Journal of Clinical Monitoring and Computing

, Volume 17, Issue 1, pp 43–52 | Cite as

The Automatic Lung Parameter Estimator (ALPE) System: Non-Invasive Estimation of Pulmonary Gas Exchange Parameters in 10-15 Minutes

  • Stephen Edward Rees
  • Søren Kjærgaard
  • Per Thorgaard
  • Jerzy Malczynski
  • Egon Toft
  • Steen Andreassen


Objective.Clinical measurements of pulmonary gas exchangeabnormalities might help prevent hypoxaemia and be useful in monitoringthe effects of therapy. In clinical practice single parameters are oftenused to describe the abnormality e.g., the “effectiveshunt.” A single parameter description is often insufficient,lumping the effects of several abnormalities. A more detailed picturecan be obtained from experiments where FIO2 is varied and twoparameters estimated. These experiments have previously taken30–40 minutes to complete, making them inappropriate for routineclinical use. However with automation of data collection and parameterestimation, the experimental time can be reduced to 10–15 minutes.Methods.A system has been built for non-invasive, Automatic,Lung Parameter Estimation (ALPE). This system consists of a ventilator,a gas analyser with pulse oximeter, and a computer. Computer programscontrol the experimental procedure, collect data from the ventilator andgas analyser, and estimate pulmonary gas exchange parameters. Use of theALPE system, i.e. in estimating gas exchange parameters and reducingexperimental time, has been tested on five normal subjects, two patientsbefore and during diuretic therapy, and on 50 occasions in patientsbefore and after surgical intervention. Results.The ALPE systemprovides estimation of pulmonary gas exchange parameters from a simple,clinical, non-invasive procedure, automatically and quickly. For normalsubjects and in patients receiving diuretic therapy, data collection byclinicians familiar with ALPE took (mean ± SD) 13 min 40 sec± 1 min 23 sec. For studies on patients before and after surgery,data collection by an intensive care nurse took (mean ± SD) 10min 47 sec ± 2 min 14 sec. Parameter estimates were: for normalsubjects, shunt = 4.95% ± 2.64% and fA2 = 0.89± 0.01; for patients with heart failure prior to diuretictherapy, patient 1, shunt = 11.50% fA2 = 0.41, patient 2 shunt =11.61% fA2 = 0.55; and during therapy: patient 1, shunt =11.51% fA2 = 0.71, patient 2, shunt = 11.22% fA2 = 0.49.Conclusions.The ALPE system provides quick, non-invasiveestimation of pulmonary gas exchange parameters and may have severalclinical applications. These include, monitoring pulmonary gas exchangeabnormalities in the ICU, assessing post-operative gas exchangeabnormalities, and titrating diuretic therapy in patients with heartfailure.

Pulmonary gas exchange hypoxaemia respiratory monitoring pulse oximetry 


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Copyright information

© Kluwer Academic Publishers 2002

Authors and Affiliations

  • Stephen Edward Rees
    • 1
  • Søren Kjærgaard
    • 1
    • 2
  • Per Thorgaard
    • 2
  • Jerzy Malczynski
    • 3
  • Egon Toft
    • 1
    • 3
  • Steen Andreassen
    • 1
  1. 1.Center for Model Based Medical Decision SupportAalborg University, Fredrik BajersvejAalborg, Denmark
  2. 2.Department of AnesthesiologyAalborg HospitalAalborgDenmark
  3. 3.Department of CardiologyAalborg HospitalAalborgDenmark

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