Analysis of the pharynx and the trachea by the acoustic reflection method in children: A pilot study

Anatomic development of the upper airway during the first five years of life: A three-dimensional imaging study

PURPOSE

Normative data on the growth and development of the upper airway across the sexes is needed for the diagnosis and treatment of congenital and acquired respiratory anomalies and to gain insight on developmental changes in speech acoustics and disorders with craniofacial anomalies.

METHODS

The growth of the upper airway in children ages birth to 5 years, as compared to adults, was quantified using an imaging database with computed tomography studies from typically developing individuals. Methodological criteria for scan inclusion and airway measurements included: head position, histogram-based airway segmentation, anatomic landmark placement, and development of a semi-automatic centerline for data extraction. A comprehensive set of 2D and 3D supra- and sub-glottal measurements from the choanae to tracheal opening were obtained including: naso-oro-laryngo-pharynx subregion volume and length, each subregion's superior and inferior cross-sectional-area, and antero-posterior and transverse/width distances.

RESULTS

Growth of the upper airway during the first 5 years of life was more pronounced in the vertical and transverse/lateral dimensions than in the antero-posterior dimension. By age 5 years, females have larger pharyngeal measurement than males. Prepubertal sex-differences were identified in the subglottal region.

CONCLUSIONS

Our findings demonstrate the importance of studying the growth of the upper airway in 3D. As the lumen length increases, its shape changes, becoming increasingly elliptical during the first 5 years of life. This study also emphasizes the importance of methodological considerations for both image acquisition and data extraction, as well as the use of consistent anatomic structures in defining pharyngeal regions.

Endonasal measurements by acoustic rhinometry in children: A preliminary study

The acoustic reflection method (ARM) is a non-invasive technique which uses the reflection of acoustic waves to measure the cross sectional area of nasal cavities in adults and patency of endotracheal tubes. Characteristics and volume of normal nasal cavities in pre-school children has so far not been studied.

OBJECTIVE

The aim of this study was to determine the optimal ARM recording and the minimal cross-sectional area (MCA) and volume (NV) values in healthy children.

DESIGN

Prospective monocentric study using the ARM in pre-school children (<6 years of age).

RESULTS - DISCUSSION

Seventy children (age 2 to 5) were included in the study. Reliable measures were difficult to obtain in children younger than 2 years of age. The use of a standard nosepiece and a single-use surgical filter enabled reliable, serial recordings. Mean MCA values were 0.46, 0.53 and 0.58 cm² in the 24-35, 36-47 and 48-60 months-old age groups, respectively. Mean NV values were 2.14, 2.59, and 2.86 cm³ in the same age groups. The MCA and NV values were significantly correlated with height, age and weight. In conclusion, the ARM is feasible in children over the age of 2 and seems to be a promising non-invasive tool to study the nasal cavity patency, anatomy, and volume.

The acoustic reflection method for the assessment of paediatric upper airways

The acoustic reflection method (ARM) is based on the analysis of the reflection of an acoustic wave in the airway, allowing the calculation of its longitudinal cross-sectional area profile and airway resistance. The ARM represents a simple, quick and totally non invasive tool for the investigation of the upper airways, requiring minimal cooperation, which makes this technique particularly suitable for children. Normal values of the minimal cross sectional area of the upper airways in children have been recently published. The ARM has shown its utility in the investigation of the nasal cavity in healthy and diseased children and of the upper airways in children with various diseases such as mucopolysaccharidosis and cystic fibrosis. This simple, rapid, and inexpensive technique seems promising for the non-invasive investigation of the whole upper airway during wakefulness in children, both in health and disease, and may constitute a complementary or alternative method to explore and follow children with anomalies of the upper airways.

Pregnancy is associated with a decrease in pharyngeal but not tracheal or laryngeal cross-sectional area: a pilot study using the acoustic reflection method

BACKGROUND

The risk of difficult upper airway access is increased during pregnancy, especially in labor. Changes in upper airway calibre have been poorly studied during pregnancy. The acoustic reflection method is a non-invasive technique that allows a longitudinal assessment of the cross-sectional area of the upper airway from the mouth to carina. We used this technique to evaluate upper airway calibre during normal pregnancy.

METHODS

We conducted a prospective, single centre, observational study with a clinical and upper airway acoustic reflection method evaluation of healthy women during the first, second and third trimesters of pregnancy, and up to two days and one month after delivery.

RESULTS

Fifty women participated to the study. The mean pharyngeal cross-sectional area decreased between the first and third trimesters (P < 0.001) with no significant change of the minimal and mean tracheal cross-sectional areas. The Mallampati score increased during pregnancy between the first and third trimesters (P< 0.001).

CONCLUSION

Using measurements with the acoustic reflection method, normal pregnancy is associated with a significant reduction in the cross-sectional area of the pharynx and a concomitant increase in the Mallampati score. No change was observed in the minimal and mean tracheal cross-sectional areas.