Table 1 Comparison of two recent trials of hypothermia in cardiac arrest
| Â | Â | Trial | |
|---|---|---|---|
Study information and statistical significance | European [1] | Australian [2] | |
Type of study | Randomized: normothermia versus hypothermia | Randomized: normothermia versus hypothermia | |
| Â | Â | Multicentered, with nine centers in five countries | Four accepting emergency departments |
| Â | Â | Blinded outcome | Not blinded for treatment or outcome |
Number of patients | 275 Total | 77 Total | |
| Â | Â | 138 Normothermia | 34 Normothermia |
| Â | Â | 137 Hypothermia | 43 Hypothermia |
Criteria | Inclusion | Witnessed arrest | Initial rhythm VF |
| Â | Â | Arrest secondary to VF | Continued coma after ROSC |
|  |  | Age 18–75 years | Age: women >50 years; men >18 years |
| Â | Â | <60 min to ROSC | Â |
|  | Exclusion | Temp <30°C | Cardiogenic shock (SBP <90 mmHg despite epinephrine) |
| Â | Â | Coagulopathy | Â |
| Â | Â | Pregnant | Pregnant |
| Â | Â | Awake before randomization | Other causes of coma |
| Â | Â | MAP <60 mmHg for >30 min | ICU bed unavailable |
| Â | Â | Hypoxemia for >15 min | Â |
| Â | Â | Terminal illness | Â |
| Â | Â | Unavailable for follow-up | Â |
| Â | Â | Enrolment in other study | Â |
Comparability of hypothermia and normothermia groups | The normothermia group had higher rates of coronary artery disease and diabetes mellitus | The normothermia group had a higher percentage of bystander-performed cardiopulmonary resuscitation | |
Cooling | Temperature used | 32–34°C (bladder temperature) | 33°C |
| Â | Mechanism | Cool air circulating device and ice packs | Ice packs |
|  | Time to start | Mean 105 min | Cooling began prehospital at a rate of 0.9°C/hour |
| Â | Duration | 24 hours | 12 hours |
Rewarming | Â | Passive over 8 hours | Passive |
Side effects | Â | No statistical difference between the two groups | No statistical difference between the two groups |
End-points | Primary | Favorable neurologic outcome at 6 months after arrest | Discharge to home or rehabilitation |
| Â | Secondary | (1) Mortality within 6 months | Side effects of hemodynamic, biochemical, or hematological instability |
| Â | Â | (2) Complications within 7 days | Â |
Outcomes | Â | Hypothermia: favorable outcome in 75 patients (55%) | Hypothermia: favorable outcome in 21 patients (49%) |
| Â | Â | Normothermia: favorable outcome in 54 patients (39%) | Normothermia: favorable outcome in 9 patients (26%) |
Statistical significance of the outcomes | P = 0.009 | P = 0.046 | |