Skip to main content

Targeted Temperature Management

Question# 793

What is RPPEO's direction on prehospital therapeutic hypothermia for ROSC patients? There is research that supports this practice for suspected cardiac-origin cardiac arrest patients and is, in fact, listed in the OHI/TOH ED "Code ROSC Pathway."

Answer:

Targeted temperature management (a temperature of 32°C and 36°C for at least 24 hours) has been shown to improve survival in patients successfully resuscitated after a cardiac arrest. In fact, TTM is strongly (Class 1) recommended by the AHA.

It’s hypothesized that initiating TTM reduces the body’s metabolic demands, by decreasing the ischemia–reperfusion response, decreasing the permeability of the blood–brain barrier, and improving cerebral microcirculation thus optimizing brain recovery and avoiding secondary injuries. Cerebral metabolism is also reduced by approximately 6% to 10% for every 1C decrease in core temperature during the cooling period.

While there is no consensus amongst the major guidelines (AHA, ERC, American Academy of Neurology, Canadian Critical Care Society) with respect to what temperature should be aimed for, the most important principle suggests preventing hyperthermia (rather than inducing hypothermia), as fever is common in the postarrest period, and the risk of an unfavorable neurologic outcome increases with every degree higher than 37C.

While cooling should also be started as soon as possible after ROSC, as the beneficial effects are understood to decrease with delayed initiation, given the complexity, TTM is not something that should be undertaken prehospitally. Paramedics have no way to accurately assess core body temperature, nor do they have the tools to initiate cooling. As a corollary, one of the risks and challenges to TTM is shivering, as it will increase the body’s temperature, and the treatment – deep sedation and paralytics – obviously cannot be performed in the prehospital arena. Lastly, cooling is also resource heavy, and takes away from the other timely, life-saving prehospital interventions.

Moreover, a 2015 systematic review found that prehospital cooling with the specific method of the rapid infusion of cold IV fluids was associated with more pulmonary edema and a higher risk of rear-arrest. Further studies looking at prehospital TTM also do not seem to have an impact on survival, thus the evidence does not support the early routine use of prehospital temperature management.

Providing effective care in the postarrest period is a challenging endeavor, and prehospitally, we should be focusing on the interventions we can positively impact:
  • Immediate 12-lead ECG to determine if the patient needs PCI
  • Maintain oxygenation and an SpO2 94-98%. Hypoxia is dangerous in the postarrest period, but there are also risks to hyperoxia.
  • Maintain ventilation (EtCO2 30-40 mmHg) to help optimize cerebral blood flow. Hypocapnia secondary to hyperventilation can lead to cerebral ischemia and has been associated with increased mortality in the postarrest patient. Conversely, hypercapnia can dilate cerebral blood vessels and improve cerebral blood flow.
  • Maintain a mean arterial pressure of at least 65 mmHg. Hypotension has been consistently associated with increased mortality and must be avoided and agressive hemodynamic management can help prevent rearrest. Having a liberal use of fluids and/or dopamine would be a good strategy.
To summarize, TTM should not be initiated prehospitally, and we should focus our interventions on the immediate physiological needs of the critically ill patient in front of us.

If you’re interested in learning more about ROSC management, we suggest you visit https://mediclearn.rppeo.ca, then search "ROSC" – this is a podcast with ICU MD Dr. Kwadwo Kyeremanteng.

Also, if you’re interested in learning more about high performance cardiac arrest management, we suggest you visit https://mediclearn.rppeo.ca and search "High Performance Cardiac Arrest Management" to listen to one of our elective CMEs.

References

2020 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care
Lüsebrink, E., Binzenhöfer, L., Kellnar, A., Scherer, C., Schier, J., Kleeberger, J., Stocker, T. J., Peterss, S., Hagl, C., Stark, K., Petzold, T., Fichtner, S., Braun, D., Kääb, S., Brunner, S., Theiss, H., Hausleiter, J., Massberg, S., & Orban, M. (2022). Targeted Temperature Management in Postresuscitation Care After Incorporating Results of the TTM2 Trial. Journal of the American Heart Association, 11(21), e026539. https://doi.org/10.1161/JAHA.122.026539
Reardon, P. M., Hickey, M., English, S. W., Hibbert, B., Simard, T., Hendin, A., & Yadav, K. (2020). Optimizing the Early Resuscitation After Out-of-Hospital Cardiac Arrest. Journal of intensive care medicine, 35(12), 1556–1563. https://doi.org/10.1177/0885066619873318

Published

04 April 2024

ALSPCS Version

5.3

Views

139

Please reference the MOST RECENT ALS PCS for updates and changes to these directives.