Table 2

Author, date and country	Patient group	Study type (level of evidence)	Outcomes	Key results	Study weaknesses
Vretnar DF et al, 1994, Canada	68 hypothermic patients with a mean core temperature of 21°C of whom 61 were in cardiac arrest.	Review	Overall survival	60%	Publication bias likely as success more likely to be reported than failure.
	All patients placed on cardiopulmonary bypass		Survival if core temperature <15 degrees	0%
	Data derived from 34 reports.		Return to previous function	60% of survivors
Koller R et al, 1997, Switzerland	5 patients with core temperature below 30°C of whom 2 were in cardiac arrest	Cohort	Overall survival	100%	Small numbers.
			Return to previous function	100%
Walpoth BH et al, 1997	32 of 46 patients in cardiac arrest with core temperature below 28°C	Prospective cohort	Overall survival	15/32 (45%)	Unclear why patients selected for bypass
	All patients placed on cardiopulmonary bypass