Medical and Biological Engineering and Computing

, Volume 35, Issue 6, pp 752–756 | Cite as

Two-point calibration procedure of the forced oscillation technique

  • K. N. Desager
  • M. Cauberghs
  • K. P. Van de Woestijne


The forced oscillation technique is usually calibrated by loading the measuring device with a known impedance. A correction function is calculated, relating the measured and reference impedances at each frequency. However, this one point calibration procedure does not account for transducer asymmetry. A procedure has previoously been presented to circumvent this problem: in addition to one known reference impedance, the callbration was repeated with the system occluded (infinite impedance). The aim of the present study was to evaluate a variant of this procedure, in which instead of resorting to an extreme condition imposing high requirements on the flow measuring system, two reference loads of 4 and 50 hPal−1s were measured, thus covering the range of impedances obsereved in children and infants (a two-point procedure). The calibration procedure was performed with these two impedances and evaluated with a third impedance of ∼ 17 hPal−1 s. The results of three calibration procedures were compared: one-point, two-point and a previously reported calibration procedure. Impedances consisted of sintered glass and mesh wire screens mounted in glass or polyvinyl tubes. For low impedance values, in the range of 4 to 17 hPal−1s, measured and predicted values were similar for the three calibration procedures at frequencies from 4–52 Hz, although with the one point calibration procedure there was some underestimation above 44 Hz. With the highes load, especially above 32 Hz, marked discrepancies between measured and predicted values were observed with the one-point calibration procedure and the previously reported calibration procedure. Under these circumstances the two-point procedure is preferred.


Calibration procedure Forced oscillation technique 


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. Cauberghs, M., andvan de Woestijne, K. P. (1991): ‘Calibration procedure of the forced oscillation technique’,Eur. Resp. Rev.,1, pp. 158–162Google Scholar
  2. Delavault, A., Saumon, G., andGeorges, R. (1980): ‘Identification of transducer defect in respiratory impedance measurements by forced random noise: correction of experimental data’,Resp. Physiol.,40, pp. 107–117CrossRefGoogle Scholar
  3. Desager, K. N., Buhr, W., Willemen, M., van Bever H. P., de Backer, W., Vermeire, P. A., andLandser, F. J. (1991): ‘Measurement of total respiratory system impedance in infants by the forced oscillation technique’,J. Appl. Physiol.,71, pp. 770–776Google Scholar
  4. Dubois, A. B., Brody, A. W., Lewis, D. W., andBurgess, B. F. (1956): ‘Oscillation mechanics of lungs and chest in man,’J. Appl. Physiol.,8, pp. 587–594Google Scholar
  5. Duvivier, C., Rotger, M., Felicio da Silva, J. F., Peslin, R., andNavajas, D. (1991). ‘Static and dynamic performances of variable reluctance and piezoresistive pressure transducers for forced oscillation measurements,’Eur. Respir. Rev.,1, pp. 146–150Google Scholar
  6. Farré, R., Navajas, D., Peslin, R., Rotger, M., andDuvivier, C. A. (1989): ‘A correction procedure for the asymmetry of differential pressure transducers in respiratory impedance measurements,’IEEE Trans. Biomed. Eng.,BME-36, pp. 1137–1140CrossRefGoogle Scholar
  7. Franken, H., Clement, J., andvan de Woestijne, K. P. (1983): ‘Systematic and random errors in the determination of respiratory impedance by means of the forced oscillation technique: a theoretical study,’IEEE Trans. Biomed. Eng.,BME-30, pp. 642–651Google Scholar
  8. Jackson, A. C., andVinegar, A. (1979): ‘A technique for measuring frequency response of pressure, volume and flow transducers’,J. Appl. Physiol.: Respirat. Environ. Exercise. Physiol.,47, pp. 462–467Google Scholar
  9. Landser, F. J., Nagels, J., Demedts, M., Billiet, L., andvan de Woestijne, K. P. (1976): ‘A new method to determine frequency characteristics of the respiratory system,’J. Appl. Physiol.,41, pp. 101–106Google Scholar
  10. Peslin, R., Jardin, P., Duvivier, C., andBegin, P. (1984): ‘In-phase rejection requirements for measuring respiratory input impedance,’J. Appl. Physiol.,56, pp. 804–809Google Scholar
  11. Turner, M. J., MaCleod, I. M., andRothberg A. D. (1989a): ‘Measurement of the frequency response and common mode gain of neonatal respiratory pressure and flow measurement systems, part 1: apparatus,’Clin. Phys. Physiol. Meas.,10, pp. 219–230CrossRefGoogle Scholar
  12. Turner, M. J., Macleod, I. M., andRothberg, A. D. (1989b): ‘Measurement of the frequency response and common mode gain of neonatal respiratory pressure and flow measurement systems, part 2: results’,Clin. Phys. Physiol. Meas.,10, pp. 231–240CrossRefGoogle Scholar

Copyright information

© IFMBE 1997

Authors and Affiliations

  • K. N. Desager
    • 1
  • M. Cauberghs
    • 1
  • K. P. Van de Woestijne
    • 1
  1. 1.Laboratorium voor PneumologieUZ GasthuisbergLeuvenBelgium

Personalised recommendations