Quality Control Spirometry & Lung Volumes Gregg L. Ruppel, MEd, RRT, RPFT, FAARC Adjunct Professor, Pulmonary, Critical Care & Sleep Medicine Director, Pulmonary Function Laboratory St. Louis University Hospital

What Quality Control Is NOT !!

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

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

Spirometry Quality Spirometry 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

Accuracy and Precision 2.70 3.00 3.30 Mean 3.00 2.70 2.68 2.73 Mean 2.70 3.00 Accurate, but not very precise Precise, but not very accurate

Spirometry QC* Test How Often What To Do Volume Daily Calibration check using 3 L syringe Leak (volume spirometers) 3 cmH2O for 1 minute (< 30 ml volume loss) Volume linearity Quarterly 1 L volumes over entire range of device Flow linearity Weekly 3 flow ranges Timer Stopwatch Software Whenever changed Log and check biologic control * ATS/ERS 2005

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

Syringe Calibration Calibrating the Calibrator Annual calibration of syringe recommended

Calibration Check – Volume Spirometers Daily leak check Volume within ±3.5% of 3 L (2.895 – 3.105) Quarterly linearity check across volume range

Calibration Check – Volume Spirometers Is ± 3.5% good enough? * * McCormack et al. Chest 2007; 131:1486-1493

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

Calibration Check – Flow Spirometers

Calibration Check – Flow Spirometers

Other QC Techniques Syringe flow-volume loops (simulate patient) Biologic control (normal subject)

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)

Physical Calibration Body Box

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

Biologic Controls for Plethysmography Lung Volumes – Biologic Control Liters VTG TLCPLETH 2 subjects representative of patient population Perform VTG according to standard guidelines FRC and TLC should be within 10% of mean for each control

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)

N2 Washout QC 3 Liter syringe

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 < 0.02% for 10 minutes He analyzer linearity using serial dilutions - check quarterly

He Dilution QC Linearity Check

Lung Volumes QC Biologic* Control Mean 3.38 3.42 3.57 He N2 Box 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

Selecting Biologic Controls No history of respiratory disease (asthma) No symptoms Non-smoker (< 5 pk-yrs and 10 years quit) Readily available for testing

Handling Control Data

Biologic Control Data

Request “Generic Biocontrols” from Free Spreadsheet ! Request “Generic Biocontrols” from Maldonado@aarc.com

Biologic Control Data http://www.ezyqc.co.nz Disclosure: I received a free copy of the software as a beta tester

Biologic Control Data

Thanks ! Gregg Ruppel Pulmonary Function Lab St. Louis University Hospital ruppelgl@slu.edu