Relationship between severe obesity and depth to the cricothyroid membrane in third-trimester non-labouring parturients: a prospective observational study.

BACKGROUND: Severely obese parturients have increased 'cannot intubate, cannot oxygenate' risk during Caesarean section under general anaesthesia. Front-of-neck access (FONA) at the cricothyroid membrane (CTM) is definitive management; however, attempted FONA can fail. Point-of-care ultrasonography may provide useful information about CTM depth to aid FONA in obesity. This study determined the difference in CTM depth between severely obese and non-obese parturients, utilising ultrasonography. METHODS: In this prospective observational study, two anaesthetists performed airway ultrasonography on 15 severely obese (BMI >45 kg m-2) and 15 normal-weight (BMI ≤25 kg m-2) parturients in the third trimester, using the transverse and longitudinal planes, sniffing and extended head positions, and nil and firm transducer pressures. The primary outcome was CTM depth (millimetres) measured in the transverse plane with the head extended and nil transducer pressure. Secondary outcomes included CTM depth measurements using other factor configurations. Intra-class correlation coefficients assessed the inter-observer reliability. RESULTS: CTM depth measured in the transverse plane with head extended and nil transducer pressure was significantly greater in severely obese parturients, mean 18.0 mm (95% confidence interval 16.3-19.8), vs 10.6 mm (8.81-12.4) in non-obese (P<0.001); mean difference 7.4 mm (4.9-9.9; P<0.001). CTM depths were increased in the severely obese group regardless of scanning plane, head and neck position, or transducer pressure (all P<0.001). There was excellent inter-observer reliability. CONCLUSIONS: Cricothyroid membrane depth is significantly increased in severely obese vs normal-weight parturients independently of scanning plane, head and neck position, or transducer pressure.

Cricoid Pressure During Induction for Tracheal Intubation in Critically Ill Children: A Report From National Emergency Airway Registry for Children.

OBJECTIVES: Cricoid pressure is often used to prevent regurgitation during induction and mask ventilation prior to high-risk tracheal intubation in critically ill children. Clinical data in children showing benefit are limited. Our objective was to evaluate the association between cricoid pressure use and the occurrence of regurgitation during tracheal intubation for critically ill children in PICU. DESIGN: A retrospective cohort study of a multicenter pediatric airway quality improvement registry. SETTINGS: Thirty-five PICUs within general and children's hospitals (29 in the United States, three in Canada, one in Japan, one in Singapore, and one in New Zealand). PATIENTS: Children (< 18 yr) with initial tracheal intubation using direct laryngoscopy in PICUs between July 2010 and December 2015. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Multivariable logistic regression analysis was used to evaluate the association between cricoid pressure use and the occurrence of regurgitation while adjusting for underlying differences in patient and clinical care factors. Of 7,825 events, cricoid pressure was used in 1,819 (23%). Regurgitation was reported in 106 of 7,825 (1.4%) and clinical aspiration in 51 of 7,825 (0.7%). Regurgitation was reported in 35 of 1,819 (1.9%) with cricoid pressure, and 71 of 6,006 (1.2%) without cricoid pressure (unadjusted odds ratio, 1.64; 95% CI, 1.09-2.47; p = 0.018). On multivariable analysis, cricoid pressure was not associated with the occurrence of regurgitation after adjusting for patient, practice, and known regurgitation risk factors (adjusted odds ratio, 1.57; 95% CI, 0.99-2.47; p = 0.054). A sensitivity analysis in propensity score-matched cohorts showed cricoid pressure was associated with a higher regurgitation rate (adjusted odds ratio, 1.01; 95% CI, 1.00-1.02; p = 0.036). CONCLUSIONS: Cricoid pressure during induction and mask ventilation before tracheal intubation in the current ICU practice was not associated with a lower regurgitation rate after adjusting for previously reported confounders. Further studies are needed to determine whether cricoid pressure for specific indication with proper maneuver would be effective in reducing regurgitation events.

A human model of restricted upper esophageal sphincter opening and its pharyngeal and UES deglutitive pressure phenomena.

Oropharyngeal dysphagia due to upper esophageal sphincter (UES) dysfunction is commonly encountered in the clinical setting. Selective experimental perturbation of various components of the deglutitive apparatus can provide an opportunity to improve our understanding of the swallowing physiology and pathophysiology. The aim is to characterize the pharyngeal and UES deglutitive pressure phenomena in an experimentally induced restriction of UES opening in humans. We studied 14 volunteers without any dysphagic symptoms (7 men, 66 ± 11 yr) but with various supraesophageal reflux symptoms. To induce UES restriction, we used a handmade device that with adjustment could selectively apply 0, 20, 30, or 40 mmHg pressure perpendicularly to the cricoid cartilage. Deglutitive pharyngeal and UES pressure phenomena were determined during dry and 5- and 10-ml water swallows × 3 for each of the UES perturbations. External cricoid pressure against the UES resulted in a significant increase in hypopharyngeal intrabolus pressure and UES nadir deglutitive relaxation pressure for all tested swallowed volumes (P < 0.05). Application of external cricoid pressure increased the length of the UES high pressure zone from 2.5 ± 0.2 to 3.1 ± 0.2, 3.5 ± 0.1, and 3.7 ± 0.1 cm for 20, 30, and 40 mmHg cricoid pressure, respectively (P < 0.05). External cricoid pressure had no significant effect on pharyngeal peristalsis. On the other hand, irrespective of external cricoid pressure deglutitive velopharyngeal contractile integral progressively increased with increased swallowed volumes (P < 0.05). In conclusion, acute experimental restriction of UES opening by external cricoid pressure manifests the pressure characteristics of increased resistance to UES transsphincteric flow observed clinically without affecting the pharyngeal peristaltic contractile function.

Mechanical Modeling of the Human Cricoid Cartilage Using Computer-Aided Design: Applications in Airway Balloon Dilation Research.

OBJECTIVES: Balloon dilation is generally considered first-line treatment for airway stenosis. Some dilation systems utilize a compliant balloon that can conform around rigid structures. Others use a noncompliant balloon that does not conform, allowing for dilation of more rigid stenoses. We hypothesized that subglottic dilation with a noncompliant balloon increases the likelihood of fracture of the cricoid when compared to a compliant balloon. METHODS: Three fresh human cricoid cartilages were placed in a universal testing system to determine the expansile force necessary for cricoid fracture. Using these data, a 3D printer was used to construct a synthetic cricoid model possessing near identical physical characteristics to the human cricoid. Simulated dilation was then performed on the model using a compliant and a noncompliant balloon. RESULTS: Human cricoid fracture occurred at 97.25 N (SD = 8.34), and the synthetic cricoid model fractured at 100.10 N (SD = 7.32). Both balloons fractured the model in every replicate experiment. Mean balloon internal pressure at fracture was 7.67 ATM (SD = 1.21) for the compliant balloon and 11.34 ATM (SD = 1.29) for the noncompliant balloon. CONCLUSIONS: These data show that fracture of the cricoid is a valid concern in balloon dilation procedures where the balloon spans the subglottis. Furthermore, the hypothesis was rejected in that the compliant balloon system was at least as likely to fracture the cricoid model as the noncompliant.

Analysis of Cricoid Pressure Force and Technique Among Anesthesiologists, Nurse Anesthetists, and Registered Nurses.

PURPOSE: The purpose of this project was to assess the ability of anesthesiologists, nurse anesthetists, and registered nurses to correctly identify anatomic landmarks of cricoid pressure and apply the correct amount of force. DESIGN: The project included an educational intervention with one group pretest-post-test design. METHODS: Participants demonstrated cricoid pressure on a laryngotracheal model. After an educational intervention video, participants were asked to repeat cricoid pressure on the model. FINDINGS: Participants with a nurse anesthesia background applied more appropriate force pretest than other participants; however, post-test results, while improved, showed no significant difference among providers. Participant identification of the correct anatomy of the cricoid cartilage and application of correct force were significantly improved after education. CONCLUSION: This study revealed that participants lacked prior knowledge of correct cricoid anatomy and pressure as well as the ability to apply correct force to the laryngotracheal model before an educational intervention. The intervention used in this study proved successful in educating health care providers.

Acoustic study of pharyngeal swallowing as a function of the volume and consistency of the bolus.

Cervical auscultation is a noninvasive technique for the exploration of swallowing and has been used since the 1960s. The aim of our study was to describe how the volume and consistency of the bolus affect swallowing acoustic sound characteristics in healthy subjects. Twenty-three subjects aged from 20 to 59 years were included (13 women and 10 men). A microphone mounted on a stethoscope chest piece, positioned on the skin on the right side in front of the posteroinferior border of the cricoid cartilage, was used; it was connected to a computer for acoustic recordings. Each subject swallowed 2-, 5-, and 10-ml aliquots of water, yogurt, and mashed potato. Each bolus was administered once, with a period of at least 30 s between each swallow. For each recorded sound, the total duration of the sound and the duration of each sound component (SC) (SC1, SC2, and SC3) and interval (IT1 and IT2) between the SCs were measured. For all records, the average duration of acoustic measures was calculated. Differences according to the volume and the consistency of the swallowed bolus were assessed using Student's t test for paired data. We calculated the percentage of recordings that included each SC. We also compared results between men and women using Student's t test. We successfully interpreted 540 of the 621 (87 %) records. The results indicated that the average total duration of the sound, and especially the average duration of SC2, increased with increasing volume and was greater for mashed potato than for the boluses of other consistencies. SC2 was present in all of the records.

The effect of different catheter balloon dilatation modes on cricopharyngeal dysfunction in patients with dysphagia.

The primary aim of this study was to investigate the outcomes of two different modes (active and passive) of balloon dilatation therapy on cricopharyngeal dysfunction (CPD). Thirty-eight CPD patients with neurological disorders were recruited between 2006 and 2010. Twenty-one of them received active balloon dilatation therapy, and the remaining 17 received passive dilatation therapy for an average of 4 weeks. The patients' swallowing function before and after the intervention was evaluated using the Functional Oral Intake Scale (FOIS) and the upper esophageal sphincter (UES) opening was studied with the videofluoroscopic swallow study. Both modes of balloon dilatation therapy yielded improvements in the FOIS (active group: z = -3.767, p < 0.001; passive group: z = -3.472, p < 0.001) and the UES opening (both groups: p < 0.01). Active dilatation showed a significantly better FOIS result (p = 0.028) than passive dilatation for CPD. Both active and passive balloon dilatation benefits patients with neurological disorders but active balloon dilatation is better.

Quantitative classification of pediatric swallowing through accelerometry.

BACKGROUND: Dysphagia or swallowing disorder negatively impacts a child's health and development. The gold standard of dysphagia detection is videofluoroscopy which exposes the child to ionizing radiation, and requires specialized clinical expertise and expensive institutionally-based equipment, precluding day-to-day and repeated assessment of fluctuating swallowing function. Swallowing accelerometry is the non-invasive measurement of cervical vibrations during swallowing and may provide a portable and cost-effective bedside alternative. In particular, dual-axis swallowing accelerometry has demonstrated screening potential in older persons with neurogenic dysphagia, but the technique has not been evaluated in the pediatric population. METHODS: In this study, dual-axis accelerometric signals were collected simultaneous to videofluoroscopic records from 29 pediatric participants (age 6.8 ± 4.8 years; 20 males) previously diagnosed with neurogenic dysphagia. Participants swallowed 3-5 sips of barium-coated boluses of different consistencies (normally, from thick puree to thin liquid) by spoon or bottle. Videofluoroscopic records were reviewed retrospectively by a clinical expert to extract swallow timings and ratings. The dual-axis acceleration signals corresponding to each identified swallow were pre-processed, segmented and trimmed prior to feature extraction from time, frequency, time-frequency and information theoretic domains. Feature space dimensionality was reduced via principal components. RESULTS: Using 8-fold cross-validation, 16-17 dimensions and a support vector machine classifier with an RBF kernel, an adjusted accuracy of 89.6% ± 0.9 was achieved for the discrimination between swallows with and with out airway entry. CONCLUSIONS: Our results suggest that dual-axis accelerometry has merit in the non-invasive detection of unsafe swallows in children and deserves further consideration as a pediatric medical device.

Laryngotracheal stenosis and restenosis. What has the influence on the final outcome?

The aim of this study is to analyze the impact of various parameters on the course and treatment outcome in patients with laryngotracheal stenosis and recurrent stenosis. Two groups of patients were compared: Group I included 29 patients with primary stenosis, and Group II included 22 patients with recurrent stenosis. The most frequent etiological factor for the development of stenosis was prolonged endotracheal intubation (79.3:77.3%), with subglottic-tracheal (44.8:45.5%) and tracheal (48.3:36.4%) localization being the most affected. Subglottic-tracheal stenosis was more common in men. There were no significant differences between the groups in regard to the grade of lumen obstruction and the length of the resected segment. In male patients, the length of the resected stenotic segment was significantly longer. Subglottic-tracheal stenoses were longer than tracheal ones. Various surgical procedures were performed, with additional management of recurrent laryngeal nerve paralysis, if necessary. Laryngotracheal reconstruction (LTR) with costal cartilage grafting (CCG) was statistically significantly more often performed in Group II, while cricotracheal resection (CTR) was more common in Group I. The incidence of complications in Group I was 24.1%, and in Group II it was 31.8%. Satisfactory airway lumen with undisturbed breathing was achieved in 93.1% of patients in Group I, and in 95.3% in Group II. Since the success rate was similar in both groups of the patients, it could be concluded that treatment outcome depends less on the factors associated with the stenosis, and more on adequate choice of surgical procedure and surgical team know-how.

Use of intraoperative laryngeal electromyography to evaluate stridor in children with arthrogryposis.

OBJECTIVES: Arthrogryposis is a rare, congenital condition characterized by joint contractures of the extremities with muscle weakness and fibrosis. The otolaryngological manifestations of this disorder may include stridor, chronic aspiration, and Pierre Robin sequence, among others. Prior reports of vocal fold immobility associated with arthrogryposis have attributed it to recurrent laryngeal nerve paralysis, rather than to cricoarytenoid joint restriction. The objective of this study was to determine whether children with arthrogryposis and vocal fold immobility demonstrated laryngeal electromyography (L-EMG) findings consistent with recurrent laryngeal nerve paralysis or with cricoarytenoid joint restriction. METHODS: A retrospective, institutional chart review of children with otolaryngological manifestations of arthrogryposis was performed; 6 children were identified. Three patients had vocal fold immobility documented by flexible laryngoscopy. These 3 children were prospectively evaluated with direct laryngoscopy and intraoperative L-EMG. RESULTS: The 3 children with arthrogryposis and vocal fold dysfunction had laryngoscopy-confirmed vocal fold immobility or significant restriction of motion. The intraoperative L-EMG tracings obtained from all 3 patients demonstrated motor unit action potentials without evidence of denervation. CONCLUSIONS: This series, albeit small, suggests that the vocal fold dysfunction related to arthrogryposis may be attributable to cricoarytenoid joint restriction or poor laryngeal coordination, rather than to nerve paralysis, as originally postulated.

Posterior cricoid region fluoroscopic findings: the posterior cricoid plication.

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.

A rare case report of an solitary neurofibroma in postcricoid region of hypopharynx.

RATIONALE: Postcricoid neurofibroma is an extremely rare hypopharynx tumor that can be challenging in both diagnosis and treatment. This case sheds light on the possibility of treatment with transoral microsurgery before pursuing open cervical incisions. PATIENT CONCERNS: : A 43-year-old man presented with a four months history of a persistent foreign body sensation and mild dysphagia. Indirect and direct laryngoscopy at admission revealed a round and smooth submucosal mass in the postcricoid region. DIAGNOSIS: A laryngeal enhanced computed tomography and laryngoscopy suggested that the tumor located in hypopharynx, with clear boundary and slightly strengthened edge. A supporting laryngoscopy surgery was performed under general anesthesia and a biopsy confirmed solitary neurofibroma of the postcricoid region. INTERVENTIONS: The tumor was successfully resected en bloc transorally through supporting laryngoscope, and obviated the need for open cervical surgery and tracheostomy. OUTCOMES: The patient recovered well without any intraoperative or postoperative complication and was discharged from hospital 2 days after surgery. There was no recurrence after 6 months follow-up. LESSONS: Postcricoid neurofibroma is an extremely rare hypopharynx tumor that can be diagnostically challenging. To the best of our knowledge, this is the first case reported of solitary neurofibroma originating from the postcricoid region of the hypopharynx and was surgically removed with transoral surgery through supporting laryngoscope.

Effect of cricoid force on airway calibre in children: a bronchoscopic assessment.

BACKGROUND: Cricoid pressure or to be more exact cricoid force (CF) can cause airway obstruction and subsequent difficulty with airway management during an emergency induction. METHODS: We studied 30 children with an age range of 3 months to 15 yr who presented for routine bronchoscopy or other surgical procedures requiring tracheal intubation. We looked at the effect of CF on the calibre of the subglottic airway and objectively measured the force which caused 50% or greater distortion/compression of the subglottic airway. RESULTS: There was a linear relationship between both age and weight and CF. No patient suffered any adverse effects. Overall, the mean force required to compress the airway was 10.5 N. However, this force could be as low as 5 N in children <1 yr of age, and up to between 15 and 25 N in teenagers. CONCLUSIONS: Forces well below the recommended value of 30 N will cause significant compression/distortion of the airway in a child.

Prehospital Battlefield Casualty Intervention Decision Cognitive Study.

INTRODUCTION: Airway compromise is the third most common cause of preventable battlefield death. Surgical cricothyroidotomy (SC) is recommended by Tactical Combat Casualty Care (TCCC) guidelines when basic airway maneuvers fail. This is a descriptive analysis of the decision-making process of prehospital emergency providers to perform certain airway interventions. METHODS: We conducted a scenario-based survey using two sequential video clips of an explosive injury event. The answers were used to conduct descriptive analyses and multivariable logistic regression models to estimate the association between the choice of intervention and training factors. RESULTS: There were 254 respondents in the survey, 176 (69%) of them were civilians and 78 (31%) were military personnel. Military providers were more likely to complete TCCC certification (odds ratio [OR]: 13.1; confidence interval [CI]: 6.4-26.6; P-value < 0.001). The SC was the most frequently chosen intervention after each clip (29.92% and 22.10%, respectively). TCCC-certified providers were more likely to choose SC after viewing the two clips (OR: 1.9; CI: 1.2-3.2; P-value: 0.009), even after controlling for relevant factors (OR: 2.3; CI: 1.1-4.8; P-value: 0.033). CONCLUSIONS: Military providers had a greater propensity to be certified in TCCC, which was found to increase their likelihood to choose the SC in early prehospital emergency airway management.

Cricoarytenoid Joint Ankylosis: Classification and Transoral Laser Microsurgical Treatment.

OBJECTIVE: This study aimed to describe a graduated approach for effective transoral mobilization of cricoarytenoid joint ankylosis (CJA) in the context of the Bogdasarian system of classifying posterior glottic web-based stenosis (PGWS). STUDY DESIGN: This is a retrospective cohort study through data from medical records and operative notes. A consecutive series of 23 patients who underwent reconstructive transoral laser microsurgery for PGWS with a significant degree of CJA (Bogdasarian grade III-IV) was included in the study. METHODS: Techniques necessary to remobilize their cricoarytenoid joints were reviewed in the context of the extent of scar tissue found. RESULTS: Arytenoids with CJA were successfully mobilized by resection of the fused portion of the cricoid and arytenoid cartilages achieving respiratory improvements as well as decannulation of tracheostomy-dependent patients. The majority (83%) of patient's voices improved. All patients tolerated a full diet after the procedures. Cases with Bogdasarian grade III PGWS with minor unilateral fixation should be classified as IIIa. If the fixation is severe, the case should be classified as a grade IIIb. Grade IVa would indicate that both sides were mildly to moderately ankylosed, and grade IVb involves ankylosis of both joints with subtotal or complete fusion of at least one; it presents the greatest surgical challenge. CONCLUSION: We provided effective transoral techniques for the re-mobilization of cricoarytenoid joint, along with a classification of CJA that aims to standardize the severity of disease in the context of the existing and widely accepted Bogdasarian scale.

Quantitative Measurement of the Three-dimensional Structure of the Vocal Folds and Its Application in Identifying the Type of Cricoarytenoid Joint Dislocation.

OBJECTIVE: The objective of this study was to quantitatively measure the three-dimensional (3D) structure of the vocal folds in normal subjects and in patients with different types of cricoarytenoid dislocation. We will analyze differences in parameters between the groups and also determine if any morphologic parameters possess utility in distinguishing the type and the degree of cricoarytenoid dislocation. STUDY DESIGN: This retrospective study was conducted using university hospital data. METHODS: Subjects' larynges were scanned using dual-source computed tomography (CT). The normal subjects were divided into deep-inhalation and phonation groups, and patients with cricoarytenoid joint dislocation were divided into anterior-dislocation and posterior-dislocation groups. Membranous vocal fold length and width were measured directly on the thin-section CT images. Vocal fold and airway 3D models were constructed using Mimics software and used in combination to measure vocal fold thickness, subglottal convergence angle, and oblique angle of the vocal folds. RESULTS: The phonation group displayed a greater vocal fold width, greater oblique angle, thinner vocal folds, and a smaller subglottal convergence angle than those of the deep-inhalation group (P < 0.05). The anterior-dislocation group displayed a smaller oblique angle and subglottal convergence angle than the posterior-dislocation group (P < 0.05). CONCLUSIONS: The 3D structure of the vocal folds during deep inhalation and phonation can be accurately measured using dual-source CT and laryngeal 3D reconstruction. As the anterior-dislocation group yielded negative values for the oblique angle and the posterior-dislocation group yielded positive values, the oblique angle of the vocal folds may possess utility for distinguishing the type and for quantitatively determining the degree of cricoarytenoid dislocation.

On the development of idiopathic subglottic stenosis.

Idiopathic subglottic stenosis is a fibrotic narrowing of the airway at the level of the cricoid cartilage, which can result in severe dyspnea. There is an overwhelming female preponderance, and treatment usually involves dilation, tracheostomy or resection with reconstruction of the involved portion of the airway. The exact mechanism of action is unknown. Estrogen has been thought to play a role in the pathogenesis of this disease, but estrogen receptors have not been found in tissue specimens taken from afflicted individuals. A careful history taken from the patient often reveals a severe episode of coughing prior to the development of symptoms, and intraoperative examination can reveal impaction of the first tracheal ring within the lumen of the cricoid cartilage. Based on these observations, we surmise that an intermittent telescoping effect of the first tracheal ring within the lumen of the cricoid cartilage can lead to disruption of the local blood supply and trauma to the cricoid mucosa, with consequent mucosal edema, ischemia, and ultimately fibrosis. While estrogen has been shown to play a beneficial role in wound healing, abnormal wound healing may be potentiated by variations in estrogen receptor expression, and could also explain the female preponderance seen in this disease.