Assessing key clinical parameters before and after intraventricular hemorrhage in very preterm infants

Hypercapnia Causes Injury of the Cerebral Cortex and Cognitive Deficits in Newborn Piglets

In critically ill newborns, exposure to hypercapnia (HC) is common and often accepted in neonatal intensive care units to prevent severe lung injury. However, as a "safe" range of arterial partial pressure of carbon dioxide levels in neonates has not been established, the potential impact of HC on the neurodevelopmental outcomes in these newborns remains a matter of concern. Here, in a newborn Yorkshire piglet model of either sex, we show that acute exposure to HC induced persistent cortical neuronal injury, associated cognitive and learning deficits, and long-term suppression of cortical electroencephalogram frequencies. HC induced a transient energy failure in cortical neurons, a persistent dysregulation of calcium-dependent proapoptotic signaling in the cerebral cortex, and activation of the apoptotic cascade, leading to nuclear deoxyribonucleic acid fragmentation. While neither 1 h of HC nor the rapid normalization of HC was associated with changes in cortical bioenergetics, rapid resuscitation resulted in a delayed onset of synaptosomal membrane lipid peroxidation, suggesting a dissociation between energy failure and the occurrence of synaptosomal lipid peroxidation. Even short durations of HC triggered biochemical responses at the subcellular level of the cortical neurons resulting in altered cortical activity and impaired neurobehavior. The deleterious effects of HC on the developing brain should be carefully considered as crucial elements of clinical decisions in the neonatal intensive care unit.

Machine learning predictive models for grading bronchopulmonary dysplasia: umbilical cord blood IL-6 as a biomarker

Objectives

This study aimed to analyze the predictive value of umbilical cord blood Interleukin-6 (UCB IL-6) for the severity-graded BPD and to establish machine learning (ML) predictive models in a Chinese population based on the 2019 NRN evidence-based guidelines.

Methods

In this retrospective analysis, we included infants born with gestational age <32 weeks, who underwent UCB IL-6 testing within 24 h of admission to our NICU between 2020 and 2022. We collected their medical information encompassing the maternal, perinatal, and early neonatal phases. Furthermore, we classified the grade of BPD according to the 2019 NRN evidence-based guidelines. The correlation between UCB IL-6 and the grades of BPD was analyzed. Univariate analysis and ordinal logistic regression were employed to identify risk factors, followed by the development of ML predictive models based on XGBoost, CatBoost, LightGBM, and Random Forest. The AUROC was used to evaluate the diagnostic value of each model. Besides, we generated feature importance distribution plots based on SHAP values to emphasize the significance of UCB IL-6 in the models.

Results

The study ultimately enrolled 414 preterm infants, with No BPD group (n = 309), Grade 1 BPD group (n = 73), and Grade 2-3 BPD group (n = 32). The levels of UCB IL-6 increased with the grades of BPD. UCB IL-6 demonstrated clinical significance in predicting various grades of BPD, particularly in distinguishing Grade 2-3 BPD patients, with an AUROC of 0.815 (95% CI: 0.753-0.877). All four ML models, XGBoost, CatBoost, LightGBM, and Random Forest, exhibited Micro-average AUROC values of 0.841, 0.870, 0.851, and 0.878, respectively. Notably, UCB IL-6 consistently appeared as the most prominent feature across the feature importance distribution plots in all four models.

Conclusion

UCB IL-6 significantly contributes to predicting severity-graded BPD, especially in grade 2-3 BPD. Through the development of four ML predictive models, we highlighted UCB IL-6's importance.

[Risk factors and prognosis of hypotension within 72 hours after birth in extremely preterm infants]

OBJECTIVES

To investigate the risk factors and prognosis of hypotension within 72 hours after birth in extremely preterm infants.

METHODS

A retrospective analysis was conducted on clinical data of extremely preterm infants admitted to the Children's Hospital of Zhejiang University School of Medicine from January 2019 to April 2022. Based on the presence of hypotension within 72 hours after birth, the eligible infants were divided into a hypotension group (41 cases) and a normotension group (82 cases). The clinical characteristics, echocardiographic parameters within 72 hours after birth, and early complications were compared between the two groups. Multivariate logistic regression analysis was used to explore the risk factors for hypotension within 72 hours after birth, and receiver operating characteristic curve analysis was performed to evaluate the predictive value of relevant indicators for the occurrence of hypotension within 72 hours after birth in the preterm infants.

RESULTS

The proportion of infants who required medication or surgical closure of patent ductus arteriosus (PDA), the proportions of infants with intraventricular hemorrhage ≥ grade III and severe pulmonary hemorrhage, and the mortality rate within 7 days in the hypotension group were significantly higher than those in the normotension group (P<0.05). Multivariate logistic regression analysis showed that lower birth weight, larger PDA diameter, and hemodynamically significant PDA were risk factors for the occurrence of hypotension within 72 hours after birth in extremely preterm infants (P<0.05). The receiver operating characteristic curve analysis showed that the combination of birth weight, PDA diameter, and hemodynamically significant PDA had an area under the curve of 0.873 (95%CI: 0.802-0.944, P<0.05) for predicting hypotension within 72 hours after birth, with a sensitivity of 73.2% and specificity of 91.5%.

CONCLUSIONS

Hypotension within 72 hours after birth is closely related to birth weight and PDA, and increases the risk of early severe complications and mortality in extremely preterm infants.

The role of blood pressure variability indicators combined with cerebral blood flow parameters in predicting intraventricular hemorrhage in very low birth weight preterm infants

Background

Hemodynamic instability is the main factor responsible for the development of intraventricular hemorrhage (IVH) in premature newborns. Herein, we evaluated the predictive ability of blood pressure variability (BPV) and anterior cerebral artery (ACA) blood flow parameters in IVH in premature infants with gestational age (GA) ≤32 weeks and birth weight (BW) ≤ 1,500 g.

Methods

Preterm infants with GA ≤32 weeks and BW ≤ 1,500 g admitted to the neonatal intensive care unit (NICU) of the hospital affiliated to Yangzhou University from January 2020 to January 2023 were selected as the research subjects. All preterm infants were admitted within 1 h after birth, and systolic blood pressure (SBP), diastolic blood pressure (DBP), and mean arterial blood pressure (MABP) were monitored at 1-h intervals. The difference between maximum and minimum values (max-min), standard deviation (SD), coefficient of variation (CV), and successive variation (SV) were used as BPV indicators. On the 1st, 3rd, and 7th day after birth, transcranial ultrasound examination was performed to screen for the occurrence of IVH. On the 24 ± 1 h after birth, systolic velocity (Vs), diastolic velocity (Vd), and resistance index (RI) of the ACA were measured simultaneously. Preterm infants were divided into the IVH group and non-IVH group based on the results of transcranial ultrasound examination, and the correlation between BPV indicators, ACA blood flow parameters, and development of IVH was analyzed.

Results

A total of 92 premature infants were enrolled, including 49 in the IVH group and 43 in the non-IVH group. There was no statistically significant difference in baseline characteristics such as BW, GA, sex, and perinatal medical history between the two groups of preterm infants (P > 0.05). The SBP SD (OR: 1.480, 95%CI: 1.020-2.147) and ACA-RI (OR: 3.027, 95%CI: 2.769-3.591) were independent risk factors for IVH in premature newborns. The sensitivity and specificity of combined detection of SBP SD and ACA-RI in predicting IVH were 61.2% and 79.1%, respectively.

Conclusion

High BPV and ACA-RI are related to IVH in premature infants with GA ≤32 w and BW ≤1,500 g. Combined detection of SBP SD and ACA-RI has a certain predictive effect on early identification of IVH.

Strong Association between Inotrope Administration and Intraventricular Hemorrhage, Gestational Age, and the Use of Fentanyl in Very Low Gestational Age Infants: A Retrospective Study

This was a single center, retrospective cohort study designed to evaluate the association between the administration of inotropes to hypotensive very low gestational age infants (VLGAI) and prenatal and neonatal risk factors. Inpatient medical records were reviewed to identify neonates treated with inotropes (treated group) and a control group for comparison. Two hundred and twenty two (222) VLGAI (less than 32 weeks' gestation) were included in the final analysis and were stratified based on timing of treatment with 83 infants (37.4%) and 139 infants (62.6%) in the treated and control groups, respectively. A total of 56/83 (67%) received inotropes for arterial hypotension during the first 3 days (early treatment subgroup) and 27/83 (32.5%) after 3 days of life (late-treated subgroup). Fentanyl, severe intraventricular hemorrhage (IVH), and gestational age (GA) were the risk factors most significantly associated with the need for inotrope use both during the first 3 days of life and the whole NICU stay, before and after adjustment for confounders. In conclusion, fentanyl, severe IVH, and GA are the risk factors most strongly associated with the need for inotrope treatment in VLGAI. Measures to modify these risk factors may decrease the need for cardiovascular medications and improve outcomes.

Reducing Severe Intraventricular Hemorrhage in Preterm Infants With Improved Care Bundle Adherence

BACKGROUND AND OBJECTIVES

Intraventricular hemorrhage prevention bundles (IVHPBs) can decrease the incidence of intraventricular hemorrhage (IVH) in premature infants. Our center had a high rate of severe (grade III/IV) IVH (9.8%), and poor adherence (24%) to an IVHPB in neonates born ≤1250 g or ≤30 gestational weeks. Improvement initiatives were planned to decrease the incidence of severe IVH by 30% over 2 years.

METHODS

A multidisciplinary team undertook interventions including in-service training, prompt initiation of IVHPB, revision of guidelines, and process standardization. Baseline data were collected from May 2016 to June 2018, with interventions occurring from July 2018 to May 2020. Adherence to the IVHPB was the primary process measure, and incidence of severe IVH the primary outcome measure. Control charts were used to analyze the effect of interventions on outcome. Balancing measures included use of breast milk at discharge, use of mechanical ventilation after initial resuscitation, and bronchopulmonary dysplasia.

RESULTS

A total of 240 infants were assessed preintervention, and 185 during interventions. Adherence to the IVHPB improved from 24% to 88%. During this period, the incidence of severe IVH decreased from 9.8% to 2.4%, a 76% reduction from baseline. A higher adherence score was associated with reduced odds of IVH (odds ratio 0.30; 95% confidence interval 0.10-0.90, P = .03).

CONCLUSIONS

Interventions focused on enhancing adherence to an IVHPB were associated with a reduced rate of severe IVH in high-risk neonates, highlighting the importance of assessing adherence to clinical guidelines.

Early Vital Sign Differences in Very Low Birth Weight Infants with Severe Intraventricular Hemorrhage

OBJECTIVE

Severe intraventricular hemorrhage (sIVH, grades 3 and 4) is a serious complication for very low birth weight (VLBW) infants and is often clinically silent requiring screening cranial ultrasound (cUS) for detection. Abnormal vital sign (VS) patterns might serve as biomarkers to identify risk or occurrence of sIVH.

STUDY DESIGN

This retrospective study was conducted in VLBW infants admitted to two level-IV neonatal intensive care units (NICUs) between January 2009 and December 2018. Inclusion criteria were: birth weight <1.5 kg and gestational age (GA) <32 weeks, at least 12 hours of systemic oxygen saturation from pulse oximetry (SpO2) data over the first 24 hours and cUS imaging. Infants were categorized as early sIVH (sIVH identified in the first 48 hours), late sIVH (sIVH identified after 48 hours and normal imaging in the first 48 hours), and no IVH. Infants with grades 1 and 2 or unknown timing IVH were excluded. Mean heart rate (HR), SpO2, mean arterial blood pressure (MABP), number of episodes of bradycardia (HR < 100 bpm), and desaturation (SpO2 < 80%) were compared.

RESULTS

A total of 639 infants (mean: 27 weeks' gestation) were included (567 no IVH, 34 early sIVH, and 37 late sIVH). In the first 48 hours, those with sIVH had significantly higher HR compared with those with no IVH. Infants with sIVH also had lower mean SpO2 and MABP and more desaturations <80%. No significant differences in VS patterns were identified in early versus late sIVH. Logistic regression identified higher HR and greater number of desaturations <80% as independently associated with sIVH.

CONCLUSION

VLBW infants who develop sIVH demonstrate VS differences with significantly lower SpO2 and higher mean HR over the first 48 hours after birth compared with VLBW infants with no IVH. Abnormalities in early VS patterns may be a useful biomarker for sIVH. Whether VS abnormalities predict or simply reflect sIVH remains to be determined.

KEY POINTS

· A higher HR in the first 48 hours is seen in infants with severe IVH.. · Infants with sIVH have lower blood pressure in the first 48 hours.. · Infants with sIVH have more oxygen desaturations in the first 48 hours..

Clinical Variables Associated With Grade III and IV Intraventricular Hemorrhage (IVH) in Preterm Infants Weighing Less Than 750 Grams

BACKGROUND

Despite innovative advances in neonatal medicine, intraventricular hemorrhage (IVH) continues to be a significant complication in neonatal intensive care units globally.

OBJECTIVE

The study aimed to discern the variables heightening the risk of severe IVH (Grade III and IV) in extremely premature infants weighing less than 750 grams. We postulated that a descending hematocrit (Hct) trend during the first week of life could serve as a predictive marker for the development of severe IVH in this vulnerable population.

METHODS

This retrospective case-control study encompassed infants weighing less than 750 grams at birth, diagnosed with Grade III and/or IV IVH, and born in a tertiary center from 2009 to 2014. A group of 17 infants with severe IVH was compared with 14 gestational age-matched controls. Acid-base status, glucose, fluid goal, urine output, and nutrient (caloric and protein) intake during the first four days of life were meticulously evaluated. Statistically significant variables from baseline data were further analyzed via univariable and multivariable logistic regression analyses, ensuring control for potential confounding variables.

RESULTS

The univariate logistic regression model delineated odds ratios (ORs) of 0.842 for day 2 average Hct (confidence interval [CI], 0.718-0.987) and 0.16 for urine output on day 3 (CI, 0.024-1.056), with the remaining six variables demonstrating no significant association. In the post-multivariable regression analysis, day 2 Hct was the only significant variable (OR, 0.731; 95% CI, 0.537-0.995; P=0.04). The receiver operating characteristic (ROC) curve analysis portrayed an area under the curve of 71% for the day 2 Hct variable.

CONCLUSION

The study revealed that a dip in Hct on day 2 of life augments the likelihood of Grade III and IV IVH among extremely premature infants with a birth weight of less than 750 grams. This insight amplifies our understanding of risk factors associated with severe IVH development in extremely preterm infants, potentially aiding in refining preventive strategies and optimizing clinical management and treatment of these affected infants.

Impact of concomitant necrotizing enterocolitis on mortality in very low birth weight infants with intraventricular hemorrhage

OBJECTIVE

To evaluate the impact of necrotizing enterocolitis (NEC) on mortality in very low birth weight (VLBW) infants with intraventricular hemorrhage (IVH).

STUDY DESIGN

Data were collected on VLBW infants born 2014-2018 at Vermont Oxford Network (VON) centers. NEC and IVH were categorized by severity. Adjusted risk ratios (ARR) for in-hospital mortality were calculated.

RESULTS

This study included 187 187 VLBW infants. Both medical and surgical NEC increased mortality risk compared to those without NEC. Stratification by IVH severity modified this effect (no IVH: ARR 3.04 (95%CI 2.74-3.38) for medical NEC and 4.17 (3.84-4.52) for surgical NEC; mild IVH: ARR 2.14 (1.88-2.44) for medical NEC and 2.49 (2.24-2.78) for surgical NEC; severe IVH: ARR 1.14 (1.03-1.26) for medical NEC and 1.10 (1.02-1.18) for surgical NEC).

CONCLUSION

The relative impact of NEC on mortality decreased as IVH severity increased. Given the frequent coexistence of NEC and IVH, these data inform multidisciplinary management of these complex patients.

Caffeine Restores Neuronal Damage and Inflammatory Response in a Model of Intraventricular Hemorrhage of the Preterm Newborn

Germinal matrix-intraventricular hemorrhage (GM-IVH) is the most frequent intracranial hemorrhage in the preterm infant (PT). Long-term GM-IVH-associated sequelae include cerebral palsy, sensory and motor impairment, learning disabilities, or neuropsychiatric disorders. The societal and health burden associated with GM-IVH is worsened by the fact that there is no successful treatment to limit or reduce brain damage and neurodevelopment disabilities. Caffeine (Caf) is a methylxanthine that binds to adenosine receptors, regularly used to treat the apnea of prematurity. While previous studies support the beneficial effects at the brain level of Caf in PT, there are no studies that specifically focus on the role of Caf in GM-IVH. Therefore, to further understand the role of Caf in GM-IVH, we have analyzed two doses of Caf (10 and 20 mg/kg) in a murine model of the disease. We have analyzed the short (P14) and long (P70) effects of the treatment on brain atrophy and neuron wellbeing, including density, curvature, and phospho-tau/total tau ratio. We have analyzed proliferation and neurogenesis, as well as microglia and hemorrhage burdens. We have also assessed the long-term effects of Caf treatment at cognitive level. To induce GM-IVH, we have administered intraventricular collagenase to P7 CD1 mice and have analyzed these animals in the short (P14) and long (P70) term. Caf showed a general neuroprotective effect in our model of GM-IVH of the PT. In our study, Caf administration diminishes brain atrophy and ventricle enlargement. Likewise, Caf limits neuronal damage, including neurite curvature and tau phosphorylation. It also contributes to maintaining neurogenesis in the subventricular zone, a neurogenic niche that is severely affected after GM-IVH. Furthermore, Caf ameliorates small vessel bleeding and inflammation in both the cortex and the subventricular zone. Observed mitigation of brain pathological features commonly associated with GM-IVH also results in a significant improvement of learning and memory abilities in the long term. Altogether, our data support the promising effects of Caf to reduce central nervous system complications associated with GM-IVH.

The Relationship Between Cord Blood Cytokine Levels and Perinatal Characteristics and Bronchopulmonary Dysplasia: A Case-Control Study

Objective

To establish the association between serial levels of inflammatory cytokines in cord blood and perinatal characteristics and bronchopulmonary dysplasia (BPD) in preterm infants.

Methods

147 premature infants with gestational age ≤32 weeks who were born and hospitalized in the First Affiliated Hospital of Zhengzhou University between July 2019 and August 2021 were enrolled in this retrospective case-control study. Multiple microsphere flow immunofluorescence was used to detect seven cytokines in cord blood collected within 24 h of birth. Demographics, delivery characteristics, maternal factors, neonatal characteristics, and clinical outcomes were collected for the two groups. An unconditional logistic regression model was used in this study to assess the clinical variables.

Results

IL-6 cord blood levels at birth were significantly higher in the BPD group than in the non-BPD group, but the odds ratio (OR) was very small (OR = 1). No differences in other cytokine concentrations were observed between the two groups. Multivariable logistic regression analysis demonstrated that increased maternal white blood cell (WBC) count on admission and lower birth weight increased the risk of BPD progression.

Conclusions

Increased IL-6 cord blood levels at birth in preterm infants may have trivial significance for predicting BPD. Furthermore, higher maternal WBC count on admission and lower birth weight increased the risk of BPD.

Accounting for arterial and capillary blood gases for calculation of cerebral blood flow in preterm infants

One of the most feared neurological complications of premature birth is intraventricular hemorrhage, frequently triggered by fluctuations in cerebral blood flow (CBF). Although several techniques for CBF measurement have been developed, they are not part of clinical routine in neonatal intensive care. A promising tool for monitoring of CBF is its numerical assessment using standard clinical parameters such as mean arterial pressure, carbon dioxide partial pressure (pCO₂) and oxygen partial pressure (pO₂). A standard blood gas analysis is performed on arterial blood. In neonates, capillary blood is widely used for analysis of blood gas parameters. The purpose of this study was the assessment of differences between arterial and capillary analysis of blood gases and adjustment of the mathematical model for CBF calculation to capillary values. The statistical analysis of pCO₂ and pO₂ values collected from 254 preterm infants with a gestational age of 23-30 weeks revealed no significant differences between arterial and capillary pCO₂ and significantly lower values for capillary pO₂. The estimated mean differences between arterial and capillary pO₂ of 15.15 mmHg (2.02 kPa) resulted in a significantly higher CBF calculated for capillary pO₂ compared to CBF calculated for arterial pO₂. Two methods for correction of capillary pO₂ were proposed and compared, one based on the mean difference and another one based on a regression model.

CONCLUSION

Capillary blood gas analysis with correction for pO₂ as proposed in the present work is an acceptable alternative to arterial sampling for the assessment of CBF.

WHAT IS KNOWN

• Arterial blood analysis is the gold standard in clinical practice. However, capillary blood is widely used for estimating blood gas parameters. • There is no significant difference between the arterial and capillary pCO₂ values, but the capillary pO₂ differs significantly from the arterial one.

WHAT IS NEW

• The lower capillary pO₂ values yield significantly higher values of calculated CBF compared to CBF computed from arterial pO₂ measurements. • Two correction methods for the adjustment of capillary pO₂ to arterial pO₂ that made the difference in the calculated CBF insignificant have been proposed.

Germinal Matrix-Intraventricular Hemorrhage of the Preterm Newborn and Preclinical Models: Inflammatory Considerations

The germinal matrix-intraventricular hemorrhage (GM-IVH) is one of the most important complications of the preterm newborn. Since these children are born at a critical time in brain development, they can develop short and long term neurological, sensory, cognitive and motor disabilities depending on the severity of the GM-IVH. In addition, hemorrhage triggers a microglia-mediated inflammatory response that damages the tissue adjacent to the injury. Nevertheless, a neuroprotective and neuroreparative role of the microglia has also been described, suggesting that neonatal microglia may have unique functions. While the implication of the inflammatory process in GM-IVH is well established, the difficulty to access a very delicate population has lead to the development of animal models that resemble the pathological features of GM-IVH. Genetically modified models and lesions induced by local administration of glycerol, collagenase or blood have been used to study associated inflammatory mechanisms as well as therapeutic targets. In the present study we review the GM-IVH complications, with special interest in inflammatory response and the role of microglia, both in patients and animal models, and we analyze specific proteins and cytokines that are currently under study as feasible predictors of GM-IVH evolution and prognosis.