title: Clinical evaluation of a new tracheal impedance cardiography method.
abstract: Non-invasive cardiac output measurement by means of impedance cardiography has been evaluated before, and agreement with other methods has been variable. We decided to study a newly developed tracheal impedance device, that is claimed to be more accurate and reliable. This incorporates new software and mathematical formulae, that are designed to reduce signal noise from diathermy, leading to improved accuracy. In 25 cardiothoracic surgery patients, simultaneous measurements were performed using both pulmonary artery thermodilution and the tracheal impedance device, at five peri-operative time points: before skin incision; after weaning from cardiopulmonary bypass; after sternal closure; and 30 min and 2 h after arrival in the intensive care unit. Mean cardiac output, bias and 95% limits of agreement were 5.3, 0.03 and -2.8 to 2.8 l.min(-1) , respectively. Tracheal impedance showed good correlation with measurement trends using thermodilution in 88% of measurements, with a mean (95% limit of agreement) angular bias of -9.0° (-83.3 to 65.3°). However, the wide limits of agreement and high percentage error of 53% that were apparent in this study mean that, in its present guise, tracheal impedance is not an acceptable alternative to thermodilution in cardiac surgical patients.
authors.affiliation: Amphia Hospital, Breda and Oosterhout, the Netherlands.
authors.forename: S C J
authors.initials: SC
authors.lastname: van der Kleij
authors.forename: B B
authors.initials: BB
authors.lastname: Koolen
authors.forename: D A
authors.initials: DA
authors.lastname: Newhall
authors.forename: B M
authors.initials: BM
authors.lastname: Gerritse
authors.forename: P M J
authors.initials: PM
authors.lastname: Rosseel
authors.forename: T A
authors.initials: TA
authors.lastname: Rijpstra
authors.forename: F E A
authors.initials: FE
authors.lastname: Geisler
authors.forename: N J M
authors.initials: NJ
authors.lastname: van der Meer
mesh_terms: D000368:Aged; D002302:Cardiac Output; D002307:Cardiography, Impedance / Q000295:instrumentation / Q000379:methods*; D002315:Cardiopulmonary Bypass; D001026:Coronary Artery Bypass; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D016343:Monitoring, Intraoperative / Q000295:instrumentation / Q000379:methods; D008991:Monitoring, Physiologic / Q000295:instrumentation / Q000379:methods; D019990:Perioperative Care / Q000295:instrumentation / Q000379:methods; D010865:Pilot Projects; D011182:Postoperative Care / Q000379:methods; D011651:Pulmonary Artery / Q000503:physiopathology; D015203:Reproducibility of Results; D013815:Thermodilution / Q000379:methods