Multiple Organ Dysfunction During Therapeutic Cooling of Asphyxiated Infants

Asphyxia, Therapeutic Hypothermia, and Pulmonary Hypertension

Neonates with a perinatal hypoxic insult and subsequent neonatal encephalopathy are at risk of acute pulmonary hypertension (aPH) in the transitional period. The phenotypic contributors to aPH following perinatal asphyxia include a combination of hypoxic vasoconstriction of the pulmonary vascular bed, right heart dysfunction, and left heart dysfunction. Therapeutic hypothermia is the standard of care for neonates with moderate-to-severe hypoxic ischemic encephalopathy. This review summarizes the underlying risk factors, causes of aPH in neonates with perinatal asphyxia, discusses the unique phenotypical contributors to disease, and explores the impact of the initial insult and subsequent therapeutic hypothermia on aPH.

Predictive performance of multiple organ dysfunction in asphyxiated newborns treated with therapeutic hypothermia on 24-month outcome: a cohort study

BACKGROUND

Perinatal asphyxia may be followed by multiple organ dysfunction (MOD) and is often included in prognostication of the individual patient, but evidence of discriminating accuracy is lacking. The aim of this study was to assess whether MOD in asphyxiated neonates during therapeutic hypothermia (TH) predicts mortality or neurodevelopmental impairment (NDI) at 24 months of age and which peripartum variables are associated with the onset of MOD.

METHODS

A retrospective analysis of a prospective cohort study of asphyxiated newborns undergoing TH was performed. MOD was defined as dysfunction of the brain (encephalopathy) combined with two or more organ systems. Outcome was routinely assessed by standardised developmental testing at the age of 24 months. The predictive accuracy of MOD on the combined outcome and its components (death and NDI) was expressed as areas under the receiver operating characteristic curves (AUROCs). The associations of peripartum variables and development of MOD were expressed as ORs and their CIs.

RESULTS

189 infants (median gestation 40 (range 36-42 weeks) with moderate to severe hypoxic ischaemic encephalopathy were included. 47% developed MOD. The prediction of the combined 24-month outcome or its components showed AUROCs <0.70. Associated with MOD were pH at birth (OR 0.97, CI 0.95 to 0.99), lactate at birth (OR 1.09, CI 1.04 to 1.15), Base Excess (BE) at birth (OR 0.94, CI 0.90 to 0.99) and epinephrine administration during resuscitation (OR 2.09, CI 1.02 to 4.40).

CONCLUSION

MOD has a low discriminating accuracy in predicting mortality or NDI at 24 months age and might not be useful for prognostication. Signs of acid-base disturbance and adrenalin use at birth are associated with the development of MOD.

Echocardiographic and ultrasound evaluation of haemodynamic parameters in hypoxic neonates treated with hypothermia: Study protocol

Background

Episodes of ischaemia-hypoxia in the perinatal period as well as the changes in the redistribution of blood may lead to decreased perfusion and ischaemia of the cardiac muscle. Additionally, there is a negative impact from the reduced contractility of the cardiac muscle secondary to acidosis and hypoxia. Therapeutic hypothermia (TH) improves the late effects in moderate and severe cases of hypoxia-ischaemia encephalopathy (HIE). The direct impact of TH on the cardiovascular system includes moderate bradycardia, increased pulmonary vascular resistance (PVR), inferior filling of the left ventricle (LV) and LV stroke volume. The above-mentioned consequences of TH and episodes of HI in the perinatal period are therefore exacerbation of respiratory and circulatory failure. The impact of the warming phase on the cardiovascular system is not well researched and currently few data has been published on this topic. Physiologically, warming increases heart rate, improves cardiac output and increases systemic pressure. The effect of TH and the warming phase on the cardiovascular values has a decisive impact on the metabolism of drugs, including vasopressors/inotropics, which in turn affects the choice of medication and fluid therapy.

Method

The study is a multi-centre, prospective, case-control, observational study. The study will include 100 neonates (50 subjects and 50 controls). Echocardiography and cerebral and abdominal ultrasound will be performed in the first 1/2 days after birth as well as during warming i.e., on day 4/7 of life. In neonatal controls these examinations will be performed for indications other than hypothermia, most frequently because of poor adaptation.

Ethics and dissemination

The Ethics Committee of the Medical University of Warsaw approved the study protocol prior to recruitment (KB 55/2021). Informed consent will be obtained from the carers of the neonates at the time of enrolment. Consent for participation in the study can be withdrawn at any time, without consequences and without obligation to justify the decision. All data will be stored in a secure, password-protected Excel file that is only accessible to researchers involved in the study. Findings will be published in a peer-reviewed journal and disseminated at relevant national and international conferences.

Clinical Trial Registration

NCT05574855.

Association between multi-organ dysfunction and adverse outcome in infants with hypoxic ischemic encephalopathy

OBJECTIVE

To evaluate multi-organ dysfunction (MOD) in newborns treated with therapeutic hypothermia (TH) for hypoxic ischemic encephalopathy (HIE), and to compare MOD in those with normal/mild magnetic resonance imaging (MRI) findings to those with moderate to severe MRI findings or death.

STUDY DESIGN

Retrospective single-center observational study of infants treated with TH. A total of 16 parameters across 7 organ systems were analyzed. Primary outcome was death or moderate to severe brain injury on MRI.

RESULT

Of 157 infants treated with TH, 77% had ≥2 organ systems with dysfunction. The number of organ systems with dysfunction was strongly associated with death or moderate-to-severe brain injury (p < 0.0001). Hematologic (68%) and hepatic (65%) dysfunction were most common. Neurologic and renal dysfunction were most strongly associated with the primary outcome (OR 13.5 [6.1-29.8] and 11.2 [4.1-30.3], respectively), while pulmonary hypertension was not.

CONCLUSION

MOD is prevalent in infants undergoing TH for HIE, and the association between MOD and adverse outcomes may impact clinical care and counseling.

Does Severity of Brain Injury on Magnetic Resonance Imaging Predict Short-Term Outcome in Neonates Who Received Therapeutic Hypothermia?

OBJECTIVE

 The National Institute of Child Health and Human Development (NICHD) magnetic resonance imaging (MRI) pattern of brain injury is a known biomarker of childhood outcome following therapeutic hypothermia for neonatal hypoxic-ischemic encephalopathy (HIE). However, usefulness of this classification has not been evaluated to predict short-term outcomes. The study aimed to test the hypothesis that infants with NICHD MRI pattern of severe hypoxic-ischemic brain injury will be sicker with more severe asphyxia-induced multiorgan dysfunction resulting in prolonged length of stay (LOS) following therapeutic hypothermia. We also evaluated the role of other risk factors which may prolong LOS.

STUDY DESIGN

 We retrospectively reviewed the medical records of 71 consecutively cooled neonates to examine the ability of MRI patterns of brain injury to predict the LOS. A neuroradiologist masked to outcomes classified the patterns of brain injury on MRI as per NICHD. Pattern 2A (basal ganglia thalamic, internal capsule, or watershed infarction), 2B (2A with cerebral lesions), and 3 (hemispheric devastation) of brain injury was deemed "severe injury."

RESULTS

 Out of 71 infants, 59 surviving infants had both MRI and LOS data. LOS was higher for infants who had Apgar's score of ≤5 at 10 minutes, severe HIE, seizures, coagulopathy, or needed vasopressors or inhaled nitric oxide, or had persistent feeding difficulty, or remained intubated following cooling. However, median LOS did not differ between the infants with and without MRI pattern of severe injury (15 days, interquartile range [IQR]: 9-28 vs. 12 days, IQR: 10-20; p = 0.4294). On multivariate linear regression analysis, only persistent feeding difficulty (β coefficient = 11, p = 0.001; or LOS = 11 days longer if had feeding difficulty) and ventilator days (β coefficient 1.7, p < 0.001; or LOS increased 1.7 times for each day of ventilator support) but not the severity of brain injury predicted LOS.

CONCLUSION

 Unlike neurodevelopmental outcome, LOS is not related to severity of brain injury as defined by the NICHD.

KEY POINTS

· The NICHD pattern of brain injury on MRI predicts neurodevelopmental outcome following hypothermia treatment for neonatal HIE.. · LOS did not differ between the infants with and without MRI patterns of severe injury.. · The severity of brain injury as defined by the NICHD was not predictive of the LOS following therapeutic hypothermia..

FIRS: Neonatal considerations

Fetal Inflammatory Response Syndrome (FIRS) is the fetal counterpart of systemic inflammatory response syndrome (SIRS) described in adults. When the fetus is directly exposed to inflammation of the fetal membranes or the placental-fetal circulation, and organs are adversely affected, the disorder is known as FIRS. This syndrome can significantly affect multiple organs with significant short and long term implications for the newborn. In cases of neonatal encephalopathy when no obvious etiology is identified, FIRS needs to be considered. Based on the significant incidence of chorioamnionitis and its potential effects on the newborn, any evidence of maternal, fetal, or neonatal infection should mandate further evaluation of the placenta and membrane histopathology.

Evaluation for the etiology of neonatal encephalopathy and the diagnosis of FIRS

A common disorder managed in the neonatal intensive care unit (NICU) is neonatal encephalopathy (NE). There are multiple causes of NE, including hypoxic-ischemic encephalopathy (HIE) and the fetal inflammatory response syndrome (FIRS). It is important to ascertain the specific cause of NE in an affected child, as it may affect the clinical management and will assist in prognostication. This paper discusses the background of inflammatory damage to the fetal brain, the history of FIRS as a clinical diagnosis, the characteristics of infants with FIRS, and methods to evaluate the etiology of NE.