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Journal of Biomedical Optics • Open Access

Precision of coherence analysis to detect cerebral autoregulation by near-infrared spectroscopy in preterm infants
Author(s): Gitte Holst Hahn; Karl Bang Christensen; Terence S. Leung; Gorm Greisen

Paper 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 (variabilityABP) improves precision. We examined the impact of variabilityABP 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 variabilityABP within the power spectrum did not improve the precision. However, adjusting for the variabilityABP among repeated measurements (i.e., weighting measurements with high variabilityABP 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 variabilityABP between repeated measurements.

Paper Details

Date Published: 1 May 2010
PDF: 10 pages
J. Biomed. Opt. 15(3) 037002 doi: 10.1117/1.3426323
Published in: Journal of Biomedical Optics Volume 15, Issue 3
Show Author Affiliations
Gitte Holst Hahn, Copenhagen Univ. Hospital Rigshopitalet (Denmark)
Karl Bang Christensen, Univ. of Copenhagen (Denmark)
Terence S. Leung, Univ. College London (United Kingdom)
Gorm Greisen, Copenhagen Univ. Hospital Rigshopitalet (Denmark)

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