Research in progress - Clinical Trial: Correlations with conventional measurements of lung function

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Clinical Partners Meeting - 20/03/2012 - Trinity College, Cambridge

Miss Jenny Conlon- Respiratory Physiologist/ Research Assistant

Addenbrooke's Hospital, Cambridge University Hospitals, Cambridge, UK

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  • Brief introduction
  • To include photo of crane set-up
  • Research in progress - Clinical Trial: Correlations with conventional measurements of lung function

    1. 1. Research in ProgressClinical Trial: Correlations withconventional measurements of lung functionMiss Jenny Conlon- Respiratory Physiologist/ Research Assistant 1
    2. 2. Conventional Measurements • Spirometry is one of the most common pulmonary function tests (PFTs) • Physiological test that measures the amount (volume) and/or speed (flow) of air that can be inhaled and exhaled • Spirometry is performed using a spirometer device which comes in several different varieties
    3. 3. Indications for Spirometry 1. Diagnostic e.g. assess pre-operative risk 2. Monitoring e.g. assess therapeutic intervention 3. Disability/ Impairment Evaluations e.g. assess patients as part of a rehabilitation programme 4. Public Health e.g. derivation of reference equations
    4. 4. Key Parameters • Vital Capacity (VC) / Forced Vital Capacity (FVC) (L) VC = The maximal volume of air exhaled from a maximal inspiration FVC = VC performed with a maximally forced expiratory effort • Forced Expiratory Volume in One Second (FEV1) (L.sec -1) Maximal volume of air exhaled in the first second of a forced expiration from a position of full inspiration • Peak Expiratory Flow (PEF) (L.min -1) Maximum expiratory flow achieved from a maximum forced expiration, starting without hesitation, from the point of maximum lung inflation 4
    5. 5. Spirometric Output 1. Volume-time curve
    6. 6. Spirometric Output 2. Flow-volume loop
    7. 7. Quality Control & Hygiene/Infection Control Test Minimal Action Interval Volume Daily Calibration check with 3-L syringe Leak Daily 3 cmH20 (0.3 kPa) constant pressure for 1 min Volume Quarterly 1-L increments with a calibrating syringe measured over entire Linearity volume range Flow Weekly Test at least 3 different flow ranges Linearity Time Quarterly Mechanical recorder check with stopwatch Software New Versions Log installation date and perform test using “known” subject 29 March 2012 7
    8. 8. Spirometry Standardisation Steps 29 March 2012
    9. 9. Simultaneous SLP & Spirometry Clinical Trial Title: Validation of SLP against Spirometry Sponsor: PneumaCare Limited Aim: Validate SLP by comparing tidal volume and forced expiration measurements obtained using SLP against simultaneous measurements via spirometry 29 March 2012 9
    10. 10. Methodology 1. Patient recruitment, inclusion/exclusion criteria 2. Spirometer set-up 3. SLP/PneumaScan set-up ( grid positioning, grid coverage) 4. Measurements (1 x tidal breathing and ~ 3 x forced manoeuvres)
    11. 11. Key Factors
    12. 12. Grid Coverage Grid coverage has been classified into three areas: • Low coverage • Medium coverage • High coverage
    13. 13. Low Coverage Example Projected grid not covering the abdomen, chest or sides
    14. 14. Medium Coverage Example
    15. 15. High Grid Coverage
    16. 16. Grid Positioning Grid coverage has been classified into two areas; • Low positioning • High positioning
    17. 17. Low Grid Positioning
    18. 18. High Grid Positioning
    19. 19. Movement• Estimated that ~10-15% of SLP volume measurements affected by patient movement• Movement during forced manoeuvres reduces the volume measured by SLP and increases the difference between SLP and spirometry data
    20. 20. Key Points for Consideration • Grid coverage and position accounts for the greatest inconsistency between techniques • Poor positioning and coverage can reduce the volume significantly • Movement during forced manoeuvres reduces the volume measured by SLP and increases the difference between SLP and spirometry data
    21. 21. Optimal Set-Up 29 March 2012 21
    22. 22. SLP Output 29 March 2012 22
    23. 23. Data Collection Total number of subjects tested = 108 Average number of data sets per subject = 4 Adults = 96 Active/previous lung disease = 53 "Healthy Others" = 43 Children (<18 years) = 12 Active/previous lung disease= 10 “Healthy Others”= 2 29 March 2012 24
    24. 24. Disease Types Respiratory Disease No. of Subjects COPD 16 Asthma 12 Pneumonia 6 Bronchiectasis 4 Cystic Fibrosis 5 “Other” 20 29 March 2012 25
    25. 25. Findings • Building on previous results obtained in Pilot and Trial studies with a CE marked device • Previous research: Strong correlations calculated between Spirometer and SLP data via waveform analysis for respiratory rate (r = 0.999), Vt (r = 0.967), and forced expiration (r = 0.98) • Current clinical trial: Progression to now displaying similar correlations on volume changes and flows between Spirometer and SLP data via integration and differentiation analysis
    26. 26. Findings 8 FVC 7 6 SLP FVC (l) 5 4 3 2 1 y = 1.006x + 0.435 R² = 0.902 0 0 1 2 3 4 5 6 7 Spirometry FVC (l) 29 March 2012 27
    27. 27. Findings 6 FEV1 5 4 SLP FEV1 (l) 3 2 y = 1.006x + 0.081 1 R² = 0.830 0 0 1 2 3 4 5 Spirometry FEV1 (l) 29 March 2012 28
    28. 28. Findings Tidal Volume 2 SLP VT (l) 1 y = 1.008x + 0.015 R² = 0.814 0 0 1 2 Spirometry VT (l) 29 March 2012 29
    29. 29. Findings Expiratory Time 7 6 5 SLP ET (s) 4 3 2 1 y = 0.978x + 0.116 R² = 0.875 0 0 1 2 3 4 5 6 7 Spirometry ET (s) 29 March 2012 30
    30. 30. Findings Inspiratory Time 4 3 SLP IT (s) 2 1 y = 0.870x + 0.177 R² = 0.871 0 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 Spirometry IT (s) 29 March 2012 31
    31. 31. Findings 7 FVC- Gender Analysis 6 5 4 SLP FVC (l) 3 Female 2 Male 1 0 0 1 2 3 4 5 6 7 Spirometry FVC (l) 29 March 2012 32
    32. 32. Other Research Projects 1. Validation of SLP in non-invasive ventilated COPD patients - Patients tested ~24 hours following exacerbation/admission and at 3 day intervals until discharge - Tidal breathing measurements taken both on and off non-invasive ventilation (NIV) where possible - Measurements recorded from NIV machine during measurements (i.e. respiratory rate, tidal volume) - Rating of perceived breathlessness recorded
    33. 33. Other Research Projects 2. Validation of SLP in non-ventilated neonates - Assessment of breathing patterns in new born neonates - Progression to validation of SLP in ventilated neonates - Use of alternate mount currently in development to allow placement of PneumaScan above incubator
    34. 34. Set-Up
    35. 35. Set-Up
    36. 36. Development of Set-Up
    37. 37. Summary • Solid base of data to build upon • ‘Learning process’ throughout recent data collection • Improved outcomes with focus to ‘key factors’ during measurements • Improved data collection via developments in device and software (i.e. real time system, alternate mount) • Continue to expand data collection across clinical populations
    38. 38. References • Miller, et al. ‘Standardisation of Spirometry’ (2005) • Rutala, et al. ‘Infection risks associated with spirometry’ (1991) • Leeming, et al. ‘Use of filters for the control of cross-infection during pulmonary function testing’ (1993) • Miller, et al. ‘General considerations for lung function testing’ (2005) • Miller, et al. ‘Interpretative strategies for lung function tests’ (2005)
    39. 39. Any Questions?

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