PHYSIOLOGICAL TARGET CONTROL IN LONG-TERM EXTRACORPOREAL OXYGENATION

Objectives: The application of long-term extracorporeal lung assist is still limited in clinical practice. Apart from long term material issues of oxygenator and blood pump also the usage scenario Itself poses major Implications on the design of the whole treatment system. While in the OR such machi...

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Veröffentlicht in:International journal of artificial organs 2011-08, Vol.34 (8), p.625-625
Hauptverfasser: Walter, M, Brendle, C, Arens, J, Stollenwerk, A, Kopp, R, Bensberg, R, Leonhardt, S
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Sprache:eng
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Zusammenfassung:Objectives: The application of long-term extracorporeal lung assist is still limited in clinical practice. Apart from long term material issues of oxygenator and blood pump also the usage scenario Itself poses major Implications on the design of the whole treatment system. While in the OR such machines are continuously operated by dedicated personnel, in the ICU operation and supervision are only intermittent or triggered by alarms. Especially the "easy" task of setting the appropriate machine parameters requires continuous readjustment of machine operating-values to patient demand and condition. In order to achieve this, we developed a closed loop control system which enables the direct control of physiological target values. Methods: A fully computer controllable ECLA system featuring a centrifugal blood pump and an electronic fresh gas mixer was set up. Additional measurement equipment for blood flow and on-line blood gases was integrated into the external circuit and supplemented by an extended patient monitoring. A cascaded control scheme was developed and implemented on a DSPACE real time control system. The inner control loop is used to control the oxygenator output gas concentrations. This enables the independent control of O sub(2) and CO sub(2) gas transfer. The outer control loop then uses this to control physiological target values of venous CO sub(2) and arterial O sub(2) saturation. Results: The control scheme was tested in an animal trial study of 8 pigs. By applying hypoxic gas concentrations at insufficient levels of minute ventilation, lung failure was simulated. Our physiologic control was tested at different levels of simulated lung failure. During 90% of the time target values could be kept within close boundaries. Conclusions: Physiological target control is one of the key issues in treating lung failure with long-term ECLA. We could show the feasibility of our approach and its robustness against disturbances.
ISSN:0391-3988