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Behaviour of Organspecific pO2 and pCO2 Metabolisms of a Novel, Closed, Extracorporeal Mini-Perfusion Circuit in a Pediatric Animal Model
Pero Curcic1, Ismar Ovcina1, Drago Dacar1, Jakub Krumnikl2, Wolfgang Marte2, Thomas Marko2, Igor Knez1, Karlheinz Tscheliessnigg1.
1Division of Cardiac Surgery, Department of Surgery, Medical University of Graz, Graz, Austria, 2Department of Anesthesiology, Medical University of Graz, Graz, Austria.
OBJECTIVE:
Cardiopulmonary bypass (CPB) has multiple adverse effects, especially in a pediatric setting. Higher transfusion requirements and microcirculatory disturbances are some of the negative sequels. Closed circuit CPB has shown significantly better results in an adult population. In a multidisciplinary congenital animal laboratory model, organ specific parenchymal pO2/pCO2 changes and metabolic variables detected from the parieto-temporal lobe of cerebrum, the left ventricular myocardium and the right hepatic lobe were simultaneously measured.
METHODS:
Newly developed fibre-optical sensors, combined with a phosphorescent dye were used for pO2 measurement. PCO2 was detected by fibre-optical sensors on basis of phase modulation fluorometry, both constructed for continuous monitoring. The sensors were calibrated for an in-vivo setting. Hemodynamic and respiratory variables were recorded and adjusted to a predefined congenital cardiosurgical perfusion model. Samples of arterial, central-venous and intracranial bulbo-venous metabolic variables were recorded at timepoints defined by the study protocol. The animals were randomized to group P-MEC® (Pediatric Mini Extracorporeal Circuit, yet not available on free market, Medtronic™, 7 pigs, 10.6 ± 2.9 kg) and to group CPB (conventional cardiopulmonary bypass, 7 pigs, 10.5 ± 2.7 kg); the perfusion systems were minimized (priming volume of 282.8 ± 37.3 ml in P-MEC) and adjusted to basic variables comparable to congenital extracorporeal perfusion settings. After baseline measurements (T1) cardiopulmonary bypass was induced (T2), the aorta was crossclamped for 90 min. (T3-T8) the test animals were reperfused for 30 min. (T9-T10) and reobserved for another 30 min. off-bypass (T11-T12).
RESULTS:
There were no differences in preoperative metabolic and hemodynamic variables. Significantly higher need for both blood transfusion (395.7±47.2 ml vs. 28.5±14.8 ml) and higher lactate levels were detected in group CPB (p≤0.0001). ANOVA for repeated measurements at T1-T12 revealed significantly higher cerebral pO2 levels (p=0.007) in P-MEC® group, while pCO2 levels appeared similar. In contrast, both hepatic and myocardial pCO2 levels were higher in CPB group (p=0.004), while pO2 levels reacted homogenously.
CONCLUSIONS:
Under standardized conditions and without compromising safety, P-MEC® produced less lactate, and showed significantly favourable results concerning O2/CO2 metabolism and transfusion requirements in a congenital animal model.
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