Cardiovascular Supportive Therapies for Neonates With Asphyxia - A Literature Review of Pre-clinical and Clinical Studies

Impact of persistent pulmonary hypertension and oxygenation on brain injury in neonates with neonatal encephalopathy treated with therapeutic hypothermia

OBJECTIVE

To investigate the effects of persistent pulmonary hypertension (PPHN) and oxygenation on outcome of neonates with neonatal encephalopathy (NE) treated with therapeutic hypothermia (TH).

STUDY DESIGN

We compared the outcome of neonates with NE treated with TH with or without PPHN.

RESULTS

384 neonates with NE were treated with TH; 24% had PPHN. The fraction of inspired oxygen was higher in the first 4 days of life (p < 0.001) in neonates with PPHN. They had a significantly lower arterial partial pressure of oxygen in the first 4 days of life (p = 0.005) and higher on days 3-4 of life (p < 0.001). They were more often intubated (p < 0.001) and more often had concomitant hypotension (p < 0.001). They had higher mortality (p = 0.009) and more often developed brain injury (p = 0.02).

CONCLUSION

PPHN occurred frequently in neonates with NE treated with TH and was associated with a higher incidence of adverse outcome.

Myocardial Work for Dynamic Monitoring of Myocardial Injury in Neonatal Asphyxia

To assess the value of parameters of myocardial work for dynamic monitoring of myocardial injury after neonatal asphyxia. Fifty-three neonates with asphyxia admitted within 24 h after delivery were divided into a mild asphyxia group (n = 40) and severe asphyxia group (n = 13). Echocardiography was performed within 24 h post-birth, within 72 h post-birth (48 h after first echo), and during recovery. The left ventricular ejection fraction on M-mode echocardiography and by Simpson's biplane method (LVEF and Bi-EF, respectively), stroke volume (SV), cardiac output (CO), cardiac index (CI), global longitudinal strain (GLS), global work index (GWI), global constructive work (GCW), and other parameters were measured. Echocardiographic indicators were compared between groups and over time. GWI was significantly increased at 72 h in the mild asphyxia group (P < 0.05) but showed no significant change over time in the severe asphyxia group (P > 0.05). While GCW increased significantly over time in both groups (P < 0.05), it increased earlier in the mild asphyxia group. Time and grouping factors had independent effects on GWI and GCW (P > 0.05). The characteristics of differences in GWI and GCW between the two groups were different from those for LVEF, Bi-EF, SV, CO, CI, and GLS and their change characteristics with improvement from treatment. GWI and GCW changed significantly during recovery from neonatal asphyxia, and their change characteristics differed between mild and severe asphyxia cases. Myocardial work parameters can be used as valuable supplements to traditional indicators of left ventricular function to dynamically monitor the recovery from myocardial injury after neonatal asphyxia.

Use of Vasopressors in Extremely Preterm Infants in First Week of Life

OBJECTIVE

 A significant variability exists for diagnosis and treatment of hypotension in extremely preterm infants. Benefits of the use of vasopressors remain unclear. We wanted to identify the risk factors associated with use of vasopressors in the first week of life and their impact on outcomes of extremely preterm infants.

STUDY DESIGN

 Retrospective review of all newborns ≤28 weeks of gestational age (GA) admitted in neonatal intensive care unit from October 1, 2012, to October 31, 2015, done. Data regarding antenatal and neonatal characteristics and outcomes were recorded. Study infants were divided into two cohorts and compared based on vasopressor use. Chi-square, t-test, and multiple logistic regression were performed as appropriate and significance set at p <0.05.

RESULTS

 Of 213 extremely preterm infants, 90 (42.3%) received vasopressors in first week of life. The mean arterial pressure (MAP) at admission in these infants was significantly lower than that of infants who did not require vasopressors (27 ± 8 vs. 30 ± 6 mm Hg, p < 0.05). Vasopressors were initiated within 24 hours in 91% of babies. After controlling for other variables, use of vasopressors was significantly higher in infants with lower birth weight (odds ratio [OR]: 3.2, 95% confidence interval [CI]: 1.6-8.3), 5-minute Apgar's score ≤5 (OR: 1.8, 95% CI: 1.2-3.12), and admission hypothermia (OR: 2.7, 95% CI: 1.3-4.9). The use of vasopressors was significantly associated with severe intraventricular hemorrhage (IVH), even after controlling for other significant variables (OR: 5.9, 95% CI: 1.6-9.3).

CONCLUSION

 Lower birth weight, low 5-minute Apgar's score, and admission hypothermia are characteristics associated with early use of vasopressors in extremely preterm infants. Infants treated with vasopressors are at a higher risk of developing severe IVH.

KEY POINTS

· Low systemic blood pressure is a very common problem in the extremely preterm population.. · In clinical practice, mean arterial blood pressure (BP) less than the infants GA in week is typically considered to be "low BP.". · About 50% of infants born at <29 weeks of GA received very preterm in the first week of life.. · Use of vasopressors is associated with a higher incidence of intraventricular hemorrhage in extremely preterm population..

Low Apgar score and asphyxia complications at birth and risk of longer-term cardiovascular disease: a nationwide population-based study of term infants

Background

Most follow-up studies have focused on the long-term consequences of asphyxia at birth on the brain. The aim of this study was to investigate associations between low Apgar score and asphyxia-related complications and subsequent risks of cardiovascular diseases (CVD) in childhood and early adulthood.

Methods

This population-based cohort study included 2,826,424 non-malformed singleton births, born at term (≥37 weeks' gestation) between 1988 and 2018 in Sweden. Primary exposure was a composite of asphyxia-related complications, defined as a) Apgar score 0-3 at 1-min; or b) Apgar score 0-3 at 5-min; or c) neonatal seizures (including hypoxic ischemic encephalopathy). Using Cox regression, we estimated the risk of CVD after 1 year of age, defined as stroke, coronary heart disease, heart failure, and atrial fibrillation.

Results

Overall, there were 4165 cases with cardiovascular diseases. Individuals with asphyxia-related complications had adjusted hazard ratios (95% confidence intervals) of 1.90 (1.54 to 2.34) for cardiovascular disease, 2.29 (1.74 to 3.03) for stroke, 2.17 (1.37 to 3.42) for heart failure, and 1.38 (0.87 to 2.17) for atrial fibrillation. Hazard ratios for CVD were elevated among individuals with Apgar score 0-3 at 1 and 5 min, and those with neonatal seizures. Compared with unexposed individuals, neonatal seizures were associated with 5 times higher rates of stroke and heart failure, respectively.

Interpretation

Asphyxia-related complications and its neonatal complications, especially low Apgar score and neonatal seizures, are associated with increased risks of CVD in childhood and early adulthood, although the absolute risk of CVD is low in young age.

Funding

Swedish Research Council and the Swedish Heart-Lung Foundation.

Systematic Review and Meta-Analysis of Cardiovascular Medications in Neonatal Hypotension

Background

Comparative studies among the various cardiovascular medications used for the treatment of neonatal hypotension are lacking.

Methods

This systematic review and pairwise meta-analysis of the anti-hypotensive treatments in preterm and term infants was conducted to evaluate efficacy and impact on outcome. Electronic databases were searched up to February 2021 for relevant articles. As an extension of the current approach for study selection, a machine learning technique was used. Only randomized controlled trials (RCTs) of inotropes, pressors, volume therapy, and corticosteroids were included. Response to treatment was the primary outcome while secondary outcomes included mortality and common morbidities.

Results

Nineteen RCTs involving 758 preterm and term neonates were found, and 8 treatments were evaluated. Most studies involved subjects with early hypotension associated with prematurity. Pairwise meta-analysis among treatments showed that dopamine was more effective than dobutamine regarding the response to treatment (restoration of normotension or normalization of blood pressure) (7 trials, 286 neonates, odds ratio, 3.06 [95% CI = 1.06–8.87]; I² = 49%, very low quality of the evidence per GRADE). Comparisons of other treatments were not significant. No differences were found among regimens regarding survival and other secondary outcomes.

Conclusion

In this systematic review and pairwise meta-analysis, only the comparison of dopamine versus dobutamine provided evidence for efficacy of treatment and favored dopamine. No safe conclusions could be reached in regard to other treatments. Data regarding the management of arterial hypotension in conditions other than transition after birth in preterm newborns are sparse both in preterm and term infants.

Misoprostol treatment prevents hypoxia-induced cardiac dysfunction through a 14-3-3 and PKA regulatory motif on Bnip3

Systemic hypoxia is a common element in most perinatal emergencies and is a known driver of Bnip3 expression in the neonatal heart. Bnip3 plays a prominent role in the evolution of necrotic cell death, disrupting ER calcium homeostasis and initiating mitochondrial permeability transition (MPT). Emerging evidence suggests a cardioprotective role for the prostaglandin E1 analog misoprostol during periods of hypoxia, but the mechanisms for this protection are not completely understood. Using a combination of mouse and cell models, we tested if misoprostol is cardioprotective during neonatal hypoxic injury by altering Bnip3 function. Here we report that hypoxia elicits mitochondrial-fragmentation, MPT, reduced ejection fraction, and evidence of necroinflammation, which were abrogated with misoprostol treatment or Bnip3 knockout. Through molecular studies we show that misoprostol leads to PKA-dependent Bnip3 phosphorylation at threonine-181, and subsequent redistribution of Bnip3 from mitochondrial Opa1 and the ER through an interaction with 14-3-3 proteins. Taken together, our results demonstrate a role for Bnip3 phosphorylation in the regulation of cardiomyocyte contractile/metabolic dysfunction, and necroinflammation. Furthermore, we identify a potential pharmacological mechanism to prevent neonatal hypoxic injury.

Hemodynamic response to milrinone for refractory hypoxemia during therapeutic hypothermia for neonatal hypoxic ischemic encephalopathy

OBJECTIVE

Characterize the impact of milrinone on arterial pressure of neonates with persistent hypoxemic respiratory failure (HRF) and hypoxic ischemic encephalopathy (HIE) treated with inhaled nitric oxide and therapeutic hypothermia (TH).

STUDY DESIGN

Retrospective cohort study. Arterial pressure was assessed hourly for 24 h. The primary outcome was change in diastolic arterial pressure (DAP).

RESULTS

56 patients were included [(i) cases: HIE/TH who received milrinone (n = 9), (ii) Milrinone controls (n = 17), (iii) HIE controls (n = 30)]. Baseline demographics, severity of HRF and arterial pressure were comparable between groups. Only milrinone treated patients with HIE/TH had a marked drop in DAP in the first hour, which persisted for more than 12 h despite escalation in inotropes (p = 0.008).

CONCLUSION

Milrinone treated patients with HRF and HIE/TH develop profound reduction in DAP and require escalation of cardiovascular support. The risk benefit profile of milrinone should be considered and pharmacological studies are warranted to evaluate drug metabolism and clearance in this population.

Hemodynamic optimization for neonates with neonatal encephalopathy caused by a hypoxic ischemic event: Physiological and therapeutic considerations

Neonatal encephalopathy due to a hypoxic-ischemic event is commonly associated with cardiac dysfunction and acute pulmonary hypertension; both therapeutic hypothermia and rewarming modify loading conditions and blood flow. The pathophysiological contributors to disease are complex with a high degree of clinical overlap and traditional bedside measures used to assess circulatory adequacy have multiple confounders. Comprehensive, quantitative echocardiography may be used to delineate the relative contribution of lung parenchymal, pulmonary vascular, and cardiac disease to hypotension and/or hypoxemic respiratory failure. In this review, we provide a detailed overview of the contributors to hemodynamic instability following perinatal hypoxic-ischemic injury. Our proposed approach to therapy focuses on physiopathological considerations with interventions individualized to this potentially complex condition and considers the pharmacological idiosyncrasies, which may occur among neonates with NE presenting with multiorgan dysfunction while undergoing therapeutic hypothermia.

Optimizing hemodynamic care in neonatal encephalopathy

Hemodynamic impairment occurs in up to 80% of infants with neonatal encephalopathy (NE). Not all infants benefit from therapeutic hypothermia (HT); there are some indications that the trajectory of brain injury might be modified by neurologic monitoring and early management over the first 72-h period. It is also possible that optimizing hemodynamic management may further improve outomes. The coupling between cerebral blood flow and cerebral metabolism is disrupted in NE, increasing the vulnerability of the newborn brain to secondary injury. Hemodynamic monitoring is usually limited to blood pressure and functional echocardiographic measurements, which may not accurately reflect brain perfusion. This review explores the evidence base for hemodynamic assessment and management of infants with NE while undergoing HT. We discuss the literature behind a systematic approach to a baby with NE with the aim to define best therapies to optimize brain perfusion and reduce secondary injury.

Management of Neonatal Hypotension and Shock

The current standard approach to manage circulatory insufficiency is inappropriately simple and clear: respond to low blood pressure to achieve higher values. However, the evidence for this is limited affecting all steps within the process: assessment, decision making, therapeutic options, and treatment effects. We have to overcome the 'one size fits all' approach and respect the dynamic physiologic transition from fetal to neonatal life in the context of complex underlying conditions. Caregivers need to individualize their approaches to individual circumstances. This paper will review various clinical scenarios, including managing transitional low blood pressure, to circulatory impairment involving different pathologies such as hypoxia-ischemia and sepsis. We will highlight the current evidence and set potential goals for future development in these areas. We hope to encourage caregivers to question the current standards and to support urgently needed research in this overlooked but crucial field of neonatal intensive care.

Hypothermia and Cardiovascular Instability

Severely asphyxiated neonates have acute heart failure as part of their multiorgan dysfunction syndrome during the first days of life. Supporting the cardiovascular system during this phase is part of contemporary treatment and regarded as vital for limiting the neurodevelopmental injury. The decision to treat cardiovascular instability should be based on evaluation of end-organ function. Neonatologist-performed echocardiography in combination with other diagnostic modalities enables comprehensive real-time assessment. This review discusses associations between hemodynamics and adverse outcome, modalities for evaluating the hemodynamic state of the infant, and therapeutic approaches during intensive care.

Getting an Early Start in Understanding Perinatal Asphyxia Impact on the Cardiovascular System

Perinatal asphyxia (PA) is a burdening pathology with high short-term mortality and severe long-term consequences. Its incidence, reaching as high as 10 cases per 1000 live births in the less developed countries, prompts the need for better awareness and prevention of cases at risk, together with management by easily applicable protocols. PA acts first and foremost on the nervous tissue, but also on the heart, by hypoxia and subsequent ischemia-reperfusion injury. Myocardial development at birth is still incomplete and cannot adequately respond to this aggression. Cardiac dysfunction, including low ventricular output, bradycardia, and pulmonary hypertension, complicates the already compromised circulatory status of the newborn with PA. Multiorgan and especially cardiovascular failure seem to play a crucial role in the secondary phase of hypoxic-ischemic encephalopathy (HIE) and its high mortality rate. Hypothermia is an acceptable solution for HIE, but there is a fragile equilibrium between therapeutic gain and cardiovascular instability. A profound understanding of the underlying mechanisms of the nervous and cardiovascular systems and a close collaboration between the bench and bedside specialists in these domains is compulsory. More resources need to be directed toward the prevention of PA and the consecutive decrease of cardiovascular dysfunction. Not much can be done in case of an unexpected acute event that produces PA, where recognition and prompt delivery are the key factors for a positive clinical result. However, the situation is different for high-risk pregnancies or circumstances that make the fetus more vulnerable to asphyxia. Improving the outcome in these cases is possible through careful monitoring, identifying the high-risk pregnancies, and the implementation of novel prenatal strategies. Also, apart from adequately supporting the heart through the acute episode, there is a need for protocols for long-term cardiovascular follow-up. This will increase our recognition of any lasting myocardial damage and will enhance our perspective on the real impact of PA. The goal of this article is to review data on the cardiovascular consequences of PA, in the context of an immature cardiovascular system, discuss the potential contribution of cardiovascular impairment on short and long-term outcomes, and propose further directions of research in this field.