Title: Office spirometry e spirometria domiciliare: i requisiti minimi e loro rispondenza nelle strumentazi
1Office 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
2John Hutchinson, 18111861, inventor of the
spirometer. Reprinted with permission from
Wellcome Trust Medical Photographic Library.
3Silhouette of John Hutchinson and his spirometer,
illustrating correct body positioning for
performance of the vital capacity maneuver
Petty, T. L. Chest 2002121219S-223S
4Indication for Spirometry
- Diagnosis
- Early detection
- Monitoring
5Office spirometry, portable spirometr, handheld
electronic spirometer home spirometers,office-base
d spirometers, standard spirometers
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8- 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.
9- 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.
10American Thoracic Society.
Standardization of spirometry, 1994 update. Am J
Respir Crit Care Med 1995152,1107-1136
11MINIMAL RECOMMENDATIONS
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13Early assessment of respiratory function in
people at risk for chronic respiratory diseases.
Office Spirometers Must Only Report Values for
FEV1, FEV6, and the FEV1/FEV6 Ratio
14Technical Requirements for Office Spirometers
- Advantages of the newly proposed category of
office spirometers for this purpose include - lower instrument cost
- smaller size
- less effort to perform the test
- improved ease of calibration checks
- an improved quality-assurance program
- Office spirometers should not be utilized for
diagnostic testing, surveillance for occupational
lung disease, disability evaluations, or
research purposes.
Ferguson GT et al Chest. 20001171146-1161
15Sample volume-time curve illustrating differences
between FVC- and FVC6-derived parameters
Chest. 20031241805-1811.
16 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
Jul94(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
Apr117(4)1146-61.
17The necessity for each new office spirometry
system to have a "real-world" validation study
before it is marketed.
Ferguson GT et al Chest. 20001171146-1161
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
21645-6522000.
18Gold Standard
19Precision 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
20Accuracy 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
21Ten patients were asked to perform the same
maneuvers. They represented various degrees of
severity of COPD
G Liistro et al. ERS 2004
22Coefficient of variability measured in the highly
trained subjects
G Liistro et al. ERS 2004
23Bland 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
24G Liistro et al. ERS 2004
25UNDERESTIMATION
G Liistro et al. ERS 2004
26Some devices presented a proportional error for
some parameters
27Office-based spirometer value minus portable
spirometer value vs mean of two values
YES
NO
Mortimer, K. M. et al. Chest 20031231899-1907
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29Effect of errors on respiratory screening and
surveillance programs
Townsend, M. C. et al. Chest 20041251902-1909