Postcardiac Arrest Therapeutic Hypothermia Clinical Trial
Official title:
Post-arrest Therapeutic Hypothermia. Does Use of Neuromuscular Blockers Achieve Faster Cooling Time?
After successful resuscitation from cardiac arrest, cooling the whole body is a well
established treatment that improves the chances of the brain recovering. This however, has
to be done within a certain time-frame from the arrest. The purpose of this study is to
explore the best way of dosing the muscle relaxing medications that are given during the
cooling process.
Hypothesis: In the context of our institutional therapeutic hypothermia protocol,
cisatracurium infusions lead to faster drops in core temperature when compared to
cisatracurium prn boluses alone.
STUDY RATIONALE:
A large proportion of comatose survivors of cardiac arrest presenting to our intensive care
units at London Health Sciences Centre (LHSC) undergo therapeutic hypothermia. Current
evidence suggests that timely achievement of target temperatures is desirable to improve
outcomes. At LHSC, this intervention is protocolized with a defined set of preprinted orders
that includes a dosing regimen for neuromuscular blocking agents (NMBA's). Our preprinted
protocol has been in place since January of 2004. Cisatracurium infusions were part of the
therapeutic hypothermia protocol until October 2011. Since that time, our protocol has
changed to cisatracurium prn boluses for any observed shivering. In this study we will
examine if there has been any change in the times to achieving target temperatures with the
implementation of this change. It is important to note that no other change in our protocol
has taken place since it was first implemented, making our before and after comparison valid
and fair.
Our hypothesis is that NMBA infusions lead to a faster drop in core temperatures when
compared to NMBA prn boluses. If this were to stand true, we would expect cisatracurium IV
infusions to result in faster reductions in core temperature when compared with
cisatracurium prn boluses in the context of our therapeutic hypothermia protocol.
Hypothermia has been known to cause a subclinical increase in muscle tone. This previously
reported phenomenon has been named "microshivering". When attempting to reduce core
temperatures, microshivering is likely a natural body response to try to restore body
temperature back to normal. We therefore hypothesize that NMBA infusions are likely more
effective at abolishing microshivering, which would be a desirable effect when trying to
induce therapeutic hypothermia.
Although current American Heart Association (AHA) guidelines suggest considering the
administration of NMBA's to facilitate induced hypothermia and control shivering. Their
recommendation is to minimize the duration of NMBA use or if possible, avoid them
altogether. After the publication of these guidelines our institutional protocol changed to
prn boluses instead of the previous infusion orders. We therefore believe it is important to
examine the effects of this change on our cooling protocol and potentially add to the
growing body of knowledge in this field.
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Observational Model: Cohort, Time Perspective: Retrospective