Indices of hemodynamic and respiratory functions in premature infants at risk for the development of cerebral white matter injury

Early arterial pressure monitoring and term-equivalent age MRI findings in very preterm infants

INTRODUCTION

Variability of arterial blood pressure (ABP) has been associated with intraventricular hemorrhage in very preterm neonates (VPT) and may predict other brain lesions assessed at term-equivalent of age (TEA).

METHODS

This was a prospective single-center study including VPT with early invasive continuous ABP monitoring and assessed at TEA using brain magnetic resonance imaging (TEA-MRI). The association between early mean ABP (MABP) and TEA-MRI findings was modeled by multivariate logistic regression analysis using covariates selected by the LASSO method.

RESULTS

Among 99 VPT, the LASSO procedure selected consecutive periods of lowest MABP of 30 min on day 1 (d1) and 10 min on day 2 (d2) as the most relevant durations to predict TEA-MRI findings (OR [95% CI], 1.11 [1.02-1.23], p = 0.03 and 1.13 [1.01-1.27], p = 0.03, respectively). ROC curve analysis showed optimal thresholds at 30.25 mmHg on d1 and 33.25 mmHg on d2. This significant association persisted after adjustment with covariates including birthweight, gestational age, sex, and inotrope exposure. Final models selected by LASSO included the decile of the birthweight and lowest MABP for 30 min on d1 and 10 min on d2, for which the areas under the ROC curve were 74% and 75%, respectively.

CONCLUSION

Early continuous ABP monitoring may predict brain TEA-MRI findings in VPT.

IMPACT

Early arterial blood pressure monitoring may contribute to predicting brain damage upon MRI at term-equivalent of age for infants born very preterm. Careful blood pressure continuous monitoring in very preterm infants may identify infants at risk of long-term brain damage. Umbilical artery catheterization provides the best option for continuously monitoring arterial blood pressure in very preterm infants.

Risk Factors for Periventricular Leukomalacia in Preterm Infants: A Systematic Review, Meta-analysis, and GRADE-Based Assessment of Certainty of Evidence

BACKGROUND

We analyzed the certainty of evidence (CoE) for risk factors of periventricular leukomalacia (PVL) in preterm neonates, a common morbidity of prematurity.

METHODS

Medline, CENTRAL, Embase, and CINAHL were searched. Cohort and case-control studies and randomised randomized controlled trials were included. Data extraction was performed in duplicate. A random random-effects meta-analysis was utilizedused. CoE was evaluated as per Grading of Recommendations Assessment, Development and Evaluation (GRADE) guidelines.

RESULTS

One hundred eighty-six studies evaluating 95 risk factors for PVL were included. Of the 2,509,507 neonates assessed, 16,569 were diagnosed with PVL. Intraventricular hemorrhage [adjusted odds ratio: 3.22 (2.52-4.12)] had moderate CoE for its association with PVL. Other factors such as hypocarbia, chorioamnionitis, PPROM >48 hour, multifetal pregnancy reduction, antenatal indomethacin, lack of antenatal steroids, perinatal asphyxia, ventilation, shock/hypotension, patent ductus arteriosus requiring surgical ligation, late-onset circulatory collapse, sepsis, necrotizing enterocolitis, and neonatal surgery showed significant association with PVL after adjustment for confounders (CoE: very low to low). Amongst the risk factors associated with mother placental fetal (MPF) triad, there was paucity of literature related to genetic predisposition and defective placentation. Sensitivity analysis revealed that the strength of association between invasive ventilation and PVL decreased over time (P < 0.01), suggesting progress in ventilation strategies. Limited studies had evaluated diffuse PVL.

CONCLUSION

Despite decades of research, our findings indicate that the CoE is low to very low for most of the commonly attributed risk factors of PVL. Future studies should evaluate genetic predisposition and defective placentation in the MPF triad contributing to PVL. Studies evaluating exclusively diffuse PVL are warranted.

Chorioamnionitis in the pathogenesis of brain injury in preterm infants

Chorioamnionitis (or placental infection) is suspected to be a risk factor for brain injury in premature infants. The suggested association between chorioamnionitis and cystic periventricular leukomalacia and cerebral palsy is uncertain because of the variability of study designs and definitions of chorioamnionitis. Improvements in neonatal intensive care may have attenuated the impact of chorioamnionitis on brain health outcomes. Large multicenter studies using rigorous definitions of chorioamnionitis on placental pathologies and quantitative magnetic resonance techniques may offer the optimal way to clarify the complex role of chorioamnionitis in modifying brain health and long-term outcomes.

Atypical timing and presentation of periventricular haemorrhagic infarction in preterm infants: the role of thrombophilia

AIM

Periventricular haemorrhagic infarction (PVHI) is a complication of preterm birth associated with cardiorespiratory instability. To date, the role of thrombophilia as a possible additional risk factor in infants with atypical timing and presentation of PVHI has not been investigated.

METHOD

This was a retrospective cohort study of preterm infants who developed PVHI with an atypical timing and presentation either of antenatal onset or late in the postnatal course in the absence of a preceding sudden deterioration of their clinical condition. In infants with atypical PVHI mutation analysis of the factor V Leiden (G1691A), prothrombin (G20210A) gene, and C677T and A1298C polymorphisms in the MTHFR gene was performed, and plasma lipoprotein(a) and homocysteine levels were measured.

RESULTS

Sixty-two preterm infants who presented with a PVHI were studied. Seventeen had an atypical presentation (seven males, 10 females; median birthweight 1170g [range 580-1990g]; median gestational age 30.6wks [range 28.7-33.7wks]). The typical PVHI group comprised 28 males and 17 females (median birthweight 1200g [range 670-2210g]; median gestational age 29.6wks [range 25.3-33.6wks]). Among the 17 infants with atypical presentation, the factor V Leiden mutation was found in seven infants (41%) as well as in the mothers of six of these seven infants; in one infant this was concomitant with a prothrombin gene mutation. A polymorphism in the MTHFR gene was also present in these infants. In two infants with an atypical presentation who were tested for this, a mutation in the COL4A1 gene was found (reported previously). All but two of the infants with an atypical presentation developed spastic unilateral cerebral palsy.

INTERPRETATION

An atypical presentation of PVHI in preterm infants tends to occur more often in the presence of thrombophilia. Testing of thrombophilia, especially factor V Leiden and prothrombin gene mutation, is recommended in these infants.

Cerebellar hemorrhage in extremely low birth weight infants: incidence, risk factors, and impact on long-term outcomes

Improvements in neuroimaging technology and techniques have contributed to the increased recognition of cerebellar hemorrhage (CBH) in the prererm infant. Studies have indicated that the extremely low birth weight (ELBW) infant (< 1,000 g) is at highest risk for this injury. Associated risk factors include a constellation of antenaral, intrapartum, and neonatal factors, with immaturity, fetal distress, and cardiorespiratory instability in the early neonatal course as significant contributors. The long-term impact of CBH for the ELBW infant is not fully understood, but recent reports suggest that, in addition to motor impairments, deficits in cognitive, language, and social-behavioral function are also apparent. This article reviews the current state of knowledge of cerebellar development, risk factors for injury, and long-term developmental consequences of injury. Implications for nursing practice, education, and research are discussed.

Risk factors for adverse outcome in preterm infants with periventricular hemorrhagic infarction

OBJECTIVE

Our objective was to identify risk factors that were associated with mortality and adverse neurologic outcome at 18 months of age in preterm infants with periventricular hemorrhagic infarction.

METHODS

This was a retrospective cohort study of all preterm infants who were <37 weeks' gestation, had periventricular hemorrhagic infarction, and were admitted between 1995 and 2006. Ultrasound scans were reviewed for grading of germinal matrix hemorrhage, localization and extension of the infarction, and other abnormalities. Several clinical factors were scored. Outcome measures were mortality, cerebral palsy, and Gross Motor Function Classification System level. Odds ratios were calculated by univariate and multivariate logistic regression analyses.

RESULTS

Of 54 infants, 16 (30%) died. Twenty-five (66%) of 38 survivors developed cerebral palsy: 21 mild (Gross Motor Function Classification System levels 1 and 2) and 4 moderate to severe (levels 3 and 4). Several perinatal and neonatal risk factors were associated with mortality. After multivariate logistic regression, only use of inotropic drugs and maternal intrauterine infection were predictors of mortality. In survivors, only the most extended form of periventricular hemorrhagic infarction was associated with the development of cerebral palsy but not with severity of cerebral palsy. Cystic periventricular leukomalacia and concurrent grade 3 germinal matrix hemorrhage were associated with more severe cerebral palsy.

CONCLUSIONS

In preterm infants with periventricular hemorrhagic infarction, mortality occurred despite optimal treatment and was associated with circulatory failure and maternal intrauterine infection. In survivors, motor development was abnormal in 66%, but functional abilities were good in the majority. Extension and localization of the periventricular hemorrhagic infarction were not related to functional outcome.

Intrauterine Inflammation and the Onset of Peri-Intraventricular Hemorrhage in Premature Infants

BACKGROUND

Peri-intraventricular hemorrhage (P/IVH) is a common neonatal morbidity among premature infants. The aim of the study was to examine the association between placental and/or fetal inflammation and the onset of P/IVH in premature infants.

METHODS

A prospective study included 125 infants with gestational age 23-29 weeks. Placentas were examined for the presence of chorioamnionitis and funisitis, cord blood was sampled for the measurement of cytokines (IL-6 and IL-8). Fetal inflammation was defined as levels of IL-6 higher than 7.6 pg/ml. P/IVH was defined as early if diagnosed within the 1st day after birth; thereafter P/IVH was defined as late.

RESULTS

Adjusted for the influence of gestational age, early-onset sepsis (OR 3.2, p = 0.045) and no or incomplete antenatal steroid course (OR 6.0, p = 0.001) significantly predicted early P/IVH. Funisitis (OR 1.6, p = 0.06) and fetal inflammation (OR 2.6, p = 0.06) were only partially associated with early hemorrhage. Contrary to that, respiratory distress syndrome (OR 3.4, p = 0.04), mechanical ventilation (OR 5.9, p = 0.008), low blood pressure (OR 3.5, p = 0.02), and vasopressors (OR 5.7, p = 0.002) were associated with late P/IVH. In multivariate analysis no or incomplete steroid course remained independent predictors for early and use of vasopressors for late P/IVH. The interaction of fetal inflammation and vaginal delivery with no or incomplete steroid course increased the risk of early P/IVH.

CONCLUSIONS

These results indicate different risk factors for early and late P/IVH. Neither funisitis nor fetal inflammation independently predicts the onset of P/IVH. However, the interaction of fetal inflammation and vaginal delivery with no or incomplete antenatal steroid course increase the risk of early but not also late P/IVH.

Periventricular hemorrhagic infarction: risk factors and neonatal outcome

The aim of this study was to define the incidence, clinical associations, and short-term outcome of periventricular hemorrhagic infarction in the modern neonatal intensive care unit. From 5774 infants (birth weight<2500 gm), periventricular hemorrhagic infarction diagnosed by cranial ultrasound was identified and confirmed. gestational age-matched control infants were identified with normal cranial ultrasounds and detailed clinical data were obtained in both groups. Periventricular hemorrhagic infarction was confirmed in 58 infants. Incidence was 0.1% (1500-2500 gm), 2.2% (750-1500 gm), and 10% (<750 gm). Data across 6 study years reveal increased incidence in infants<750 gm. Compared with control infants, infants with periventricular hemorrhagic infarction had significantly greater association with assisted conception, intrapartum factors (emergency cesarean section, low Apgar scores), early neonatal complications (patent ductus arteriosus, pneumothorax, pulmonary hemorrhage), blood gas disturbances, and need for pressor, volume infusion, and respiratory support. Neonatal mortality of this group was 40% (n=23). Survivors had longer duration of mechanical ventilation and critical care stay compared with control subjects. Thirty-seven percent of survivors required cerebrospinal fluid shunt placement. Periventricular hemorrhagic infarction remains an important neurologic complication of prematurity. A growing population of survivors is apparent among infants with birth weight<750 gm. Multiple hemodynamic factors associated with periventricular hemorrhagic infarction cluster in the intrapartum and early neonatal periods.

Ultrasonographic features and severity scoring of periventricular hemorrhagic infarction in relation to risk factors and outcome

OBJECTIVE

Early diagnosis of periventricular hemorrhagic infarction in premature infants is based on bedside neonatal cranial ultrasonography. Currently, evaluation of its morphology and evolution by cranial ultrasound relies largely on data predating major advances in perinatal care and lacks a consistent classification system for determining severity of injury. The objective of this study was to examine the ultrasonographic morphology and evolution of periventricular hemorrhagic infarction in the modern NICU and to determine the value of a cranial ultrasonography-based severity score for predicting outcome.

METHODS

We retrospectively evaluated all cranial ultrasounds and medical records of 58 premature infants with periventricular hemorrhagic infarction. We assigned each subject a severity score based on extent of echodensity, unilateral versus bilateral, and presence or absence of midline shift. A neurologic examination was performed after 12 months adjusted age.

RESULTS

The parenchymal echodensity of periventricular hemorrhagic infarction most often involved parietal and frontal territories and evolved into single and/or multiple cysts. One quarter of cases were bilateral, and nearly 70% were extensive. Higher severity scores were significantly associated with pulmonary hemorrhage and low bicarbonate levels and with outcomes of fatality, early neonatal seizures, and motor disability.

CONCLUSIONS

Despite advances in perinatal medicine, periventricular hemorrhagic infarction remains an important complication of prematurity. Periventricular hemorrhagic infarction can be graded using a scoring system based on sonographic characteristics. Higher severity scores predict worse outcome. Such severity scoring could improve the clinician's ability to counsel parents regarding management decisions and early intervention strategies.

Inflammation in white matter: Clinical and pathophysiological aspects

While the central nervous system (CNS) is generally thought of as an immunopriviledged site, immune-mediated CNS white matter damage can occur in both the perinatal period and in adults, and can result in severe and persistent neurological deficits. Periventricular leukomalacia (PVL) is an inflammatory white matter disease of premature infants that frequently results in cerebral palsy (CP). Clinical and experimental studies show that both hypoxic/ischemic and innate immune mechanisms contribute to the destruction of immature oligodendroglia and of axons in the deep cerebral white matter in PVL. No data are yet available as to whether there is any genetic predisposition to PVL or to its neurological sequelae. Multiple sclerosis (MS) is an inflammatory white matter disease that often begins in young adulthood, causes multifocal destruction of mature oligodendroglia and of axons, and eventually leads to substantial cumulative neurological disability. Certain genetic polymorphisms contribute to susceptibility to MS, and adaptive immune responses to myelin-associated self antigens, or to exogenous antigens that mimic these self antigens, play a central role in the pathophysiology of this disease.

Cerebellar hemorrhage in the preterm infant: ultrasonographic findings and risk factors

Cerebellar hemorrhage (CBH) in premature infants is increasingly diagnosed secondary to improved neuroimaging techniques and survival of very small preterm infants. Information is limited, however, on the incidence, topography, and risk factors for CBH in the preterm infant.

OBJECTIVES

To define the incidence of CBH in preterm infants diagnosed by neonatal cranial ultrasound (US), describe the sonographic features of CBH, and identify maternal and perinatal risk factors associated with this lesion.

METHODS

A systematic electronic database search identified preterm infants born 1998-2002 with US diagnosis of CBH. For 35 cases of CBH we double-matched (according to gestational age, gender, and year of birth) 70 preterm controls with normal cranial USs and performed detailed medical-record reviews for both patients and controls.

RESULTS

Unilateral CBH was seen in 25 patients (71%), vermian hemorrhage was seen in 7 (20%), and combined bihemispheric and vermian hemorrhage was seen in 3 (9%). Isolated CBH occurred in 8 patients (23%); the remaining infants had associated supratentorial lesions. The incidence of CBH in preterm infants weighing <750 g at birth showed significant increase over the study period. Univariate analyses identified maternal, intrapartum, and early postnatal hemodynamic risk factors; multivariate regressions indicated that emergent caesarian section, patent ductus arteriosus, and lower 5-day minimum pH independently increased the odds of CBH. Neonatal mortality and morbidity were significantly higher among patients with CBH compared with preterm controls.

CONCLUSIONS

CBH is an important complication of extreme preterm birth and has been underrecognized in surviving preterm infants. Predictors of CBH seem to be multifactorial and include combined maternal, intrapartum, and early postnatal factors.

Effects of morphine analgesia in ventilated preterm neonates: primary outcomes from the NEOPAIN randomised trial

BACKGROUND

Opioid analgesia is commonly used during neonatal intensive care. We undertook the Neurologic Outcomes and Pre-emptive Analgesia in Neonates (NEOPAIN) trial to investigate whether pre-emptive morphine analgesia decreases the rate of a composite primary outcome of neonatal death, severe intraventricular haemorrhage (IVH), and periventricular leucomalacia (PVL) in preterm neonates.

METHODS

Ventilated preterm neonates (n=898) from 16 centres were randomly assigned masked placebo (n=449) or morphine (n=449) infusions. After a loading dose (100 microg/kg), morphine infusions (23-26 weeks of gestation 10 microg kg(-1) h(-1); 27-29 weeks 20 microg kg(-1) h(-1); 30-32 weeks 30 microg kg(-1) h(-1)) were continued as long as clinically justified (maximum 14 days). Open-label morphine could be given on clinical judgment (placebo group 242/443 [54.6%], morphine group 202/446 [45.3%]). Analyses were by intention to treat.

FINDINGS

Baseline variables were similar in the randomised groups. The placebo and morphine groups had similar rates of the composite outcome (105/408 [26%] vs 115/419 [27%]), neonatal death (47/449 [11%] vs 58/449 [13%]), severe IVH (46/429 [11%] vs 55/411 [13%]), and PVL (34/367 [9%] vs 27/367 [7%]). For neonates who were not given open-label morphine, rates of the composite outcome (53/225 [24%] vs 27/179 [15%], p=0.0338) and severe IVH (19/219 [9%] vs 6/189 [3%], p=0.0209) were higher in the morphine group than the placebo group. Placebo-group neonates receiving open-label morphine had worse rates of the composite outcome than those not receiving open-label morphine (78/228 [34%] vs 27/179 [15%], p<0.0001). Morphine-group neonates receiving open-label morphine were more likely to develop severe IVH (36/190 [19%] vs 19/219 [9%], p=0.0024).

INTERPRETATION

Pre-emptive morphine infusions did not reduce the frequency of severe IVH, PVL, or death in ventilated preterm neonates, but intermittent boluses of open-label morphine were associated with an increased rate of the composite outcome. The morphine doses used in this study decrease clinical signs of pain but can cause significant adverse effects in ventilated preterm neonates.