Acute brain failure in severe sepsis: a prospective study in the medical intensive care unit utilizing continuous EEG monitoring.

PURPOSE

Investigate the prevalence, risk factors and impact of continuous EEG (cEEG) abnormalities on mortality through the 1-year follow-up period in patients with severe sepsis.

METHODS

Prospective, single-center, observational study of consecutive patients admitted with severe sepsis to the Medical ICU at an academic medical center.

RESULTS

A total of 98 patients with 100 episodes of severe sepsis were included; 49 patients (50%) were female, median age was 60 (IQR 52-74), the median non-neuro APACHE II score was 23.5 (IQR 18-28) and median non-neuro SOFA score was 8 (IQR 6-11). Twenty-five episodes had periodic discharges (PD), of which 11 had nonconvulsive seizures (NCS). No patient had NCS without PD. Prior neurological history was associated with a higher risk of PD or NCS (45 vs. 17%; CI 1.53-10.43), while the non-neuro APACHE II, non-neuro SOFA, severity of cardiovascular shock and presence of sedation during cEEG were associated with a lower risk of PD or NCS. Clinical seizures before cEEG were associated with a higher risk of nonconvulsive status epilepticus (24 vs. 6%; CI 1.42-19.94) while the non-neuro APACHE II and non-neuro SOFA scores were associated with a lower risk. Lack of EEG reactivity was present in 28% of episodes. In the survival analysis, a lack of EEG reactivity was associated with higher 1-year mortality [mean survival time 3.3 (95% CI 1.8-4.9) vs. 7.5 (6.4-8.7) months; p = 0.002] but the presence of PD or NCS was not [mean survival time 3.3 (95% CI 1.8-4.9) vs. 7.5 (6.4-8.7) months; p = 0.592]. Lack of reactivity was more frequent in patients on continuous sedation during cEEG. In patients with available 1-year data (34% of the episodes), 82% had good functional outcome (mRS ≤ 3, n = 27). There were no significant predictors of functional outcome, late cognition, and no patient with complete follow-up data developed late seizure or new epilepsy.

CONCLUSIONS

NCS and PD are common in patients with severe sepsis and altered mental status. They were less frequent among the most severely sick patients and were not associated with outcome in this study. Lack of EEG reactivity was more frequent in patients on continuous sedation and was associated with mortality up to 1 year after discharge. Larger studies are needed to confirm these findings in a broader population and to further evaluate long-term cognitive outcome, risk of late seizure and epilepsy.