Objective Thresholds of cerebral hypoxia through monitoring of near-infrared spectroscopy tissue oxygenation index (TOI) were used to investigate the relationship between intraventricular haemorrhage (IVH) and indices of hypoxia.
Design Prospective observational study.
Setting A single-centre neonatal intensive care unit.
Patients Infants <28 weeks’ gestation with an umbilical artery catheter.
Methods Thresholds of hypoxia were determined from mean values of TOI using sequential Χ2 tests and used alongside thresholds from existing literature to calculate percentage of time in hypoxia and burden of hypoxia below each threshold. These indices were then compared between IVH groups.
Results 44 infants were studied for a median of 18.5 (range 6–21) hours in the first 24 hours of life. Sequential Χ2 analysis yielded a TOI threshold of 71% to differentiate between IVH (16 infants) and no IVH (28 infants). Percentage of time in hypoxia was significantly higher in infants with IVH than those without, using thresholds of 60%–67%. Burden of hypoxia was significantly higher in infants with IVH than without, using thresholds of 62%–80%. With the threshold of 71%, percentage of time in hypoxia was lower by 12.2% with a 95% CI of (−25.7 to 1.2) (p=0.073), and the burden of hypoxia was lower by 29.2% hour (%h) (95% CI −55.2 to −3.1)%h (p=0.012) in infants without IVH than those with IVH.
Conclusions Using defined TOI thresholds, infants with IVH spent higher percentage of time in hypoxia with higher burden of cerebral hypoxia than those without, in the first 24 hours of life.
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Contributors Substantial contributions to the conception or design of the work: CSdaC, PS, MC and TA. Acquisition, analysis or interpretation of data for the work: IHXN, CSdaC and FAZ. Drafting the article: IHXN. Revising the article critically for important intellectual content and final approval for publication: all authors.
Funding CSdaC was supported by SPARKS charity (11CUH02), the Cambridge Trust and the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) (PhD scholarship to Dr Sortica da Costa/9418–11–3). FAZ is supported by the University of Manitoba Thorlakson Chair in Surgical Research Establishment Grant, University of Manitoba VPRI Research Investment Fund (RIF), Winnipeg Health Sciences Centre (HSC) Foundation and the University of Manitoba Rudy Falk Clinician-Scientist Professorship.
Competing interests The ICM+ software (ICM+; www.neurosurg.cam.ac.uk/icmplus) used for data monitoring and analysis is licensed by Cambridge Enterprise Limited (University of Cambridge). PS and MC have an interest in a fraction of the licensing fee.
Ethics approval The study was authorised by The Research and Development Department of Cambridge University Hospitals NHS Foundation Trust and approved by The East of England Research Ethics Committee (12/EE/0524).
Provenance and peer review Not commissioned; externally peer reviewed.
Patient consent for publication Not required.
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