In the first report evaluating the impact of a clinical guideline that calls for the use of postoperative continuous electroencephalography (CEEG) on infants after they’ve had cardiopulmonary bypass surgery, investigators at Children’s Hospital of Philadelphia and the University of Pennsylvania validated the clinical utility of routine CEEG monitoring and found that clinical assessment for seizures without CEEG is not a reliable marker for diagnosis and treatment.
In a report online in the Journal of Thoracic and Cardiovascular Surgery (J. Thorac. Cardiovasc. Surg. 2015 [doi:10.1016/j.jtcvs.2015.03.045]), Dr. Maryam Naim and colleagues said that CEEG identified electroencephalographic seizures in 8% of newborns after cardiopulmonary bypass surgery. The study, conducted over 18 months, evaluated 172 newborns, none older than 1 month, with 161 (94%) having undergone postoperative CEEG. They had CEEG within 6 hours of their return to the cardiac intensive care unit.
Courtesy of JTCVS/AATS
Newborns had CEEG within 6 hours of their return to the cardiac intensive care unit.
The study classified electroencephalographic seizures as EEG-only (also termed nonconvulsive seizures, with no observable clinical signs either at bedside or via video) or electroclinical seizures. Dr. Naim and colleagues said the majority of seizures they identified with CEEG would not have been noticed otherwise as they had no clinically obvious signs or symptoms.
The American Clinical Neurophysiology Society (ACNS) recommends that cardiac surgeons consider continuous CEEG monitoring in high-risk neonates with congenital heart disease (CHD) after bypass surgery, but Dr. Naim and coauthors raised the question of whether seizure incidence would justify routine CEEG for all neonates with CHD who’ve had bypass surgery, especially as health systems place greater emphasis on quality improvement programs and cost-effective strategies. The authors said that neonates with all types of congenital heart disease had seizures.
“In adult populations, CEEG has not been shown to significantly increase hospital costs, but cost-effectiveness analyses have not been performed in neonates with CHD,” the authors said.
So they attempted to identify at-risk populations of newborns who would benefit most from routine CEEG monitoring. In a multivariable model that the investigators used, both delayed sternal closure and longer deep hypothermic circulatory arrest (DHCA) during surgery seemed predictive of seizures, but the odds ratios for both were low, “suggesting the statistically significant findings may not be very useful in focusing CEEG implementation on a high-risk group.”
Previous studies have reported that identifying and treating seizures in newborns who have had bypass surgery may reduce secondary brain injury and improve outcomes (Pediatrics 2008;121:e759-67), and the Boston Circulatory Arrest Study showed an association between postoperative seizures and lower reading and math scores and lower cognitive and functional skills later in life (Circulation 2011;124:1361-1369). The authors cited other studies that showed older, critically ill children with “high seizure burdens” have had worse outcomes. (Critical Care Medicine 2013;31:215-23; Neurology 2014;82:396-404; Brain 2014;137:1429-38). They also pointed out increased risk if the seizure is not treated. “While occurrence of a seizure is a marker of brain injury, there may also be secondary injury if the seizure activity is not terminated,” Dr. Naim and coauthors said.
The investigators concluded that postoperative CEEG to identify seizures “is warranted,” and while they found some newborns may be at greater risk of postbypass seizures than others, they advocated for “widespread” monitoring strategies.
Their work also questioned the effectiveness of non-CEEG assessment. In the study, clinicians identified bedside events indicative of seizures – what the study termed “push-button events” – in 32 newborns, or about 18% of patients, but none of the events had an EEG correlate, so they were considered nonepileptic. When the authors looked more closely at those “push-button” events, they found they ranged from abnormal body movement in 14 and hypertension in 7 to tachycardia and abnormal face movements, among other characterizations, in lesser numbers.
“Furthermore, push-button events by bedside clinicians, including abnormal movements and hypertensive episodes concerning for possible seizures, did not have any EEG correlate, indicating that bedside clinical assessment for seizures without CEEG monitoring is unreliable,” Dr. Naim and colleagues said.
As to whether identifying and treating postbypass seizures in young newborns with CHD will improve long-term neurodevelopment in these children, the authors acknowledged that further study is needed.
They reported having no financial disclosures.