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. 2020 Aug 27;9(17):e015794. doi: 10.1161/JAHA.120.015794

Table 2.

Assessment of Accuracy Between 2 Inert Gas Rebreathing Methods

Patients Condition Qc Comparison No. of Data Points Qc, Mean (SD) r TE CV
Healthy, supine
Rest Fick vs N2O 52

Fick 6.4 (1.6)

N2O 6.6 (1.0)

 0.82 (0.71–0.89) 0.94 (0.79–1.17) 16.5 (13.9–20.9)
Rest Fick vs C2H2 51

Fick 6.3 (1.6)

Rebreathing 7.2 (1.0)

 0.85 (0.76–0.91) 0.84 (0.70–1.05) 14.5% (12.0–18.3)
Rest Thermodilution vs N2O 56

Thermodilution 7.2 (1.2)

N2O 6.6 (1.0)

 0.65 (0.46–0.78) 0.90 (0.76–1.11) 14.1 (11.8–17.7)
Rest, all loading conditions Thermodilution vs C2H2 2793

Thermodilution 5.5 (1.9)

Rebreathing 5.7 (2.0)

 0.84 (0.83–0.85) 1.02 (1.00–1.05) 19.5% (18.9–20.0)
Healthy, upright
Rest Fick vs N2O 54

Fick 4.5 (0.9)

N2O 4.1 (1.0)

 0.44 (0.19–0.63) 0.82 (0.69–1.01) 19.8 (16.3–25.0)
Exercise Fick vs N2O 57

Fick 16.9 (3.9)

N2O 11.8 (2.4)

 0.84 (0.74–0.90) 2.18 (1.84–2.68) 13.9 (11.6–17.3)
Rest Fick vs C2H2 117

Fick 5.3 (1.5)

Rebreathing 5.6 (1.5)

 0.77 (0.69–0.84) 0.94 (0.83–1.08) 20.2% (17.7–23.5)
Exercise Fick vs C2H2 114

Fick 15.4 (4.8)

Rebreathing 13.5 (3.7)

 0.87 (0.81–0.91) 2.39 (2.12–2.75) 16.5% (14.5–19.2)
Rest Thermodilution vs N2O 54

Thermodilution 4.8 (0.9)

N2O 4.1 (1.0)

 0.73 (0.57–0.83) 0.64 (0.54–0.80) 14.5 (12.0–18.2)
Exercise Thermodilution vs N2O 62 Thermodilution 15.8 (3.9) N2O 12.1 (2.3) 0.82 (0.72–0.89) 2.21 (1.88–2.69) 15.0 (12.6–18.6)
Exercise Thermodilution vs C2H2 98

Thermodilution 15.0 (4.1)

Rebreathing 13.3 (3.2)

 0.82 (0.75–0.88) 2.36 (2.06–2.74) 16.5% (14.3–19.4)
Healthy, supine/upright rest and upright exercise N2O vs C2H2 172

N2O 7.9 (3.8)

Rebreathing 8.9 (4.2)

 0.99 (0.98–0.99) 0.58 (0.52–0.65) 89 (8.1–10.1)

C2H2 indicates acetylene; CV, coefficient of variation; N2O, nitrous oxide; Qc, cardiac output; r, Pearson correlation coefficient; and TE, typical error.