Effect of stimulus type and temperature on EEG reactivity in cardiac arrest.
OBJECTIVE
Electroencephalogram (EEG) background reactivity is a reliable outcome predictor in cardiac arrest patients post therapeutic hypothermia. However, there is no consensus on modality testing and prior studies reveal only fair to moderate agreement rates. The aim of this study was to explore different stimulus modalities and report interrater agreements.


METHODS
We studied a multicenter, prospectively collected cohort of cardiac arrest patients who underwent therapeutic hypothermia between September 2014 and December 2015. We identified patients with reactivity data and evaluated interrater agreements of different stimulus modalities tested in hypothermia and normothermia.


RESULTS
Of the 60 patients studied, agreement rates were moderate to substantial during hypothermia and fair to moderate during normothermia. Bilateral nipple pressure is more sensitive (80%) when compared to other modalities in eliciting a reactive background in hypothermia. Auditory, nasal tickle, nailbed pressure and nipple pressure reactivity were associated with good outcomes in both hypothermia and normothermia.


CONCLUSIONS
EEG reactivity varies depending on the stimulus testing modality as well as the temperature during which stimulation is performed, with nipple pressure emerging as the most sensitive during hypothermia for reactivity and outcome determination.


CONCLUSIONS
This highlights the importance of multiple stimulus testing modalities in EEG reactivity determination to reduce false negatives and optimize prognostication.
Department of Neurology, Brigham and Women's Hospital, USA. Electronic address: tfantaneanu@partners.org.
Tadeu A
TA
Fantaneanu
Department of Neurology, Brigham and Women's Hospital, USA. Electronic address: btolchin@partners.org.
Benjamin
B
Tolchin
Department of Neurology, Hopital du Valais, Sion, Switzerland; Department of Neurology, Brigham and Women's Hospital, USA. Electronic address: Vincent.alvarez@hopitalvs.ch.
Vincent
V
Alvarez
Intensive Care Medicine Department - Hôpital de Sion, Switzerland. Electronic address: Raymond.friolet@hopitalvs.ch.
Raymond
R
Friolet
CICU Brigham and Women's Hospital, USA. Electronic address: kavery@partners.org.
Kathleen
K
Avery
Cardiovascular Division, Brigham and Women's Hospital, USA. Electronic address: bscirica@partners.org.
Benjamin M
BM
Scirica
Department of Cardiology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA. Electronic address: Molly.h.obrien@gmail.com.
Molly
M
O'Brien
Critical Care & Emergency Neurology, Department of Neurology, Brigham and Women's Hospital, USA. Electronic address: ghenderson@bwh.harvard.edu.
Galen V
GV
Henderson
Department of Neurology, Brigham and Women's Hospital, USA. Electronic address: Jlee38@partners.org.
Jong Woo
JW
Lee
D000161:Acoustic Stimulation / Q000379:methods*; D000328:Adult; D000368:Aged; D015331:Cohort Studies; D004569:Electroencephalography / Q000379:methods*; D005260:Female; D006323:Heart Arrest / Q000175:diagnosis / Q000503:physiopathology* / Q000628:therapy; D006801:Humans; D007036:Hypothermia, Induced / Q000379:methods*; D008297:Male; D008875:Middle Aged; D010812:Physical Stimulation / Q000379:methods*; D011446:Prospective Studies; D013696:Temperature
Anoxia; Cardiac arrest; Coma; Continuous EEG monitoring; EEG; EEG reactivity; Therapeutic hypothermia