Development of a Framework for the Hemodynamic Impact of Positive End-Expiratory Pressure in Normal and Heart Failure Conditions.

Positive end-expiratory pressure (PEEP) improves respiratory conditions. However, the complex interaction between PEEP and hemodynamics in heart failure patients makes it challenging to determine appropriate PEEP settings. In this study, we developed a framework for the impact of PEEP on hemodynamics considering cardiac function, by integrating the impact of PEEP in the generalized circulatory equilibrium framework, and validated the framework by assessing its ability to accurately predict PEEP-induced hemodynamics. In eight dogs, PEEP was increased stepwise, and hemodynamic responses were measured under normal, volume-loaded, and myocardial infarction (MI)-induced heart failure conditions. For predicting hemodynamics under PEEP using the proposed framework, the PEEP-intrathoracic pressure (ITP) relationship was empirically established in dogs. Hemodynamic parameters were estimated at each PEEP level based on the hemodynamics recorded without PEEP. The parameters were then used to predict hemodynamics under various heart conditions. The predicted and measured values were compared. Stepwise increase of PEEP decreased arterial pressure (AP) and cardiac output (CO). Left atrial pressure (LAP) decreased in normal hearts but increased in MI hearts. Predicted AP [R, 0.92; root mean squared error (RMSE), 6.3 mmHg], CO (R, 0.96; RMSE, 7.9 ml∙min∙kg) and LAP (R, 0.92; RMSE, 2.3 mmHg) matched measured values with high accuracy, irrespective of volume status or heart condition. In conclusion, we developed a framework for the hemodynamic impact of PEEP considering cardiac function and demonstrated its validity. The results indicate that the effects of PEEP on hemodynamics can be explained primarily by ITP, and are modulated by cardiac function.