Patient–Ventilator Interaction Testing Using the Electromechanical Lung Simulator xPULMTM during V/A-C and PSV Ventilation Mode

Abstract: During mechanical ventilation, a disparity between flow, pressure and volume demands
of the patient and the assistance delivered by the mechanical ventilator often occurs. This paper
introduces an alternative approach of simulating and evaluating patient–ventilator interactions
with high fidelity using the electromechanical lung simulator xPULM™. The xPULM™ approximates
respiratory activities of a patient during alternating phases of spontaneous breathing and
apnea intervals while connected to a mechanical ventilator. Focusing on different triggering events,
volume assist-control (V/A-C) and pressure support ventilation (PSV) modes were chosen to test
patient–ventilator interactions. In V/A-C mode, a double-triggering was detected every third
breathing cycle, leading to an asynchrony index of 16.67%, which is classified as severe. This asynchrony
causes a significant increase of peak inspiratory pressure (7.966.38 vs. 11.090.49cmH2O,
p < 0.01)) and peak expiratory flow (􀀀25.578.93 vs. 32.900.54 L/min, p < 0.01) when compared
to synchronous phases of the breathing simulation. Additionally, events of premature cycling were
observed during PSV mode. In this mode, the peak delivered volume during simulated spontaneous
breathing phases increased significantly (917.0945.74 vs. 468.4031.79 mL, p < 0.01)
compared to apnea phases. Various dynamic clinical situations can be approximated using this
approach and thereby could help to identify undesired patient–ventilation interactions in the future.
Rapidly manufactured ventilator systems could also be tested using this approach.

Keywords: biomedical engineering; breathing simulation; electromechanical lung simulator; patient–
ventilator interactions; rapidly manufactured ventilator systems testing