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Office spirometry e spirometria domiciliare: i requisiti minimi e loro rispondenza nelle strumentazioni attuali

Office spirometry e spirometria domiciliare: i requisiti minimi e loro rispondenza nelle strumentazioni attuali. Andrea Pelucchi & Antonio Foresi Servizio di Pneumologia e Fisiopatologia Respiratoria Sesto San Giovanni I° Congresso AIPO di Telemedicina Bari 29-30 Ottobre 2004.

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Office spirometry e spirometria domiciliare: i requisiti minimi e loro rispondenza nelle strumentazioni attuali

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  1. Office spirometry e spirometria domiciliare: i requisiti minimi e loro rispondenza nelle strumentazioni attuali Andrea Pelucchi & Antonio Foresi Servizio di Pneumologia e Fisiopatologia Respiratoria Sesto San Giovanni I° Congresso AIPO di Telemedicina Bari 29-30 Ottobre 2004

  2. John Hutchinson, 1811–1861, inventor of the spirometer. Reprinted with permission from Wellcome Trust Medical Photographic Library.

  3. Silhouette of John Hutchinson and his spirometer, illustrating correct body positioning for performance of the vital capacity maneuver Petty, T. L. Chest 2002;121:219S-223S

  4. Indication for Spirometry • Diagnosis • Early detection • Monitoring

  5. Essential Components of Valid Spirometry • Equipment Performance • Testing Technique • Measurement of Results • Technician Training Office spirometry, portable spirometr, handheld electronic spirometer home spirometers,office-based spirometers, standard spirometers

  6. TYPES OF SPIROMETERS • 1. Volumetric Spirometers: • Accumulate and directly measure exhaled air volume as a function of time; • Examples are water-sealed, dry rolling seal, and bellows spirometers; • Provide direct volume-time tracing; • In general, are precise, simple to operate, and easy to maintain; • May be slightly unwieldy due to size and weight.

  7. TYPES OF SPIROMETERS • 2. Flow-Type spirometers: • Indirectly measure airflow during exhalation; integrate the flows to obtain expired volume (pneumotachometer, turbine, hot wire anemometer, vortex, ultrasound beam) • Large range of flows are measured during a forced expiration: Flow sensors may perform better at high flow rates (early in maneuver) than at low flow rates (end of maneuver); • Often more variable (less precise) than volumetric spirometers; • Integrity of sensors must be maintained for accurate spirometry measurements - if sensor is damaged, blocked, or has moisture condensation or obstruction by mucus, test results may be erroneous; • Malfunctions in sensors, transducers, and electronics can go unnoticed - users must be alert for anomalous results; • Lightweight and portable.

  8. Factors to Consider when Choosing a Spirometer • A spirometer must: • be simple to use; • be safe and effective. Ensure compliance with spirometer and electrical safety standards; • be capable of simple routine calibration checking and have stable calibration which allows adjustments by the operator; • be robust and reliable, with low maintenance requirements; • provide graphic display of the manoeuvre; • utilise a sensor which is disposable or can be cleaned and disinfected; • be purchased from a reputable supplier who can provide training and servicing/repair; • be provided with a comprehensive manual describing its operation, routine maintenance and calibration; • use relevant normal predicted values; • be reasonably priced.

  9. American Thoracic Society. Standardization of spirometry, 1994 update. • Am J Respir Crit Care Med 1995;152,1107-1136

  10. MINIMAL RECOMMENDATIONS

  11. Petty TL, Weinmann GG.Building a national strategy for the prevention and management of and research in chronic obstructive pulmonary disease. National Heart, Lung, and Blood Institute Workshop Summary. Bethesda, Maryland, August 29-31, 1995. • JAMA 277:246-53;1997.

  12. Early assessment of respiratoryfunction in people at risk for chronic respiratory diseases……. Office Spirometers Must Only Report Values for FEV1, FEV6, and the FEV1/FEV6 Ratio

  13. Technical Requirements for Office Spirometers Advantagesof the newly proposed category of office spirometers for thispurpose include: • lower instrument cost • smaller size • less effortto perform the test • improved ease of calibration checks • an improved quality-assurance program Office spirometers shouldnot be utilized for diagnostic testing, surveillance for occupational lung disease, disability evaluations, or research purposes. Ferguson GT et al: Chest. 2000;117:1146-1161

  14. Sample volume-time curve illustrating differences between FVC- and FVC6-derived parameters Chest. 2003;124:1805-1811.

  15. van Schalkwyk EM, Schultz C, Joubert JR, White NW; • South African Thoracic Society • Standards of Spirometry Committee. Guideline for office spirometry in adults, 2004. • S Afr Med J. 2004 Jul;94(7 Pt 2):576-87. • Ferguson GT, Enright PL, Buist AS, Higgins MW. • Office spirometry for lung health assessment in adults: • A consensus statement from the National Lung Health • Education Program. • Chest. 2000 Apr;117(4):1146-61.

  16. Thenecessity for each new office spirometry system to have a "real-world"validation study before it is marketed. Ferguson GT et al: Chest. 2000;117:1146-1161 Each new office spirometry system must pass a “real world” validation study, ensuring that both the false positive and false-negative rates are less than 5 %. No spirometry system has completed such a validation study, however, and their “real world” accuracy is unknown Enright PL & Ferguson GT et al: Clin Chest Med 21:645-652;2000.

  17. Gold Standard

  18. Precision or Reproducibility • Is reliability • Indicates the ability of an instrument to yield the same measurement for a variable when the variable is measured repeatedly • Precision does not infer accuracy

  19. Accuracy or Validity • The ability of an instrument to measure its true value. • If accurate it is also valid and reliable (or precise) • Can be accurate at one level (magnitude) of measurement but inaccurate at others • Instruments should reflect acceptable accuracy over range of values you measure

  20. Ten patients were asked to perform the same maneuvers. They represented various degrees of severity of COPD G Liistro et al. – ERS 2004

  21. Coefficient of variability measured in the highly trained subjects G Liistro et al. – ERS 2004

  22. Bias ? Systematic error? 2 R = 0,2694 Bland & Altman Proportional error 1,2 1 0,8 0,6 Difference (reference-test) 0,4 0,2 0 1 2 3 4 5 6 -0,2 -0,4 Mean G Liistro et al. – ERS 2004

  23. G Liistro et al. – ERS 2004

  24. UNDERESTIMATION G Liistro et al. – ERS 2004

  25. Some devices presented a proportional error for some parameters

  26. Office-based spirometer value minus portable spirometer value vs mean of two values YES NO Mortimer, K. M. et al. Chest 2003;123:1899-1907

  27. Effect of errors on respiratory screening and surveillance programs Townsend, M. C. et al. Chest 2004;125:1902-1909

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