Quality Control Spirometry

1
Quality ControlSpirometry Lung Volumes

• Gregg L. Ruppel, MEd, RRT, RPFT, FAARC
• Adjunct Professor, Pulmonary, Critical Care
• Sleep Medicine
• Director, Pulmonary Function Laboratory
• St. Louis University Hospital

2
What Quality Control Is
NOT !!
3
What Quality Control Is
Quality control (QC) is a procedure or set of
procedures intended to ensure that a manufactured
product or performed service adheres to a defined
set of quality criteria or meets the requirements
of the client or customer. QC is similar to, but
not identical with, quality assurance (QA).
IT Department Johns Hopkins University
4
Calibration vs. Quality Control

• Calibration adjusts the output of an instrument
  (spirometer, gas analyzer) to match a known input
• Quality control tests an instrument to verify
  that the output is accurate and/or precise

5
Spirometry Quality
Spirometer
Methods
meets ATS/ERS recommendations
calibration
patient coaching
software
environmental factors
open vs. closed
Q/C
Spirometry Acceptability Repeatability
disease state
supervision
training competency
cooperation effort
age
feedback
language
motivation
Patients
Technologist
6
Accuracy and Precision
2.70 2.68 2.73 Mean 2.70
2.70 3.00 3.30 Mean 3.00
3.00
Accurate, but not very precise
Precise, but not very accurate
7
Spirometry QC
Test How Often What To Do
Volume Daily Calibration check using 3 L syringe
Leak (volume spirometers) Daily 3 cmH2O for 1 minute (lt 30 ml volume loss)
Volume linearity Quarterly 1 L volumes over entire range of device
Flow linearity Weekly 3 flow ranges
Timer Quarterly Stopwatch
Software Whenever changed Log and check biologic control
ATS/ERS 2005
8
Calibration/Verification Syringes

• 3 Liter recommended
• 15 ml or 0.5 full scale
• 3.5 for spirometer calibration checks
• Keep syringe at same conditions as spirometer
• Computerized syringes

9
Syringe CalibrationCalibrating the Calibrator
Annual calibration of syringe recommended
10
Calibration Check Volume Spirometers

• Daily leak check
• Volume within 3.5 of 3 L (2.895 3.105)
• Quarterly linearity check across volume range

11
Calibration Check Volume Spirometers

• Is 3.5 good enough?

McCormack et al. Chest 2007 1311486-1493
12
Calibration Check Flow Spirometers

• Volume within 3.5 of 3 L (2.895 3.105)
• 3 Flows between 0.5 12 L/sec (inject volume
  between 6 seconds and 0.5 seconds)
• Weekly linearity (high, medium, low flows)
• Disposable flow sensors check 1 at least daily

13
Calibration Check Flow Spirometers
14
Calibration Check Flow Spirometers
15
Other QC Techniques

• Syringe flow-volume loops (simulate patient)
• Biologic control (normal subject)

16
Body Plethysmograph QC

• Flow transducer accuracy same as for spirometry
• Box pressure and mouth pressure transducers
  calibrated (physical) daily
• Isothermal lung analog ( 50 ml or 3)
• Biologic controls (2 subjects monthly or when
  problems are suspected)

17
Physical Calibration Body Box
18
Isothermal Lung Analog

• Subject sits in box with jar (holds breath)
• Compress hand bulb at 0.5-1.0 Hz
• Record VTG tangent
• Calculate FRC of jar ATPS
• Volume of jar volume of water connectors
  metal wool

19
Biologic Controls for Plethysmography

• 2 subjects representative of patient population
• Perform VTG according to standard guidelines
• FRC and TLC should be within 10 of mean for each
  control

20
N2 Washout Lung Volume QC

• Flow or volume transducer meets standards for
  spirometry
• N2 analyzer zeroed with 100 O2 spanned with air
  (78.1 0.5)
• Linearity check every 6 months with certified gas
  or dilution technique (0.5 of expected)
• Adjustable large volume syringe (3 L) may be used
  to simulate patient maneuver
• Biologic controls (monthly)

21
N2 Washout QC
3 Liter syringe
22
He Dilution Lung Volume QC

• Check for leaks every 24 hours or after circuit
  changes
• Check water level if necessary
• Check gas conditioning columns (CO2, water)
• Check function of fan or blower
• He analyzer stable drift lt 0.02 for 10 minutes
• He analyzer linearity using serial dilutions -
  check quarterly

23
He Dilution QC
Linearity Check
24
Lung Volumes QC
Biologic Control
Mean 3.38 3.42 3.57 std 0.15 0.20 0.15 cv 4.5
5.7 4.3 N 11 11 12
Looks good on your resume
25
Selecting Biologic Controls

• No history of respiratory disease (asthma)
• No symptoms
• Non-smoker (lt 5 pk-yrs and 10 years quit)
• Readily available for testing

26
Handling Control Data
27
Biologic Control Data
28
Free Spreadsheet !

• Request Generic Biocontrols from
• Maldonado_at_aarc.com

29
Biologic Control Data
http//www.ezyqc.co.nz
Disclosure I received a free copy of the
software as a beta tester
30
Biologic Control Data
31
Thanks !

• Gregg Ruppel
• Pulmonary Function Lab
• St. Louis University Hospital
• ruppelgl_at_slu.edu