Category Archives: cold

Do they really have to be “warm and dead”?

The classic teaching is that nobody is dead until they are warm and dead. But as discussed last week, knowing which patients are likely to survive (and thus warrant lifesaving efforts) is difficult to ascertain. Unlike the avalanche patient who is hypothermic, the non-trauma accidental hypothermia patient typically has better outcomes as well. It’s especially hard to stop (or not start) when you consider that the authors of this study had previously reported successful ROSC in a patient who had a core temp of 13.7◦C after 6 hours and 52 minutes of resuscitation.

The study was done in northern Norway, where data collection is easier for a hypothermia study. They had 28 years of data that they broke down into 3 “eras”; the early years, after moving to the new hospital, and post ECLS. Unfortunately, they only included 34 patients in their analysis, 9 of which survived. The authors did not find statistically significant difference in survival based on mechanism of cooling, season, initial ECG-rhythm, transport time, or distance from the medical center.

Similar to the French study, the potassium level was significantly different between survivors and non-survivors. Specifically, the highest level for survivors was 5.9 mmol/L, but a normal K did not predict survival. Survivors and non-survivors also differed in length of stay, as would be expected. However, the longest stay for a non-survivor was 218 days! This was twice the length of the longest survivor at 106 days, and calls into question their statement that non-survivors consumed only modest resources, even though median length of stay for non-survivors was 0.35 days. They also did not have any survivors until the last time period, after ECLS was incorporated into their treatment.

The authors do state that their study supports the use of K>12 mmol/L as a decision to stop resuscitation. While I don’t disagree, I would argue that it supports the use of a lower level, perhaps 10 or even 7 mmol/L. However, barring external trauma incompatible with life, packed snow in the airway, or physically being frozen, if they have a K lower than whatever cutoff you choose to use, you have to resuscitate them until they reach 34◦C. It is a retrospective study, and low patient numbers limit application of their data, but it’s unlikely that anyone can do a prospective trial on such a topic.

“Nobody is dead until warm and dead”: Prolonged resuscitation is warranted in arrested hypothermic victims also in remote areas – A retrospective study from northern Norway

Of note, volume 85 of the journal Resuscitation had quite a few articles about wilderness topics. This is the second one in two weeks, but people interested should look into the other articles.

Predicting survival after avalanches

More than 150 people die each year after being buried in an avalanche, and mortality is greater than 50% for this condition. Unfortunately, a large amount of resources are used on patients who ultimately expire, so determining which ones are likely to survive can safe costs and allow better utilization of resources such as extracorporeal life support (ECLS) warming and air evacuation.

Of the 3 common causes of cardiac arrest after avalanche, only hypothermia is likely to have good outcomes. Trauma and hypoxia have poor outcomes. Most algorithms have providers stop resuscitation for severe trauma, and airways packed with snow. However, ascertaining hypoxia vs hypothermia is less obvious. Prior attempts used potassium >10 mmol/L or >12 as a surrogate marker for cellular death from hypoxia, but no other markers are used.

So these authors took 20 years of data from the North French Alps, which ended up being only 48 patients with cardiac arrest.  18 of them had ROSC pre-hospital, and only of those 2 were eligible for ECLS. 19 of the 30 without ROSC were also eligible for ECLS. In total, only 8 survived, 5 from the pre-hospital ROSC group, and 3 from the non-ROSC. Of the 8 survivors, only 3 had favorable neurologic outcomes.

All of these were patients with rescue collapse, that is loss of vital signs after extrication or transfer. 3 other patients with rescue collapse died however. Other indicators for survival in their analysis are the presence of a rescue pocket, K <4.3 (nobody survived above 4.2, but some nonsurvivors had levels below this), and coagulation disturbances. Interestingly, their data showed no overlap of prothrombin time between survivors and non-survivors, but they sadly did not give the values, only as ratios. Other values such as PaO2, PaCO2, lactate, and bicarb are not predictive.

Unfortunately, for such a long time period of collections, there were very few survivors. The retrospective nature also limits analysis. It does look like we need to reduce the cutoff for resuscitation from values of K from 10-12 mmol/L to a lower number (7?). Also, identification of coagulation abnormalities may help. Perhaps POC thromboelastograms may be a way to identify those that do not merit resuscitation.

Survival after avalanche-induced cardiac arrest