Changes in coagulation during therapeutic hypothermia in cardiac arrest patients

Therapeutic hypothermia improves neurological outcome in patients resuscitated after out-of-hospital cardiac arrest. The aim was to investigate whether therapeutic hypothermia induced impaired coagulation.

Changes in coagulation were investigated in 22 out-of-hospital cardiac arrest patients treated with therapeutic hypothermia (33 ± 1 °C). Blood samples were obtained after 22 ± 2h of hypothermia and compared with normothermic samples drawn 48 h later. The coagulation was evaluated with thromboelastometry (ROTEM(®)) using a sensitive low-tissue-factor assay. Leukocytes, haemoglobin, haematocrit, platelet count, activated partial thromboplastin time (aPTT), thrombin time, international normalised ratio (INR) and fibrinogen were also measured. Clinical information including use of anti thrombotic drugs was systematically collected.

No significant changes were found in clotting time (p=0.21), clot formation time (p=0.26), time to maximum velocity (p=0.52) or maximum velocity (p=0.17) when results obtained at hypothermia were compared with results obtained at normothermia. Maximum clot firmness (p<0.01) and fibrinogen levels (p<0.01) were significantly higher in patients at normothermia. However, the fibrinogen levels were within the reference interval for all patients at both hypothermia and normothermia. Values of aPTT, thrombin time and INR at hypothermia and normothermia were not significantly different.

No substantial difference in coagulation was found in hypothermia compared with normothermia in out-of-hospital cardiac arrest patients. The results indicate that treatment with hypothermia does not impair coagulation.

NCT02179021.