Total lung capacity measurement

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. 

This is a test to assess the degree of airway limitation. It is easy to perform and relatively inexpensive. The patient takes a full inspiration to total lung capacity and then blows out forcefully into the peak flow meter. The best of three recordings are normally taken. The peak flow measures the expiratory flow rate in the first 2 ms of expiration and can overestimate the extent of lung function in patients with moderate to severe airway limitation. Other tests such as... 

The approach most commonly used to evaluate effects on distal airways in clinical and occupational medicine is the maximum forced expiratory maneuver, which allows measurement of airflows as a function of lung volume from total lung capacity to residual volume. Typically, the forced vital capacity (FVC) and the forced expiratory volume at 1 s (as a % of FVC) (FEVi) are measured. Peak expiratory flow is a frequently used measure since simple portable devices permit self-evaluation by patients with obstructive disease. Decreased airflow rates are seen with emphysema, chronic bronchitis, and following... 

Peak flow measurements. Perhaps the simplest measurement of expiratory airflow involves the use of a peak flowmeter. Subjects inspire maximally (i.e., to total lung capacity) and expire rapidly and maximally to residual volume into the mouthpiece of the instrument that provides a measurement of the peak expiratory flow. These instruments are simple to operate and often are provided to asthmatic patients for self-measurement and documentation of their ventilatory function. 

The combinations or sums of two or more lung volumes are termed capacities (see Fig. 25-1). Vital capacity (VC) is the maximal amount of air that can be exhaled after a maximal inspiration. It is equal to the sum of the IRV, Vt, and ERV. When measured on a forced expiration, it is called the forced vital capacity (FVC). When measured over an exhalation of at least 30 seconds, it is called the slow vital capacity (SVC, VC). The VC is approximately 75% of the total lung capacity (TLC), and when the SVC is within the normal range, a significant restrictive disorder is unlikely. Normally, the values for SVC and FVC are very similar unless airway obstruction is present. 

Examination of lung volumes often indicate that total lung capacity is normal but that there is a moderate elevation of residual volume and hence a mild decrease in vital capacity. Compliance and carbon monoxide difiiision capacity (DlCO) measurements are usually normal. 

FIGURE 7.4.14 Lung function measurements related to body height and age in males. TLC, total lung capacity VC, vital capacity, RV, residnal volume. (From Bartlett, R.G., Respiratory system, in Bioastronautics Data Book, J.F. Parker, Jr. and V.R. West, eds., NASA, Washington, EXT, 1973,489-531.)... 

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. 

Divisions of the Total Lung Capacity 102 Workers with Small Lungs 102 Measurement of the Transfer Factor (DLCO) and Transfer Coefficient (KCO) 103 Workers with Large Lungs 105 Measures of Forced Expiration and Inspiration 106 Asthma 109... 

After a full expiration, there is air left within the lungs this is the residual volume and cannot be measured directly. It is calculated by measuring the total lung capacity and subtracting the vital capacity. The vital capacity (or forced vital capacity if the subject is asked to breathe out as hard and fast as possible) is measured directly by asking the subject to inhale until no more air can be inhaled and then breathe out until flow ceases. 

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. 

Hardware, the acquisition sub-system, is divided into body shape test unit, physical test unit, as well as a total of 11 instruments (height measuring apparatus, weight measuring apparatus, lung capacity scanner. 

By the measurement of lung and forced expiratory volumes, nasal, lower and total airway resistances, closing volume data, the phase III slope of the alveolar plateau, and the maximum expiratory ow volume, peripheral airway dysfunction was con rmed in 24 adults with common colds. In a randomized, controlled trial, an aromatic mixture of menthol, eucalyptus oil, and camphor (56%, 9%, and 35% w/w, respectively) were vaporized in a room where the subjects were seated. Respiratory function measurements were made at baseline, 20 and 60 min after exposure. After the last measurement, phenylephrine was sprayed into the nostrils and the measurements taken again 5-10 min later to determine potential airway responsiveness. The control consisted of tap water. The results showed sign cant changes in forced vital capacity, forced expiratory volume, closing capacity, and the phase III slope after aromatic therapy as compared to the control. It was con eluded that the aromatic inhalation favorably modi ed the peripheral airway dysfunction (Cohen and Dressier, 1982). 

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