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Objective: To investigate the feasibility of dynamic computed tomography in recording and describing the spatial motion characteristics of the arytenoid cartilage., Methods: Dynamic computed tomography recorded the real-time motion trajectory of the arytenoid cartilage during inspiration and phonation. A stationary coordinate system was established with the cricoid cartilage as a reference and a motion coordinate system was established using the movement of the arytenoid cartilage. The Euler angles of the arytenoid cartilage movement were calculated by transformation of the two coordinate systems, and the spatial motion characteristics of the arytenoid cartilage were quantitatively studied., Results: Displacement of the cricoid cartilage was primarily inferior during inspiration. During phonation, the displacement was mainly superior. When the glottis closed, the superior displacement was about 5-8 mm within 0.56 s. During inspiration, the arytenoid cartilage was displaced superiorly approximately 1-2 mm each 0.56 s. The rotation angle was subtle with slight rotation around the XYZ axis, with a range of 5-10 degrees. During phonation, the displacement of the arytenoid cartilage was mainly inferior (about 4-6 mm), anterior (about 2-4 mm) and medial (about 1-2 mm). The motion of the arytenoid cartilage mainly consisted of medial rolling, and there was an alternating movement of anterior-posterior tilting. The arytenoid cartilage rolled medially (about 20-40 degrees within 0.56 s), accompanied by anterior-posterior tilting (about 15-20 degrees within 0.56 s)., Conclusion: Dynamic computed tomography recordings of arytenoid cartilage movement can be combined with Euler transformations as a tool to study the spatial characteristics of laryngeal structures during phonation., Level of Evidence: 4 Laryngoscope, 130:E646-E653, 2020., (© 2019 The American Laryngological, Rhinological and Otological Society, Inc.)

A force sensor system was developed to give real-time visual feedback on a range of force. In a prospective observational cross-section study, twenty-two anaesthesia nurses applied cricoid pressure at a target range of 30-40 Newtons for 60 seconds in three sequential steps on manikin: Group A (step 1 blinded, no sensor), Group B (step 2 blinded sensor), Group C (step 3 sensor feedback). A weighing scale was placed below the manikin. This procedure was repeated once again at least 1 week apart. The feedback system used 3 different colours to indicate the force range achieved as below target, achieve target, above target. Significantly higher proportion of target cricoid pressure was achieved with the use of sensor feedback in Group C; 85.9% (95%CI: 82.7%-88.7%) compared to when blinded from sensor in Group B; 31.3% (95%CI: 27.4-35.4%). Cricoid force achieved blind (Group B) exceeded force achieved with feedback (Group C) by a mean of 8.0 (95%CI: 5.9-10.2, p<0.0001) and 6.2 (95%CI:4.1-8.3, p< 0.0001) Newtons in round 1 and 2 respectively. Weighing scale read lower than corresponding force sensor by a mean of 8.4 Newtons (95% CI: 7.1-9.7, p<0.0001) in group B and 5.8 Newtons (95% CI: 4.5-7.1, p<0.0001) in Group C. Force sensor visual feedback system enabled application of reproducible target cricoid pressure with less variability and has potential value in clinical use. Using weighing scale to quantify and train cricoid pressure requires a review. Understanding the force applied is the first step to make cricoid pressure a safe procedure., Competing Interests: A patent was filed for the force sensor visual feedback system titled, ‘A sensing device, system and a method of manufacture’ with Hwan Ing Hee and Chiong Ling Wong as inventors. The patent publication number was WO2016/080917A1, International Publication Date 26; May 2016 International Application No.: PCT/SG2015/050465, International Filing Date 19 Nov 2015. There are no further products in development or modified product currently or intent to continue the patent filing. This does not alter the adherence to PLOS ONE policies on sharing data and materials.

Objective: The aim of this survey is to determine the standard of practice of cricoid pressure application on rapid sequence induction in Ayder comprehensive specialized hospital from April 3 to May 3, 2019., Results: A total of 30 anesthetists were involved in the study with a response rate of 87%. Ninety percent of the respondents do not mask ventilate during rapid sequence induction and they do aspirate the naso-gastric tube if present. Almost half of the respondents have witnessed regurgitation during application of cricoid pressure and 93% do not remove the naso-gastric tube before rapid sequence induction. Seventy percent had experienced difficulty of endotracheal intubation during application of cricoid pressure. All of the respondents had less than 10 years of working experience as anesthetist.

Cricoid force is widely applied to decrease the risk of pulmonary aspiration and gastric antral insufflation of air during positive-pressure ventilation, yet its efficacy remains controversial. We compared manual oesophageal compression at the low left paratracheal and cricoid levels for the prevention of gastric antral air insufflation during positive-pressure ventilation by facemask in patients scheduled for elective surgery under general anaesthesia. After gaining written consent, participants were randomly allocated by sealed envelope to one of three groups: oesophageal compression by 30 N paratracheal force (paratracheal group); oesophageal compression by 30 N cricoid force (cricoid group); or no oesophageal compression (control group). Gastric insufflation of air was assessed before and after positive-pressure ventilation by ultrasound measurement of the antral cross-sectional area and/or presence of air artefacts in the antrum. The primary outcome measure was the proportion of participants with ultrasound evidence of gastric insufflation. We recruited 30 patients into each group. Before facemask ventilation, no air artefacts were visible in the antrum in any of the participants. After facemask ventilation of the participant's lungs, no air artefacts were seen in the paratracheal group, compared with six subjects in the cricoid group and eight subjects in the control group (p = 0.012). Our results suggest that oesophageal compression can be achieved by the application of manual force at the low left paratracheal level and that this is more effective than cricoid force in preventing air entry into the gastric antrum during positive-pressure ventilation by facemask., (© 2018 Association of Anaesthetists.)

Importance: The use of cricoid pressure (Sellick maneuver) during rapid sequence induction (RSI) of anesthesia remains controversial in the absence of a large randomized trial., Objective: To test the hypothesis that the incidence of pulmonary aspiration is not increased when cricoid pressure is not performed., Design, Setting, and Participants: Randomized, double-blind, noninferiority trial conducted in 10 academic centers. Patients undergoing anesthesia with RSI were enrolled from February 2014 until February 2017 and followed up for 28 days or until hospital discharge (last follow-up, February 8, 2017)., Interventions: Patients were assigned to a cricoid pressure (Sellick group) or a sham procedure group., Main Outcomes and Measures: Primary end point was the incidence of pulmonary aspiration (at the glottis level during laryngoscopy or by tracheal aspiration after intubation). It was hypothesized that the sham procedure would not be inferior to the cricoid pressure. The secondary end points were related to pulmonary aspiration, difficult tracheal intubation, and traumatic complications owing to the tracheal intubation or cricoid pressure., Results: Of 3472 patients randomized, mean (SD) age was 51 (19) years and 1777 (51%) were men. The primary end point, pulmonary aspiration, occurred in 10 patients (0.6%) in the Sellick group and in 9 patients (0.5%) in the sham group. The upper limit of the 1-sided 95% CI of relative risk was 2.00, exceeding 1.50, failing to demonstrate noninferiority (P = .14). The risk difference was -0.06% (2-sided 95% CI, -0.57 to 0.42) in the intent-to-treat population and -0.06% (2-sided 95% CI, -0.56 to 0.43) in the per protocol population. Secondary end points were not significantly different among the 2 groups (pneumonia, length of stay, and mortality), although the comparison of the Cormack and Lehane grade (Grades 3 and 4, 10% vs 5%; P <.001) and the longer intubation time (Intubation time >30 seconds, 47% vs 40%; P <.001) suggest an increased difficulty of tracheal intubation in the Sellick group., Conclusions and Relevance: This large randomized clinical trial performed in patients undergoing anesthesia with RSI failed to demonstrate the noninferiority of the sham procedure in preventing pulmonary aspiration. Further studies are required in pregnant women and outside the operating room., Trial Registration: ClinicalTrials.gov Identifier: NCT02080754.

Background: The use of cricoid pressure is controversial, and its ability to occlude the esophagus has been questioned. In this study, high-resolution solid-state manometry was used to analyze pressure changes in the upper esophagus from cricoid pressure during modified rapid sequence induction. This is a secondary analysis of data from a previous study., Methods: Seventeen healthy volunteers participated in a double-blind, randomized, placebo-controlled, cross-over study with primary aim to compare differences in the barrier pressure on the lower esophageal sphincter during rapid sequence induction with or without alfentanil. Standardized cricoid pressure of 30 N was applied 2 minutes after propolipid injection and held for 15 seconds and pressures in the esophagus were measured., Results: Cricoid pressure resulted in a pressure increase of 127 ± 98 mmHg (95% CI: 73-182) (placebo) and 123 ± 74 mmHg (95% CI: 84-162) (alfentanil) at the level of the upper esophageal sphincter (UES), compared to baseline. The pressure difference around the UES compared to the proximal esophagus during cricoid pressure application was 165 ± 100 mmHg (placebo) and 159 ± 87 mmHg (alfentanil) (mean ± 1 SD)., Conclusion: This study using high-resolution solid-state manometry under clinically relevant conditions shows that 30 N cricoid pressure generates high pressure in the area of the UES, far exceeding the levels previously considered necessary to prevent regurgitation. Additional studies are needed to clarify the effectiveness of cricoid pressure in preventing passive regurgitation before it is rejected as a part of rapid sequence induction., (© 2018 The Acta Anaesthesiologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.)

Objective: Vocal fold (VF) elongation vocal folds depends on two factors: the activity of the laryngeal muscles and the cricothyroid joint (CTJ). The aim of the study was to show the influence of the CTJ on VF elongation while singing a sustained vowel at different pitches., Study Design: Prospective study., Methods: Forty-nine female professional singers (25 sopranos, 24 altos) were recruited. Three-dimensional images of the larynx derived from high-resolution computed tomography scanning were obtained at the mean speaking fundamental frequency (F0) and one (F1) and two octaves (F2) above this pitch., Results: From F0 to F1, all three CTJ types showed equal elongation of the VF (type A: 14%, type B/C: 13%). From F1 to F2, VF elongation was 8% in singers with type A and 4% in those with type B/C (P < 0.0001)., Conclusion: The stability of the CTJ directly influences VF during singing. This is the first study to show this relationship in vivo., Level of Evidence: 4. Laryngoscope, 128:1176-1181, 2018., (© 2017 The American Laryngological, Rhinological and Otological Society, Inc.)

Objective: This study was a prospective, randomized controlled trial of rapid sequence intubation (RSI) with cricoid pressure (CP) within the emergency department (ED). The primary aim of the study was to examine the link between ideal CP and the incidence of aspiration., Method: Patients > 18 years of age undergoing RSI in the ED of two hospitals in New South Wales, Australia, were randomly assigned to receive measured CP using weighing scales to target the ideal CP range (3.060-4.075 kg) or control CP where the weighing scales were used, but the CP operator was blinded to the amount of CP applied during the RSI. A data logger recorded all CP delivered during each RSI. Immediately after intubation, tracheal and esophageal samples were taken and underwent pepsin analysis., Results: Fifty-four RSIs were analyzed (25 measured/29 control). Macroscopic contamination of the larynx at RSI was observed in 14 patients (26%). During induction (0-50 seconds), both groups delivered in-range CP. During intubation (51-223 seconds), laryngoscopy was associated with a reduction in mean CP below 3.060 kg in both groups. When compared, there was no statistically significant difference between the groups. For 11 patients, pepsin was detected in the oropharyngeal sample, while three were positive for tracheal pepsin. Seven patients (four control/three measured) were treated for clinical aspiration during hospitalization. As a result of the finding that neither group could maintain ideal range CP during laryngoscopy, the trial was abandoned., Conclusion: Laryngoscopy provides a counter force to CP, which is negated to facilitate tracheal intubation. The concept that a static 3.060 to 4.075 kg CP could be maintained during laryngoscopy and intubation was rejected by our study. Whether a lower CP range could prevent aspiration during RSI was not explored by this study., (© 2017 The Authors Academic Emergency Medicine published by Wiley Periodicals, Inc. on behalf of Society for Academic Emergency Medicine (SAEM).)

Background: We tested the hypothesis whether gender differences exist in the applied cricoid force necessary to prevent regurgitation. Real-time visual and dynamic means were used to assess the effectiveness of different applied cricoid forces in occluding the esophageal entrance in men (group 1) and in women (group 2)., Methods: In anesthetized and paralyzed patients, the glottis and esophageal entrance were visualized with a Glidescope video laryngoscope. Trained operators performed cricoid pressure (CP) and gastric tube insertion trials. Successful gastric tube insertion in the presence of CP was considered ineffective CP, whereas unsuccessful insertion was considered effective CP. The applied cricoid forces were measured with a novel instrument, the cricometer. The first patient in each group received 20 N. The applied cricoid force in successive patients was determined by the response of the previous patient within the same group, using the up-and-down sequential allocation technique., Results: In the 30 men and 30 women who qualified for the study, the median cricoid force (cricoid force = 50) that occluded the esophageal entrance was 30.8 N (95% confidence interval = 28.15-33.5) in men, and 18.7 N in women (95% confidence interval = 17.1-20.3; P < .0001). Patency of the esophageal entrance was observed when CP was not applied and when inadequate forces that allowed successful esophageal cannulation were used., Conclusions: The current study provides evidence that the median force necessary to occlude the esophageal entrance to prevent regurgitation is less in women compared with men. Applying the appropriate cricoid force in women should also decrease airway-related problems that tend to occur with the use of excessive forces. The findings of the current study may only be applicable to patients with normal body habitus.

Since cricoid pressure was introduced into clinical practice, controversial issues have arisen, including necessity, effectiveness in preventing aspiration, quantifying the cricoid force, and its reliability in certain clinical entities and in the presence of gastric tubes. Cricoid pressure-associated complications have also been alleged, such as airway obstruction leading to interference with manual ventilation, laryngeal visualization, tracheal intubation, placement of supraglottic devices, and relaxation of the lower esophageal sphincter. This review synthesizes available information to identify, address, and attempt to resolve the controversies related to cricoid pressure. The effective use of cricoid pressure requires that the applied force is sufficient to occlude the esophageal entrance while avoiding airway-related complications. Most of these complications are caused by excessive or inadequate force or by misapplication of cricoid pressure. Because a simple-to-use and reliable cricoid pressure device is not commercially available, regular training of personnel, using technology-enhanced cricoid pressure simulation, is required. The current status of cricoid pressure and objectives for future cricoid pressure-related research are also discussed.

Objectives: This study aims to investigate the relationship between the anterior cricothyroid (CT) space at rest with vocal range in female singers. Potential associations with and between voice categories, age, ethnicity, anthropometric indices, neck dimensions, laryngeal dimensions, vocal data along with habitual speaking fundamental frequency were also explored., Study Design: This is a cohort study., Methods: Laryngeal dimensions anterior CT space and heights of the thyroid and cricoid cartilages were measured using ultrasound in 43 healthy, classically trained, female singers during quiet respiration. Voice categories (soprano and mezzo-soprano), age, ethnicity, weight, height, body mass index, neck circumference and length, anterior thyroid and cricoid cartilage heights, practice and performance vocal range, lowest and highest practice and performance notes along with habitual speaking fundamental frequency were collected., Results: The main finding was that mezzo-sopranos have a significantly wider resting CT space than sopranos (11.6 mm versus 10.4 mm; P = 0.007). Mezzo-sopranos also had significantly lower "lowest and highest" performance notes than sopranos. There was no significant correlation between the magnitudes of the anterior CT space with vocal range. The participants with the narrowest and widest anterior CT space had similar vocal ranges., Conclusions: These results suggest that the CT space is not the major determinant of performance vocal range., (Copyright © 2017 The Voice Foundation. Published by Elsevier Inc. All rights reserved.)

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., (Copyright © 2016 The Voice Foundation. Published by Elsevier Inc. All rights reserved.)

To assess the degree to which cricoid pressure (Sellick manoeuvre) actually compresses the oesophagus, we measured the effect of cricoid pressure and paralaryngeal pressure on the outer anteroposterior diameter of the upper oesophagus with ultrasound in 39 healthy volunteers. The mean (SD) outer anteroposterior oesophageal diameter was 0.77 (0.11) cm with no pressure, 0.79 (0.13) cm with the application of cricoid pressure of 30 N and 0.68 (0.12) cm with the application of paralaryngeal pressure of 30 N (p < 0.0001). If cricoid pressure does not reduce the anteroposterior diameter of the oesophagus, it is difficult or impossible to explain the efficacy of the Sellick manoeuvre. However, paralaryngeal pressure decreases this diameter and has the potential to occlude the upper oesophagus., (© 2016 The Association of Anaesthetists of Great Britain and Ireland.)

Background: It has been proposed that cricoid pressure can exacerbate an unstable cervical injury and lead to neurologic deterioration., Objective: We sought to examine the amount of motion cricoid pressure could cause at an unstable subaxial cervical spine injury, and whether posterior manual support is of any benefit., Methods: Five fresh, whole cadavers had complete segmental instability at C5-C6 surgically created by a fellowship-trained spine surgeon. Cricoid pressure was applied to the anterior cricoid by an attending anesthesiologist. In addition, the effect of posterior cervical support was tested during the trials. The amount of angular and linear motion between C5 and C6 was measured using a Fastrak, three-dimensional, electromagnetic motion analysis device (Polhemus Inc., Colchester, VT)., Results: When cricoid pressure is applied, the largest angular motion was 3 degrees and occurred in flexion-extension at C5-C6. The largest linear displacement was 1.36 mm and was in anterior-posterior displacement of C5-C6. When manual posterior cervical support was applied, the flexion-extension was improved to less than half this value (1.43 degrees), and this reached statistical significance (p = 0.001). No other differences were observed to be significant in the other planes of motion with the applications of support., Conclusions: Based on the evidence presented, we believe that the application of cricoid pressure to a patient with a globally unstable subaxial cervical spine injury causes small displacements. There may be some benefit to the use of manual posterior cervical spine support for reducing motion at such an injured segment., (Copyright © 2016 Elsevier Inc. All rights reserved.)

Background: It is unclear how cricoid pressure affects tracheal intubation with the Pentax-AWS Airwayscope(®) (AWS). We conducted a prospective randomized clinical trial in anaesthetized patients., Methods: Sixty patients were allocated to either the cricoid pressure (CP) group (n=30) or the sham group (n=30). We compared the two groups with regard to intubation time, number of attempts required for insertion of the Intlock blade (disposable blade of the AWS) and tracheal intubation, percentage of glottic opening (POGO) score, and subjective difficulty of both laryngoscopy and passage of a tube through the glottis., Results: Intubation time was significantly longer in the CP group (median 45[IQR40-59] s) than in the sham group (32[28-45] s) (P=0.003, 95% CI for median difference 5-24 s). The number required for insertion of the Intlock blade did not differ between the groups (P=0.08), but the number for tracheal intubation was significantly higher in the CP group (1 attempt in 14 patients, 2 in 7, 3 in 9) than in the sham group (1 attempt in 24 patients, 2 in 6; P=0.002). POGO score did not differ significantly between the groups (P=0.60), nor did the subjective difficulty of laryngoscopy (P=0.06). The visual analogue scale score for passage of a tube through the glottis was significantly higher in the CP group than in the sham group (P<0.001)., Conclusions: Cricoid pressure impedes tracheal intubation using the AWS, and is associated with longer intubation time, which can be attributed to increased difficulty in the passage of a tube through the glottis., Clinical Trial Registry Number: UMIN000018209., (© The Author 2016. Published by Oxford University Press on behalf of the British Journal of Anaesthesia. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

Although it is known vocal fold adduction is achieved through laryngeal muscle activation, it is still unclear how interaction between individual laryngeal muscle activations affects vocal fold adduction and vocal fold stiffness, both of which are important factors determining vocal fold vibration and the resulting voice quality. In this study, a three-dimensional (3D) finite element model was developed to investigate vocal fold adduction and changes in vocal fold eigenfrequencies due to the interaction between the lateral cricoarytenoid (LCA) and thyroarytenoid (TA) muscles. The results showed that LCA contraction led to a medial and downward rocking motion of the arytenoid cartilage in the coronal plane about the long axis of the cricoid cartilage facet, which adducted the posterior portion of the glottis but had little influence on vocal fold eigenfrequencies. In contrast, TA activation caused a medial rotation of the vocal folds toward the glottal midline, resulting in adduction of the anterior portion of the glottis and significant increase in vocal fold eigenfrequencies. This vocal fold-stiffening effect of TA activation also reduced the posterior adductory effect of LCA activation. The implications of the results for phonation control are discussed.

We studied 40 adult patients to see if cricoid pressure affected placement of the I-gel(™). In a randomised crossover design, the i-gel was placed with and without cricoid pressure, and we compared the success rate of adequate ventilation through the i-gel, time to placement and the rate of optimal position of the device between the two circumstances. Cricoid pressure significantly decreased the success rate of adequate ventilation through the i-gel (40 vs 34 patients) (p = 0.041, 95% CI for difference 4-26%), and significantly decreased the rate of the optimal position (39 vs 17 patients) (p < 0.001). The time to achieve adequate ventilation was significantly longer (p < 0.001) with cricoid pressure than without (median difference 8 s; 95% CI for median difference 3-12 s). Cricoid pressure significantly decreases the success rate of ventilation through the i-gel, but the success rate of ventilation through the i-gel is reasonably high., (© 2014 The Association of Anaesthetists of Great Britain and Ireland.)

Background: In the last 2 decades, the effectiveness of cricoid pressure (CP) in occluding the esophageal entrance has been questioned. Recent magnetic resonance imaging studies yielded conflicting conclusions. We used real-time visual and mechanical means to assess the patency of the esophageal entrance with and without CP in anesthetized and paralyzed adult patients., Methods: One hundred seven, nonobese ASA physical status I and II patients were recruited for the study. A cricoid force of 30 N was used. This force was standardized by using a weighing scale before application of CP in each patient. After oxygen administration, anesthetic induction, neuromuscular blockade, and establishment of manual ventilation with FIO2 = 1.0, the view of the glottis and esophageal entrance was visualized, and video recordings were obtained by using a Glidescope video laryngoscope. Attempts to insert 2 gastric tubes (GTs), size 12 and 20 F, into the esophagus were made by a "blinded" operator without and with CP, the timing of which was randomized. A successful insertion of a GT in the presence of CP was considered evidence of a patent esophageal entrance (ineffective CP), whereas an unsuccessful insertion of a GT was considered evidence of an occluded esophageal entrance (effective CP). After the attempts to insert the GTs were completed, tracheal intubation was performed while CP was applied. The position of the esophageal entrance in relation to the glottis (midline versus lateral) was assessed from the video recordings, with and without CP., Results: We stopped the study when 79 patients (41 men and 38 women) qualified for and completed the study (2-sided Clopper-Pearson confidence interval (CI) 95% to 100%, n = 72). Advancement of either size GT into the esophagus could not be accomplished during CP in any patient but was easily done in all subjects when CP was not applied. This occurred whether the esophageal entrance was in a midline position or in a left or right lateral position relative to the glottis. Esophageal patency was visually observed in the absence of CP, whereas occlusion of the esophageal entrance was observed during CP in all patients. Without CP, the esophageal entrance was in a left lateral position in relation to the glottis in 57% ([95 % CI, 45%-68%)] of patients, at midline in 32% (CI, 22%-43%), and in a right lateral position in 11% (CI, 5%-21%). The position did not change with CP., Conclusions: The current study provides additional visual and mechanical evidence supporting a success rate of at least 95% by using a cricoid force of 30 N to occlude the esophageal entrance in anesthetized and paralyzed normal adult patients. The efficacy of the maneuver was independent of the position of the esophageal entrance relative to the glottis, whether midline or lateral.

Objectives: The purpose of this study was to develop a methodology and standard settings for ultrasound study of the upper esophageal sphincter (UES) during swallowing., Material and Methods: This was a prospective study of 25 healthy volunteers (15 women and 10 men) aged 20 to 56 years. Neck ultrasonography was performed as each volunteer swallowed 10 mL of water three times. The parameters studied were: diameter of the closed UES; diameter of the open UES; anterior and lateral displacement (measured in cm) of the UES as the water bolus flowed through it; duration of UES opening; and average duration of UES displacement (measured in ms). Student's t tests for paired and unpaired samples were applied for the statistical analysis., Results: The mean diameter of the closed UES was 0.78 ± 0.13 cm, while the mean duration of opening was 415 ± 57.66 ms and the mean duration of displacement was 937 ± 120.98 ms. Maximum anterior and lateral displacement of the UES was 0.42 ± 0.12 cm and 0.35 ± 0.18 cm, respectively. There was a significant difference between men and women for lateral displacement of the UES (P=0.04)., Conclusion: This study established standards for ultrasound study of the UES during swallowing, using a non-invasive readily accessible method that may be useful for assessing swallowing disorders involving the UES (Zenker's diverticulum, fibrosis, stricture)., (Copyright © 2013 Elsevier Masson SAS. All rights reserved.)

Study Objective: Cricoid pressure may negatively affect laryngeal view and compromise airway patency, according to previous studies of direct laryngoscopy, endoscopy, and radiologic imaging. In this study, we assess the effect of cricoid pressure on laryngeal view with a video laryngoscope, the Pentax-AWS., Methods: This cross-sectional survey involved 50 American Society of Anesthesiologists status I and II patients who were scheduled to undergo elective surgery. The force measurement sensor for cricoid pressure and the video recording system using a Pentax-AWS video laryngoscope were newly developed by the authors. After force and video were recorded simultaneously, 11 still images were selected per 5-N (Newton; 1 N = 1 kg·m·s(-2)) increments, from 0 N to 50 N for each patient. The effect of cricoid pressure was assessed by relative percentage compared with the number of pixels on an image at 0 N., Results: Compared with zero cricoid pressure, the median percentage of glottic view visible was 89.5% (interquartile range [IQR] 64.2% to 117.1%) at 10 N, 83.2% (IQR 44.2% to 113.7%) at 20 N, 76.4% (IQR 34.1% to 109.1%) at 30 N, 51.0% (IQR 21.8% to 104.2%) at 40 N, and 47.6% (IQR 15.2% to 107.4%) at 50 N. The number of subjects who showed unworsened views was 20 (40%) at 10 N, 17 (34%) at 20 and 30 N, and 13 (26%) at 40 and 50 N., Conclusion: Cricoid pressure application with increasing force resulted in a worse glottic view, as examined with the Pentax-AWS Video laryngoscope. There is much individual difference in the degree of change, even with the same force. Clinicians should be aware that cricoid pressure affects laryngeal view with the Pentax-AWS and likely other video laryngoscopes., (Copyright © 2012. Published by Mosby, Inc.)

Background: In some categories of patients, a rapid sequence induction using a fibre-optic method may be indicated. The aim of the present study was to examine the effect of cricoid pressure (CP) on the duration of fibre-optic intubation. The hypothesis was that CP would prolong the intubation time., Methods: The study was a randomised, double-blind, cross-over study. The patients were intubated twice, in a randomised way, using a flexible fibrescope once with and once without CP. The intubation time and the visualisation of the glottis were registered. If the intubation was not completed within 180 s, it was registered as failed. CP was standardised to a pressure of 30 N. The data are given as the mean (standard deviation) or median [interquartile] (range)., Results: Fifty patients were included, with a mean age of 53 years (14.6) and mean body mass index of 26.4 (4.3). Three intubations without and 13 intubations with CP failed. The durations of intubation without and with CP were 59 s [53-79 s] (34-144 s) and 75 s [67-104 s] (43-179 s), respectively (P < 0.001)., Conclusion: The study showed that CP prolongs the duration of fibre-optic intubation in patients with Mallampati grades 1-2., (© 2012 The Acta Anaesthesiologica Scandinavica Foundation.)

A short-cut review was carried out to establish whether the application of cricoid pressure during the induction of general anaesthesia reduced the incidence of regurgitation and aspiration of gastric contents. One good quality review article, two studies and two abstracts provided the best evidence to answer the clinical question. The authors, date and country of publication, patient group studied, study type, relevant outcomes, results and study weaknesses of these best papers are tabulated (table 1). It is concluded that although there is a theoretical advantage to providing cricoid pressure during induction, there is little evidence of any benefit at this time.

Cricoid pressure has been long used by clinicians to reduce the risk of aspiration during tracheal intubation. Historically, it is defined by Sellick as temporary occlusion of the upper end of the oesophagus by backward pressure of the cricoid cartilage against the bodies of the cervical vertebrae. The clinical relevance of cricoid pressure has been questioned despite its regular use in clinical practice. In this review, we address some of the controversies related to the use of cricoid pressure.

Objectives/hypothesis: Our aim was to use three-dimensional computed tomography (3DCT) to examine arytenoid cartilage movement during a high-pitched tone task., Study Design: This was a prospective study., Methods: This study included 14 patients with male-to-female gender identity disorder who had undergone 3DCT imaging for surgical simulation between January 2007 and May 2008. First, to prove that the phonation condition was indeed one of the high-pitched phonation, we confirmed the rotational movement of the thyroid cartilage, horizontal gliding movement of the inferior horn, and vocal fold elongation on a high-pitched tone task. Next, we detected the arytenoid cartilage positions of the joint during a comparison of comfortable and high-pitched phonations. We measured the movement direction and movement distance of the arytenoid cartilage., Results: In all cases, the cricothyroid space became narrower (rotation movement), and we observed anterior gliding movement of the inferior horn. In all cases, elongation of the vocal folds by the high-pitched phonation was confirmed and the arytenoid cartilages were displaced both anteriorly and caudally from the position during comfortable phonation by the high-pitched tone task., Conclusions: The arytenoid cartilages did not move posteriorly to elongate the vocal folds during high-pitched phonation. The arytenoid cartilages were pulled anteriorly and moved caudally because of tension associated with vocal fold elongation because of the task of high-pitched phonation. These results suggest that there are no movements at the cricoarytenoid joint that directly control the length of the vocal folds in accordance with pitch., (Copyright © 2012 The Voice Foundation. Published by Mosby, Inc. All rights reserved.)

Background: Cricoid pressure is a routine component of rapid sequence induction and is designed to reduce the risk of reflux and its associated morbidity. Recent studies have raised questions regarding the efficacy of cricoid pressure in terms of changes in the pharyngeal and esophageal anatomy., Objective: This current descriptive study was designed to observe the anatomical effect of cricoid pressure on the occlusion of esophageal lumen in conscious volunteers using magnetic resonance imaging (MRI)., Methods: We quantitatively assessed esophageal patency before and during application of cricoid pressure in 20 awake volunteers utilizing MRI., Results: Target cricoid pressure was achieved in 16 of 20 individuals, corresponding to a mean percentage reduction in cricovertebral distance of 43% (range 25-80%). Cricoid pressure was applied incorrectly in 4 (20%) individuals as evidenced by no change in the cricovertebral distance. Incomplete esophageal occlusion was seen in 10 of 16, or 62.5% (95% confidence interval 35-85%) of individuals when appropriate cricoid pressure was applied. Incomplete esophageal occlusion was always associated with a lateral deviation of the esophagus. None of the 6 subjects with complete occlusion had esophageal deviation during the appropriate application of cricoid pressure., Conclusion: Effective application of cricoid pressure by an experienced operator frequently resulted in lateral deviation of the esophagus and incomplete occlusion of esophageal lumen. Reliance on cricoid pressure for esophageal occlusion requires further evaluation utilizing functional studies., (Copyright © 2012 Elsevier Inc. All rights reserved.)

This article reports the results of a multiparametrical analysis of Mongolian Long Song, characterised by multiple ornamentation and shows the similarities between the laryngeal behaviour observed during these ornamentations and the compensatory gesture produced by patients after supracricoid partial laryngectomy. This study includes (1) a physiological analysis of videofiberscopic laryngeal data from a healthy Mongolian singer and from three non-singer French-speaking clinical patients; and (2) an acoustical analysis (fundamental frequency and intensity). For the singer, the fiberoptic analysis showed two main laryngeal behaviours in producing ornamentations: (1) 'lyrical' vibratos mobilising the entire laryngeal block; (2) 'Mongolian' trills with essentially supraglottic movements, the arytenoids being mobilised independently of the rest of the laryngeal block. Patients demonstrated similar aryepiglottic trilling to fulfil a function of voicing. The acoustic analysis showed that the fundamental frequency and the intensity were in phase for vibrato, contrary to the 'Mongolian' trills which were in opposite phase, underlying a change of laryngeal vibratory mechanisms.

The region posterior to the cricoid cartilage is challenging to assess fluoroscopically. The purpose of this investigation is to critically evaluate the posterior cricoid (PC) region on fluoroscopy and describe patterns of common findings. This was a case control study. All fluoroscopic swallowing studies performed between June 16, 2009, and February 9, 2010, were reviewed for features seen in the PC region. These findings were categorized into distinct patterns and compared to fluoroscopic studies performed in a cohort of normal volunteers. Two hundred patient studies and 149 healthy volunteer studies were reviewed. The mean age of the referred patient cohort and the volunteer cohort was 57 years (±19) and 61 years (±16), respectively (p > 0.05). The patient cohort was 53% male and the control cohort was 56% female (p > 0.05). Four groups were identified. Pharyngoesophageal webs were seen in 7% (10/149) of controls and 14% (28/200) of patients (p = 0.03). A PC arch impression was seen in 16% of patients (32/200) and controls (24/149) (p = 1). A PC plication was demonstrated in 23% (34/149) of controls and 30% (60/200) of patients (p = 0.13). No distinctive PC region findings were seen in 54% (81/149) of controls and 42% (84/200) of referred patients (p = 0.02). Four patients (2%) had both a web and a PC plication. Four categories of PC region findings were identified (unremarkable PC region, web, PC arch impression, and PC plication). Both patients referred for swallowing studies and healthy volunteers demonstrated esophageal webs, PC arch impressions, and PC plications. Only webs were more common in patients than in control subjects (p = 0.03). The PC impression and PC plication are likely to represent normal variants that may be identified on fluoroscopic swallow studies.

Objectives/hypothesis: Cricothyroid approximation (CTA) surgery aims at raising the voice pitch in male-to-female transsexuals. However, 30% of the patients are not satisfied with the result. The purpose of our study was to examine the cricothyroid joint (CTJ) biomechanics and to analyze if (and how) the CTJ anatomy influences the movement of the cricoid and, consequently, the elongation of the vocal fold and the voice pitch after CTA., Methods: Twenty-four cadaver larynges were examined with high-resolution computerized tomography and MIMICS three-dimensional imaging software (Materialise Interactive Medical Image Control System, Leuven, Belgium). After superimposing the two scans taken in "neutral" and in "CTA" positions, vector geometrical analysis was used to determine the effective rotation axis of the CTJ and to calculate the elongation of the vocal folds after CTA., Results: Our results showed that the cricoid rotates around an axis, the position of which depends on the anatomical structure of the CTJ. Based on the location of this effective rotation axis, we could distinguish three groups. In group I (N=13), the rotation axis was located in the lower third; in group II (N=5), it was located in the middle third; and in group III (N=6), it was located in the upper third of the cricoid. The elongations of the vocal fold were 12%, 8%, and 3%, in groups I, II, and III, respectively., Conclusions: The anatomical structure of the CTJ influences directly (1) the position of the effective rotation axis and (2) the elongation of the vocal folds., (Copyright © 2011 The Voice Foundation. Published by Mosby, Inc. All rights reserved.)

Objectives/hypothesis: Laryngeal framework surgery requires a good understanding of the biomechanics of the cricoarytenoid (CA) joint, the precise function of which is still only poorly understood. The aim of the study was (1) to show that, by superimposing two or more three-dimensional (3D) images, we can visualize the exact position of the arytenoid cartilages within the larynx at different phases of their movement; and (2) to demonstrate that it is possible to analyze the arytenoid cartilage movements mathematically with the help of vector analysis., Study Design: In vitro cadaver study., Methods: Twenty fresh and intact cadaver larynges were scanned by high-resolution computerized tomography with the arytenoid cartilages in "respiratory" position and in "phonatory" position. The two positions were superimposed and rendered in 3D with MIMICS (Materialise Interactive Medical Image Control System, Leuven, Belgium). The spatial trajectory of the arytenoid cartilage movements was calculated with vector analysis., Results: The movement from the "respiratory" to the "phonatory" position has three components: (1) an inward rocking action around the longitudinal CA joint; (2) a forward sliding movement along the longitudinal axis of the CA joint; and (3) an inward rotation around a virtual axis that runs perpendicular to the CA joint axis., Conclusions: Superimposing 3D images of the larynx with the help of the software package MIMICS allows us to visualize and to analyze mathematically the trajectory of the arytenoid cartilage. The arytenoid cartilages rock inward, slide forward, and rotate inward when they move from the "respiratory" to the "phonatory" position., (Copyright © 2011 The Voice Foundation. Published by Mosby, Inc. All rights reserved.)

Aspiration pneumonitis (Mendelson's syndrome) is universally accepted as a complication of general anaesthesia. According to Ellis et al (2007) death from aspiration was first described by Simpson in 1848, and it was not until 1946 that Mendelson identified acid aspiration in a significant number of obstetric patients undergoing facemask anaesthesia. The advent of techniques to secure the airway, through the use of airway adjuncts has gone some way to reduce the likely incidence of aspiration in today's perioperative arena. The positive outcome for patients is corroborated by Neilipovitz & Crosby (2007) who report aspiration as a rare complication with an overall incidence of 1:2,000-3,000. As Ewart (2007) highlights, Mendelson's syndrome is due to pharmacological effects at a molecular level which occur in the airway tissues and are caused by the use of induction and neuromuscular blocking agents. The resultant loss of consciousness and consequent diminished protective airway reflexes ultimately places the patient at risk until their airway is secured. Preventative measures to protect the lung from contamination with gastric contents, for example preoperative fasting, are therefore instigated prior to securing the airway.

This report describes cartilaginous regeneration in a cricoarytenoid joint affected by spondyloarthropathy using tumor necrosis factor-alpha (TNF-α) blockade, monitored by magnetic resonance (MR) and computed tomography (CT) imaging. This case is interesting for several reasons. It is only the eighth case of destructive ankylosing spondylitis-related cricoarytenoid arthritis published in the English language literature. It describes, for the first time, full recovery of vocal cord mobility following TNF-α blockade. It is also the first case to be published with MR imaging demonstrating regeneration of the cricoarytenoid cartilage following treatment. This case represents a landmark in the treatment of patients presenting with destructive arthritis involving the cricoarytenoid joint., (Copyright © 2011 The American Laryngological, Rhinological, and Otological Society, Inc.)

Background: Cricoid pressure has been shown to decrease the pressure in the lower esophageal sphincter (LES), increasing the risk of aspiration. Whether this reaction is due to pain associated with the application of cricoid pressure has not been studied. The aim of this study was to compare the effects of cricoid pressure with those of peripheral pain on pressures in the LES, and to study whether remifentanil influences these effects. Data from the upper esophageal sphincter (UES) are also described., Methods: Continuous solid-state manometry was performed in 14 healthy volunteers. Initially, the effect of remifentanil (target-controlled infusion with a plasma target concentration of 5.0 ng/ml) was studied, and thereafter, the effects of cricoid pressure and peripheral pain stimulation (cold stimulation). Finally, these two interventions were repeated under ongoing remifentanil infusion., Results: Remifentanil decreased the LES pressure significantly [ΔP-6.5 mmHg, 95% confidence interval (95% CI) -1.7 to -11.2]. Cricoid pressure application decreased the LES pressure significantly (ΔP-3.7 mmHg, 95% CI -1.4 to 6.1), whereas peripheral pain did not (ΔP 1.2 mmHg, 95% CI -3.5 to 1.1). Under ongoing remifentanil infusion, no cricoid pressure-induced LES relaxation was observed. Cricoid pressure induced high pressures in the area of the UES, 215.7 (±91.2) mmHg without remifentanil vs. 219.4 (±74.2) mmHg with remifentanil., Conclusions: Remifentanil as well as cricoid pressure per se induced decreases in LES pressure. However, cricoid pressure-induced changes of the barrier pressure were not significant whether induced with or without an infusion of remifentanil., (© 2011 The Authors. Journal compilation © 2011 The Acta Anaesthesiologica Scandinavica Foundation.)

Background: In 1961, Sellick described a three-finger technique of cricoid pressure used to prevent gastric regurgitation during induction of anesthesia. The "Sellick maneuver" is now used worldwide. The authors have observed great variability in the application of cricoid pressure by health care providers and have suspected that misapplication occurs. The objectives of this observational study were to determine how many different techniques of cricoid pressure were being used and to identify the reasons for such variability of technique., Methods: During a 30-month period, the authors observed 32 health care providers applying cricoid pressure at five hospitals. The technique and the professional degree of the person performing the maneuver were recorded. We also reviewed five national courses that provide airway management training to determine which technique of cricoid pressure was being taught., Results: Ten different techniques of cricoid pressure were identified in 32 observations. We identified cases in which pressure was mistakenly applied to the thyroid cartilage and sternocleidomastoid muscles. The original three-finger Sellick technique was rarely used (3 of 32). A review of five national training courses revealed that none provide specific cricoid pressure training., Conclusion: This observational study demonstrates that there is great variability in the application of cricoid pressure, identifying 10 different techniques in 32 observations. Misapplication does occur with possible patient harm. We suggest four possible reasons for this variability of technique. The authors use the three-finger cricoid pressure technique as originally described by Sellick and thought that this technique is effective, easy to teach, and safely keeps the fingers in the midline of the cricoid cartilage.

Emergency patients need special considerations and the number and severity of complications from general anaesthesia can be higher than during scheduled procedures. Guidelines are therefore needed. The Clinical Practice Committee of the Scandinavian Society of Anaesthesiology and Intensive Care Medicine appointed a working group to develop guidelines based on literature searches to assess evidence, and a consensus meeting was held. Consensus opinion was used in the many topics where high-grade evidence was unavailable. The recommendations include the following: anaesthesia for emergency patients should be given by, or under very close supervision by, experienced anaesthesiologists. Problems with the airway and the circulation must be anticipated. The risk of aspiration must be judged for each patient. Pre-operative gastric emptying is rarely indicated. For pre-oxygenation, either tidal volume breathing for 3 min or eight deep breaths over 60 s and oxygen flow 10 l/min should be used. Pre-oxygenation in the obese patients should be performed in the head-up position. The use of cricoid pressure is not considered mandatory, but can be used on individual judgement. The hypnotic drug has a minor influence on intubation conditions, and should be chosen on other grounds. Ketamine should be considered in haemodynamically compromised patients. Opioids may be used to reduce the stress response following intubation. For optimal intubation conditions, succinylcholine 1-1.5 mg/kg is preferred. Outside the operation room, rapid sequence intubation is also considered the safest method. For all patients, precautions to avoid aspiration and other complications must also be considered at the end of anaesthesia.

Background: The backward, upward and rightward pressure (BURP) maneuver and cricoid pressure (CP) are easily confused because of their similarities. We surveyed nurses to determine their knowledge and skills regarding these maneuvers., Methods: Forty nurses (OR, n=20; ER, n=20) answered questionnaires regarding BURP and CP, and were then asked to apply CP to a laryngopharynx model equipped with a digital scale to measure compression force., Results: As for the BURP maneuver, 26 nurses (OR 20, ER 6) noted previous experience, while only 13 (OR 3, ER 10) and 1 (OR) nurses answered correctly regarding the compression point and correct direction, respectively. As for CP, 16 nurses (OR 14, ER 2) noted previous experience, but only 3 (all ER) answered correctly. Twenty-six nurses (OR 16, ER 10) incorrectly compressed the thyroid cartilage on the laryngopharynx model, and 24 (OR 18, ER 6) incorrectly applied backward and upward pressure, which was significantly frequent among the OR nurses. The measured forces of CP were 2.11 +/- 1.3 kg (mean +/- SD) and 2.5 +/- 2.1 kg for the OR and ER nurses, respectively, which were not significantly different., Conclusions: We found that the nurses are confused with the BURP and CP maneuvers. Unless applied correctly, these maneuvers may interfere with tracheal intubation. Constant education and training are essential for effective and safe implementation of these maneuvers.

Objectives: This is the first study to look at the effects of cricoid pressure/laryngeal manipulation on the laryngeal view and intubation success in the emergency or pre-hospital environment. Cricoid pressure is applied in the hope of reducing the incidence of aspiration. However the technique has never been evaluated in a randomized trial and may adversely affect laryngeal view. In order to improve intubating conditions cricoid pressure may be released and the larynx manipulated into a more favourable position., Methods: We carried out a prospective observational study to evaluate the effects of cricoid pressure and laryngeal manipulation on laryngeal view in our physician led pre-hospital trauma service., Results: 402 patients were included over a 16-month period. We intubated 98.8% patients on the first or second attempt. In 61 intubations (in 55 patients, 13.6%) the larynx required manipulation to facilitate intubation. In 22 intubations cricoid pressure was removed with the laryngeal view improving in 50%. Bimanual laryngeal manipulation was used in 25 intubations and the larynx better visualised in 60% of these. Backwards upwards rightwards pressure was applied to the larynx in 14 intubations and the laryngeal view improved in 64%. Two patients regurgitated when cricoid pressure was released. Both had prolonged periods of bag valve mask ventilation and difficult intubations., Discussion: The results suggest that cricoid pressure should be removed if the laryngeal view obtained is not sufficient to allow immediate intubation. Further manipulation of the larynx is likely to improve the chances of successful tracheal tube placement.

Background: Our aim was to investigate the clinical and manofluorographic findings of patients with anterior cervical osteophyte (ACO) dysphagia before and after surgery., Methods: Chart review including manofluorography (MFG) data of patients undergoing ACO removal was undertaken., Results: Thirteen patients underwent transcervical ACO removal over a 10-year period. A postoperative hematoma was the only surgical complication. Overall, there was a significant postoperative decrease in Functional Outcome Swallowing Scale (FOSS). MFG data showed an elevated preoperative intrabolus pressure gradient across the osteophyte (IB-Gra), 39.78 mm Hg, and IB-Gra significantly decreased to 19 mm Hg 6 months after surgery., Conclusion: Functional (FOSS) and objective MFG (IB-Gra) improvements occurred in patients who had ACO dysphagia and underwent surgery. These findings support high IB-Gra as a reliable objective indicator for surgical intervention for ACO dysphagia and IB-Gra as an appropriate parameter for follow-up after ACO removal. In selected patients, ACO removal by anterolateral-transcervical approach is a safe and highly effective treatment.

Cricothyroidotomy is the final rescue maneuver in difficult airway management. We compared 4 techniques of oxygenation via the cricothyroid membrane in a manikin. The techniques were wire guided, trocar, cannula with jet ventilation, and blade technique (scalpel with endotracheal tube). In the wire-guided group, the time taken to ventilation was slower on all attempts, and there were no successful attempts in <40 seconds. There were no differences between the other groups at any time. Time to ventilation improved with repetition in all groups. Skills were retained at 1 month.

Postoperative long-term treatment problems of male-to-female transsexuals can be caused by the underestimated mobility of the cricothyroid joint. One hundred cadaveric larynges were analysed to reveal the morphological and functional anatomy of the CTJ focusing on possible horizontal and vertical gliding movements. Furthermore, the distance of the cricothyroid space for rotational movements was measured. The articular surface of the cricothyroid joint showed three different possibilities: a well-defined facet (Type 1 61%), no definable facet (Type 2 22%) or a flat surface with or without a tiny protuberance (Type 3 17%). Side different statements and intraindividual differences between male and female specimens were included. These different types affect horizontal and vertical gliding movements, besides rotational movements. The mobility between Type 1 and the others was highly significant (P < 0.001). Regarding different motions in the cricothyroid joint, rotational movements caused significant elongation of the vocal folds, which should be taken into consideration for phonosurgical methods.

Head rotation is widely used as one of the postural techniques for dysphagic patients. However, it cannot be used for patients with severe limitations to the range of motion of the neck. The purpose of this study was to determine the effect of applying pressure to the cricoid while swallowing and to explore the possibility of this maneuver as an alternative to head rotation. The swallowing function of 12 volunteers was examined with videofluorography under nine conditions: neutral, head rotated to the right, head rotated to the left, applying pressure to the cricoid on the right side at 5, 10, and 15 N, and applying pressure to the cricoid on the left side at 5, 10, and 15 N. To examine the effect of this maneuver on pharyngeal swallowing, the laterality of bolus flow was evaluated using 3 ml barium thin liquid from the posterior-anterior (P-A) view. The "pressing-cricoid" maneuver significantly altered the laterality of the bolus flow; the bolus flow was shifted to the side opposite to which the pressure was applied. The results of these changes were similar to those achieved with head rotation. These results demonstrated that the "pressing-cricoid" maneuver changes the bolus flow. This maneuver may have therapeutic value for the treatment of dysphagic patients as an alternative to head rotation.

Objective: To investigate the time interval between glottic closure and the opening of upper esophageal sphincter during swallowing, by means of the coupling of electromyographical (EMG) recordings on the thyroarytenoid (TA) and the cricopharyngeus (CP) muscles., Methods: TA-EMG and CP-EMG pause were recorded by concentric needle electrodes using time-locked delay-line circuitry of the EMG apparatus. EMG data obtained from a total of 273 swallows of saliva, 3, 5, 10 and 15 ml volumes of water, were compared., Results: The relation between the onsets of TA-EMG activity and the CP-EMG pause demonstrated three different patterns of swallows. Pattern A was the delay of the onset of TA-EMG between 50-500 ms, and pattern B was the overlap of its activity with the CP-EMG pause. Pattern C was the earlier occurrence of the TA-EMG 50-550 ms before the CP-EMG pause. Pattern A was the most frequent type of swallows whereas the pattern C appeared during swallowing of larger volumes., Conclusions: Physiologically, there is a delay of the TA activation after the onset of CP-EMG pause during swallowing of small amounts in healthy subjects., Significance: This physiological phenomenon could be a potential risk of aspiration in patients with neurogenic dysphagia.