Determination of Cardiac Output in Pulmonary Hypertension Using Impedance Cardiography

Abstract

Background: Cardiac output (CO) is a prognostic factor in pulmonary hypertension (PH). Right heart catheterisation using the direct Fick method or thermodilution (TD) is the reference technique for CO measurement. Impedance cardiography (IPc) is a known non-invasive method of measuring CO. Objectives: In our study, we assume that the measurement of CO by IPc using the PHYSIOFLOW® system is as accurate as TD or using the direct Fick method in patients with PH in group 1 or group 4. Methods: A total of 75 patients were enrolled in a prospective study carried out at the hypertension reference centre of Toulouse University Hospital. Right heart catheterisation was performed for the diagnosis or follow-up of the disease. CO was measured using the Fick method, TD, and IPc simultaneously. A Bland-Altman analysis was plotted. Results: CO was 5.7 ± 1.9 L/min as measured by the Fick method, 5.4 ± 1.5 L/min by TD, and 5.5 ± 1.7 L/min by IPc. The bias between CO measurements by IPc and the direct Fick method was 0.149 L/min (95% CI, –0.298 to 0.596). The bias between CO measurements by IPc and the TD method was –0.153 L/min (95% CI, –0.450 to 0.153). The correlation decreased with the more extreme CO values (< 3 L/min or > 7 L/min). A few factors changed the agreement between measurements (BMI or membership in group 4). Conclusion: To conclude, this study shows that the measurement of CO by IPc in PH patients is reliable compared to the direct Fick method and TD obtained by right heart catheterisation. This accuracy decreases for extreme CO values.

Improvement of Hemodynamic Parameters in Patients With Preserved Left Ventricular Systolic Function by Catheter Ablation of Atrial Fibrillation ― A Prospective Study Using Impedance Cardiography ―

“…Impedance cardiography (ICG) is a noninvasive method of evaluating SV based on measurement of the thoracic bioimpedance. [8][9][10][11][12][13] Being a noninvasive method, ICG can be performed repeatedly, even in the outpatient clinic setting. Furthermore, sequential measurements of A trial fibrillation (AF), the most common sustained tachyarrhythmia observed in clinical practice, is related to potentially serious complications and death.…”

Determination of Cardiac Output: A Game of Thrones

“…In other words, for a true CO value of 5.5 L/min, the estimation of CO using IPc could range from 3.0 to 7.0 L/min assuming that the DF measure is close enough to the true value. Dupuis et al [1] also demonstrated PEs of 22.5 and 21% for IPc when compared to DF and TD, respectively. The narrow PEs are inconsistent with the wide LoA obtained from the Bland-Altman plot.…”

“…In their article published in this issue of Respiration , Dupuis et al [1] compared impedance cardiography (IPc) with DF and TD in a population of pulmonary hypertension patients. They concluded that IPc is reliable compared to the DF and TD methods.…”

“…Dupuis et al [1] claimed to find a good correlation ( r = 0.186 and 0.365, p < 0.001) when comparing IPc to DF and TD, respectively. These correlations are statistically significant, differing from 0, but is this enough in the clinical setting?…”

“…In the field of CO, some authors proposed that the LoA should be ≤1 L/min [4], and Critchley and Critchley [4] suggested a PE ≤30% when comparing a tested method to the reference method TD. Dupuis et al [1] found a mean bias < 0.2 L/min and wide LoA (±2.5 L/min) when comparing IPc to TD and DF. In other words, for a true CO value of 5.5 L/min, the estimation of CO using IPc could range from 3.0 to 7.0 L/min assuming that the DF measure is close enough to the true value.…”