Abstract
Background: Impaired cerebral autoregulation is a key pathogenic factor in preterm cerebral injury, but the association of blood pressure variability (BPV) with autoregulatory impairment is unknown. We hypothesized that increased BPV in sick preterm infants leads to cerebral autoregulatory impairment. Using spectral analysis, we aimed to determine autoregulatory capacity in the early postnatal period, assessed by the correlation between mean arterial blood pressure (MABP, mmHg) and cerebral oxygenation (tissue oxygenation index, TOI %), and its relation with BPV(mmHg2)
Method: Twenty-seven preterm infants of mean gestational age of 26.3 (± 1.3) weeks were studied on the first 3 postnatal days. TOI was continuously measured by Spatially Resolved Spectroscopy (Hamamatsu NIRO 200) together with MABP from an arterial catheter. Spectral coherence analysis was used to assess concordance between MABP and TOI, expressed as Coherence score (Coh) with a value of >0.5 suggesting impaired autoregulation. BPV was assessed using power spectral density of MABP.
Results: In the frequency range 0.003-0.02Hz, BPV and maximum Coh showed a significant correlation (p=0.03). The median (IQR) minimum BPV associated with Coh >0.5 was lower in the very sick infants with Clinical Risk Index for Babies (CRIB) score of >7, compared with infants with CRIB score < 7 [29.7 (24.7-76.9) vs 99.7 (79.6 - 208.4) mmHg2, p=0.03]
Conclusions: Cerebral autoregulatory impairment is associated with increased BPV, though this occurs with a comparatively lower level of BPV in extremely sick preterm infants. Our findings suggest that the sickest preterm infants are more vulnerable to cerebral injury from BPV.
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Silas, R., Hew, S., Walker, A. et al. 92 Impaired Cerebral Autoregulation is Associated with Increased Blood Pressure Variability in Preterm Infants. Pediatr Res 68 (Suppl 1), 49 (2010). https://doi.org/10.1203/00006450-201011001-00092
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DOI: https://doi.org/10.1203/00006450-201011001-00092
