Upper airway in children with unilateral cleft lip and palate evaluated with computational fluid dynamics.

INTRODUCTION: Children with unilateral cleft lip and palate (UCLP) exhibit snoring and mouth breathing. They are also reported to show obstructive sleep apnea syndrome. However, their upper airway ventilation condition is not clearly understood. Therefore, this study was performed to evaluate upper airway ventilation condition in children with UCLP with the use of computational fluid dynamics. METHODS: Twenty-one children (12 boys, 9 girls; mean age 9.1 years) with UCLP and 25 children (13 boys, 12 girls; mean age 9.2 years) without UCLP who required orthodontic treatment underwent cone-beam computed tomography (CBCT). Nasal resistance and upper airway ventilation condition were evaluated with the use of computational fluid dynamics from CBCT data. The groups were compared with the use of Mann-Whitney U tests and Student t tests. RESULTS: Nasal resistance of the UCLP group (0.97 Pa/cm3/s) was significantly higher than that of the control group (0.26 Pa/cm3/s; P < 0.001). Maximal pressure of the upper airway (335.02 Pa) was significantly higher in the UCLP group than in the control group (67.57 Pa; P < 0.001). Pharyngeal airway (from choanae to base of epiglottis) pressure in the UCLP group (140.46 Pa) was significantly higher than in the control group (15.92 Pa; P < 0.02). CONCLUSIONS: Upper airway obstruction in children with UCLP resulted from both nasal and pharyngeal airway effects.

Radiologic indicators for prediction of difficult laryngoscopy in patients with cervical spondylosis.

BACKGROUND: We identified the most useful variables for prediction of difficult laryngoscopy in patients with cervical spondylosis according to physical indicators and preoperative skeletal X-ray and soft tissue MRI measurements. We hypothesized that there was a closer association between difficult laryngoscopy and radiologic indicators. METHODS: We randomly enroled 315 patients undergoing elective cervical spine surgery and analysed the radiological and physical data in predicting difficult laryngoscopy. RESULTS: We identified five variables that were most useful in predicting difficult laryngoscopy: the inter-incisor gap (P = 0.006), modified Mallampati test score (P = 0.004), distance from the highest point of the hyoid bone to the mandibular body (P < 0.001), most antero-inferior point of the upper central incisor tooth (P < 0.001), and length of the epiglottis (P = 0.002). Binary multivariate logistic regression analyses identified three factors that were independently associated with difficult laryngoscopy: the Mallampati score, distance from the hyoid bone to the mandibular body, and the anterior-inferior point of the upper central incisor tooth. The odds ratios and 95% confidence intervals were 1.547 (1.029-2.327), 1.222 (1.139-1.310), and 1.224 (1.133-1.322), respectively. The AUC for hyoid bone distance to mandibular body (0.832) was larger than that of anterior-inferior point of the upper central incisor tooth (0.802, P > 0.05) and that of modified Mallampati test (0.602, P < 0.05). CONCLUSION: Distance from the highest point of the hyoid bone to the mandibular body appears to be the most accurate indicator for difficult laryngoscopy in patients with cervical spondylosis.

Surface anatomy of major anatomical landmarks of the neck in an adult population: A Ct Evaluation of Vertebral Level.

To compare the projectional surface anatomy of healthy individuals in an adult population with those with a thyroid mass, using computed tomography (CT). Sixteen slice CT images of 101 individuals were analyzed using a 32-bit Radiant DICOM viewer to establish the relationships among major anatomical landmarks in the neck and their vertebral levels. The structures investigated included: hard palate (HP), hyoid bone (HB) including body and lesser horns, soft palate (SP), thyroid gland (TG) (both superior and inferior poles), thyroid gland anteroposterior (APD) and superoinferior (SID) diameters, thyroid isthmus (TI) superoinferior dimension, epiglottis, vertebral arteries (right and left), and both right and left parotid glands (superior and inferior extents). The vertebral levels noted most frequently were: body of hyoid bone (C4, 42.71%); lesser horns of hyoid bone (C3, 36.46%); thyroid gland superior pole (C6, 31.25%); and thyroid gland inferior pole (T2, 30.2%). TG-ID, TG-APD, and TG-SID were not significantly different between males and females in the healthy group; however, there was a significant gender difference in thyroid gland inferior diameter in the pathology group [males 2.16(±1.16) vs. females 3.37(±1.30), P = 0.01, paired sample t-test]. Further studies are needed to determine whether neck pathology in those with a thyroid mass affects the dimensions of the thyroid gland. Moreover, the surface anatomy of the neck should be revisited using modern imaging techniques to address inconsistencies in anatomy and clinical reference texts. Clin. Anat. 30:781-787, 2017. © 2017Wiley Periodicals, Inc.

Effect of a neck collar on upper airway size in children sedated with propofol-midazolam combination during magnetic resonance imaging.

INTRODUCTION: Propofol and midazolam are widely used for pediatric magnetic resonance imaging (MRI) sedation. Increasing depth of sedation may be associated with airway obstruction. A neck collar supporting the mandible and maintaining the head in slight extension may be beneficial in maintaining airway patency. AIM OF THE STUDY: Primary aim: To assess upper airway size with and without a neck collar during pediatric MRI sedation with propofol-midazolam. Secondary aim: To evaluate complications encountered during the procedure. MATERIALS AND METHODS: Sixty patients aged 2-4 years scheduled for MRI of the brain were selected. They were sedated with intramuscular midazolam 0.1 mg·kg(-1) 30 min before the procedure. Patients were sedated with i.v. propofol 1 mg·kg(-1) and continued with 50-100 µg·kg(-1) ·min(-1) . T1 3D fast-field echo axial sequence from the nasopharyngeal roof to subglottic region was taken with and without application of a neck collar. Airway dimensions were measured and analyzed at the base of the tongue, soft palate, and at the epiglottis. RESULTS: At the base of the tongue and soft palate, the cross-sectional area (CSA) and the anteroposterior diameter of the airway were respectively statistically significantly higher when the neck collar was applied. The CSA at the epiglottis was significantly less with application of the neck collar. Complications were not significantly different between the two sequences. CONCLUSION: Application of a soft neck collar in children aged 2-4 years may enhance the retropalatal and retroglossal airway dimensions during pediatric sedation in the supine position.

Tongue Size and Posterior Airway Space Changes in Class III Malocclusion After Maxillomandibular Surgery: A Retrospective Study.

The purpose of this study was to evaluate the changes in the airway space after surgical correction of Class III skeletal dentofacial deformity and to determine if orthognathic surgery alters the airway space and improves obstructive sleep apnea. Twenty-four Class III adults treated with orthognathic surgery were divided into two groups as Mandibular set-back (Bilateral Sagittal Split Osteotomy-BSSO, 10 patients) and two jaw surgery (Bilateral Sagittal Split Osteotomy combined with Le Fort I maxillary advancement, 14 patients). Lateral cephalometric radiographs were traced before (T0) and 6 months after surgery (T1). Steiner and McNamara analysis, linear pharyngeal airway measurements (PNS-PPW1, SPT-PPW2, E-PPW3, PNS-SPT), tongue volume measurements (TH, Tt-Eb) and pharyngeal area measurements (nasopharyngeal, upper oropharyngeal, lower oropharyngeal, epiglottis area) were performed. The data obtained was analyzed statistically by repeated measurement ANOVA and Duncan's test. The increase of PNS-PPW1 was important in two jaw surgery group (p < 0.05). The nasopharyngeal area was statistically different between T0 and T1 (p < 0.01), and the lower oropharyngeal area was statistically significant between BSSO and two jaw surgery groups (p < 0.05). Surgical correction of Class III skeletal dentofacial deformity alters posterior airway dimensions. Two jaw surgery is advantageous considering the risk for obstructive sleep apnea, because it evokes an increase in the upper pharyngeal airway dimensions. Keywords: Tongue size, posterior airway space, maxillomandibular surgery.

Degrees of reality: airway anatomy of high-fidelity human patient simulators and airway trainers.

BACKGROUND: Human patient simulators and airway training manikins are widely used to train airway management skills to medical professionals. Furthermore, these patient simulators are employed as standardized "patients" to evaluate airway devices. However, little is known about how realistic these patient simulators and airway-training manikins really are. This trial aimed to evaluate the upper airway anatomy of four high-fidelity patient simulators and two airway trainers in comparison with actual patients by means of radiographic measurements. The volume of the pharyngeal airspace was the primary outcome parameter. METHODS: Computed tomography scans of 20 adult trauma patients without head or neck injuries were compared with computed tomography scans of four high-fidelity patient simulators and two airway trainers. By using 14 predefined distances, two cross-sectional areas and three volume parameters of the upper airway, the manikins' similarity to a human patient was assessed. RESULTS: The pharyngeal airspace of all manikins differed significantly from the patients' pharyngeal airspace. The HPS Human Patient Simulator (METI®, Sarasota, FL) was the most realistic high-fidelity patient simulator (6/19 [32%] of all parameters were within the 95% CI of human airway measurements). CONCLUSION: The airway anatomy of four high-fidelity patient simulators and two airway trainers does not reflect the upper airway anatomy of actual patients. This finding may impact airway training and confound comparative airway device studies.

Estimation of the nares-to-epiglottis distance and the nares-to-vocal cords distance in young children.

BACKGROUND: Estimation of the nares-to-epiglottis and nares-to-vocal cords distances would facilitate the selection of properly sized nasopharyngeal airways and appropriate positioning of a fibreoptic bronchoscope in young children. The purposes of this study were to measure the nares-to-epiglottis and nares-to-vocal cords distances and to create an algorithm to predict these distances based on anatomical landmarks and paediatric characteristic data. METHODS: Two hundred and eleven children, aged 1-10 yr, undergoing elective surgery were investigated. After induction of general anaesthesia, the distances from the nares to the epiglottis/vocal cords were measured using a nasogastric tube. After intubation, the distances from the lateral border of the nose to the ipsilateral mandible angle (nares-to-mandible distance) and the tragus of the ear (nares-to-tragus distance) were measured using a tape measure. RESULTS: The nares-to-epiglottis and nares-to-vocal cords distances were significantly correlated with the age, weight, height, and external measurements (P<0.001). By stepwise multiple linear regression analysis, formulas were obtained for the nares-to-epiglottis distance (cm)=2.606+0.058×height (cm)+0.231×the nares-to-mandible distance (cm)-0.304 (gender) (r(2)=0.754) and for the nares-to-vocal cords distance (cm)=4.947+0.06×height (cm)+0.228×nares-to-mandible distance (cm)-0.283 (gender) (r(2)=0.803). CONCLUSIONS: The nares-to-epiglottis and nares-to-vocal cords distances can be predicted using the height and the nares-to-mandible distance in young children. CLINICAL TRIAL REGISTRATION NUMBER: Clinical Research Information Service KCT0000150.

A clinical evaluation of the I-gel ™ supraglottic airway device in children.

BACKGROUND: The i-gel(TM) is one of the latest commercially available, second-generation supraglottic airway devices (SADs). Specific features include a distal cuff made of a thermoplastic elastomer gel that does not require inflation and a gastric side channel to allow passage of a gastric tube, venting of gas from the stomach, and an early indication of regurgitation. Previous studies in older children and adults have shown that it is a reliable, efficient, and safe device for airway management. METHODS: We evaluated the i-gel(TM) in sizes ranging from 1 to 2.5 in children considered suitable for a supraglottic device. We assessed successful rates of insertion, airway leak pressure, position confirmed by fiberoptic laryngoscopy, gastric tube placement, manipulations required, and complications. RESULTS: The i-gel(TM) was used in 154 children over a period of 12 months. The median age [interquartile range (IQR)] was 4 years 11 months (2-7 years), median weight (IQR) 19 kg (13-26), and median (IQR) duration of procedure 29 (30-45) min. First insertion attempt was successful in 93.5% of patients, and second attempt in 5.8%. The median (IQR) time to insertion was 14 (13-16) s. The median (IQR) leak pressure was 20 (15-25) cmH(2) 0. Gastric tube placement was successful in 90% of cases. On fiberoptic examination, the vocal cords were visible in 97% of patients. Complications arose in 20% of patients, but the majority were minor. Anesthetists commented that the device had a tendency to displace upward out of the mouth and that extension toward the forehead and flexion toward the feet of the proximal tube altered the quality of the airway. Overall, in seven (4.5%) patients, the device was abandoned and an alternative airway was used. CONCLUSIONS: Pediatric i-gel(TM) sizes 1.5-2.5 provided a satisfactory airway during anesthesia for spontaneously breathing infants and children. However, to ensure a clear airway, considerable vigilance is required when fixing the device in the mouth and to avoid the negative effects of flexion of the proximal tubing. The i-gel(TM) is more expensive than first-generation devices. Whether this additional cost for the potential benefit of greater airway protection is considered acceptable will depend on longer-time evaluation and surveillance to establish overall safety.

Three-dimensional analysis of the pharyngeal airway morphology in growing Japanese girls with and without cleft lip and palate.

INTRODUCTION: We evaluated the 3-dimensional craniofacial skeletal and pharyngeal airway morphology in growing patients with and without cleft lip and palate. METHODS: Our juvenile subjects consisted of 34 girls (ages, 9-12 years); 15 had cleft lip and palate, and 19 did not. The adolescent subjects consisted of 32 girls (ages, 13-17 years); 14 had cleft lip and palate, and 18 did not. Each subject was examined with cone-beam computed tomography. The dimensions of the craniofacial skeleton and pharyngeal airway were measured. The Scheffé method of multiple comparisons was used to identify relationships among skeletal and pharyngeal variables. RESULTS: The pharyngeal airway and mandibular size variables did not differ significantly between the juvenile and adolescent cleft lip and palate groups. Significant differences were observed between each cleft lip and palate group and its corresponding control group. FHN-A, FHN-B, FH-NA, FH-NB, and Co-Me were significantly smaller in the cleft lip and palate groups than in the corresponding control groups. Anteroposterior and lateral widths, heights, and volumes of the superior oropharyngeal airway were significantly smaller in the adolescent cleft lip and palate group than in the adolescent controls. CONCLUSIONS: The mandible and the oropharyngeal airway were larger in the adolescent controls than in the juvenile controls without cleft lip and palate, but there were no significant differences between the adolescent and juvenile patients with cleft lip and palate.

Stability of pharyngeal airway dimensions: tongue and hyoid changes after treatment with a functional appliance.

UNLABELLED: Because stability is known as the fundamental key of the successful outcome of orthodontics treatment, this study investigated the stability of tongue, hyoid bone and airway dimensions at least two years after active treatment with Faramand functional appliance in patients with class II div 1 malocclusion. CONCLUSION: The present findings indicate that treatment with functional appliance has the potential to increase pharyngeal airway dimensions and changes in tongue and hyoid position. Importantly, these achieved changes seemed to be maintained in long-term, up to 4 years on average.

Optimal degree of mouth opening for laryngeal mask airway function during oral surgery.

PURPOSE: This study was performed to determine the optimal degree of mouth opening in anesthetized patients requiring laryngeal mask airway (LMA) during oral surgery. PATIENTS AND METHODS: A single, experienced LMA user inserted the LMA in 15 patients who were scheduled for elective oral surgery. Oropharyngeal leak pressure, intracuff pressure, and fiberoptic assessment of the LMA position were sequentially documented in 5 mouth conditions-opening of 1.4 (neutral position), 2, 3, 4, and 5 cm-and any resulting ventilatory difficulties were recorded. RESULTS: Oropharyngeal leak pressure with the mouth open 4 cm (21.8 ± 3.2 cm H(2)O, P = .025) and 5 cm (27.3 ± 7.2 cm H(2)O, P < .001) was significantly higher than in the neutral position (18.1 ± 1.5 cm H(2)O), as was intracuff pressure (neutral position, 60.0 ± 0 cm H(2)O; 4 cm, 72.6 ± 5.1 cm H(2)O [P < .001]; and 5 cm, 86.9 ± 14.4 cm H(2)O [P < .001]). LMA position, observed by fiberoptic bronchoscopy, was unchanged by mouth opening, being similar in the 5 mouth conditions (P = .999). In addition, ventilation difficulties (abnormal capnograph curves or inadequate tidal volume) occurred in 2 of 15 patients (13%) and 7 of 15 patients (53%) (P < .001) with the mouth opening of 4 and 5 cm, respectively. CONCLUSIONS: This study showed that a mouth opening over 4 cm led to substantial increases in oropharyngeal leak pressure and intracuff pressure of the LMA, warranting caution, because gastric insufflation, sore throat, and ventilation difficulties may occur. A mouth opening of 3 cm achieves acceptable airway conditions for anesthetized patients requiring LMA.

The influence of mouth opening on oropharyngeal leak pressure, intracuff pressure, and cuff position with the laryngeal mask airway.

PURPOSE: The aim of this study was to investigate the influence of mouth opening on oropharyngeal leak pressure, intracuff pressure, and cuff position of the laryngeal mask airway (LMA). PATIENTS AND METHODS: Fifteen patients who were scheduled for elective oral surgery were recruited into this study. A single, experienced LMA user inserted the LMA according to the manufacturer's recommended technique. Oropharyngeal leak pressure, intracuff pressure, and fiberoptic assessment of the LMA position were documented under 3 mouth conditions: neutral position (1.4-cm distance between upper and lower incisors), mouth open (5- to 6-cm distance between upper and lower incisors), and return to the neutral position. Any ventilation difficulties under the 3 mouth conditions were recorded. RESULTS: Oropharyngeal leak pressure with the mouth open was higher than in the neutral position (P < .001). Compared with the neutral position, intracuff pressure was also higher with the mouth open (P < .001). Both measurement values returned to control levels when the neutral position was once again assumed. The LMA position observed by fiberoptic bronchoscopy was unchanged by mouth opening and was similar in the 3 mouth conditions (P = .998). Although ventilatory difficulties occurred after mouth opening in 8 of 15 patients (P < .001), it did not occur when the neutral position was reassumed. CONCLUSIONS: This study showed that mouth opening led to substantial increases in oropharyngeal leak pressure and intracuff pressure of the LMA, warranting caution because gastric insufflation, sore throat, and ventilation difficulties may occur.

Combining the EndoFlex tube with fiberoptic bronchoscopy in difficult intubation.

We applied a combination technique using the EndoFlex tube with fiberoptic bronchoscopy for a 69-year-old man presenting with limited mouth opening and neck movement. Awake nasotracheal intubation was performed under conscious sedation with propofol and fentanyl. After positioning the tip of the EndoFlex tube in the oropharynx, the fiberoptic bronchoscope was inserted into the tube until the tip reached the bevel of the tube. Anterior flexion of the distal tip of the EndoFlex tube facilitated uncomplicated insertion of the tube into the trachea without impingement on the arytenoids. Fiberoptic visualization confirmed that the distal-tip flexing mechanism of the EndoFlex tube corrected the direction of the tube tip anteriorly, allowing entry into the trachea. We present a case where this technique proved valuable for tracheal intubation in a patient with limitations of mouth opening and neck movement.

Estimation of nares-to-epiglottis distance for selecting an appropriate nasopharyngeal airway.

The nasopharyngeal airway is an important equipment in airway management, a correct placement is crucial for its effectiveness. We measured the nares-to-epiglottis distance (NED) and examined the correlations of the optimal insertion length (NED-1) with patient characteristics and various external facial measurements. We aimed to develop a simple method for estimating the optimal insertion length and to help select an appropriate nasopharyngeal airway.Two hundred patients of ASA grade I & II aged >20 years undergoing elective surgery under general anesthesia were enrolled. We measured nares-to-ear tragus distance (NTD), nares-to-mandibular angle distance (NMD), philtrum-to-ear tragus distance (PTD), and philtrum-to-mandibular angle distance (PMD). The NED was measured by fiber-optic bronchoscope. All measurements were obtained in centimeters. NED-1 (cm) was defined as the optimal insertion length. The patient's sex, age, body weight, body height, and body mass index were recorded.The NED-1 significantly correlated with body weight, body height, NTD, NMD, PTD, and PMD. Backward stepwise multiple linear regression analysis yielded the formula for predicting NED-1: 0.331 - 0.018 × BW + 0.061 × BH + 1.080 × NMD - 1.256 × PMD + 0.697 × PTD (r = 0.640, P < .001). The regression lines of the optimal insertion length versus PTD showed the best fit to the equality line. The measurements of PTD showed the minimal differences from NED-1 and with the most patients showing <1 cm differences from NED-1.The optimal insertion depth of nasopharyngeal airway can easily be predicted by the distance from philtrum-to-ear tragus, and a nasopharyngeal airway of an appropriate size can be selected accordingly.

The nasopharyngeal airway: Estimation of the nares-to-mandible and nares-to-tragus distance in young children to assess current clinical practice.

BACKGROUND: Nasopharygeal airways are used in urgent situations to alleviate airway obstruction. Guidelines for measuring the length of the NPA differ between national and international guidelines, and the evidence base for these measurements is lacking. The purpose of this study was to measure the nares-epiglottis and nares-vocal cord distances in young children (neonates to 12 years) on 3D reconstructed Magnetic Resonance Imaging (MRI) brain volume scans, and to examine the relationship of these distances with the nares-tragus and nares-mandible distances. METHOD: One-hundred and seventy-six scans were reviewed. All patients had undergone MRI 3D brain volume imaging. The anatomical landmarks were identified and the nares-tragus, nares-mandible distances measured and compared to nares-epiglottis and nares-vocal cord distance using Osirix. RESULTS: The nares-epiglottis and nares-vocal cords distances significantly correlated (p-value <0.05). The nares-tragus distance showed strong correlation with the nares-epiglottis and nares-vocal cord distance compared to the nares-mandible distance (p-value <0.05). CONCLUSION: In conclusion, the length of a nasopharyngeal airway in children under the age of twelve years can be predicted using the nares-tragus external anatomical distance minus 10 mm.

Development of the supralaryngeal vocal tract in Japanese macaques: implications for the evolution of the descent of the larynx.

The configuration of the supralaryngeal vocal tract depends on the nonuniform growth of the oral and pharyngeal portion. The human pharynx develops to form a unique configuration, with the epiglottis losing contact with the velum. This configuration develops from the great descent of the larynx relative to the palate, which is accomplished through both the descent of the laryngeal skeleton relative to the hyoid and the descent of the hyoid relative to the palate. Chimpanzees show both processes of laryngeal descent, as in humans, but the evolutionary path before the divergence of the human and chimpanzee lineages is unclear. The development of laryngeal descent in six living Japanese macaque monkeys, Macaca fuscata, was examined monthly during the first three years of life using magnetic resonance imaging, to delineate the present or absence of these two processes and their contributions to the development of the pharyngeal topology. The macaque shows descent of the hyoid relative to the palate, but lacks the descent of the laryngeal skeleton relative to the hyoid and that of the EG from the VL. We argue that the former descent is simply a morphological consequence of mandibular growth and that the latter pair of descents arose in a common ancestor of extant hominoids. Thus, the evolutionary path of the great descent of the larynx is likely to be explained by a model comprising multiple and mosaic evolutionary pathways, wherein these developmental phenomena may have contributed secondarily to the faculty of speech in the human lineage.

Can facial type be used to predict changes in hyoid bone position with age? A perspective based on longitudinal data.

INTRODUCTION: Low positioning of the hyoid bone is associated with the unique human ability of speech, but it might also predispose the airway to collapse. The low position of the hyoid bone has been studied in adults with sleep apnea. However, information on age-related changes in hyoid bone position in the general adult population is sparse. METHODS: We used pairs of lateral cephalometric radiographs taken 15 years apart to assess vertical changes over time in hyoid position in 163 normal white men (ages, 30-72 years). RESULTS AND CONCLUSIONS: Significant changes in hyoid bone position were independent of age or obesity but were related to facial type, as classified by the steepness of the lower margin of the mandible. Changes in hyoid position over time were significant in dolichofacial subjects but not in brachyfacial subjects. This finding might be particularly important because a low hyoid bone with a brachial face appears to be a morphologic characteristic of nonobese patients with severe obstructive sleep apnea.

Anatomic changes after hyoid suspension for obstructive sleep apnea: an MRI study.

OBJECTIVE: To assess the effects of isolated hyoid suspension on subjective and objective parameters of obstructive sleep apnea and to evaluate changes in upper airway anatomy with the help of standardized magnetic resonance imaging. STUDY DESIGN AND SETTING: Fifteen patients received isolated hyoid suspension. Changes in respiratory disturbance index were assessed with polysomnography, and anatomical changes with standardized magnetic resonance imaging. Snoring, daytime sleepiness, and functional parameters were assessed with questionnaires. Lateral x-ray cephalometry was performed preoperatively. RESULTS: Mean respiratory disturbance index was reduced from 35.2 +/- 19.1 to 27.4 +/- 26.2. Forty percent of the patients were classified as responders. Daytime sleepiness improved significantly. Relevant changes in upper airway anatomy could not be detected. There were no remarkable differences between responders and nonresponders in regard to imaging. CONCLUSIONS: Hyoid suspension is effective only in a subgroup of patients and does not lead to relevant changes in airway diameters in the awake patient. Magnetic resonance imaging and x-ray cephalometry do not add additional information for patient selection. SIGNIFICANCE: The reported clinical effects of hyoid suspension are more likely due to functional changes in airway collapsibility than to an enlargement of the upper airway.

Effects of head and body position on two- and three-dimensional configurations of the upper airway.

This study was carried out to test the hypothesis that changes in head/body position induce changes in upper-airway dimensions. Contiguous images were obtained by means of magnetic resonance imaging in normal awake subjects during nasal breathing. A statistical analysis was made on 5 consecutive slices, including the most constricted sites in both the retropalatal and retroglossal regions. Dimensional changes in the upper airway in association with changes in head/body position were evaluated. In the retropalatal region, there was a significant decrease in the lateral dimension in the lateral recumbent position compared with that in the supine position. The cross-sectional area in the retroglossal region was significantly increased in both the "supine with the head rotated" and "lateral recumbent" positions. This change was accompanied by significant volumetric changes in the retroglossal region. Thus, sleeping with the head rotated may be effective for improving upper-airway obstruction.

Quantitative taste bud distribution in the hamster.

The distribution of taste buds was examined in hamsters to reveal the sources of convergent neural activity on taste neurons of the medulla and pons. A total of 723 taste buds was found in adult animals. Fungiform papillae contained 130 taste buds (18%). A single vallate papilla had 168 taste buds (23%). There were 230 taste buds (32%) located on bilateral foliate papillae. The palate contained 100 taste buds (14%) divided among the soft palate (88, 12%) and the incisal papilla (12, 2%). On the epiglottis and adjacent region of the esophagus were found 70 taste buds (10%). About 10 taste buds each were located on the buccal wall (1.4%), while the remaining 5 taste buds were found on the sublingual organ. Conclusions about information processing in central neurons of the gustatory system must reflect knowledge of diverse receptor populations and their interactions.