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.

Boué Y et al. Survival after avalanche-induced cardiac arrest. Resuscitation. 2014 Sep;85(9):1192-6 [PMID 24971508]

Further Reading

• Hensley J. Do air pockets help avalanche survival? EBM Gone Wild
• Hensley J. Does that avalanche airbag really help? EBM Gone Wild
• Hensley J. Wear the helmet anyway. EBM Gone Wild
• Hensley J. Do ski helmets cause risk compensation?. EBM Gone Wild
• Hensley J. Treating serious frostbite. EBM Gone Wild