MEANS FOR QUALITATIVE AND QUANTITATIVE DESCRIPTION OF THE CARDIO-PULMONARY SYSTEM OPERATION WITHIN IRREVERSIBLE THERMODYNAMICS WITH FINITE SPEED

Abstract

Illness and aging are irreversible processes, which inevitably affects us all. The answers to the questions how, why, and how much irreversible are the cardio-respiratory system processes, will allow improved design of artificial hearts and lungs (vital “spare parts"), and health care before passing various pathological "thresholds of irreversibility" that generate diseases and premature aging. Onsager (1930) and then Prigogine (Nobel Price laureates) have shown that biological processes comply with Second Law of Thermodynamics (Entropy existence and growth), not only with First Law (transformation and conservation of energy), which was already accepted in Physiology and Biology. They created Linear Phenomenological Irreversible Thermodynamics (LPIT) that, so far, is the basis of irreversibility research in Biology and Physiology, but has not been substantially applied in the field of Thermal Machines. The Thermodynamics with Finite Speed (TFS), this new branch of Irreversible Engineering Thermodynamics used the LPIT of Onsager and Prigogine in its mathematical approach. Thus, it contains "the core of its essential and fundamental", but, in addition, it is adapted and developed to describe the irreversible processes in any thermal machines. Our belief that biological systems (people, animals, birds, fish) are a kind of natural thermal machines (not invented and built by engineers), allowed us to hope that TFS can provide tools for a qualitatively and quantitatively description of these systems or parts of them. A very important part is the cardio-respiratory system. This paper deals with the heart-lung interaction in the frame of TFS, aiming to generate means of qualitative and quantitative description of the oscillating processes taking place inside. The main average momentary parameters are introduced to describe these processes, adapted to this new domain. The purpose of the analysis is to establish a "Thermodynamic Scheme of Operation" of these subsystems in interaction, together with a new diagram so called PV/Px diagram for the description of irreversible processes in Pulmonary Cardiovascular System

Keywords: Cardio-Pulmonary SystemArtificial HeartDirect MethodThermodynamics with Finite SpeedStirling Machines PerformancesHeart Efficiency and PowerPV/Px Diagram for Heart