Continuous noninvasive monitoring of barbiturate coma in critically ill children using the Bispectral index monitor.
BACKGROUND
Traumatic brain injury and generalized convulsive status epilepticus (GCSE) are conditions that require aggressive management. Barbiturates are used to lower intracranial pressure or to stop epileptiform activity, with the aim being to improve neurological outcome. Dosing of barbiturates is usually guided by the extent of induced burst-suppression pattern on the electroencephalogram (EEG). Dosing beyond the point of burst suppression may increase the risk for complications without offering further therapeutic benefit. For this reason, careful monitoring of EEG parameters is mandatory. A prospective study was conducted to evaluate the usefulness of the bispectral index suppression ratio for monitoring barbiturate coma.


METHODS
A prospective observational pilot study was performed at a paediatric (surgical) intensive care unit, including all children with barbiturate-induced coma after traumatic brain injury or GCSE. The BIS (Bispectral index) monitor expresses a suppression ratio, which represents the percentage of epochs per minute in which the EEG was suppressed. Suppression ratios from the BIS monitor were compared with suppression ratios of full-channel EEG as assessed by quantitative visual analysis.


RESULTS
Five patients with GCSE and three patients after traumatic brain injury (median age 11.6 years, range 4 months to 15 years) were included. In four patients the correlation between the suppression ratios of the BIS and EEG could be determined; the average correlation was 0.68. In two patients, suppression ratios were either high or low, with no intermediate values. This precluded determination of correlation values, as did the isoelectric EEG in a further two patients. In the latter patients, the mean +/- standard error BIS suppression ratio was 95 +/- 1.6.


CONCLUSIONS
Correlations between suppression ratios of the BIS and EEG were found to be only moderate. In particular, asymmetrical EEGs and EEGs with short bursts (less than 1 second) may result in aberrant BIS suppression ratios. The BIS monitor potentially aids monitoring of barbiturate-induced coma because it provides continuous data on EEG suppression between full EEG registrations, but it should be used with caution.
Prins
Sandra A
SA
Department of Pediatric Surgery, Intensive Care Unit, Erasmus MC, University Medical Center, Sophia Children's Hospital, Dr, Molewaterplein 60, 3015 GJ, Rotterdam, The Netherlands.
de Hoog
Matthijs
M
Blok
Joleen H
JH
Tibboel
Dick
D
Visser
Gerhard H
GH
D000293:Adolescent; D001463:Barbiturates / Q000097:blood / Q000627:therapeutic use*; D001930:Brain Injuries / Q000188:drug therapy*; D002648:Child; D002675:Child, Preschool; D003128:Coma / Q000097:blood / Q000139:chemically induced*; D016638:Critical Illness; D016903:Drug Monitoring / Q000295:instrumentation* / Q000379:methods*; D004569:Electroencephalography / Q000295:instrumentation / Q000379:methods; D006801:Humans; D007223:Infant; D010865:Pilot Projects; D011446:Prospective Studies; D013226:Status Epilepticus / Q000188:drug therapy*
D001463:Barbiturates