A noninvasive technique for measurement of changes in specific airway resistance

1979 ◽  
Vol 46 (2) ◽  
pp. 399-406 ◽  
Author(s):  
B. E. Pennock ◽  
C. P. Cox ◽  
R. M. Rogers ◽  
W. A. Cain ◽  
J. H. Wells
Keyword(s):  
Airway Resistance ◽  
Noninvasive Technique ◽  
Bronchial Challenge ◽  
Specific Airway Resistance ◽  
Thoracic Gas Volume ◽  
Wide Range ◽  
Airways Resistance ◽  
Pleural Catheter ◽  
Acute Changes ◽  
Gas Volume

A simple noninvasive technique for measuring specific airway resistance (airway resistance X thoracic gas volume) in unanesthetized guinea pigs is described. Specific airway resistances measured by this technique correlated well (r = 0.81) with the resistances obtained using a pleural catheter pressure measurement over a wide range of airway resistances. This range of resistances was generated by exposing the pigs to an aerosolized histamine bronchial challenge. The average specific airways resistance in unchallenged pigs was 1.24 +/- 3.47 cmH2O/s, somewhat lower than found by others, probably reflecting in part our larger pigs and in part some uncertainty in the absolute value of resistance inherent in our measurement technique. This technique is particularly useful in bronchial challenge experiments because of its sensitivity to acute changes in airway resistance.

Body plethysmographic measurement of thoracic gas volume without panting against a shutter

1996 ◽  
Vol 81 (2) ◽  
pp. 1007-1011 ◽  
Author(s):  
A. Agrawal ◽  
K. P. Agrawal
Keyword(s):  
Airway Resistance ◽  
Normal Subjects ◽  
Dilution Method ◽  
Chronic Obstructive ◽  
Obstructive Pulmonary Disease ◽  
Restrictive Lung Disease ◽  
Asthmatic Patients ◽  
Specific Airway Resistance ◽  
Thoracic Gas Volume ◽  
Gas Volume

When a subject breathes through a pneumotachograph in a body box, the measured value of specific airway resistance (sRaw1) is equal to the product of thoracic gas volume (TGV) and the sum of the airway resistance (Raw) and the instrument resistance (Rins). If an additional resistance (Radd) is put in the breathing path, the measured specific, airway resistance (sRaw2) exceeds sRaw1 by the product of TGV and Radd and can be used for determining TGV. With the use of a device increasing Rins by a known amount (Radd) during normal breathing, sRaw1 and sRaw2 were measured in 3 normal subjects, 16 asthmatic patients, 2 patients with chronic obstructive pulmonary disease, and 1 patient with restrictive lung disease from the slopes of the x-y plots of airflow vs. box signals obtained before and after adding Radd. TGV was calculated by dividing (sRaw2-sRaw1) bu Radd. We also determined subjects' TGV by the panting method of A. B. DuBois, S. Y. Botelho, G. N. Bedell, and J. H. Comroe, Jr. (J. Clin. Invest. 35: 322–326, 1956) and functional residual capacity by the helium-dilution method. The results of the new method were quite reproducible (coefficient of variation = 5.6) and equivalent to those obtained by the other two methods.

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.

scholarly journals Variation between observers in the estimation of airway resistance and thoracic gas volume.

Thorax ◽  
1977 ◽  
Vol 32 (1) ◽  
pp. 67-70 ◽  
Author(s):  
P W Lord ◽  
A G Brooks ◽  
J M Edwards
Keyword(s):  
Airway Resistance ◽  
Thoracic Gas Volume ◽  
Gas Volume

Effect of a previous deep inspiration on airway resistance in man

1961 ◽  
Vol 16 (4) ◽  
pp. 717-719 ◽  
Author(s):  
Jay A. Nadel ◽  
Donald F. Tierney
Keyword(s):  
Airway Resistance ◽  
Healthy Adult ◽  
Transpulmonary Pressure ◽  
The Body ◽  
Deep Inspiration ◽  
Thoracic Gas Volume ◽  
Before And After ◽  
Residual Capacity ◽  
Gas Volume ◽  
Control State

We measured airway resistance and thoracic gas volume by the body plethysmograph technique, and transpulmonary pressure in seven healthy, adult subjects, before and after induction of bronchoconstriction. A deep inspiration never altered airway resistance, measured at functional residual capacity in the control state, but always reduced it for 1—2 min when bronchoconstriction was present. Discrepancies in data published on airway resistance may be due to use of methods which require a deep inspiration, or to occurrence of a spontaneous deep inspiration shortly before the test. Submitted on January 13, 1961

A new apparatus for the accurate measurement of airway resistance in infancy

1977 ◽  
Vol 43 (1) ◽  
pp. 155-159 ◽  
Author(s):  
J. Stocks ◽  
N. M. Levy ◽  
S. Godfrey
Keyword(s):  
Body Temperature ◽  
Linear Response ◽  
Airway Resistance ◽  
Flow Rates ◽  
Potential Source ◽  
Thoracic Gas Volume ◽  
Average Coefficient ◽  
New Apparatus ◽  
Gas Volume ◽  
Source Of Error

A new heated rebreathing system has been developed for the measurement of thoracic gas volume (TGV) and airway resistance (Raw) in infants by the plethysmographic technique. The apparatus has a linear response to flow rates between 0–160 ml-s-1, a dead space of 12 ml and a resistance of 5 cmH2O–1–1-S-1 at a flow rate of 60 ml-s-1. The inclusion of pneumatically operated valves in the apparatus is a major improvement over previous methods of occlusion for TGV measurements. The infant is allowed to rebreathe saturated gas at body temperature through the heated system, thus overcoming a potential source of error when measuring Raw in infants. Using this apparatus, the average coefficient of variation was 3.7% for TGV and 5.9% for Raw.

Decreased Specific Airway Conductance in Infant Apnea

PEDIATRICS ◽  
1985 ◽  
Vol 76 (2) ◽  
pp. 232-235
Author(s):  
Lily C. Kao ◽  
Thomas G. Keens
Keyword(s):  
Airway Resistance ◽  
Respiratory Control ◽  
Pulmonary Mechanics ◽  
Quiet Breathing ◽  
Airway Narrowing ◽  
Pulmonary Compliance ◽  
Thoracic Gas Volume ◽  
Airway Tone ◽  
Gas Volume ◽  
Airway Conductance

A disorder of respiratory control is the suspected etiology in a majority of infants with apnea. Although neurologic control of breathing has been evaluated in infants surviving an apneic episode, pulmonary mechanics have not been previously measured. Pulmonary mechanics were measured during sleep in ten infants with apnea, aged 45.4 ± 1.4 (SE) weeks postconception, and 13 control infants, aged 42.0 ± 0.8 weeks postconception. Infant apnea patients were defined as those having at least one episode of cyanosis, limpness, and apnea requiring vigorous stimulation or resuscitation to restore normal breathing, and in whom no treatable etiology could be found. Thoracic gas volume, airway resistance, and specific airway conductance were measured in an infant body pressure plethysmograph during quiet breathing. Dynamic pulmonary compliance was measured in six infants using an esophageal balloon. Specific airway conductance was decreased in infants with apnea compared with control infants (P < .05). Thoracic gas volume, airway resistance, and dynamic pulmonary compliance values were comparable with those of control infants. These data suggest that airway narrowing or abnormal control of airway tone during sleep may contribute to apnea in some infants.

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