Respiratory cross-sectional area-flux measurements of the human chest wall

A new device that utilizes the voltages induced in separate coils encircling the rib cage and abdomen by a magnetic field is described for measurement of cross-sectional areas of the human chest wall (rib cage and abdomen) and their variation during breathing. A uniform magnetic field (1.4 X 10(-7) Tesla at 100 kHz) is produced by generating an alternating current at 100 kHz in two square coils, 1.98 m on each side, parallel to the planes of the areas to be measured and placed symmetrically cephalad and caudad to these planes at a mean distance of 0.53 m. We demonstrated that the accuracy of the device on well-defined surfaces (squares, circles, rectangles, ellipses) was within 1% in all cases. Observed errors are due primarily to small inhomogeneities of the magnetic field and variation of the orientation of the coil relative to the field. Using a second magnetic field (80 kHz) perpendicular to the first, we measured the errors due to nonparallel orientation during quiet breathing and inspiratory capacity maneuvers. In 10 normal subjects, orientation effects were less than 2% for the rib cage and less than 0.7% for the abdomen. In five of these subjects, orientation effects at functional residual capacity in lateral and seated postures were generally less than or equal to 5%, but estimated tidal volume during spontaneous breathing was comparable to measurements in the supine posture. In five curarized patients, we assessed the linearity of volume-motion relationships of the rib cage and abdomen, comparing cross-sectional area and circumference measurements. Departures from linearity using cross-sectional areas were only one-third of those using circumferences. In seven normal subjects we compared cross-sectional area measurements with respiratory inductive plethysmography (RIP) and found comparable estimates of lung volume change over a wide range of relative rib cage contributions to tidal volume (-5 to 105%), with slightly higher standard deviations for the RIP (SD = 10% for RIP; SD = 4% for cross-sectional area).

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Dynamic imaging of the upper airway during respiration in normal subjects

Journal of Applied Physiology ◽

10.1152/jappl.1993.74.4.1504 ◽

1993 ◽

Vol 74 (4) ◽

pp. 1504-1514 ◽

Cited By ~ 91

Author(s):

R. J. Schwab ◽

W. B. Gefter ◽

A. I. Pack ◽

E. A. Hoffman

Keyword(s):

Computed Tomography ◽

Tidal Volume ◽

Upper Airway ◽

Normal Subjects ◽

Dynamic Imaging ◽

Cross Sectional Area ◽

Intraluminal Pressure ◽

Sectional Area ◽

Cross Sectional ◽

Airway Caliber

The present study was conducted to determine the effects of quiet respiration on upper airway caliber in 15 normal subjects by using cine computed tomography. The cine computed tomography (Imatron) scanner was programmed to obtain 8-mm-thick axial slices every 0.4 s during inspiration and expiration at four anatomic levels, from the nasopharynx to the retroglossal region. Airflow (pneumotachograph) was measured, and tidal volume was obtained by integration. Upper airway area, determined by an objective edge detection algorithm, was plotted as a function of tidal volume to generate a loop describing upper airway area changes at each level during a respiratory cycle. The results demonstrate a 17% change in airway size across all anatomic levels during respiration. The maximum upper airway cross-sectional area at all four anatomic levels was significantly greater during expiration than during inspiration. Other major findings include 1) upper airway cross-sectional area decreases slightly during early inspiration, enlarges toward end inspiration, and is larger at end inspiration than at the beginning of inspiration; 2) upper airway cross-sectional area enlarges from end inspiration to the first point in expiration; the airway enlarges further, reaching its maximum early in expiration, and then narrows toward end expiration; and 3) the changes in upper airway dimensions during resting tidal breathing are greater in the lateral than in the anteroposterior direction. The data suggest that during inspiration, the action of negative intraluminal pressure may be largely balanced by the action of the upper airway dilator muscles, whereas during expiration, positive intraluminal pressure produces expansion of the upper airway.

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Mechanical coupling of upper and lower canine rib cages and its functional significance

Journal of Applied Physiology ◽

10.1152/jappl.1988.64.2.620 ◽

1988 ◽

Vol 64 (2) ◽

pp. 620-626 ◽

Cited By ~ 15

Author(s):

T. X. Jiang ◽

M. Demedts ◽

M. Decramer

Keyword(s):

Nerve Stimulation ◽

Phrenic Nerve ◽

Cross Sectional Area ◽

Abdominal Pressure ◽

Sectional Area ◽

Phrenic Nerve Stimulation ◽

Cross Sectional ◽

Rib Cage ◽

Lower Canine ◽

The Relationship

We studied rib cage distortability and reexamined the mechanical action of the diaphragm and the rib cage muscles in six supine anesthetized dogs by measuring changes in upper rib cage cross-sectional area (Aurc) and changes in lower rib cage cross-sectional area (Alrc) and the respective pressures acting on them. During quiet breathing in the intact animal the rib cage behaved as a unit (Aurc: 14.6 +/- 7.9 vs. Alrc: 15.1 +/- 9.6%), whereas considerable distortions of the rib cage occurred during breathing after bilateral phrenicotomy (Aurc: 21.0 +/- 5.1 vs. Alrc: 7.0 +/- 4.8%). These distortions were even more pronounced during phrenic nerve stimulation and separate stimulation of the costal and crural parts of the diaphragm (e.g., phrenic nerve stimulation; Aurc: -7.1 +/- 5.1 vs. Alrc: 6.9 +/- 3.5%). During the latter maneuvers the upper rib cage deflated along the relationship between upper rib cage dimensions and pleural pressure obtained during passive deflation, whereas the lower rib cage inflated close to the relationship between lower rib cage dimensions and abdominal pressure obtained during passive inflation. The latter relationship is expected to differ between costal and crural stimulation, since costal action has both an appositional and insertional component and crural action only has an appositional component. The difference between costal and crural stimulation, however, was relatively small, and the slopes were only slightly steeper for the costal than for the crural stimulation (2.9 +/- 1.2 vs. 2.2 +/- 1.0%.(ABSTRACT TRUNCATED AT 250 WORDS)

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Chest wall shape during forced expiratory maneuvers

Journal of Applied Physiology ◽

10.1152/jappl.1981.50.1.84 ◽

1981 ◽

Vol 50 (1) ◽

pp. 84-93 ◽

Cited By ~ 11

Author(s):

C. G. Melissinos ◽

M. Goldman ◽

E. Bruce ◽

E. Elliott ◽

J. Mead

Keyword(s):

Volume Change ◽

Vital Capacity ◽

Vertical Motion ◽

Normal Subjects ◽

Sectional Area ◽

Potential Mechanism ◽

Cross Sectional ◽

Rib Cage ◽

Abdominal Shape ◽

Shape Changes

Abdominothoracic shape during the forced vital capacity was studied in 10 normal subjects using magnetometers to monitor anteroposterior diameters at the level of the manubrium, xiphoid, and epigastrium, lateral rib cage diameter at the xiphoid level, and vertical motion of the rib cage. Thoracic cross-sectional area change at the xiphoid level was found to lag lung volume change, due to an early paradoxical increase (or lack of change), of lower anteroposterior rib cage diameter. To the extent that the resulting rib cage deformation can influence the pleural pressure gradient, the observed shape changes provide a potential mechanism for early preferential emptying of the upper lobes and later more homogeneous emptying in forced, compared to slow, vital capacity maneuvers. Comparisons of shape changes during Valsalva and abdominal expiratory ("expulsive") maneuvers suggest that lower rib cage deformation may not simply be due to the action of rib cage muscles affecting predominantly the lateral rib cage but rather the results of diaphragmatic activity and the influence of abdominal shape on the lower rib cage.

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Estimates of ventilation from body surface measurements in unrestrained subjects

Journal of Applied Physiology ◽

10.1152/jappl.1986.61.3.1114 ◽

1986 ◽

Vol 61 (3) ◽

pp. 1114-1119 ◽

Cited By ~ 33

Author(s):

F. D. McCool ◽

K. B. Kelly ◽

S. H. Loring ◽

I. A. Greaves ◽

J. Mead

Keyword(s):

Linear Regression ◽

Tidal Volume ◽

Multiple Linear Regression ◽

Body Surface ◽

Cross Sectional Area ◽

Axial Displacement ◽

Sectional Area ◽

Cross Sectional ◽

Linear Dimensions ◽

Surface Measurements

To make estimates of ventilation from measurements of body surface movements in unrestrained subjects, we measured changes in linear dimensions and cross-sectional areas of the rib cage (RC) and abdomen (AB) of six healthy unrestrained subjects during a variety of maneuvers. RC and AB anteroposterior diameters and abdominal length in the cephalocaudal axis (axial displacement) were measured with magnetometers, and RC and AB cross-sectional areas were measured with a respiratory inductance plethysmograph. Flow was measured at the mouth with a pneumotachograph and integrated electrically to give volume. Volume and body surface measurements were analyzed by multiple linear regression. Addition of the axial measurements to either the anteroposterior dimensions or cross-sectional areas of RC and AB improved estimates of tidal volume in all subjects (P less than 0.01). With measurements of axial displacement and cross-sectional area of the RC and AB, tidal volume could be reliably estimated to within 20% of actual ventilation. We conclude that measurement of axial displacements improves estimates of ventilation in unrestrained subjects.

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Opening the Nasal Valve with External Dilators Reduces Congestive Symptoms in Normal Subjects

American Journal of Rhinology ◽

10.1177/194589240501900217 ◽

2005 ◽

Vol 19 (2) ◽

pp. 215-219 ◽

Cited By ~ 11

Author(s):

Jenny Latte ◽

David Taverner

Keyword(s):

Visual Analog Scale ◽

Nasal Congestion ◽

Normal Subjects ◽

Cross Sectional Area ◽

Ordinal Scale ◽

Sectional Area ◽

Nasal Valve ◽

Analog Scale ◽

Cross Sectional ◽

Valve Area

Background We examined whether the use of two different external nasal dilator devices influenced the size of the nasal valve area and symptoms of nasal congestion. Methods This was a randomized blind-allocation, open three-way crossover study of Breathe Right, Side Strip Nasal Dilators, and placebo. We studied 12 healthy subjects (10 female, 2 male; age range 26–56 years). Measures of total volume and total minimum cross-sectional area were collected. Subjective symptoms were collected using a visual analog scale and an ordinal scale. Results With both products, there was significant increase in the size of the minimum cross-sectional area compared to placebo, p = 0.004. This is supported by the decrease in the subjective reports of congestion; on the visual analog scale, compared to placebo p = 0.012 and the ordinal scale, compared to placebo, p = 0.004. Conclusion Both devices significantly increase the size of the nasal valve area and reduce congestion in normal subjects.

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An Anechoic Space at the Carpal Tunnel Inlet is a Consistent Ultrasonographic Entity which Accommodates Tendon Displacement during Finger Flexion

The Journal of Hand Surgery (Asian-Pacific Volume) ◽

10.1142/s2424835516500223 ◽

2016 ◽

Vol 21 (02) ◽

pp. 222-228

Author(s):

Bing Howe Lee ◽

Chin Hock Goh ◽

Amitabha Lahiri

Keyword(s):

Median Nerve ◽

Carpal Tunnel ◽

Prevalence Rate ◽

Normal Subjects ◽

Cross Sectional Area ◽

Sectional Area ◽

Cross Sectional ◽

Finger Flexion ◽

Normal Individuals ◽

Asymptomatic Volunteers

Background: We consistently observed the presence of anechoic spaces on standard ultrasonographic imaging of the carpal tunnel inlet in normal subjects. These spaces change in size during finger flexion and have not been characterized in a large sample of normal individuals. Ultrasonographic quantification of these spaces may indicate the available space in the region of the carpal tunnel, which allows the normal motion of tendons and the median nerve. Methods: Transverse ultrasonographic images of the carpal tunnel inlet from 33 asymptomatic volunteers were obtained at Position A (fingers in extension) and B (fingers in flexion). Cross-sectional area (CSA), perimeter and position of anechoic space relative to median nerve were recorded. Results: Analysis showed a 75.4% prevalence rate of a single anechoic space. Two discrete patterns were observed. 89.1% had a decrease in CSA and perimeter of anechoic space from Position A to B while 10.9% exhibited an increase. Mean position of the anechoic space is ulnar (7.49 ± 3.57 mm) and dorsal (2.18 ± 1.28 mm) to the median nerve. Conclusions: A consistent anechoic space at the carpal tunnel inlet is seen in 75.4% of normal hands and can be quantified (cross sectional area 11.75 ± 7.36 mm2). It allows for the accommodation of flexor tendons during finger flexion.

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Protocol-dependence of middle cerebral artery dilation to modest hypercapnia

Applied Physiology Nutrition and Metabolism ◽

10.1139/apnm-2021-0220 ◽

2021 ◽

Author(s):

Baraa K Al-Khazraji ◽

Sagar Buch ◽

Mason Kadem ◽

Brad J Matushewski ◽

Kambiz Norozi ◽

...

Keyword(s):

Steady State ◽

Middle Cerebral Artery ◽

Cerebral Artery ◽

Blood Velocity ◽

Cross Sectional Area ◽

Cerebrovascular Reactivity ◽

7 Tesla ◽

Sectional Area ◽

Cross Sectional ◽

End Tidal

There is a need for improved understanding of how different cerebrovascular reactivity (CVR) protocols affect vascular cross-sectional area (CSA) when measures of vascular CSA are not feasible. In human participants, we delivered ~±4mmHg end-tidal partial pressure of CO2 (PETCO2) relative to baseline through controlled delivery, and measured changes in middle cerebral artery (MCA) cross-sectional area (CSA; 7 Tesla MRI), blood velocity (transcranial Doppler and Phase contrast MRI), and calculated CVR based on: a 3-minute steady-state (+4mmHg PETCO2) and a ramp (-3 to +4mmHg of PETCO2). We observed that 1) the MCA did not dilate during the ramp protocol (slope for CSA across time P>0.05; R2 = 0.006), but did dilate by ~7% during steady-state hypercapnia (P<0.05), and 2) MCA blood velocity CVR was not different between ramp and steady-state hypercapnia protocols (ramp: 3.8±1.7 vs. steady-state: 4.0±1.6 cm/s/mmHg), although calculated MCA blood flow CVR was ~40% greater during steady-state hypercapnia than during ramp (P<0.05), the discrepancy due to MCA CSA changes during steady-state hypercapnia. We propose that a ramp model, across a delta of -3 to +4mmHg PETCO2, may provide one alternative approach to collecting CVR measures in young adults with TCD when CSA measures are not feasible. Novelty • We optimized a magnetic resonance imaging sequence to measure dynamic middle cerebral artery (MCA) cross-sectional area (CSA) • A ramp model of hypercapnia elicited similar MCA blood velocity reactivity as the steady-state model while maintaining MCA CSA

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Protocol-dependence of middle cerebral artery dilation to modest hypercapnia

10.1101/2021.03.11.434655 ◽

2021 ◽

Author(s):

Baraa K. Al-Khazraji ◽

Sagar Buch ◽

Mason Kadem ◽

Brad J. Matushewski ◽

Kambiz Norozi ◽

...

Keyword(s):

Steady State ◽

Middle Cerebral Artery ◽

Cerebral Artery ◽

Blood Velocity ◽

Cross Sectional Area ◽

Cerebrovascular Reactivity ◽

7 Tesla ◽

Sectional Area ◽

Cross Sectional ◽

End Tidal

AbstractThere is a need for improved understanding of how different cerebrovascular reactivity (CVR) protocols affect vascular cross-sectional area (CSA) when measures of vascular CSA are not feasible. In human participants, we delivered ~±4mmHg end-tidal partial pressure of CO2 (PETCO2) relative to baseline through controlled delivery, and measured changes in middle cerebral artery (MCA) cross-sectional area (CSA; magnetic resonance imaging (7 Tesla MRI)), blood velocity (transcranial Doppler and Phase contrast MRI), and calculated CVR based on steady-state versus a ramp protocol during two protocols: a 3-minute steady-state (+4mmHg PETCO2) and a ramp (delta of −3 to +4mmHg of PETCO2). We observed that 1) the MCA did not dilate during the ramp protocol, but did dilate during steady-state hypercapnia, and 2) MCA blood velocity CVR was similar between ramp and steady-state hypercapnia protocols, although calculated MCA blood flow CVR was greater during steady-state hypercapnia than during ramp, the discrepancy due to MCA CSA changes during steady-state hypercapnia. Due to the ability to achieve similar levels of MCA blood velocity CVR as steady-state hypercapnia, the lack of change in MCA cross-sectional area, and the minimal expected change in blood pressure, we propose that a ramp model, across a delta of ~−3 to +4mmHg PETCO2, may provide one alternative approach to collecting CVR measures in young adults with TCD when CSA measures are not feasible.

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Modeling of Subcooled Flow Boiling with Nanoparticles under the Influence of a Magnetic Field

Symmetry ◽

10.3390/sym11101275 ◽

2019 ◽

Vol 11 (10) ◽

pp. 1275 ◽

Cited By ~ 23

Author(s):

Mohammad Abdollahzadeh Jamalabadi ◽

Milad Ghasemi ◽

Rezvan Alamian ◽

Somchai Wongwises ◽

Masoud Afrand ◽

...

Keyword(s):

Magnetic Field ◽

Froude Number ◽

Volume Fraction ◽

Flow Boiling ◽

Fluid Velocity ◽

Cross Sectional Area ◽

Sectional Area ◽

Cross Sectional ◽

Subcooled Flow Boiling ◽

Subcooled Flow

Subcooled flow boiling is one of the major issues in the nuclear and power generation industries. If the fluid inlet temperature in the boiling area is less than the boiling temperature, the boiling process is called subcooled boiling. The symmetry of a physical system is a constant property of the system and is fixed by deformation. Using magnetohydrodynamic (MHD) forces and broken symmetry induced by nanosized particles, fluid and thermal systems can be more controlled. In this study, the effect of a magnetic field and nanoparticles on subcooled flow boiling in a vertical tube was investigated. For this purpose, a one-dimensional numerical code was used to simulate the flow and variations of various parameters that have been investigated and evaluated. The results showed that as the flow entered the heated area, the vapor volume fraction, Froude number, fluid cross-sectional area forces, mixture velocity, fluid velocity, bubble departure diameter, liquid and vapor Reynolds numbers, squared ratio of the Froude number to the Weber number, and fluid cross-sectional area forces coefficient increased. In the same region, the Eötvös number, root mean square (RMS) of the fluid cross-sectional area force, sound velocity, liquid superficial velocity, critical tube diameter, bubble departure frequency, and density of the active nucleation site were reduced. It was also observed that after the heated area and under the influence of the magnetic field and the nanoparticles, the values of the vapor volume fraction, Froude number, fluid cross-sectional area force, mixture velocity, fluid velocity, vapor, liquid Reynolds number, and squared ratio of the Froude number to the Weber number were decreased. Moreover, there was no significant effect on the Eötvös number, liquid superficial velocity, Taylor bubble Sauter mean diameter, bubble departure diameter, critical tube diameter, bubble departure frequency, or density of the active nucleation site.

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