Measurement of pulmonary resistance and dynamic compliance with airway obstruction

1998 ◽  
Vol 85 (5) ◽  
pp. 1982-1988 ◽  
Author(s):  
Todd M. Officer ◽  
Riccardo Pellegrino ◽  
Vito Brusasco ◽  
Joseph R. Rodarte
Keyword(s):  
Dynamic Compliance ◽  
Normal Subjects ◽  
Dynamic Hyperinflation ◽  
Least Squares Regression ◽  
Pulmonary Resistance ◽  
Expiratory Resistance ◽  
Volume Curve ◽  
Pressure Volume Curve ◽  
Before And After ◽  
Inspiratory Resistance

We compared four algorithms by using least squares regression for determination of pulmonary resistance and dynamic elastance in subjects with emphysema, normal subjects, and subjects with asthma before and after bronchoconstriction. The four methods evaluated include 1) a single resistance and elastance, 2) separate resistances and elastances for each half breath, 3) separate inspiratory and expiratory resistances with a single elastance, and 4) separate inspiratory and expiratory resistances, an expiratory volume interaction term, and a single elastance. All methods gave comparable results in normal and asthmatic subjects. We found expiratory resistance was larger than inspiratory resistance in normal and asthmatic subjects during control conditions, but inspiratory resistance was higher than expiratory resistance in subjects who experienced severe bronchoconstriction in response to methacholine. In subjects who are flow limited, method 2 gives a higher inspiratory resistance than would be computed by assuming that the elastic pressure-volume curve passes through the zero-flow points. Methods 1 and 3 overestimate dynamic elastance and inspiratory resistance. Method 4appears to identify flow limitation and dynamic hyperinflation and gives a good measure of inspiratory resistance and dynamic elastance.

Application of an air-filled tube for measuring intraesophageal pressure

1994 ◽  
Vol 76 (5) ◽  
pp. 2106-2113 ◽  
Author(s):  
K. Shiraishi ◽  
M. Yaekashiwa ◽  
J. Nakagawa ◽  
T. Isawa ◽  
M. Motomiya
Keyword(s):  
Exponential Function ◽  
Dynamic Compliance ◽  
Esophageal Pressure ◽  
New Method ◽  
Pulmonary Resistance ◽  
Volume Curve ◽  
Pressure Volume Curve ◽  
Constant Rate ◽  
Significant Difference ◽  
Intraesophageal Pressure

We devised a new method for measuring esophageal pressure (Pes) with use of a flexible tube without a balloon at a constant rate of airflow through the tube into the esophagus (balloonless method). A study with 133Xe showed that the air that accumulated in the esophagus did not interfere with the measurement of Pes. We measured dynamic compliance (Cdyn) and pulmonary resistance (RL) with the balloonless method in 19 subjects and obtained a static deflation pressure-volume curve (P-V curve) in 10 other subjects. Cdyn was 0.243 +/- 0.099 l/cmH2O and RL was 1.52 +/- 0.42 cmH2O.l-1.s. In 6 of the 10 subjects, a P-V curve was also obtained with the balloon tube (balloon method). K, the index of compliance in the exponential function V = V0(1-e-KP) where V0 is volume at infinite pressure, was 0.136 +/- 0.040 cmH2O-1 with the balloonless method and 0.153 +/- 0.023 cmH2O-1 with the balloon method. No statistically significant difference was found between these two values. In conclusion, Cdyn, RL, and the P-V curve can be obtained precisely with the balloonless method.

scholarly journals Lung elastic recoil during breathing at increased lung volume

1999 ◽  
Vol 87 (4) ◽  
pp. 1491-1495 ◽  
Author(s):  
Joseph R. Rodarte ◽  
Gassan Noredin ◽  
Charles Miller ◽  
Vito Brusasco ◽  
Riccardo Pellegrino ◽  
...  
Keyword(s):  
Stress Relaxation ◽  
Tidal Volume ◽  
Lung Volume ◽  
Normal Subjects ◽  
Dynamic Hyperinflation ◽  
Airway Closure ◽  
Elastic Recoil ◽  
Volume Increase ◽  
Before And After ◽  
Residual Capacity

During dynamic hyperinflation with induced bronchoconstriction, there is a reduction in lung elastic recoil at constant lung volume (R. Pellegrino, O. Wilson, G. Jenouri, and J. R. Rodarte. J. Appl. Physiol. 81: 964–975, 1996). In the present study, lung elastic recoil at control end inspiration was measured in normal subjects in a volume displacement plethysmograph before and after voluntary increases in mean lung volume, which were achieved by one tidal volume increase in functional residual capacity (FRC) with constant tidal volume and by doubling tidal volume with constant FRC. Lung elastic recoil at control end inspiration was significantly decreased by ∼10% within four breaths of increasing FRC. When tidal volume was doubled, the decrease in computed lung recoil at control end inspiration was not significant. Because voluntary increases of lung volume should not produce airway closure, we conclude that stress relaxation was responsible for the decrease in lung recoil.

Changes in flow-volume curve configuration with bronchoconstriction and bronchodilation

1986 ◽  
Vol 61 (6) ◽  
pp. 2243-2251 ◽  
Author(s):  
C. R. O'Donnell ◽  
R. G. Castile ◽  
J. Mead
Keyword(s):  
Vital Capacity ◽  
Normal Subjects ◽  
Flow Volume ◽  
Slope Ratio ◽  
Lung Volumes ◽  
Volume Curve ◽  
Before And After ◽  
Lower Lung ◽  
Maximum Expiratory Flow ◽  
Flow Volume Curve

Changes in the configuration of maximum expiratory flow-volume (MEFV) curves following mild degrees of bronchodilation or bronchoconstriction were studied in five normal and five asthmatic subjects. In a volume-displacement plethysmograph, MEFV curves were performed before and after inhalation of aerosolized isoproterenol (I) or histamine (H). Five filtered MEFV curves were averaged, and slope ratio vs. volume (SR-V) plots were obtained from averaged curves. Following I, maximal flows at 75% of the vital capacity (VC) were decreased in asthmatics but not in normal subjects. Flows at 50 and 25% of the VC increased in normal subjects and asthmatics, whereas VC′s were unchanged. In asthmatics, sudden large decreases in flow (bumps) occurred at lower lung volumes following I. H reduced flows over the entire VC, with greater reductions occurring in asthmatics than in normals, particularly at low lung volumes. In asthmatics, VC was slightly reduced, and bumps in MEFV curve configuration occurred at higher lung volumes or were abolished entirely following H. A reduction in the amount of configurational detail appreciable in MEFV curves following histamine in asthmatics was best seen in SR-V plots. Following H, SR′s decreased regularly with decreasing lung volume in all the asthmatics but in none of the normals. This was the single most striking finding of this study. Mild I- and H-induced perturbations of airway bronchomotor tone produced small but consistent changes in MEFV curve configuration.(ABSTRACT TRUNCATED AT 250 WORDS)

Airway pressure-volume curve estimated by flow interruption during forced expiration

1989 ◽  
Vol 67 (6) ◽  
pp. 2631-2638 ◽  
Author(s):  
N. Ohya ◽  
J. Huang ◽  
T. Fukunaga ◽  
H. Toga
Keyword(s):  
Maximum Flow ◽  
Normal Subjects ◽  
Chronic Obstructive ◽  
Forced Expiration ◽  
Obstructive Pulmonary Disease ◽  
Volume Curve ◽  
Pressure Volume Curve ◽  
Mouth Pressure ◽  
Short Period ◽  
Volume Characteristics

We attempted to estimate the pressure-volume characteristics of airways downstream from the choke point when the airflow was abruptly interrupted during forced expiration. The change of gas volume of the downstream segment after interruption could be estimated by multiplying the maximum flow (Vmax) immediately before interruption by the interruption time because the Vmax is maintained for a short period after airflow interruption at the mouth, as described in our previous report (J. Appl. Physiol. 66: 509-517, 1989). For the pressure of the downstream segment, we used the mouth pressure itself. Airway compliance, a slope of the pressure-volume curve, was measured in an airway model in eight normal subjects, in six patients with chronic obstructive pulmonary disease (COPD), and in one patient with tracheobronchopathia osteochondroplastica. Airway compliance was 0.96 ml/cmH2O in normal subjects and 2.49 ml/cmH2O in COPD patients. This difference of airway compliance was believed to be caused by the longitudinal expansion of the downstream segment and changes in the properties of the airway wall.

Positive airway pressure and vertical transpulmonary pressure gradient in man

1975 ◽  
Vol 38 (5) ◽  
pp. 896-899 ◽  
Author(s):  
K. Rehder ◽  
N. Abboud ◽  
J. R. Rodarte ◽  
R. E. Hyatt
Keyword(s):  
Continuous Positive Airway Pressure ◽  
Pressure Gradient ◽  
Airway Pressure ◽  
Positive Airway Pressure ◽  
Transpulmonary Pressure ◽  
Vertical Gradient ◽  
Normal Subjects ◽  
Volume Curve ◽  
Pressure Volume Curve ◽  
Consistent Change

Static transpulmonary pressure (Pao-Pes) and the vertical gradient of transpulmonary pressure were determined in five sitting conscious normal subjects at mean airway pressures of 0 (ambient), 11, and 21 cmH2O. All subjects exhibited a nonuniform transpulmonary pressure gradient down the esophagus. The vertical pressure gradient was consistently larger in the lower (8–20cm below esophageal artifact) than in the middle region (0–8cm) of the esophagus. The gradient was not significantly altered by continuous positive airway pressure (11 and 21 cmH2O) or by changes in lung volume (60, 70, and 80% of total lung capacity (TLC)). Continuous positive airway pressure also did not result in a consistent change of the overall static pressure-volume curve of the lung. There was a small but statistically significant increase in TLC with each increase in airway pressure.

An analysis of pressure-volume characteristics of the lungs

1964 ◽  
Vol 19 (1) ◽  
pp. 97-104 ◽  
Author(s):  
Eduardo Salazar ◽  
John H. Knowles
Keyword(s):  
Transpulmonary Pressure ◽  
Normal Subjects ◽  
Mean Value ◽  
Inflation Pressure ◽  
Inspiratory Capacity ◽  
Volume Curve ◽  
Pressure Volume Curve ◽  
The Mean ◽  
Volume Characteristics ◽  
Pulmonary Volume

By analysis of the retractive forces of the lungs it was found that the pressure-volume characteristics of the lungs may be expressed by an exponential function. The curve described by such expression could be fitted to the experimental data obtained in 20 normal subjects. A half-inflation pressure (h) was defined which makes possible the evaluation of the retractive forces of the lungs by a measurement independent of lung size and accounting for known curvilinearity. H is a useful index of the stiffness of the organ and it is defined as the increase in transpulmonary pressure necessary to inflate the lungs halfway to the maximal pulmonary volume from any resting level. The mean value of h for the group was 7.58 ± 2.53 cm H2O. The half-inflation pressure is independent of the level of measurement within the inspiratory capacity and it does not vary with or depend on the size of the lungs. It may therefore be a more useful expression of the retractive forces of the lungs than compliance. pulmonary retractive forces; lung stiffness; compliance half-inflation pressure and lung size; VC and half-inflation pressure; FRC and half-inflation pressure; new expression for compliance; pressure-volume curve Submitted on March 4, 1963

scholarly journals Response to Recruitment Maneuver Influences Net Alveolar Fluid Clearance in Acute Respiratory Distress Syndrome

2007 ◽  
Vol 106 (5) ◽  
pp. 944-951 ◽  
Author(s):  
Jean-Michel Constantin ◽  
Sophie Cayot-Constantin ◽  
Laurence Roszyk ◽  
Emmanuel Futier ◽  
Vincent Sapin ◽  
...  
Keyword(s):  
Acute Respiratory Distress Syndrome ◽  
Respiratory Distress Syndrome ◽  
Respiratory Distress ◽  
Distress Syndrome ◽  
Recruitment Maneuver ◽  
Alveolar Recruitment ◽  
Alveolar Fluid Clearance ◽  
Volume Curve ◽  
Pressure Volume Curve ◽  
Before And After

Background Alveolar fluid clearance is impaired in the majority of patients with acute respiratory distress syndrome (ARDS). Experimental studies have shown that a reduction of tidal volume increases alveolar fluid clearance. This study was aimed at assessing the impact of the response to a recruitment maneuver (RM) on net alveolar fluid clearance. Methods In 15 patients with ARDS, pulmonary edema fluid and plasma protein concentrations were measured before and after an RM, consisting of a positive end-expiratory pressure maintained 10 cm H2O above the lower inflection point of the pressure-volume curve during 15 min. Cardiorespiratory parameters were measured at baseline (before RM) and 1 and 4 h later. RM-induced lung recruitment was measured using the pressure-volume curve method. Net alveolar fluid clearance was measured by measuring changes in bronchoalveolar protein concentrations before and after RM. Results In responders, defined as patients showing an RM-induced increase in arterial oxygen tension of 20% of baseline value or greater, net alveolar fluid clearance (19 +/- 13%/h) and significant alveolar recruitment (113 +/- 101 ml) were observed. In nonresponders, neither net alveolar fluid clearance (-24 +/- 11%/h) nor alveolar recruitment was measured. Responders and nonresponders differed only in terms of lung morphology: Responders had a diffuse loss of aeration, whereas nonresponders had a focal loss of aeration, predominating in the lower lobes. Conclusion In the absence of alveolar recruitment and improvement in arterial oxygenation, RM decreases the rate of alveolar fluid clearance, suggesting that lung overinflation may be associated with epithelial dysfunction.

Dynamic respiratory mechanics in intact anesthetized hamsters

1980 ◽  
Vol 49 (2) ◽  
pp. 197-203 ◽  
Author(s):  
G. L. Strope ◽  
C. L. Cox ◽  
R. L. Pimmel ◽  
W. A. Clyde
Keyword(s):  
Tidal Volume ◽  
Respiratory Mechanics ◽  
Minute Ventilation ◽  
Dynamic Compliance ◽  
Respiratory Frequency ◽  
Small Animals ◽  
Mean Values ◽  
Expiratory Resistance ◽  
Inspiratory Resistance ◽  
Acute Changes

A system for measuring parameters of ventilation and respiratory mechanics in intact anesthetized hamsters was developed. Means ± SD of five weekly measurements in eight hamsters were 0.68 ± 0.09 ml for tidal volume, 45 ± 14 breaths.min-1 for respiratory frequency, 29.3 ± 10.4 ml.min-1 for minute ventilation, 0.301 ± 0.080 ml.cmH2O-1 for dynamic compliance, 0.435 ± 0.151 cmH2O.ml-1.s for inspiratory resistance, 0.311± 0.101 cmH2O.ml-1.s for expiratory resistance, and 0.334 ± 0.096 cmH2O.ml-1.s for average resistance. The standard deviations of five consecutive measurements of these parameters on the same day were typically 10% of the corresponding mean values suggesting that acute changes as small as 10% can be detected in a study of similar size. The corresponding value for five single measurements on different days at weekly intervals was 30%. We believe that this system yields reasonable and repeatable measurements, and, because it is atraumatic, it can be used in chronic studies of diseases in hamsters and other small animals.

Positive- and negative-pressure breathing in newborn rat before and after anesthesia

1984 ◽  
Vol 57 (5) ◽  
pp. 1454-1461 ◽  
Author(s):  
D. Marlot ◽  
J. P. Mortola
Keyword(s):  
Breathing Pattern ◽  
Minute Ventilation ◽  
Respiratory Pattern ◽  
Flow Profile ◽  
Newborn Rat ◽  
Volume Curve ◽  
Pressure Volume Curve ◽  
Before And After ◽  
Residual Capacity ◽  
Expiratory Flow

We have examined the effects of changes in functional residual capacity (FRC), determined by positive and negative body surface pressures, on the breathing pattern of intact newborn rats, before and after barbiturate anesthesia. With distending pressures (between 1 and 4 cmH2O) minute ventilation decreased mainly due to a prolongation of the expiratory time. This response was more marked after anesthesia and accompanied by a fall in tidal volume. The time of peak expiratory flow (TE'), an index of expiratory flow resistance, was not changed before anesthesia and only slightly decreased after anesthesia. With collapsing pressures between 1 and 2 cmH2O only small changes in breathing pattern occurred, whereas the TE' increased in all cases and the flow profile indicated a maintenance of lung volume during expiration. These data indicate that tonic vagal information is present in the newborn rat and is substantially enhanced after barbiturates. The result that changes in breathing pattern are not fully matched by the changes in TE' and expiratory flow profile may indicate that the receptors which control the respiratory pattern are not the same as those involved in the regulation of the expiratory flow. The pressure-volume curve of the respiratory system was similar before and after anesthesia, and the intercept was close to the zero pressure value, indicating that the FRC of the newborn rat, differently from the human baby, is not actively maintained above the resting volume of the system.

Effect of lidocaine on left ventricular pressure-volume curves during demand ischemia in pigs

1998 ◽  
Vol 274 (6) ◽  
pp. H2100-H2109 ◽  
Author(s):  
Masao Tayama ◽  
Steven B. Solomon ◽  
Stanton A. Glantz
Keyword(s):  
Diastolic Dysfunction ◽  
Diastolic Pressure ◽  
Systolic Function ◽  
Left Ventricular ◽  
Volume Curve ◽  
Pressure Volume Curve ◽  
Volume Relationship ◽  
Before And After ◽  
Lidocaine Injection ◽  
Pressure Volume Relationship

The diastolic pressure-volume curve shifts upward during demand ischemia, most likely because of changes in Ca2+ dynamics within the sarcomere. It is possible that agents that affect Na+/Ca2+exchange, such as lidocaine, a class 1b-type Na+-channel blocker that decreases intracellular Na+, could affect the diastolic pressure-volume relationship because of indirect effects on intracellular Ca2+. Lidocaine is a drug widely used to treat arrhythmias in patients with myocardial ischemia. We studied the effects of lidocaine on diastolic dysfunction associated with demand ischemia. We compared diastolic (as represented by the shift in the diastolic pressure-volume relationship) and systolic function during demand ischemia before and after lidocaine injection. We created demand ischemia in pigs before and after administering lidocaine (5 mg/kg) in eight open-pericardium anesthetized pigs. Demand ischemia was induced by constricting the left anterior descending coronary artery and then pacing at 1.5–1.8 times the baseline heart rate for 1.5–3 min. Hemodynamics were recorded during baseline, demand ischemia, baseline after lidocaine injection, and demand ischemia after lidocaine. Lidocaine did not affect systolic function or the time constant of isovolumic relaxation, but it increased the upward shift of the diastolic pressure-volume curve during demand ischemia compared with the increase that occurred before lidocaine was administered. This result suggests that lidocaine could aggravate diastolic dysfunction in patients with ischemic heart disease.

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