Hypoxic ischemic encephalopathy : diagnosis, hypothermia treatment and outcome

Abstract

Hypothermia treatment (HT) is now proven to be neuroprotective, is associated with favourable outcomes, and is considered as the standard of care for moderate to severe hypoxic ischemic encephalopathy (HIE). The treatment should be regionalized with a minimum of ten treated infants per year with regard to securing patient safety, staff training, development and future research. Still, many infants are in desperate need of additional therapies for neuronal rescue to reduce the risk of death or severe handicap. The implementation of a national HT register has revealed differences in the regional incidence of HT, indicating that infants that could benefit from HT do not receive this therapy.

All of the following main findings in this thesis have lead to changes in clinical practice:

* Prevention of HIE by using fetal scalp blood lactate combined with fetal heart rate/cardiotocogram during labour is feasible. We consider fetal scalp blood lactate measurement at the cut-off level at of 4.8 mmol/L (75th percentile) to be a better predictive marker for hypoxia-ischemia during labour than pH. The predictive capacity is higher and the sampling technique is easier, with a high success rate.

* Early induction of HT is feasible prior to transport. Earlier start of HT could mean that the neuroprotective effect is more beneficial. However, passive cooling results in a high risk of excessive cooling and should be used with caution, i.e. temperature should be monitored continuously and personnel should be trained in HT induction at all delivery units.

* Moderate HT alters the predictive value of amplitude integrated EEG (aEEG) in asphyxiated infants. These findings are of central value in the context of early prognosis and in decision making for withdrawal or continuation of intensive care treatment.

* The overwhelming majority of infants with moderate neonatal encephalopathy (NE) have major and/or cognitive disabilities at long-term follow-up. Most children with cerebral paresis (CP) also have cognitive dysfunctions. This is of great importance for early therapeutic interventions, allocation of habilitation resources and support for the educational system.

In conclusion our findings gives an additional diagnostic tool in prevention of HIE, gives important information on implementation of hypothermia treatment and emphasis the necessity of long-term follow-up in encephalopatic infants.