Frequency response of the chest: modeling and parameter estimation

1975 ◽  
Vol 39 (4) ◽  
pp. 523-534 ◽  
Author(s):  
R. Peslin ◽  
J. Papon ◽  
C. Duviver ◽  
J. Richalet
Keyword(s):  
Frequency Response ◽  
Gas Flow ◽  
Airway Resistance ◽  
Mechanistic Model ◽  
Normal Subjects ◽  
Order Equation ◽  
Mean Values ◽  
Tissue Compliance ◽  
Linear Differential ◽  
Gas Compressibility

The frequency response of the respiratory system was studied in the range from 3 to 70 Hz in 15 normal subjects by applying sinusoidal pressure variations around the chest and measuring gas flow at the mouth. The observed input-output relationships were systematically compared to those predicted on the basis of linear differential equations of increasing order. From 3 to 20 Hz the behavior of the system was best described by a 3rd-order equation, and from 3 to 50 Hz by a 4th-order one. A mechanistic model of the 4th order, featuring tissue compliance (Ct), resistance (Rt) and inertance (It), alveolar gas compressibility (Cg) and airway resistance (Raw), and inertance (Iaw) was developed. Using that model, the following mean values were found: Ct = 2.08–10(-2)1-hPa-1 (1 hPa congruent to 1 cm of water); Rt = 1.10-hPa-1(-1)-s; It = 0.21–10(-2)hPa-1(-1)-s2; Raw = 1.35-hPa-1(-1)-s; Iaw = 2.55–10(-2)hPa-1(-1)-s2. Additional experiments devised to validate the model were reasonably successful, suggesting that the physical meaning attributed to the coefficients was correct. The validity of the assumptions and the physiological meaning of the coefficients are discussed.

Respiratory transfer impedances with pressure input at the mouth and chest

1986 ◽  
Vol 61 (1) ◽  
pp. 81-86 ◽  
Author(s):  
R. Peslin ◽  
C. Gallina ◽  
C. Duvivier
Keyword(s):  
Chest Wall ◽  
Network Model ◽  
Airway Resistance ◽  
Normal Subjects ◽  
Respiratory Resistance ◽  
Pressure Flow ◽  
Transfer Impedance ◽  
Tissue Compliance ◽  
Practical Conclusion ◽  
The Relationship

Two methods of measuring respiratory transfer impedance (Ztr) were compared in 14 normal subjects, from 4 to 30 Hz, 1) studying the relationship between transrespiratory pressure (Prs) and flow at the chest when varying pressure at the mouth (Ztrm) and 2) studying the relationship between Prs and flow at the mouth when varying pressure around the chest wall (Ztrw). The similarity of the two relationships was expected on the basis of a T-network model. Almost identical phase responses were obtained from the two methods. Pressure-flow ratios were slightly larger for Ztrw than for Ztrm, but differences did not exceed 2% on average in 11 of 14 subjects. When the data were analyzed with the six-coefficient model proposed by DuBois et al. (J. Appl. Physiol. 8: 587–594, 1956), similar values were found for tissue compliance and tissue inertance but slightly different values for gaseous inertance in the airways (1.97 +/- 0.35 X 10(-2) cmH2O X l-1 X s2 for Ztrw vs. 1.73 +/- 0.26 for Ztrm; P less than 0.01). Similar results were also found for total respiratory resistance but with a slightly larger contribution of airway resistance for Ztrw (64 +/- 14 vs. 57 +/- 10%; P less than 0.05). As a practical conclusion it is recommended to measure Ztrw, which is technically much easier.

A COMPARISON OF TWO METHODS FOR MEASUREMENT OF ALDOSTERONE SECRETION RATE IN MAN

1966 ◽  
Vol 53 (2) ◽  
pp. 177-188 ◽  
Author(s):  
P. Lund-Johansen ◽  
T. Thorsen ◽  
K. F. Støa
Keyword(s):  
Urinary Excretion ◽  
Normal Subjects ◽  
Secretion Rate ◽  
Aldosterone Secretion ◽  
Simple Method ◽  
Mean Values ◽  
Pathological Conditions ◽  
Significant Difference ◽  
Derivative Method ◽  
The Mean

ABSTRACT A comparison has been made between (A), a relatively simple method for the measurement of aldosterone secretion rate, based on paper chromatography and direct densitometry of the aldosterone spot and (B) a more elaborate isotope derivative method. The mean secretion rate in 9 normal subjects was 112 ± 26 μg per 24 hours (method A) and 135 ± 35 μg per 24 hours (method B). The »secretion rate« in one adrenalectomized subject after the intravenous injection of 250 μg of aldosterone was 230 μg per 24 hours (method A) and 294 μg per 24 hours (method B). There was no significant difference in the mean values, and correlation between the two methods was good (r = 0.80). It is concluded that the densitometric method is suitable for clinical purposes as well as research, being more rapid and less expensive than the isotope derivative method. Method A also measures the urinary excretion of the aldosterone 3-oxo-conjugate, which is of interest in many pathological conditions. The densitometric method is obviously the less sensitive and a prerequisite for its use is an aldosterone secretion of 20—30 μg per 24 hours. Lower values are, however, rare in adults.

The Most Important Risk Factors for Carpal Tunnel Syndrome

2021 ◽  
Author(s):  
Ali Asghar Sharifi
Keyword(s):  
Risk Factors ◽  
Carpal Tunnel Syndrome ◽  
Carpal Tunnel ◽  
Clinical Symptoms ◽  
Normal Subjects ◽  
Shape Index ◽  
Mean Values ◽  
Tunnel Syndrome ◽  
Independent Risk Factors ◽  
Hand Length

Background: The aim of this study was to determine the risk factors for carpal tunnel syndrome and its relationship with the severity of the disease. Methods: A total of 131 patients with clinical symptoms of CTS and 131 normal subjects were enrolled, of whom 121 were female both in the CTS cases and the controls. All cases were electro diagnostically confirmed and assigned to three severity groups. BMI, wrist ratio, shape index, digit index and hand length/height ratio were measured in all participants. Mean values for each item were compared between cases and controls and severity subgroups. A logistic regression analysis was performed to determine independent CTS risk factors. Results: The mean values of BMI, wrist ratio and shape index were significantly higher in all CTS patients and females compared to controls, whereas in males only BMI and wrist ratio were higher. The patients in the mild severity subgroup had a significantly lower age and wrist ratio. BMI, wrist ratio and shape index were found to be independent risk factors of CTS development in all patients and females. Conclusion: Our study showed BMI, wrist ratio and shape index as independent risk factors for CTS. These findings are important anatomically and clinically and these are the risk factors of anatomical malfunction of the wrist in CTS.

Unrestrained video-assisted plethysmography: a noninvasive method for assessment of lung mechanical function in small animals

2008 ◽  
Vol 104 (1) ◽  
pp. 253-261 ◽  
Author(s):  
Jason H. T. Bates ◽  
John Thompson-Figueroa ◽  
Lennart K. A. Lundblad ◽  
Charles G. Irvin
Keyword(s):  
Airway Resistance ◽  
Breathing Pattern ◽  
Small Animals ◽  
Mechanical Function ◽  
Direct Link ◽  
Breathing Frequency ◽  
Noninvasive Method ◽  
Noninvasive Methods ◽  
Mean Values ◽  
Video Assisted

The assessment of lung mechanical function in small animals, particularly mice, is essential for investigations into the pathophysiology of pulmonary disease. The most accurate and specific methods for making this assessment are highly invasive and so provide data of questionable relevance to normality. By contrast, present noninvasive methods based on unrestrained plethysmography have no direct link to the mechanical properties of the lung. There is thus a need for a completely noninvasive method for determining lung mechanical function in small animals. In the present study, we demonstrate an extension of unrestrained plethysmography in which changes in lung volume are estimated via orthogonal video imaging of the thorax. These estimates are combined with the pressure swings recorded as mice breathe inside a heated and humidified chamber to yield an estimate of specific airway resistance (sRaw). We used this new technique, which we term “unrestrained video-assisted plethysmography” (UVAP), to measure sRaw in 11 BALB/c mice exposed to aerosols of saline, methacholine, and albuterol and obtained mean values of 0.71, 1.23 and 1.10 cmH2O·s, respectively. Mean breathing frequency was 4.3, 3.4, and 3.6 breaths/s, respectively, while the corresponding mean tidal volumes were 0.36, 0.44 and 0.37 ml, respectively. We conclude that UVAP, a noninvasive method, is able to provide usefully accurate estimates of sRaw and breathing pattern parameters in mice.

scholarly journals Assessing Airway Resistance Using Plethysmography as Lung Function Testing Among Asymptomatic Rheumatoid Arthritis Patients.

2021 ◽  
Vol 11 (6) ◽  
pp. 116-124
Author(s):  
Abdulrhman Mustafa Rasheed ◽  
Ahmed Fadlalla ◽  
Fadelelmoula Tarig ◽  
Wael F Asmaa Hegazy Alblowi ◽  
Fawaz Alshammari Saitah
Keyword(s):  
Rheumatoid Arthritis ◽  
Lung Function ◽  
Airway Resistance ◽  
Lung Function Testing ◽  
Mean Values ◽  
Pulmonary Manifestations ◽  
Medical City ◽  
Respiratory Mechanism ◽  
Function Testing ◽  
Airway Conductance

Pulmonary events in rheumatoid arthritis (RA) reflects the involvement of pleurae, lung interstitium, and airways. Overall, pulmonary manifestations are estimated to cause 10–20% of mortalities in RA. Respiratory system involvement as extra-articular presentations of RA is common among some Saudi patients. This study aims to evaluate specific airway conductance (sGaw), airway resistance (Raw), and specific airway resistance (sRaw), using plethysmography. Comparison for deployed methods is made by forced spirometer as an indicator for obstruction among patients with RA. The study sought to use the methods to enhance lung testing among RA patients. An analytical, hospital-based study was carried out at pulmonary function test laboratory, department of respiratory care King Saud Medical City (KSMC). RA patients were selected, with an age group of 18-75years. The tests for Forced spirometer and plethysmography were carried out to assess and analyze how the respiratory mechanism was impacted by the disease. Data collected was analyzed using Statistical Package for Social Sciences (SPSS), version 21. The obstructive and mixed ventilation patterns constituted 15%; the mean values of Raw and sRaw were significantly higher compared to mean values predicted for participants selected during the study, while sGaw was significantly lower compared to mean values predicted for participants selected. Monitoring of airway resistance parameters using plethysmography can be used as indicators of lung function testing among RA patients.

scholarly journals A Clinical Method for Estimating Laryngeal Airway Resistance during Vowel Production

1981 ◽  
Vol 46 (2) ◽  
pp. 138-146 ◽  
Author(s):  
Judith R. Smitheran ◽  
Thomas J. Hixon
Keyword(s):  
Airway Resistance ◽  
Great Promise ◽  
Adult Males ◽  
Clinical Tool ◽  
Vowel Production ◽  
Mean Values ◽  
Clinical Method ◽  
Oral Pressure ◽  
Airway Opening ◽  
Laryngeal Airway

A noninvasive clinical method for estimating laryngeal airway resistance during vowel production is described. Resistance is calculated from the ratio of translaryngeal pressure to translaryngeal flow, the first determined from measurement of oral pressure and the second determine from measurement of airway-opening flow made during the production of a specially designed utterance. Application of the method to the study of vowels resulted in a calculated mean laryngeal airway resistance of 35.7 cm H 2 O/LPS for 15 normal adult males. This resistance value is remarkably similar to mean values obtained in previous research using complex invasive experimental methods. Clinical use of the method is illustrated in case studies that highlight both evaluation and management potentials. It is concluded that the method proposed is clinically practical, that the data it provides are both valid and reliable, and that the method shows great promise of becoming a routine clinical tool for estimating laryngeal airway resistance during vowel production.

Stability of cerebrospinal fluid pH in chronic acid-base disturbances in blood

1965 ◽  
Vol 20 (3) ◽  
pp. 443-452 ◽  
Author(s):  
R. A. Mitchell ◽  
C. T. Carman ◽  
J. W. Severinghaus ◽  
B. W. Richardson ◽  
M. M. Singer ◽  
...  
Keyword(s):  
Metabolic Acidosis ◽  
Active Transport ◽  
Respiratory Acidosis ◽  
Normal Subjects ◽  
Respiratory Alkalosis ◽  
Regulation Of Respiration ◽  
Respiratory Drive ◽  
Acid Base ◽  
Peripheral Chemoreceptors ◽  
Mean Values

In chronic acid-base disturbances, CSF pH was generally within the normal limits (7.30–7.36 units, being the range including two standard deviations of 12 normal subjects). The mean values of CSF and arterial pHH, respectively, were: 1) metabolic alkalosis, 7.337 and 7.523; 2) metabolic acidosis, 7.315 and 7.350; 3) respiratory alkalosis, 7.336 and 7.485; and 4) respiratory acidosis (untreated), 7.314 and 7.382. Other investigators report similar values. The constancy of CSF pH cannot be explained by a poorly permeable blood-CSF barrier in chronic metabolic acidosis and alkalosis, nor can it be explained by respiratory compensation. It cannot be explained by renal compensation in respiratory alkalosis (high altitude for 8 days), although it may be explained by renal compensation in respiratory acidosis. The former three states suggest that active transport regulation of CSF pH is a function of the blood-CSF barrier. Since CSF pH is constant, so also must that portion of the respiratory drive originating in the superficial medullary respiratory chemoreceptors be constant. Ventilation changes in chronic acid-base disturbances thus may result from changes in the activity of peripheral chemoreceptors, in response to changes in arterial pH, arterial PO2, and possibly in neuromuscular receptors. regulation of respiration; medullary respiratory; chemoreceptors; peripheral chemoreceptors; metabolic acidosis and alkalosis; respiratory acidosis and alkalosis; active transport; blood-brain barrier; pregnancy Submitted on July 27, 1964

Bronchoconstriction in man following single deep inspirations

1963 ◽  
Vol 18 (1) ◽  
pp. 114-116 ◽  
Author(s):  
Thomas C. Lloyd
Keyword(s):  
Airway Resistance ◽  
Normal Subjects ◽  
Closed Glottis

Consistent small transient increases in airway resistance were observed to occur following maximal inspirations by a number of normal subjects. The same effect was also seen after merely attempting inspiration against a closed glottis, and both this and the response after deep inhalation were blocked by prior inhalation of a bronchodilator. An active bronchomotor mechanism is postulated for this response. Submitted on January 24, 1962

Airway resistance measurement during any breathing pattern in man

1959 ◽  
Vol 14 (1) ◽  
pp. 89-96 ◽  
Author(s):  
R. G. Bartlett ◽  
H. F. Brubach ◽  
R. C. Trimble ◽  
H. Specht
Keyword(s):  
Body Temperature ◽  
Airway Resistance ◽  
Breathing Pattern ◽  
Continuous Measurement ◽  
Normal Subjects ◽  
Pulmonary Diseases ◽  
Alveolar Pressure ◽  
Improved Method ◽  
Compression And Expansion ◽  
Pressure Changes

A broadly applicable method for the quantitative and continuous measurement of airway resistance in man is described. It permits the simultaneous measurement of air flow (breath velocity) and alveolar pressure during any breathing pattern. Alveolar pressure is calculated from body plethysmograph pressure (plethysmogram) changes coincident with the compression and expansion of lung air during expiration and inspiration, respectively. The plethysmograph interior is maintained at body temperature and complete H2O saturation. This avoids the errors in measurement due to plethysmograph pressure changes produced by temperature and humidity changes in the inspired and expired breath and also obviates the necessity of using only a panting type breathing pattern. Data on three normal subjects at near resting and near maximum breathing efforts are presented and discussed. This improved method, permitting airway resistance measurements during any breathing pattern, should find application in diagnosis and assessment of treatment of pulmonary diseases as well as in the investigation of several basic pulmonary function problems. Submitted on June 17, 1958

Force-velocity relationship of expiratory muscles in normal subjects

1982 ◽  
Vol 52 (4) ◽  
pp. 930-938 ◽  
Author(s):  
Y. Kikuchi ◽  
H. Sasaki ◽  
K. Sekizawa ◽  
K. Aihara ◽  
T. Takishima
Keyword(s):  
Respiratory Muscles ◽  
Normal Subjects ◽  
Contractile Element ◽  
Shortening Velocity ◽  
Mean Values ◽  
Significant Difference ◽  
Velocity Relationship ◽  
Force Velocity ◽  
Expiratory Muscles ◽  
Relationship Of

We examined the force-velocity relationship of the respiratory muscles in normal subjects under nearly isotonic conditions, taking into consideration the pleural pressure (Ppl) changes during maximum forced expirations (MFE). We used an electromagnetic valve (EMV) to select the Ppl value at the onset of mouth flow; and both a pressure reservoir and a variable resistance to control the Ppl changes after the opening of the EMV during MFE. To simulate isotonic conditions and to obtain the shortening velocity of the contractile element (CE), we mathematically corrected the velocity of the series elastic component (SEC), using a modified version of Hill's equation. Although the maximum tension at total lung capacity (TLC) [1,156 +/- 215 (SD) g/cm] was larger than that at functional residual capacity (FRC) (782 +/- 97 g/cm) there was no significant difference in the maximum shortening velocity, 3.4 +/- 1.0 and 3.2 +/- 0.8 circumference/s at TLC and FRC, respectively. The mean values of k (slope) for the SEC at TLC and FRC were 19 +/- 4 and 18 +/- 5 circumference-1, respectively, and they were not significantly different. We concluded that the force-velocity relationship of the expiratory muscles exhibited the same mechanical properties as that of the other skeletal muscles.

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