Medical & Biological Engineering & Computing

, Volume 46, Issue 1, pp 55–59

A new capnograph based on an electro acoustic sensor

Original Article

DOI: 10.1007/s11517-007-0228-4

Cite this article as:
Folke, M. & Hök, B. Med Bio Eng Comput (2008) 46: 55. doi:10.1007/s11517-007-0228-4


End tidal carbon dioxide measurements with an electro acoustic capnograph prototype have been demonstrated. The aim of this study was to verify that it is possible to obtain an adequate capnogram using the prototype and to investigate the influence of ambient temperature and humidity variations. By simultaneous measurements with a reference capnograph, on subjects performing exercise, hypo- and hyperventilation, PETCO2 readings from the reference were compared with the output signal from the prototype. The capnogram from the prototype correlated well with the reference in terms of breath time. The first parts of the expiration and inspiration phases were steeper for the reference than the prototype. The output signal from the prototype correlated well with the reference PETCO2 readings with a correlation coefficient of 0.93 at varied temperature and relative humidity.


End tidalCarbon dioxideElectro acoustic sensorCapnometryRespiratory monitoring

Copyright information

© International Federation for Medical and Biological Engineering 2007

Authors and Affiliations

  1. 1.Department of Computer Science and ElectronicsMälardalen UniversityVästeråsSweden
  2. 2.Hök Instrument ABVästeråsSweden
  3. 3.IDEMälardalen UniversityVästeråsSweden