Background Cerebral AR is a complex, developmentally regulated process still not well characterised in neonates. A number of factors interact with the smooth muscle cells regulating cerebral arterial tone and perfusion. Various analytical methods have been applied to explore AR¹. Although in this multifactorial process the assessment of synchronicity and causality is crucial, yet it has not been established.

Objective To analyse the temporal causality between two biological signals in the frequency-domain by quantifying the influence of each signal to the other across the frequencies. To assess the predictive capacity of the method to classify infants at risk for adverse neonatal outcome.

Methods Partial directed coherence (PDC)² and spectral coherence (COH) methods were used to analyse the relationship between spontaneous changes in mean arterial blood pressure (MABP) and near-infrared cerebral oximetry (TOI). PDC_MABP»TOI indicated that changes in TOI were induced by MABP changes and PDC_TOI»MABP, the opposite.

Results PDC_MABP»TOI and PDC_TOI»MABP values differed. PDC_MABP»TOI and COH predicted low superior vena cava (SVC) flow (≤41 ml/kg per min) with an area under the ROC curve of 0.68 (95% CI: 0.63–0.77; p < 0.001) and 0.60 (95% CI: 0.51–0.70; p < 0.05), respectively; whereas PDC_TOI»MABP did not (p < 0.248). The pPDC_MABP»TOI and pCOH were calculated as the averaged value per patient. pPDC_MABP»TOI but not pCOH predicted mortality.

Conclusions PDC_MABP»TOI is a good classifier for infants at risk of brain hypoperfusion and adverse outcome. PDC_MABP»TOI allows a non-invasive physiological interpretation of the pressure-AR process in neonates.

References

1. Riera J et al. 2014 (submitted)

2. Baccalá L, Sameshima K. Biol_Cyber 2001.