“Therapeutic Hypothermia: Treatment of Hypoxic Ischemic Encephalopathy Part 1” by Denise Casey

[Music] you there are pewter hypothermia treatment of hypoxic ischemic encephalopathy part one by denise Casey hello my name is Denise Casey and I’m a clinical nurse specialist in the neonatal intensive care unit at Boston Children’s Hospital I’m going to be talking with you today about hypoxic ischemic encephalopathy commonly referred to as hie overview hie is defined as an interruption of supply of oxygen hypoxia and our blood flow ischemia going to the brain and body this kind of interruption can happen for a number of reasons such as compression of the placenta tearing of the placenta from the uterine wall or compression of the cord hie occurs in one in every thousand term live births and remains an important cause of mortality and neurodevelopmental deficits and infants pathophysiology now I’m going to be talking with you about the pathophysiology of hie the brain is approximately 2% of body mass but consumes 15% of energy generated the brain has minimal energy stores and thus depends on a second supply of oxygen and glucose by the blood hae is characterized as a biphasic process the initial phase is referred to as the primary brain energy failure in the secondary phase is referred to as a secondary energy failure the primary brain energy failure phase there is a drop in cerebral perfusion which leads to hypoxia and at this time the infant is found to be hypoglycemic an anemic due to the energy crisis this further results in metabolic acidosis ischemia and cell death leading to neurologic dysfunction during the energy crisis the body experiences intracellular arrangements these derangements lead to an increase in intracellular calcium thus causing edema and cell death in this phase of injury there is continued destruction of proteins membrane lipids and other cellular contents which lead to neuronal necrosis which can be found hours to days later in the secondary energy failure phase this typically occurs six to 12 hours after the initial insult if untreated this leads to sustained brain injury during the space of injury there’s inflammation apoptosis oxidative injury due prease growth factors and protein synthesis which are affected hie not only affects the brain but can have multi-system involvement as well such as respiratory depression cardiac dysfunction pulmonary hypertension requiring assisted ventilation renal impairment typically these patients present with oliguria initially and then during recovery a high output tubular failure they can also have electrolyte arrangements in hepatic impairment such as di C now that we have reviewed the pathophysiology of hae I would like to describe how hie is commonly classified classification hie is commonly classified according to the saranac grading scale I will focus on the moderate to severe encephalopathy classifications as this is what we are targeting for the treatment with therapeutic hypothermia moderate encephalopathy runs a 10 percent risk of death and 30 percent risk of disability these patients typically present lethargic with reduced tone of the extremities diminish brainstem reflexes and possible clinical seizures severe encephalopathy carries a 60% risk of death and many if not all who survive demonstrate neurodevelopmental disabilities including intellectual sensory and motor impairments resulting from brain injury typically these patients present in a coma they have weaker absent respiratory drive no response to stimuli placid tone of the extremities and trunk diminished or absent brainstem reflexes diminished tendon reflexes in an EEG that is severely abnormal now that I have spoken about the classifications of hie I will now focus on the inclusion exclusion and extended criteria for treatment with this therapy therapeutic hypothermia studies have shown that therapeutic hypothermia has neuroprotective effects if Institute prior to the secondary energy failure phase thus decreasing the severity of brain injury therapeutic hypothermia reduces cerebral metabolism decreases the rate of cell death and delays a cascade of metabolic changes that occur with hie our original guidelines and inclusion exclusion criteria were adapted from the landmark studies completed back in 2005 as evidence has emerged from clinical trials we have modified our protocols to incorporate the latest information we have a multi facility neuroprotection group that meets regularly and rigorously discusses new evidence and shared clinical practice here at BCH we use a following inclusion criteria there are three distinct criteria that need to be met such as age and weight greater than 36 weeks and greater than or equal to Chi kilos evidence of perinatal distress which can be seen in the field period or postnatal II and neonatal encephalopathy examples of perinatal distress in the fetal period include abruption cord prolapse examples of perinatal distress in the newborn period include a low Apgar score poor post natal blood gas and continued need for ventilation neonatal encephalopathy is determined by a neurology exam it may include altered level of consciousness and seizures in addition you can use a amplitude EEG monitor to help guide this decision and assess electrical activity of the brain over the last two years as new evidence has emerged we have expanded our inclusion criteria for each of these criteria we’ll evaluate on a case-by-case basis to determine the risk benefit ratio of the therapy there is evolving evidence with these criteria and you will have to determine the applicability at your institution a few examples are infants between the ages of 34 to 36 weeks you should consider but need to take into account other factors that may put them at higher risk of adverse effects related at the hypothermia an age greater than six hours possibly extending this window up to 12 hours when initiating treatment in acute fetal maternal hemorrhage this may or may not present with perinatal asphyxia so consider a neuro exam and eg to assess eligibility even if the patient does not meet the inclusion criteria as well as consider infants that suffer a postnatal collapse such as near SIDS as this is a postnatal etiology of hie the exclusion criteria for this therapy is a normal EEG for these patients we would consider continued monitoring to assess for potential later decline in neurologic condition and monitor the patient for a minimum of 24 hours before transfer or discharged to home the inability to cool by 6 hours patient should be cooled as soon as possible and ideally within 6 hours following the hypoxic ischemic insult however providing hypothermia between 6 to 12 hours post insult should be considered and evaluated on a case-by-case basis any chromosomal or genetic anomalies such as trisomy 13 or 18 a systemic infection such as symptomatic systemic congenital viral or bacterial infection coagulopathy such as low platelet counts evidence of clinical bleeding or spontaneous clinical bleeding in a major intracranial hemorrhage knowledge gained the AAP Committee on fetus and newborn published a clinical report in 2014 on the knowledge gained thus far and what uncertainties still remain with the treatment of therapeutic hypothermia thus far there have been twelve hundred infants enrolled in six large clinical trials analysis showed that moderate hypothermia was a modestly effective neural rescue strategy in the moderate to severe encephalopathy classifications there is uncertainty that still remains due to the little variability and trials such as the Deaf thunderation of cooling cooling infants less than 35 weeks as well as cooling those prior to transfer since the incidence of death and disability remains high after cooling we need to seek out further therapies to improve the outcomes of infants with hie they are promising neuroprotective agents such as erythropoietin anti epileptic drugs melatonin xenon and topiramate as adjunctive therapy to therapeutic hypothermia that are currently underway in research studies we need to continue to follow up on neurodevelopmental outcomes at later time intervals thank you for watching this video on therapeutic hypothermia for the treatment of hie please help us improve the content by providing us with some feedback you


  1. Please subscribe to my page and watch my videos, I am trying to bring more awareness to babies with HIE and have started a page to do so I would love to hear what people would want to see as content and bring hope for families with loved ones who suffer from HIE as a whole. Thanks in advance

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