Functional residual capacity

Fibroelastic Fibrous material possessing elastic properties. In the airway, fi-broelastic tissue throughout the lung contributes to its overall elasticity, generating a positive recoil force at the functional residual capacity, or resting state of the lungs. 

Functional residual capacity (FRC) Gas volume remaining in the airway at... 

Define functional residual capacity, inspiratory capacity, total lung capacity, and vital capacity... 

Both the Weibel A and Yeh-Schum models need to be reduced in scale to represent adult human lung at a normal level of inflation corresponding to 3000 ml functional residual capacity (FRC) (Yu and Diu, 1982). Partial scaling has been included in some dosimetric models (NEA, 1983 James, 1984) but not in others. In all cases the airway sizes used to represent adult lung correspond to a higher level of inflation than the standard FRC, leading to general but relatively small underestimates of bronchial dose. 

Most lung volumes can be measured with a spirometer except total lung capacity (TLC), functional residual capacity (FRC) and residual volume (RV). The FRC can be measured by helium dilution or body plethysmography. 

After 2 h of ozone exposure, there was a significant change (p < 0.05) in Fvc, KMF, and airway resistance (Raw) Several other measures (feVi, Vjq, and V35) were lower after 2 h of exposure, but the statistical significance was borderline. However, after 4 h of exposure, all flow measures were significantly decreased, compared with controls. After 4 h, increased, FVC decreased further, and feV decreased significantly. Residual volume, functional residual capacity, and total lung volume did not change as a result of the ozone exposure. 

Du Bois. A. B., S. Y. Botelho, G. N. Bedell. R. Marshall, and J. H. Comroe. A rapid plethysmographic method for measuring thoracic gas volume A comparison with a nitrogen washout method for measuring functional residual capacity in normal subjects. J. Clin. Invest. 35 322-326, 1956. 

Total lung capacity Inspiratory capacity Functional residual capacity... 

Male Wistar rats exposed to 243 ppm [437 mg/m ] acetaldehyde atmospheres for 8 h per day on five days per week for five weeks showed increases in functional residual capacity, residual volume, total lung capacity and respiratoiy frequency. These changes were interpreted as being caused by damage to the peripheral regions of the lung parenchyma (Saldiva et al., 1985). 

Alveolar wash-in This term refers to the replacement of the normal lung gases with the inspired anesthetic mixture. The time required for this process is directly proportional to the functional residual capacity of the lung, and inversely proportional to the ventilatory rate it is independent of the physical properties of the gas. Once the partial pressure builds within the lung, anesthetic uptake from the lung begins. 

C asthmatic (5 men and S wmen, aged 18-25) 0 0,0.8, or 1.8 45 min (15 min exercise, 15 min nest, 15 min exercise) No treatment related effects, including increase in severity of upper respiratory lower respiratory, other symptoms no significant differences between treated and control groups in pulmonary function tests (total respiratory resistance, thoracic gas volume at functional residual capacity, forced expiratory volume, forced viral capacity, maximal flow at 50% and 75% of expired vital capacity) no changes in nasal power data between treated and control groups Stevens et al. 1992... 

For MDIs, lung deposition can be enhanced by (1) gentle exhalation to residual volume rather than to functional residual capacity, (2) slow inhalation (lOL/min) rather that fast inhalation (50L/min), and (3) breath hold of 10 sec rather than none at end of puff inhalation. These observations were based on measurement of urinary albuterol at 30-min postinhalation, which is considered to reflect lung delivery and to avoid gastrointestinal (GI) tract deposition [36], The effect of inhalation flowrate through an aerosol device can greatly affect particle size, a factor that may explain in part the reduced deposition with suboptimal flowrates. Failure to quickly achieve optimal inspiratory flowrate via a budesonide Turbuhaler can result in an increase in size from <6.6 microns to... 

Respiratory function tests should be conducted before exposure and, at least, after the final exposure and at the end of a recovery period. Components that may be studied include compliance, total lung capacity, functional residual capacity, forced vital capacity, resistance, and CO diffusing capacity (Harkema et al., 1982 Sun et al., 1987). 

The functional residual capacity (FRC) is the volume of air remaining in the lungs at the end of a quiet expiration. FRC is the normal resting position of the lung and occurs when there is no contraction of either inspiratory or expiratory muscles and is normally 40% of TLC. Inspiratory capacity (IC) is the maximal volume of air that can be inhaled from the end of a quiet expiration and represents the sum ofVT and IRV. 

FIGURE 25-1. Lung volumes and capacities. ERV = expiratory reserve volume FRC = functional residual capacity IC = inspiratory capacity IRV = inspiratory reserve volume RV = residual volume TLC = total lung capacity VC = vital capacity Vj = tidal volume. 

FRC Functional residual capacity the volume of air remaining in the lung after normal expiration. 

Lung Emphysematous changes pulmonary infarcts reduced bacterial clearance muscle atrophy Pneumonia decreases in functional residual capacity, vital capacity, and maximum breathing capacity depressed hypoxic/hypercarbic drives... 

All the static lung volumes and capaeities except FRC and RV can be measured directly through use of a simple spirometer (an apparatus traditionally consisting of a cylindrical bell immersed in water and equipped with outlets that a person can breathe into, or inhale from, to measure expiratory or inspiratory volumes). Functional residual capacity and RV are measured indirectly by using several alveolar gas dilution techniques. 

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