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Spirometer

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Spirometer

A spirometer is an apparatus for measuring the volume of air inspired and expired by the lungs. A spirometer measures ventilation, the movement of air into and out of the lungs. The spirogram will identify two different types of abnormal ventilation patterns, obstructive and restrictive. There are various types of spirometers which use a number of different methods for measurement (pressure transducers, ultrasonic, water gauge).

Contents

Pulmonary function tests

A spirometer is the main piece of equipment used for basic Pulmonary Function Tests (PFTs). Lung diseases such as asthma, bronchitis, and emphysema can be ruled out from the tests. In addition, a spirometer is often used for finding the cause of shortness of breath, assessing the effect of contaminants on lung function, the effect of medication, and evaluating progress for disease treatment.

Reasons for testing

  • Diagnose certain types of lung disease (such as asthma, bronchitis, and emphysema)
  • Find the cause of shortness of breath
  • Measure whether exposure to chemicals at work affects lung function
  • Check lung function before someone has surgery
  • Assess the effect of medication
  • Measure progress in disease treatment
  • Early development

    The earliest attempt to measure lung volume can be dated back to the period A.D. 129-200. Claudius Galen, a Roman doctor and philosopher, did a volumetric experiment on human ventilation. He had a boy breathe in and out of a bladder and found that the volume did not change. The experiment proved inconclusive.

  • 1681, Borelli tried to measure the volume of air inspired in one breath. He assembled a cylindrical tube partially filled with water, with an open water source entering the bottom of the cylinder. He occluded his nostrils, inhaled through an outlet at the top of the cylinder and measured the volume of air displaced by water. This technique is very important in getting parameters of lung volume nowadays.
  • Nineteenth century

  • 1813, Kentish E used a simple "Pulmometer" to study the effect of diseases on pulmonary lung volume. He used an inverted graduated bell jar standing in water, with an outlet at the top of the bell jar controlled by a tap. The volume of air was measured in units of pints.
  • 1831, Thrackrah C.T described a "Pulmometer" similar to that of Kentish. He portrayed the device as a bell jar with an opening for the air to enter from below. There was no correction for pressure. Therefore, the spirometer not only measured the respiratory volume, but also the strength of the respiratory muscles.
  • 1845, Vierordt in his book named "Physiologie des Athmens mit besonderer Rücksicht auf die Auscheidung der Kohlensäure" discussed his interest in measuring the volume of expiration accurately. He also completed accurate measures of other volume parameters by using his "Expirator". Some of the parameters described by him are used today, including residual volume and vital capacity.
  • 1846 The water spirometer measuring vital capacity was developed by a surgeon named John Hutchinson. He invented a calibrated bell inverted in water, which was used to capture the volume of air exhaled by a person. Hutchinson published his paper about his water spirometer and the measurements he had taken from over 4,000 subjects, describing the direct relationship between vital capacity and height and the inverse relationship between vital capacity and age. He also showed that vital capacity does not relate to weight at any given height. He also used his machine for the prediction of premature mortality. He coined the term 'vital capacity', which was claimed as a powerful prognosis for heart disease by the Framingham study. He believed that his machine should be used for actuarial predictions for companies selling life insurance.
  • 1854 Wintrich developed a spirometer, which was easier to use than Hutchinson's. He did an experiment with 4,000 subjects and concluded that there are three parameters affecting vital capacity: height, weight and age. His experiment produced results similar to those of Hutchinson's study.
  • 1859 E. Smith developed a portable spirometer, which he used to measure gas metabolism.
  • 1866 Salter added a kymograph to the spirometer in order to record time while obtaining air volumes.
  • 1879 Gad J. published a paper entitled "Pneumatograph" which described a machine that allowed the recording of lung volume changes.
  • Twentieth century

  • 1902, Brodie T.G was the first to use a dry-bellowed wedge spirometer.
  • 1904 Tissot introduced the closed-circuit spirometer
  • 1939 Compton S.D. developed the lungometer for use by Nazi Germany.
  • 1959 Wright B.M. and McKerrow C.B. introduced the peak flow meter.
  • 1969 DuBois A.B. and van de Woestijne K.P. experimented on humans using the whole body plethysmograph. *1974 Campbell et al. refined the previous peak flow meter, devoloping a cheaper and lighter version.
  • Twenty-first century

  • 2008 Advanced Medical Engineering developed the world's first wireless spirometer with 3D Tilt-Sensing for far greater quality control in the testing environment.
  • Whole body plethysmograph

    This type of spirometer gives a more accurate measurement for the components of lung volumes as compared to other conventional spirometers. A person is enclosed in a small space when the measurement is taken.

    Pneumotachometer

    This spirometer measures the flow rate of gases by detecting pressure differences across fine mesh. One advantage of this spirometer is that the subject can breathe fresh air during the experiment.

    Fully electronic spirometer

    Electronic spirometers have been developed that compute airflow rates in a channel without the need for fine meshes or moving parts. They operate by measuring the speed of the airflow with techniques such as ultrasonic transducers, or by measuring pressure difference in the channel. These spirometers have greater accuracy by eliminating the momentum and resistance errors associated with moving parts such as windmills or flow valves for flow measurement. They also allow improved hygiene by allowing fully disposable air flow channels.

    Incentive spirometer

    This spirometer is specially designed to improve one's lung function.

    Peak flow meter

    This device is useful for measuring how well a person's lungs expel air.

    Windmill-type spirometer

    This type of spirometer is used especially for measuring forced vital capacity without using water; it has broad measurements ranging from 1000 ml to 7000 ml. It is more portable and lighter than traditional water-tank type spirometers. This spirometer should be held horizontally while taking measurements because of the presence of a rotating disc.

    Tilt-compensated spirometer

    Tilt-compensated type spirometer also known as the AME Spirometer EVOLVE. This new spirometer can be held horizontally while taking measurements. If the patient leans too far forward or backward, the spirometer's 3D-tilt sensing compensates and indicates the patient position.

    References

    Spirometer Wikipedia


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