Borderline hypotension: how does it influence cerebral regional tissue oxygenation in preterm infants?

Aim: To monitor cerebral regional tissue oxygenation (crSO(2)) of preterm infants continuously and to analyze the influence of arterial hypotension on crSO(2). Methods: In this prospective, observational study crSO(2), peripheral oxygen saturation (SpO(2)), heart rate (HR) and mean arterial blood pressure (MABP) were monitored continuously for 24 h, starting within the first 6 h after birth. Furthermore, cerebral fractional tissue oxygen extraction (cFTOE) was calculated. Preterm neonates with and without arterial hypotension (MABP below the gestational age in weeks) were compared to each other. Results: Forty-six preterm infants could be analyzed, 17 with (33.4 +/- 1.9 weeks, 2016.5 +/- 548.5 g) and 29 without arterial hypotension (33.3 +/- 1.3 weeks, 1924.7 +/- 451.9 g). Altogether, we detected 30 episodes of hypotension, with a mean duration of 1.6 +/- 1.2 h per infant and a mean decrease in MABP of 2.2 +/- 0.9 mmHg. During hypotension mean crSO(2) was 7 5 +/- 11%, 2 h prior to that 76 +/- 10% and 2 h after the hypotension 7 7 +/- 10%, therefore no significant alterations could be observed. Moreover, there was no significant difference in mean 24-h crSO(2), SpO(2) and cFTOE between the two groups. Conclusion: Mild short-term hypotensive episodes in preterm infants did not affect crSO(2). This suggests that cerebral autoregulation is maintained in case of borderline-hypotension and may protect infants from cerebral injury.