AvaLife-A New Multi-Disciplinary Approach Supported by Accident and Field Test Data to Optimize Survival Chances in Rescue and First Aid of Avalanche Patients

Abstract

Snow sports in the backcountry have seen a steep increase in popularity, and therefore preparedness for efficient companion and organized rescue is important. While technical rescue skills are widely taught, there is a lack of knowledge regarding first aid for avalanche patients. The stressful and time-critical situation for first responders requires a rule-based decision support tool. AvaLife has been designed from scratch, applying mathematical and statistical approaches including Monte Carlo simulations. New analysis of retrospective data and large prospective field test datasets were used to develop evidence-based algorithms exclusively for the avalanche rescue environment. AvaLife differs from other algorithms as it is not just a general-purpose CPR algorithm which has been slightly adapted for the avalanche patient. The sequence of actions, inclusion of the ≥150 cm burial depth triage criterion, advice to limit CPR duration for normothermic patients to 6 min in case of multiple burials and shortage of resources, criteria for using recovered subjects as a resource in the ongoing rescue, the adapted definition of "injuries incompatible with life", reasoning behind the utmost importance of rescue breaths, as well as the updated BLS-iCPR algorithm make AvaLife useful in single and multiple burial rescue. AvaLife is available as a companion rescue basic life support (BLS) version for the recreational user and an advanced companion and organized rescue BLS version for guides, ski patrols and mountain rescuers. AvaLife allows seamless interoperability with advanced life support (ALS) qualified medical personnel arriving on site.

Keywords: accidental; asphyxia; avalanche; basic life support; cardiac arrest; emergency medical services; hypothermia; mountain rescue.

Figure 1

Overview of AvaLife BLS modules. The different AvaLife modules follow step by step the chronology of the rescue and provide critical information for the technical as well as the medical part of avalanche rescue.

Figure 2

Mean burial depth of excavated subjects for different burial duration ranges. N = 1070.

Figure 3

Decrease in survival chances in % per meter of burial depth (N = 1012).

Figure 4

Survival chances based on burial duration and burial depth (N = 1070). The saturation of red for survived and blue for deceased cases increases with the increase in number of cases. For datapoints including survived and deceased cases, the gradually changing shading between red and blue is used to visualize the distribution of survived and deceased cases.

Figure 5

Required length of the snow conveyor belt (tan α) relative to slope inclination. The ramp angle of the snow conveyor belt must remain lower than 26° to prevent the snow to keep falling back towards the probe (empiric field test data [16]) and thus to ensure an efficient excavation effort. Illustration: www.MountainSafety.info as of 31 December 2021, reprinted with permission of www.MountainSafety.info.

Figure 6

Optimal number of rescuers for efficient excavation applying the snow conveyor belt technique [16]. Illustration: www.MountainSafety.info as of 31 December 2021, reprinted with permission of www.MountainSafety.info.

Figure 7

The search and excavate module of AvaLife including the burial depth threshold ≥150 cm and the criterion “2 or more rescuers per remaining buried subject”, which is important to distinguish cases where excavation shall start immediately from cases where the excavation shall be postponed in order to achieve “Greatest good for the greatest number”.

Figure 8

The Out-of-Hospital Medical Treatment module of AvaLife.

Figure 9

The iCPR module of AvaLife.

Figure 10

The Hypothermia Staging module of AvaLife.