1 / 52

RES 131

RES 131. Pulmonary Function Testing. Laboratory Instrumentation. TWO TYPES OF SPIROMETERS AVAILIBLE IN THE PFT LAB. VOLUME-DISPLACING Sometimes known as “volume collecting” FLOW-SENSING. VOLUME-DISPLACING SPIROMETERS. COLLECTS EXHALED AIR ACTS AS A RESEVOIR FOR INHALED AIR.

jaden
Download Presentation

RES 131

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. RES 131 Pulmonary Function Testing

  2. Laboratory Instrumentation • TWO TYPES OF SPIROMETERS AVAILIBLE IN THE PFT LAB. • VOLUME-DISPLACING • Sometimes known as “volume collecting” • FLOW-SENSING

  3. VOLUME-DISPLACING SPIROMETERS • COLLECTS EXHALED AIR • ACTS AS A RESEVOIR FOR INHALED AIR.

  4. WATER SEAL SPIROMETER • CONSISTS OF THREE CYLINDERS • ONE CYLINDER WITH OPENING ON TOP • SECOND CYLINDER WITH OPENING ON BOTTOM • THIRD CYLINDER BETWEEN 1ST AND 2ND WITH OPENING ON BOTTOM

  5. BELLOWS SPIROMETER • USUALLY CONSISTS OF : • SOFT FLEXIBLE BELLOWS • LATEX OR RUBBER • RIGID OR SEMI-RIGID PANELS ON EITHER SIDE OF THE BELLOWS

  6. DRY ROLLING SEAL • COMPRISED OF A PISTON IN A CYLINDER • USES A SOFT SILICONE BASED ELASTIC MATERIAL AS A SEALING COMPONENT • OLD SYSTEMS USED A LEATHER ROLLING SEAL

  7. DIAPHRAGM SPIROMETER • CONSISTS OF: • HOUSING • UPPER AND LOWER • DIAPHRAGM • PUSHER PLATE

  8. VOLUME DISPLACEMENT SPIROMETER'S • GENERALLY, BEFORE TESTING STARTS, THESE SPIROMETER'S ARE EMPTY • SOME TYPES ALLOW PRESETTING OR FILLING BEFORE TESTING

  9. DESIRABLE CHARACTERISTICS • DIRECTLY MEASURE VOLUME • LOW COST • EASE OF OPERATION • WATER-SEAL SPIROMETER IS CONSIDERED TO BE THE “GOLD STANDARD”

  10. UNDESIRABLE CHARACTERISTICS • SOME VERY LARGE AND BULKY • LESS PORTABLE • WATER MUST BE CHANGED • LEAKS • MANUAL CALCULATION REQUIRED IF NO MICROPROCESSOR

  11. FLOW-SENSING SPIROMETER'S • VOLUME IS CALCULATED BY MULTIPLYING: • FLOW BY TIME • THIS IS KNOWN AS “INTEGRATION” • REQUIRES A COMPUTER OR MICROPROCESSOR

  12. FOUR TYPES OF FLOW SENSING SPIROMETER'S • PNEUMOTACHOGRAPH • HOT-WIRE ANEMOMETER • TURBINE DEVICE • VORTEX DEVICE

  13. PNEUMOTACHOGRAPH • ALSO KNOWN AS “DIFFERENTIAL PRESSURE DEVICE” • TUBE WITH FIXED RESISTANCE • CONTAINS A BUNDLE OF CAPILLARY TUBES OR FINE MESH SCREEN(S)

  14. PNEUMOTACHOGRAPH • ACCURACY BASED ON FIXED RESISTANCE • CHANGES IN RESISTANCE AFFECT ACCURACY • WATER VAPOR • SECRETIONS • MANY ARE HEATED TO PREVENT CONDENSATION

  15. HOT-WIRE ANEMOMETER • FINE WIRE IN CENTER OF TUBE • AIR MOVING THROUGH THE TUBE COOLS THE WIRE • ELECTRICAL CURRENT IS PASSED THROUGH WIRE TO MAINTAIN TEMPERATURE • CURRENT NEEDED TO MAINTAIN TEMP IS MEASURED

  16. HOT-WIRE ANEMOMETER • UNABLE TO MEASURE TURBULENT FLOWS ACCURATELY • LONG TUBE REQUIRED TO CREATE LAMINAR FLOW • FRAGILE

  17. TURBINE DEVICE • TURBINE INCREASES SPEED WITH INCREASING FLOW • REVOLUTIONS ARE MEASURED • INERTIA CREATES INACCURACY

  18. TURBINE DEVICE • NOT AFFECTED BY: • TURBULENT FLOW • MOISTURE • GAS COMPOSITION

  19. VORTEX DEVICE • STRUTS IN AIRFLOW CAUSE TURBULENCE RESULTING IN A VORTEX • VORTEXES ARE COUNTED

  20. VORTEX DEVICE • NOT SENSITIVE ENOUGH TO MEASURE LOW FLOWS

  21. Flow Sensing Spirometers • DESIRABLE CHARACTERISTICS • SMALLER AND MORE PORTABLE • COMPUTERIZED, NO MANUAL CALCULATIONS • MANY PROVIDE QUICK REFERENCE VALUES • CAN MEASURE BI-DIRECTIONAL FLOW

  22. Flow Sensing Spirometers • UNDESIRABLE CHARACTERISTICS • MORE KNOWLEDGE REQUIRE TO OPERATE COMPUTER • FREQUENT AND CAREFUL CALIBRATION • MOISTURE AND SECRETIONS CAUSE INACCURACY • GAS COMPOSITION CAN AFFECT RESULTS • MAY NOT SENSE LOW FLOWS

  23. CHOOSING A SPIROMETER • RECOMMENDATIONS FOR SPIROMETER'S ARE PUBLISHED BY THE AMERICAN THORACIC SOCIETY • PUBLISHED IN 1979, 1987 AND THE LATEST IN 1995

  24. SPIROMETER'S FOR FORCED EXPIRATORY MANEUVERS • ABLE TO MEASURE VOLUMES OF AT LEAST 8 LITERS • FLOWRATES (INSPIRATORY AND EXPIRATORY) BETWEEN 0 AND 12 LITERS PER SECOND

  25. SPIROMETER'S FOR FORCED EXPIRATORY MANEUVERS • ABLE TO COLLECT OR MEASURE VOLUMES FOR 15 SECONDS • IF THE SPIROMETER IS USED TO MEASURE THE FEV1, THE BACK EXTRAPOLATION METHOD SHOULD BE USED

  26. SPIROMETRY DISPLAYS • TWO WAYS TO DISPLAY THE SPIROGRAM • VOLUME-TIME • FLOW-VOLUME

  27. VOLUME-TIME DISPLAY • VOLUME IS DISPLAYED ON THE Y AXIS (VERTICAL) • TIME IS DISPLAYED ON THE X AXIS (HORIZONTAL)

  28. VOLUME-TIME DISPLAY • USEFUL IN EVALUATING THE LENGTH OF A TEST MANEUVER • ALLOWS ASSESSMENT OF VOLUME PLATEAU DURING THE TERMINAL PORTION OF THE TRIAL

  29. FLOW-VOLUME DISPLAY • FLOW IS DISPLAYED ON THE Y AXIS (VERTICAL) • VOLUME IS DISPLAYED ON THE X AXIS (HORIZONTAL)

  30. FLOW VOLUME DISPLAY • MOST USEFUL IN EVALUATING THE START OF TEST • TYPICALLY, THE GRAPH IS SCALED SO THAT THE FLOW REPRESENTATION IS TWICE THAT OF THE VOLUME

  31. CALIBRATION OF PULMONARY FUNCTION INSTRUMENTATION • Without a conscientiously applied calibration program, pulmonary function instruments may generate erroneous information

  32. CALIBRATION • Calibration of volume collecting and flow sensing SPIROMETER'S require the use of a calibration syringe

  33. Calibration of volume collecting SPIROMETER'S • Patient testing tubing should be attached • Inject the entire calibration syringe volume • Observe the pen or graphic display

  34. Calibration of volume collecting SPIROMETER'S • If the display or line does not travel in a straight line, there is a leak • If no leak is present, the indicated volume should be equal the volume of the calibration syringe within +/-3%

  35. Calibration of volume collecting SPIROMETER'S • Calculation of acceptable calibration error • Multiply the syringe volume by 3% (.03) • 3.0 x .03 = .09 • Add and subtract the calculated value from the known value • 3.0 L + .09 = 3.09 L • 3.0 L - .09 = 2.91 L

  36. Calibration of flow- sensing SPIROMETER'S • This type of spirometer of ten has a menu option for calibration • At least one injection from the calibration syringe should be with a reported value within +/- 3% • Usually several injections are completed

  37. Calibration of flow- sensing SPIROMETER'S • ATS recommends varying the flow rate of the injections • Once at approx. 3 L/sec (1 second) • Once at approx. .05 L/sec (6 seconds) • Once at a rate between the previous two

  38. Calibration • If either type of spirometer cannot meet the accuracy standards, the spirometer may not be used. • Calibration must be completed at least daily or whenever accuracy is questioned

  39. Calibration • ATS standards require the documentation of the calibration • A log book should be kept, documenting the calibration values obtained

  40. Quality Control • Activities used to maintain Quality • Laboratory Standards • Quarterly testing of known subjects with stable pulmonary conditions • Recorder time sweep • Check the accuracy of the recorder by stop watch

More Related