Critical Closing Pressure by Diffuse Correlation Spectroscopy in a Neonatal Piglet Model

Area of Science:

• Neonatal physiology
• Cerebrovascular autoregulation
• Biomedical engineering

Background:

• Critical closing pressure (CrCP) is the arterial blood pressure (ABP) at which cerebral blood flow (CBF) ceases.
• Preterm infants have low ABP near their CrCP, leading to diastolic no-flow, making CrCP estimation clinically significant.
• Transcranial Doppler (TCD) ultrasound is a current method for estimating CrCP in preterm infants.

Purpose of the Study:

• To compare and validate the critical closing pressure (CrCP) measured by diffuse correlation spectroscopy (DCS) against TCD ultrasound.
• To assess the feasibility of DCS for continuous, noninvasive measurement of microvascular CBF in a neonatal setting.

Main Methods:

• Hemorrhagic shock was induced in 13 neonatal piglets.
• Cerebral blood flow (CBF) was continuously measured using both DCS and TCD ultrasound.
• CrCP was calculated using a cerebrovascular impedance model.

Main Results:

• CrCP measurements by DCS and TCD ultrasound demonstrated good correlation (median r² = 0.8).
• Bland-Altman analysis revealed a median bias of -3.5 between the two modalities.
• This study represents the first comparison of DCS and TCD for CrCP in a neonatal piglet hemorrhagic shock model.

Conclusions:

• DCS shows promise as a validated method for estimating critical closing pressure (CrCP) in neonates.
• Observed differences in CrCP may stem from microvascular versus macrovascular vasomotor tone variations.
• Further research is warranted to understand the implications of these differences in clinical practice.