After successful resuscitation from certain types of cardiac arrest, total body cooling is now a well established treatment that improves the chances of the brain recovering. This however, has only been definitively proven after a certain type of cardiac arrest that is "ventricular fibrillation / ventricular tachycardia". The purpose of this study is to explore if total body cooling is beneficial for patients recovering from another type of cardiac arrest that is "pulseless electrical activity". HYPOTHESIS: Patients undergoing post-cardiac arrest therapeutic hypothermia have better neurological outcomes if their initial arrest rhythm is pulseless electrical activity (PEA) in comparison to asystole.
STUDY RATIONALE AND BACKGROUND INFORMATION: After successful resuscitation from cardiac arrest the body experiences a period of global reperfusion. During this period, patients may show signs of myocardial stunning, lactic acidosis, neurological injury and reperfusion syndrome. This constellation of findings constitutes what is known as post-cardiac arrest syndrome. The brain appears to be one of the most vulnerable organs to injury during this reperfusion phase and varying degrees of cognitive impairment may be the end result. Inducing mild therapeutic hypothermia has been shown to be protective for the brain in this setting and has been demonstrated to improve neurological recovery. The evidence for this however, is only conclusive in cases where the arrest is in a shockable rhythm i.e. pulseless ventricular tachycardia and ventricular fibrillation. In 2002, two randomized controlled trials were published showing an improvement in neurological outcomes in patients treated with mild therapeutic hypothermia post resuscitation from shockable cardiac arrest. Therapeutic hypothermia has since been widely adopted by most authorities as part of the comprehensive treatment bundle for post cardiac arrest syndrome. Whether there is any benefit for patients arrested in non-shockable rhythms however, is a matter of controversy. Some have reported improved mortality and better neurological outcomes with therapeutic hypothermia in this patient population. Others have reported no benefit or even a trend towards harm. And although the matter remains controversial, the recommendation still stands for therapeutic hypothermia to be offered for all comatose survivors of cardiac arrest whatever the arrest rhythm. Most previous reports have examined the differences between shockable and non-shockable rhythms in terms of neurological outcome and mortality rates after therapeutic hypothermia. To our knowledge, no study has examined the differences in outcome between the two types of non-shockable rhythms, that is pulseless electrical activity (PEA) and asystole. We hypothesize that during PEA arrests, patients may retain some degree of cerebral perfusion and hence have better neurological outcomes post-resuscitation. That is in contrast to asystole where patients are likely to have no cerebral perfusion. In this study we attempt to detect any possible differences in neurological recovery (as indicated by the Cerebral Performance Category scale on hospital discharge) after therapeutic hypothermia, between patients arrested in PEA arrest and those arrested in asystole.
Study Type
OBSERVATIONAL
Enrollment
400
No therapeutic hypothermia was induced.
Hypothermia was induced after successful resuscitation from cardiac arrest.
University Hospital, London Health Sciences Centre, University of Western Ontario
London, Ontario, Canada
Victoria Hospital, London Health Sciences Centre, University of Western Ontario
London, Ontario, Canada
Cerebral performance category score on hospital discharge
Neurological outcome on discharge from hospital as defined by the cerebral performance category (CPC) scale. The CPC scale is a 5 point scale. The outcome measure will be dichotomized into good or bad. Good outcome will be equivalent to CPC scores of 1 \& 2 (where the patient is independent), and bad outcome will be equivalent to CPC scores of 3, 4 \& 5 (where the patient is either dependent or dead). CPC Scale: 1. Functioning normally and independent, possibly with a minor disability. 2. Moderately disabled, still independent. 3. Conscious but with a severe disability, dependent. 4. Unconscious (comatose or in a persistent vegetative state). 5. Brain dead or dead by traditional criteria.
Time frame: Upon discharge from hospital, assessed up to 36 months postcardiac arrest
Hospital length of stay postcardiac arrest
Hospital length of stay (LOS) post-cardiac arrest will be calculated from the day of the cardiac arrest to the day of hospital discharge. If prior to the arrest the patient was an inpatient, we will only count the days from the arrest to discharge. Days spent in hospital prior to the arrest will not be included.
Time frame: Days spent in hospital after successful resuscitation from cardiac arrest, assessed up to 36 months from the date of cardiac arrest
Intensive care unit length of stay postcardiac arrest
The length of stay (LOS) in the intensive care unit (ICU) in days, after successful resuscitation from cardiac arrest.
Time frame: Days spent in the intensive care unit after successful resuscitation from cardiac arrest, assessed up to 36 months from the date of cardiac arrest
Neurological status after hospital discharge
Neurological status as documented on the patient's first outpatient clinic visit, assessed up to 12 months from hospital discharge. This will be analyzed as a secondary outcome only if enough data is generated on chart review.
Time frame: Assessed up to 12 months from hospital discharge
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