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Medical Student
Uniformed Services University F. Edward Hebert School of Medicine
Ivan Yue, MS4
Medical Student
Uniformed Services University F. Edward Hebert School of Medicine
AAEM/RSA Publications and Social Media Committee
Alexander Li, MS4
Medical Student
Uniformed Services University F. Edward Hebert School of Medicine
Introduction
Avalanches are among the most feared events to occur in mountainous areas. Although the morbidity and mortality statistics are underreported worldwide, in North America and Europe combined there are roughly 140 avalanche-related deaths per year.[1,2] The majority of victims include snowboarders, skiers, mountaineers, and snowmobilers. With more people seeking to participate in snow sports or explore the mountains as part of expeditions, preparing to treat avalanche-related injuries is essential for an emergency physician working or traveling near a mountainous area. This article details the resuscitation guidelines that physicians can implement for those who fall victim to an avalanche as well as recommendations for mitigating avalanche exposure risk.
Method
The Wilderness Medical Society (WMS) developed robust guidelines for treating avalanche-related injuries based on three major components: prevention, rescue, and resuscitation.[3] This article specifically highlights resuscitation guidelines that emergency medicine physicians should know when faced with these injury patterns. While these guidelines are important for avalanche-related injuries, they can also be applicable to non-avalanche deep-snow and tree-well burial events as pathophysiology is similar.
Pathophysiology
Avalanche burial morbidity and mortality are variable based on several factors. These include the nature of traumatic injuries present, depth and duration of snow burial, airway patency, and the size of the victim’s air pocket. “Air pocket” refers to the volume of open space in front of the victim’s airway. This determines available oxygen the victim can access while buried. In non-avalanche snow burials, an individual is buried headfirst into the snow due to a tree well or deep snow. These patients are at highest risk of asphyxia. If the victim suffers a complete burial—meaning that the head and chest are completely below the snow— without other injury, they have a 48% chance of survival. However, in partial burials where some body part is out of the snow, studies have shown that the chance of survival is roughly 96% if the victim has not suffered any major traumatic injuries.[4]
The presence of a large air pocket is essential for survival of the victim because asphyxia is the most common cause of death in an avalanche burial. Evidence has shown that 75% of deaths are caused by asphyxia, 24% of deaths are due to major traumatic injuries, and a small number of deaths occur due to hypothermia.[5]
Resuscitation
The initial step in resuscitation is freeing the victim from the avalanche burial in order to start resuscitation as soon as possible. Cardiopulmonary resuscitation (CPR) and advanced life support (ALS) may be difficult as care often occurs in areas with limited resources, equipment, and personnel; however, resuscitation should start whenever the head and chest are exposed—even before the victim is completely freed from the snow. Maintaining a patent airway is also an important task and may be difficult in a wilderness environment.
Emergency physicians should be ready to continue resuscitation upon receiving an avalanche burial patient. The most recent update to the WMS guideline elaborates a cutoff for hypothermic resuscitation of patients who were buried for greater than sixty minutes with a core body temperature of <30 °C to reduce the number of futile attempts at resuscitation and conserve resources.
For patients who are uninjured and freed from a full burial, hypothermia is a great concern. Rewarming can be achieved passively or actively in accordance with local emergency department’s hypothermia guidelines.
Trauma is a major concern given the high-velocity nature of avalanches with extreme amounts of fast-moving debris. Patients with major trauma are more at risk of experiencing hypothermia and asphyxia; therefore, expeditious rescue from burial is vital. For those with possible cervical spine injuries, use the National Emergency X-Radiography Utilization Study (NEXUS) or Canadian C-Spine Rule to guide imaging and spinal immobilization.[3] Patients should also receive a full head-to-toe trauma examination. For an avalanche victim who is unconscious and cold to palpation, moderate to severe hypothermia should be on the differential and treated.
Initial evaluation of the patient includes immediate assessment of airway, breathing, and circulation. CPR and Advanced Cardiac Life Support (ACLS) should have begun en route to the emergency department. If the patient has been buried for less than sixty minutes and has a core body temperature greater than 30°C, extracorporeal life support (ECLS) rewarming is not indicated as cardiac arrest is most likely due to the trauma from the avalanche or asphyxia from burial. CPR should be performed for a maximum of thirty minutes in an attempt to achieve return of spontaneous circulation (ROSC); however, the chance of survival is minimal.[3]
If the patient is buried for greater than sixty minutes and has a core body temperature of less than 30°C with a patent airway at rescue, then ECLS is indicated. CPR should be continued for greater than 30 minutes if cardiac arrest is suspected to be secondary to hypothermia given the cutoffs listed previously. While defibrillation of a patient with a core body temperature less than 30°C may be unsuccessful, CPR should continue until the patient is rewarmed to above 30°C [3].
In cardiac arrest, defibrillation pads should be placed as soon as possible to analyze the rhythm. The WMS hypothermia guidelines state one defibrillation is indicated for patients in cardiac arrest with a shockable rhythm with a temperature <30°C, while the American Heart Association recommends defibrillation attempts every two minutes.[6] Finally, the European Resuscitation Council (ERC) recommends a maximum of three defibrillation attempts in patients with a temperature <30°C, and if the patient continues to be in a shockable rhythm, then delay additional attempts until they have been rewarmed to >30°C.[7]
Unconscious burial victims without a patent airway will benefit from endotracheal intubation and assisted ventilation, with a goal end-tidal carbon dioxide of 35-45 mmHg. Hyperventilation induces hypocapnia with resulting cerebrovascular vasoconstriction, causing further hypoperfusion of the brain, which is detrimental to those suffering from hypothermia or a traumatic brain injury.
Survival from avalanche-related traumatic cardiac arrest has never been reported. If the patient has a serum potassium of greater than 8 mmol/L upon hospital arrival, survival is unlikely, and Guidelines suggest rescuers can terminate resuscitation on this basis.[6]
Discussion
These guidelines and recommendations are provided by the Wilderness Medical Society and can be utilized by an emergency physician or aspiring medical student treating these patients. Above all, if encountering a patient who is buried in snow, emergency physicians must consider trauma and hypothermia. Another key takeaway from these guidelines is knowing when to initiate CPR, ACLS, and ECLS in addition to the criteria to terminate CPR in resource-limited rural emergency departments.
One major overlooked component of avalanche safety is decreasing the risk of being caught in an avalanche as much as possible. To do this, people should avoid dangerous areas, particularly during severe inclement weather. High-risk conditions include heavy snowfall, significant wind, and rapidly warming temperatures, as these factors are more likely to trigger an avalanche.[9] Proper route selection is also key for avoiding high-risk areas. Ways of decreasing the risk of triggering an avalanche include traveling in forested areas, walking along ridges, and avoiding slopes of greater than 30 degrees.[9] Additionally, there are avalanche beacons that transmit a signal to another beacon and ensuring that everyone in a traveling party has a beacon present would increase the chance of being found if one is buried in an avalanche. Practicing with one’s equipment beforehand is also an essential component of avalanche safety.
Further research into new breathing apparatuses, airbag systems, avalanche beacons, and recovery tools would be beneficial. Additionally, development of faster recovery methods would also benefit from future research.
References
[1]: Brugger H, Etter HJ, Zweifel B, et al. The impact of avalanche rescue devices on survival. Resuscitation. 2007;75(3):476-83.
[2]: Brugger H, Durrer B, Elsensohn F, et al. Resuscitation of avalanche victims: Evidence-based guidelines of the international commission for mountain emergency medicine (ICAR MEDCOM): intended for physicians and other advanced life support personnel. Resuscitation. 2013;84(5):539-46.
[3]: Van Tilburg C, Grissom CK, Zafren K, McIntosh S, Radwin MI, Paal P, Haegeli P, Smith WWR, Wheeler AR, Weber D, Tremper B, Brugger H. Wilderness Medical Society Practice Guidelines for Prevention and Management of Avalanche and Nonavalanche Snow Burial Accidents. Wilderness Environ Med. 2017 Mar;28(1):23-42. doi: 10.1016/j.wem.2016.10.004. PubMed PMID: 28257714.
[4]: Brugger H, Durrer B, Adler-kastner L, Falk M, Tschirky F. Field management of avalanche victims. Resuscitation. 2001;51(1):7-15.
[5]: Boyd J, Haegeli P, Abu-Laban RB, Shuster M, Butt JC. Patterns of death among avalanche fatalities: a 21-year review. CMAJ. 2009;180(5):507–512. doi:10.1503/cmaj.081327
[6]: Lavonas EJ, Drennan IR, Gabrielli A, et al. Part 10: Special Circumstances of Resuscitation: 2015 American Heart Association Guidelines Update for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care. Circulation. 2015;132(18 Suppl 2):S501-18.
[7]: Truhlář A, Deakin CD, Soar J, et al. European Resuscitation Council Guidelines for Resuscitation 2015: Section 4. Cardiac arrest in special circumstances. Resuscitation. 2015;95:148-201.
[8]: Cadman R. Eight nonavalanche snow-immersion deaths a 6-year series from british columbia ski areas. Phys Sportsmed. 1999;27(13):31-43.
[9]: Tremper, B. Staying Alive in Avalanche Terrain. 2nd ed. The Mountaineers, Seattle, WA; 2008.
Uniformed Services University F. Edward Hebert School of Medicine
Ivan Yue, MS4
Medical Student
Uniformed Services University F. Edward Hebert School of Medicine
AAEM/RSA Publications and Social Media Committee
Alexander Li, MS4
Medical Student
Uniformed Services University F. Edward Hebert School of Medicine
Introduction
Avalanches are among the most feared events to occur in mountainous areas. Although the morbidity and mortality statistics are underreported worldwide, in North America and Europe combined there are roughly 140 avalanche-related deaths per year.[1,2] The majority of victims include snowboarders, skiers, mountaineers, and snowmobilers. With more people seeking to participate in snow sports or explore the mountains as part of expeditions, preparing to treat avalanche-related injuries is essential for an emergency physician working or traveling near a mountainous area. This article details the resuscitation guidelines that physicians can implement for those who fall victim to an avalanche as well as recommendations for mitigating avalanche exposure risk.
Method
The Wilderness Medical Society (WMS) developed robust guidelines for treating avalanche-related injuries based on three major components: prevention, rescue, and resuscitation.[3] This article specifically highlights resuscitation guidelines that emergency medicine physicians should know when faced with these injury patterns. While these guidelines are important for avalanche-related injuries, they can also be applicable to non-avalanche deep-snow and tree-well burial events as pathophysiology is similar.
Pathophysiology
Avalanche burial morbidity and mortality are variable based on several factors. These include the nature of traumatic injuries present, depth and duration of snow burial, airway patency, and the size of the victim’s air pocket. “Air pocket” refers to the volume of open space in front of the victim’s airway. This determines available oxygen the victim can access while buried. In non-avalanche snow burials, an individual is buried headfirst into the snow due to a tree well or deep snow. These patients are at highest risk of asphyxia. If the victim suffers a complete burial—meaning that the head and chest are completely below the snow— without other injury, they have a 48% chance of survival. However, in partial burials where some body part is out of the snow, studies have shown that the chance of survival is roughly 96% if the victim has not suffered any major traumatic injuries.[4]
The presence of a large air pocket is essential for survival of the victim because asphyxia is the most common cause of death in an avalanche burial. Evidence has shown that 75% of deaths are caused by asphyxia, 24% of deaths are due to major traumatic injuries, and a small number of deaths occur due to hypothermia.[5]
Resuscitation
The initial step in resuscitation is freeing the victim from the avalanche burial in order to start resuscitation as soon as possible. Cardiopulmonary resuscitation (CPR) and advanced life support (ALS) may be difficult as care often occurs in areas with limited resources, equipment, and personnel; however, resuscitation should start whenever the head and chest are exposed—even before the victim is completely freed from the snow. Maintaining a patent airway is also an important task and may be difficult in a wilderness environment.
Emergency physicians should be ready to continue resuscitation upon receiving an avalanche burial patient. The most recent update to the WMS guideline elaborates a cutoff for hypothermic resuscitation of patients who were buried for greater than sixty minutes with a core body temperature of <30 °C to reduce the number of futile attempts at resuscitation and conserve resources.
For patients who are uninjured and freed from a full burial, hypothermia is a great concern. Rewarming can be achieved passively or actively in accordance with local emergency department’s hypothermia guidelines.
Trauma is a major concern given the high-velocity nature of avalanches with extreme amounts of fast-moving debris. Patients with major trauma are more at risk of experiencing hypothermia and asphyxia; therefore, expeditious rescue from burial is vital. For those with possible cervical spine injuries, use the National Emergency X-Radiography Utilization Study (NEXUS) or Canadian C-Spine Rule to guide imaging and spinal immobilization.[3] Patients should also receive a full head-to-toe trauma examination. For an avalanche victim who is unconscious and cold to palpation, moderate to severe hypothermia should be on the differential and treated.
Initial evaluation of the patient includes immediate assessment of airway, breathing, and circulation. CPR and Advanced Cardiac Life Support (ACLS) should have begun en route to the emergency department. If the patient has been buried for less than sixty minutes and has a core body temperature greater than 30°C, extracorporeal life support (ECLS) rewarming is not indicated as cardiac arrest is most likely due to the trauma from the avalanche or asphyxia from burial. CPR should be performed for a maximum of thirty minutes in an attempt to achieve return of spontaneous circulation (ROSC); however, the chance of survival is minimal.[3]
If the patient is buried for greater than sixty minutes and has a core body temperature of less than 30°C with a patent airway at rescue, then ECLS is indicated. CPR should be continued for greater than 30 minutes if cardiac arrest is suspected to be secondary to hypothermia given the cutoffs listed previously. While defibrillation of a patient with a core body temperature less than 30°C may be unsuccessful, CPR should continue until the patient is rewarmed to above 30°C [3].
In cardiac arrest, defibrillation pads should be placed as soon as possible to analyze the rhythm. The WMS hypothermia guidelines state one defibrillation is indicated for patients in cardiac arrest with a shockable rhythm with a temperature <30°C, while the American Heart Association recommends defibrillation attempts every two minutes.[6] Finally, the European Resuscitation Council (ERC) recommends a maximum of three defibrillation attempts in patients with a temperature <30°C, and if the patient continues to be in a shockable rhythm, then delay additional attempts until they have been rewarmed to >30°C.[7]
Unconscious burial victims without a patent airway will benefit from endotracheal intubation and assisted ventilation, with a goal end-tidal carbon dioxide of 35-45 mmHg. Hyperventilation induces hypocapnia with resulting cerebrovascular vasoconstriction, causing further hypoperfusion of the brain, which is detrimental to those suffering from hypothermia or a traumatic brain injury.
Survival from avalanche-related traumatic cardiac arrest has never been reported. If the patient has a serum potassium of greater than 8 mmol/L upon hospital arrival, survival is unlikely, and Guidelines suggest rescuers can terminate resuscitation on this basis.[6]
Discussion
These guidelines and recommendations are provided by the Wilderness Medical Society and can be utilized by an emergency physician or aspiring medical student treating these patients. Above all, if encountering a patient who is buried in snow, emergency physicians must consider trauma and hypothermia. Another key takeaway from these guidelines is knowing when to initiate CPR, ACLS, and ECLS in addition to the criteria to terminate CPR in resource-limited rural emergency departments.
One major overlooked component of avalanche safety is decreasing the risk of being caught in an avalanche as much as possible. To do this, people should avoid dangerous areas, particularly during severe inclement weather. High-risk conditions include heavy snowfall, significant wind, and rapidly warming temperatures, as these factors are more likely to trigger an avalanche.[9] Proper route selection is also key for avoiding high-risk areas. Ways of decreasing the risk of triggering an avalanche include traveling in forested areas, walking along ridges, and avoiding slopes of greater than 30 degrees.[9] Additionally, there are avalanche beacons that transmit a signal to another beacon and ensuring that everyone in a traveling party has a beacon present would increase the chance of being found if one is buried in an avalanche. Practicing with one’s equipment beforehand is also an essential component of avalanche safety.
Further research into new breathing apparatuses, airbag systems, avalanche beacons, and recovery tools would be beneficial. Additionally, development of faster recovery methods would also benefit from future research.
References
[1]: Brugger H, Etter HJ, Zweifel B, et al. The impact of avalanche rescue devices on survival. Resuscitation. 2007;75(3):476-83.
[2]: Brugger H, Durrer B, Elsensohn F, et al. Resuscitation of avalanche victims: Evidence-based guidelines of the international commission for mountain emergency medicine (ICAR MEDCOM): intended for physicians and other advanced life support personnel. Resuscitation. 2013;84(5):539-46.
[3]: Van Tilburg C, Grissom CK, Zafren K, McIntosh S, Radwin MI, Paal P, Haegeli P, Smith WWR, Wheeler AR, Weber D, Tremper B, Brugger H. Wilderness Medical Society Practice Guidelines for Prevention and Management of Avalanche and Nonavalanche Snow Burial Accidents. Wilderness Environ Med. 2017 Mar;28(1):23-42. doi: 10.1016/j.wem.2016.10.004. PubMed PMID: 28257714.
[4]: Brugger H, Durrer B, Adler-kastner L, Falk M, Tschirky F. Field management of avalanche victims. Resuscitation. 2001;51(1):7-15.
[5]: Boyd J, Haegeli P, Abu-Laban RB, Shuster M, Butt JC. Patterns of death among avalanche fatalities: a 21-year review. CMAJ. 2009;180(5):507–512. doi:10.1503/cmaj.081327
[6]: Lavonas EJ, Drennan IR, Gabrielli A, et al. Part 10: Special Circumstances of Resuscitation: 2015 American Heart Association Guidelines Update for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care. Circulation. 2015;132(18 Suppl 2):S501-18.
[7]: Truhlář A, Deakin CD, Soar J, et al. European Resuscitation Council Guidelines for Resuscitation 2015: Section 4. Cardiac arrest in special circumstances. Resuscitation. 2015;95:148-201.
[8]: Cadman R. Eight nonavalanche snow-immersion deaths a 6-year series from british columbia ski areas. Phys Sportsmed. 1999;27(13):31-43.
[9]: Tremper, B. Staying Alive in Avalanche Terrain. 2nd ed. The Mountaineers, Seattle, WA; 2008.
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