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The Diastolic Closing Margin Is Associated with Intraventricular Hemorrhage in Premature Infants
Christopher J Rhee1, Kathleen K Kibler2, R Blaine Easley2
1Department of Pediatrics, Section of Neonatology, Texas Children's Hospital/Baylor College of Medicine, 6621 Fannin Street, W6-104, Houston, TX, USA. cjrhee@texaschildrens.org.
Insights
Elevated diastolic closing margin (DCM), a measure of cerebral blood flow, is linked to severe intraventricular hemorrhage (IVH) in premature infants. This finding contrasts with the initial hypothesis of low DCM being associated with IVH.
Area of Science:
- Neonatal physiology
- Cerebral hemodynamics
- Perinatal medicine
Background:
- Premature infants face heightened risk of intraventricular hemorrhage (IVH).
- The precise roles of hypotension and hyperemia in IVH pathogenesis remain under investigation.
- Critical closing pressure (CrCP) and diastolic closing margin (DCM) are emerging metrics for cerebral perfusion assessment.
Purpose of the Study:
- To investigate the association between diastolic closing margin (DCM) and the incidence of severe intraventricular hemorrhage (IVH) in premature infants.
- To determine if a low DCM, hypothesized to be detrimental, is indeed a risk factor for IVH.
- To explore other hemodynamic factors associated with IVH in this vulnerable population.
Main Methods:
- Utilized umbilical artery catheters and transcranial Doppler to monitor cerebral blood flow velocity in 186 premature infants (GA 23-33 weeks) over the first week of life.
- Calculated critical closing pressure (CrCP) using both linear and impedance models.
- Employed multivariate generalized linear regression to analyze associations between DCM, hemodynamic parameters, and severe IVH (grades 3-4).
Main Results:
- An elevated DCM, irrespective of the calculation method (linear or impedance), was significantly associated with IVH (p < 0.0001 and p < 0.001, respectively).
- Lower 5-minute Apgar scores, increased mean cerebral blood flow velocity, and lower mean arterial blood pressure were also correlated with IVH (p < 0.0001).
- The study found that an elevated DCM, rather than a low DCM, was associated with severe IVH in the cohort.
Conclusions:
- Contrary to the initial hypothesis, an elevated diastolic closing margin (DCM) is associated with severe intraventricular hemorrhage (IVH) in premature infants.
- Hemodynamic factors including elevated mean cerebral blood flow velocity and lower mean arterial blood pressure are risk factors for IVH.
- These findings underscore the complexity of cerebral hemodynamics in premature infants and highlight the importance of monitoring parameters like DCM in preventing IVH.
Abstract:
Premature infants are at an increased risk of intraventricular hemorrhage (IVH). The roles of hypotension and hyperemia are still debated. Critical closing pressure (CrCP) is the arterial blood pressure (ABP) at which cerebral blood flow (CBF) ceases. When diastolic ABP is equal to CrCP, CBF occurs only during systole. The difference between diastolic ABP and CrCP is the diastolic closing margin (DCM). We hypothesized that a low DCM was associated with IVH. One hundred eighty-six premature infants, with a gestational age (GA) range of 23-33 weeks, were monitored with umbilical artery catheters and transcranial Doppler insonation of middle cerebral artery flow velocity for 1-h sessions over the first week of life. CrCP was calculated linearly and using an impedance model. A multivariate generalized linear regression model was used to determine associations with severe IVH (grades 3-4). An elevated DCM by either method was associated with IVH (p < 0.0001 for the linear method; p < 0.001 for the impedance model). Lower 5-min Apgar scores, elevated mean CBF velocity, and lower mean ABP were also associated with IVH (p < 0.0001). Elevated DCM, not low DCM, was associated with severe IVH in this cohort.
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