scholarly journals Bench Assessment of the Effect of a Collapsible Tube on the Efficiency of a Mechanical Insufflation-Exsufflation Device

2019 ◽  
Vol 64 (7) ◽  
pp. 752-759 ◽  
Author(s):  
Romain Lachal ◽  
Bruno Louis ◽  
Fabien Subtil ◽  
Claude Guérin
Keyword(s):  
Collapsible Tube

scholarly journals Feedback modulation of surrounding pressure determines the onset of negative effort dependence in a collapsible tube bench model of the pharyngeal airway

2017 ◽  
Vol 123 (5) ◽  
pp. 1118-1125 ◽  
Author(s):  
Christopher Lambeth ◽  
Benjamin Kolevski ◽  
Terence Amis ◽  
Kristina Kairaitis
Keyword(s):  
Longitudinal Strain ◽  
Initial Conditions ◽  
Driving Pressure ◽  
Chamber Pressure ◽  
Collapsible Tube ◽  
Moderate Amount ◽  
Tissue Pressure ◽  
Pharyngeal Airway ◽  
Obstructive Sleep ◽  
Bench Model

Negative effort dependence (NED), decreased airflow despite increased driving pressure, has been proposed as a specific obstructive sleep apnea (OSA) phenotypic characteristic. We examined conditions under which NED occurs in a collapsible tube, pharyngeal airway bench model with the chamber enclosed, focusing on relationships with surrounding pressure levels and longitudinal strain. Using a vacuum source, graded airflows (V̇; 0–5 l/s) were generated through a thin-walled latex tube enclosed within a rigid, cylindrical chamber, sealed with initial chamber pressures (Pci) of 0–5 cmH2O (separate runs), or opened to the atmosphere. Upstream minus downstream pressure (Pu − Pd), maximum airflow (V̇max), and chamber pressure (Pc) were measured at 0–50% longitudinal strain. NED occurred across the range of Pci and strains studied but was most pronounced for the chamber open condition. With a sealed chamber, V̇ increased and Pc decreased with increasing Pu − Pd until the onset of NED at V̇max and a Pc value that was designated as critical (Pcc). Pcc was lowest (−17 cmH20) and V̇max was highest (~5 l/s) with chamber sealed: Pci = 0 cmH2O and 12.5 to 25% strain. We conclude that for our collapsible tube model, the achievable V̇max before the onset of NED depends on both the initial conditions (Pci and strain) and the dynamics of feedback between driving pressure and chamber pressure (chamber sealed vs. open). NED-based phenotypic analyses for OSA may need to focus on potential feedback control mechanisms (eg lung volume change, muscle activity) that may link peripharyngeal tissue pressure levels to driving pressures for airflow. NEW & NOTEWORTHY A collapsible tube, pharyngeal airway bench model was used to study the role of surrounding pressure and longitudinal wall strain at the onset of negative effort dependence (NED). NED occurred to varying degrees across all conditions tested, but maximum airflow was achieved with 1) low initial surrounding pressure, 2) a feedback mechanism between surrounding pressure and driving pressure; and 3) a moderate amount of strain applied. Potential impacts on OSA phenotypic analyses are discussed.

Oscillations in a Collapsed-Tube Analog of the Brachial Artery Under a Sphygmomanometer Cuff

1989 ◽  
Vol 111 (3) ◽  
pp. 185-191 ◽  
Author(s):  
C. D. Bertram ◽  
C. J. Raymond ◽  
K. S. A. Butcher
Keyword(s):  
High Frequency ◽  
Flow Characteristics ◽  
Low Frequency ◽  
Collapsible Tube ◽  
Tube Size ◽  
Low Frequency Oscillations ◽  
Central Segment ◽  
Experimental Parameters ◽  
Aqueous Flow ◽  
Low Frequency Mode

To determine whether self-excited oscillations in a Starling resistor are relevant to physiological situations, a collapsible tube conveying an aqueous flow was externally pressurized along only a central segment of its unsupported length. This was achieved by passing the tube through a shorter and wider collapsible sleeve which was mounted in Starling resistor fashion in a pressure chamber. The tube size and material, and all other experimental parameters, were as used in our previous Starling resistor studies. Both low- and high-frequency self-excited oscillations were observed, but the low-frequency oscillations were sensitive to the sleeve type and length relative to unsupported distance. Pressure-flow characteristics showed multiple oscillatory modes, which differed quantitatively from those observed in comparable Starling resistors. Slow variation of driving pressure gave differing behavior according to whether the pressure was rising or falling, in accord with the hysteresis noted on the characteristics and in the tube law. The results are discussed in terms of the various possible mechanisms of collapsible tube instability, and reasons are presented for the absence of the low-frequency mode under most physiological circumstances.

Flow limitation in a collapsible tube.

1972 ◽  
Vol 33 (1) ◽  
pp. 150-153 ◽  
Author(s):  
R K Lambert ◽  
T A Wilson
Keyword(s):  
Flow Limitation ◽  
Collapsible Tube

scholarly journals Effect of Initial Axial Strain of Collapsible Tube on Self-Excited Oscillation.

1999 ◽  
Vol 65 (638) ◽  
pp. 3352-3358 ◽  
Author(s):  
Yupeng XIA ◽  
Toshiyuki HAYASE ◽  
Satoru HAYASHI ◽  
Tsuyoshi HAMAYA
Keyword(s):  
Axial Strain ◽  
Collapsible Tube ◽  
Excited Oscillation

Fully Coupled Fluid-Structure Interaction Model of Active Eustachian Tube Function

2008 ◽  
Author(s):  
Francis J. Sheer ◽  
Samir N. Ghadiali
Keyword(s):  
Eustachian Tube ◽  
Ambient Pressure ◽  
Interaction Model ◽  
Surrounding Tissue ◽  
Eustachian Tube Function ◽  
Collapsible Tube ◽  
Structure Interaction ◽  
Novel Treatments ◽  
Tube Function ◽  
Fully Coupled

The Eustachian Tube (ET) is a collapsible tube that connects the Middle Ear (ME) to the nasopharynx (NP). The ET is responsible for three primary functions: 1) regulation of ME pressure 2) protection of the ME from foreign pathogens and 3) drainage of fluid from the ME. [1] In healthy patients, the ET opens during swallowing because the surrounding tissue is deformed by muscle activity. If the ET fails to open, the ME develops painful sub-ambient pressure and fluid accumulates in the ME. ET dysfunction results in Otitis Media (OM), the most common ME disorder in children. The overall goal of our lab is to identify the mechanisms responsible for ET dysfunction and to develop novel treatments for OM that target the ET.

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