Open AccessCardiac output measurement during exercise in COPD: A comparison of dye dilution and impedance cardiography
Author(s) -
Louvaris Zafeiris,
Spetsioti Stavroula,
Andrianopoulos Vasileios,
Chynkiamis Nikolaos,
Habazettl Helmut,
Wagner Harrieth,
Zakynthinos Spyros,
Wagner Peter D.,
Vogiatzis Ioannis
Publication year - 2019
Publication title -
the clinical respiratory journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.789
H-Index - 33
eISSN - 1752-699X
pISSN - 1752-6981
DOI - 10.1111/crj.13002
Subject(s) - impedance cardiography , limits of agreement , medicine , copd , pulmonary disease , cardiac output , cardiology , mean difference , heart rate , stroke volume , nuclear medicine , hemodynamics , confidence interval , blood pressure
Impedance cardiography (IC) derived from morphological analysis of the thoracic impedance signal is now commonly used for noninvasive assessment of cardiac output (CO) at rest and during exercise. However, in Chronic Obstructive Pulmonary Disease (COPD), conflicting findings put its accuracy into question. Objectives We therefore compared concurrent CO measurements captured by IC (PhysioFlow: CO IC ) and by the indocyanine green dye dilution method (CO DD ) in patients with COPD. Methods Fifty paired CO measurements were concurrently obtained using the two methods from 10 patients (FEV 1 : 50.5 ± 17.5% predicted) at rest and during cycling at 25%, 50%, 75% and 100% peak work rate. Results From rest to peak exercise CO IC and CO DD were strongly correlated ( r = 0.986, P < 0.001). The mean absolute and percentage differences between CO IC and CO DD were 1.08 L/min (limits of agreement (LoA): 0.05‐2.11 L/min) and 18 ± 2%, respectively, with IC yielding systematically higher values. Bland‐Altman analysis indicated that during exercise only 7 of the 50 paired measurements differed by more than 20%. When data were expressed as changes from rest, correlations and agreement between the two methods remained strong over the entire exercise range ( r = 0.974, P < 0.001, with no significant difference: 0.19 L/min; LoA: −0.76 to 1.15 L/min). Oxygen uptake (VO 2 ) and CO DD were linearly related: r = 0.893 ( P < 0.001), CO DD = 5.94 × VO 2 + 2.27 L/min. Similar results were obtained for VO 2 and CO IC ( r = 0.885, P < 0.001, CO IC = 6.00 × VO 2 + 3.30 L/min). Conclusions These findings suggest that IC provides an acceptable CO measurement from rest to peak cycling exercise in patients with COPD.