The physiologic basis of spirometry.

Department of Pediatrics, University of Kentucky College of Medicine, Lexington KY 40536, USA.
Respiratory care (Impact Factor: 1.84). 12/2009; 54(12):1717-26.
Source: PubMed

ABSTRACT Spirometry is the most useful and commonly available tests of pulmonary function. It is a physiological test that measures individual inhalation and exhalation volumes of air as a function of time. Pulmonologists and general-practice physicians commonly use spirometry in their offices in the assessment and management of lung disease. Spirometric indices are well validated and easily interpreted by comparison with established normal values. The remarkable reproducibility of spirometry results from the presence of compliant intrathoracic airways that act as air flow regulators during forced expiration. Because of this anatomic arrangement, expiratory flow becomes dependent solely on the elasticity of the lungs and airway resistance once a certain degree of expiratory force is exerted. Insight into this aspect of respiratory physiology can help in the interpretation of spirometry.

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    ABSTRACT: Conventional oral spirometry is a commonly used test for respiratory functions. However, the nasal passages are the primary pathway for regulating ventilation and modulating ventilated air. Here, we tested the validity of using the nasal route (nasal spirometry) for the evaluation of respiratory functions. 250 healthy young adults (150 males and 100 females; 17 to 23 years of age) were subjected to two spirometry tests: oral spirometry by using a mouth piece and nasal spirometry by using a face mask. Measurement parameters included: Vital capacity (VC), forced vital capacity (FVC), forced expiratory volume first second (FEV1), FEV1/FVC%, Forced expiratory flow (FEF25/75%). and maximum voluntary ventilation (MVV). In both males and females, only VC was significantly higher in nasal than oral spirometry, while FVC, FEV1, FEV1/FVC % FEF25/75% and MVV were significantly higher in oral than nasal spirometry. Prediction equations for different measurements of nasal spirometry were derived by multiple regression analysis using sex, height, and weight as independent variables. We conclude that nasal spirometry could be a valid procedure which may be more real in expressing normal respiratory functions.
    Basic Sciences of Medicine. 01/2014; 3(2):30-35.
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    Pakistan Journal of Medical Sciences Online 01/2012; 28(1):71-74. · 0.10 Impact Factor
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    ABSTRACT: Background: Agricultural workers have an increased risk of respiratory diseases. Occupation and age among many other factors influence the lung function. Growing body of scientific literature from oversees have highlighted the decline in lung function with age in farmers and farm related workers. The aim of the present study was to assess the age related decline in lung function in agricultural workers since most of the Indian studies reported age related decline in lung function in general population but none in agricultural population. Methods: A total number of 64 healthy, non-smoking agricultural workers were divided into two groups according to their age. First group consisted of 31 subjects aged between 20-25 years and the second group consisted of 33 subjects aged between 26-40 years. Vital capacity (VC) and Peak Expiratory Flow Rate (PEFR) were measured using spirometry in both the groups. Vital Index was calculated from the vital capacity and body surface area. Results: Peak Expiratory Flow Rate was decreased significantly with advancing age in agricultural workers but not the Vital Capacity. Conclusion: Both obstruction to the air flow and senile degenerative changes in the lungs together might have played role in decreased PEFR in agricultural workers.
    International Journal of Medical and Health Sciences. 10/2012; 1.

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