Recommendations for Improving Study Outcomes

Future outcome assessments in cardiac arrest survivors should include neurocognitive testing, patient-reported quality-of-life measures, and psychological assessment; in particular, these should be included in studies measuring delayed outcomes (testing times recommended at 90 days or later). Furthermore, there is a need for validated tools, such as those used in stroke or traumatic brain injury studies, which embrace common data elements and standardized outcome testing.

Recommendations for Timing of Neurologic Prognostication

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Neurologic prognostication of a patient after cardiac arrest requires frequent evaluation and reevaluation. The timing of the index test should adequately predict neurologic prognosis and should ensure adequate time is given for the patient awakening and recovering before decisions to limit care or WLST.

Recommendations for Factors of Neurologic Prognostication

Patient characteristics and clinical factors before cardiac arrest are limited in their ability to establish neurologic prognostication, but variables including age, comorbidities, and lifestyle may impact the study design and interpretation of results. Similarly, the association of intra-arrest factors, such as duration of cardiac arrest, presentation of rhythm, and duration and quality of CPR, with overall survival still remain uncertain.

Recommendations for Post-arrest Evaluation

Assessing the extent of neurologic injury is crucial in neurologic prognostication and requires significant accuracy in all testing, including bedside examination, neurophysiological testing, neuroimaging, and biomarker testing. The AHA recommends testing be performed by well-trained and experienced examiners, and their role and qualification should be described in the study.

Assessment of consciousness can be subject to bias. To avoid this, examiners should use validated scales to quantify cognitive abilities. Brain stem integrity can be evidenced by heart rate variability as well as in the presence or absence of reflexes (such as cough, gag, pupillary, and corneal reflexes). Due to their association with poor prognosis, seizures reported as part of neurologic prognostication studies require the use of electroencephalography to confirm their activity and response to treatment.

Recommendations for Biochemical Markers

Biochemical markers can provide evidence of injury and can be obtained from cerebrospinal fluid (CSF) samples or routine blood sampling. In reporting of blood and CSF biomarkers, investigators must include clear definitions of normal ranges by age. Serial testing, rather than relying on any individual values, is highly recommended as it reflects progression of injury over time.

Recommendations for Neuroimaging

Most neuroimaging modalities, even the most sensitive, are best performed several days after cardiac arrest as there is typically a delay in the imaging appearance of hypoxic-ischemic changes in the brain. Neuroimaging in neurologic prognostication studies should be reported as an objective quantification (volume of injury) or qualitative assessment (based on injury site and related to functional outcomes). Although it is not yet validated for use in neurologic prognostication, it is recommended that neuroimaging tests be performed multiple times to capture and quantify the evolution of brain injury.

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Recommendations for Post-arrest Variables

The impact of medications and therapies used in resuscitation and periresuscitation management should be accounted for in neurologic prognostication studies. The extent of organ failure in patients should also be considered in the context of neurologic outcomes, as organ dysfunction is extremely common in survivors of cardiac arrest. The use of extracorporeal membrane oxygenation, which may improve survival in a subpopulation of patients, should establish clearly defined patient selection criteria.

As a special consideration, the AHA recommends that informed consent from a legally authorized representative must be included in the design of neurologic prognostication studies, especially in clinical trials. Families should be adequately prepared to help make care decisions, including WLST, with the clear communication and guidance of healthcare professionals.

Final Remarks

In a statement from Romergryko G. Geocadin, MD, Professor of Neurology at Johns Hopkins Hospital and study author notes, “[a]t the current state of affairs, we have to acknowledge the limitations in our practices in this area because we don’t have high-quality science to back our decision-making.” He goes on to remark that, “[w]e owe it to patients and families to ensure we are doing the best to both not prolong unnecessary suffering while balancing that with not withdrawing care too soon if the person has the potential to recover with a reasonably good quality of life.”2


1. Geocadin RG, Callaway CW, Fink EL, et al. Standards for studies of neurologic prognostication in comatose survivors of cardiac arrest: a scientific statement from the American Heart Association [published online July 11, 2019]. Circulation. doi:10.1161/CIR.0000000000000702

2. Better science needed to support clinical predictors that link cardiac arrest, brain injury, and death: a statement from the American Heart Association [news release]. Dallas, TX: American Heart Association; July 11, 2019.

This article originally appeared on Neurology Advisor