Uptake of therapeutic hypothermia following out-of-hospital cardiac arrest in Scottish Intensive Care Units

Intra-arrest hypothermia during cardiac arrest: a systematic review

Introduction

Therapeutic hypothermia is largely used to protect the brain following return of spontaneous circulation (ROSC) after cardiac arrest (CA), but it is unclear whether we should start therapeutic hypothermia earlier, that is, before ROSC.

Methods

We performed a systematic search of PubMed, EMBASE, CINAHL, the Cochrane Library and Ovid/Medline databases using "arrest" OR "cardiac arrest" OR "heart arrest" AND "hypothermia" OR "therapeutic hypothermia" OR "cooling" as keywords. Only studies using intra-arrest therapeutic hypothermia (IATH) were selected for this review. Three authors independently assessed the validity of included studies and extracted data regarding characteristics of the studied cohort (animal or human) and the main outcomes related to the use of IATH: Mortality, neurological status and cardiac function (particularly, rate of ROSC).

Results

A total of 23 animal studies (level of evidence (LOE) 5) and five human studies, including one randomized controlled trial (LOE 1), one retrospective and one prospective controlled study (LOE 3), and two prospective studies without a control group (LOE 4), were identified. IATH improved survival and neurological outcomes when compared to normothermia and/or hypothermia after ROSC. IATH was also associated with improved ROSC rates and with improved cardiac function, including better left ventricular function, and reduced myocardial infarct size, when compared to normothermia.

Conclusions

IATH improves survival and neurological outcome when compared to normothermia and/or conventional hypothermia in experimental models of CA. Clinical data on the efficacy of IATH remain limited.

Therapeutic hypothermia after cardiac arrest - implementation in UK intensive care units

A telephone survey was carried out to determine how many United Kingdom intensive care units were using therapeutic hypothermia as part of their management of unconscious patients admitted after cardiac arrest. All 247 intensive care units listed in the 2008 Directory of Critical Care Services were contacted to determine how many units were using hypothermia as part of their post-cardiac arrest management and how it was implemented. We obtained information from 243 (98.4%) of the intensive care units. At the time of the study, 208 (85.6%) were using hypothermia as part of post-cardiac arrest management. There has been a steady increase annually in the number of units performing therapeutic cooling from 2003 to date, with the majority of units starting in 2007 or 2008. The International Liaison Committee on Resuscitation guidelines, which recommend the use of therapeutic hypothermia for comatose patients following successful resuscitation from cardiac arrest, have taken at least 4-5 years to achieve widespread implementation in the United Kingdom.