Post-resuscitation strategies to avoid ongoing injury following intrapartum hypoxia-ischemia

Neonatal multiple organ failure after perinatal asphyxia

Perinatal asphyxia is an event with far-reaching consequences that can lead not only to the development of neonatal encephalopathy, but also to multiple organ failure (MOF). This ailment may result from the redistribution of blood flow, which would preserve the perfusion of vital organs such as the heart, brain and adrenal glands at the expense of other organs. The objective of the study was to determine the incidence and aetiopathogenesis of failure in the organs most frequently involved in neonatal MOF following perinatal asphyxia. We conducted a systematic literature search in the PubMed, Scopus and Cochrane Library databases using the MeSH terms (ischemia AND hypoxia AND multiorgan dysfunction AND neonat*), (asphyxia AND multiorgan dysfunction AND neonat*) and (liver/kidney/digestive OR gastrointestinal/heart injury AND ischemia AND hypoxia AND neonat*). We selected clinical and preclinical studies published after 2000 and excluded case series, letters to the editor, cohort studies without comparison groups and abstracts. In this study, we found that MOF associated with perinatal asphyxia is a frequent phenomenon with a relevant impact on neonatal morbidity and mortality, as it can cause changes not only in the kidney, liver and gastrointestinal tract, but also cardiomyopathy if the ailment is protracted or severe.

Positive fluid balance is associated with death and severity of brain injury in neonates with hypoxic-ischemic encephalopathy

OBJECTIVE

To investigate the association between fluid balance during therapeutic hypothermia (TH) and severity of brain injury on magnetic resonance imaging (MRI) in neonates with hypoxic-ischemic encephalopathy (HIE).

STUDY DESIGN

This is a secondary analysis of data from a prospective observational study in neonates with HIE. Daily net positive fluid balance during TH was investigated for association with the adverse primary outcome of death or moderate-to-severe brain injury on MRI using multivariable logistic regression.

RESULTS

Of the 150 neonates included, 50 suffered adverse outcome and had significantly higher net positive fluid balance (53 vs. 19 ml/kg/day, p < 0.01) during first 24 hours of TH. Neonates with a net positive fluid balance (>25 ml/kg/day) at 24 hours of TH had 3.4 (95% CI 1.3-9) times higher odds of adverse outcome.

CONCLUSIONS

Positive fluid balance during TH in neonates with HIE is independently associated with death or moderate-to-severe brain injury on MRI.

Subacute Hypoxia-Ischemia and the Timing of Injury in Treatment With Therapeutic Hypothermia

OBJECTIVE

This study aims to categorize infants treated with therapeutic hypothermia who presented with suspected subacute hypoxia-ischemia-that is, injury that likely occurred well before delivery and thus beyond the 6-hour window for therapeutic hypothermia-and to contrast the clinical characteristics with infants who suffered a known acute hypoxia-ischemia event.

DESIGN

A retrospective chart review was undertaken of infants treated with therapeutic hypothermia at our center during a 6-year period. Suspected subacute injury is defined as decreased fetal movement greater than 6 hours before delivery or severe depression at birth without need for cardiopulmonary resuscitation. Acute injury is defined as an acute perinatal event including placental abruption, ruptured uterus, or umbilical cord abnormalities. Abnormal outcome is defined as death, cognitive delay, or spastic quadriplegia at follow-up.

RESULTS

Infants with subacute (n = 7) versus acute injury (n = 26) were less likely to require cardiopulmonary resuscitation, were less acidotic at birth on cord gases with no significant difference in initial postnatal pH or base deficit, were more severely encephalopathic with severe amplitude electroencephalogram suppression, and demonstrated universal adverse outcome.

CONCLUSIONS

These data demonstrate greater benefit of therapeutic hypothermia for those infants with acute versus subacute injury. Early initiation of therapeutic hypothermia relative to the presumed onset of hypoxia-ischemia is critical. Early severe encephalopathy in the absence of a known acute perinatal event should raise concern in some cases for a subacute insult where the effect of therapeutic hypothermia is unlikely to be of benefit.

Minimal enteral nutrition during neonatal hypothermia treatment for perinatal hypoxic-ischaemic encephalopathy is safe and feasible

AIM

The safety and efficacy of enteral feeding during hypothermia treatment following hypoxic-ischaemic encephalopathy has not been studied before, resulting in variations in practice. Our study compared the benefits and safety of both early minimal and delayed enteral feeding during hypothermia treatment.

METHODS

Our retrospective cohort study, from January 2009 to December 2011, compared a Swedish cohort, who received early enteral feeding during hypothermia, and a UK cohort, who received delayed enteral feeding.

RESULTS

In Sweden (n = 51), enteral feeds were initiated at a median of 23.6 h and full oral feeding was achieved at 9 days (range 3-23). In the UK (n = 34), the equivalent figures were 100 h and 8 days (range 3-13) (p = 0.01). Both groups achieved enteral feeding at a median 6 days. The median length of hospital stay was 13 days in Sweden and 10 days in the UK (p = 0.04). More babies were fully breastfeeding or breastfed and bottle-fed at discharge in Sweden (85%) than the UK (67%) (p = 0.08). There were no significant differences between the two groups regarding adverse events.

CONCLUSION

Early minimal enteral feeding during hypothermia proved feasible, with no significant complications. Delayed enteral feeding did not affect time to full enteral feeding.

Early hyperglycemia is associated with poor gross motor outcome in asphyxiated term newborns

BACKGROUND

Hyperglycemia after ischemic stroke in adults and after near-drowning in children is associated with a poor neurological outcome. Anaerobic metabolism of glucose leads to buildup of lactic acid, free radical production, mitochondrial failure, and ultimately an increase in neurological injury. In asphyxiated infants, high lactate peaks are seen in the basal ganglia with magnetic resonance spectroscopy. Because motor disability in asphyxiated full-term newborns often relates to injury in the basal ganglia, we hypothesized that hyperglycemia and associated buildup of lactic acid may lead to worse gross motor outcome.

METHODS

Glucose, blood gas values, and demographic data were abstracted from the medical records of 41 term infants with asphyxia and without confounding diagnoses. Their Gross Motor Function Classification System scores were determined from the medical record or by structured telephone interviews.

RESULTS

The outcomes of 14 infants were considered poor on the basis of death within the first 6 months or moderate-to-severe cerebral palsy (Gross Motor Function Classification System score 1-5). The other 27 infants had no gross motor disability (Gross Motor Function Classification System score 0). The highest recorded blood glucose correlated with poor outcome (P = 0.046 by logistic regression). Infants with hyperglycemia (blood glucose > 150 mg/dL) were more likely to have poor outcome (P = 0.017; odds ratio: 5.9; 95% confidence interval: 1.4-24.7).

CONCLUSIONS

High blood glucose in the first 12 hours is associated with poor gross motor outcome in this cohort of asphyxiated term infants. Clinicians should avoid hyperglycemia in managing term infants with asphyxia.

Evaluation of Neonatal Hypoxic-Ischemic Encephalopathy by MRI and Ultrasound

Hypoxic-ischemic encephalopathy (HIE) is a major cause of brain damage and neurodevelopmental abnormalities in full-term newborn infants. We are reporting the results of a study comparing cranial magnetic resonance imaging (MRI) and cranial sonography (US) in 150 neonates with suspected HIE. Magnetic resonance imaging findings were normal in 44 patients (29%); 18% of patients showed only basal ganglia (BG) brightness, 10.6% showed brightness of the BG with intracerebral hemorrhage, and 63% of patients showed additional diagnostic details. Cranial US was normal in 75 patients (50%) and showed increased periventricular echogenicity in 32%, intraventricular hemorrhage in 9%, and additional diagnostic details in 13%. There was a positive correlation between MRI studies and US ( P = .013). These data suggest that US is a worthwhile modality for the diagnosis of HIE but that early MRI findings will provide additional information in many cases in the detection of cerebral intraventricular hemorrhage.

Cellular biology of end organ injury and strategies for prevention of injury

The interruption of placental blood flow induces circulatory responses to maintain cerebral, cardiac, and adrenal blood flow with reduced renal, hepatic, intestinal, and skin blood flow. If placental compromise is prolonged and/or severe, total circulatory failure is likely with cerebral hypoperfusion and resultant hypoxic ischemic cerebral injury with collateral renal, cardiac, and hepatic injury. Management strategies should be targeted at restoring cerebral perfusion and oxygen delivery and minimizing the extent of secondary injury. Specifically, the focus should include the judicious use of supplemental oxygen, avoidance of hypoglycemia and elevated temperature in the delivery room, and the early administration of therapeutic hypothermia to high-risk infants.

Granulocyte-colony stimulating factor in combination with stem cell factor confers greater neuroprotection after hypoxic-ischemic brain damage in the neonatal rats than a solitary treatment

Neonatal hypoxia-ischemia (HI) is a devastating condition resulting in neuronal cell death and often culminates in neurological deficits. Granulocyte-colony stimulating factor (G-CSF) has been shown to have neuroprotective activity via inhibition of apoptosis and inflammation in various stroke models. Stem cell factor (SCF) regulates hematopoietic stem cells in the bone marrow and has been reported to have neuroprotective properties in an experimental ischemic stroke model. In this study we aim to determine the protective effects of G-CSF in combination with SCF treatment after experimental HI. Seven-day old Sprague-Dawley rats were subjected to unilateral carotid artery ligation followed by 2.5 hours of hypoxia. Animals were randomly assigned to five groups: Sham (n=8), Vehicle (n=8), HI with G-CSF treatment (n=9), HI with SCF treatment (n=9) and HI with G-CSF+SCF treatment (coadministration group; n=10). G-CSF (50 µg/kg), SCF (50 µg/kg) and G-CSF+SCF (50 µg/kg) were administered intraperitoneally 1 hour post HI followed by daily injection for 4 consecutive days (five total injections). Animals were euthanized 14 days after HI for neurological testing. Additionally assessment of brain, heart, liver, spleen and kidney atrophy was performed. Both G-CSF and G-CSF+SCF treatments improved body growth and decreased brain atrophy at 14 days post HI. No significant differences were found in the peripheral organ weights between groups. Finally, the G-CSF+SCF coadministration group showed significant improvement in neurological function. Our data suggest that administration of G-CSF in combination with SCF not only prevented brain atrophy but also significantly improved neurological function.

Changing pattern of perinatal brain injury in term infants in recent years

Perinatal brain injury in term infants remains a significant clinical problem. Recently a change appears to have occurred in the pattern of such injuries. We sought to characterize the incidence, etiology, clinical manifestations, and outcomes of these injuries. A retrospective chart review identified clinical characteristics of neuroimaging, electroencephalography, and placental pathologic findings. Perinatal depression was defined as hypotonia and the need for respiratory support. From January 2004-December 2009, 29,597 term deliveries occurred. Brain injuries in 33 infants (live term births) included hypoxic-ischemic encephalopathy (n = 8; 0.27/1000), subdural hemorrhage (n = 10; 0.34/1000), intraventricular/intraparenchymal hemorrhage (n = 5; 0.17/1000), and focal cerebral infarctions (n = 4; 0.14/1000). Thirteen of 33 infants (39%) were triaged to a regular nursery. Delayed presentations included apnea (n = 6), desaturation episodes (n = 3), and seizures (n = 4). Twenty of 33 (61%) were admitted directly to the neonatal intensive care unit because of perinatal depression or evolving hypoxic-ischemic encephalopathy. Clinical signs included seizures (n = 12) and apnea (n = 2). Nine of 19 manifested electroencephalographic seizures. Pathology included chorioamnionitis (n = 7) and fetal thrombotic vasculopathy (n = 5). The latter was associated with focal cerebral infarctions in 3/4 cases. Most cases attributable to perinatal brain injury, except for evolving hypoxic-ischemic encephalopathy, are not identified according to any perinatal characteristics until the onset of signs, limiting opportunities for prevention.

A new neurological focus in neonatal intensive care

Advances in the care of high-risk newborn babies have contributed to reduced mortality rates for premature and term births, but the surviving neonates often have increased neurological morbidity. Therapies aimed at reducing the neurological sequelae of birth asphyxia at term have brought hypothermia treatment into the realm of standard care. However, this therapy does not provide complete protection from neurological complications and a need to develop adjunctive therapies for improved neurological outcomes remains. In addition, the care of neurologically impaired neonates, regardless of their gestational age, clearly requires a focused approach to avoid further injury to the brain and to optimize the neurodevelopmental status of the newborn baby at discharge from hospital. This focused approach includes, but is not limited to, monitoring of the patient's brain with amplitude-integrated and continuous video EEG, prevention of infection, developmentally appropriate care, and family support. Provision of dedicated neurocritical care to newborn babies requires a collaborative effort between neonatologists and neurologists, training in neonatal neurology for nurses and future generations of care providers, and the recognition that common neonatal medical problems and intensive care have an effect on the developing brain.

Long-term evaluation of granulocyte-colony stimulating factor on hypoxic-ischemic brain damage in infant rats

PURPOSE

Hypoxia-ischemia (HI), as a major cause of fetal brain damage, has long-lasting neurological implications. Therefore, therapeutic interventions that attenuate the neuropathological outcome of HI while also improving the neurofunctional outcome are of paramount clinical importance. The aim of this study was to investigate the long-term functional and protective actions of granulocyte-colony stimulating factor (G-CSF) treatment in an experimental model of cerebral HI.

METHODS

Postnatal day-7 Sprague-Dawley rats were subjected to HI surgery, which entailed ligation of the right common carotid artery followed by 2 h of hypoxia (8% O(2)). Treatment consisted of subcutaneous injection of G-CSF at 1 h after hypoxia followed by an additional one injection per day for 5 days (6 total injections) or for 10 days (11 total injections). Animals were euthanized 5 weeks post-insult for extensive evaluation of neurological deficits and assessment of brain, spleen, heart, and liver damage.

RESULTS

G-CSF treatment promoted somatic growth and prevented brain atrophy and underdevelopment of the heart. Moreover, reflexes, limb placing, muscle strength, motor coordination, short-term memory, and exploratory behavior were all significantly improved by both G-CSF dosing regimens.

CONCLUSIONS

Long-term neuroprotection afforded by G-CSF in both morphological and functional parameters after a hypoxic-ischemic event in the neonate provides a rationale for exploring clinical translation.

Changes in cerebral and visceral blood flow velocities in asphyxiated term neonates with hypoxic-ischemic encephalopathy

OBJECTIVE

The purpose of this study was to evaluate changes in the Doppler blood flow velocity (BFV) in the cerebral and visceral arteries in asphyxiated term neonates.

METHODS

The BFV was measured in 47 asphyxiated and 37 healthy term neonates in the anterior cerebral artery, middle cerebral artery, basilar artery, internal carotid artery, celiac artery (CA), superior mesenteric artery (SMA), and renal artery (RA) up to the age of 60 to 149 days.

RESULTS

At the age of 12 to 120 hours after asphyxia, the mean BFV had increased, and the resistive index (RI) had decreased (P < .05) in all cerebral arteries in neonates with severe hypoxic-ischemic encephalopathy (HIE) compared with the control group. In neonates with severe HIE, the mean BFV in the RA had significantly decreased at the age of 3 to 240 hours, and the RI had increased at the age of 24 to 240 hours, normalizing by the age of 21 to 59 days compared with the control group (P < .05). In the SMA, a decreased mean BFV was found in neonates with severe HIE compared with those with mild to moderate HIE only at the age of 24 to 36 hours. In neonates with mild to moderate HIE, the mean BFV had increased in the SMA and CA compared with the control group at the age of 2 to 11.9 hours.

CONCLUSIONS

A severe alteration of the cerebral and visceral BFV takes place during the first days after asphyxia in neonates with different severities of HIE.