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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

      Abstract

      Background

      In North America and Europe ∼150 persons are killed by avalanches every year.

      Methods

      The International Commission for Mountain Emergency Medicine (ICAR MEDCOM) systematically developed evidence-based guidelines and an algorithm for the management of avalanche victims using a worksheet of 27 Population Intervention Comparator Outcome questions. Classification of recommendations and level of evidence are ranked using the American Heart Association system.

      Results and conclusions

      If lethal injuries are excluded and the body is not frozen, the rescue strategy is governed by the duration of snow burial and, if not available, by the victim's core-temperature. If burial time ≤35 min (or core-temperature ≥32 °C) rapid extrication and standard ALS is important. If burial time >35 min and core-temperature <32 °C, treatment of hypothermia including gentle extrication, full body insulation, ECG and core-temperature monitoring is recommended, and advanced airway management if appropriate. Unresponsive patients presenting with vital signs should be transported to a hospital capable of active external and minimally invasive rewarming such as forced air rewarming. Patients with cardiac instability or in cardiac arrest (with a patent airway) should be transported to a hospital for extracorporeal membrane oxygenation or cardiopulmonary bypass rewarming. Patients in cardiac arrest should receive uninterrupted CPR; with asystole, CPR may be terminated (or withheld) if a patient is lethally injured or completely frozen, the airway is blocked and duration of burial >35 min, serum potassium >12 mmol L−1, risk to the rescuers is unacceptably high or a valid do-not-resuscitate order exists. Management should include spinal precautions and other trauma care as indicated.

      Keywords

      1. Introduction

      In North America and Europe ∼150 persons are killed by avalanches every year,
      • Etter H.J.
      with most triggered by skiers, snowboarders and, in the USA and Canada, by snowmobilers.
      • Stethem C.
      • Jamieson B.
      • Schaerer P.
      • Liverman D.
      • German D.
      • Walker S.
      Snow avalanche hazard in Canada – a review.
      Avalanches inflict even higher death tolls in developing countries; for instance avalanches claimed 284 lives in South East Anatolia in 1992, >200 in Kashmir in 1995 and 135 in Kashmir in 2012. The total number of persons in avalanche terrain is unobtainable and mortality in these activity groups can only be roughly estimated. The first recommendations for on-site management and transport of avalanche victims, based on survival analyses,
      • Falk M.
      • Brugger H.
      • Adler-Kastner L.
      Avalanche survival chances.
      • Brugger H.
      • Durrer B.
      • Adler-Kastner L.
      • Falk M.
      • Tschirky F.
      Field management of avalanche victims.
      case reports
      • Althaus U.
      • Aeberhard P.
      • Schupbach P.
      • Nachbur B.H.
      • Muhlemann W.
      Management of profound accidental hypothermia with cardiorespiratory arrest.
      and case series,
      • Schaller M.D.
      • Fischer A.P.
      • Perret C.H.
      • Hyperkalemia
      A prognostic factor during acute severe hypothermia.
      • Locher T.
      • Walpoth B.
      • Pfluger D.
      • Althaus U.
      Accidental hypothermia in Switzerland (1980–1987)—case reports and prognostic factors.
      • Mair P.
      • Kornberger E.
      • Furtwaengler W.
      • Balogh D.
      • Antretter H.
      Prognostic markers in patients with severe accidental hypothermia and cardiocirculatory arrest.
      • Walpoth B.H.
      • Walpoth-Aslan B.N.
      • Mattle H.P.
      • et al.
      Outcome of survivors of accidental deep hypothermia and circulatory arrest treated with extracorporeal blood warming.
      were proposed in 1996
      • Brugger H.
      • Durrer B.
      • Adler-Kastner L.
      On-site triage of avalanche victims with asystole by the emergency doctor.
      and 2001.
      • Brugger H.
      • Durrer B.
      • Adler-Kastner L.
      • Falk M.
      • Tschirky F.
      Field management of avalanche victims.
      The International Commission for Mountain Emergency Medicine (ICAR MEDCOM) established official consensus guidelines including an algorithm in 2002.
      • Brugger H.
      • Durrer B.
      On-site treatment of avalanche victims ICAR-MEDCOM-recommendation.
      A systematic review of four prognostic factors
      • Boyd J.
      • Brugger H.
      • Shuster M.
      Prognostic factors in avalanche resuscitation: a systematic review.
      and an International Liaison Committee on Resuscitation (ILCOR) worksheet process were the basis of the recommendations for avalanche resuscitation in the 2010 Resuscitation Guidelines.
      • Soar J.
      • Perkins G.D.
      • Abbas G.
      • et al.
      European Resuscitation Council Guidelines for Resuscitation 2010 Section 8. Cardiac arrest in special circumstances: Electrolyte abnormalities, poisoning, drowning, accidental hypothermia, hyperthermia, asthma, anaphylaxis, cardiac surgery, trauma, pregnancy, electrocution.
      • Vanden Hoek T.L.
      • Morrison L.J.
      • Shuster M.
      • et al.
      Part 12: cardiac arrest in special situations: 2010 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care.
      Recommendations for transport and treatment decisions of hypothermic patients including avalanche victims have been recently developed.
      • Brown D.
      • Brugger H.
      • Boyd J.
      • Paal P.
      Accidental hypothermia.
      The ICAR MEDCOM sought to systematically develop evidence-based guidelines using a structured worksheet with the mandate to obtain final consensus among the ICAR MEDCOM.

      2. Methods

      The objectives, inclusion/exclusion criteria, working group and worksheet of 27 Population Intervention Comparator Outcome (PICO) questions (supplementary data) derived from earlier avalanche resuscitation recommendations
      • Brugger H.
      • Durrer B.
      • Adler-Kastner L.
      • Falk M.
      • Tschirky F.
      Field management of avalanche victims.
      were developed by the ICAR MEDCOM at a TOPIC meeting. The electronic database of Medline was searched via PubMed with the search terms (avalanche [All Fields]) and (hypothermia [All Fields]) and the database of EMBASE via OVID with (avalanche {Including Related Terms}) and (hypothermia {Including Related Terms}). The Cochrane Database of Systematic Reviews was searched with the terms (avalanche) and (accidental hypothermia). Additional hand searching of articles, reference texts and reference lists was also performed. All articles relevant to clinical management of victims of snow avalanches and related accidental hypothermia were extracted for further review. These were evaluated for quality and relevance to the PICO questions and recommendations were developed at a SCIENCE meeting. The recommendations were further examined and consensus was reached at a MANUSCRIPT meeting in Åre, Sweden, in October 2011. Classification of recommendations and level of evidence are ranked using the American Heart Association (AHA) system (Table 1).
      Table 1Classification of recommendations and level of evidence according to the ACCF/AHA task force on practice guidelines.
      Manual for ACC/AHA Guideline Writing Committees (Accessed 01 September 2012, at http://circ.ahajournals.org/site/manual/index.xhtml).
      Size of treatment effect
      LEVEL (Quality) of evidence (LOE)
      CLASS ICLASS IIaCLASS IIbCLASS III
      Benefit>>>RiskBenefit>>RiskBenefitRiskNo Benefit or Harm
      Procedure/Treatment should be performed/administeredIt is reasonable to perform procedure/administer treatmentProcedure/Treatment may be consideredProcedure/Treatment of no benefit or harmful
      LEVEL ARecommendation that procedure or treatment is useful/effective.Recommendation in favor of treatment or procedure being useful/effective.Recommendation's usefulness/efficacy less well established.Recommendation that procedure or treatment is not useful/effective and may be harmful.
      Data derived from multiple randomized clinical trials or meta-analysesSufficient evidence from multiple randomized trials or meta-analyses.Some conflicting evidence from multiple randomized trials or meta-analyses.Greater conflicting evidence from multiple randomized trials or meta-analyses.Sufficient evidence from multiple randomized trials or meta-analyses.
      LEVEL BRecommendation that procedure or treatment is useful/effective.Recommendation in favor of treatment or procedure being useful/effective.Recommendation's usefulness/efficacy less well established.Recommendation that procedure or treatment is not useful/effective and may be harmful.
      Data derived from a single randomized trial or nonrandomized studiesEvidence from single randomized trial or nonrandomized studies.Some conflicting evidence from single randomized trial or nonrandomized studies.Greater conflicting evidence from single randomized trial or nonrandomized studies.Evidence from single randomized trial or nonrandomized studies.
      LEVEL CRecommendation that procedure or treatment is useful/effective.Recommendation in favor of treatment or procedure being useful/effective.Recommendation's usefulness/efficacy less well established.Recommendation that procedure or treatment is not useful/effective and may be harmful.
      Only consensus opinion of experts, case studies, or standard of careOnly expert opinion, case, or standard of care.Only diverging expert opinion, case studies, or standard of care.Only diverging expert opinion, case studies, or standard of care.Only diverging expert opinion, case studies, or standard of care.
      a Manual for ACC/AHA Guideline Writing Committees (Accessed 01 September 2012, at http://circ.ahajournals.org/site/manual/index.xhtml).

      3. Findings and recommendations

      From a total of 3530 retrieved citations, 96 articles were classified as relevant and were subjected to full review.

      Survival probability

      The overall survival rate of avalanche victims is 77% (1453/1886).
      • Brugger H.
      • Durrer B.
      • Adler-Kastner L.
      • Falk M.
      • Tschirky F.
      Field management of avalanche victims.
      Survival depends on the grade and duration of burial and the pathological processes of asphyxia, trauma and hypothermia.

      Grade of burial

      Analysis of a Swiss sample showed that 39% (735/1886) of victims involved in an avalanche were completely buried, with survival in complete burials (i.e. burial of the head and chest
      In Europe the term completely buried refers to burial of at least the head and chest. In North America the term completely buried is reserved for when the individual is totally buried beneath the snow surface and partially buried–critical for when the individual is partially buried with at least the head under the snow surface and with breathing impaired.
      • Canadian Avalanche Association
      Observation guidelines and recording standards for weather, snowpack and avalanches.
      • Greene E.
      • Atkins D.
      • Birkeland K.
      • et al.
      Snow, weather, and avalanches: observational guidelines for Avalanche Programs in the United States.
      The term critical burial will be used hereafter to identify burials that impair breathing and therefore risk asphyxia.
      ) of 47.6% (350/735) versus 95.8% (1103/1151) in partial burials.
      • Brugger H.
      • Durrer B.
      • Adler-Kastner L.
      • Falk M.
      • Tschirky F.
      Field management of avalanche victims.
      Grade of burial is the strongest single factor for survival.

      Duration of burial

      Biostatistical survival analysis of critically buried victims1 in Switzerland and Canada shows a progressive non-linear reduction in survival as duration of burial increases and distinct phases.
      • Falk M.
      • Brugger H.
      • Adler-Kastner L.
      Avalanche survival chances.
      • Brugger H.
      • Durrer B.
      • Adler-Kastner L.
      • Falk M.
      • Tschirky F.
      Field management of avalanche victims.
      • Boyd J.
      • Haegeli P.
      • Abu-Laban R.B.
      • Shuster M.
      • Butt J.C.
      Patterns of death among avalanche fatalities: a 21-year review.
      In Switzerland, survival probability remains above 80% until 18 min after burial (“survival phase”) and plummets thereafter to 32% (“asphyxia phase”), whereas the Canadian survival curve shows an earlier and steeper decline from 77% at 10 min to 7% at 35 min, which reflects a greater mortality from trauma and an earlier onset of asphyxia due to denser snow in some regions of Canada
      • Boyd J.
      • Haegeli P.
      • Abu-Laban R.B.
      • Shuster M.
      • Butt J.C.
      Patterns of death among avalanche fatalities: a 21-year review.
      • Haegeli P.
      • Falk M.
      • Brugger H.
      • Etter H.J.
      • Boyd J.
      Comparison of avalanche survival patterns in Canada and Switzerland.
      (Fig. 1). Supportively, hypoxia has been shown to be correlated to snow density in an experimental study.
      • Brugger H.
      • Sumann G.
      • Meister R.
      • et al.
      Hypoxia and hypercapnia during respiration into an artificial air pocket in snow: implications for avalanche survival.
      Another identifiable decrease in survival occurs at 90 min due to hypothermia combined with hypoxia and hypercapnia.
      • Brugger H.
      • Durrer B.
      • Adler-Kastner L.
      • Falk M.
      • Tschirky F.
      Field management of avalanche victims.
      The duration of burial is therefore an indication of pathology and should dictate treatment strategy.
      Figure thumbnail gr1
      Fig. 1Comparison of survival curves in Canada (black; n = 301) and Switzerland (grey; n = 946) from 1980 to 2005.
      Extracted from Haegeli et al.
      • Boyd J.
      • Haegeli P.
      • Abu-Laban R.B.
      • Shuster M.
      • Butt J.C.
      Patterns of death among avalanche fatalities: a 21-year review.
      with permission from CMAJ.

      3.1 Asphyxia

      Asphyxia was found to be the most common cause of death in three case series that relied on autopsy, full forensic external examination and/or pre-mortem clinical findings.
      • Boyd J.
      • Haegeli P.
      • Abu-Laban R.B.
      • Shuster M.
      • Butt J.C.
      Patterns of death among avalanche fatalities: a 21-year review.
      • Hohlrieder M.
      • Brugger H.
      • Schubert H.M.
      • Pavlic M.
      • Ellerton J.
      • Mair P.
      Pattern and severity of injury in avalanche victims.
      • McIntosh S.E.
      • Grissom C.K.
      • Olivares C.R.
      • Kim H.S.
      • Tremper B.
      Cause of death in avalanche fatalities.
      Asphyxia may occur in combination with trauma and hypothermia.
      • Boyd J.
      • Haegeli P.
      • Abu-Laban R.B.
      • Shuster M.
      • Butt J.C.
      Patterns of death among avalanche fatalities: a 21-year review.

      3.1.1 Expediency

      Survival decreases rapidly in the “asphyxia phase”, i.e. in the first 35 min.
      • Falk M.
      • Brugger H.
      • Adler-Kastner L.
      Avalanche survival chances.
      • Brugger H.
      • Durrer B.
      • Adler-Kastner L.
      • Falk M.
      • Tschirky F.
      Field management of avalanche victims.
      • Haegeli P.
      • Falk M.
      • Brugger H.
      • Etter H.J.
      • Boyd J.
      Comparison of avalanche survival patterns in Canada and Switzerland.
      Recommendations. Companions should locate and extricate buried victims expeditiously (Class 1, LOE B).
      Organized rescue should be mobilized early (Class I, LOE B).

      3.1.2 Duration of burial and airway patency

      A systematic review
      • Boyd J.
      • Brugger H.
      • Shuster M.
      Prognostic factors in avalanche resuscitation: a systematic review.
      confirmed that a patent airway was essential for survival for >35 min of critical burial, with four of the analyzed retrospective studies describing survival to hospital discharge in victims buried >60 min who were found with patent airways. No survivors were reported in any of the 14 case-control and case series for victims with an obstructed airway and >35 min of burial. A prospective, randomized, crossover experimental study found that when breathing into a simulated air pocket subjects achieved a steady state of survivable hypoxia for at least 20 min in 39% (11/28) of uninterrupted tests.
      • Brugger H.
      • Sumann G.
      • Meister R.
      • et al.
      Hypoxia and hypercapnia during respiration into an artificial air pocket in snow: implications for avalanche survival.
      Other prospective experimental studies have indicated that redirecting gas exchange away from an air pocket, such as might occur in avalanche debris with large blocks or an opening to environmental air, improves oxygenation.
      • Grissom C.K.
      • Radwin M.I.
      • Harmston C.H.
      • Hirshberg E.L.
      • Crowley T.J.
      Respiration during snow burial using an artificial air pocket.
      • Radwin M.I.
      • Grissom C.K.
      • Scholand M.B.
      • Harmston C.H.
      Normal oxygenation and ventilation during snow burial by the exclusion of exhaled carbon dioxide.
      • Paal P.
      • Strapazzon G.
      • Braun P.
      • et al.
      Factors affecting survival from avalanche burial—a randomized prospective porcine pilot study.
      Recommendation. If burial >35 min, airway patency should be determined upon exposure of the face (Class I, LOE A).
      The ancillary presence of an air pocket should be determined by digging from the side of the victim in order to not harm the victim or destroy the air pocket (Class I, LOE C).

      3.1.3 Resuscitation

      Resuscitation guidelines recommend standard CPR in hypoxaemic cardiopulmonary arrest.
      • Soar J.
      • Perkins G.D.
      • Abbas G.
      • et al.
      European Resuscitation Council Guidelines for Resuscitation 2010 Section 8. Cardiac arrest in special circumstances: Electrolyte abnormalities, poisoning, drowning, accidental hypothermia, hyperthermia, asthma, anaphylaxis, cardiac surgery, trauma, pregnancy, electrocution.
      • Vanden Hoek T.L.
      • Morrison L.J.
      • Shuster M.
      • et al.
      Part 12: cardiac arrest in special situations: 2010 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care.
      Ventilation should be combined with chest compressions, as compression-only CPR is inappropriate for avalanche burial.
      Recommendations. Factors and decisions are integrated in a management algorithm (Fig. 2) (Class IIa, LOE C).
      Figure thumbnail gr2
      Fig. 2Management of the buried avalanche victim. In all cases gentle extrication and spinal precautions. Where appropriate core temperature and ECG monitoring, oxygen, insulation, heat packs on trunk; 0.9% NaCl and/or 5% glucose only if an intravenous or intraosseous line can be established within a few minutes; specific trauma care as indicated. 0Clinicians may consider withholding resuscitation at the scene if it increases risk to the rescue team or if the victim is lethally injured or completely frozen. 1If duration of burial is unknown core temperature may substitute. 2Initiate standard ALS including ventilations and chest compressions as indicated. Resuscitation may be terminated in normothermic patients if ALS is not successful after 20 min. Transport victims with concern of respiratory (e.g. pulmonary oedema) or other-system injury to the most appropriate medical centre. 3Hospital capable of advanced external or core rewarming. Patients who present with cardiac instability (ventricular arrhythmias, systolic blood pressure <90 mm Hg) or core-temperature <28 °C should be transported towards ECC rewarming. Defibrillation beyond three attempts may be delayed until core-temperature >30 °C. *If direct transport to ECC rewarming is practical, the nearest ED can be bypassed. If K+ at hospital admission exceeds 12 mmol L−1, consider stopping resuscitation (after excluding crush injuries and consideration of the use of depolarizing paralytics); in an adult with K+ 8–12 mmol L−1 and other factors consistent with non-survival, termination of resuscitation should be considered. ALS, Advanced Life Support; ED, Emergency Department; ICU, Intensive Care Unit; ECC, extracorporeal circulation.
      For victims buried <35 min found in cardiac arrest, presume asphyxia and initiate standard CPR with ventilations as soon as the head and chest are free regardless of airway patency (Class I, LOE B).
      For victims buried >35 min found in non-asystolic cardiac arrest with a patent airway but who are not hypothermic (≥32 °C), presume asphyxia and initiate standard CPR with ventilations as soon as the head and chest are free (Class IIa, LOE B).
      For victims buried >35 min found in asystolic cardiac arrest with an obstructed airway, resuscitation may be initiated but can be terminated if not successful (Class I, LOE A).

      3.1.4 Advanced airway

      Advanced airway management (e.g. endotracheal intubation and supraglottic airway devices) performed by experienced personnel enables effective ventilation, reduces the likelihood of aspiration for avalanche victims in periarrest
      • Vanden Hoek T.L.
      • Morrison L.J.
      • Shuster M.
      • et al.
      Part 12: cardiac arrest in special situations: 2010 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care.
      and may improve survival.
      • Bernhard M.
      • Bottiger B.W.
      Out-of-hospital endotracheal intubation of trauma patients: straight back and forward to the gold standard!.
      In prehospital settings with long transport times, endotracheal intubation is associated with improved survival.
      • Neumar R.W.
      • Otto C.W.
      • Link M.S.
      • et al.
      Part 8: adult advanced cardiovascular life support: 2010 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care.
      However, complications are unacceptably frequent when performed by inexperienced providers.
      • Neumar R.W.
      • Otto C.W.
      • Link M.S.
      • et al.
      Part 8: adult advanced cardiovascular life support: 2010 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care.
      • Deakin C.D.
      • Nolan J.P.
      • Soar J.
      • et al.
      European Resuscitation Council Guidelines for Resuscitation 2010 Section 4. Adult advanced life support.
      Supraglottic devices may be more efficient and safer than endotracheal intubation or bag-mask ventilation for less experienced rescuers.
      Recommendations. For unresponsive victims advanced airway management should be performed if the rescuer is competent in this skill and if airway management succeeds within a reasonable time (Class I, LOE A).
      For rescuers not experienced in advanced airway management, ventilation is most effective with mouth-to-mask or bag-mask techniques (Class I, LOE A).
      For a potential survivor with a failed airway, hospital transfer should be hastened with early alert of appropriate support (Class I, LOE C).

      3.1.5 Transport

      Post-resuscitation care including therapeutic hypothermia is integral to improving survival.
      • Neumar R.W.
      • Otto C.W.
      • Link M.S.
      • et al.
      Part 8: adult advanced cardiovascular life support: 2010 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care.
      • Deakin C.D.
      • Nolan J.P.
      • Soar J.
      • et al.
      European Resuscitation Council Guidelines for Resuscitation 2010 Section 4. Adult advanced life support.
      Mechanical chest compression devices improve rescuer safety and reduce manual energy expenditure and may improve outcome during transport.
      • Deakin C.D.
      • Nolan J.P.
      • Soar J.
      • et al.
      European Resuscitation Council Guidelines for Resuscitation 2010 Section 4. Adult advanced life support.
      Delayed onset of pulmonary oedema has been reported in avalanche victims with vital signs after short burials.
      • Schmid F.
      [The pathogenesis of pulmonary edema after being buried by an avalanche].
      Recommendations. If resuscitation is successful or termination-of-CPR criteria are not met (see Termination of CPR) victims should be transported to the nearest hospital, preferably one with intensive care services (Class IIa, LOE C).
      Mechanical chest compression devices and therapeutic hypothermia may be considered for prolonged transports (Class IIb, LOE B).
      If victims present with signs or concern of respiratory or other system injury they should be transported to the nearest emergency department for advanced assessment and observation (Class I, LOE C).

      3.2 Trauma

      Trauma was the principal cause of death in 23.5% (48/204) of fatalities in western Canada,
      • Boyd J.
      • Haegeli P.
      • Abu-Laban R.B.
      • Shuster M.
      • Butt J.C.
      Patterns of death among avalanche fatalities: a 21-year review.
      5.5% (2/36) in Austria
      • Hohlrieder M.
      • Brugger H.
      • Schubert H.M.
      • Pavlic M.
      • Ellerton J.
      • Mair P.
      Pattern and severity of injury in avalanche victims.
      and 5.4% (3/56) in Utah.
      • McIntosh S.E.
      • Grissom C.K.
      • Olivares C.R.
      • Kim H.S.
      • Tremper B.
      Cause of death in avalanche fatalities.
      However, in the Canadian sample major trauma, i.e. injury severity score (ISS) >15, was additionally found in 13.0% (12/92) of autopsied “asphyxia” fatalities. Chest trauma represented 45.8% (11/24) of single-system injuries; 52.1% (25/48) were found on the surface or not critically buried.
      • Boyd J.
      • Haegeli P.
      • Abu-Laban R.B.
      • Shuster M.
      • Butt J.C.
      Patterns of death among avalanche fatalities: a 21-year review.
      In the Austrian sample 8.6% (9/105) of fatality cases had an ISS score >13 although only 5.5% (2/36) were ascribed to trauma; the two trauma fatalities were fracture-dislocations of the cervical spine.
      • Hohlrieder M.
      • Brugger H.
      • Schubert H.M.
      • Pavlic M.
      • Ellerton J.
      • Mair P.
      Pattern and severity of injury in avalanche victims.
      Similarly, in the Utah sample trauma was associated with asphyxia in 8.9% (5/56) of fatalities in addition to the 5.4% (3/56) ascribed to trauma alone; autopsies found head, abdominal and limb injuries to be common.
      • McIntosh S.E.
      • Grissom C.K.
      • Olivares C.R.
      • Kim H.S.
      • Tremper B.
      Cause of death in avalanche fatalities.
      Differing rates are dependent on topographical factors (e.g. open versus forested terrain).
      • Boyd J.
      • Haegeli P.
      • Abu-Laban R.B.
      • Shuster M.
      • Butt J.C.
      Patterns of death among avalanche fatalities: a 21-year review.

      3.2.1 On-site management

      Current resuscitation guidelines emphasize spinal stabilization, chest decompression for tension pneumothorax, haemorrhage control, prompt evacuation to definitive care and consideration of permissive hypotension in the resuscitation of shock.
      • Soar J.
      • Perkins G.D.
      • Abbas G.
      • et al.
      European Resuscitation Council Guidelines for Resuscitation 2010 Section 8. Cardiac arrest in special circumstances: Electrolyte abnormalities, poisoning, drowning, accidental hypothermia, hyperthermia, asthma, anaphylaxis, cardiac surgery, trauma, pregnancy, electrocution.
      • Vanden Hoek T.L.
      • Morrison L.J.
      • Shuster M.
      • et al.
      Part 12: cardiac arrest in special situations: 2010 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care.
      Tourniquets are life-saving in exsanguinating limb injuries.
      • Kragh Jr., J.F.
      • Walters T.J.
      • Baer D.G.
      • et al.
      Survival with emergency tourniquet use to stop bleeding in major limb trauma.
      In traumatic cardiac arrest survival is approximately 5.6% and prolonged CPR >16 min is associated with a poor outcome.
      • Soar J.
      • Perkins G.D.
      • Abbas G.
      • et al.
      European Resuscitation Council Guidelines for Resuscitation 2010 Section 8. Cardiac arrest in special circumstances: Electrolyte abnormalities, poisoning, drowning, accidental hypothermia, hyperthermia, asthma, anaphylaxis, cardiac surgery, trauma, pregnancy, electrocution.
      In severe head trauma outcomes are improved with early intubation and normoventilation while hypo- and hyperventilation result in poorer outcome.
      • Davis D.P.
      • Peay J.
      • Sise M.J.
      • et al.
      Prehospital airway and ventilation management: a trauma score and injury severity score-based analysis.
      Recommendations. Rescuers should provide adequate spinal stabilization throughout extrication, on-scene management and transport (Class I, LOE C).
      Trauma measures include splinting, insulation and analgesia (Class I, LOE C).
      Clinical teams should be skilled and equipped for thoracostomy, tourniquet application, intravenous or intraosseous cannulation with controlled fluid infusion in shock or for medication administration, advanced airway management, cricothyrotomy and antibiotics for open fractures (Class IIa, LOE B).
      CPR should be initiated for traumatic cardiopulmonary arrest while searching for and managing treatable causes (Class I, LOE B).
      Delay of transport for on-site management should be as short as possible; direct transport to a dedicated trauma centre is preferred (Class I, LOE C).

      3.3 Hypothermia

      Hypothermia is commonly diagnosed clinically in avalanche victims. A systematic review of five retrospective case series found that hypothermic cardiac arrest is survivable if associated with a patent airway.
      • Boyd J.
      • Brugger H.
      • Shuster M.
      Prognostic factors in avalanche resuscitation: a systematic review.
      Hypothermia is rarely listed as the principal cause of death as post-mortem signs are limited and asphyxia and trauma are frequently concomitant.
      • Boyd J.
      • Haegeli P.
      • Abu-Laban R.B.
      • Shuster M.
      • Butt J.C.
      Patterns of death among avalanche fatalities: a 21-year review.
      At low core-temperatures the brain tolerates cardio-circulatory arrest >5 min without permanent damage.
      • Walpoth B.H.
      • Walpoth-Aslan B.N.
      • Mattle H.P.
      • et al.
      Outcome of survivors of accidental deep hypothermia and circulatory arrest treated with extracorporeal blood warming.
      • Gilbert M.
      • Busund R.
      • Skagseth A.
      • Nilsen P.A.
      • Solbo J.P.
      Resuscitation from accidental hypothermia of 13.7 °C with circulatory arrest.
      • Oberhammer R.
      • Beikircher W.
      • Hormann C.
      • et al.
      Full recovery of an avalanche victim with profound hypothermia and prolonged cardiac arrest treated by extracorporeal re-warming.

      3.3.1 Cooling rate

      The cooling rate during burial is variable but may be accelerated by light clothing, sweating and exhaustion. Hypercapnia and hypoxia may increase cooling rate.
      • Paal P.
      • Strapazzon G.
      • Braun P.
      • et al.
      Factors affecting survival from avalanche burial—a randomized prospective porcine pilot study.
      • Grissom C.K.
      • Radwin M.I.
      • Scholand M.B.
      • Harmston C.H.
      • Muetterties M.C.
      • Bywater T.J.
      Hypercapnia increases core temperature cooling rate during snow burial.
      This combination has been termed the “triple H syndrome,”
      • Brugger H.
      • Sumann G.
      • Meister R.
      • et al.
      Hypoxia and hypercapnia during respiration into an artificial air pocket in snow: implications for avalanche survival.
      although the interactions are not elucidated. A maximum cooling rate of 9 °C h−1 was found during a burial of 100 min,
      • Oberhammer R.
      • Beikircher W.
      • Hormann C.
      • et al.
      Full recovery of an avalanche victim with profound hypothermia and prolonged cardiac arrest treated by extracorporeal re-warming.
      while lesser cooling rates have been reported in other case series and reports
      • Locher T.
      • Walpoth B.
      Differential diagnosis of circulatory failure in hypothermic avalanche victims: retrospective analysis of 32 avalanche accidents.
      • Putzer G.
      • Schmid S.
      • Braun P.
      • Brugger H.
      • Paal P.
      Cooling of six centigrades in an hour during avalanche burial.
      • Strapazzon G.
      • Beikircher W.
      • Procter E.
      • Brugger H.
      Electrical heart activity recorded during prolonged avalanche burial.
      and in experimental human
      • Grissom C.K.
      • Harmston C.H.
      • McAlpine J.C.
      • et al.
      Spontaneous endogenous core temperature rewarming after cooling due to snow burial.
      and animal studies.
      • Paal P.
      • Strapazzon G.
      • Braun P.
      • et al.
      Factors affecting survival from avalanche burial—a randomized prospective porcine pilot study.
      At the maximum rate of 9 °C h−1 a minimum time of 35 min is required for the core-temperature to drop <32 °C and it is therefore concluded that the presence of a patent airway is essential for survival in any victim with a core-temperature <32 °C.
      • Boyd J.
      • Brugger H.
      • Shuster M.
      Prognostic factors in avalanche resuscitation: a systematic review.
      • Soar J.
      • Perkins G.D.
      • Abbas G.
      • et al.
      European Resuscitation Council Guidelines for Resuscitation 2010 Section 8. Cardiac arrest in special circumstances: Electrolyte abnormalities, poisoning, drowning, accidental hypothermia, hyperthermia, asthma, anaphylaxis, cardiac surgery, trauma, pregnancy, electrocution.
      • Vanden Hoek T.L.
      • Morrison L.J.
      • Shuster M.
      • et al.
      Part 12: cardiac arrest in special situations: 2010 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care.
      Recommendations. (See Table 2 for the management of victims at different stages of hypothermia and Fig. 2 for the management of avalanche victims.)
      Table 2Staging and management of hypothermic avalanche victims.
      CTSwiss staging
      Durrer et al.39 This Swiss staging system was adopted by the 2010 ERC Guidelines for Resuscitation. The clinical signs in the Swiss staging system reflect the effect of hypothermia only. Considering that consciousness can be impaired by asphyxia and trauma, core temperature measurement is necessary to assess the severity of hypothermia.13
      Danzl
      Danzl.38
      TreatmentTransfer
      35–32 °CHypothermia I:

      conscious, shivering
      Mild hypothermia• Move activelyNearest ED
      • Drink warm, sweetened fluids
      If transport delayed >2h and no signs of trauma that would necessitate anaesthesia.
      • Insulation
      32–28 °CHypothermia II:

      impaired consciousness, without shivering
      Moderate hypothermia• Gently extricate and immobilize horizontallyStable circulation: hospital with active rewarming facilities
      • Continuously monitor with ECG and core temperatureUnstable circulation: hospital with ECMO/CPB
      • Full body insulation
      • Apply chemical heat packs to trunk
      • Administer oxygen
      • Place iv or io line, without considerably delaying transport
      28–24 °CHypothermia III:

      unconscious
      Severe hypothermiaAdditionally -Stable circulation: hospital with active rewarming facilities
      • Protect upper airway: Recovery position or if reasonable advanced airway managementUnstable circulation: hospital with ECMO/CPB
      • Try to avoid depolarizing paralytic agents
      • Withhold or carefully dose drugs (slow metabolism!)
      <24 °C
      13.7°C is the lowest core temperature recorded in a survivor of accidental hypothermia. ALS, advanced life support; CT, core temperature; ECMO/CPB, extracorporeal rewarming/cardiopulmonary bypass; ED, emergency department.
      Hypothermia IV:

      no vital signs
      Severe and profound (<20 °C) hypothermiaAdditionally -Hospital with ECMO/CPB
      • Standard CPR
      • Avoid excessive defibrillation attempts
      a Durrer et al.
      • Durrer B.
      • Brugger H.
      • Syme D.
      International Commission for Mountain Emergency Medicine. The medical on-site treatment of hypothermia: ICAR-MEDCOM recommendation.
      This Swiss staging system was adopted by the 2010 ERC Guidelines for Resuscitation. The clinical signs in the Swiss staging system reflect the effect of hypothermia only. Considering that consciousness can be impaired by asphyxia and trauma, core temperature measurement is necessary to assess the severity of hypothermia.
      • Soar J.
      • Perkins G.D.
      • Abbas G.
      • et al.
      European Resuscitation Council Guidelines for Resuscitation 2010 Section 8. Cardiac arrest in special circumstances: Electrolyte abnormalities, poisoning, drowning, accidental hypothermia, hyperthermia, asthma, anaphylaxis, cardiac surgery, trauma, pregnancy, electrocution.
      b Danzl.
      • Danzl D.F.
      Accidental hypothermia.
      c If transport delayed >2 h and no signs of trauma that would necessitate anaesthesia.
      d 13.7 °C is the lowest core temperature recorded in a survivor of accidental hypothermia.ALS, advanced life support; CT, core temperature; ECMO/CPB, extracorporeal rewarming/cardiopulmonary bypass; ED, emergency department.
      For victims in cardiac arrest with a core-temperature <32 °C and a patent or unknown airway initiate resuscitation (Class I, LOE A).
      For victims in asystolic cardiac arrest with a core-temperature <32 °C and an obstructed airway, presume asphyxia and withhold resuscitation (Class I, LOE A).

      3.3.2 Rescue collapse

      Collapse of hypothermic avalanche victims during rescue is associated with lethal arrhythmias, according to case reports.
      • Oberhammer R.
      • Beikircher W.
      • Hormann C.
      • et al.
      Full recovery of an avalanche victim with profound hypothermia and prolonged cardiac arrest treated by extracorporeal re-warming.
      • Strapazzon G.
      • Beikircher W.
      • Procter E.
      • Brugger H.
      Electrical heart activity recorded during prolonged avalanche burial.
      Mechanical stimulation has been shown to produce lethal arrhythmias in a porcine model of hypothermia.
      • Grueskin J.
      • Tanen D.A.
      • Harvey P.
      • Santos F.D.
      • Richardson III, W.H.
      • Riffenburgh R.H.
      A pilot study of mechanical stimulation and cardiac dysrhythmias in a porcine model of induced hypothermia.
      A core-temperature of 32 °C is considered the threshold for ventricular fibrillation.
      • Danzl D.F.
      Accidental hypothermia.
      Recommendations. ECG monitoring
      ECG monitoring may be performed with a monitor-defibrillator or an AED. AED monitoring is best with a device that has a monitor window.
      should be applied upon extrication and continued during transport, using maximum amplification if complexes are small (Class I, LOE B).
      Mechanical irritation of hypothermic victims should be minimized, avoiding excessive limb extension, rough transport and unnecessary chest compressions (Class I, LOE B).
      Transport victims in the horizontal position (Class I, LOE C).

      3.3.3 Core-temperature

      Accidental hypothermia has been defined as “an unintentional reduction in core-temperature <35 °C.”
      • Soar J.
      • Perkins G.D.
      • Abbas G.
      • et al.
      European Resuscitation Council Guidelines for Resuscitation 2010 Section 8. Cardiac arrest in special circumstances: Electrolyte abnormalities, poisoning, drowning, accidental hypothermia, hyperthermia, asthma, anaphylaxis, cardiac surgery, trauma, pregnancy, electrocution.
      • Brown D.
      • Brugger H.
      • Boyd J.
      • Paal P.
      Accidental hypothermia.
      • Danzl D.F.
      Accidental hypothermia.
      Hypothermia may be staged using the “Swiss staging” system (based on clinical findings as well as core temperatures),
      • Soar J.
      • Perkins G.D.
      • Abbas G.
      • et al.
      European Resuscitation Council Guidelines for Resuscitation 2010 Section 8. Cardiac arrest in special circumstances: Electrolyte abnormalities, poisoning, drowning, accidental hypothermia, hyperthermia, asthma, anaphylaxis, cardiac surgery, trauma, pregnancy, electrocution.
      • Brown D.
      • Brugger H.
      • Boyd J.
      • Paal P.
      Accidental hypothermia.
      • Durrer B.
      • Brugger H.
      • Syme D.
      International Commission for Mountain Emergency Medicine. The medical on-site treatment of hypothermia: ICAR-MEDCOM recommendation.
      which corresponds with the system of Danzl.
      • Danzl D.F.
      Accidental hypothermia.
      Hypothermia is often combined with asphyxia and trauma, rendering clinical signs unreliable. Oesophageal temperatures are more reliable than other temperatures
      • Hayward J.S.
      • Eckerson J.D.
      • Kemna D.
      Thermal and cardiovascular changes during three methods of resuscitation from mild hypothermia.
      and are recommended in intubated patients.
      • Soar J.
      • Perkins G.D.
      • Abbas G.
      • et al.
      European Resuscitation Council Guidelines for Resuscitation 2010 Section 8. Cardiac arrest in special circumstances: Electrolyte abnormalities, poisoning, drowning, accidental hypothermia, hyperthermia, asthma, anaphylaxis, cardiac surgery, trauma, pregnancy, electrocution.
      • Danzl D.F.
      Accidental hypothermia.
      • Brugger H.
      • Oberhammer R.
      • Adler-Kastner L.
      • Beikircher W.
      The rate of cooling during avalanche burial; a “Core” issue.
      Alternatively, epitympanic temperatures are reasonably accurate in the non-intubated patient not in cardiac arrest, given a non-obstructed ear canal and correct application including insulation from cold air.
      • Brugger H.
      • Durrer B.
      • Adler-Kastner L.
      On-site triage of avalanche victims with asystole by the emergency doctor.
      • Locher T.
      • Merki B.
      • Eggenberger P.
      • Walpoth B.
      • Hilfiker O.
      Measurement of core temperature in the field: comparison of two “tympanic” measuring methods with esophageal temperature.
      In a cold environment only thermistor-based, not infrared-based, epitympanic thermometers correlate well with core-temperature.
      • Locher T.
      • Merki B.
      • Eggenberger P.
      • Walpoth B.
      • Hilfiker O.
      Measurement of core temperature in the field: comparison of two “tympanic” measuring methods with esophageal temperature.
      In human studies epitympanic, brain and bladder temperatures correlated well,
      • Camboni D.
      • Philipp A.
      • Schebesch K.M.
      • Schmid C.
      Accuracy of core temperature measurement in deep hypothermic circulatory arrest.
      while rectal temperatures lagged behind oesophageal temperatures during rewarming.
      • Grissom C.K.
      • Harmston C.H.
      • McAlpine J.C.
      • et al.
      Spontaneous endogenous core temperature rewarming after cooling due to snow burial.
      • Hayward J.S.
      • Eckerson J.D.
      • Kemna D.
      Thermal and cardiovascular changes during three methods of resuscitation from mild hypothermia.
      Recommendations. Don’t rely on clinical hypothermia staging alone when asphyxia and/or trauma occur (Class I, LOE C).
      Obtain core-temperatures when hypothermia has management significance, with an oesophageal probe in the intubated or epitympanic thermistor probe in the non-intubated victim (Class I, LOE B).
      Rectal temperature may be used to gauge hypothermia initially (Class IIa, LOE B).

      3.3.4 Insulation

      Afterdrop refers to continued decline in temperature after removal from cold. All guidelines recommend insulation from further cooling and most recommend removal of wet clothing,
      • Brugger H.
      • Durrer B.
      • Adler-Kastner L.
      • Falk M.
      • Tschirky F.
      Field management of avalanche victims.
      • Brugger H.
      • Durrer B.
      On-site treatment of avalanche victims ICAR-MEDCOM-recommendation.
      • Brown D.
      • Brugger H.
      • Boyd J.
      • Paal P.
      Accidental hypothermia.
      • Danzl D.F.
      Accidental hypothermia.
      which may however increase heat loss in a cold, windy environment. Manikin studies found that increasing insulation over wet clothing produced a similar reduction in heat loss compared to removing clothing
      • Henriksson O.
      • Lundgren P.
      • Kuklane K.
      • Holmer I.
      • Naredi P.
      • Bjornstig U.
      Protection against cold in prehospital care: evaporative heat loss reduction by wet clothing removal or the addition of a vapor barrier: a thermal manikin study.
      and that a windproof outer wrap over the insulation assembly is necessary.
      • Henriksson O.
      • Lundgren J.P.
      • Kuklane K.
      • Holmer I.
      • Bjornstig U.
      Protection against cold in prehospital care-thermal insulation properties of blankets and rescue bags in different wind conditions.
      Recommendations. Hypothermic victims should be insulated against further heat loss with dry, low-conductivity, whole-body assemblies covered in a windproof and water-resistant outer shell
      These may be purpose-built rescue bags with insulated hoods, or assemblies of blankets enclosed in aluminium foil combined with head protection.
      (Class I, LOE B).
      Remove wet clothing only if the victim can be insulated effectively; cut clothing cautiously if victim has a hypothermia staging of moderate or worse (Class I, LOE C).

      3.3.5 Out-of-hospital rewarming

      Applying heat packs may improve comfort although core-temperature may not be increased.
      • Lundgren P.
      • Henriksson O.
      • Naredi P.
      • Bjornstig U.
      The effect of active warming in prehospital trauma care during road and air ambulance transportation - a clinical randomized trial.
      Warmed humidified oxygen provides limited benefit.
      • Soar J.
      • Perkins G.D.
      • Abbas G.
      • et al.
      European Resuscitation Council Guidelines for Resuscitation 2010 Section 8. Cardiac arrest in special circumstances: Electrolyte abnormalities, poisoning, drowning, accidental hypothermia, hyperthermia, asthma, anaphylaxis, cardiac surgery, trauma, pregnancy, electrocution.
      • Vanden Hoek T.L.
      • Morrison L.J.
      • Shuster M.
      • et al.
      Part 12: cardiac arrest in special situations: 2010 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care.
      Warmed infused fluids provide only minimal contribution to rewarming, with a hypothetical rise of 0.3 °C L−1 of 40 °C fluid,
      • Paal P.
      • Beikircher W.
      • Brugger H.
      Avalanche emergencies. Review of the current situation.
      and are difficult to keep warm in the field.
      Recommendations. Apply safe heat sources such as covered chemical heat packs to the trunk (Class IIb, LOE B).
      Maintain infusate at 38–42 °C (Class IIb, LOE B).

      3.3.6 Oxygen

      Adequate oxygenation may help reduce the risk of post-rescue collapse as it is known to improve myocardial stability.
      • Danzl D.F.
      Accidental hypothermia.
      Pulse-oximetry is inaccurate with cold exposure due to peripheral vasoconstriction as well as device malfunction, high altitude and bright ambient light.
      • Luks A.M.
      • Swenson E.R.
      Pulse oximetry at high altitude.
      Recommendations. Apply supplemental oxygen to significantly hypothermic victims (Class IIb, LOE C).
      Pulse-oximetry may be unreliable (Class IIb, LOE B).

      3.3.7 Advanced airway

      Advanced airway placement provides oxygenation and airway protection from aspiration and is low risk for triggering malignant arrhythmias.
      • Danzl D.F.
      • Pozos R.S.
      • Auerbach P.S.
      • et al.
      Multicenter hypothermia survey.
      Depolarizing neuromuscular paralytics (e.g. succinylcholine) may increase the serum potassium level and affect subsequent decisions.
      Recommendation. Consider the impact of depolarizing paralytics on serum potassium if the latter is planned for resuscitation or advanced rewarming decisions (Class I, LOE B).

      3.3.8 CPR

      In severely hypothermic patients respirations and pulse may be indistinct.
      Recommendations. Check carefully for vital signs and ECG activity for up to 1 min (Class IIb, LOE C).
      Initiate CPR if signs of life are absent at standard BLS rates (Class IIa, LOE B).

      3.3.9 Defibrillation

      Defibrillation of severely hypothermic patients (<28 °C) presenting with ventricular fibrillation is unsuccessful in most cases, though defibrillation thresholds vary individually and successful defibrillation with core-temperatures as low as 25.6 °C has been reported.
      • Thomas R.
      • Cahill C.J.
      Successful defibrillation in profound hypothermia (core body temperature 25.6 °C).
      Due to the paucity of animal and human studies and conflicting results, experts disagree on the application of defibrillation with core-temperatures <30 °C.
      • Soar J.
      • Perkins G.D.
      • Abbas G.
      • et al.
      European Resuscitation Council Guidelines for Resuscitation 2010 Section 8. Cardiac arrest in special circumstances: Electrolyte abnormalities, poisoning, drowning, accidental hypothermia, hyperthermia, asthma, anaphylaxis, cardiac surgery, trauma, pregnancy, electrocution.
      • Vanden Hoek T.L.
      • Morrison L.J.
      • Shuster M.
      • et al.
      Part 12: cardiac arrest in special situations: 2010 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care.
      The 2010 ERC-guidelines
      • Soar J.
      • Perkins G.D.
      • Abbas G.
      • et al.
      European Resuscitation Council Guidelines for Resuscitation 2010 Section 8. Cardiac arrest in special circumstances: Electrolyte abnormalities, poisoning, drowning, accidental hypothermia, hyperthermia, asthma, anaphylaxis, cardiac surgery, trauma, pregnancy, electrocution.
      recommend a maximum of three defibrillations at <30 °C while the 2010 AHA-guidelines
      • Vanden Hoek T.L.
      • Morrison L.J.
      • Shuster M.
      • et al.
      Part 12: cardiac arrest in special situations: 2010 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care.
      recommend standard defibrillation while rewarming.
      Recommendations. Use standard defibrillations when indicated, regardless of core-temperature; repetitions beyond three attempts may be delayed until core-temperature >30 °C and should be avoided if they cause interruption of CPR and/or transport to rewarming (see Transport) (Class IIa, LOE B).

      3.3.10 ALS medications

      Similar to defibrillation, experts disagree on the effectiveness of advanced life support (ALS) drug therapy with core-temperatures <30 °C.
      • Soar J.
      • Perkins G.D.
      • Abbas G.
      • et al.
      European Resuscitation Council Guidelines for Resuscitation 2010 Section 8. Cardiac arrest in special circumstances: Electrolyte abnormalities, poisoning, drowning, accidental hypothermia, hyperthermia, asthma, anaphylaxis, cardiac surgery, trauma, pregnancy, electrocution.
      • Vanden Hoek T.L.
      • Morrison L.J.
      • Shuster M.
      • et al.
      Part 12: cardiac arrest in special situations: 2010 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care.
      The 2010 ERC-guidelines
      • Soar J.
      • Perkins G.D.
      • Abbas G.
      • et al.
      European Resuscitation Council Guidelines for Resuscitation 2010 Section 8. Cardiac arrest in special circumstances: Electrolyte abnormalities, poisoning, drowning, accidental hypothermia, hyperthermia, asthma, anaphylaxis, cardiac surgery, trauma, pregnancy, electrocution.
      recommend no ALS drugs, while the 2010 AHA-guidelines
      • Vanden Hoek T.L.
      • Morrison L.J.
      • Shuster M.
      • et al.
      Part 12: cardiac arrest in special situations: 2010 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care.
      allow vasopressors in cardiac arrest. Vasopressors may induce arrhythmias and increase risk of frostbite. Drug metabolism is decreased with low core-temperature.
      • Heier T.
      • Caldwell J.E.
      Impact of hypothermia on the response to neuromuscular blocking drugs.
      Recommendation. It may be reasonable to consider vasopressors concurrently with rewarming strategies (Class IIb, LOE B).

      3.3.11 Transport

      For hypothermic victims with a perfusing rhythm, active external rewarming such as forced-air rewarming is successful.
      • Soar J.
      • Perkins G.D.
      • Abbas G.
      • et al.
      European Resuscitation Council Guidelines for Resuscitation 2010 Section 8. Cardiac arrest in special circumstances: Electrolyte abnormalities, poisoning, drowning, accidental hypothermia, hyperthermia, asthma, anaphylaxis, cardiac surgery, trauma, pregnancy, electrocution.
      • Vanden Hoek T.L.
      • Morrison L.J.
      • Shuster M.
      • et al.
      Part 12: cardiac arrest in special situations: 2010 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care.
      • Danzl D.F.
      Accidental hypothermia.
      For severely hypothermic victims in cardiac arrest, extracorporeal rewarming resulted in return of spontaneous circulation (ROSC) in 23 of 186 and survival to hospital discharge in 8 of 186 avalanche victims examined in a systematic review of seven case series and reports.
      • Boyd J.
      • Brugger H.
      • Shuster M.
      Prognostic factors in avalanche resuscitation: a systematic review.
      Complications after extracorporeal rewarming commonly include pulmonary oedema,
      • Oberhammer R.
      • Beikircher W.
      • Hormann C.
      • et al.
      Full recovery of an avalanche victim with profound hypothermia and prolonged cardiac arrest treated by extracorporeal re-warming.
      • Ruttmann E.
      • Weissenbacher A.
      • Ulmer H.
      • et al.
      Prolonged extracorporeal membrane oxygenation-assisted support provides improved survival in hypothermic patients with cardiocirculatory arrest.
      which may explain improved survival with extracorporeal membrane oxygenation (ECMO) compared to cardiopulmonary bypass (CPB).
      • Ruttmann E.
      • Weissenbacher A.
      • Ulmer H.
      • et al.
      Prolonged extracorporeal membrane oxygenation-assisted support provides improved survival in hypothermic patients with cardiocirculatory arrest.
      Recommendations. For victims with core-temperature <32 °C but no cardiac instability, i.e. systolic blood pressure ≥90 mmHg and no ventricular arrhythmias, and core-temperature >28 °C, transport to the nearest appropriate hospital for active external and minimally invasive rewarming (i.e. warm environment; chemical, electrical, or forced air heating packs or blankets; warm iv-fluids) is recommended
      • Brown D.
      • Brugger H.
      • Boyd J.
      • Paal P.
      Accidental hypothermia.
      (Class I, LOE B).
      Hypothermic victims with a patent or unknown airway, with cardiac instability or a core-temperature <28 °C, or in cardiac arrest, should be transported to a centre with ECMO or CPB; if ECMO/CPB is not available transport to an appropriate hospital for alternative active internal rewarming (e.g. thoracic lavage) with continued CPR is recommended (Class I, LOE B).
      Notify the ECMO/CPB centre before departure (Class IIa, LOE C).

      3.3.12 Serum potassium

      Serum potassium was predictive of survival for hypothermic cardiac arrest victims in a systematic review of prognostic factors in avalanche resuscitation,
      • Boyd J.
      • Brugger H.
      • Shuster M.
      Prognostic factors in avalanche resuscitation: a systematic review.
      with higher levels and poorer survival in asphyxiated victims. The highest admission serum potassium with ROSC was 8 mmol L−1,
      • Mair P.
      • Kornberger E.
      • Furtwaengler W.
      • Balogh D.
      • Antretter H.
      Prognostic markers in patients with severe accidental hypothermia and cardiocirculatory arrest.
      while the highest level with survival was 6.4 mmol L−1.
      • Locher T.
      • Walpoth B.
      Differential diagnosis of circulatory failure in hypothermic avalanche victims: retrospective analysis of 32 avalanche accidents.
      In accidental hypothermia of any origin the highest admission potassium of a survivor was 11.8 mmol L−1 in a 31-month-old child exposed to freezing weather.
      • Dobson J.
      • Burgess J.
      Resuscitation of severe hypothermia by extracorporeal rewarming in a child.
      Recommendations. For hypothermic victims in asystolic cardiac arrest where duration of burial or airway patency is unknown or where a decision for prolonged resuscitation or long transport to a centre for ECMO/CPB needs confirmation, a serum potassium <8 mmol L−1 would indicate continued action, >12 mmol L−1 would indicate termination of resuscitation and 8–12 mmol L−1 in an adult victim should be considered with other factors (Class I, LOE A).

      3.3.13 Prognosis

      Asphyxia markedly reduces survival in hypothermic cardiac arrest despite extracorporeal rewarming.
      • Schaller M.D.
      • Fischer A.P.
      • Perret C.H.
      • Hyperkalemia
      A prognostic factor during acute severe hypothermia.
      • Locher T.
      • Walpoth B.
      • Pfluger D.
      • Althaus U.
      Accidental hypothermia in Switzerland (1980–1987)—case reports and prognostic factors.
      • Mair P.
      • Kornberger E.
      • Furtwaengler W.
      • Balogh D.
      • Antretter H.
      Prognostic markers in patients with severe accidental hypothermia and cardiocirculatory arrest.
      • Ruttmann E.
      • Weissenbacher A.
      • Ulmer H.
      • et al.
      Prolonged extracorporeal membrane oxygenation-assisted support provides improved survival in hypothermic patients with cardiocirculatory arrest.
      The lowest core-temperature reported to date for a survivor of accidental hypothermia is 13.7 °C in a victim trapped in a waterfall gully
      • Gilbert M.
      • Busund R.
      • Skagseth A.
      • Nilsen P.A.
      • Solbo J.P.
      Resuscitation from accidental hypothermia of 13.7 °C with circulatory arrest.
      and 19 °C in a victim of avalanche burial.
      • Althaus U.
      • Aeberhard P.
      • Schupbach P.
      • Nachbur B.H.
      • Muhlemann W.
      Management of profound accidental hypothermia with cardiorespiratory arrest.
      Recommendation. Victims of hypothermic cardiac arrest found with a patent or unknown airway and who are otherwise deemed possible survivors should be resuscitated until rewarmed to a core-temperature >32 °C before a final decision is made (Class I, LOE C).

      3.4 General measures

      3.4.1 Oral fluids

      Two Cochrane Systematic Reviews and the practice guideline of the American Society of Anesthesiologists found no evidence of adverse effects from clear fluids up to 2 h prior to surgery in otherwise healthy patients with no abnormal risk of regurgitation or aspiration.
      • American Society of Anesthesiologists Committee
      Practice guidelines for preoperative fasting and the use of pharmacologic agents to reduce the risk of pulmonary aspiration: application to healthy patients undergoing elective procedures: an updated report by the American Society of Anesthesiologists Committee on Standards and Practice Parameters.
      Recommendations. Alert victims not requiring sedation or anaesthesia within 2 h may drink warmed, clear, calorie-containing, non-alcoholic, non-caffeinated fluids to sustain hydration and spontaneous rewarming (Class IIb, LOE B).

      3.4.2 Activity

      Recommendation. Alert mildly hypothermic victims (35–32 °C) may exercise to rewarm (Class IIa, LOE C).

      3.4.3 Organized rescue

      Recommendations. Organized rescue teams should mobilize promptly, ideally by helicopter, and should include clinicians skilled in mountain emergency medicine and be staffed according to the number of buried victims (Class IIa, LOE C).
      Dogs and handlers may accompany organized rescue teams to find completely buried victims. Once all victims have been located there is no use for dogs and handlers (Class IIa, LOE C).
      All staff should have appropriate safety equipment, especially avalanche transceivers and airbags (Class I, LOE B).
      Medical equipment should include core-temperature and ECG monitor/defibrillator devices and appropriate medications; all instruments should be insulated and have fully-charged batteries (Class I, LOE B).
      The potential risk to the rescuers must be evaluated, taking less risk after longer burials (Class IIb, LOE C).

      3.4.4 Triage

      A multiple casualty incident may initially overwhelm rescuers, and limited resources should be allocated to those most likely to survive.
      • Bogle L.B.
      • Boyd J.J.
      • McLaughlin K.A.
      Triaging multiple victims in an avalanche setting: the Avalanche Survival Optimizing Rescue Triage algorithmic approach.
      Recommendations. When resources are overwhelmed by multiple victims in cardiac arrest priority should be given to those with a cardiac rhythm, a higher core-temperature and other favourable factors (Class IIb, LOE B).

      3.5 Termination of CPR

      The very poor survival of patients suffering prehospital normothermic asystolic cardiac arrest has resulted in validated EMS termination-of-resuscitation rules that have been incorporated into a guideline for mountain rescue (Class IIb, LOE C).
      • Paal P.
      • Milani M.
      • Brown D.
      • Boyd J.
      • Ellerton J.
      Termination of cardiopulmonary resuscitation in mountain rescue.
      Recommendations. Resuscitation may be terminated (or withheld) when rescuer safety is unacceptably high, lethal injuries such as decapitation or truncal transection have occurred, the body is completely frozen, a valid do-not-resuscitate order exists, or limitations in transport or other logistics render resuscitation futile (Class I, LOE C).
      Resuscitation may be terminated in unwitnessed cardiac arrest when, after 20 min of resuscitation, there has been no ROSC with no shock advised by AED or only asystole seen on ECG with no hypothermia or other special circumstance warranting extended CPR (Class IIa, LOE A).

      4. Conclusions

      The algorithm for the management of avalanche victims is shown in Fig. 2. If lethal injuries are excluded and the body is not frozen, the rescue strategy is governed by the duration of snow burial and, if not available, by the victim's core-temperature. If burial time ≤35 min (or core-temperature ≥32 °C) rapid extrication and standard ALS is important. If burial time >35 min and core-temperature <32 °C, treatment of hypothermia including gentle extrication, full body insulation, ECG and core-temperature monitoring is recommended, as well as advanced airway management if appropriate. Unresponsive patients presenting with vital signs should be transported to a hospital capable of active external and minimally invasive rewarming such as forced air rewarming. Patients with cardiac instability or in cardiac arrest (with a patent airway) should be transported with uninterrupted CPR to an ECMO/CPB rewarming centre. Management should include spinal precautions and other trauma care as indicated.

      Conflicts of interest statement

      None of the authors have a commercial or industrial conflict of interest. H.B., J.B., B.D., P.P. and K.Z. have published on hypothermia. H.B. receives support as the head of the Institute of Mountain Emergency Medicine, EURAC research.

      Acknowledgements

      The following ICAR MEDCOM members approved these recommendations at meetings in Longyearbyan (Norway) and Åre (Sweden): Gege Agazzi (Italy); Borislav Aleraj (Croatia); Jeff Boyd (Canada); Bruce Brink (Canada); Douglas Brown (Canada); Hermann Brugger (Italy); Perilif Eduinsson (Sweden); Tore Dahlberg (Norway); John Ellerton (Vice-President, United Kindom); Fidel Elsensohn (President, Austria); Herbert Forster (Germany); Nicole Gantner-Vogt (Principality of Liechtenstein); Andrzod Gorka (Poland); Martin Ivanov (Bulgaria); Alex Kottmann (Switzerland); Xavier Ledoux (France); Volker Lischke (Germany); Mario Milani (Italy); Maria Mizuskovic (Montenegro); Josè Ramòn Morandeira (Spain); Wokiech Moskal (Poland); Maria Antonia Nerin (Spain); Marie Nordgren (Sweden); Einar Ornarnarrson (Iceland); Noriyoshi Ohashi (Japan); Kazue Oshiro (Japan); Peter Paal (Austria); Oliver Reisten (Switzerland); Erik Sandstrom (Sweden); Frederik Sederkuist (Sweden); Haris Sinifakoulis (Greece); Sven Christjar Skaiaa (Norway); Inigo Soteras (Spain); Giacomo Strapazzon (Italy); Günther Sumann (Austria); Oleg Tcholakov (Bulgaria); David Tingay (Australia); Iztok Tomazin (Slovenia); Heidi Vigerust (Norway); David Watson (Canada); Eveline Winterberger (Switzerland); Ken Zafren (Vice-President, USA); Gregoire Zen-Ruffinen (Switzerland). We thank Emily Procter for the help in editing the manuscript.

      Appendix A. Supplementary data

      References

        • Etter H.J.
        Report of the avalanche subcommission at the general meeting of the international commission for Alpine rescue. 2010
        • Stethem C.
        • Jamieson B.
        • Schaerer P.
        • Liverman D.
        • German D.
        • Walker S.
        Snow avalanche hazard in Canada – a review.
        Nat Hazards. 2003; 28: 487-515
        • Falk M.
        • Brugger H.
        • Adler-Kastner L.
        Avalanche survival chances.
        Nature. 1994; 368: 21
        • Brugger H.
        • Durrer B.
        • Adler-Kastner L.
        • Falk M.
        • Tschirky F.
        Field management of avalanche victims.
        Resuscitation. 2001; 51: 7-15
        • Althaus U.
        • Aeberhard P.
        • Schupbach P.
        • Nachbur B.H.
        • Muhlemann W.
        Management of profound accidental hypothermia with cardiorespiratory arrest.
        Ann Surg. 1982; 195: 492-495
        • Schaller M.D.
        • Fischer A.P.
        • Perret C.H.
        • Hyperkalemia
        A prognostic factor during acute severe hypothermia.
        JAMA. 1990; 264: 1842-1845
        • Locher T.
        • Walpoth B.
        • Pfluger D.
        • Althaus U.
        Accidental hypothermia in Switzerland (1980–1987)—case reports and prognostic factors.
        Schweiz Med Wochenschr. 1991; 121: 1020-1028
        • Mair P.
        • Kornberger E.
        • Furtwaengler W.
        • Balogh D.
        • Antretter H.
        Prognostic markers in patients with severe accidental hypothermia and cardiocirculatory arrest.
        Resuscitation. 1994; 27: 47-54
        • Walpoth B.H.
        • Walpoth-Aslan B.N.
        • Mattle H.P.
        • et al.
        Outcome of survivors of accidental deep hypothermia and circulatory arrest treated with extracorporeal blood warming.
        N Engl J Med. 1997; 337: 1500-1505
        • Brugger H.
        • Durrer B.
        • Adler-Kastner L.
        On-site triage of avalanche victims with asystole by the emergency doctor.
        Resuscitation. 1996; 31: 11-16
        • Brugger H.
        • Durrer B.
        On-site treatment of avalanche victims ICAR-MEDCOM-recommendation.
        High Alt Med Biol. 2002; 3: 421-425
        • Boyd J.
        • Brugger H.
        • Shuster M.
        Prognostic factors in avalanche resuscitation: a systematic review.
        Resuscitation. 2010; 81: 645-652
        • Soar J.
        • Perkins G.D.
        • Abbas G.
        • et al.
        European Resuscitation Council Guidelines for Resuscitation 2010 Section 8. Cardiac arrest in special circumstances: Electrolyte abnormalities, poisoning, drowning, accidental hypothermia, hyperthermia, asthma, anaphylaxis, cardiac surgery, trauma, pregnancy, electrocution.
        Resuscitation. 2010; 81: 1400-1433
        • Vanden Hoek T.L.
        • Morrison L.J.
        • Shuster M.
        • et al.
        Part 12: cardiac arrest in special situations: 2010 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care.
        Circulation. 2010; 122: S829-S861
        • Brown D.
        • Brugger H.
        • Boyd J.
        • Paal P.
        Accidental hypothermia.
        New Engl J Med. 2012; 367: 1930-1938
        • Boyd J.
        • Haegeli P.
        • Abu-Laban R.B.
        • Shuster M.
        • Butt J.C.
        Patterns of death among avalanche fatalities: a 21-year review.
        CMAJ. 2009; 180: 507-512
        • Haegeli P.
        • Falk M.
        • Brugger H.
        • Etter H.J.
        • Boyd J.
        Comparison of avalanche survival patterns in Canada and Switzerland.
        CMAJ. 2011; 183: 789-795
        • Brugger H.
        • Sumann G.
        • Meister R.
        • et al.
        Hypoxia and hypercapnia during respiration into an artificial air pocket in snow: implications for avalanche survival.
        Resuscitation. 2003; 58: 81-88
        • Hohlrieder M.
        • Brugger H.
        • Schubert H.M.
        • Pavlic M.
        • Ellerton J.
        • Mair P.
        Pattern and severity of injury in avalanche victims.
        High Alt Med Biol. 2007; 8: 56-61
        • McIntosh S.E.
        • Grissom C.K.
        • Olivares C.R.
        • Kim H.S.
        • Tremper B.
        Cause of death in avalanche fatalities.
        Wilderness Environ Med. 2007; 18: 293-297
        • Grissom C.K.
        • Radwin M.I.
        • Harmston C.H.
        • Hirshberg E.L.
        • Crowley T.J.
        Respiration during snow burial using an artificial air pocket.
        JAMA. 2000; 283: 2266-2271
        • Radwin M.I.
        • Grissom C.K.
        • Scholand M.B.
        • Harmston C.H.
        Normal oxygenation and ventilation during snow burial by the exclusion of exhaled carbon dioxide.
        Wilderness Environ Med. 2001; 12: 256-262
        • Paal P.
        • Strapazzon G.
        • Braun P.
        • et al.
        Factors affecting survival from avalanche burial—a randomized prospective porcine pilot study.
        Resuscitation. 2012; ([Epub ahead of print])
        • Bernhard M.
        • Bottiger B.W.
        Out-of-hospital endotracheal intubation of trauma patients: straight back and forward to the gold standard!.
        Eur J Anaesthesiol. 2011; 28: 75-76
        • Neumar R.W.
        • Otto C.W.
        • Link M.S.
        • et al.
        Part 8: adult advanced cardiovascular life support: 2010 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care.
        Circulation. 2010; 122: S729-S767
        • Deakin C.D.
        • Nolan J.P.
        • Soar J.
        • et al.
        European Resuscitation Council Guidelines for Resuscitation 2010 Section 4. Adult advanced life support.
        Resuscitation. 2010; 81: 1305-1352
        • Schmid F.
        [The pathogenesis of pulmonary edema after being buried by an avalanche].
        Schweiz Med Wochenschr. 1981; 111: 1441-1445
        • Kragh Jr., J.F.
        • Walters T.J.
        • Baer D.G.
        • et al.
        Survival with emergency tourniquet use to stop bleeding in major limb trauma.
        Ann Surg. 2009; 249: 1-7
        • Davis D.P.
        • Peay J.
        • Sise M.J.
        • et al.
        Prehospital airway and ventilation management: a trauma score and injury severity score-based analysis.
        J Trauma. 2010; 69: 294-301
        • Gilbert M.
        • Busund R.
        • Skagseth A.
        • Nilsen P.A.
        • Solbo J.P.
        Resuscitation from accidental hypothermia of 13.7 °C with circulatory arrest.
        Lancet. 2000; 355: 375-376
        • Oberhammer R.
        • Beikircher W.
        • Hormann C.
        • et al.
        Full recovery of an avalanche victim with profound hypothermia and prolonged cardiac arrest treated by extracorporeal re-warming.
        Resuscitation. 2008; 76: 474-480
        • Grissom C.K.
        • Radwin M.I.
        • Scholand M.B.
        • Harmston C.H.
        • Muetterties M.C.
        • Bywater T.J.
        Hypercapnia increases core temperature cooling rate during snow burial.
        J Appl Physiol. 2004; 96: 1365-1370
        • Locher T.
        • Walpoth B.
        Differential diagnosis of circulatory failure in hypothermic avalanche victims: retrospective analysis of 32 avalanche accidents.
        Schweiz Rundsch Med Prax. 1996; 85: 1275-1282
        • Putzer G.
        • Schmid S.
        • Braun P.
        • Brugger H.
        • Paal P.
        Cooling of six centigrades in an hour during avalanche burial.
        Resuscitation. 2010; 81: 1043-1044
        • Strapazzon G.
        • Beikircher W.
        • Procter E.
        • Brugger H.
        Electrical heart activity recorded during prolonged avalanche burial.
        Circulation. 2012; 125: 646-647
        • Grissom C.K.
        • Harmston C.H.
        • McAlpine J.C.
        • et al.
        Spontaneous endogenous core temperature rewarming after cooling due to snow burial.
        Wilderness Environ Med. 2010; 21: 229-235
        • Grueskin J.
        • Tanen D.A.
        • Harvey P.
        • Santos F.D.
        • Richardson III, W.H.
        • Riffenburgh R.H.
        A pilot study of mechanical stimulation and cardiac dysrhythmias in a porcine model of induced hypothermia.
        Wilderness Environ Med. 2007; 18: 133-137
        • Danzl D.F.
        Accidental hypothermia.
        in: Auerbach P.S. Wilderness medicine. 6th ed. Mosby, Philadelphia2012: 116-142
        • Durrer B.
        • Brugger H.
        • Syme D.
        International Commission for Mountain Emergency Medicine. The medical on-site treatment of hypothermia: ICAR-MEDCOM recommendation.
        High Alt Med Biol. 2003; 4: 99-103
        • Hayward J.S.
        • Eckerson J.D.
        • Kemna D.
        Thermal and cardiovascular changes during three methods of resuscitation from mild hypothermia.
        Resuscitation. 1984; 11: 21-33
        • Brugger H.
        • Oberhammer R.
        • Adler-Kastner L.
        • Beikircher W.
        The rate of cooling during avalanche burial; a “Core” issue.
        Resuscitation. 2009; 80: 956-958
        • Locher T.
        • Merki B.
        • Eggenberger P.
        • Walpoth B.
        • Hilfiker O.
        Measurement of core temperature in the field: comparison of two “tympanic” measuring methods with esophageal temperature.
        in: Proceedings International Congress of Mountain Medicine, Francois-Xavier Bagnoud1997: 56
        • Camboni D.
        • Philipp A.
        • Schebesch K.M.
        • Schmid C.
        Accuracy of core temperature measurement in deep hypothermic circulatory arrest.
        Interact Cardiovasc Thorac Surg. 2008; 7: 922-924
        • Henriksson O.
        • Lundgren P.
        • Kuklane K.
        • Holmer I.
        • Naredi P.
        • Bjornstig U.
        Protection against cold in prehospital care: evaporative heat loss reduction by wet clothing removal or the addition of a vapor barrier: a thermal manikin study.
        Prehosp Disaster Med. 2012; 27: 53-58
        • Henriksson O.
        • Lundgren J.P.
        • Kuklane K.
        • Holmer I.
        • Bjornstig U.
        Protection against cold in prehospital care-thermal insulation properties of blankets and rescue bags in different wind conditions.
        Prehosp Disaster Med. 2009; 24: 408-415
        • Lundgren P.
        • Henriksson O.
        • Naredi P.
        • Bjornstig U.
        The effect of active warming in prehospital trauma care during road and air ambulance transportation - a clinical randomized trial.
        Scand J Trauma Resusc Emerg Med. 2011; 19: 59
        • Paal P.
        • Beikircher W.
        • Brugger H.
        Avalanche emergencies. Review of the current situation.
        Anaesthesist. 2006; 55: 314-324
        • Luks A.M.
        • Swenson E.R.
        Pulse oximetry at high altitude.
        High Alt Med Biol. 2011; 12: 109-119
        • Danzl D.F.
        • Pozos R.S.
        • Auerbach P.S.
        • et al.
        Multicenter hypothermia survey.
        Ann Emerg Med. 1987; 16: 1042-1055
        • Thomas R.
        • Cahill C.J.
        Successful defibrillation in profound hypothermia (core body temperature 25.6 °C).
        Resuscitation. 2000; 47: 317-320
        • Heier T.
        • Caldwell J.E.
        Impact of hypothermia on the response to neuromuscular blocking drugs.
        Anesthesiology. 2006; 104: 1070-1080
        • Ruttmann E.
        • Weissenbacher A.
        • Ulmer H.
        • et al.
        Prolonged extracorporeal membrane oxygenation-assisted support provides improved survival in hypothermic patients with cardiocirculatory arrest.
        J Thorac Cardiovasc Surg. 2007; 134: 594-600
        • Dobson J.
        • Burgess J.
        Resuscitation of severe hypothermia by extracorporeal rewarming in a child.
        J Trauma. 1996; 40: 483-485
        • American Society of Anesthesiologists Committee
        Practice guidelines for preoperative fasting and the use of pharmacologic agents to reduce the risk of pulmonary aspiration: application to healthy patients undergoing elective procedures: an updated report by the American Society of Anesthesiologists Committee on Standards and Practice Parameters.
        Anesthesiology. 2011; 114: 495-511
        • Bogle L.B.
        • Boyd J.J.
        • McLaughlin K.A.
        Triaging multiple victims in an avalanche setting: the Avalanche Survival Optimizing Rescue Triage algorithmic approach.
        Wilderness Environ Med. 2010; 21: 28-34
        • Paal P.
        • Milani M.
        • Brown D.
        • Boyd J.
        • Ellerton J.
        Termination of cardiopulmonary resuscitation in mountain rescue.
        High Alt Med Biol. 2012; 13: 200-208
        • Canadian Avalanche Association
        Observation guidelines and recording standards for weather, snowpack and avalanches.
        Canadian Avalanche Association, Revelstoke, Canada2007
        • Greene E.
        • Atkins D.
        • Birkeland K.
        • et al.
        Snow, weather, and avalanches: observational guidelines for Avalanche Programs in the United States.
        American Avalanche Association, Pagosa Springs, CO2010