Challenges in zero-flow blood pressure as a measure of mean circulatory filling pressure: Experimental and computational perspectives.

Mean circulatory filling pressure (MCFP) is a foundational hemodynamic concept, representing the average circulatory pressure in a no-flow state and used to assess volume status and venous return. However, its measurement and clinical relevance remain debated. In this study, zero-flow pressures were recorded in 14 healthy pigs following cardiac arrest. Measurements were taken for 10 min in the abdominal aorta and right atrium under two conditions: cardiac arrest induced by pentobarbital overdose or by ventricular fibrillation (VF), with half of the VF animals rendered hypovolemic. A validated computational model of cardiovascular physiology was used to simulate these scenarios. Pentobarbital caused a rapid pressure equilibration, with mean arterial pressure (MAP) falling from 47 ± 3.7 to 16 ± 2.5 mm Hg. In contrast, VF produced a dynamic pressure response: MAP dropped from 53 ± 4.7 to 17 ± 2.2 mm Hg while central venous pressure rose, producing a persistent retrograde pressure gradient (5 ± 2.1 mm Hg). In silico simulations closely matched these dynamics (normalized RMSE <5%) and confirmed the influence of reflex mechanisms. These results challenge the idea of MCFP as a stable, universal value. Zero-flow pressures depend heavily on arrest method and reflexes, and computational modeling offers a valuable, ethical alternative to animal-based investigations.