Electroencephalographic Changes after Pediatric Cardiac Surgery with Cardiopulmonary Bypass: Is Slow Wave Activity Unfavorable?

Abstract

Pediatric cardiac surgery with cardiopulmonary bypass (CPB) is frequently associated with neurologic deficits. We describe the postoperative EEG changes, assess their possible causes, and evaluate their relevance to neurologic outcome. Thirty-one children and five neonates with congenital heart disease were included. EEG recording started after intubation and continued until 22-96 h after CPB. In addition to conventional analysis, spectral analysis was performed for occipital and frontal electrodes, and differences between pre-and postoperative delta power (delta-␦P) were calculated. Maximum values of occipital delta-␦P that occurred within 48 h after CPB were correlated with clinical variables and with perioperative markers of oxidative stress and inflammation. Occipital delta-␦P correlated with frontal delta-␦P, and maximum delta-␦P correlated with conventional rating. Distinct rise of ␦P was detected in 18 of 21 children without any acute or long-term neurologic deficits but only in five of 10 children with temporary or permanent neurologic deficits. Furthermore, maximally registered delta-␦P was inversely associated with duration of CPB and postoperative ventilation. Maximal delta-␦P was also inversely associated with the loss of plasma ascorbate (as an index of oxidative stress) and plasma levels of IL-6 and IL-8. Slow wave activity frequently occurs within 48 h after CPB. However, our data do not support the notion that EEG slowing is associated with adverse neurologic outcome. This is supported by the fact that EEG slowing was associated with less oxido-inflammatory stress. Abbreviations AC, aortic cross-clamping CPB, cardiopulmonary bypass FFT, fast Fourier transformation max delta-␦P, maximum difference between pre-and postoperative delta power MDA, malondialdehyde MDA-TNL, malondialdehyde corrected for total neutral lipids ␦P, delta power delta-␦P, difference between pre-and postoperative delta power Cardiac surgery with cardiopulmonary bypass (CPB) in children and neonates is frequently associated with acute neurologic symptoms and long-term neurologic deficits (1-4). Neuropsychological deficits persist in a substantial number of patients. During the intraoperative period, a global decrease in perfusion and oxygen delivery and focal ischemia related to embolic insults or diffuse microvascular changes are the principal mechanisms of brain damage (5). Systemic inflammation and reactive oxygen species generated by CPB might contribute to postoperative neurologic dysfunction (6,7). Impaired cerebral vasoregulation and ischemia/reperfusion injury continues in the early postoperative period (8,9). Postoperative cardiopulmonary dysfunction may additionally threaten cerebral perfusion pressure and oxygen delivery. However, there is an increased energy demand to restore neuronal membrane function and ionic gradients that are compromised by CPB.Events that affect the brain are usually followed by neuronal dysfunction, which can often be detected by EEG changes.

A Review of Long-term EEG Monitoring in Critically Ill Children With Hypoxic–Ischemic Encephalopathy, Congenital Heart Disease, ECMO, and Stroke

“…NCS may be even more common than convulsions in patients with congenital heart disease (Helmers, Wypij, Constantinou, et al 1997, Gaynor, et al 2005, Clancy, et al 2005, Chock, et al 2006, Schmitt, et al 2005, Gunn, et al 2012). In the D-transposition of the great arteries study mentioned above, 136 of 171 infants underwent cEEG for 48 hours, and electrographic seizures occurred in 20%.…”

Electroencephalographic Monitoring in the Pediatric Intensive Care Unit

“…[53] A study of children who underwent cardiac surgery with cardiopulmonary bypass and underwent EEG from intubation until 22–96 hours after bypass reported ES in 8% of 36. [54] Finally, a study of 39 infants undergoing Norwood-type operations and continuous amplitude-integrated EEG identified intraoperative seizures in 23% and postoperative seizures in 18%. [55] Risk factors for seizures in children with congenital heart disease include co-existing genetic defects, aortic arch obstruction, the presence of a ventricular septal defect, treatment with deep hypothermic circulatory arrest rather than continuous cardiopulmonary bypass and prolonged deep hypothermic circulatory arrest.…”

Neurocognitive Monitoring and Care During Pediatric Cardiopulmonary Bypass — Current and Future Directions

“…Schmitt et al reported alarmingly high rates of postoperative acute and permanent neurologic complications in children with CHD, including tetralogy of Fallot, ventricular septal defect, tricuspid atresia, anomalous pulmonary veins, and atrial septal defect [28]. None of these children had any known neurologic abnormalities preoperatively.…”

“…Postoperative EEG monitoring detects seizures that clinically would be missed due to pharmacologic neuromuscular blockade and sedation, including subclinical seizure activity [28]. Seizures may occur secondary to cerebral injury and worsen pre-existing or ongoing neuronal damage.…”

“…However, EEG slowing was not associated with neurologic deficits. EEG slowing was actually more common in children who had shorter periods of CPB and lower levels of markers for inflammation and oxidative stress [28]. …”