356 - A Descriptive Analysis of Cerebral Near Infrared Spectroscopy Curves following Birth in Neonates ≤1250 g and/or ≤30 weeks Gestation based on Common Influencing Factors

Poster Number: 356
Publication Number: 356.132

Sarah E. Kolnik, University of Washington School of Medicine, Seattle, WA, United States; Rebecca Marquard, Washington State University Elson S. Floyd College of Medicine, Spokane, WA, United States; Olivia C. Brandon, University of Washington School of Medicine, Roy, WA, United States; Janessa Law, University of Washington School of Medicine, Seattle, WA, United States; Mihai Puia-Dumitrescu, University of Washington School of Medicine, Seattle, WA, United States; Gregory C. Valentine, University of Washington, Tacoma, WA, United States; Tommy Wood, University of Washington School of Medicine, Seattle, WA, United States; Niranjana Natarajan, University of Washington School of Medicine, Seattle, WA, United States; Ulrike Mietzsch, University of Washington School of Medicine, Seattle, WA, United States

Background: There is limited granular data on baseline cerebral near-infrared spectroscopy (cNIRS) values in preterm neonates that measure the regional cerebral oxygen saturation (rScO2= O2Hb/(O2Hb+HHb).  As cNIRS readings are increasingly incorporated into clinical decision-making, it is imperative to understand the expected trajectory, differences across gestational ages (GA), and common influencing factors.

Objective: The aim of this study is to describe the trend of continuous cNIRS monitoring during the first 72 hours following birth and to understand factors influencing rScO2 in preterm infants without intraventricular hemorrhage (IVH).

Design/Methods: Retrospective single center cohort study including infants born at ≤1250 g and/or ≤30 weeks gestation who were monitored prospectively with continuous cNIRS during the first 72h after birth. NIRS curves were generated using generalized additive model fitting with start time of 6h after birth. Perinatal and postnatal factors known to influence cerebral perfusion were collected and cNIRS trajectories were analyzed based on clinical parameters split into two or three groups, either with numerical tertiles (GA, blood pressure) or clinically relevant cut-offs (hematocrit, pCO2). 

Results: Of the 98 infants, we excluded 32 infants, 2 with congenital abnormalities and 30 with IVH, leaving 66 (67%) infants for analysis. A total of 4252h of recorded cNIRS data were analyzed, captured in 5-10 sec intervals resulting in 2.3 million data points. Baseline characteristics are depicted in Table 1. A distinct shape of the cNIRS curve occurred across participants with the exception of the older GA infants (29-30wks) with a drop at 12 hours followed by a peak around 24-30 hours (Figure 1).   Perinatal factors associated with higher cNIRS curves were an older GA, Apgar >5 at 5 minutes of life, and CPAP after delivery room resuscitation (Figure 1).  Postnatal factors associated with highest cNIRS curve were hematocrit >45%, lowest CO2 >45mmHg, and diastolic pressure > 34mHg (Figure 2).   cNIRS readings stratified by GA did not correlate with postnatal factors and thus were not adjusted for in the figures. Conclusion(s): In the first 72 hours of life, expected trajectory of the cNIRS curves are different among gestational ages. Furthermore, cNIRS trajectories are significantly influenced by clinical factors. This knowledge offers the clinician a more accurate assessment of clinically meaningful deviations of trajectories. Future studies evaluating how these influencing factors and cNIRS trajectories impact outcomes will help the clinician target cNIRS goals.
Table 1
Figure 1