The effects of bolus compared to continuous administration of adrenaline on cerebral oxygenation during experimental cardiopulmonary resuscitation

Background: : Bolus administration of adrenaline during cardiopulmonary resuscitation (CPR) results in only short-term increases in systemic and cerebral perfusion pressure (CePP) with unclear effects on cerebral oxygenation. The aim of this study was to investigate the effects of bolus compared to continuous adrenaline administration on cerebral oxygenation in a porcine CPR model. Methods: : After five minutes of cardiac arrest, mechanical CPR was performed for 15 min. Adrenaline (45 lg/kg) was administered either as a bolus every five minutes or continuously over the same period via an infusion pump. Main outcome parameter was brain tissue oxygen tension (PbtO2), bt O 2 ), secondary outcome parameters included mean arterial pressure (MAP), intracranial pressure (ICP), CePP and cerebral regional oxygen saturation (rSO2) 2 ) as well as arterial and cerebral venous blood gases. Results: : During CPR, mean MAP (45 +/- 8 mmHg vs. 38 +/- 8 mmHg; p = 0.0827), mean ICP (27 +/- 7 mmHg vs. 20 +/- 7 mmHg; p = 0.0653) and mean CePP (18 +/- 8 mmHg vs. 18 +/- 8 mmHg; p = 0.9008) were similar in the bolus and the continuous adrenaline group. Also, rSO2 2 (both 24 +/- 6 mmHg; p = 0.9903) and cerebral venous oxygen saturation (18 +/- 12% versus 27.5 +/- 12%; p = 0.1596) did not differ. In contrast, relative P bt O 2 reached higher values in the continuous group after five minutes of CPR and remained significantly higher than in the bolus group until the end of resuscitation. Conclusion: : Continuous administration of adrenaline improved brain tissue oxygen tension compared with bolus administration during prolonged CPR.