Effect of position and lung volume on upper airway geometry

1987 ◽  
Vol 63 (1) ◽  
pp. 375-380 ◽  
Author(s):  
J. M. Fouke ◽  
K. P. Strohl
Keyword(s):  
Lung Volume ◽  
Supine Position ◽  
Upper Airway ◽  
Upright Position ◽  
Cross Sectional Area ◽  
Sectional Area ◽  
Position Change ◽  
Cross Sectional ◽  
Acoustic Reflection ◽  
Residual Capacity

The occurrence of upper airway obstruction during sleep and with anesthesia suggests the possibility that upper airway size might be compromised by the gravitational effects of the supine position. We used an acoustic reflection technique to image airway geometry and made 180 estimates of effective cross-sectional area as a function of distance along the airway in 10 healthy volunteers while they were supine and also while they were seated upright. We calculated z-scores along the airway and found that pharyngeal cross-sectional area was smaller in the supine than in the upright position in 9 of the 10 subjects. For all subjects, pharyngeal cross-sectional area was 23 +/- 8% smaller in the supine than in the upright position (P less than or equal to 0.05), whereas glottic and tracheal areas were not significantly altered. Because changing from the upright to the supine position causes a decrease in functional residual capacity (FRC), six of these subjects were placed in an Emerson cuirass, which was evacuated producing a positive transrespiratory pressure so as to restore end-expiratory lung volume to that seen before the position change. In the supine posture an increase in end-expiratory lung volume did not change the cross-sectional area at any point along the airway. We conclude that pharyngeal cross-sectional area decreases as a result of a change from the upright to the supine position and that the mechanism of this change is independent of the change in FRC.

Pharyngeal cross-sectional area in normal men and women

1986 ◽  
Vol 61 (3) ◽  
pp. 890-895 ◽  
Author(s):  
I. G. Brown ◽  
N. Zamel ◽  
V. Hoffstein
Keyword(s):  
Measurement Techniques ◽  
Upper Airway ◽  
Cross Sectional Area ◽  
Sectional Area ◽  
Cross Sectional ◽  
Lung Volumes ◽  
Acoustic Reflection ◽  
Obstructive Sleep ◽  
Males And Females ◽  
Pharyngeal Area

Pharyngeal size and the dynamic behavior of the upper airway may be important factors in modulating respiratory airflow. Patients with obstructive sleep apnea are known to have reduced pharyngeal cross-sectional area. However, no systematic measurements of pharyngeal area in healthy asymptomatic subjects are available, in part due to the lack of simple, rapid, and noninvasive measurement techniques. We utilized the acoustic reflection technique to measure pharyngeal cross-sectional area in 24 healthy volunteers (14 males, 10 females). Pharyngeal area was measured during a continuous slow expiration from total lung capacity (TLC) to residual volume (RV). We compared pharyngeal cross-sectional areas in males and females at three lung volumes: TLC, 50% of vital capacity (VC), and RV. In males, pharyngeal areas (means +/- SD) were 6.4 +/- 1.3 cm2 at TLC, 5.4 +/- 0.9 cm2 at 50% VC, and 4.1 +/- 0.8 cm2 at RV. In females, pharyngeal areas were 4.8 +/- 0.6 cm2 at TLC, 4.2 +/- 0.5 cm2 at 50% VC, and 3.7 +/- 0.6 cm2 at RV. The difference in area between males and females was statistically significant at TLC and 50% VC but not at RV. However, when the pharyngeal cross-sectional area was normalized for body surface area, this difference was not significant. In males there was a negative correlation of pharyngeal area with age. We conclude that sex differences in pharyngeal area are related to body size, pharyngeal area shows a similar variation with lung volumes in males and females, and in males pharyngeal area reduces with age.

A three-microphone acoustic reflection technique using transmitted acoustic waves in the airway

2013 ◽  
Vol 115 (8) ◽  
pp. 1119-1125 ◽  
Author(s):  
Yuki Fujimoto ◽  
Jyongsu Huang ◽  
Toshiharu Fukunaga ◽  
Ryo Kato ◽  
Mari Higashino ◽  
...  
Keyword(s):  
Acoustic Waves ◽  
Cross Sectional Area ◽  
Distance Functions ◽  
Sectional Area ◽  
Wave Tube ◽  
Cross Sectional ◽  
Reflected Waves ◽  
Acoustic Reflection ◽  
Obstructive Sleep ◽  
And Function

The acoustic reflection technique noninvasively measures airway cross-sectional area vs. distance functions and uses a wave tube with a constant cross-sectional area to separate incidental and reflected waves introduced into the mouth or nostril. The accuracy of estimated cross-sectional areas gets worse in the deeper distances due to the nature of marching algorithms, i.e., errors of the estimated areas in the closer distances accumulate to those in the further distances. Here we present a new technique of acoustic reflection from measuring transmitted acoustic waves in the airway with three microphones and without employing a wave tube. Using miniaturized microphones mounted on a catheter, we estimated reflection coefficients among the microphones and separated incidental and reflected waves. A model study showed that the estimated cross-sectional area vs. distance function was coincident with the conventional two-microphone method, and it did not change with altered cross-sectional areas at the microphone position, although the estimated cross-sectional areas are relative values to that at the microphone position. The pharyngeal cross-sectional areas including retropalatal and retroglossal regions and the closing site during sleep was visualized in patients with obstructive sleep apnea. The method can be applicable to larger or smaller bronchi to evaluate the airspace and function in these localized airways.

A Simple Endoscopic Technique for Measuring the Cross-Sectional Area of the Upper Airway in a Rabbit Model

2018 ◽  
Vol 127 (4) ◽  
pp. 275-281 ◽  
Author(s):  
Paul R. Wistermayer ◽  
Wesley R. McIlwain ◽  
Nicholas Ieronimakis ◽  
Derek J. Rogers
Keyword(s):  
Rabbit Model ◽  
Upper Airway ◽  
Cross Sectional Area ◽  
Endoscopic Technique ◽  
Sectional Area ◽  
Cross Sectional ◽  
The Cross

Upper Airway 3D Changes of Patients With Cleft Lip and Palate After Orthognathic Surgery

2018 ◽  
Vol 56 (3) ◽  
pp. 314-320 ◽  
Author(s):  
Marilia Sayako Yatabe-Ioshida ◽  
Letícia Dominguez Campos ◽  
Renato Yassukata Yaedu ◽  
Ivy Kiemle Trindade-Suedam
Keyword(s):  
Orthognathic Surgery ◽  
Cleft Lip ◽  
Cleft Lip And Palate ◽  
Upper Airway ◽  
Cross Sectional Area ◽  
Sectional Area ◽  
Class Iii ◽  
Linear Measurements ◽  
Cross Sectional ◽  
Skeletal Class

Objectives: The purpose of this study was to 3-dimensionally assess the airway characteristics of patients with unilateral cleft lip and palate (UCLP) and bilateral cleft lip and palate (BCLP) who underwent orthognathic surgery. Design: This was a retrospective study. Setting: The study took place at a national referral center for cleft lip and palate rehabilitation. Patients and Participants: The sample comprised cone-beam computed tomography (CBCT) scans obtained before and after orthognathic surgery of 15 individuals (30 CBCT scans), divided into 2 groups: UCLP group (n = 9 patients/18 CBCT scans) and BCLP group (n = 6/12 CBCT scans). All patients had a nonsyndromic UCLP or BCLP and a skeletal class III malocclusion at the preoperative period. Interventions: Airway volume, pharyngeal minimal cross-sectional area (mCSA), location of mCSA, sella-nasion-A point (SNA) and sella-nasion-B point (SNB) angles, and condylion-A point and condyloid-gnathion linear measurements were assessed in open-source software (ITK-SNAP and SlicerCMF). Main Outcome Measure: Airway dimensions of patients with UCLP and BCLP increase after orthognathic surgery. Results: After orthognathic surgery, UCLP group showed a significant 20% increase in nasopharynx volume. Although not significant, BCLP group also showed an increase of 18% in the same region. Minimal cross-sectional area remained dimensionally stable after surgery and was all located in the oropharynx region, on both groups. Additionally, a positive correlation was observed between volume and mCSA on both groups. Conclusion: Overall, individuals with UCLP and BCLP showed an increase in the upper airway after orthognathic surgery and this might explain the breathing and sleep improvements reported by the patients after the surgery.

Upper Airway Effective Compliance during Wakefulness and Sleep in Obese Adolescents Studied via 2-Dimensional Dynamic MRI and Semi-automated Image Segmentation

2021 ◽  
Author(s):  
Kok Ren Choy ◽  
Sanghun Sin ◽  
Yubing Tong ◽  
Jayaram K. Udupa ◽  
Dirk M. Luchtenburg ◽  
...  
Keyword(s):  
Upper Airway ◽  
Dynamic Mri ◽  
Cross Sectional Area ◽  
Apnea Hypopnea Index ◽  
Morphological Operations ◽  
Sectional Area ◽  
Cross Sectional ◽  
Automated Method ◽  
Obstructive Sleep ◽  
Effective Compliance

Novel biomarkers of upper airway biomechanics may improve diagnosis of Obstructive Sleep Apnea Syndrome (OSAS). Upper airway effective compliance (EC), the slope of cross-sectional area versus pressure estimated using computational fluid dynamics (CFD), correlates with apnea-hypopnea index (AHI) and critical closing pressure (Pcrit). The study objectives are to develop a fast, simplified method for estimating EC using dynamic MRI and physiological measurements, and to explore the hypothesis that OSAS severity correlates with mechanical compliance during wakefulness and sleep. Five obese children with OSAS and five obese control subjects age 12-17 underwent anterior rhinomanometry, polysomnography and dynamic MRI with synchronized airflow measurement during wakefulness and sleep. Airway cross-section in retropalatal and retroglossal section images was segmented using a novel semi-automated method that uses optimized singular-value decomposition (SVD) image filtering and k-means clustering combined with morphological operations. Pressure was estimated using rhinomanometry Rohrer coefficients and flow rate, and EC calculated from the area-pressure slope during five normal breaths. Correlations between apnea-hypopnea index (AHI), EC, and cross-sectional area (CSA) change were calculated using Spearman rank correlation. The semi-automated method efficiently segmented the airway with average Dice Coefficient above 89% compared to expert manual segmentation. AHI correlated positively with EC at the retroglossal site during sleep (rs=0.74, p=0.014), and with change of EC from wake to sleep at the retroglossal site (rs=0.77, p=0.01). CSA change alone did not correlate significantly with AHI. EC, a mechanical biomarker which includes both CSA change and pressure variation, is a potential diagnostic biomarker for studying and managing OSAS.

Relationship between lung volume and tracheal area as assessed by acoustic reflection

1988 ◽  
Vol 64 (3) ◽  
pp. 1050-1054 ◽  
Author(s):  
L. J. Brooks ◽  
P. J. Byard ◽  
R. C. Helms ◽  
J. M. Fouke ◽  
K. P. Strohl
Keyword(s):  
Young Adults ◽  
Body Size ◽  
Lung Disease ◽  
Lung Volume ◽  
Vital Capacity ◽  
Significant Positive Correlation ◽  
Lung Parenchyma ◽  
Sectional Area ◽  
Cross Sectional ◽  
Acoustic Reflection

To determine whether airway size correlates with measures of lung or body size, we used the acoustic reflection technique to calculate tracheal cross-sectional area in 103 healthy young adults. Men have significantly larger tracheas than women [2.48 ± 0.08 vs. 1.91 ± 0.05 (SE) cm2, P less than 0.001]. Within each sex, there is no correlation between tracheal size and body size or maximal expiratory flows. There is a significant positive correlation between tracheal area and vital capacity in males only (r = 0.36, P less than 0.01). These results support the concept of dysanapsis, relatively independent growth of the airways and lung parenchyma, as well as sex-related differences in airway size and growth. Inherent airway size may be a factor in the development and/or progression of lung disease.

Determinants of forced expiratory flows in newborn infants

1982 ◽  
Vol 53 (5) ◽  
pp. 1220-1227 ◽  
Author(s):  
L. M. Taussig ◽  
L. I. Landau ◽  
S. Godfrey ◽  
I. Arad
Keyword(s):  
Newborn Infants ◽  
Cross Sectional Area ◽  
Physiological Data ◽  
Sectional Area ◽  
Older Children ◽  
Cross Sectional ◽  
Thoracic Gas Volume ◽  
Residual Capacity ◽  
The Cross ◽  
Gas Volume

Maximal flows at functional residual capacity (VmaxFRC) from partial expiratory flow-volume (PEFV) curves (achieved with rapid compression of the chest) were obtained on 11 healthy newborn babies. Mean VmaxFRC, size corrected by dividing absolute values by measured thoracic gas volume, was 1.90 TGV's/s. Specific upstream conductances were high, and the cross-sectional area of the flow-limiting segment was estimated to be approximately 0.30 cm2 in the three infants on whom recoil pressures at FRC were also measured. The cross-sectional area of the major bronchi in the neonate is approximately 0.26–0.30 cm2. PEFV curves were convex to the volume axis. Many of the neonates increased their flows while breathing a helium-oxygen gas mixture. These results suggest 1) size-corrected flows are higher in the neonate than in older children or adults; 2) the site of the flow-limiting segment at FRC during maximal expiratory maneuvers is in large proximal airways, similar to the adult; and 3) the relationship of airway size to parenchymal size may be similar in neonates and adults or, in fact, airways may be larger, relative to parenchyma, in neonates. These physiological data do not support the hypothesis, based on pathological studies, that peripheral airways are disproportionately smaller (when compared with central airways) in infants than in adults.

Gender differences in upper airway compliance during NREM sleep: role of neck circumference

2002 ◽  
Vol 92 (6) ◽  
pp. 2535-2541 ◽  
Author(s):  
James A. Rowley ◽  
Carrie S. Sanders ◽  
Brian R. Zahn ◽  
M. Safwan Badr
Keyword(s):  
Gender Differences ◽  
Gender Difference ◽  
Upper Airway ◽  
Nrem Sleep ◽  
Neck Circumference ◽  
Cross Sectional Area ◽  
Sectional Area ◽  
Cross Sectional ◽  
Significant Difference ◽  
Upper Airway Structure

It has been proposed that the gender difference in sleep apnea prevalence is related to gender differences in upper airway structure and function. We hypothesized that men would have smaller retropalatal cross-sectional area and higher compliance during sleep compared with women. Using upper airway imaging, we measured upper airway cross-sectional area and retropalatal compliance in wakefulness and non-rapid eye movement (NREM) sleep in 15 men and 15 women without sleep-disordered breathing. Cross-sectional area at the beginning of inspiration tended to be larger in men compared with women in both wakefulness [194.5 ± 21.3 vs. 138.8 ± 12.0 (SE) mm2] and NREM sleep (111.1 ± 17.6 vs. 83.3 ± 11.9 mm2; P = 0.058). There was no significant difference, however, after correction for body surface area. Retropalatal compliance also tended to be higher in men during both wakefulness (5.9 ± 1.4 vs. 3.1 ± 1.4 mm2/cmH2O; P = 0.006) and NREM sleep (12.6 ± 2.7 vs. 4.7 ± 2.6 mm2/cmH2O; P = 0.055). However, compliance was similar in men relative to women after correction for neck circumference. We conclude that the gender difference in retropalatal compliance is more accurately attributed to differences in neck circumference between the genders.

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