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208 Cardiovascular Support in Low Birth Weight Infants and Cerebral Hemodynamics: A Randomized Blinded Clinical Trial

Background: The decisition to treat systemic hypotension in LBWI is based on the belief of keeping adecuate organ perfusion. However, the impact of vasopressor treatment on cerebral tissue perfusion has not been systematically evaluated on the basis of a controlled clinical trial. Aims: To explore the effects on brain hemodynamics of two inotropes used to treat hypotension in LBWI.Methods: Newborns <1501g BW or <31 wk GA, with mean blood pressure (MAP) h, were randomly assigned to DP (2.5, 5, 7.5, 10 μg/K/min) (n=27) or EP (0.125, 0.250, 0.375, 0.5 μg/K/min) (n=32), increased in stepwise fashion every 20 min until the desired MAP (MAP-OP) was attained and maintained. Outcome measures: Quantitative changes in cerebral concentrations of oxyhemoglobin (HbO) and deoxyhemoglobin (HbR), cerebral intravascular oxygenation (ÄHbD) that is Ä(HbO-HbR), and cerebral blood volume (ÄCBV), were assesed by near infrared spectroscopy. Simultaneous MAP, heart rate (HR), trascutaneous PCO2/PO2 and peripheral oxygen saturation were continuously recorded and stored for latter analysis at: baseline (BL), at 20 min after each increase in dose (T1, T2, T3 and T4) until MAP-OP was reached, and then every 20 min up to 1 h of stable MAP-OP (60-OP).Results: BW and GA were 974±282 g and 27.9±2.3 wk, respectively. The studies were performed at a mean age of 5.3±3.7 hours of life. MAP-OP was achieved at: T1 DP 22.2%, EP 18.8%; T2 DP 33.3%, EP 28.1%; T3 DP 25.9%, EP 18.8%; T4 DP 14.8%, EP 28.1%. No differences were found in the rate of treatment failure (DP 3.7%, EP 6.3%). There was a significant linear increase in MAP, HR and ÄCBV from BL throughout the study period (p<0.001) without differences between the groups except for HR (higher in EP at MAP-OP and 60-OP, p<0.01). The increase in ÄCBV was coupled with a significant increase in ÄHbD. Changes in MAP were significantly correlated with ÄHbD at MAP-OP and at 60-OP. PCO2 and PO2 values remained unvaried. The effect of drug-dose escalation showed no differences in the variables' behaviour except for a higher HR in EP from 20 min after dose 2 (T2) and onwards (p<0.05 at T2). Drug-induced changes in cerebral hemodynamics varied according to GA.Conclusion: In hypotensive LBWI cardiovascular support with low-moderate dose DP or low-dose EP improve cerebral perfusion, as indicated by the increase in both ÄCBV and ÄHbD. Low-dose EP is as effective as low-moderate dose DP to increase MAP in LBWI.