Comatose Post-cardiac Arrest Patients Research Articles

Hypothermia after cardiac arrest: Expanding the therapeutic scope

Therapeutic hypothermia for 12 to 24 hrs following resuscitation from out-of-hospital cardiac arrest is now recommended by the American Heart Association for the treatment of neurological injury when the initial cardiac rhythm is ventricular fibrillation. However, the role of therapeutic hypothermia is uncertain when the initial cardiac rhythm is asystole or pulseless electrical activity, or when the cardiac arrest is primarily due to a noncardiac cause, such as asphyxia or drug overdose. Given that survival rate in these latter conditions is very low, it is unlikely that clinical trials will be undertaken to test the efficacy of therapeutic hypothermia in this setting because of the very large sample size that would be required to detect a significant difference in outcomes. Therefore, in patients with anoxic brain injury after nonventricular fibrillation cardiac arrest, clinicians will need to balance the possible benefit of therapeutic hypothermia with the possible side effects of this therapy. Given that the side effects of therapeutic hypothermia are generally easily managed in the critical care setting, and there is benefit for anoxic brain injury demonstrated in laboratory studies, consideration may be given to treat comatose post-cardiac arrest patients with therapeutic hypothermia in this setting. Because the induction of therapeutic hypothermia has become more feasible with the development of simple intravenous cooling techniques and specialized equipment for improved temperature control in the critical care unit, it is expected that therapeutic hypothermia will become more widely used in the management of anoxic neurological injury whatever the presenting cardiac rhythm.

Prognostic value of brain diffusion‐weighted imaging after cardiac arrest

Outcome prediction is challenging in comatose postcardiac arrest survivors. We assessed the feasibility and prognostic utility of brain diffusion-weighted magnetic resonance imaging (DWI) during the first week. Consecutive comatose postcardiac arrest patients were prospectively enrolled. AWI data of patients who met predefined specific prognostic criteria were used to determine distinguishing apparent diffusion coefficient (ADC) thresholds. Group 1 criteria were death at 6 months and absent motor response or absent pupillary reflexes or bilateral absent cortical responses at 72 hours or vegetative at 1 month. Group 2 criterion was survival at 6 months with a Glasgow Outcome Scale score of 4 or 5 (group 2A) or 3 (group 2B). The percentage of voxels below different ADC thresholds was calculated at 50 x 10(-6) mm(2)/sec intervals. Overall, 86% of patients underwent DWI. Fifty-one patients with 62 brain DWIs were included. Forty patients met the specific prognostic criteria. The percentage of brain volume with an ADC value less than 650 to 700 x 10(-6)mm(2)/sec best differentiated between Group 1 and Groups 2A and 2B combined (p < 0.001), whereas the 400 to 450 x 10(-6)mm(2)/sec threshold best differentiated between Groups 2A and 2B (p = 0.003). The ideal time window for prognostication using DWI was between 49 and 108 hours after the arrest. When comparing DWI in this time window with the 72-hour neurological examination, DWI improved the sensitivity for predicting poor outcome by 38% while maintaining 100% specificity (p = 0.021). Quantitative DWI in comatose postcardiac arrest survivors holds promise as a prognostic adjunct.

Serum Neuron Specific Enolase to Predict Neurological Outcome After Cardiopulmonary Resuscitation

Despite a large body of resuscitation research, the optimal timing and approach to prognosticating futility after nontraumatic cardiac arrest remains controversial. Postresuscitation anoxic-ischemic encephalopathy may leave patients cognitively disabled and dependent, minimally conscious, or in a persistent vegetative state. Neurologists are frequently called upon to assess comatose postcardiac arrest patients to communicate accurate prognostic information and to assist in planning the most appropriate level of care. Serum neuron specific enolase (NSE), when used in conjunction with other available prognostic tools, may be a useful tool for predicting clinical outcome in this patient population. Determine the clinical utility of a serum NSE measurement for predicting the neurologic outcome of a survivor after resuscitation from a nontraumatic cardiac arrest. We addressed the question through the development of a structured, critically appraised topic. Participants included consultant and resident neurologists, clinical epidemiologists, medical librarian, and clinical content experts in the fields of emergency medicine, cardiac resuscitation, and critical care neurology. Participants started with a clinical scenario and a structured question, devised search strategies, located and compiled the best evidence, performed a critical appraisal, synthesized the results, summarized the evidence, provided commentary, and declared bottom-line conclusions. A single recent prospective cohort study, which assessed the predictive value of serum NSE was selected and appraised. A level of 80 ng/mL was determined to predict persistent coma with a sensitivity of 63% (95% CI, 49%-75%), and a specificity of 100% (95% CI, 97%-100%), positive predictive value (PPV) of 100%, negative predictive value (NPV) of 84%, and a negative LR of 0.37. The specificity of serum NSE levels >80 ng/mL is sufficiently high that, when it is used with other clinical and electrophysiological data, it could be useful as a prognostic indicator of neurologic outcome after cardiac arrest. Although serum NSE is an appealing, simple, readily available test, prediction of neurologic outcome after resuscitation from cardiac arrest must not rely solely on a serum biomarker, but must be determined in the context of other patient characteristics and neurologic examination findings.