Survival does not improve when therapeutic hypothermia is added to post-cardiac arrest care

We investigated whether the use of therapeutic hypothermia improves the outcome after cardiac arrest (CA) under routine clinical conditions.

In a retrospective study, data of CA survivors treated from 2003 to 2010 were analysed. Of these, 143 patients were treated with hypothermia at 33 ± 0.5°C for 24h according to predefined inclusion criteria, while 67 who did not fulfil these criteria received comparable therapy without hypothermia.

210 patients were included, 143 in the hypothermia group (HG) and 67 in the normothermia group (NG). There was no significant difference in mortality between the groups; 69 (48.2%) in the HG died in the first four weeks, compared to 30 patients (44.8%) in the NG (p=0.659). Patients in the NG were older and more seriously ill, and CA occurred more often in-hospital. Binary logistic regression revealed ventricular fibrillation (p=0.044), NSE serum level < 33 ng ml⁻¹ (p<0.001), age (p=0.035) and witnessed cardiac arrest (p=0.043) as independent factors significantly improving survival after CA, whereas hypothermia was not (p=0.69). The target temperature was maintained for a significantly longer time (19.5h vs. 15.2h; p=0.003) in hypothermia patients with a favourable outcome than in those with an unfavourable outcome.

There was no improvement in survival rates when hypothermia was added to standard therapy in this case series, as compared to standard therapy alone. The time at target temperature may be of relevance. We need better evidence in order to expand the recommendations for hypothermia after CA.