spirometer

In clinical practice and research, any device used for measuring flows and volumes, inspired and expired by the lungs, thus assessing pulmonary function. Considered the most basic measurement device of pulmonary function. [L. spiro, to breathe, + G. metron, measure]

- chain-compensated s. a Tissot s. in which compensation for change in bell buoyancy is accomplished automatically by a suspending chain of correct mass per unit length.

- Krogh s. a water-sealed s. in which the bell is a large, shallow, rectangular box rotating slightly around a horizontal axis extending along one edge, with an arm extending beyond that axis to a counterbalancing weight; comparable with a wedge s..

- Tissot s. a very large water-sealed s. designed for accumulating expired gas over a long period of time; the counterbalancing of the bell (almost frictionless) is compensated for by the bell's change in buoyancy as it emerges from the water, keeping the contained gas precisely at ambient atmospheric pressure.

- wedge s. a waterless s. constructed of two large rectangular plates with edges connected by accordion-pleated rubber so that large changes in volume are accommodated by small changes in the acute angle of the wedge-shaped interior, sensed by an electrical transducer; designed for rapid response by reducing the acceleration of the moving parts.

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spi·rom·e·ter spi-'räm-ət-ər n an instrument for measuring the air entering and leaving the lungs

spi·ro·met·ric .spī-rə-'me-trik adj

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n.

an instrument for measuring the volume of air inhaled and exhaled. It is used in tests of ventilation.

• spirometry n.

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spi·rom·e·ter (spi-romґə-tər) [spiro-² + -meter] an instrument for measuring the air inhaled into and exhaled from the lungs, such as in pulmonary function tests.