Am J Perinatol
DOI: 10.1055/s-0043-1761296
Original Article

Correlation of Renal Tissue Oxygenation to Venous, Arterial, and Capillary Blood Gas Oxygen Saturation in Preterm Neonates

1   University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin
2   Division of Neonatology, Department of Pediatrics, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin
,
Lauren Gadek
1   University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin
,
Amy C. Rothwell
1   University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin
,
Luke Richard
1   University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin
,
3   Division of Nephrology, Department of Pediatrics, Indiana University School of Medicine, Indianapolis, Indiana
4   Pediatric and Adolescent Comparative Effectiveness Research, Department of Pediatrics, Indiana University School of Medicine, Indianapolis, Indiana
,
Claudette O. Adegboro
1   University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin
2   Division of Neonatology, Department of Pediatrics, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin
› Author Affiliations
Funding Sources The authors had funding support from the UnityPoint Health Meriter Foundation and the Department of Pediatrics at the University of Wisconsin-Madison to support the purchase of NIRS machines and sensors for this study.

Abstract

Objective The aim of the study is to assess the correlation of renal regional tissue saturation of oxygen (RrSO2) measured by near-infrared spectroscopy (NIRS) in preterm neonates to venous oxygen saturation (SvO2) obtained from umbilical venous catheters (UVCs), arterial oxygen saturation (SaO2) obtained from umbilical artery catheters (UACs), and capillary oxygen saturation (ScO2) from capillary heel blood draws.

Study Design A secondary analysis of a prospective RrSO2 monitoring study in preterm neonates born <32 weeks gestational age. Neonates with any blood gas obtained during RrSO2 monitoring were included. RrSO2 was compared with simultaneous O2 saturation using non-parametric Mann Whitney U-test and Spearman correlation coefficient.

Results In 35 neonates, 25 UVC, 151 UAC, and 68 heel capillary specimens were obtained. RrSO2 was lower than the median SvO2 (58.8 vs. 78.9, p <0.01), SaO2 (51.0 vs. 93.2, p <0.01), and ScO2 (62.2 vs. 94.25, p <0.01). RrSO2 values correlated to both SaO2 and ScO2 (r = 0.32; p <0.01, r = 0.26; p = 0.03), but not SvO2 (r = 0.07; p = 0.74).

Conclusion In this secondary analysis, RrSO2 was consistently lower than blood gas O2 saturations and correlated with SaO2 and ScO2 but not SvO2. Lack of a correlation to SvO2 could be due to the small UVC sample size limiting statistical power. Future studies should prospectively evaluate if RrSO2 truly primarily reflects venous oxygenation in preterm neonates.

Key Points

  • Renal oxygenation correlates with arterial and capillary oxygen saturation.

  • Renal oxygenation did not correlate with venous oxygenation from umbilical venous catheters.

  • Studies are needed to determine if renal oxygenation primarily reflects venous or arterial oxygen.

Statement of Ethics

Patients (or their parents or guardians) gave their written informed consent, and the study protocol was approved by the UnityPoint Health Meriter ethical review board on human research, IRB approval number 2017–013.


Authors' Contributions

M.W.H. was the principal investigator who contributed to study design, analysis, interpretation of the data, and writing of the manuscript. L.G. did the data collection, analysis of data, and writing of manuscript. A.C.R. and L.R. did the data collection and review of the manuscript. M.C.S. and C.A. did the critical revision of the manuscript for important intellectual content. All authors approved the final version of the manuscript.




Publication History

Received: 15 August 2022

Accepted: 15 December 2022

Article published online:
29 January 2023

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