Effects of neurodevelopmental risk factors on brainstem maturation in premature infants.

BACKGROUND: Interpeak latencies (IPL), as measured by the auditory brainstem-evoked responses (ABR) test, represent the conduction time, and therefore the maturation of the brainstem auditory pathway. We aimed to study the effect of various risk factors for the neurodevelopmental delay on the conduction time in the auditory pathway among normal hearing premature infants, at term postmenstrual age (PMA). METHODS: Retrospective analysis of 239 premature infants (gestational age 32.5 ± 2.1 weeks, birth weight 1827 ± 483 g). Interpeak latencies, demographic data, and risk factors were recorded. RESULTS: Sex, PMA at ABR test, being small for gestational age (SGA), intraventricular hemorrhage (IVH) or periventricular leukomalacia (PVL), and days of invasive ventilation were found to significantly affect the IPL's in the auditory pathway in a univariate analysis. Multivariable regression analysis revealed that male sex and less advanced PMA at the examination were independent factors associated with prolonged IPL's, while bronchopulmonary dysplasia, IVH or PVL and being SGA shortened the IPL's. Non-invasive mechanical ventilation, did not affect the caudal part of the auditory pathway, despite its high noise level. CONCLUSIONS: Among various risk factors for the neurodevelopmental delay, male sex was associated with delayed, while IVH or PVL, BPD and SGA could be associated with accelerated auditory brainstem maturation. IMPACT: Auditory brainstem-evoked response (ABR) test, among normal hearing infants, can serve as a clinical tool to assess brainstem auditory maturation. Different neurodevelopmental risk factors could have different effects on the maturity of the auditory pathway. Male sex is significantly associated with prolonged interpeak latencies (IPL) among preterm and term infants, while intraventricular hemorrhage or periventricular leukomalacia, bronchopulmonary dysplasia, and being small for gestation age may be associated with shortened IPL The corrected age at ABR testing is of significance, among preterm and term infants.

The use of an early ACTH test to identify hypoadrenalism-related hypotension in low birth weight infants.

OBJECTIVE: To investigate if in preterm newborns, an early adrenocorticotropin hormone (ACTH) test can identify possible transient adrenal insufficiency (TAI), using significant hypotension as a clinical marker. STUDY DESIGN: We studied 40 premature newborns born 24 to 29 weeks gestational age (GA) before 8 h of life. Serum cortisol levels were obtained before and 40 min after administration of 1.0 mcg kg(-1) cosyntropin. Inotropes were used to treat hypotension based on clinical assessment following no response to fluid boluses. Functional echocardiogram was used to support the clinical diagnosis of hypotension. The accuracy of the ACTH test was evaluated using receiver operating characteristic (ROC) curve. RESULT: Study patients had mean GA of 26.6 weeks and birth weight of 876 g. In all, 30% required inotropes. The area under the ROC curve for the ACTH test was 87%. Using a cutoff of an increase in cortisol below 12% from baseline had 75% sensitivity and 93% specificity for detecting hypotension. This cutoff was associated with bronchopulmonary dysplasia (8/12 vs 7/28, 95% CI: 0.1 to 0.72), but not with other morbidities or death. CONCLUSION: An early ACTH test using the above cutoff has high specificity for detecting hypotension, and thus, can serve as a marker for potential TAI in preterm newborns. Future studies should focus on identifying those newborns for which steroid supplementation would be most beneficial.