Fluctuating pressure-passivity is common in the cerebral circulation of sick premature infants

Area of Science:

• Neonatology
• Cerebrovascular Physiology
• Medical Engineering

Background:

• Cerebral blood flow pressure-passivity impairs autoregulation, potentially causing cerebrovascular injury in premature infants.
• Transient pressure-passivity events were previously observed but difficult to detect reliably with static measurements.
• Continuous monitoring is needed to accurately assess cerebral pressure-passivity in neonates.

Purpose of the Study:

• To detect and quantify cerebral pressure-passivity in the first 5 days of life in premature infants (<1500 g birth weight).
• To investigate the prevalence and influencing factors of cerebral pressure-passivity using continuous monitoring.

Main Methods:

• Continuous bedside recordings of mean arterial pressure (MAP) and cerebral perfusion via near-infrared spectroscopy (NIRS) Hb difference (HbD) signal.
• Defined pressure-passivity using coherence between MAP and HbD signals.
• Calculated a pressure-passive index (PPI) based on the percentage of 10-min epochs with significant low-frequency coherence.

Main Results:

• Pressure-passivity was highly prevalent, occurring in 87 of 90 premature infants, with a mean PPI of 20.3%.
• Significant associations were found between pressure-passivity and lower gestational age, lower birth weight, and systemic hypotension.
• Maternal hemodynamic factors were associated with pressure-passivity, but maternal infection markers were not.

Conclusions:

• Cerebral pressure-passivity is a common finding in the early postnatal period for very low birth weight infants.
• Continuous monitoring effectively detects pressure-passivity, which is linked to prematurity and hemodynamic instability.
• Further research correlating the pressure-passive index with serial brain imaging is necessary to understand its impact on cerebrovascular injury.