Influence of ventilation mode on blood oxygenation - Investigation with Polish virtual lungs and Italian model of circulation

Positive alveolar (PÀ) and thoracic (PT) pressures during artificial ventilation disturb pulmonary circulation, and might influence arterial blood oxygenation (PaO2). Initial analysis of such influence of different artificial ventilation modes is thè goal of this paper. Previously elaborated virtual respiratory System (IBIB PAS, Warsaw, Poland) and cardiovascular System model (ICP CNR, Rome, Italy) were connected with two files-buffers to work as one virtual cardio-pulmonary System. Dependence of PaO2 on two methods (continuous inspiratory airflow (VCV) or pressure (PCV)), two ventilatory frequencies (JV= 15 or 7.5/min), and two values of thè minute ventilation (Kmin = 6 or 8L/min) was investigated. Perfusion dependence on gravity was neglected as thè virtual patient was in thè supine position. Simulations showed that whenJV = 15/min, neither thè used method nor fmin influence pulmonary blood flow significantly, whereas they influence thè flow during expiration when/K= 7.5 (blood flow falls more for PCV and Kmin = 8 L/min). Kmin more significantly influences alveolar partial pressure of oxygen (PO2) when/K = 15/min. PO2 was greater for PCV. As effects on thè flow and PO2 were contradictory, PaO2 was almost independent of thè used method and jV. It depended on Kmin more significantly if/K= 15/min