by Nathalie Jetté, MD, MSc, FRCPC and Churl-Su Kwon, MD, MPH
The use of continuous EEG (cEEG) in the Intensive Care Unitis increasing. As indicated by the American Clinical Neurophysiology Society, current indications for this non-invasive tool include: monitoring/diagnosis of seizures and/or status epilepticus, detecting cerebral ischemia, measuring sedation, providing post-arrest prognostication1. However, research has been rather sparse in the past decade regarding specific use of cEEG and clinical outcomes in the critically ill.
With the variability in cEEG practices seen across health
systems (timing, length, when to start ensuing treatment) and the fact that it
is resource intense, there is much need to define its optimal use. This will
diminish inconsistencies in cEEG application as well as curtail avoidable
costs, especially with health in the USA experiencing much policy
transformation with linkage of traditional health-care services to value-based
care and highlighting population health and novel mechanisms of health-care
The authors used 2004-2013 data from the National Inpatient Sample
which is the largest cross-sectional, all-payer inpatient healthcare nationwide
database, consisting of information on patient and hospital level factors for
more than seven million hospital discharges annually2. In this study,
mechanically-ventilated adults in intensive care units were sampled and
patients who underwent cEEG were compared to those who did not. cEEG use was
associated with lower in-hospital deaths, as were larger bed size and urban
teaching hospitals. Subgroup analysis showed similar results in patients who
had subarachnoid/intracerebral hemorrhage and altered consciousness unless they
had seizures/status epilepticus likely due to a disease severity confounding
effect. Proportions of critically ill patients who underwent cEEG varied across
hospitals, suggesting discrepancies in hospital resources and expertise. Longer
hospital stays and total hospitalization costs were associated with cEEG utilization,
but justifiable in the setting of decreased mortality of nearly 20%.
This study has many strengths, including the large population
and adjustment for important confounders such as comorbidity. Though it is
carefully designed and the authors are to be congratulated for this important
work, this study is not without limitations, most of which are highlighted by
the authors. These include issues related to the validity of diagnostic coding
which is lacking for NIS-specific data, low sensitivity of ICD coding for
mechanical ventilation, under-ascertainment of cEEG use and lack of
This study highlights that cEEG use for critically ill patients is associated with lower in-hospital deaths and suggests possible under-utilization of cEEG (0.3% of critically ill, though utilization increased more than tenfold from 0.06% in 2004 to 0.8% in 2013). Although these data may warrant continued expansion of cEEG use, explicit cost-analysis quantifying the value of cEEG in the critically ill is essential in future studies to elicit cost-effective strategies. Since survival is seen to differ across diagnoses, rigorous investigation is necessary to develop cEEG evidence-based practices to improve outcomes, decrease variability in care and enhanced cost-benefit frameworks across different populations.
- Herman ST, Abend NS, Bleck TP, et al. Consensus Statement onContinuous EEG in Critically Ill Adults and Children, Part I. J ClinNeurophysiol. 2015;32:87–95.
- Hill CE, Blank LJ, Thibault D, et al. Continuous EEG is associated with favorable hospitalization outcomes for critically ill patients. Neurology Epub 2018 November 30.