Forced Expiratory Volume: From 1 Different Sources
(FEV) the volume of air exhaled in a given period (usually limited to 1 second in tests of vital capacity). FEV is reduced in patients with obstructive airways disease and diminished lung volume.
That fraction of the blood’s total volume made up of red cells. The packed cell volume is found by centrifuging blood in a tube and measuring the depth of the column of red cells as a fraction of the whole column of blood. (See also HAEMATOCRIT.)... packed cell volume
The additional amount of air that a person could breathe in or out if he or she were not using the full capacity of their LUNGS. (See also LUNG VOLUMES.)... reserve volume
The amount of air left in the LUNGS after an individual has breathed out as much as possible. It is a measure of lung function: for example, in a person with EMPHYSEMA the residual volume is increased. (See RESPIRATION; LUNG VOLUMES.)... residual volume
A means of encouraging EXCRETION via the KIDNEYS of a compound by altering the pH and increasing the volume of the urine. Forced diuresis is occasionally used after drug overdoses, but is potentially dangerous and so only suitable where proper intensive monitoring of the patient is possible. Excretion of acid compounds, such as salicylates, can be encouraged by raising the pH of the urine to 7·5–8·5 by the administration of an alkali such as bicarbonate (forced alkali diuresis) and that of bases, such as AMPHETAMINES, by lowering the pH of the urine to 5·5–6·5 by giving an acid such as ammonium chloride (forced acid diuresis).... forced diuresis
See ENTERAL FEEDING.... forced feeding
(FPL test) a test used to evaluate the *visual acuity of infants and young children by observing whether the child looks at a blank screen or one with stripes, the spatial frequency of which can be changed.... forced preferential looking test
an apparent decrease in the visibility of a structure in a *cross-sectional imaging technique, such as CT or MRI, when either the thickness of the object is much less than that of the slice being used to make the image, or the object is only partially imaged within the slice. See artifact.... partial volume artifact
(PEFR) the maximum rate at which a person can forcibly expel air from the lungs at any time, expressed usually in litres per minute (occasionally in litres per second). A low value can help diagnose asthma in the correct clinical context, and differences between the morning and evening values can also be a feature of poor control of asthma. There is a place for PEFR in the monitoring of acute exacerbations of chronic pulmonary obstructive disease (COPD) but not in the diagnosis of COPD.... peak expiratory flow rate
the amount of blood ejected from each ventricle on each contraction, which can be affected by medication, exercise, decreases in the volume of circulating blood, or heart anomalies. In a healthy adult, stroke volume is estimated at 70 ml.... stroke volume
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