Advancement of the mandible improves velopharyngeal airway patency

1995 ◽  
Vol 79 (6) ◽  
pp. 2132-2138 ◽  
Author(s):  
S. Isono ◽  
A. Tanaka ◽  
Y. Sho ◽  
A. Konno ◽  
T. Nishino
Keyword(s):  
Static Pressure ◽  
Video Recording ◽  
Cross Sectional Area ◽  
Sectional Area ◽  
Cross Sectional ◽  
Airway Patency ◽  
Pharyngeal Airway ◽  
Obstructive Sleep ◽  
Pressure Area ◽  
Nasal Pressure

The velopharynx is the most common site of obstruction in patients with obstructive sleep apnea (OSA). Advancement of the mandible effectively reverses the pharyngeal obstruction. Accordingly, we hypothesized that mandibular advancement increases cross-sectional area of several segments of the upper airway, including the velopharynx and the oropharynx. We examined the pressure-area properties of the pharyngeal airway in 13 patients with OSA. Under general anesthesia and total muscle paralysis, the pharynx was visualized with an endoscope connected to a video-recording system. During an experimentally induced apnea, we manipulated the nasal pressure from 20 cmH2O to the point of total closure at the velopharynx. The procedure was repeated after maximal forward displacement of the mandible. Measurements of the cross-sectional area at different levels of nasal pressure allowed construction of a static pressure-area relationship of the “passive pharynx,” where active neuromuscular factors are suppressed. In 12 of 13 patients with OSA, advancement of the mandible stabilized the airway by reducing the closing pressure and increasing the area at any airway pressure. Thus the maneuver shifted the static pressure-area curve of the velopharynx and the oropharynx upward in these patients. We conclude that anterior movement of the mandible widens the retropalatal airway as well as that at the base of the tongue in the passive pharynx of OSA patients.

Sniffing Position Improves Pharyngeal Airway Patency in Anesthetized Patients with Obstructive Sleep Apnea

2005 ◽  
Vol 103 (3) ◽  
pp. 489-494 ◽  
Author(s):  
Shiroh Isono ◽  
Atsuko Tanaka ◽  
Teruhiko Ishikawa ◽  
Yugo Tagaito ◽  
Takashi Nishino
Keyword(s):  
Obstructive Sleep Apnea ◽  
Sleep Apnea ◽  
Static Pressure ◽  
Cross Sectional ◽  
Airway Patency ◽  
Neck Position ◽  
Pharyngeal Airway ◽  
Obstructive Sleep ◽  
Pressure Area ◽  
Closing Pressure

Background Appropriate bag-and-mask ventilation with patent airway is mandatory during induction of general anesthesia. Although the sniffing neck position is a traditionally recommended head and neck position during this critical period, knowledge of the influences of this position on the pharyngeal airway patency is still inadequate. Methods Total muscle paralysis was induced with general anesthesia in 12 patients with obstructive sleep apnea, eliminating neuromuscular factors contributing to pharyngeal patency. The cross-sectional area of the pharynx was measured endoscopically at different static airway pressures. Comparison of static pressure-area plot between the neutral and sniffing neck positions allowed assessment of the influence of the neck position change on the mechanical properties of the pharynx. Results The static pressure-area curves of the sniffing position were above those of neutral neck position, with increasing maximum cross-sectional area and decreasing the closing pressure at both retropalatal and retroglossal airways. The beneficial effects of the sniffing position were greater in obstructive sleep apnea patients with higher closing pressure and smaller body mass index. Conclusions Sniffing position structurally improves maintenance of the passive pharyngeal airway in patients with obstructive sleep apnea and may be beneficial for both mask ventilation and tracheal intubation during anesthesia induction.

Lateral Position Decreases Collapsibility of the Passive Pharynx in Patients with Obstructive Sleep Apnea

2002 ◽  
Vol 97 (4) ◽  
pp. 780-785 ◽  
Author(s):  
Shiroh Isono ◽  
Atsuko Tanaka ◽  
Takashi Nishino
Keyword(s):  
Obstructive Sleep Apnea ◽  
Sleep Apnea ◽  
Static Pressure ◽  
Lateral Position ◽  
Cross Sectional Area ◽  
The Body ◽  
Sectional Area ◽  
Cross Sectional ◽  
Obstructive Sleep ◽  
Pressure Area

Background Reduction of nocturnal obstructive events during lateral position in patients with obstructive sleep apnea was previously reported. However, little information is available regarding mechanisms of the improvement and the precise pharyngeal site influenced by the lateral position. The authors tested the hypothesis that structural properties of the passive pharynx change by changing the body position from supine to lateral. Method Total muscle paralysis was induced with general anesthesia in eight patients with obstructive sleep apnea, eliminating neuromuscular factors contributing to pharyngeal patency. The cross-sectional area of the pharynx was measured endoscopically at different static airway pressures. Comparison of static pressure-area plot between the positions allowed assessment of the influence of the position change on the mechanical properties of the pharynx. Results The static pressure-area curves of the lateral position were above those of the supine position, with increasing maximum cross-sectional area and decreasing the closing pressure at both retropalatal and retroglossal airways. Conclusions Lateral position structurally improves maintenance of the passive pharyngeal airway in patients with obstructive sleep apnea.

COMPUTATIONAL FLUID DYNAMICS MODELING OF PHARYNGEAL AIRWAY RESISTANCE BASED ON CONE-BEAM COMPUTED TOMOGRAPHY

2019 ◽  
Vol 19 (06) ◽  
pp. 1950045
Author(s):  
THYAGASEELY SHEELA PREMARAJ ◽  
SIYEONG JU ◽  
SUNDARALINGAM PREMARAJ ◽  
SUNG K. KIM ◽  
LINXIA GU
Keyword(s):  
Fluid Dynamic ◽  
Cross Sectional Area ◽  
Post Treatment ◽  
Cone Beam ◽  
Sectional Area ◽  
Cross Sectional ◽  
Airway Patency ◽  
Pharyngeal Airway ◽  
Splint Therapy ◽  
Percentage Area

Background: Oral appliances for treating patients with sleep related disorders such as snoring and disturbed sleep could alter the morphology of the pharyngeal airway and thus its flow dynamics as well as airway patency. Splint therapy, i.e., positioning the mandibular condyles in centric relation (CR) with maxillary anterior guided orthotics (MAGO), with regard to pharyngeal airway patency, is causing increased attention. The goal of this work is to quantitatively examine the fluid dynamic changes within the pharyngeal airway when the mandible is positioned in CR and its association with airway patency. Materials and Methods: Patient-specific computational fluid dynamics models were reconstructed from pre- and post- treatment high-resolution cone-beam computed tomography images for two patients who had undergone MAGO therapy. The minimal cross-sectional area and total volume of the pharyngeal airway were measured in the pre- and post-treatment for a total of four models. These two subjects were chosen out of 18 patients based on the airway volume changes in pre- and post-treatment. Subject 1 had a dramatic increase in the airway volume, whereas subject 2 kept a similar airway volume following the therapy. Both subjects anecdotally reported improvement in snoring, breathing and overall sleep quality. Results: We examined three parameters, i.e., the classically defined resistance of airway in terms of pressure drop, the minimal cross-sectional area, and the pharyngeal airway volume. We also proposed a new fluid dynamic parameter: the percentage area of higher vorticity, to be correlated with the clinical efficacy of the appliance for airway patency. All four parameters could be used as index factors for subject 1 to explain the measurable clinical outcomes and the subjective report regarding quality of breathing, snoring cessation, and improvement in sleep of the patient. But only the minimal cross-sectional area and percentage area of higher vorticity could explain the clinical observations and subjective outcome in subject 2 who reported similar effects after the treatment. Conclusion: Splint therapy expanded the minimal cross-sectional area in both subjects, but did not necessarily influence the pharyngeal airway volume. The airway shape changed in terms of the percentage area of higher vorticity and the minimal cross-sectional area. Further studies are needed to assess the clinical efficacy of MAGO in reducing or eliminating the sleep-related breathing difficulties and snoring.

scholarly journals Sitting Posture Decreases Collapsibility of the Passive Pharynx in Anesthetized Paralyzed Patients with Obstructive Sleep Apnea

2010 ◽  
Vol 113 (4) ◽  
pp. 812-818 ◽  
Author(s):  
Yugo Tagaito ◽  
Shiroh Isono ◽  
Atsuko Tanaka ◽  
Teruhiko Ishikawa ◽  
Takashi Nishino
Keyword(s):  
Obstructive Sleep Apnea ◽  
Sleep Apnea ◽  
Cross Sectional Area ◽  
Anesthesia Induction ◽  
Sectional Area ◽  
Postural Change ◽  
Cross Sectional ◽  
Pharyngeal Airway ◽  
Supine Posture ◽  
Obstructive Sleep

Background Obstructive sleep apnea (OSA) is an independent risk factor for difficult and/or impossible mask ventilation during anesthesia induction. Postural change from supine to sitting improves nocturnal breathing in patients with OSA. The purpose of this study was to evaluate the effect of patient position on collapsibility of the pharyngeal airway in anesthetized and paralyzed patients with OSA. The authors tested the hypothesis that the passive pharynx is structurally less collapsible during sitting than during supine posture. Method Total muscle paralysis was induced with general anesthesia in nine patients with OSA, eliminating neuromuscular factors contributing to pharyngeal patency. The cross-sectional area of the pharynx was measured endoscopically at different static airway pressures. Comparison of static pressure-area plots between the supine and sitting (62° head-up) allowed assessment of the postural differences of the mechanical properties of the pharynx. Results : Maximum cross-sectional area was greater during sitting than during supine posture at both retropalatal (median (10th-90th percentile): 1.91 (1.52-3.40) versus 1.25 (0.65-1.97) cm) and retroglossal (2.42 (1.72-3.84) versus 1.75 (0.47-2.35) cm) airways. Closing pressure of the passive pharynx was significantly lower during sitting than supine posture. Differences of the closing pressures between the postures are 5.89 (3.73-11.6) and 6.74 (4.16-9.87) cm H2O, at retropalatal and retroglossal airways, respectively, and did not differ between the pharyngeal segments. Conclusions Postural change from supine to sitting significantly improves collapsibility of pharyngeal airway in anesthetized and paralyzed patients with OSA.

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.

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.

Left ventricular wave speed

2001 ◽  
Vol 91 (6) ◽  
pp. 2531-2536 ◽  
Author(s):  
Jiun-Jr Wang ◽  
Kim H. Parker ◽  
John V. Tyberg
Keyword(s):  
Wave Speed ◽  
Pulse Generator ◽  
Diastolic Pressure ◽  
Left Ventricular ◽  
Cross Sectional Area ◽  
Sectional Area ◽  
Cross Sectional ◽  
Pressure Transducers ◽  
Pressure Area ◽  
Axis Length

Left ventricular (LV) wave speed (LVWS) was studied experimentally and confirmed in theory. Combining the definition of elastance (E) with the equations for the conservation of mass and momentum shows that LVWS is proportional to the square root of E LA, where L is long-axis length and A is the cross-sectional area, and the density of the blood. (We defined E LA = γ, where γ is compressibility.) We studied nine open chest, anesthetized dogs, three of which were studied during caval constriction when LV end-diastolic pressure was ≤0 mmHg. The hearts were paced at ∼90 beats/min, and LV cross-sectional area was measured by using two pairs of ultrasonic crystals; E was calculated from the LV pressure-area loop. A pulse generator was connected to the LV apex, and LVWS was measured by using two pressure transducers: one near the apex and the other near the base. Their distance was measured roentgenographically and compared with the diameter of a reference ball. LVWS ranged from ∼1 m/s during diastole to ∼10 m/s during systole. The slope of the log c(where c is wave speed) vs. log γ was 0.546, which is in agreement with theory (0.5). When γ ≤ 0, LVWS was ∼1.5 m/s.

The Use of a Laser Micrometer System to Determine the Cross-Sectional Shape and Area of Ligaments: A Comparative Study With Two Existing Methods

1990 ◽  
Vol 112 (4) ◽  
pp. 426-431 ◽  
Author(s):  
Savio L.-Y. Woo ◽  
Michael I. Danto ◽  
Karen J. Ohland ◽  
Thay Q. Lee ◽  
Peter O. Newton
Keyword(s):  
Constant Pressure ◽  
Cruciate Ligament ◽  
Applied Pressure ◽  
Cross Sectional Area ◽  
Sectional Area ◽  
Cross Sectional ◽  
Proximal Site ◽  
Pressure Area ◽  
The Cross ◽  
Sectional Shape

Determination of the tensile stresses in ligaments and tendons during uniaxial loading depends on accurate measurement of the cross-sectional area. In this study, a laser micrometer system was employed to evaluate the cross-sectional shape and area of the medial collateral ligament (MCL) at three locations and anterior cruciate ligament (ACL). In a New Zealand White (NZW) rabbit, morphologic sections of the ligaments were made to verify the cross-sectional shape reconstructed by the laser micrometer system. The areas obtained by the laser micrometer system from ten additional NZW rabbits were compared with those obtained by two other methods commonly used to measure the cross-sectional area of ligaments and tendons: one method uses digital calipers and the other a constant pressure (0.12 MPa) area micrometer. For the MCL, the digital calipers yielded results very similar to those of the laser micrometer, but the constant pressure area micrometer yielded values 20 percent lower. The area measured at the proximal site of the MCL was 13 percent greater than the area measured at the joint line and distal line. For the ACL, the values obtained by the digital calipers and constant pressure area micrometer were 16 and 20 percent lower, respectively. Because of the irregular shape exhibited by the rabbit ACL, the digital calipers could not accurately measure the crosssectional area. The constant pressure area micrometer yielded lower values for the cross-sectional area of both the MCL and ACL, presumably due to the applied pressure which caused changes in both the cross-sectional shape and area.

Retropalatal Cross-Sectional Area Is Predictive of Obstructive Sleep Apnea in Patients With Syndromic Craniosynostosis

2019 ◽  
Vol 57 (5) ◽  
pp. 560-565 ◽  
Author(s):  
Cory M. Resnick ◽  
Jason K. Middleton ◽  
Carly E. Calabrese ◽  
Karan Ganjawalla ◽  
Bonnie L. Padwa
Keyword(s):  
Obstructive Sleep Apnea ◽  
Sleep Apnea ◽  
Upper Airway ◽  
Cross Sectional Area ◽  
Secondary Outcome ◽  
Outcome Variable ◽  
Sectional Area ◽  
Cross Sectional ◽  
Syndromic Craniosynostosis ◽  
Obstructive Sleep

Objective: There is a high rate of obstructive sleep apnea (OSA) in patients with syndromic craniosynostosis (SCS). Little is known about the airway anatomy in this population. The purpose of this study is to characterize the 3 dimensional (3D) upper airway in patients with SCS with and without OSA. Design: This is a retrospective study of patients with SCS treated at Boston Children’s Hospital from 2000 to 2015. Patients were divided into OSA and no-OSA groups based on polysomnography. Predictor variables included age, sex, body mass index (BMI), and 3D upper airway measurements. The primary outcome variable was the presence or absence of OSA. Secondary outcome variables were apnea–hypopnea index and oxygen saturation nadir. Descriptive and bivariate statistics were computed, and significance was set as P < .05. Results: There were 24 patients: 16 in the OSA group and 8 in the no-OSA group. The 2 groups did not differ significantly by age, BMI, or syndromic diagnosis. The presence of OSA was associated with a smaller minimum retropalatal cross-sectional area (minRPCSA; P < .001). In a logistic regression model controlling for age, sex, and upper airway length, minRPCSA was the primary predictor of OSA ( P ≤ .002). Receiver operating characteristic analysis determined minRPCSA = 55.3 mm2 to be the optimal diagnostic threshold for OSA, with sensitivity = 100% and specificity = 87.5% ( P < .001). Conclusion: A minRPCSA ≤55.3 mm2 is predictive of the presence of OSA in patients with SCS.

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