Late-onset neonatal sepsis (LOS) in very low birth weight (VLBW) preterm infants varies in severity from mild to fatal and often presents with cardiorespiratory instability. We hypothesized that heart rate (HR) and systemic oxygenation (SpO2) patterns would differ based on pathogen type and mortality.

We analyzed HR and SpO2 changes before LOS diagnosis for Gram-negative, Coagulase-negative Staphylococcus, and other Gram-positive bacteria (GN, CONS, OGP) and compared survivors and nonsurvivors. Using continuous every-2-second vital sign data from 365 VLBW infants in four neonatal intensive care units, we calculated nine HR and SpO2 metrics over a 96-hour window.

GN LOS was associated with a slightly higher HR, more negative skewness of HR, and higher cross correlation of HR-SpO2. Mortality was highest in GN LOS (22.7 vs. 4.6% CONS, 8.8% OGP). Nonsurvivors had distinct HR and SpO2 patterns.

These findings highlight critical cardiorespiratory differences at LOS diagnosis associated with mortality risk.

Changes in HR and SpO2 patterns varied by organism type prior to late-onset sepsis in VLBW infants.

Generally, HR and SpO2 pattern changes showed only small differences based on organism class.

Patterns associated with fatal sepsis included lower mean SpO2 and lower standard deviation of HR.

This study was approved by the Institutional Review Board at each site with a waiver of consent (approval number: 21237 at UVA). This study was conducted in accordance with the Declaration of Helsinki.

Namasivayam Ambalavanan4, Colm P. Travers4, Rachel Benz4, Karen D. Fairchild1, Brynne A. Sullivan1, Sherry L. Kausch1, Angela K.S. Gummadi1, Ian German Mesner1, Douglas A. Lake1, Katy Nash Krahn1, Jiaxing Joy Qiu1, J. Randall Moorman1, Carie Taveras2, Rakesh Sahni2, Joseph Isler2, Nim Goldshtrom2, Zachery A. Vesoulis3, Amanda Duncan3

* A list of authors and their affiliations appears at the end of the paper in “Note” section.

Received: 03 July 2025

Accepted: 30 August 2025

Article published online:
12 September 2025

© 2025. Thieme. All rights reserved.

Thieme Medical Publishers, Inc.
333 Seventh Avenue, 18th Floor, New York, NY 10001, USA