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ST. PAUL, Minn. -- The lack of specific neurologic signs predict accurately which patients who are comatose following cardiopulmonary resuscitation will have dismal outcomes, according to fresh American Academy of Neurology guidelines.
ST. PAUL, Minn., July 24 -- The lack of specific neurologic signs predict accurately which patients who are comatose following cardiopulmonary resuscitation will have dismal outcomes, according to fresh American Academy of Neurology guidelines.
"Pupillary light response, corneal reflexes, motor responses to pain, myoclonus status epilepticus, serum neuron-specific enolase, and somatosensory evoked potential studies can reliably assist in accurately predicting poor outcome in comatose patients after cardiopulmonary resuscitation for cardiac arrest," wrote Eelco Wijdicks, M.D., of the Mayo Clinic in Rochester, Minn., and colleagues.
The authors of the guidelines, published in the July 25 issue of Neurology, arrived at their conclusions following a review of the medical literature.
Unfortunately, while signs of a negative outcome are abundant, there are no reliable predictors for a favorable outcome, the investigators found.
The information can help clinicians and families make decisions about critical care options, they Dr. Wijdicks.
"In the midst of a catastrophe, families are subsumed with grief from an ordeal that undermines all their coping mechanisms. It's important for family members to talk with a neurologist when faced with this situation," they said.
"Neurologists can provide accurate information about assessment and the likelihood of recovery. If the probability of devastating neurological disability is high, family members may prefer no further resuscitation, no surgical interventions or the withdrawal of critical care," they added. "These decisions should be made after understanding the patient's prior advance directives, or instructions for what type of care the patient would like to receive."
The authors looked at studies published between 1966 and 2006 that explored predictors of death or unconsciousness after one month, or unconsciousness or severe disability after six months in patients who remained in comas following CPR.
They looked at seven variables to determine whether they had prognostic value. The variables were:
To be included in the analysis, the studies had to look at patients ages 17 years or older with confirmed cardiac arrest, with coma defined as a Glasgow Coma Scale score sum score of eight or less, "persistent unresponsiveness," or "not regaining consciousness."
They defined a poor outcome as death or persisting unconsciousness after one month, or death, persisting unconsciousness, or severe disability requiring full nursing care after six months.
"We chose these outcome measures because the chance of survival without severe motor or cognitive disability is virtually nil in patients who are vegetative for one month or more after CPR or in patients who are severely disabled after for six months or more," they wrote.
The authors used evidence-based medicine techniques to identify four class I studies (randomized controlled trials, three class II studies (prospective matched cohort or similar designs), and five class III studies (all other controlled trial designs) on clinical findings and circumstances.
From these studies, they determined that the strongest predictors of poor outcome after CPR are absent papillary light response or corneal reflexes, and extensor or no motor response to pain after 3 days of observation (all level A, the highest level of evidence). Additionally, they found that myoclonus status epilepticus was also a likely predictor of poor prognosis in patients who remain comatose after CPR (level B).
In contrast, they found that prognosis cannot be based on circumstances of CPR or elevated body temperature.
In addition, "anoxia time, duration of CPR, and cause of cardiac arrest are related to poor outcome after CPR, but none of these variables can discriminate accurately between patients with poor and those with favorable outcomes," they wrote.
The authors next considered whether electrophysiology studies could provide accurate clues point to clinical course. They identified one class I, one class II, and nine class III studies on electrophysiology.
They found level B evidence that bilateral absent cortical responses on somatosensory evoked potential studies recorded three days after CPR could predict poor outcomes. Two other measures, burst suppression or generalized epileptiform discharges on electroencephalography (EEG) predicted poor outcomes "but with insufficient prognostic accuracy (level C)."
Among 15 studies of biochemical markers for poor outcomes in these patients, they found that only one - serum neuron-specific enolase higher than 33 mcg/L - predicted poor outcome (level B)
Of 10 class IV studies (uncontrolled cases series, case reports, or expert opinion) on brain monitoring and neuroimaging, there was insufficient evidence to either prove or disprove their prognostic value, the guidelines authors wrote.
Armed with this information, neurologists can help guide the families of critically ill patients through what may be agonizing decisions, the investigators noted.
"When a poor outcome is anticipated, the need for life supportive care (mechanical ventilation, use of vasopressors or inotropic agents to hemodynamically stabilize the patient) must be discussed," they wrote. "Fully informed and more certain, the family or proxy is allowed to rethink resuscitation orders or even to adjust the level of care to comfort measures only. However, these decisions should be made after best interpretation of advance directives or the previously voiced wishes of the patient.