The intervention decreased mean core temperature by 1.20 C ( 95 % CI , -1.33 C to -1.07 C ) in patients with VF and by 1.30 C ( 95 % CI , -1.40 C to -1.20 C ) in patients without VF by hospital arrival and reduced the time to achieve a temperature of less than 34C by about 1 hour compared with the control group .