Mathematical Model for the Study of Hemorrhagic Shock and Fluid Resuscitation:The Systemic and Pulmonary Vasculature

摘要

In systemic and pulmonary circuit models, the number and configuration ofvascular compartments may affect predictions of vascular volume and blood flow. In this paper, we consider various models of the pulmonary and systemic vascular circuits to identify models appropriate for studies of hemorrhage and fluid resuscitation. We found that at least one pulmonary vascular compartment, made up of one resistance and one capacitance element, was required to describe the response of pulmonary blood volume to changes in pulmonary inflow rate (i.e., right heart output). Incorporation of additional pulmonary vascular segments did not adhere to predictions of pulmonary volume or flow rate. Therefore, one lumped pulmonary vascular compartment appears to be sufficient. It may be necessary to incorporate multiple pulmonary vascular segments, however, for studies of pulmonary transcapillary exchange or cardiovascular control. The initial model for the systemic circuit included a separate capillary compartment for studies of transcapillary exchange as well as variable resistance and compliance elements for studies of cardiovascular control. Model identification for the systemic circulation focused on the most appropriate number of parallel vascular pathways for predicting the response of systemic outflow (i.e., venous return) to changes in systemic inflow (i.e., left heart output). At least two separate parallel pathways were required to predict systemic outflow rate because of differences in the distribution time constant between skeletal muscle and other vascular beds. Model, Hemorrhage, Fluid resuscitation, Transcapillary exchange.