MD/PhD Student Loma Linda University Loma Linda, California, United States
Background: Premature neonates are at risk for retinopathy of prematurity (ROP), an eye disease that can lead to blindness due to abnormal retinal vascular growth. Neonates receiving supplemental oxygen have increased risk, as retinal vascularization is typically guided by physiologic hypoxia. Assessment of ROP presence and severity is accomplished by repeated, routine eye examinations, which include the use of mydriatic eye drops and physical manipulation of the eye using lid speculum and scleral indentation. Despite the use of pain-relieving interventions, such exams are accompanied by signs of neonatal pain, as well as tachycardia or bradycardia, and hypoxemia. Mesenteric oxygen is known to be decreased during the ROP exam. However, the impact on markers of hypoxia and ATP degradation remains unclear. The uric acid-to-creatinine concentration ratio ([UA]/[Cr]) has been validated as a neonatal urine biomarker of hypoxia and ATP degradation. Objective: This study investigates urinary [UA]/[Cr] in preterm neonates receiving supplemental oxygen or room air for 24 hours pre- and post- ROP examination. We hypothesize that the ROP exam results in increased [UA]/[Cr] in premature neonates, with higher trends in neonates receiving supplemental oxygen versus room air. Design/Methods: Study protocol and informed consent documents were approved by the study site IRB. Data collection and sample processing are complete. Analysis is currently underway, with planned completion date of 11/30/23. Urine was collected for 24 hours before and after clinically required ROP examination, into cotton balls placed over the urethral meatus of premature neonates (25-32 weeks gestational age) who received supplemental oxygen (N=23) or room air (N=19). Samples were analyzed in triplicate using high-performance liquid chromatography, and standard curves, with 2-aminopurine internal standard, were utilized to determine concentrations of uric acid and creatinine. Sample measurements of [UA]/[Cr] with coefficients of variation of less than 10% will be analyzed using repeated measures analysis of variance.
