Reproduction of inert gas and oxygenation data: a comparison of the MIGET and a simple model of pulmonary gas exchange

Abstract

The simple model provides a description of lung damage and arterial oxygenation which is comparable to the MIGET, calculating PaO(2) with acceptable accuracy and precision over the clinically relevant range of PaO(2), and for different values of FIO(2), positive end-expiratory pressure (PEEP), and inspiratory-to-expiratory ratio (I:E).

Effect of low inspired oxygen fraction on respiratory indices in mechanically ventilated horses anaesthetised with isoflurane and medetomidine constant rate infusion

“…The main causes of hypoxaemia during anaesthesia, 50 which can be difficult to treat, are intrapulmonary shunt and ventilation-perfusion (V A :Q) mismatch 51 (Rees et al, 2010). Other potential causes of hypoxaemia include (1) hypoventilation, which can be 52 corrected by mechanical ventilation; and (2) diffusion limitation, which although unlikely to be 53 encountered in healthy horses, occurs at high intensity exercise (Wagner et al, 1989).…”

The Intelligent Ventilator (INVENT) project: The role of mathematical models in translating physiological knowledge into clinical practice

“…Reproduced from [24] Calculated values of anatomical dead space were almost identical for the MIGET and simple models, with a bias and standard deviation of the difference between these values equal to 0.002 The results of question 2 are illustrated in figure 4, taken from [25]. Figure 4 shows that the simple model provides a description of arterial oxygenation at different values of F I O 2 which is both comparable to the MIGET and accurate.…”

“…This comparison has been performed in two phases: first to see if the ALPE model could fit the experimental data provided by MIGET in health and disease, i.e. data describing the retention and excretion of inert gasses [24]; second, to determine whether the models could simulate changes in arterial oxygenation seen in health and disease in a form comparable to MIGET [25]. A summary of these studies follows: Seven pigs were anesthetized, muscle relaxed, and mechanically ventilated (volume controlled mode), and following infusion of MIGET tracer gasses and an equilibration period of 45 min, baseline measurements of hemodynamic and ventilatory parameters were taken and a determination of ventilation-perfusion distribution was performed using MIGET.…”

“…These data were then used to answer the following questions [24,25] 1) Can the ALPE model adequately describe MIGET data in a physiological situation analogous to acute lung injury, and does it give similar parameter values to the MIGET model? [24] 2) Can the MIGET and simple model give accurate and comparable predictions of P a O 2 across a range of PEEP, Inspiratory : Expiratory (IE) ratio, and F I O 2 settings compatible with clinical treatment of acute lung injury?…”

“…[24] 2) Can the MIGET and simple model give accurate and comparable predictions of P a O 2 across a range of PEEP, Inspiratory : Expiratory (IE) ratio, and F I O 2 settings compatible with clinical treatment of acute lung injury? [25] The results of question 1 are illustrated in table 1, taken from [24]. Table 1 gives the values of ALPE parameters when fitted to inert gas data, plus the weighted residual sum of squares (WRSS) of the fitting.…”