Comment on: 'presentation of a novel method to estimate analog mean systemic filling pressure based on cardiac power'...

In response to the recent proposal by Monares-Zepeda et al. to estimate mean systemic filling pressure (MSFP) using cardiac power (CP) as a surrogate for the venous return pressure gradient (VRg), we raise concerns regarding the physiological validity and generalizability of the reported correlation. We demonstrate through simulation that the relationship between CP and VRg arises from structural mathematical coupling due to shared dependence on cardiac output (CO), and that this correlation weakens significantly (r = 0.54) when realistic physiological variability is introduced. We further argue that CP and VRg reflect distinct hemodynamic domains, and caution against interpreting their empirical correlation as evidence of physiological interchangeability. We call for broader validation of the model across diverse circulatory conditions. Comment on: 'Presentation of a novel method to estimate analog mean systemic filling pressure based on cardiac power' -on Correlation, Coupling, and Physiological Meaning.