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Bispectral index monitoring in children undergoing mild hypothermic cardiopulmonary bypass
P C Laussen1, J A Murphy, D Zurakowski
1Department of Anesthesia, Children's Hospital, Boston, MA 02115, USA. plaussen@cardio.tch.harvard.edu
Insights
The Bispectral index (BIS) may indicate rising consciousness during cardiac anesthesia rewarming in children. This study monitored BIS and stress markers, finding BIS increased during rewarming without correlation to stress responses, suggesting potential awareness risk.
Area of Science:
- Anesthesiology
- Pediatric Cardiac Surgery
- Neurophysiology
Background:
- Atrial septal defect repair in children necessitates careful monitoring of consciousness during anesthesia.
- The Bispectral index (BIS) is a potential tool for assessing the level of consciousness.
Purpose of the Study:
- To evaluate changes in the Bispectral index (BIS) as a monitor of consciousness during pediatric cardiac anesthesia.
- To assess the correlation between BIS and physiological stress responses during cardiac surgery.
Main Methods:
- Prospective cohort study of 15 children undergoing atrial septal defect repair.
- Continuous BIS monitoring alongside hemodynamic and temperature measurements.
- Analysis of serum lactate, glucose, norepinephrine, and epinephrine levels as stress markers.
- Explicit memory testing prior to hospital discharge.
Main Results:
- BIS significantly increased during the rewarming phase of cardiac surgery (P<0.001).
- Elevated lactate, epinephrine, and glucose levels were observed during rewarming.
- No significant correlations were found between BIS and stress markers or hemodynamic changes.
- All patients experienced uneventful recovery with no explicit recall.
Conclusions:
- The rise in BIS during rewarming may indicate an increased level of consciousness in pediatric cardiac surgery patients.
- This finding aligns with the known risk of intraoperative awareness during the rewarming phase.
- BIS monitoring could be valuable for detecting potential awareness during this critical period.
Background:
In this prospective, cohort study of 15 children (median age 7.7 years, range 4.9-16.5 years) undergoing atrial septal defect repair, we evaluated changes in the Bispectral index (BIS) as a potential monitor of level of consciousness during cardiac anaesthesia.
Methods:
Identical cardiac surgery, cardiopulmonary bypass (CPB) and anaesthetic techniques were used, including mild hypothermia and an early extubation protocol. BIS, mean arterial pressure, heart rate and tympanic temperature were recorded at baseline postinduction (Tbaseline), skin incision (Tincis), sternotomy (Tsternot), aortic cannulation (Tcann), nadir temperature (Tnadir), rewarmed (Trewarmed), immediate post-CPB (TpostCPB), chest drain insertion (Tdrains), sternal wires (Twire), skin closure (Tclosed) and spontaneous movement (Tmove). As a measure of stress response, serum lactate, glucose, norepinephrine and epinephrine levels were measured at Tbaseline, Tsternot, Tcann, Tnadir, Trewarmed and Tdrains. Explicit memory testing was undertaken prior to hospital discharge.
Results:
BIS increased significantly during the rewarming phase (Trewarmed versus Tbaseline and Tnadir, P<0.001). Lactate, epinephrine and glucose levels were also significantly elevated at Trewarmed. There were no correlations between BIS and the increase in epinephrine, lactate and glucose during rewarming, nor with changes in heart rate or mean arterial pressure during surgery. All patients had an uneventful recovery without evidence for explicit recall.
Conclusions:
The increase in BIS during the rewarming phase could reflect an increase in conscious level, and is consistent with the reported risk for awareness during this phase of cardiac surgery.
