Revised version of Hypothermia Flowchart

Please note : There is an updated June 2021 version of the flowchart, version 4. If you enter that in the search box, you will find it. Cheers,Malin 

I am really excited to tell you that Dr Les Gordon , who has co-authored  several research papers on the management of accidental hypothermia, has kindly peer reviewed my flowchart. I emailed him saying how much I had enjoyed his and Peter Paal’s article

Managing accidental hypothermia progress but some way to go

I cheekily added a paragraph about my research and my  flowchart and he replied with great enthusiasm and support for my work which made me full of joy! I am very grateful for the time he spent  and the valuable suggestions he made. He expresses it much more eloquently than I am able to myself , so the following paragraph is copied from his email:

• “I assume that the advice not to allow patients with mild hypothermia not too walk for 30 minutes after food and drink comes from the 2014 Wilderness Medical Society guidelines because of the concerns about afterdrop (the continued fall in core temperature following removal from the cold and application of insulation). It’s important to understand the mechanism underpinning this. Afterdrop will occur if there is increased blood flow to cooler tissues with exercise (called the ‘convective’ theory of afterdrop). Exercising muscles will eventually produce a lot of heat, but there will be a lag before this heat is available, and it is during this period that afterdrop will occur because the initial blood returning to the central circulation will have been cooled by the cold muscles. Shivering and external heat reduce the amount and duration of afterdrop because these modalities rewarm the tissues directly so that blood flowing out of them is not as cool as it otherwise would be. Because of this, afterdrop is only a risk if the casualty’s core temperature is in the low 30’s (i.e. bordering on moderate hypothermia), because in that situation, a further fall of a couple of degrees will bring the cardiac temperature into the upper 20’s where the risk of cardiac arrest increases. But if the casualty’s temperature is about 34-35°C, then afterdrop will still occur but it is not a risk because a fall of 2°C will only take the core down to 32-33°C, which is not a risk for cardiac arrest. This distinction is more than academic because in remote locations, rescuers may not have the luxury of being able to wait for 30 minutes before trying to get the casualty to walk out. Importantly, as pointed out in a follow-up letter after the guidelines were published, there have been no case reports in which exercise-induced afterdrop has caused cardiac instability in true mild hypothermia. The relevant papers about this are listed at the end of my email. The one that particularly led to the WMS recommendation is Giesbrecht, 1998.” ( all of Les’s recommended references are at the bottom of this post)

I have decided to remove the “do not allow casualty to stand or walk until 30 minutes after food & drink” from the Mild Hypothermia category.

I have bolded the “If injured MUST have active heat added to help reduce coagulopathy (deranged clotting) below 34*C” in the Mild Hypothermia category

I considered adding a similar sentence to the Cold Stress Category, maybe I should?  This flowchart is designed as  a cognitive aid to be used  in time of stress, it is not an educational resource. The  accompanying (updated)

Explanatory notes to Hypothermia flowchart, October 2018

should be read in advance and practical training of the concept should be carried out prior to using the flow chart. I feel that during  practical training  is where Trauma Induced Hypothermia and all its’  “lethal triad” complications should be addressed in order to achieve good understanding and adherence to preventative measures.

I have increased the longest successful CPR with intact neurological outcome from 6 hours to 9 hours as per this article

Hypothermic cardiac arrest with full neurologic recovery after 9 hours of cardiopulmonary resuscitation: Management and possible complications

These are all the revisions for now (October 2018). I will post each successive revision here , please make sure you always the current version. (Well, if ICAR can do it for their Avalanche victim resuscitation checklist, so can I, right? : )  )

Cheers for now,

Malin

SOME REFERENCES ( these are Dr.  Les Gordon’s recommended references )

Afterdrop: definition

• Haverkamp FJC, Giesbrecht GG, Tan ECTH. The prehospital management of hypothermia – An up-to-date overview. Injury 2018;49:149-64.
• Tipton MJ, DucharmeMB. Rescue collapse following cold water immersion. In: Bierens JJ, editor. Drowning Prevention, Rescue, Treatment edn. Berlin: Springer; 2014. p. 855–8.

Afterdrop – factors affecting

• Giesbrecht GG, Bristow GK. The convective afterdrop component during hypothermic exercise decreases with delayed exercise onset. Aviat Space Environ Med1998;69(1):17–22.
• Giesbrecht GG, Goheen MS, Johnston CE, Kenny GP, Bristow GK, Hayward JS. Inhibition of shivering increases core temperature afterdrop and attenuates rewarming in hypothermic humans. J Appl Physiol 1997;83(5):1630–4.
• Lundgren JP, Henriksson O, Pretorius T, Cahill F, Bristow G, Chochinov A, et al. Field torso-warming modalities: a comparative study using a human model. Prehosp Emerg Care2009;13(3):371–8. doi:10.1080/10903120902935348.
• Hultzer M, Xu X, MarraoC, Bristow GK, Chochinov A, Giesbrecht GG. Pre-hospital torso-warming modalities for severe hypothermia: a comparative study using a human model. Can J Emerg Med2005;7:378–86.
• Giesbrecht GG, Bristow GK, Uin A, Ready AE, Jones RA: Effectiveness of three field treatments for induced mild (33.0°C) hypothermia. J Appl Physiol 1987;63:2375-79.
• Giesbrecht GG, Bristow GK. A second post cooling after drop: more evidence for a convective mechanism. J Appl Physiol 1992;73(4):1253–8.

Hypothermia in the presence of trauma – redefined temperature ranges and the physiological implications of hypothermia in the presence of trauma

• Gentilello LM. Advances in the management of hypothermia. Surg Clin North Am. 1995;75:243–256.
• Shafi S, Elliott AC, Gentilello L. Is hypothermia simply a marker of shock and injury severity or an independent risk factor for mortality in trauma patients? Analysis of a large national trauma registry. J Trauma 2005;59:1081-5
• Jurkovich GJ. Environmental cold-induced injury. Surg Clin N Am 2007;87:247-67
• Nesbitt M, Allen P, Beekley A, et al. Current practice of thermoregulation during the transport of combat wounded. J Trauma 2010;69:S162-7
• Bennett BL, Holcomb JB. Battlefield trauma-induced hypothermia: Transitioning the preferred method of casualty rewarming. Wild Environ Med 2017;28:S82-9

And these are the articles Dr Les Gordon has co authored:

Dr Les Gordon on Researchgate