What are the guidelines for temperature management in hospitalized patients post-cardiac arrest (cardiac arrest)?

From the Guidelines

Temperature management for hospitalized patients after cardiac arrest should focus on targeted temperature management (TTM) to improve neurological outcomes, with a strong recommendation to maintain a constant target temperature between 32°C and 36°C for at least 24 hours in comatose patients following return of spontaneous circulation 1.

Key Recommendations

• The current guidelines suggest selecting and maintaining a constant target temperature between 32°C and 36°C for those patients in whom temperature control is used, with a strong recommendation for adults with out-of-hospital cardiac arrest (OHCA) with an initial shockable rhythm who remain unresponsive after return of spontaneous circulation (ROSC) 1.
• TTM is also suggested for adults with OHCA with an initial nonshockable rhythm who remain unresponsive after ROSC, as well as for adults with in-hospital cardiac arrest (IHCA) with any initial rhythm who remain unresponsive after ROSC, although the evidence for these recommendations is weaker 1.
• The results of the HYPERION trial support the use of TTM, targeting a constant temperature between 32°C and 36°C in patients who remain comatose after resuscitation from either IHCA or OHCA with an initial nonshockable rhythm 1.

Implementation

• Cooling should begin as soon as possible after the arrest, using either external cooling methods (cooling blankets, ice packs) or internal methods (cold saline infusion, intravascular cooling catheters).
• Core temperature should be continuously monitored via esophageal, bladder, or intravascular probes.
• Patients require sedation (typically propofol 5-50 mcg/kg/min or midazolam 0.02-0.1 mg/kg/hr) and often neuromuscular blockade (cisatracurium 0.15-0.2 mg/kg bolus followed by 1-2 mcg/kg/min infusion) to prevent shivering.
• After the maintenance period, rewarming should occur slowly at 0.25-0.5°C per hour to avoid rebound hyperthermia.
• For at least 72 hours post-arrest, even after the TTM period, temperature should be actively controlled to prevent fever (temperature >37.5°C), as hyperthermia is associated with worse neurological outcomes.

Rationale

• TTM works by reducing cerebral metabolic demands, decreasing free radical production, and limiting the inflammatory cascade that contributes to secondary brain injury after cardiac arrest.
• The use of TTM has been shown to improve neurological outcomes in comatose patients after cardiac arrest, with a significant reduction in mortality and improvement in cognitive function 1.

From the Research

Guidelines for Temperature Management

• The optimal target core temperature for targeted temperature management (TTM) in patients with post-cardiac arrest syndrome (PCAS) due to cardiac etiology is still a topic of debate, with some studies suggesting a temperature of 34 °C or 35 °C 2.
• The International Liaison Committee on Resuscitation Advanced Life Support Task Force recommends targeted temperature management for adults with out-of-hospital cardiac arrest with an initial shockable rhythm at a constant temperature between 32 °C and 36 °C for at least 24 hours 3.
• The American Heart Association also suggests that targeted temperature management be used in comatose post-cardiac arrest patients, with a goal temperature of 32 °C-36 °C for at least 24 hours 3.

Duration and Timing of Temperature Management

• The duration of cooling is also an important factor, with some studies suggesting a duration of 24 hours 2, 3 and others suggesting 48 hours 2.
• The timing of the intervention is also crucial, with some studies suggesting that earlier initiation of TTM may be beneficial 4.
• A study found that the time-in-therapeutic range (TTR) for TTM between 32 °C-36 °C was associated with favorable neurologic outcome, but not overall survival 5.

Target Temperature Range

• The target temperature range for TTM is generally considered to be between 32 °C and 36 °C 3, 4, 5.
• Some studies have compared the effectiveness of different target temperatures, such as 33 °C versus 36 °C, and found no significant difference in outcomes 6.
• However, another study found that a target temperature of 33 °C-36 °C was associated with favorable neurologic outcome 5.