Lung volumes functional residual capacity

Brown, L.K., and Miller, A., Full lung volumes functional residual capacity, residual volume, and total lung capacity. In Pulmonary Function Tests A Guide for the Student and House Officer (Miller, A. ed.). New York Grune Stratton, Inc., 1987, pp. 53-58. 

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. 

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. 

Deposition in the thoracic region is the sum of aerodynamic and thermodynamic deposition of particulate material. Aerodynamic deposition depends on aerodynamic particle size, total volumetric flow rate, anatomical dead space, tidal volume, functional residual capacity (FRC) (combined residual and expiratory reserve volume or the amount of air remaining in the lungs after a tidal expiration) and diameter of the airways. Thermodynamic deposition depends on anatomical and physical characteristics, such as tidal volume, anatomical dead space, functional residual capacity and the transit time of air within each region. Thermodynamic particle size, which is derived from the diffusion coefficient, particle shape factor and the particles mass density, influence thermodynamic deposition. 

Stocks J, Quanjer PH. Reference values for residual volume, functional residual capacity and total lung capacity. ATS Workshop on Lung Volume Measurements. Official statement of the European Respiratory Society. Eur Respir J 1995 492-506. 

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. 

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). 

Functional residual capacity (FRC) Volume of gas remaining in lungs at end of tidal expiration... 

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... 

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. 

Functional residual capacity (FRC) The volume of gas in the lungs at the end of a normal expiration. 

Specific compliance, which is defined as compliance divided by functional residual capacity (FRC, or the resting volume of the lung), appears to assume a nearly constant value of 0.00082 m /N (0.08/cm H2O) for the whole size spectrum of mammals from bats to whales (Mines, 1981). 

Functional residual capacity The lung volume at rest without breathing. 

The functional residual capacity (FRC) and the residual volume (RV) are the only lung compartments that cannot be measured with a volume-measuring device. Measuring these requires use of the nitrogen analyzer and application of the dilution method. 

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