Density dependence of forced expiratory flows in healthy infants and toddlers

1999 ◽  
Vol 87 (5) ◽  
pp. 1796-1801 ◽  
Author(s):  
Stephanie Davis ◽  
Marcus Jones ◽  
Jeff Kisling ◽  
Robert Castile ◽  
Robert S. Tepper
Keyword(s):  
Density Dependence ◽  
Peripheral Resistance ◽  
Older Children ◽  
Significant Relationships ◽  
Volume Curve ◽  
Healthy Infants ◽  
Flow Volume Curve ◽  
Forced Expiratory Flow ◽  
The Mean ◽  
Expiratory Flow

In older children and adults, density dependence (DD) of forced expiratory flow is present over the majority of the full flow-volume curve. In healthy subjects, DD occurs because the pressure drop from peripheral to central airways is primarily dependent on turbulence and convective acceleration rather than laminar resistance; however, an increase in peripheral resistance reduces DD. We measured DD of forced expiratory flow in 22 healthy infants to evaluate whether infants have low DD. Full forced expiratory maneuvers were obtained while the subjects breathed room air and then a mixture of 80% helium-20% oxygen. Flows at 50 and 75% of expired forced vital capacity (FVC) were measured, and the ratio of helium-oxygen to air flow was calculated (DD at 50 and 75% FVC). The mean (range) of DD at 50 and 75% FVC was 1.37 (1.22–1.54) and 1.23 (1.02–1.65), respectively, values similar to those reported in older children and adults. There were no significant relationships between DD and age. Our results suggest that infants, compared with older children and adults, have similar DD, a finding that suggests that infants do not have a greater ratio of peripheral-to-central airway resistance.

Density dependence of maximal expiratory flow before and during tracheal constriction in dogs

1986 ◽  
Vol 60 (3) ◽  
pp. 1060-1066 ◽  
Author(s):  
R. G. Castile ◽  
O. F. Pedersen ◽  
J. M. Drazen ◽  
R. H. Ingram
Keyword(s):  
Density Dependence ◽  
Lung Volumes ◽  
Maximal Expiratory Flow ◽  
Volume Curve ◽  
Before And After ◽  
Lower Lung ◽  
Flow Volume Curve ◽  
Expiratory Flow ◽  
Longitudinal Extension ◽  
Central Airway

The effect of carbachol-induced central bronchoconstriction on density dependence of maximal expiratory flow (MEF) was assessed in five dogs. MEFs were measured on air and an 80% He-20% O2 mixture before and after local application of carbachol to the trachea. Airway pressures were measured using a pitot-static probe, from which central airway areas were estimated. At lower concentrations of carbachol the flow-limiting site remained in the trachea over most of the vital capacity (VC), and tracheal area and compliance decreased in all five dogs. In four dogs, decreases in choke point area predominated and produced decreases in flows. In one dog the increase in airway “stiffness” apparently offset the fall in area to account for an increase in MEF. Density dependence measured as the ratio of MEF on HeO2 to MEF on air at 50% of VC increased in all five dogs. Increases in density dependence appeared to be related to increases in airway stiffness at the choke point rather than decreases in gas-related airway pressure differences. Lower concentrations produced a localized decrease in tracheal area and extended the plateau of the flow-volume curve to lower lung volumes. Higher concentrations caused further reductions in tracheal area and greater longitudinal extension of bronchoconstriction, resulting in upstream movement of the site of flow limitation at higher lung volumes. Density dependence increased if the flow-limiting sites remained in the trachea at mid-VC but fell if the flow-limiting site had moved upstream by that volume.

Detection of heterogeneous lung emptying by shape of forced expiratory flow-volume curve in asthmatic children

2018 ◽  
Author(s):  
David Richard ◽  
Sabrina Khelil ◽  
Stéphanie Metche ◽  
Aurelie Tatopoulos ◽  
Sébastien Kiefer ◽  
...  
Keyword(s):  
Flow Volume ◽  
Asthmatic Children ◽  
Volume Curve ◽  
Flow Volume Curve ◽  
Forced Expiratory Flow ◽  
Expiratory Flow

scholarly journals Assessing small airway disease in GLI versus NHANES III based spirometry using area under the expiratory flow-volume curve

2019 ◽  
Vol 6 (1) ◽  
pp. e000511 ◽  
Author(s):  
Octavian C Ioachimescu ◽  
James K Stoller
Keyword(s):  
Airway Disease ◽  
Nhanes Iii ◽  
Flow Volume ◽  
Predictive Equations ◽  
Small Airway Disease ◽  
Volume Curve ◽  
Flow Volume Curve ◽  
Forced Expiratory Flow ◽  
Expiratory Flow ◽  
Diagnostic Concordance

BackgroundSpirometry interpretation is influenced by the predictive equations defining lower limit of normal (LLN), while ‘distal’ expiratory flows such as forced expiratory flow at 50% FVC (FEF50) are important functional parameters for diagnosing small airway disease (SAD). Area under expiratory flow-volume curve (AEX) or its approximations have been proposed as supplemental spirometric assessment tools. We compare here the performance of AEX in differentiating between normal, obstruction, restriction, mixed defects and SAD, as defined by Global Lung Initiative (GLI) or National Health and Nutrition Examination Survey (NHANES) III reference values, and using various predictive equations for FEF50.MethodsWe analysed 15 308 spirometry-lung volume tests. Using GLI versus NHANES III LLNs, and diagnosing SAD by the eight most common equation sets for forced expiratory flow at 50% of vital capacity lower limits of normal (FEF50 LLN), we assessed the degree of diagnostic concordance and the ability of AEX to differentiate between various definition-dependent patterns.ResultsConcordance rates between NHANES III and GLI-based classifications were 93.7%, 78.6%, 86.8%, 88.0%, 93.8% and 98.8% in those without, with mild, moderate, moderately severe, severe and very severe obstruction, respectively (agreement coefficient 0.81 (0.80–0.82)). The prevalence of SAD was 0.6%–6.9% of the cohort, depending on the definition used. The AEX differentiated well between normal, obstruction, restriction, mixed pattern and SAD, as defined by most equations.ConclusionsIf the SAD diagnosis is established by using mean FEF50 LLN or a set number of predictive equations, AEX is able to differentiate well between various spirometric patterns. Using the most common predictive equations (NHANES III and GLI), the diagnostic concordance for functional type and obstruction severity is high.

scholarly journals Raised-Volume Forced Expiratory Flow-Volume Curve in Healthy Taiwanese Infants

2017 ◽  
Vol 7 (1) ◽  
Author(s):  
Shen-Hao Lai ◽  
Sui-Ling Liao ◽  
Tsung-Chieh Yao ◽  
Ming-Han Tsai ◽  
Man-Chin Hua ◽  
...  
Keyword(s):  
Flow Volume ◽  
Volume Curve ◽  
Flow Volume Curve ◽  
Forced Expiratory Flow ◽  
Expiratory Flow

Dynamic mechanisms determine functional residual capacity in mice, Mus musculus

1979 ◽  
Vol 46 (5) ◽  
pp. 867-871 ◽  
Author(s):  
A. Vinegar ◽  
E. E. Sinnett ◽  
D. E. Leith
Keyword(s):  
Tidal Volume ◽  
Functional Residual Capacity ◽  
Flow Volume ◽  
Linear Portion ◽  
Volume Curve ◽  
Flow Volume Curve ◽  
Residual Capacity ◽  
Expiratory Flow ◽  
The Difference ◽  
Pentobarbital Sodium Anesthesia

Awake mice (22.6--32.6 g) were anesthetized intravenously during head-out body plethysmography. One minute after pentobarbital sodium anesthesia, tidal volume had fallen from 0.28 +/- 0.04 to 0.14 +/- 0.02 ml and frequency from 181 +/- 20 to 142 +/- 8. Functional residual capacity (FRC) decreased by 0.10 +/- 0.02 ml. Expiratory flow-volume curves were linear, highly repeatable, and submaximal over substantial portions of expiration in awake and anesthetized mice; and expiration was interrupted at substantial flows that abruptly fell to and crossed zero as inspiration interrupted relaxed expiration. FRC is maintained at a higher level in awake mice due to a higher tidal volume and frequency coupled with expiratory braking (persistent inspiratory muscle activity or increased glottal resistance). In anesthetized mice, the absence of braking, coupled with reductions in tidal volume and frequency and a prolonged expiratory period, leads to FRCs that approach relaxation volume (Vr). An equation in derived to express the difference between FRC and Vr in terms of the portion of tidal volume expired without braking, the slope of the linear portion of the expiratory flow-volume curve expressed as V/V, the time fraction of one respiratory cycle spent in unbraked expiration, and respiratory frequency.

scholarly journals Relationship Between Spontaneous Expiratory Flow-Volume Curve Pattern and Air-Flow Obstruction in Elderly COPD Patients

2013 ◽  
Vol 58 (10) ◽  
pp. 1643-1648 ◽  
Author(s):  
M. Nozoe ◽  
K. Mase ◽  
S. Murakami ◽  
M. Okada ◽  
T. Ogino ◽  
...  
Keyword(s):  
Air Flow ◽  
Flow Volume ◽  
Curve Pattern ◽  
Volume Curve ◽  
Copd Patients ◽  
Flow Volume Curve ◽  
Expiratory Flow
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