Assessing Cardiac Flow Measurements Using a Noninvasive Photoplethysmography-Based Device Compared to Invasive Pulmonary Artery Catheter

Background: Invasive monitoring is considered the gold standard for hemodynamic monitoring, yet it poses inherent risks. Objectives: The aim of the study was to compare invasive hemodynamic measurements using a noninvasive wearable photoplethysmography-based (PPG) monitor and an invasive pulmonary artery catheter. Methods: Heart failure patients undergoing right heart catheterization were recruited. The PPG-based monitor was applied, and readings of cardiac output (CO) and systemic vascular resistance (SVR) commenced in parallel to invasive hemodynamic measurements and CO calculations using indirect Fick's (IF) and thermodilution (TD) methods. Bland-Altman plots and Pearson correlations were used to assess the accuracy and agreement between the techniques. Limits of agreement below ±30% compared to TD were regarded as highly concordant. Results: A total of 90 patients (56.6% [51/90] men, mean age 62 ± 16 years) were included in the final analysis. The limits of agreement and bias (lower/upper limit of 95% CI) for CO and SVR were −19.1/14.5%, −2.3% (−4.2/−0.4%) and −27.4/12.3%, −7.5% (−9.7/−5.2%) for the PPG compared to the TD; −28.6/29.8%, 0.5% (−2.7/3.8%) and −42.3/20.5%, −10.9% (−14.4/−7.3%) for the PPG compared to IF method; and −46.1/34.1%, −6.0% (−10.6/−1.3%) and −26.8%/58.3%, 15.7% (10.7/20.7%) for the TD compared to the IF method. Pearson coefficients (lower/upper limit of 95% CI) between the PPG method and the TD, the PPG method and IF, and the TD and IF were 0.959 (0.938/0.974), 0.844 (0.767/0.897), and 0.775 (0.668/0.851) for CO, and 0.936 (0.902/0.959), 0.865 (0.796/0.911) and 0.687 (0.546/0.79) for SVR, respectively. Similar correlations and biases were found with different BMIs and skin color tones. Conclusions: The PPG-based device correlates well with invasive methods.