A review on targeted temperature management for cardiac arrest and traumatic brain injury

Abstract

Therapeutic hypothermia inhibits organ damage by suppressing metabolism, which makes it a therapy of choice for treating various diseases. Specifically, it is often used to treat conditions involving central nervous system disorders where it is expected to positively impact functional prognosis. Although keeping the body temperature at a hypothermic level has been conventionally used, how to manage the body temperature correctly remains a topic of debate. Recently, the concept of temperature management has been proposed to improve the quality of body temperature control and avoid hyperthermia. This review focuses on the effect of temperature on the central nervous system in conditions involving central nervous system disorders and the practice of temperature management in clinical situations.

Keywords: body temperature; cardiac arrest; central nervous system; head injury; hypothermia.

Figure 1

Mechanism of brain damage in head injury and cardiac arrest and effects of temperature management. Brain damage is a consequence of the head injury. This damage triggers the release of inflammatory cytokines. In addition, damage to the hypothalamus causes the body’s thermoregulatory system to fail. These factors have a systemic impact, resulting in fever. Systemic fever results in the production of thermogenic substances such as prostaglandin E2 (PGE2). Infectious complications can also cause fever and stimulate the production of inflammatory cytokines. These thermogenic substances and cytokines cross the damaged blood–brain barrier (BBB) and affect neurons. In cardiac arrest, cerebral blood flow is impaired and cell membrane depolarization occurs. This leads to cell swelling and destruction. As part of the inflammatory response, oxygen free radicals are also produced, resulting in mitochondrial dysfunction and further progression of neuronal necrosis and apoptosis. Reperfusion can further exacerbate central nervous system damage, leading to secondary superoxide surges, increased nitric oxide production, alterations in BBB permeability, cerebral edema, cerebral hemorrhage, and apoptosis. Temperature management is believed to reduce brain damage by mitigating mitochondrial dysfunction and apoptosis. TTM, targeted temperature management.