Physiological relevance of a minimal model in healthy pigs lung

Mechanical Ventilation (MV) is the primary form of support for acute lung injury and acute respiratory distress (ALI/ARDS) patients. However, intra- and inter- patient variability makes consistent care difficult and encourages the use of modeling approach to assist in patient-specific MV treatment. A minimal model is tested in 9 healthy pigs and subsequently in 3 ARDS pigs to evaluate its performance and physiological relevance for both conditions, as well as change in condition. The model estimates the mean of threshold opening pressure (TOP), mean threshold closing pressure (TCP) and standard deviation (SD) of both the TOP and TCP distribution for the animal at each different condition. The median percentage fitting error during inflation healthy and ARDS is less than 7.0% across all animals, indicating that the model is capable of capturing the fundamental lung mechanics during PEEP increase. An increase of mean TOP is observed between healthy and ARDS animal, suggesting higher pressure is required to recruit injured and collapsed lung during ARDS. The minimal model was able to capture the characteristic of both healthy and ARDS lungs, and it is able to track disease progression between states. It thus offers potentially opportunity to guide clinical decision making.