CBF velocity in newborns 23-24 weeks' gestation during the first week of life

Objective: The aim of this prospective observational trial was to generate reference values of middle cerebral artery cerebral blood flow velocity (CBFv) in normotensive, ventilated newborn survivors born at 23-24 weeks' gestation during the first week (with normal cranial ultrasounds during the hospitalization), and to analyze how reference values may be affected by PCO₂. Methods: Baseline systolic, diastolic, and mean CBFv were determined for 12 infants born at 23-24 weeks' gestation (birth weight 643 ± 68 g) using transcranial Doppler ultrasound during several monitoring sessions during the first week, prior to intensive care procedures. Mean and 95% CI reference curves were generated using a locally weighted regression technique. Results: Mean CBFv increased from ~10 to 21 cm/sec, and when baseline PCO₂ was adjusted to 40, 50, and 60 mmHg, increased from ~8.5 to 9, ~12.5 to 16, and ~16.5 to 23 cm/sec during the first week, respectively. Conclusion: Reference curves for middle cerebral artery CBFv for normotensive ventilated newborns born at 23-24 weeks' gestation (with normal cranial ultrasounds) are presented for the first time. Since PCO₂ is a potent regulator of CBF, when reporting cerebral hemodynamic values in the future, investigators must also report PCO₂.