Impact of brain injury on functional measures of amplitude-integrated EEG at term equivalent age in premature infants.

OBJECTIVE: To evaluate the association between qualitative and quantitative amplitude-integrated EEG (aEEG) measures at term equivalent age (TEA) and brain injury on magnetic resonance imaging (MRI) in preterm infants. STUDY DESIGN: A cohort of premature infants born at <30 weeks of gestation and with moderate-to-severe MRI injury on a TEA MRI scan was identified. A contemporaneous group of gestational age-matched control infants also born at <30 weeks of gestation with none/mild injury on MRI was also recruited. Quantitative aEEG measures, including maximum and minimum amplitudes, bandwidth span and spectral edge frequency (SEF90), were calculated using an offline software package. The aEEG recordings were qualitatively scored using the Burdjalov system. MRI scans, performed on the same day as aEEG, occurred at a mean postmenstrual age of 38.0 (range 37 to 42) weeks and were scored for abnormality in a blinded manner using an established MRI scoring system. RESULTS: Twenty-eight (46.7%) infants had a normal MRI or mild brain abnormality, while 32 (53.3%) infants had moderate-to-severe brain abnormality. Univariate regression analysis demonstrated an association between severity of brain abnormality and quantitative measures of left and right SEF90 and bandwidth span (ß=-0.38, -0.40 and 0.30, respectively) and qualitative measures of cyclicity, continuity and total Burdjalov score (ß=-0.10, -0.14 and -0.12, respectively). After correcting for confounding variables, the relationship between MRI abnormality score and aEEG measures of SEF90, bandwidth span and Burdjalov score remained significant. CONCLUSION: Brain abnormalities on MRI at TEA in premature infants are associated with abnormalities on term aEEG measures, suggesting that anatomical brain injury may contribute to delay in functional brain maturation as assessed using aEEG.

Empirical estimation of the normative blood pressure in infants <28 weeks gestation using a massive data approach.

OBJECTIVE: To determine the expected systolic, mean and diastolic blood pressures at birth and respective rates of change during the first 72 h of life in infants born at <28 weeks estimated gestational age (EGA) with a favorable short-term outcome, defined as survival to 14 days with grade II or less intraventricular hemorrhage (IVH). STUDY DESIGN: Systolic, mean and diastolic blood pressures were continuously sampled at 0.5 Hz via umbilical artery catheter from birth through 72 h. The raw data were aligned by postnatal hour and underwent error correction. For each infant, the mean values of systolic, mean and diastolic blood pressure were calculated for each postnatal hour. The slope and intercept of best-fit line for each of the three blood pressure parameters was then calculated. Infants that received inotropic medications, died in the first 14 days of life, or had IVH grade III or IV were excluded. RESULT: Using 11.9 million valid data points from 35 infants (mean EGA=25.7 ± 1.5 weeks, mean birth weight=865 ± 201 g), we found independent associations of African-American race (P<0.01) and a complete course of antenatal steroids (P<0.01) with higher blood pressures at birth and a slower rate of increase. Acute chorioamnionitis was independently associated (P=0.02) with lower blood pressures at birth and a faster rate of increase. EGA and birth weight were not independently predictive of blood pressure parameters. CONCLUSION: We found that (i) the estimated mean blood pressure at birth is ~33 mmHg in a cohort of very preterm infants, (ii) blood pressure gradually increases with postnatal age, (iii) systolic blood pressure increases at a faster rate than diastolic blood pressure, (iv) race, antenatal steroid exposure and chorioamnionitis are independent modulators of blood pressure whereas EGA and birth weight are not.