromyography (EMG) signals detected by the 2 electrodes were recorded and analyzed. The changes in EMG during Berry's ligament traction and tracheal displacement were compared. All patients underwent preoperative and postoperative laryngoscopy within 1 week. RESULTS: Both electrodes successfully recorded typical evoked laryngeal EMG waveforms from RLNs. The needle electrodes recorded relatively higher amplitudes and similar latencies compared to ETT-based electrodes. The evoked EMG signals attributed to needle electrodes could accurately predict the function of RLNs with 100% sensitivity and specificity. The reduction in the recorded amplitudes attributed to needle electrodes was higher than that observed with ETT-based electrodes during Berry's ligament traction or trachea displacement, whereas a similar increase in the latencies was recorded in the 2 groups. Particularly, Berry's ligament traction was more likely to lead to EMG amplitude reduction and latency prolongation. The needle electrodes group recorded 2 cases of minor bleeding on the CM. The needle electrodes were more cost-effective than ETT-based electrodes. CONCLUSION: The CM-inserted needle electrodes are feasible, stable, safe, and economical for RLN monitoring, and they provide an alternative novel intraoperative neural monitoring format for thyroid surgeons.

Equivalence of the top-down manoeuvre and bottom-up manoeuvre in speed and accuracy of identifying the cricothyroid membrane: a prospective randomised cross-over study.

BACKGROUND: Accurate identification of the cricothyroid membrane is crucial for successful cricothyrotomy; however, a manoeuvre that helps identify it both accurately and quickly remains unclear. The effectiveness of the so-called 'bottom-up manoeuvre' has never been investigated. This study aimed to examine whether the bottom-up manoeuvre is as rapid and accurate as the conventional 'top-down manoeuvre' at identifying the cricothyroid membrane. METHODS: This study was a prospective randomised cross-over trial conducted at an academic medical centre between 2018 and 2019. Fifth-year medical students participated. The students were trained in the use of either the top-down manoeuvre or the bottom-up manoeuvre first. Each student subsequently performed the technique once on a volunteer. The students were then taught and practiced the other manoeuvre as well. The accuracy of cricothyroid membrane identification and the time taken by successful participants only were measured and compared between the manoeuvres using equivalence tests with two one-sided tests. RESULTS: A total of 102 medical students participated in this study and there was no missing data. The accuracy of identification and time required for success were similar between the top-down manoeuvre and the bottom-up manoeuvre (65.7% vs. 70.6%, taking 13.8 s [interquartile range (IQR): 9.4-17.5] vs. 15.5 s [IQR: 11.5-19.9], respectively). The success rate was statistically equivalent (rate difference, 4.9%; 90% confidence interval [CI], -5.8 to 15.6; equivalence margin, -20.0 to 20.0). The time required for success was also statistically equivalent (median difference, 1.7 s; 90% CI, -0.2 to 3.3; equivalence margin, -4.0 to 4.0). CONCLUSION: Among students first trained in both manoeuvres for identifying the cricothyroid membrane, the speed and accuracy of identification were similar between those using the bottom-up manoeuvre and those using the top-down manoeuvre.

Improving Anesthesia Providers' Needle Cricothyrotomy Success With Ultrasound-Guidance: A Cadave Quality Improvement Project.

Difficult and failed airway management remains a significant cause of anesthesia-related morbidity and mortality. Failed airway management guidelines include performing a cricothyrotomy as a final step. Correct identification of the cricothyroid membrane (CTM) is essential for safe and accurate cricothyrotomy execution. Ten certified registered nurse anesthetists were assessed for ultrasound-guided (USG) needle cricothyrotomy competency following an online and hands-on education session using a human cadaver and then assessed 60 days later, without additional education or preparation. Both knowledge and confidence improved significantly when assessed immediately after education (P < .05) and were maintained when assessed 60 days later. Overall skill performance declined slightly from post-training although the decline was not statistically significant (P = .373). Overall needle placement time and distance from the CTM improved, despite improper transducer and image orientation by most participants. A one-hour hybrid educational program can significantly improve ultrasound and cricothyrotomy knowledge and confidence for 60 days. Transducer orientation may not be a significant contributor to performing proper USG needle cricothyrotomy.

Research Progress in Adjacent Anatomical Structure and Location of Cricothyroid Membrane / 中国医学科学院学报

Cricothyroid membrane puncture and incision,the key techniques to save the lives of the patients in the Can't Intubate,Can't Oxygenate (CICO) emergency,need to be mastered by all the airway management staff.However,the decision to carry out cricothyroid membrane puncture or incision is often delayed due to the unfamiliarity with the adjacent anatomical structure of the cricothyroid membrane and the inability to accurately locate the cricothyroid membrane.As a result,serious complications and rescue failure occur.Therefore,airway management staff should be familiar with the adjacent structure and positioning methods of the cricothyroid membrane,so as to improve the success rate of emergency airway rescue,reduce complications,and protect the airway and life safety of the patients.

Role of ultrasonography in an impalpable tissue larynx model during a simulated front-of-neck access scenario: a randomized simulation study.

PURPOSE: A large vertical incision is recommended when performing front-of-neck access in patients with impalpable neck landmarks during a cannot intubate-cannot oxygenate (CICO) scenario. We investigated the impact of ultrasonography on vertical incision size of a front-of-neck access on an ultrasound-compatible impalpable porcine larynx model. METHODS: Emergency medicine and anesthesia trainees were randomized to the Ultrasound (US, n = 21) and Non-Ultrasound (NUS, n = 21) groups. Within 1 week after a teaching session on airway ultrasound and Scalpel-Bougie-Tube (SBT) technique, participants were instructed to perform cricothyroidotomy on the model during a simulated cannot intubate-cannot oxygenate scenario. The primary outcome was a vertical size incision. Secondary outcomes were procedural completion time, horizontal size incision, tissue injury severity, and correct tube placement. RESULTS: The ultrasound group performed a significantly smaller vertical incision [median (IQR), 35.0 (15, 40) vs 65.0 (52, 100) mm (95% CI) - 30.0 (- 55.1, - 4.9), p = 0.02] and took longer total time to complete the procedure [median (IQR), 200.5 (126, 267) vs 93.5 (71.0, 167.5) secs (95% CI) 91.0 (3.73, 178.3), p = 0.04]. Tissue injury severity and correct tube placement were similar between groups. CONCLUSIONS: Ultrasound-guided identification of the cricothyroid membrane significantly reduced the recommended vertical incision size with similar success rates. However, there was an increased time when performing a Scalpel-Bougie-Tube cricothyroidotomy on an impalpable porcine larynx model by physicians in training. Ultrasonography should not be used in an emergency scenario of airway rescue. Its potential use to pre-mark the cricothyroid membrane should be considered in difficult airway management of impalpable neck.

RéSUMé: OBJECTIF: Il est recommandé de pratiquer une grande incision verticale lors de l'accès à l'avant du cou chez les patients dont les repères du cou sont impalpables, dans le cadre d'un scénario d'intubation impossible à oxygéner (CICO). Nous avons étudié l'impact de l'échographie sur la taille de l'incision verticale d'un accès à la face avant du cou sur un modèle de larynx porcin impalpable compatible avec l'échographie. MéTHODES: Des stagiaires en médecine d'urgence et en anesthésie ont été répartis de manière aléatoire entre les groupes "échographie" (US, n = 21) et "non-échographie" (NUS, n = 21). Une semaine après une session d'enseignement sur l'échographie des voies aériennes et la technique Scalpel-Bougie-Tube (SBT), les participants ont reçu l'instruction de réaliser une cricothyroïdotomie sur le modèle lors d'un scénario simulé d'impossibilité d'intubation et d'oxygénation. Le résultat primaire était une incision de taille verticale. Les résultats secondaires étaient le temps de réalisation de la procédure, la taille horizontale de l'incision, la gravité de la lésion tissulaire et le placement correct du tube. RéSULTATS: Le groupe échographie a réalisé une incision verticale significativement plus petite [médiane (IQR), 35,0 (15,40) vs 65,0 (52,100) mm (IC à 95 %) -30,0 (-55,1, -4,9), p = 0,02] et a pris un temps total plus long pour terminer la procédure [médiane (IQR), 200,5 (126, 267) vs 93,5 (71,0, 167,5) secondes (IC à 95 %) 91,0 (3,73, 178,3), p = 0,04]. La gravité des lésions tissulaires et le placement correct du tube étaient similaires entre les groupes. CONCLUSIONS: L'identification échoguidée de la membrane cricothyroïdienne a réduit de manière significative la taille de l'incision verticale recommandée avec des taux de réussite similaires. Cependant, il y avait une augmentation du temps lors de la réalisation d'une cricothyroïdotomie Scalpel-Bougie-Tube sur un modèle de larynx porcin impalpable par des médecins en formation. L'échographie ne doit pas être utilisée dans un scénario d'urgence de sauvetage des voies respiratoires. Son utilisation potentielle pour pré-marquer la membrane cricothyroïdienne devrait être envisagée dans la gestion des voies aériennes difficiles du cou impalpable.

Association between Successful Palpation of the Cricothyroid Membrane and the 3-3-2 Rule for Predicting Difficult Airway in Female Patients Undergoing Non-Neck Surgery: A Prospective Observational Cohort Study.

Background: Prediction of difficult airway is important for airway management in patients undergoing surgery. The assessment of airway structures and establishment of protective airway strategies are essential to improve patient safety. However, the association between successful palpation of the cricothyroid membrane and airway predictions has not been fully elucidated in patients undergoing surgery. We investigated this in female patients undergoing non-neck surgery. Methods: A total of 68 female patients were enrolled in this prospective observational cohort study between January 2021 and June 2021 at Eunpyeong St. Mary's Hospital, College of Medicine, Catholic University of Korea, Seoul, Republic of Korea. Exclusion criteria were male patients and those with neck pathology or neck surgery. The assessment of difficult airway was performed before the induction of anesthesia and was defined by one of the following conditions: inter-incisor distance < 3 fingerbreadths, hyoid-to-mental distance < 3 fingerbreadths, and thyroid-to-hyoid distance < 2 fingerbreadths (the "3-3-2 rule"). The accuracy of palpable identification of the cricothyroid membrane was confirmed by ultrasonography (US). The patients were divided into the non-difficult airway (NDA) group (n = 30) and the difficult airway (DA) group (n = 30). Results: The two groups were comparable in terms of age, but the DA group had higher body mass index (BMI). In airway assessment, 9 patients showed inter-incisor distance < 3 fingerbreadths, 3 patients showed hyoid-to-mental distance < 3 fingerbreadths, and 24 patients showed thyroid-to-hyoid distance < 2 fingerbreadths in the DA group. The rate of successful palpation of the cricothyroid membrane was higher in the patients without than in those with difficult airway variables. Conclusions: Patients with a positive 3-3-2 rule showed a poor palpability of cricothyroid membrane.

Modified transcricothyroid electrode recording method for monitoring recurrent laryngeal nerve function during thyroidectomy / 中华内分泌外科杂志

Objective:To study the safety, validity and practicability of the modified trans-cricothyroid needle electrode method for neurmonitoring during thyroidectomy.Methods:115 patients from the Department of Thyroid Surgery in Peking University Shenzhen Hospital scheduled for thyroid surgery were recruited into the group. Two paired needle electrodes were obliquely inserted into the cricothyroid membrane from the angle between the rectus cricothyroid muscle and the inferior margin of thyroid cartilage. The function of recurrent laryngeal nerve (RLN) was localized, exposed and evaluated by standard four-step method (V1-R1-R2-V2) . The vocal cord movement was evaluated by electronic laryngoscope before and after operation, and t-test was used to compare the difference of EMG signal amplitude before and after operation.Results:A total of 130 RLN from 115 patients were recorded effective electromyographic (EMG) signals, including 12 cases of giant goiter with tracheal compression stenosis; 13 cases had repeated adjustments of the position of tracheal intubation electrode during operation, but EMG signals were not satisfactory; 15 cases were with of accidental findings during operation and requiring neurmonitoring, but tracheal intubation electrodes were not used in advance. 75 cases were volunteers. The signals of 3 RLN were lost during operation. On the second day after operation, electronic laryngoscope showed that 2 cases had normal vocal cord movement and 1 case had vocal cord paralysis and no recovery for 6 months follow-up. The EMG signals of other 127 nerves were V1/R1=1857±1718μV/2347±2323μV, V2/R2=1924±1705μV/2450±2345μV. There was no significant difference in EMG signals between pre-operation and post-operation ( t=0.31/0.35, P=0.755/0.725) . The electronic laryngoscope showed normal vocal cord movement before and after operation. During the operation, 2 patients had a little bleeding at the needle electrode insertion point, which stopped after 5 minutes of compression. No electro-acupuncture breakage, infection or local hematoma occurred. Conclusions:The modified trans-cricothyroid needle electrode method had been proved to be safe and feasible for evaluating the function of recurrent laryngeal nerve in thyroid surgery. Besides of unaffected by tracheal conditions, it has good stability, simple implantation and low cost. In thyroid surgery, it can be used as a useful supplement to endotracheal intubation electrode.

Comparison of Cricothyroid Membrane Puncture Anesthesia and Topical Anesthesia for Awake Fiberoptic Intubation: A Double-Blinded Randomized Controlled Trial.

Background: Awake fiberoptic intubation (AFOI) is commonly used for patients with a difficult airway. The purpose of this study was to evaluate the efficacy of cricothyroid membrane puncture anesthesia and topical anesthesia during AFOI. Methods: A total of 70 patients (the American Society of Anesthesiologists score I-III) with anticipated difficult airways scheduled for nonemergency surgery with AFOI were randomly slated to receive cricothyroid membrane puncture anesthesia (n = 35) or topical anesthesia (n = 35). Each group received dexmedetomidine at a dose of 1.0 µg/kg and sufentanil at a dose of 0.2 µg/kg over 10 min for conscious sedation before intubation. The endoscopy intubation, post-intubation condition, and endoscopy tolerance as scored by the anesthetists were observed. The satisfaction of the operator regarding the procedure and the satisfaction of the patient 24 h after the surgery were also recorded. We recorded the success rate of the first intubation, intubation time, and hemodynamic changes during the procedure and also the adverse events. Results: Better intubation scores, operator satisfaction, and satisfaction of the patient were observed in the cricothyroid membrane puncture anesthesia group than in the topical anesthesia group (p < 0.05). The intubation time in the cricothyroid membrane puncture anesthesia group was less than that in the topical anesthesia group (p < 0.05). There were no significant differences in the patient tolerance scores, the success rate of the first intubation, hemodynamic changes, and adverse events between both the groups. Conclusion: Compared with topical anesthesia, cricothyroid membrane puncture anesthesia provided better intubation conditions and less intubation time with greater satisfaction of the patient and operator during endoscopic intubation. Clinical Trial Registration: URL: http://www.chictr.org.cn/showproj.aspx?proj=42636, Identifier: ChiCTR 1900025820.

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.

Ecografía de vía aérea: en busca de la membrana cricotiroidea / Airway ultrasound: in search of the cricothyoid membrane

Resumen: La ecografía forma parte activa de las herramientas clínicas que tenemos en nuestro arsenal para la valoración de pacientes, y en el manejo de la vía aérea puede permitirnos localizar y marcar la membrana cricotiroidea previo al manejo de un paciente con posible vía aérea difícil (VAD). En manos adiestradas permite identificar la anatomía para poder realizar una cricotiroidotomía con rapidez y precisión en tan sólo 24.3 segundos. En este artículo se muestra una sistemática visual y de rápida localización ecográfica de la membrana cricotiroidea con tiempo estimado inferior a un minuto. Para la exploración se debe usar una sonda lineal de alta frecuencia (5-14 MHz), ya que es probablemente la más adecuada para evaluar estructuras superficiales (dentro de 0-5 cm por debajo de la superficie de la piel). La colocación del operador y del ecógrafo van a depender de la posición del paciente, así en pacientes sentados el operador se coloca detrás de éste y el ecógrafo enfrente de ambos, y en pacientes en decúbito supino el operador se coloca a la cabecera del paciente y el ecógrafo a nivel del codo derecho del mismo.

Abstract: Ultrasonography is an active part of the clinical tools that we have in our arsenal for the evaluation of patients, and in the management of the airway, it can allow us to locate and mark the cricothyroid membrane prior to the management of a patient with a possible Difficult Airway. In trained hands allows the anatomy to be identified so that a cricothyroidotomy can be performed quickly and accurately in just 24.3 seconds. In this article, we show a rapid and visual systematic ultrasound localization of the cricothyroid membrane with an estimated time less than one minute. A linear high-frequency probe (5-14 MHz) should be used for exploration, as it is probably the most suitable for evaluating surface structures (within 0-5 cm below the skin surface). The positioning of the operator and the ultrasound scanner will depend on the patient's position, so in seated patients the operator is placed behind him and the ultrasound scanner in front of both, and in patients in a supine position, the operator is placed at the bedside of the patient and the ultrasound at the level of the right elbow.

Comparison between laryngeal handshake and palpation techniques in the identification of cricothyroid membrane: a meta-analysis.

Because the use of conventional digital palpation technique for the identification of cricothyroid membrane (CTM) has been widely believed to be unreliable, the 'laryngeal handshake' technique (LH) has been introduced for CTM identification in the event of cricothyroidotomy. To provide evidence for clinical practice, this pilot meta-analysis aimed at investigating whether identification of CTM with the LH is superior to that with the palpation technique. Studies that evaluated the accuracy of CTM identification by using LH or palpation techniques (i.e., LH group vs. Palpation group) were identified from electronic databases including PubMed, Embase, Medline, google scholar, Cochrane Central Register of Controlled Trials from inception to July 5, 2020. The primary outcome was the accuracy of both techniques. Four studies published from 2018 to 2020 were considered relevant and were read in full. We found no significant difference in success rate of CTM identification [Risk Ratio (RR) 1.09, 95% CI 0.89-1.34, p = 0.41] between the two groups. These preliminary results of the current study demonstrated no significant differences in success rate between the laryngeal handshake and conventional palpation techniques in cricothyroid membrane identification.

Anatomical Study of Two Cricothyroid Approaches to the Cadaver Larynx.

OBJECTIVE: The purpose of this study was to measure the angle and depth at which the vocal folds are accessed via transcutaneous injection through two different approaches through the cricothyroid membrane. METHODS: Twenty-five cadavers preserved with formalin were studied. The larynges were bisected through the thyroid notch, and the skin and soft tissue were removed. A 27-gauge needle was inserted through the cricothyroid membrane, once from just inferior to the thyroid cartilage and once from just superior to the cricoid cartilage, and advanced to the midpoint of the musculomembranous vocal fold (determined as the halfway point from anterior commissure to vocal process), immediately lateral to the vocalis muscle without penetrating the epithelium. The angle of approach was determined after taking multiple measurements with a Castroviejo caliper. The depth of the needle was measured. RESULTS: Ten male and 15 female cadavers were studied. Their average age was 85.5 ± 12.4 years. The mean distance from midline for an injection performed with 0° of lateral angle was 5.7 ± 0.7 mm for the males, which was significantly greater than for females (4.8 ± 0.8 mm, P = 0.012). The insertion angle for the infrathyroid approach was 22.2 ± 6.9°, which was significantly different from the supracricoid angle, which was 33.0 ± 5.2° (P < 0.001). The mean insertion depth of the subthyroid approach was 11.3 ± 1.8 mm (range 8.0-15.5 mm), which was significantly less than the depth for the supracricoid approach (18.2 ± 2.4 mm, range 11.0-22.0 mm, P < 0.001.). The infrathyroid approach angle for males was 26.0 ± 8.5°, which was significantly greater than the angle for females (19.3 ± 3.4°, P = 0.016.). The supracricoid approach angle for males was 37.5 ± 2.4°, which was significantly greater than the angle for females (29.7 ± 4.1°, P < 0.001.). The insertion depth for males was 19.6 ± 1.4 mm, which was significantly greater than that for females (17.2 ± 2.6 mm, P = 0.021). CONCLUSIONS: Comparison of a supracricoid and infrathyroid approach through the cricothyroid membrane to the middle third of the vocal folds demonstrated significant differences in angle of approach. We also identified a significant difference in the angle of entry between male and female larynges in both approaches, as well as an increased depth of insertion required in males for the supracricoid approach.

Airway stent placement for direct cricothyroid membrane puncture anesthesia with airway stricture or fistula.

Context: Tracheal stent implantation with bronchoscope has become one of the main methods for the treatment of airway stenosis. Bronchoscopy is usually performed under local or general anesthesia. Aims: The aim of this study is to report our experience with direct cricothyroid membrane puncture anesthesia for airway stent placement. Materials and Methods: The medical records of 48 consecutive patients who underwent direct cricothyroid membrane puncture anesthesia for tracheal or bronchial stent placement were reviewed. The puncture site was chosen as the interspace between the thyroid cartilage and cricoid cartilage. Through the cricothyroid membrane, lidocaine was injected into the trachea to suppress the cough reflex. The airway stent was placed fluoroscopically at 48 patients at the trachea or bronchus. The success rate and complications of cricothyroid membrane puncture anesthesia were assessed. Results: Anesthesia was successfully performed in all 48 patients. Six patients needed 2-4 mL supplementary lidocaine by injection from the catheter or stent delivery system. Technical success of the stent insertion was achieved in all 48 cases. Small asymptomatic subcutaneous hemorrhage occurred at the puncture site in two patients, which disappeared 1 or 2 days after stent placement. Conclusion: Direct cricothyroid membrane puncture anesthesia for airway metal stent insertion is safe and effective.

The effect of patient positioning on ultrasound landmarking for cricothyrotomy.

PURPOSE: Our primary objective was to assess the difference in position of the ultrasound-guided landmark of the cricothyroid membrane (CTM) when performed with the supine patient positioned at different head of bed (HOB) elevations. METHODS: In this prospective observational study of patients presenting to the emergency department with non-life-threatening complaints, subjects underwent ultrasound-guided landmarking of the CTM with HOB elevation at 0°, 30°, and 90°. A linear mixed effects regression model was used to assess the change in the CTM landmark associated with head position. We used a second adjusted linear mixed effects model to assess possible confounding patient factors associated with these changes. RESULTS: One-hundred and ten patients were enrolled, with a median [interquartile range] age of 39 [29-59] yr and 51:49 female:male ratio. Head of bed elevation at 30° and 90° resulted in a cephalad change in the CTM landmark of 2.7 mm (99% confidence interval [CI], 1.7 to 3.8; P < 0.001) and 4.2 mm (99% CI, 3.2 to 5.3; P < 0.001) respectively compared with the landmark at 0°. Body mass index (BMI) was associated with a change of 4.6 mm (99% CI, 0.5 to 8.7; P = 0.004) for BMI ≥ 30 compared with < 18.5 kg·m-2 The impact of patient age on distance depended on HOB elevation, where patients > 70 yr had a change of 2.6 mm (99% CI, 0.01 to 5.1; P = 0.009) at 90° HOB elevation compared with 30°. CONCLUSION: The location of the ultrasound-identified surface landmark of the CTM moves in a cephalad direction by changing the position of the HOB from supine 0° to elevation at 30° and 90°. This may be clinically important when attempting cricothyrotomy using a percutaneous (blind) technique, particularly when CTM identification and cricothyrotomy are performed at different head elevations.

RéSUMé: OBJECTIF: Notre objectif principal était d'évaluer la différence de position de la membrane cricothyroïdienne en tant que repère échoguidé selon qu'elle est identifiée à différentes élévations de la tête du lit avec le patient en décubitus dorsal. MéTHODE: Cette étude observationnelle prospective a inclus des patients se présentant à l'urgence pour des problèmes de santé ne mettant pas leur vie en danger. Les repères échoguidés de la membrane cricothyroïdienne ont été identifiés chez ces patients en positionnant la tête de lit à 0°, 30° et 90°. Un modèle de régression linéaire à effets mixtes a été utilisé pour évaluer les modifications du repère de la membrane cricothyroïdienne associés à la position de la tête. Nous avons utilisé un deuxième modèle linéaire à effets mixtes ajustés pour évaluer les facteurs confondants potentiels liés au patient et associés à ces changements. RéSULTATS: Cent dix patients ont été recrutés, d'un âge médian [écart interquartile] de 39 [29-59] ans et avec un ratio femmes : hommes de 51 : 49. L'élévation de la tête de lit à 30° et 90° a entraîné un glissement céphalade de 2,7 mm (intervalle de confiance [IC] 99 %, 1,7 à 3,8; P < 0,001) et de 4,2 mm (IC 99 %, 3,2 à 5,3; P < 0,001) du marquage de la membrane cricothyroïdienne, respectivement, comparativement au repère identifié à un angle de 0°. L'indice de masse corporelle (IMC) était associé à un changement de 4,6 mm (IC 99 %, 0,5 à 8,7; P = 0,004) pour un IMC ≥ 30, comparativement à < 18,5 kg·m−2. L'impact de l'âge du patient sur la distance dépendait de l'élévation de la tête de lit : chez les patients > 70 ans, le changement était de 2,6 mm (IC 99 %, 0,01 à 5,1; P = 0,009) à une élévation de la tête de lit de 90° comparativement à un angle de 30°. CONCLUSION: L'emplacement du repère de surface identifié par échoguidage de la membrane cricothyroïdienne se déplace en direction céphalade lorsqu'on change la position de la tête de lit d'un décubitus dorsal à 0° à une élévation de 30° et 90°. Cela pourrait avoir une importance clinique lors d'une tentative de cricothyrotomie à l'aide d'une technique percutanée (en aveugle), particulièrement si l'identification de la membrane cricothyroïdienne et la cricothyrotomie sont réalisées à différentes élévations de la tête.