Clinical paperPost resuscitation prognostication by EEG in 24 vs 48 h of targeted temperature management
Introduction
Out-of-hospital cardiac arrest (OHCA) affects an estimated 400,000 people in Europe each year.1 Survival rates are approximately 10% in overall survival and 50%2 in patients admitted to the intensive care unit (ICU). Post-resuscitation care in the ICU includes target temperature management (TTM) to 32–36 °C for at least 24 h, but optimal depth3 and duration3 is still subject to research and discussion.
The most common cause of death in the ICU after OHCA, is hypoxic-ischemic encephalopathy, accounting for 60–70% of deaths.6, 7, 8 Further, 2–4% of survivors have serious neurologic deficits.3, 4
Timely and correct prognostication is of vital importance, both to avoid self-fulfilling prophecies and to guide physicians in decisions on withdrawal of care. EEG is an important prognostic tool and also recommended for ruling out subclinical seizures.5 However, inter-rater variability6 and the confounding effects of sedation and TTM together with the variety of classification systems makes it difficult to define optimal use of EEG for prognostic purposes.7 It is important to study the effects of TTM on EEG patterns in order to understand how to refine prognostication and evaluate possible treatment effects of different TTM regimens. The aim of the present study was to investigate the impact of prolonged TTM on prognostic performance and EEG evolution over time, using two recently proposed EEG pattern classification models; the Hofmeijer model8 and the Westhall9 model, following the standardized EEG terminology proposed by the American Clinical Neurophysiology Society (ACNS).10
Section snippets
Patients
The present study is a sub-study of the “Targeted Temperature Management for 48 vs. 24 h and Neurologic Outcome After Out-of-Hospital Cardiac Arrest: A Randomized Clinical Trial” (the TTH48 trial)3 involving the 159 patients enrolled in the ICUs at Aarhus University Hospital, Denmark, and Stavanger University Hospital, Norway. The inclusion criteria of the TTH48 trial were the following: OHCA with a presumed cardiac origin, Glasgow Coma Scale below 8, sustained spontaneous circulation after
Results
We recorded 120 EEGs at 24 h (Fig. 1), median hours from TT to EEG; 20 h (IQR: 16–23, range: 8–36) and median hours from cardiac arrest to EEG; 25 h (IQR: 21–28, range: 14–40). In 44 of these patients, we also recorded EEGs at 48 h, median hours from TT to EEG; 43 h (IQR: 38–46, range: 25–65) and median hours from cardiac arrest to EEG; 49 h (IQR: 43–53, range: 31–68). We found no differences between TTM groups in time from cardiac arrest to TT or cardiac arrest to EEG (all p-values above
Discussion
We found no significant differences between TTM groups in specificity and sensitivity as assessed on a dichotomized CPC-scale after six months, however, numbers were small in each group at 48 h and our results should be validated in larger trials. We found no significant differences between prognostication at 24 h compared to 48 h measured in specificity and sensitivity of EEG categories, but using EEG reactivity, prognostication was best at 24 h compared to 48 h. Both classification models
Conclusion
Our results suggest no differences in prognostication between TTM groups using two models proposed by Westhall and Hofmeijer. We found no significant differences at 24 h compared to 48 h measured in specificity and sensitivity of EEG categories, but using EEG reactivity, prognostication was significantly better at 24 h compared to 48 h. Both classification models performed very well in good outcome prediction. Models for prediction of poor outcome within 48 h should not include non-identical
Conflicts of interest
Christophe H. V. Duez received funding from the following private foundations: The Viggo and Helene Bruun foundation, the Lily Benthine Lunds foundation of 1st of june 1978, the Director Jacob Madsen & wife Olga Madsen foundation and the Grocer A. V. Lykfeldt and wife foundation. Foundations had no influence on study design, data collection, analysis or data interpretation.
Acknowledgements
We wish to thank the staffs at the intensive care units of Stavanger University Hospital and Aarhus University hospital.
References (23)
- et al.
EuReCa ONE – ONE month – ONE Europe – ONE goal
Resuscitation
(2014) - et al.
The influence of induced hypothermia and delayed prognostication on the mode of death after cardiac arrest
Resuscitation
(2013) - et al.
Large inter-rater variability on EEG-reactivity is improved by a novel quantitative method
Clin Neurophysiol
(2018) - et al.
Cardiac arrest and cardiopulmonary resuscitation outcome reports: update of the utstein resuscitation registry templates for out-of-Hospital cardiac arrest: a statement for healthcare professionals from a task force of the international liaison committee on resuscitation (American heart association, european resuscitation council, australian and New Zealand council on resuscitation, heart and stroke foundation of Canada, InterAmerican heart foundation, resuscitation council of southern africa, resuscitation council of asia); and the american heart association emergency cardiovascular care committee and the council on cardiopulmonary, critical care, perioperative and resuscitation
Resuscitation
(2015) - et al.
Highly malignant routine EEG predicts poor prognosis after cardiac arrest in the Target Temperature Management trial
Resuscitation
(2018) - et al.
Standardized EEG interpretation in patients after cardiac arrest: correlation with other prognostic predictors
Resuscitation
(2018) - et al.
Prognostication in comatose survivors of cardiac arrest: an advisory statement from the European Resuscitation Council and the European Society of Intensive Care Medicine
Resuscitation
(2014) - et al.
Burst-suppression with identical bursts: a distinct EEG pattern with poor outcome in postanoxic coma
Clin Neurophysiol
(2014) - et al.
Targeted temperature management for 48 vs 24 hours and neurologic outcome after out-of-Hospital cardiac arrest: a randomized clinical trial
JAMA
(2017) - et al.
Targeted temperature management at 33 degrees C versus 36 degrees C after cardiac arrest
N Engl J Med
(2013)