THE INFLUENCE OF EXTRACORPOREAL MEMBRANE-OXYGENATION ON CEREBRAL OXYGENATION AND HEMODYNAMICS IN NORMOXEMIC AND HYPOXEMIC PIGLETS

The objective of this study was to compare the effect of extracorporea l membrane oxygenation (ECMO) on cerebral oxygenation and hemodynamics in normoxemic and hypoxemic piglets. Six hypoxemic and six normoxemic piglets were put on venoarterial ECMO after cannulation of the right common carotid artery and external jugular vein with careful priming t o avoid hemodilution. Changes in cerebral concentrations of oxyhemoglo bin (cO(2)Hb), deoxyhemoglobin (cHHb), (oxidized-reduced) cytochrome a a(3) (cCyt.aa(3)), and blood volume (CBV) were continuously measured b y near infrared spectrophotometry. Heart rate, arterial O-2 saturation (Sao(2)), arterial blood pressure, pulsatility ratio of systemic circ ulation (calculated as systolic-diastolic/mean arterial blood pressure ), central venous pressure, intracranial pressure, and left common car otid artery blood flow (LCaBF) were simultaneously measured. We found that the cannulation procedure resulted in increased CBV, cHHb, and LC aBF in both groups. At 60 and 120 min after starting ECMO, the values of cO(2)Hb, CBV, and LCaBF in both groups were significantly higher th an precannulation values, while the pulsatility ratio decreased. In th e hypoxemic groups cHHb decreased and Sao(2) increased as well. No sig nificant changes of other variables were found. Between hypoxemic and normoxemic groups no significant differences in the response of CBV an d LCaBF at 60 and 120 min were found. We conclude that in piglets cann ulation for ECMO resulted in cerebral venous congestion and compensate d increase in LCaBF. After starting ECMO, the cerebral O-2 supply incr eased due to increased arterial O-2 content. It was accompanied by sim ilar increase of CBV in both groups, probably as a result of hyperperf usion, which seems to be related to the ECMO procedure itself.