Surgery and magnetic resonance imaging increase the risk of hypothermia in infants.

AIM: Maintaining normothermia is a tenet of neonatal care. However, neonatal thermal care guidelines applicable to intra-hospital transport beyond the neonatal intensive care unit (NICU) and during surgery or magnetic resonance imaging (MRI) are lacking. The aim of this study is to determine the proportion of infants normothermic (36.5-37.5°C) on return to NICU after management during surgery and MRI, and during standard clinical care in both environments. METHODS: Sixty-two newborns requiring either surgery in the operating theatre (OT) (n = 41) or an MRI scan (n = 21) at the Royal Children's Hospital (Melbourne) NICU were prospectively studied. Core temperature, along with cardiorespiratory parameters, was continuously measured from 15 min prior to leaving the NICU until 60 min after returning. Passive and active warming (intra-operatively) was at clinician discretion. RESULTS: The study reported 90% of infants were normothermic before leaving NICU: 86% (MRI) and 93% (OT). Only 52% of infants were normothermic on return to NICU (relative risk (RR) 1.75; 95% confidence interval (CI) 1.39-2.31; number needed to harm (NNH) 2.6). Between departure from the NICU and commencement of surgery, core temperature decreased by mean 0.81°C (95% CI 0.30-1.33; P = 0.0001, analysis of variance), with only 24% of infants normothermic when surgery began (P < 0.0001; RR 3.80 (95% CI 2.33-6.74); NNH 1.5). After an MRI, infants were a mean 0.41°C (95% CI 0.16-0.67) colder than immediately before entering the scanner (P = 0.001, analysis of variance), with only 43% being normothermic (P = 0.003; RR 2.11 (95% CI 1.35-3.74); NNH 2.1). CONCLUSION: Unintentional hypothermia is a common occurrence during surgery in the OT and MRI in neonates, indicating that evidence-based warming strategies to prevent hypothermia should be developed.

Cognition and behaviour in children with congenital abdominal wall defects.

AIM: To characterise neurodevelopment at age two years and cognition and behaviour at age five years in children born with abdominal wall defects (gastroschisis or exomphalos). STUDY DESIGN: Participants were treated as neonates for gastroschisis or exomphalos and invited for routine clinical follow-up at ages two and five years. Thirty-nine two year-olds and 20 five year-olds with gastroschisis and 20 two year-olds and 10 five year-olds with exomphalos returned for age-appropriate assessments of development (two years) and intellectual functioning (IQ), executive function, and behavioural problems. Results were compared with normative data from the tests and published data from local term-born children. RESULTS: For both gastroschisis and exomphalos two year-olds, neurodevelopment was in line with the test normative data, but below the level of local normative data for all domains (effect sizes from -0.4 to -1.4 standard deviations). At five years, children with gastroschisis performed similarly to the normative mean for IQ but had high rates of various executive functioning problems on parent report (18-41% compared with 7% expected from norms). There was also a tendency for increased frequency of internalising problems (33% compared with normative expectation of 16%). Five year-olds with exomphalos also performed similarly to the normative mean for IQ and had low rates of executive and behavioural problems. CONCLUSIONS: Survivors of gastroschisis and exomphalos may be at risk of poor neurodevelopment in toddlerhood, depending on the reference group, and children with gastroschisis may be particularly at risk for executive functioning difficulties despite an IQ within normal limits.

Perioperative risk factors for impaired neurodevelopment after cardiac surgery in early infancy.

OBJECTIVE: Historical cohort studies have reported adverse neurodevelopment following cardiac surgery during early infancy. Advances in surgical techniques and perioperative care have coincided with updating of neurodevelopmental assessment tools. We aimed to determine perioperative risk factors for impaired neurodevelopment at 2 years following surgery for congenital heart disease (CHD) in early infancy. DESIGN AND PATIENTS: We undertook a prospective longitudinal study of 153 full-term infants undergoing surgery for CHD before 2 months of age. Infants were excluded if they had a genetic syndrome associated with neurodevelopmental impairment. OUTCOME MEASURES: Predefined perioperative parameters were recorded and infants were classified according to cardiac anatomy. At 2 years, survivors were assessed using the Bayley Scales of Infant Development-III. RESULTS: At 2 years, 130 children (98% of survivors) were assessed. Mean cognitive, language and motor scores were 93.4±13.6, 93.6±16.1 and 96.8±12.5 respectively (100±15 norm). Twenty (13%) died and 12 (9%) survivors had severe impairment (score <70), mostly language (8%). The lowest scores were in infants born with single ventricle physiology with obstruction to the pulmonary circulation who required a neonatal systemic-to-pulmonary artery shunt. Additional risk factors for impairment included reduced gestational age, postoperative elevation of lactate or S100B and repeat cardiac surgery. CONCLUSIONS: In the modern era of infant cardiac surgery and perioperative care, children continue to demonstrate neurodevelopmental delays. The use of updated assessment tools has revealed early language dysfunction and relative sparing of motor function. Ongoing follow-up is critical in this high-risk population.

Usefulness of routine head ultrasound scans before surgery for congenital heart disease.

OBJECTIVE: The purpose of this study was to assess the utility of preoperative head ultrasound scan (HUS) in a cohort of newborns also undergoing preoperative MRI as part of a prospective research study of brain injury in infants having surgery for congenital heart disease (CHD). METHODS: A total of 167 infants diagnosed with CHD were included in this 3-center study. None of the patients had clinical signs or symptoms of preoperative brain injury, and all patients received both HUS and brain MRI before undergoing surgical intervention. HUS and MRI results were reported by experienced neuroradiologists who were blinded to any specific clinical details of the study participants. The findings of the individual imaging modes were compared to evaluate for the presence of brain injury. RESULTS: Preoperative brain injury was present on HUS in 5 infants (3%) and on MRI in 44 infants (26%) (P < .001). Four of the HUS showed intraventricular hemorrhage not seen on MRI, suggesting false-positive results, and the fifth showed periventricular leukomalacia. The predominant MRI abnormality was white matter injury (n = 32). Other findings included infarct (n = 16) and hemorrhage (n = 5). CONCLUSIONS: Preoperative brain injury on MRI was present in 26% of infants with CHD, but only 3% had any evidence of brain injury on HUS. Among positive HUS, 80% were false-positive results. Our findings suggest that routine HUS is not indicated in asymptomatic term or near-term neonates undergoing surgery for CHD, and MRI may be a preferable tool when the assessment of these infants is warranted.

New white matter brain injury after infant heart surgery is associated with diagnostic group and the use of circulatory arrest.

BACKGROUND: Abnormalities on magnetic resonance imaging scans are common both before and after surgery for congenital heart disease in early infancy. The aim of this study was to prospectively investigate the nature, timing, and consequences of brain injury on magnetic resonance imaging in a cohort of young infants undergoing surgery for congenital heart disease both with and without cardiopulmonary bypass. METHODS AND RESULTS: A total of 153 infants undergoing surgery for congenital heart disease at <8 weeks of age underwent serial magnetic resonance imaging scans before and after surgery and at 3 months of age, as well as neurodevelopmental assessment at 2 years of age. White matter injury (WMI) was the commonest type of injury both before and after surgery. It occurred in 20% of infants before surgery and was associated with a less mature brain. New WMI after surgery was present in 44% of infants and at similar rates after surgery with or without cardiopulmonary bypass. The most important association was diagnostic group (P<0.001). In infants having arch reconstruction, the use and duration of circulatory arrest were significantly associated with new WMI. New WMI was also associated with the duration of cardiopulmonary bypass, postoperative lactate level, brain maturity, and WMI before surgery. Brain immaturity but not brain injury was associated with impaired neurodevelopment at 2 years of age. CONCLUSIONS: New WMI is common after surgery for congenital heart disease and occurs at the same rate in infants undergoing surgery with and without cardiopulmonary bypass. New WMI is associated with diagnostic group and, in infants undergoing arch surgery, the use of circulatory arrest.

Perioperative amplitude-integrated EEG and neurodevelopment in infants with congenital heart disease.

PURPOSE: Perioperative brain injury is common in young infants undergoing cardiac surgery. We aimed to determine the relationship between perioperative electrical seizures, the background pattern of amplitude-integrated electroencephalography (aEEG) and 2-year neurodevelopmental outcome in young infants undergoing surgery for congenital heart disease. METHODS: A total of 150 newborn infants undergoing cardiac surgery underwent aEEG monitoring prior to and during surgery, and for 72 h postoperatively. Two blinded assessors reviewed the aEEGs for seizure activity and background pattern. Survivors underwent neurodevelopmental outcome assessment using the Bayley Scales of Infant Development (3rd edn.) at 2 years. RESULTS: The median age at surgery was 7 days (IQR 4-11). Cardiopulmonary bypass was used in 83 %. Perioperative electrical seizures occurred in 30 %, of whom 1/4 had a clinical correlate, but were not associated with 2-year outcome. Recovery to a continuous background occurred at a median 6 (3-13) h and sleep-wake cycling recovered at 21 (14-30) h. Prolonged aEEG recovery was associated with increased mortality and worse neurodevelopmental outcome. Failure of the aEEG to recover to a continuous background by 48 postoperative hours was associated with impairment in all outcome domains (p < 0.05). Continued abnormal aEEG at 7 postoperative days was highly associated with mortality (p < 0.001). CONCLUSIONS: Perioperative seizures were common in this cohort of infants but did not impact on 2-year neurodevelopmental outcome. Delayed recovery in aEEG background was associated with increased risk of early mortality and worse neurodevelopment. Ongoing monitoring of the survivors is essential to determine the longer-term significance of these findings.

Amplitude-integrated electroencephalography and brain injury in infants undergoing Norwood-type operations.

BACKGROUND: Perioperative brain injury is common in infants undergoing cardiac surgery. Amplitude-integrated electroencephalography (aEEG) provides real-time neurologic monitoring and can identify seizures and abnormalities of background cerebral activity. We aimed to determine the incidence of perioperative electrical seizures, and to establish the background pattern of aEEG, in neonates undergoing Norwood-type palliations for complex congenital heart disease in relation to outcome at 2 years. METHODS: Thirty-nine full-term neonates undergoing Norwood-type operations underwent aEEG monitoring before and during surgery and for 72 hours postoperatively. The perfusion strategy included full-flow moderately hypothermic cardiopulmonary bypass with antegrade cerebral perfusion. Amplitude-integrated electroencephalography tracings were reviewed for seizure activity and background pattern. Survivors underwent neurodevelopmental outcome assessment using the Bayley Scales of Infant Development (3rd edition) at 2 years of age. RESULTS: Thirteen (33%) infants had electrical seizures, including 9 with intraoperative seizures and 7 with postoperative seizures. Seizures were associated with significantly increased mortality, but not with neurodevelopmental impairment in survivors. Delay in recovery of the aEEG background beyond 48 hours was also associated with increased mortality and worse motor development. CONCLUSIONS: Perioperative seizures were common in this cohort. Intraoperative seizures predominantly affected the left hemisphere during antegrade cerebral perfusion. Delayed recovery in aEEG background was associated with increased risk of early mortality and worse motor development. Ongoing monitoring is essential to determine the longer-term significance of these findings.

A systematic review of motor and cognitive outcomes after early surgery for congenital heart disease.

CONTEXT: Brain injury is the most common long-term complication of congenital heart disease requiring surgery during infancy. It is clear that the youngest patients undergoing cardiac surgery, primarily neonates and young infants, are at the greatest risk for brain injury. Developmental anomalies sustained early in life have lifelong repercussions. OBJECTIVE: We conducted a systematic review to examine longitudinal studies of cognitive and/or motor outcome after cardiac surgery during early infancy. METHODS: Electronic searches were performed in Medline, the Cumulative Index to Nursing and Allied Health Literature (Cinahl), and Embase (1998-2008). The search strategy yielded 327 articles, of which 65 were reviewed. Eight cohorts provided prospective data regarding the cognitive and/or motor outcome of infants who had undergone surgery for congenital heart disease before 6 months of age. Two authors, Ms Snookes and Dr Gunn, independently extracted data and presented results according to 3 subgroups for age of follow-up: early development (1 to <3 years); preschool age (3-5 years); and school age (>5 to 17 years). Weighted analysis was undertaken to pool the results of studies when appropriate. RESULTS: All of the identified studies reported results of the Bayley Scales of Infant Development for children younger than the age of 3. Outcome data as reported by the Bayley Scales were combined for infants assessed at 1 year of age, revealing a weighted mean Mental Development Index of 90.3 (95% confidence interval: 88.9-91.6) and Psychomotor Development Index of 78.1 (95% confidence interval: 76.4-79.7). Additional analysis was limited by a lack of data at preschool and school age. CONCLUSIONS: With this review we identified a limited number of prospective studies that systematically addressed outcome in patients at the highest risk. These studies consistently revealed cognitive and motor delay in children after cardiac surgery during early infancy. Additional investigation is required to ascertain the consequences of such impairment during later childhood and into adult life.