Real-time monitoring of wavelet-based neurovascular coupling in neonates with hypoxic ischemic encephalopathy using...

Real-time monitoring of neurovascular coupling (NVC) is crucial for early diagnosis and effective treatment strategies in neonates with hypoxic ischemic encephalopathy (HIE). In our previous studies, the NVC of neonates with HIE was determined using wavelet transform coherence (WTC) between the amplitude-integrated electroencephalogram (aEEG) and regional cerebral oxygen saturation ( ${\mathrm{SctO}}_2$ ) using a post-acquisition analysis.

We propose a time-resolved WTC analysis, providing a real-time analysis tool that facilitates immediate and continuous evaluation of cerebral hemodynamics and neuronal activity.

The real-time WTC framework employs a progressive zero-padding strategy with incremental temporal data integration. Initial analysis preserves 4 h of $\mathrm{aEEG}/{\mathrm{SctO}}_2$ data while zero-padding 16 h to maintain a 20-h window. This enables calculation of time-resolved significant coherence (trSC) at time 2 h (1- to 2-h window) within the 20- to 150-min scale range. The system subsequently advances hourly, preserving an additional hour of acquired data while proportionally reducing zero-padding. This cascading approach continues until full 20-h data preservation, with final trSC calculations targeting time 18 h (17- to 18-h window).

We included 55 neonates with mild to severe HIE, the time-scale maps of which were obtained using both post-acquisition and real-time WTC analysis methods. Accordingly, trSC curves within the 20- to 150-min wavelet scale were statistically compared between the two methods using a linear mixed-effects model. There was no significant difference in trSC results between the two methods ( $p=0.159$ ). In addition, NVC was significantly lower in the moderate to severe HIE group compared with the mild HIE group at hours 3 and 4 ( $p<0.01$ ).

We demonstrated the feasibility of real-time dynamic WTC analysis for dynamic NVC in newborns with HIE, providing a potential bedside tool for the early detection of brain abnormalities.