From the Guidelines
Therapeutic hypothermia, now more accurately referred to as targeted temperature management (TTM), is still recommended post Return of Spontaneous Circulation (ROSC) for comatose adult patients, with a target temperature between 32°C and 36°C maintained for at least 24 hours. This approach is based on the most recent and highest quality evidence available, as outlined in the 2015 American Heart Association guidelines update for cardiopulmonary resuscitation and emergency cardiovascular care 1. The recommendation emphasizes the importance of TTM in improving outcomes for comatose patients after cardiac arrest, with a focus on maintaining a constant temperature within the specified range to minimize the risk of secondary brain injury.
Key Recommendations for TTM
- Maintain a target temperature between 32°C and 36°C for comatose adult patients after ROSC 1.
- TTM should be maintained for at least 24 hours after achieving the target temperature 1.
- Selecting and maintaining a constant temperature within the recommended range is crucial, with evidence supporting a Class I, LOE B-R recommendation for this approach 1.
- The use of sedation, such as propofol or midazolam, and neuromuscular blockade, like cisatracurium, may be necessary to prevent shivering and maintain the target temperature 1.
Implementation and Monitoring
- Core temperature should be continuously monitored using esophageal, bladder, or central venous temperature probes to ensure accurate temperature management.
- Active temperature management using external cooling devices or cold saline infusion may be employed to achieve and maintain the target temperature.
- Gradual rewarming at 0.25-0.5°C per hour is recommended after the maintenance period to avoid hemodynamic instability.
Rationale and Benefits
The primary mechanism of benefit for TTM appears to be the prevention of secondary brain injury by reducing cerebral metabolic demands, inflammation, and free radical production during the critical post-arrest period. By maintaining a target temperature between 32°C and 36°C, TTM aims to balance the neuroprotective benefits of preventing hyperthermia while avoiding complications associated with more aggressive cooling strategies. This approach is supported by the 2015 guidelines, which emphasize the importance of TTM in improving outcomes for comatose patients after cardiac arrest 1.
From the Research
Current Recommendations for Therapeutic Hypothermia
The current guidelines for therapeutic hypothermia, also known as targeted temperature management (TTM), have undergone changes in recent years. According to 2, the term "therapeutic hypothermia" has been replaced by "targeted temperature management" and more recently by "temperature control" due to new evidence suggesting similar neuroprotective effects of different temperature targets.
Efficacy of Therapeutic Hypothermia
The efficacy of therapeutic hypothermia is still a topic of debate. A study published in 3 found that TTM was beneficial for patients with a collapse to ROSC time of 20-40 minutes, but not for those with shorter or longer times. Another study 4 found that rapid cooling was associated with improved outcomes, but the optimal timing and temperature target are still unclear.
Recent Developments and Controversies
Recent studies have highlighted the importance of temperature control in post-resuscitation care. A study published in 5 found that a post-ROSC normothermia bundle improved quality of care and clinical outcomes, while another study 6 recommended targeted temperature management for all rhythms and locations of cardiac arrest, with a temperature target between 32°C and 36°C for at least 24 hours.
Key Points
- Therapeutic hypothermia is still recommended for post-ROSC patients, but the optimal temperature target and timing are unclear 3, 4, 2.
- Targeted temperature management is a key measure in post-resuscitation care, with a recommended temperature target between 32°C and 36°C for at least 24 hours 6.
- Temperature control is important to prevent rebound hyperthermia and improve neurological outcomes 5, 6.
- The efficacy of therapeutic hypothermia is still a topic of debate, with some studies suggesting benefits and others finding no significant difference in outcomes 3, 4, 2.