ICU: Increased EEG Brain Wave Monitoring and Survival

MedicalResearch.com Interview with:
John Ney, MD, MPH
Clinical Assistant Professor,
Department of Neurology,
University of Washington
[email protected]

MedicalResearch.com: What are the main findings of the study?

Dr. Ney: My colleagues and I used a large, publicly available dataset to examine the usage and effectiveness of electroencephalography (EEG) in adult intensive care units (ICUs) in the United States over a five year period.  We compared routine EEG, which consists of a portable machine hooked up to the patient to record brainwaves for a short duration, usually 20-40 minutes, with continuous EEG monitoring, where a patient’s brainwaves are recorded continuously for 24 hours or more and examined, ideally in real-time.  Because most patients in the ICU are comatose, we have generally poor and crude indicators of their brain function.  ICU patients are particularly at risk for non-convulsive seizures, where the brain is seizing, but there are few outward signs of a seizure.  EEG is the only means of detecting non-convulsive seizures, and is useful in determining the brain’s reactions to drugs, monitoring for stroke and other abnormal activity.

Our main finding is that ICU patients receiving continuous EEG monitoring was associated with increased survival relative to those who received routine EEG only.    In our sample, 39% of ICU patients who received routine EEG died compared to only 25% of those with continuous EEG monitoring. This finding was both substantial and statistically significant, even after adjustment for age and other demographics, clinical disease comorbidity severity measures, and hospital factors.  Although continuous EEG monitoring was more expensive, the increase in hospital charges were not significant after adjustment.


MedicalResearch.com: Were any of the findings unexpected? 

Dr. Ney: The mortality benefit for continuous EEG monitoring was unexpected, in part because our expectation was that patients with more severe disease would be more likely to receive this emerging technology.   The benefits of continuous EEG monitoring have been touted for many years at major academic medical centers like UCLA, Yale, and Harvard.  However, we found that there although continuous EEG monitoring was more often performed at these centers, that there was no effect to hospital teaching (academic) status on inpatient mortality when continuous EEG monitoring was used.  Likewise, although patients with a primary neurological diagnosis were more likely to receive continuous EEG monitoring than routine EEG, the mortality benefit was present in patients with non-neurological primary diagnoses.  This suggests that the association with survival is related directly to continuous EEG monitoring, and that this finding may be generalizable outside academic centers and specialized neurological intensive care units.

MedicalResearch.com:  What should clinicians and patients take away from your report?

Dr. Ney: In our study, we looked only at the small subset of ICU patients who received electroencephalography.  But among ICU patients where EEG was indicated, due to clinical suspicion, failure to wake up after removal of sedating medications, or overt seizure activity, continuous EEG monitoring has clear benefits over the performance of a routine EEG.  Our study shows that the use of this technology is growing dramatically (increasing 263% during the five year period examined).  The cost of continuous EEG monitoring, in technology infrastructure, equipment, and labor are considerable, but are outweighed by the potential benefits.  If the results from this study are confirmed with future research and clinical trials , we may find that real-time brain monitoring with continuous EEG in the ICU becomes as common as ICU cardiac monitoring and telemetry.

MedicalResearch.com: What recommendations do you have for future research as a result of this study?

Dr. Ney:  Our study focused on adults, and only compared among those receiving EEG of some kind.  We did not compare to the ICU population as a whole, nor did we look at children.  The clinical data available in the dataset that we used was limited to coded procedures, diagnoses, and mortality.  We can postulate the reason why this effect might occur-i.e. more scrutiny of brainwaves leads to faster reactions and better management of evolving neurological insults, but this remains conjecture.  There may be unseen selection bias in this retrospective cross-sectional study.  So there are plenty of opportunities to look at the findings in a wider ICU population, especially in more clinical datasets, and ultimately with prospective, randomized trials to determine the true efficacy of continuous EEG monitoring.

Citation:

Continuous and routine EEG in intensive care
Utilization and outcomes, United States 2005–2009

John P. Ney, MD, MPH, David N. van der Goes, PhD, Marc R. Nuwer, MD, PhD, Lonnie Nelson, PhD and Matthew A. Eccher, MD, MSPH

Published online before print November 1, 2013, doi: 10.1212/01.wnl.0000436948.93399.2a Neurology 10.1212/01.wnl.0000436948.93399.2

 

Last Updated on November 3, 2014 by Marie Benz MD FAAD

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