Corner vowels in males and females ages 4 to 20 years: Fundamental and F1-F4 formant frequencies.

The purpose of this study was to determine the developmental trajectory of the four corner vowels' fundamental frequency (fo) and the first four formant frequencies (F1-F4), and to assess when speaker-sex differences emerge. Five words per vowel, two of which were produced twice, were analyzed for fo and estimates of the first four formants frequencies from 190 (97 female, 93 male) typically developing speakers ages 4-20 years old. Findings revealed developmental trajectories with decreasing values of fo and formant frequencies. Sex differences in fo emerged at age 7. The decrease of fo was larger in males than females with a marked drop during puberty. Sex differences in formant frequencies appeared at the earliest age under study and varied with vowel and formant. Generally, the higher formants (F3-F4) were sensitive to sex differences. Inter- and intra-speaker variability declined with age but had somewhat different patterns, likely reflective of maturing motor control that interacts with the changing anatomy. This study reports a source of developmental normative data on fo and the first four formants in both sexes. The different developmental patterns in the first four formants and vowel-formant interactions in sex differences likely point to anatomic factors, although speech-learning phenomena cannot be discounted.

Usefulness of ultrasound-guided measurement of minimal transverse diameter of subglottic airway in determining the endotracheal tube size in children with congenital heart disease: A prospective observational study.

INTRODUCTION: The search for an accurate and predictable method to estimate the endotracheal tube (ETT) size in pediatric population had led to derivation of many formulae. Of this, age-based formulae are the most commonly used. Studies have shown that minimal transverse diameter of subglottic airway (MTDSA) measurements using a high-frequency probe improves the success rate of predicting the airway diameter to about 90%. We did a prospective observational study using MTDSA as the criteria to select the size of ETT in children with congenital heart disease. METHODS: In this prospective observational study, 51 children aged from 1 day to 5 years, scheduled for cardiac surgery, were enrolled for this study. The ETT size was guided solely based on the MTDSA. Leak test was used to determine the best-fit ETT size. RESULTS: Data from 49 patients were analyzed. Agreement between the ETT determined by MTDSA and that predicted by Cole's age-based formulas with the best-fit ETT size was analyzed using a Bland-Altman plot. CONCLUSION: Age-based formula showed poor correlation (27.5%) compared to MTDSA (87.8%) in predicting the best-fit ETT. We observed that pediatric patients with congenital heart disease need a larger sized ETT as compared to what was predicted by age-based formula. Using ultrasound MTDSA measurements to guide selection of ETT size is a safe and accurate method in pediatric cardiac population.

Pediatric upper airway dimensions using three-dimensional computed tomography imaging.

INTRODUCTION: Computed tomography- (CT) and magnetic resonance imaging (MRI)-based measurements have recently suggested that the narrowest dimension of the pediatric airway is the subglottic region. These data are contrary to the previously held tenets of a funnel- or conical-shaped airway. The current study evaluates airway volumes and shapes using three-dimensional CT images of the air way column in spontaneously breathing children. METHODS: The study included CT-based radiological images of the neck in children who required imaging unrelated to airway symptomatology. The children were evaluated during spontaneous ventilation during natural sleep or with sedation without airway devices in place. The three-dimensional images of the airway column were evaluated, volumes calculated, and comparisons made between the subglottic, cricoid, and tracheal volumes and shapes. RESULTS: The study cohort included 54 children, ranging in age from 2 months to 8 years. An increase in the airway volumes was observed from the subglottic (0.17 ± 0.06 mm3 ) to the cricoid (0.19 ± 0.06 mm3 ) to the tracheal regions (0.22 ± 0.07 mm3 ). The volumes of the subglottic, cricoid, and tracheal regions demonstrated a linear relationship with age. CONCLUSION: This study confirms recent studies demonstrating that the subglottic region not the cricoid is the narrowest part of the airway.

Measurement of glottal cycle characteristics between children and adults: physiological variations.

OBJECTIVES: The aim of this study was to quantify phases of the vibratory cycle using measurements of glottal cycle quotients and glottal cycle derivatives, in typically developing prepubertal children and young adults with the use of high-speed digital imaging (HSDI). METHODS: Vocal fold vibrations were recorded from 27 children (age range 5-9 years) and 35 adults (age range 21-45 years), with HSDI at 4000 frames per second for sustained phonation. Glottal area waveform measures of Open Quotient, Closing Quotient, Speed Index (SI), Rate Quotient, and Asymmetry Quotient (AsyQ) were computed. Glottal cycle derivatives of Amplitude Quotient (AQ) and Maximum Area Declination Rate (MADR) were also computed. Group differences (adult females, adult males, and children) were statistically investigated for mean and standard deviation values of the glottal cycle quotients and glottal cycle derivatives. RESULTS: Children exhibited higher values of SI and AsyQ and lower values of MADR compared with adult males. Children exhibited the highest mean value and lowest variability in AQ compared with adult males and females. Adult males showed lower values of SI, AsyQ, AQ, and higher values of MADR compared with adult females. CONCLUSIONS: Glottal cycle vibratory motion in children is functionally different compared with adult males and females, suggesting the need for development of children specific norms for both normal and disordered voice qualities.

Ultrasound measurement of subglottic diameter and an empirical formula for proper endotracheal tube fitting in children.

BACKGROUND: The appropriate endotracheal tube (ETT) size is commonly determined using age-based formula; ETT size determination based on ultrasound (US) measurement of subglottic diameter (SD), the narrowest portion of the paediatric upper airway, may provide a better method for accurate fit. We aimed to validate ETT size determination using US measures of SD before intubation to establish an empirical formula for ETT fitting based on SD and biographic parameters. METHODS: We included 215 children aged 1-72 months undergoing general anaesthesia. US was performed on the anterior neck to measure SD during mask ventilation under anaesthesia. Endotracheal intubation was performed with a cuffed ETT selected by age-based recommendation; the transverse outer diameter (OD) of the ETT within the trachea at the subglottis level (OD-ETT at SD) was measured. RESULTS: The OD-ETT at SD was correlated with the actual OD-ETT outside the trachea (R(2) = 0.635), showing the validity of ultrasonographic measurement; moreover, the US-measured SD revealed strong correlation with the actual OD-ETT (R(2) = 0.834). US-measured SD and biographic data (age, height and weight) showed little correlation in children less than 12 months but good correlation (age, height) in children older than 12 months (P < 0.01). CONCLUSIONS: US-measured OD-ETT at SD was in good agreement with the actual OD-ETT, suggesting that US-measured SD helps in choosing the appropriate ETT diameter for children. In children older than 12 months, the equation 'OD (mm) = 0.01 × age (months) + 0.02 × height (cm) + 3.3' may help select the appropriate ETT.

Development of the rat larynx: a histological study.

OBJECTIVES/HYPOTHESIS: To evaluate and describe the cartilaginous and muscular development of the rat larynx. STUDY DESIGN: Histologic evaluation. METHODS: The larynges of Sprague Dawley rats of embryonic day (E) 13, 15, 17, 19, 21, postnatal day 0, 14, and adult of 250 gm were collected. Four larynges of each age were harvested, cut into 15-µm serial sections, stained with hematoxylin and eosin, and evaluated under light microscopy. Representative digital images were recorded and evaluated at the preglottic (supraglottic in humans), glottic, and postglottic (subglottic in humans) levels. RESULTS: Brachial arches were observed at E13. At E17, immature structures of the larynx, including skeletal muscle, cartilage, and the lumen were identifiable. Chondrification and muscle formation were clearly seen by E19. The muscular and cartilagenous components of the larynx were well established by E21. During the span between birth and adult maturation, the size of the larynx increased from a height of 1.10 mm to 2.90 mm, and from a width of 1.80 mm to 5.40 mm, and from a length of 1.38 mm to 4.77 mm in the stained section. Although developed at E21, the laryngeal structures continued to grow by approximately 30%. CONCLUSION: Rat laryngeal development parallels that in mice and humans. In the rat, at E17 immature structures of the larynx are identifiable, they are well developed at birth and grow by approximately 30% into adulthood. Understanding the chronology and morphology of the embryogenesis of the rat laryngeal musculature is essential and will allow for further evaluation of the embryologic innervation of these muscles.

Novel measurements of the length of the subglottic airway in infants and young children.

BACKGROUND: To date, the lengths of the subglottic and tracheal airway segments have been measured from autopsy specimens. Images of the head and neck obtained from computerized tomography (CT) provide an alternate method. Our objective in this study was to identify anatomic landmarks from CT scans in infants and young children to estimate the lengths of the subglottic and tracheal airway segments and to correlate these lengths with age. METHODS: We performed a retrospective analysis of CT images of the neck for various diagnostic indications in children ≤3 years. We obtained planes of reconstruction at the level of the vocal cords (VCs), cricoid cartilage, and carina (C) which were parallel to each other and perpendicular to sagittal long axis of the trachea. The lengths of the subglottic airway (LengthSG) and total length of the laryngotracheal airway (LengthVC-C) were measured from the distance between, respectively, the VC versus cricoid cartilage and the VC versus C planes of reconstruction. Tracheal length was then calculated as the difference between LengthVC-C and LengthSG. RESULTS: Fifty-six children met the inclusion criteria. There were 29 boys. The median weight was 10.7 kg (range 3.1-19.0 kg). Regression analysis yielded mean LengthSG (mm) = 7.8 + 0.03·corrected age (months), r(2) = 0.07, P = 0.056; lower and upper 95% confidence interval for ß = 0.03 were -0.001 and 0061. The mean LengthSG was 8.4 mm with an SD of 1.4 mm. The 95th percentile for LengthSG was 10.8 mm, and the 5% to 95% interquartile range was 4.9 mm. The estimate for the 95% confidence interval of the 95th percentile was between 10.2 and 11.3 mm. The LengthVC-C increased with age: mean LengthVC-C (cm) = 5.3 + 0.05·corrected age (months), r(2) = 0.7, P < 0.001. Tracheal length also increased with age: mean tracheal length (cm) = 4.5 + 0.05·corrected age (months), r(2) = 0.6, P < 0.001. CONCLUSION: We report a novel estimate method for the lengths of the airway segments between the VC and C in 56 infants and young children and suggest that the growth characteristics of the subglottic and tracheal airway may differ.

Pediatric laryngeal dimensions: an age-based analysis.

BACKGROUND: In children, the cricoid is considered the narrowest portion of the "funnel-shaped" airway. Growth and development lead to a transition to the more cylindrical adult airway. A number of airway decisions in pediatric airway practice are based on this transition from the pediatric to the adult airway. Our primary aim in this study was to measure airway dimensions in children of various ages. The measures of the glottis and cricoid regions were used to determine whether a transition from the funnel-shaped pediatric airway to the cylindrical adult airway could be identified based on images obtained from video bronchoscopy. METHODS: One hundred thirty-five children (ASA physical status 1 or 2) aged 6 mo to 13 yr were enrolled for measurement of laryngeal dimensions, including cross-sectional area (G-CSA), anteroposterior and transverse diameters at the level of the glottis and the cricoid (C-CSA), using the video bronchoscopic technique under general anesthesia. RESULTS: Of the 135 children enrolled in the study, seven patients were excluded from the analysis mainly because of poor image quality. Of the 128 children studied (79 boys and 49 girls), mean values (+/-standard deviation) for the demographic data were age 5.9 (+/-3.3) yr, height 113.5 (+/-22.2) cm and weight 23.5 (+/-13) kg. Overall, the mean C-CSA was larger than the G-CSA (48.9 +/- 15.5 mm(2) vs 30 +/- 16.5 mm(2), respectively). This relationship was maintained throughout the study population starting from 6 mo of age (P < 0.001, r = 0.45, power = 1). The mean ratio for C-CSA: G-CSA was 2.1 +/- 1.2. There was a positive correlation between G- and the C-CSA versus age (r = 0.36, P < 0.001; r = 0.27, P = 0.001, respectively), height (r = 0.34, P < 0.001; r = 0.29, P < 0.001, respectively), and weight (r = 0.35, P < 0.001; r = 0.25, P = 0.003, respectively). No significant gender differences in the mean values of the studied variables were observed. CONCLUSION: In this study of infants and children, the glottis rather than cricoid was the narrowest portion of the pediatric airway. Similar to adults, the pediatric airway is more cylindrical than funnel shaped based on these video bronchoscopic images. Further studies are needed to determine whether these static airway measurements in anesthetized and paralyzed children reflect the dynamic characteristics of the glottis and cricoid in children.

Local control of murine subglottis development.

OBJECTIVE: To determine if subglottic development is at least partially under local control and to determine which tissue layer(s) is predominantly responsible. DESIGN: The suglottises of 12 day-3 CD1 mice were grown in whole organ culture. The 12 subglottises were divided into 3 individual groups: +++, -++, and ---. Group+++ had all tissue layers of the subglottis intact: luminal epithelium, cricoid cartilage, inner and outer perichondrium. Group-++ had all layers intact with the exception of luminal epithelium. Group--- had all layers removed (luminal epithelium, inner and outer perichondrium) resulting in cricoid cartilage-only rings. All rings were grown in basic medium without the use of growth factors or serum for 15 days. Measurements of the rings were taken before and after organ culture growth. RESULTS: Group+++ was the only group that experienced growth. Only luminal growth was statistically significant although all rings experienced growth in both the luminal and external diameter. Group-++ did not experience any growth. Group--- lost structural integrity with collapse of the ring and did not experience growth of any dimension of the cartilage. CONCLUSIONS: Growth of the subglottis is under local control but may have additional influences from the outside that were not investigated here. Removal of just the epithelium stunts growth of the entire ring, but preferentially the lumen more so than the external diameter. Removal of all tissue layers around the cricoid cartilage results in a structural collapse of the ring, suggesting that the cartilage in this age group is dependent on surrounding tissues for structural integrity.

Gross and histologic changes in the developing rabbit subglottis in response to a controlled depth of injury.

OBJECTIVE: Our goal was to determine the effects of both perichondrial and intracartilaginous injury in the developing rabbit subglottis versus normal development. DESIGN: We conducted a descriptive, pilot study of changes in the shape and histology of the subglottis after a controlled depth of injury in 27 New Zealand White rabbits, ages 4 weeks, 8 weeks, and 1(1/2) years. INTERVENTION: Within each age group, 3 animals underwent no surgery, 3 underwent perichondrial injury, and 3 underwent intracartilaginous injury. RESULTS: Perichondrially injured animals in the 4-week age group developed a marked abnormality in the shape of the cricoid cartilage in the injured region. Cartilage of the perichondriallly injured animals in the 8-week and 1(1/2)-year groups became histologically consistent with fibrous tissue. The cartilage of all animals that underwent intracartilaginous injury was replaced with fibrous tissue. CONCLUSION: In this observational study, we identified 3 relevant findings. First, the responses of the cartilage to a perichondrial injury suggest that the luminal soft tissues may exert some morphologic control in developmentally young animals. Second, only the 4-week-old group's cartilage was tolerant of a perichondrial injury with continued growth of the ring. Third, no animal's cartilage could withstand an intracartilaginous injury regardless of age.

Morphology and development of the human vocal tract: a study using magnetic resonance imaging.

Magnetic resonance imaging was used to quantify the vocal tract morphology of 129 normal humans, aged 2-25 years. Morphometric data, including midsagittal vocal tract length, shape, and proportions, were collected using computer graphic techniques. There was a significant positive correlation between vocal tract length and body size (either height or weight). The data also reveal clear differences in male and female vocal tract morphology, including changes in overall vocal tract length and the relative proportions of the oral and pharyngeal cavity. These sex differences are not evident in children, but arise at puberty, suggesting that they are part of the vocal remodeling process that occurs during puberty in males. These findings have implications for speech recognition, speech forensics, and the evolution of the human speech production system, and provide a normative standard for future studies of human vocal tract morphology and development.

Growth dynamics of the cricoid cartilage and subglottic injury. An autoradiographic and histometric study in the rabbit.

Earlier studies in young growing rabbits have suggested that post-traumatic developmental deformities of the cricoid might play a role in failing treatment in children with similar injuries. Specific patterns of malformations in the animals occurred preferentially at the anterior side of the cricoid ring. In this study, the growth dynamics of the cricoid were studied by histometry and autoradiography. Results indicated that (1) the cell/matrix ratio remains unchanged from 4 to 24 weeks of age, with both tissue components thus contributing equally to growth of the cricoid; (2) mitoses occur in cartilage and perichondrium, indicating interstitial as well as appositional growth; (3) mitotic activity is mainly restricted to the first 4 weeks of life, while cell hypertrophy is thereafter the dominant feature; (4) the highest degree of mitotic activity and cell hypertrophy is found in the anterior half of the cricoid ring which therefore can be considered as a growth center. This center might play a role in the development of trauma-induced deformation in the anterior part of the cricoid ring.

Whole organ evaluation of collagen in the developing human larynx and adjoining anatomic structures (hyoid and trachea).

The collagen composition (types I, II, and III) of the normal developing human larynx and trachea was examined by biochemical methods. Autopsy specimens of larynges with attached upper tracheal rings were obtained from 28 humans ranging in age from birth to 44 years. The specimens were randomly collected, but excluded if laryngeal disease existed. The age, sex, and cause of death were documented. Collagen is important in the growth, development, repair, regeneration, and structural and functional integrity of the laryngeal framework. A preliminary report of selected cartilaginous components of the larynx was previously published by the authors, which studied the changes in the phenotypic expression of the collagen genes in children from the newborn period to 5 years 10 months of age. The current study included all of the functioning components of the skeletal larynx and trachea. The results of biochemical examination of these tissues are reported, and the potential clinical significance of the results of the study is discussed.

Does early expansion surgery have a role in the management of congenital subglottic stenosis?

To better define the clinical course of congenital subglottic stenosis, the authors reviewed a cohort of 27 children managed with long-term tracheotomy and interval bronchoscopy. Rates of spontaneous resolution were 19% at 6 months, 39% at 12 months, and 69% at 18 months (Kaplan-Meier survival analysis). Children older than 4 months of age at tracheotomy tended to have more rapid resolution of their stenoses (P = .08). Overall, the median time to decannulation was 15.8 months (95% confidence interval, 13.9 to 17.6 months). One death was possibly tracheotomy-related, and 12 (44%) of the children experienced complications or sequelae resulting in new or extended hospitalization. Considering the prolonged cannulation necessary for spontaneous resolution of congenital subglottic stenosis, the role of long-term tracheotomy as the sole form of management may be limited. Once the need for intervention is apparent, the authors recommend early consideration of cricoid split or laryngotracheoplasty as alternatives to long-term tracheotomy.

Cricoid quartersection vs. anterior-posterior cricoid split: effect on subglottic growth in rabbits.

Five-week-old New Zealand white rabbits were divided into three groups: control, anterior-posterior cricoid split with stent, and cricoid quartersection (anterior-posterior-lateral cricoid split) with stent. The stents were removed 2 weeks after placement. The rabbits were allowed to grow for six months, at which time they were killed and the larynges were studied. Average, minimal, and maximal subglottal cross-sectional areas were calculated for each animal and adjusted for weight. The cricoid quartersection group had significantly greater average, minimal, and maximal subglottal cross-sectional areas compared to controls and significantly greater minimal and maximal cross-sectional areas compared to the anterior-posterior cricoid split group. The anterior-posterior cricoid split group and the control group did not significantly differ with respect to any of the three parameters. The results indicate that anterior-posterior cricoid split and cricoid quartersection do not adversely affect subglottic growth. Cricoid quartersectioning was superior to the anterior-posterior cricoid split in its ability to expand subglottic airway dimension.