Should We Prolong the Observation Period for Neurological Recovery After Cardiac Arrest?

Objectives: To evaluate whether the recommended observation period of 7 days for cardiac arrest survivors is sufficient for conscious recovery and to identify the variables associated with eventual neurologic recovery among patients with delayed awakening.

Design: A retrospective cohort study.

Setting: A single tertiary medical center.

Patients: Five-hundred twenty-nine nontraumatic adult cardiac arrest survivors with prearrest favorable neurologic function (Cerebral Performance Category 1-2) who survived to hospital discharge during 2011-2019.

Interventions: The enrolled patients were classified into favorable (Cerebral Performance Category 1-2) and poor (Cerebral Performance Category 3-4) neurologic recovery according to their neurologic function at hospital discharge. Among patients with favorable neurologic recovery, those who recovered within 7 days were assigned to the early recovery group or after 7 days as the late recovery group.

Measurements And Main Results: There were 395 patients exhibiting favorable neurologic recovery (n = 357 in the early group, n = 38 in late group) and 134 patients exhibiting poor neurologic recovery (poor recovery group). Among patients who remained unconscious on day 7, delayed awakening was associated with male sex (odds ratio [OR], 3.905; 95% CI, 1.153-13.221), prehospital return of spontaneous circulation (OR, 7.628; 95% CI, 2.084-27.922), therapeutic hypothermia (OR, 4.320; 95% CI, 1.624-11.488), and extracorporeal cardiopulmonary resuscitation (OR, 4.508; 95% CI, 1.414-14.371). Being transferred from another hospital, however, was less likely to be associated with delayed awakening (OR, 0.061; 95% CI, 0.009-0.431). The median duration for patients to regain clear consciousness in the late recovery group was 12.12 days. No patient who recovered consciousness had an unfavorable electroencephalography pattern, however, in patients with poor recovery, the 7-day electroencephalography showed 45 patients with generalized suppression (33.6%), two with burst suppression (1.5%), 14 with seizure/epileptic discharge (10.5%), and one with status epilepticus (0.7%).

Conclusions: Up to 9.6% of cardiac arrest patients with favorable outcomes recover consciousness after the recommended 7 days of observation, indicating the observation time of 7 days seems justified but longer duration may be needed. The results of the culturally and clinically isolated population may limit the application to other population.