Hyperthermia after cardiac arrest

In morning report today, we discussed the brain death exam and the apnea test. A theoretical case was discussed, noting the occurrence of pyrexia after arrest and its relation to neurologic sequelae. Research indicates that hyperthermia after arrest portends a poor prognosis, independent of infection. According to the 2010 AHA CPR guidelines, this may be due to the elevation of inflammatory cytokines, similar to sepsis (1). Early trials indicate that hyperthermia after cardiac arrest may be associated with the outcome of brain death (2), possibly due to dysregulation of temperature control centers.

Takino et. al. “analyzed the hyperthermia (above 38°C) occurring in the initial 48 h after resuscitation. After resuscitation, most patients showed a rapid rise in body temperature. Patients with later brain death showed significantly earlier appearance of hyperthermia (6.2 h after cardiac resuscitation; median) and a higher peak temperature (39.8°C; median) compared with patients showing prolonged coma (12.7 h and 38.3°C, respectively). Hyperthermia above 39°C was associated with subsequent brain death. The incidence of factors influencing body temperature did not differ between the brain death and prolonged coma groups. Patients achieving full recovery did not show hyperthermia. [They] analyzed the hyperthermia (above 38°C) occurring in the initial 48 h after resuscitation. After resuscitation, most patients showed a rapid rise in body temperature. Patients with later brain death showed significantly earlier appearance of hyperthermia (6.2 h after cardiac resuscitation; median) and a higher peak temperature (39.8°C; median) compared with patients showing prolonged coma (12.7 h and 38.3°C, respectively). Hyperthermia above 39°C was associated with subsequent brain death. The incidence of factors influencing body temperature did not differ between the brain death and prolonged coma groups. Patients achieving full recovery did not show hyperthermia (3).”

Additionally, as patients become hyperthermic, the difference between brain and core temperature increases, which may indicate that the true incidence of febrile episodes in the brain is even higher than that reported in large observational studies that measured only core body temperature (4). Hyperthermia causes the release of excitatory amino acids and free radicals, aggravates blood-brain barrier breakdown, amplifies cytoskeletal proteolysis, promotes acidosis, and increases cerebral metabolic rate (4, 5). In conclusion, hyperthermia is an early indicator of brain damage after resuscitation (3).

1. Circulation. 2010; 122: S768-S786

2. Resuscitation. 2001 Jun;49(3):273-7.

3. Intensive Care Med. 1991;17(7):419-20.

4. Anesthesiology Research and Practice. Volume 2012 (2012), Article ID 989487, 13 pages.

5. Critical Care 2012, 16(Suppl 2):A2