Continuous Estimation of Cardiac Output in Critical Care: A Noninvasive Method Based on Pulse Wave Transit Time Compared with Transpulmonary Thermodilution

Figures

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  Figure 1. Comparison between COTPTD and COesCCO. (a) Correlation between COTPTD and COesCCO estimates at baseline. Each dot represents one patient. Correlation between the two estimates was significant (r = 0.742, p < 0.001). The regression coefficient was 0.52, and the intercept was 2.21 l/min (COesCCO = 0.52 × COTPTD + 2.21 l/min) indicating that at low CO, the esCCO was overestimated and at high cardiac output, underestimated CO as compared to the TPTD method. (b) The Bland–Altman plot of COTPTD and COesCCO, Each dot represents a pair of simultaneous cardiac output measurements by esCCO and TPTD of the same patient. The midhorizontal line marks the average difference between COTPTD and COesCCO (bias; 1.61 l/min). The upper and lower horizontal lines represent the 95% confidence interval of the difference between COTPTD and COesCCO (limits of agreement; −1.76 and +4.98 l/min). (c) The four quadrant plot of the correlation between ΔCOesCCO and ΔCOTPTD. Each dot represents the change of cardiac output over an 8-hour period (M8 h − Mmean baseline) assessed by transpulmonary thermodilution (TPTD) and continuous cardiac output (esCCO). The regression fitted (ΔCOesCCO = 0.35 × ΔCOTPTD − 0.09…

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  Figure 2. Comparison between COTPTD and COesCCO in patients with sepsis (a–c) and patients with neither sepsis nor trauma (d–f). (a) In patients with sepsis, correlation between COTPTD and COesCCO estimates at baseline was significant (r = 0.813, p=0.001), regression coefficient was 0.59, and the intercept was 1.82 l/min (COesCCO = 0.59 × COTPTD + 1.82 l/min); (d) in patients with neither sepsis nor trauma, correlation was significant (r = 0.669, p=0.002), regression coefficient was 0.41, and the intercept was 2.75 l/min (COesCCO = 0.41 × COTPTD + 2.75 l/min). In patients with sepsis (b) comparing COTPTD and COesCCO yielded a bias of 1.52 l/min and limits of agreement of −2.08 and +5.12 l/min; in patients with neither sepsis nor trauma (e), bias was 1.77 l/min and limits of agreement of −1.81 and +5.34 l/min. Estimates of the change in CO over the first 8 h (M8 h – Mmean baseline) was analyzed by four quadrant plots with regressions fitted. In patients with sepsis (c), ΔCOesCCO = 0.24 × ΔCOTPTD – 0.27 l/min, and for patients with neither sepsis nor trauma (f), ΔCOesCCO = 0.35 × ΔCOTPTD + 0.02 l/min.