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

Airway anesthesia effects on hypercapnic breathing pattern in humans

1983 ◽  
Vol 55 (2) ◽  
pp. 368-376 ◽  
Author(s):  
T. Y. Sullivan ◽  
P. L. Yu
Keyword(s):  
Airway Resistance ◽  
Vital Capacity ◽  
Breathing Pattern ◽  
Minute Ventilation ◽  
Normal Subjects ◽  
Inspiratory Time ◽  
Abrupt Increase ◽  
Thoracic Gas Volume ◽  
Before And After ◽  
Gas Volume

Minute ventilation (VE) and breathing pattern during an abrupt increase in fractional CO2 were compared in 10 normal subjects before and after airway anesthesia. Subjects breathed 7% CO2-93% O2 for 5 min before and after inhaling aerosolized lidocaine. As a result of airway anesthesia, VE and tidal volume (VT) were greater during hypercapnia, but there was no effect on inspiratory time (TI). Therefore, airway anesthesia produced an increase in mean inspiratory flow (VT/TI) during hypercapnia. The increase in VT/TI was compatible with an increase in neuromuscular output. There was no effect of airway anesthesia on the inspiratory timing ratio or the shape and position of the curve relating VT and TI. We also compared airway resistance (Raw), thoracic gas volume, forced vital capacity, forced expired volume at 1s, and maximum midexpiratory flow rate before and after airway anesthesia. A small (0.18 cmH2O X l-1 X s) decrease in Raw occurred after airway anesthesia that did not correlate with the effect of airway anesthesia on VT/TI. We conclude that airway receptors accessible to airway anesthesia play a role in hypercapnic VE.

Partitioning of pulmonary resistance in calves

1987 ◽  
Vol 62 (5) ◽  
pp. 1826-1831 ◽  
Author(s):  
P. Gustin ◽  
F. Lomba ◽  
J. Bakima ◽  
P. Lekeux ◽  
K. P. Van de Woestijne
Keyword(s):  
Airway Resistance ◽  
Transpulmonary Pressure ◽  
Small Airways ◽  
Alveolar Pressure ◽  
Pulmonary Resistance ◽  
Lung Volumes ◽  
Tissue Resistance ◽  
Pleural Surface ◽  
Pressure Changes ◽  
Central Airway

Nine right apical lobes of healthy Friesian calves and 10 right apical lobes of double-muscled calves of Belgian White and Blue (BWB) breed were suspended in an airtight box, inflated at a constant transpulmonary pressure (Ptp), and subjected to quasi-sinusoidal pressure changes (amplitude: 0.5 kPa) at a frequency of 30 cycles/min. Lobar resistance (RL) was partitioned at six different lung volumes into three components: central airway resistance (Rc), small airway resistance (Rp), and tissue resistance (Rt). Pressure in small airways (2–3 mm ID) was measured with a retrograde catheter. Alveolar pressure was sampled in capsules glued onto the punctured pleural surface. RL was minimal at values of Ptp comprised between 0.5 and 0.7 kPa and increased at higher and lower values of Ptp. At a Ptp of 0.5 kPa, Rc, Rp, and Rt represented 30, 15, and 55% of RL, respectively, in Friesian calves and 25, 25, and 50% in BWB calves. Rp increased markedly at low lung volumes. Rt was responsible for the increase of RL at high Ptp. Rc tended to decrease at high Ptp. The significantly higher values of Rp in BWB calves (P less than 0.05) might explain the sensitivity of this breed to severe bronchopneumonia.

Heart Rate Signal Decomposition

2000 ◽  
Vol 39 (02) ◽  
pp. 200-203
Author(s):  
H. Mizuta ◽  
K. Yana
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Pressure Change ◽  
Normal Subjects ◽  
Signal Decomposition ◽  
Large Individual ◽  
Heart Rate Fluctuations ◽  
Type Pattern ◽  
Signal Cancellation ◽  
Pressure Changes

Abstract:This paper proposes a method for decomposing heart rate fluctuations into background, respiratory and blood pressure oriented fluctuations. A signal cancellation scheme using the adaptive RLS algorithm has been introduced for canceling respiration and blood pressure oriented changes in the heart rate fluctuations. The computer simulation confirmed the validity of the proposed method. Then, heart rate fluctuations, instantaneous lung volume and blood pressure changes are simultaneously recorded from eight normal subjects aged 20-24 years. It was shown that after signal decomposition, the power spectrum of the heart rate showed a consistent monotonic 1/fa type pattern. The proposed method enables a clear interpretation of heart rate spectrum removing uncertain large individual variations due to the respiration and blood pressure change.

scholarly journals Air Movement in Snow Due to Windpumping

1989 ◽  
Vol 35 (120) ◽  
pp. 209-213 ◽  
Author(s):  
S.C. Colbeck
Keyword(s):  
Pore Space ◽  
Barometric Pressure ◽  
Surface Flows ◽  
Wind Speeds ◽  
Compression And Expansion ◽  
Strong Winds ◽  
Pressure Changes ◽  
Low Amplitude ◽  
Pressure Perturbations ◽  
Rapid Pressure

Abstract Strong winds can disrupt the thermal regime in seasonal snow because of the variation in surface pressure associated with surface features like dunes and ripples. Topographical features of shorter wavelengths produce stronger surface flows, but the flow decays rapidly with depth. Longer-wavelength features produce weaker surface flows but the flow decays more slowly with depth. The flow may only be strong enough to disrupt the temperature field for features of wavelengths on the scale of meters or tens of meters at wind speeds of 10 m/s or more. Other possible causes of windpumping have been examined but they do not appear to be as significant. Rapid pressure perturbations due to turbulence produce very little displacement of the air because of the high frequency and low amplitude. Barometric pressure changes cause compression and expansion of the air in the pore space, but the rate is too low to have much effect.

A critical role for central vasopressin in regulation of fever during bacterial infection

1992 ◽  
Vol 263 (6) ◽  
pp. R1235-R1240
Author(s):  
R. A. Cridland ◽  
N. W. Kasting
Keyword(s):  
Body Temperature ◽  
Arginine Vasopressin ◽  
Continuous Measurement ◽  
Critical Role ◽  
Experimental Models ◽  
Bacterial Endotoxins ◽  
Chronic Infusion ◽  
Live Bacteria ◽  
The Brain

Previous investigations on the antipyretic properties of arginine vasopressin have used bacterial endotoxins or pyrogens to induce fever. Because these experimental models of fever fail to mimic all aspects of the responses to infection, we felt it was important to examine the role of endogenously released vasopressin as a neuromodulator in febrile thermoregulation during infection. Therefore the present study examines the effects of chronic infusion of a V1-receptor antagonist or saline (via osmotic minipumps into the ventral septal area of the brain) on a fever induced by injection of live bacteria. Telemetry was used for continuous measurement of body temperature in the awake unhandled rat. Animals infused with the V1-antagonist exhibited fevers that were greater in duration compared with those of saline-infused animals. These results support the hypothesis that vasopressin functions as an antipyretic agent or fever-reducing agent in brain. Importantly, they suggest that endogenously released vasopressin may play a role as a neuromodulator in natural fever.

End-expiratory and tidal volumes measured in conscious mice using single projection x-ray images

2008 ◽  
Vol 104 (2) ◽  
pp. 521-533 ◽  
Author(s):  
Stephen J. Lai-Fook ◽  
Pamela K. Houtz ◽  
Yih-Loong Lai
Keyword(s):  
Body Temperature ◽  
Lung Volume ◽  
Airway Resistance ◽  
X Rays ◽  
Airway Closure ◽  
Exposure Phase ◽  
X Ray ◽  
Total Lung Volume ◽  
Aerosol Exposure ◽  
Lung Area

The evaluation of airway resistance (Raw) in conscious mice requires both end-expiratory (Ve) and tidal volumes (Vt) (Lai-Fook SJ and Lai YL. J Appl Physiol 98: 2204–2218, 2005). In anesthetized BALB/c mice we measured lung area (AL) from ventral-to-dorsal x-ray images taken at FRC (Ve) and after air inflation with 0.25 and 0.50 ml (ΔVL). Total lung volume (VL) described by equation: VL = ΔVL + VFRC = KAL1.5 assumed uniform (isotropic) inflation. Total VFRC averaged 0.55 ml, consisting of 0.10 ml tissue, 0.21 ml blood and 0.24 ml air. K averaged 1.84. In conscious mice in a sealed box, we measured the peak-to-peak box pressure excursions (ΔPb) and x-rays during several cycles. K was used to convert measured AL1.5 to VL values. We calculated Ve and Vt from the plot of VL vs. cos(α − φ). Phase angle α was the minimum point of the Pb cycle to the x-ray exposure. Phase difference between the Pb and VL cycles (φ) was measured from ΔPb values using both room- and body-temperature humidified box air. A similar analysis was used after aerosol exposures to bronchoconstrictor methacholine (Mch), except that φ depended also on increased Raw. In conscious mice, Ve (0.24 ml) doubled after Mch (50–125 mg/ml) aerosol exposure with constant Vt, frequency (f), ΔPb, and Raw. In anesthetized mice, in addition to an increased Ve, repeated 100 mg/ml Mch exposures increased both ΔPb and Raw and decreased f to apnea in 10 min. Thus conscious mice adapted to Mch by limiting Raw, while anesthesia resulted in airway closure followed by diaphragm fatigue and failure.

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.

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.

scholarly journals A versatile telemetry system for continuous measurement of heart rate, body temperature and locomotor activity in free-ranging ruminants

2010 ◽  
Vol 1 (1) ◽  
pp. 75-85 ◽  
Author(s):  
Claudio Signer ◽  
Thomas Ruf ◽  
Franz Schober ◽  
Gerhard Fluch ◽  
Thomas Paumann ◽  
...  
Keyword(s):  
Heart Rate ◽  
Locomotor Activity ◽  
Body Temperature ◽  
Continuous Measurement ◽  
Telemetry System ◽  
Free Ranging

Estimation of Alveolar Pressure During Speech Using Direct Measures of Tracheal Pressure

1999 ◽  
Vol 42 (5) ◽  
pp. 1136-1147 ◽  
Author(s):  
Eileen M. Finnegan ◽  
Erich S. Luschei ◽  
Henry T. Hoffman
Keyword(s):  
Respiratory System ◽  
Airway Resistance ◽  
Sudden Change ◽  
Vocal Folds ◽  
Sentence Production ◽  
Lower Airway ◽  
Alveolar Pressure ◽  
Elastic Recoil ◽  
Pressure Source ◽  
Tracheal Pressure

The pressure in the alveoli of the lungs, created by the elastic recoil of the lungs and respiratory muscle activity, is referred to as alveolar pressure (P a ). The extent to which tracheal pressure (P t ) approximates P a depends on the resistance to airflow offered by structures above and below the point at which tracheal pressure is measured. An understanding of the relationship among P a , P t , and upper and lower airway resistance, and how these values fluctuate during speech, could aid in interpretation and modeling of speech aerodynamics. The purpose of this study was to (a) obtain values for lower airway resistance (R law ), (b) use these R law values to estimate P a during speech, and (c) quantify the degree to which P t approximates P a during production of voiced and voiceless sounds, in comparison to inhalation. In addition, the results were discussed in terms of the degree to which the respiratory system functions as a pressure source. Tracheal pressure (obtained with tracheal puncture) and airflow were measured during sentence production in 6 subjects. Using a technique introduced in this paper, R law was determined from measures of tracheal pressure and flow obtained during a sudden change in upper airway resistance because of release of a voiceless plosive. Mean R law values ranged from 0.14 to 0.32 kPa/(l/s). Each subject's mean R law was used to derive a time-varying measure of P a during speech from continuous measures of tracheal pressure and airflow. P t was approximately 95% of P a during phonation (i.e., when the vocal folds were adducted), 75% of P a during release of the voiceless stop consonant /p/, and 55% of P a during inhalation (i.e., when the vocal folds were abducted). Therefore, the degree to which the respiratory system functioned as an ideal pressure source varied during speech. The ability to estimate P a provides a measure of the pressure produced by the respiratory system that is not influenced by laryngeal activity.

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