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One of the most controversial topics in resus causing sighs all round...targeted temperature management! Why is it so controversial? Lets explore the science behind it, the papers that have shaped our understanding and the current recommendations with @Dr_JRogers #ResusciTuesdays
Before reading this tweetorial a little poll: Do you use TTM in your work setting for unresponsive patients post ROSC who meet the criteria?
Neuro injury from cerebral hypoxia is the most common cause of OHCA death. Post-resus care has changed dramatically to combat this. Survival to hospital discharge worldwide is only 8%. A period of hyperpyrexia in first 48hrs is common and many studies link this to poor outcomes
As far back as Hippocrates there was an understanding that the use of snow and ice could reduce haemorrhage in bleeding patients
1954: 26-35oC in animal models may play a role in anoxic brain injury prevention by reducing brain tissue metabolism
https://pubmed.ncbi.nlm.nih.gov/13207391/
1954: 26-35oC in animal models may play a role in anoxic brain injury prevention by reducing brain tissue metabolism
https://pubmed.ncbi.nlm.nih.gov/13207391/
1958: first human study of hypothermia after cardiac arrest, temp of 31-32oC for up to 84h for those patients in asystole or VF. Survival improved from 14% to 50% (but was only performed on 19 patients) https://pubmed.ncbi.nlm.nih.gov/13798997/
1999: cooling suppresses apoptosis and CMRO2 leading to reduced free radicals and inflammatory response
https://pubmed.ncbi.nlm.nih.gov/16554254/
2002: RCTs show improved neuro recovery if cooled 32-34oC for 24 hours https://www.nejm.org/doi/full/10.1056/nejmoa012689
https://pubmed.ncbi.nlm.nih.gov/16554254/
2002: RCTs show improved neuro recovery if cooled 32-34oC for 24 hours https://www.nejm.org/doi/full/10.1056/nejmoa012689
2005: TTM in @ERC_resus guidelines for initial 24h post arrest but w/o a protocol. Many continue to avoid TTM as
had insufficient knowledge of effective techniques, lack of belief it improved outcome and controversies around best method to reach targets
https://pubmed.ncbi.nlm.nih.gov/16324987/
had insufficient knowledge of effective techniques, lack of belief it improved outcome and controversies around best method to reach targets
https://pubmed.ncbi.nlm.nih.gov/16324987/
2010: @Ilcor_org recommends TTM if comatose post ROSC after VF OHCA with rapid infusion ice cold IV fluids
https://pubmed.ncbi.nlm.nih.gov/20956256/
2010: @AHAScience recommend TTM for post-resus bundle in any rhythm IHCA/OHCA https://pubmed.ncbi.nlm.nih.gov/11525703/
https://pubmed.ncbi.nlm.nih.gov/20956256/
2010: @AHAScience recommend TTM for post-resus bundle in any rhythm IHCA/OHCA https://pubmed.ncbi.nlm.nih.gov/11525703/
The most common methods at this time were ice-cold IV fluids or application of ice packs. These can be time consuming and have large fluctuations as they are uncontrolled. After that; cooling blankets, pads and IV heating exchangers took off. The newest method being used is ECMO
Don’t forget NM blockade and sedation to prevent shivering but remember clearance of these drugs reduces by 30% at temp of 34oC. Magnesium can also reduce the shivering threshold
2013: TTM trial https://www.nejm.org/doi/full/10.1056/nejmoa1310519 shows no benefit of 33oC vs <36oC with good outcome in both groups. However there’s ↑ likelihood of bradycardia, ↑ lactate + ↑ vasopressors needed with lower temps. This reconfirms how important the avoidance of hyperthermia is, but...
many physicians took this to mean cooling was inefficient. Here is where we really started to see declines in active cooling with anti-hyperthermic measures (e.g Paracetamol) used instead! Is this really what the study showed?
Did you change your practice based on the TTM trial?
Did you change your practice based on the TTM trial?
2014: large RCT looked at cooling pre-hospitally with 2L of 4oC saline: greatly ↓ time to cool, but didn’t improve outcomes and lead to more re-arrest en route and pulmonary oedema requiring diuresis https://pubmed.ncbi.nlm.nih.gov/24240712/
2015: ERC target <36oC and ILCOR 32-36oC for 24h.
https://ercguidelines.elsevierresource.com/european-resuscitation-council-and-european-society-intensive-care-medicine-guidelines-post/abstract
The current ERC 2015 guidelines say that although TTM remains important, there is now an option to target 36oC instead of the previous 32-34oC
https://ercguidelines.elsevierresource.com/european-resuscitation-council-and-european-society-intensive-care-medicine-guidelines-post/abstract
The current ERC 2015 guidelines say that although TTM remains important, there is now an option to target 36oC instead of the previous 32-34oC
ERC: Maintain a constant target temp 32-36oC although some populations may benefit from either end of the spectrum (more research needed)
TTM is recommended in adults after OHCA and IHCA with initial shockable and non-shockable rhythms who remain unresponsive after ROSC
TTM is recommended in adults after OHCA and IHCA with initial shockable and non-shockable rhythms who remain unresponsive after ROSC
If used, aim for at least 24hrs. Whichever temp is picked, active control is required. If the patient is below 36oC on arrival, they can be allowed to rewarm spontaneously but a cooling device should be ready for when they reach 36oC
2017: TTM 48 trial no difference if cooled for 48 vs 24 hours but longer ICU stay in 48 group. However it had limited power https://pubmed.ncbi.nlm.nih.gov/28742911/
Physiological effects of TTM: shivering increases metabolic + heat production so ↓ cooling rates. Mild hypothermia increases SVR -> arrhythmias – bradycardia may be beneficial in reducing diastolic dysfunction. Watch out for diuresis and hypoPhos/Mg/K/Ca
Hypothermia ↓ insulin sensitivity and secretion -> hyperglycaemia. It also impairs coagulation and may cause some minor bleeding. It can impair the immune system and ↑ infection rates
#donteverforgetglucose
#donteverforgetglucose
Contraindications: severe systemic infection, pre-existing medical coagulopathy and cardiogenic shock but these are not adhered to universally.
With the ERC 2021 guidelines coming in March, we will revisit this thread with an update when they’re published!
With the ERC 2021 guidelines coming in March, we will revisit this thread with an update when they’re published!
Thanks for sticking with us through that deep dive! After reading the tweetorial: Would you now use TTM in all relevant cases when unresponsive post ROSC?
#ResusciTuesdays #resus #TTM
#ResusciTuesdays #resus #TTM
