Precision of coherence analysis to detect cerebral autoregulation by near-infrared spectroscopy in preterm infants

Gitte Holst Hahn; Karl Bang Christensen; Terence S. Leung; Gorm Greisen

doi:10.1117/1.3426323

1 May 2010 Precision of coherence analysis to detect cerebral autoregulation by near-infrared spectroscopy in preterm infants

Gitte Holst Hahn; Karl Bang Christensen; Terence S. Leung; Gorm Greisen;

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J. of Biomedical Optics, 15(3), 037002 (2010). doi:10.1117/1.3426323

Abstract

Coherence between spontaneous fluctuations in arterial blood pressure (ABP) and the cerebral near-infrared spectroscopy signal can detect cerebral autoregulation. Because reliable measurement depends on signals with high signal-to-noise ratio, we hypothesized that coherence is more precisely determined when fluctuations in ABP are large rather than small. Therefore, we investigated whether adjusting for variability in ABP (variability_ABP) improves precision. We examined the impact of variability_ABP within the power spectrum in each measurement and between repeated measurements in preterm infants. We also examined total monitoring time required to discriminate among infants with a simulation study. We studied 22 preterm infants (GA<30) yielding 215 10-min measurements. Surprisingly, adjusting for variability_ABP within the power spectrum did not improve the precision. However, adjusting for the variability_ABP among repeated measurements (i.e., weighting measurements with high variability_ABP in favor of those with low) improved the precision. The evidence of drift in individual infants was weak. Minimum monitoring time needed to discriminate among infants was 1.3-3.7 h. Coherence analysis in low frequencies (0.04-0.1 Hz) had higher precision and statistically more power than in very low frequencies (0.003-0.04 Hz). In conclusion, a reliable detection of cerebral autoregulation takes hours and the precision is improved by adjusting for variability_ABP between repeated measurements.

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Gitte Holst Hahn, Karl Bang Christensen, Terence S. Leung, Gorm Greisen, "Precision of coherence analysis to detect cerebral autoregulation by near-infrared spectroscopy in preterm infants," Journal of Biomedical Optics 15(3), 037002 (1 May 2010). http://dx.doi.org/10.1117/1.3426323

Submission: Received ; Accepted

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