Understanding Cardiovascular and Pulmonary Interactions Using a New Integrated Cardiopulmonary Computational Model

Abstract

Background:

Understanding the complex interactions between cardiovascular and pulmonary physiologies is essential to the development of protective mechanical ventilation (MV) strategies. Computational modeling of the cardiopulmonary physiology can provide insights into these interactions and assists in the development of disease-specific ventilation protocols. In this study, we compared the normal and septic physiologic states, as predicted by an integrated cardiopulmonary computational model (ICM), which has been purposely constructed to study cardiopulmonary interactions, to existing preclinical data.

Methods:

The ICM is a lumped parameter model of the human cardiopulmonary system. The model predicts gas exchange and hemodynamics under a variety of conditions, depending on the mechanical ventilation settings, and the values that are assigned to the model parameters. The ICM outputs were compared to published normal and septic hemodynamic and gas exchange data.¹ We varied the inputs: ventilation rate, PEEP, peak inspiratory pressure (PIP), heart contractility, systemic vascular resistance (SVR) and heart rate (HR). The model outputs: mean arterial pressure (MAP), stroke volume (SV) and the ratio of partial pressure of oxygen and the fraction of inspired oxygen (P/F) were compared to the published results.¹

Results:

For both normal and septic physiology, the MAP, SV and P/F results from the model closely replicated the experimental data (Table 1). Significant reductions in heart contractility and SVR were consistent with the reported hemodynamic values during sepsis.

Conclusions:

The ICM successfully recapitulated hemodynamic and gas exchange parameters measured during normal and septic conditions. Our computational model is capable of simulating a variety of pathophysiological states, that could ultimately be used for the development of effective ventilation strategies during different disease states. </br> Reference: 1. Ziebart A, et al. Low tidal volume pressure support versus controlled ventilation in early experimental sepsis in pigs. Respir Res 2014;15(1):101.

Comparison of experimental data and computational results for normal and sepsis physiology

		Experimental Data			Model Results
Parameter	Units	Normal	Sepsis 3h	Sepsis 6h	Normal	Sepsis 3h	Sepsis 6h
MAP	[mmHg]	96	68	73	89	71	71
SV	[ml]	70	51	43	63	52	43
P/F	[mmHg]	475	190	190	500	201	200
Contractility	[mmHg/ml]				10	0.9	0.7
SVR change	[%]				4	-7	19