Resuscitation 89 (2015) 114–118
Contents lists available at ScienceDirect
Resuscitation journal homepage: www.elsevier.com/locate/resuscitation
Clinical Paper
Outcome of avalanche victims with out-of-hospital cardiac arrest夽 Luca Moroder a , Birgit Mair a,b , Hermann Brugger c , Wolfgang Voelckel b,d , Peter Mair a,b,∗ a
Department of Anaesthesiology and Critical Care Medicine, Medical University of Innsbruck, Anichstrasse 35, 6020 Innsbruck, Austria Christophorus Emergency Medical Helicopter Service, Schubertring 1-3, 1010 Vienna, Austria c Institute of Mountain Emergency Medicine, EURAC Research, Viale Druso 1, 39100 Bolzano, Italy d Department of Anesthesiology and Critical Care Medicine, AUVA Trauma Hospital Salzburg, Dr.-Franz-Rehrl-Platz 4, 5010 Salzburg, Austria b
a r t i c l e
i n f o
Article history: Received 28 November 2014 Received in revised form 13 January 2015 Accepted 16 January 2015 Keywords: Cardiopulmonary resuscitation Avalanche Asphyxia Outcome Bystander
a b s t r a c t Study background: Previous studies focused on the outcome of avalanche victims with out-of-hospital cardiac arrest (OHCA) after long duration of burial (>35 min); the outcome of victims with short duration (≤35 min) remains obscure. Aim of the study: To investigate outcome of avalanche victims with OHCA. Methods: Retrospective analysis of avalanche victims with OHCA between 2008 and 2013 in the Tyrolean Alps. Results: 55 avalanche victims were identified, 32 of whom were declared dead after extrication without cardiopulmonary resuscitation (CPR), all with long duration of burial. In the remaining 23 CPR was initiated at scene; three were partially and 20 completely buried, nine of whom suffered short and 11 long duration of burial. All nine victims with short duration of burial underwent restoration of spontaneous circulation (ROSC) at scene, four of them after bystander CPR, five after advanced life support by the emergency physician. Two patients with ROSC after short duration of burial and bystander CPR survived to hospital discharge with cerebral performance category 1. None of the 11 victims with long duration of burial survived to hospital discharge, although six were transported to hospital with ongoing CPR and three were supported with extracorporeal circulation. Conclusions: In this case series survival with favourable neurological outcome was observed in avalanche victims with short duration of burial only if bystander CPR was immediately performed and ROSC achieved. Strategies for reducing avalanche mortality should focus on prompt extrication from the snow and immediate bystander CPR by uninjured companions. © 2015 Elsevier Ireland Ltd. All rights reserved.
1. Introduction Several publications have highlighted the possibility of survival in avalanche victims with long duration of complete burial and outof-hospital cardiac arrest (OHCA) due to the protective effects of accidental hypothermia that can develop after more than 35 min snow burial.1–3 Recommendations for the triage and management of arrested avalanche victims with duration of burial exceeding 35 min have been published.4 Asphyxia, however, is considered the main underlying pathology for cardiac arrest, while hypothermia is a rare reason for cardiac arrest in avalanche accidents.5–7 With the use of avalanche transceivers many completely buried
夽 A Spanish translated version of the abstract of this article appears as Appendix in the final online version at http://dx.doi.org/10.1016/j.resuscitation.2015.01.019. ∗ Corresponding author at: Department of Anaesthesiology and Critical Care Medicine, Medical University of Innsbruck, Anichstrasse 35, 6020 Innsbruck, Austria. E-mail address: [email protected] (P. Mair). http://dx.doi.org/10.1016/j.resuscitation.2015.01.019 0300-9572/© 2015 Elsevier Ireland Ltd. All rights reserved.
victims can be extricated from the snow within less than 35 min and resuscitated by bystanders, if necessary.6,8,9 The outcome of patients presenting with OHCA after short duration of burial (up to 35 min) has not yet been studied. In such cases asphyxia or trauma, but not hypothermia, may be the cause of cardiac arrest.5,6,9,10 The current study evaluated the pre-hospital and in-hospital resuscitation measures and outcome of patients with OHCA in a consecutive series of avalanche victims.
2. Methods After Ethics Committee approval all rescue missions conducted for avalanche accidents in the Austrian state of Tyrol during five consecutive winter seasons (October 2008 to June 2013) were reviewed. Rescue missions involving at least one victim with OHCA were identified and included in this retrospective observational study.
L. Moroder et al. / Resuscitation 89 (2015) 114–118
115
Table 1 Patient characteristics and outcome of partially buried avalanche victims (n = 3) with out-of-hospital cardiac arrest. CT* (◦ C)
pH*
Lactate* (mmol L−1 )
Potassium* (mmol L−1 )
Outcome
Cause of death
Remarks
–
Died on scene Died after 2 days
Multisystem trauma Brain injury, spinal shock Intractable bleeding
ALS stopped on scene Spine fracture C1 /C2 , spinal cord lesion, brain oedema Multisystem trauma, rewarming with ECMO
Patient
Rhythm
Male, 38 years#
PEA
–
Male, 33 years
PEA
30
7.00
12.4
3.6
Male, 49 years#
VF
22
6.95
10.0
3.8
–
–
Died after 5h
# Witnessed cardiac arrest, PEA = pulseless electrical activity, VF = ventricular fibrillation, CT = core body temperature, * at hospital admission, ALS = advanced life support by emergency physician, ECMO = extracorporeal membrane oxygenation.
Data on accident and rescue mission characteristics were retrieved from accident reports of the Tyrolean Avalanche Forecast Centre and from mission protocols of the rescue services involved. Data included date and location of the avalanche accident, burial status of the victims (partially buried, completely buried), type of rescue for completely buried victims (bystander rescue or rescue by the organized rescue team) and duration of burial. A victim was considered partially buried when his head was unburied and the victim was able to breath. A victim was considered completely buried when his head was under the snow and he was at risk of suffocating. Duration of burial is considered short for durations up to 35 min and long if duration exceeds 35 min. Medical parts of the mission protocols were reviewed by two of the authors (L.M., P.M.) to retrieve available information concerning the victim’s medical condition and pre-hospital therapy. Pre-hospital data included circumstances of cardiac arrest (witnessed, unwitnessed), type of CPR (no CPR, bystander CPR, advanced life support [ALS] by an emergency physician) and outcome of pre-hospital CPR efforts (terminated at scene, ongoing CPR until hospital admission, ROSC after bystander CPR or ROSC after ALS by an emergency physician). In-hospital data included termination of CPR, duration of intensive care unit stay, transfer from outside hospital to Innsbruck Medical University Hospital and survival and neurological outcome using the Cerebral Performance Category Scale. In addition, for all patients admitted to Innsbruck Medical University systolic blood pressure, core temperature, pH (not temperature corrected), serum potassium and serum lactate concentrations and whole body computed tomography (CT) scan findings on admission were retrieved from hospital charts. 3. Results A total of 55 victims with OHCA were identified in 41 avalanche rescue missions and included in this retrospective study. Of the 55
avalanche victims 32 (58%) were declared dead at scene without any attempt at resuscitation. Of these 32 patients six were only partially buried and showed signs of severe trauma on external examination. The remaining 26 victims were completely buried and duration of snow burial exceeded 35 min in all 26 victims (median 155 min, range: 60 min to 14 days). In 23 (42%) of the 55 avalanche victims CPR was commenced at scene: in21 immediately after being extricated without signs of life and in 2 when witnessed cardiac arrest occurred after extrication. CPR was commenced in three partially buried victims, in nine completely buried victims with short duration of burial and in 11 completely buried victims with long duration of burial. 3.1. Outcome of partially buried victims None of the three partially buried victims survived to hospital discharge (patient characteristics, therapeutic interventions and outcome, see Table 1). Death was related to trauma in all three patients. One of the victims was already in cardiac arrest when the rescue team arrived. Two victims sustained witnessed cardiac arrest after rescue team arrival: one with severe accidental hypothermia developed ventricular fibrillation shortly after extrication (core temperature at scene was 20.5 ◦ C, at hospital admission 22 ◦ C) another victim with critical multisystem trauma sustained pulseless electrical activity during winch evacuation. 3.2. Outcome of completely buried victims with short duration of burial (less than 35 min) ROSC at scene was achieved in all nine patients. In four patients after bystander CPR before medical teams arrived at scene (all 4 extricated by comrade rescue within 20 min of burial) and in five patients after ALS administered by an emergency physician (4 of 5 were extricated by comrades within 20 min of burial and
Table 2 Patient characteristics and neurological outcome at hospital discharge of survivors (n = 5) with restoration of spontaneous circulation after short duration of burial (up to 35 min). Patient
Duration of burial (min)
ROSC after
GCS
SBP* (mmHg)
CT* (◦ C)
pH*
Lactate* (mmol L−1 )
Male, 49 years Male, 25 years
10 15
BLS BLS
14 3
150 80
35 31.5
7.29 7.31
4.1 8.8
Female, 30 years Male, 26 years Male, 31 years
15 20 20
BLS BLS ALS
3 4 4
110 140 100
30 28 24
7.12 7.02 6.85
12.0 11.9 19.9
Total body CT scan* Lung oedema Bilateral lung contusion, pneumothorax Normal Brain oedema Pulmonary infiltration, aspiration, brain oedema
ICU stay (days)
CPC
2 2
1 1
16 10 22
4 4 4
ROSC = restoration of spontaneous circulation, BLS = bystander CPR, ALS = advanced life support by emergency physician, GCS = best pre-hospital Glasgow Coma Score after ROSC, SBP = systolic blood pressure, CT = core body temperature, * at hospital admission, CPC = Cerebral Performance Category.
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Table 3 Patient characteristics of non-survivors (n = 4) with restoration of spontaneous circulation after short duration of burial (up to 35 min). Patient
Duration of burial (min)
ROSC after
GCS
SBP* (mmHg)
CT* (◦ C)
pH*
Lactate* (mmol L−1 )
Total body CT scan*
Outcome
Cause of death
Female, 41 years#
15
ALS
3
90
27
nd
nd
Died after 5 days
Brain injury
Male, 49 years# Male, 35 years
20 20
ALS ALS
nd 3
nd 80
nd 25
nd 6.84
nd 14.3
Died after 1 day Died after 9 days
Brain injury Brain injury
Male, 26 years
30
ALS
3
140
30
6.60
21.2
Brain oedema nd No pathological findings Brain oedema
Died after 7 days**
Brain death
# Transfer after initial treatment from tertiary hospital to Innsbruck University Hospital, SBP = systolic blood pressure, ALS = advanced life support by emergency physician, GCS = best pre-hospital Glasgow Coma Score after ROSC, CT = core body temperature, * at hospital admission, ** organ donation, nd = no data available.
received bystander CPR before medical personnel arrived at scene; one patient was extricated by the rescue team after 30 min of burial and resuscitated by an emergency physician). Five patients survived to hospital discharge (patient characteristics, see Table 2). All four patients with ROSC after bystander CPR survived to hospital discharge, two of them with full neurological recovery (cerebral performance category 1) and two with severe ischaemic brain injury (cerebral performance category 4). One patient with ROSC after ALS survived with severe ischaemic brain injury (cerebral performance category 4). Four patients died in hospital (patient characteristics, see Table 3); the cause of death in all 4 was irreversible ischaemic brain injury after asphyxia-related cardiac arrest. Core temperature on hospital admission was available for eight patients with short duration of burial: seven of eight had a core temperature below 32 ◦ C (Tables 2 and 3). Both patients surviving with good neurological outcome had pH values above 7.20 and a lactate concentration below 10 mmol L−1 . Patients dying from or surviving with severe ischaemic brain injury had a pH below 7.20 and lactate concentrations exceeding 10 mmol L−1 (Tables 2 and 3). Cerebral and pulmonary pathologies were the most common findings in whole body CT scans immediately after hospital admission in patients with ROSC at scene after short duration of burial (Tables 2 and 3). Cerebral oedema was present at hospital admission in four (67%) of six CT scans from patients dying from or surviving with severe ischaemic brain injury. 3.3. Outcome of completely buried victims with long duration of burial (longer than 35 min) In none of the 11 patients was spontaneous circulation able to be restored at scene. In five of them CPR was terminated at scene (mission characteristics, see Table 4). In the remaining six patients without ROSC at scene resuscitation efforts were continued until hospital admission (patient characteristics and treatment, see Table 5). All six patients with ongoing CPR had a core temperature lower than 32 ◦ C when admitted to hospital. All had pH values below 7.00 and serum lactate concentrations exceeding 10 mmol L−1 and one had a plasma potassium level exceeding 12 mmol L−1 . In three patients CPR was terminated after hospital
Table 4 Mission characteristics of avalanche victims (n = 5) with long duration of burial (more than 35 min) and termination of CPR at scene. Victim
ALS
Type of SAR
Reason for termination of CPR
Male, 38 years Male, 36 years Male, 55 years Male, 68 years Male, 51 years
No Yes Yes Yes Yes
Terrestrial Helicopter Helicopter Helicopter Terrestrial
Inability to evacuate patient under CPR Failed ALS Failed ALS Failed ALS Inability to evacuate patient under CPR
ALS = advanced life support by an emergency physician, SAR = search and rescue operation.
admission, three patients were supported and rewarmed using extracorporeal circulation. All three patients resuscitated with extracorporeal circulation died within 24 h while still on extracorporeal support (Table 5). Cause of death was irreversible hypoxic brain injury in all three patients Fig. 1.
4. Discussion Our data demonstrate a 91% overall mortality for avalanche victims with OHCA. Although prognosis is poor, survival with full neurological recovery was observed in two (22%) of nine victims with asphyxia-related OHCA following short duration of burial and ROSC already achieved at the site of the avalanche following immediate bystander CPR. Immediate cessation of respiration is typical for snow burial with obstructed airway.6,8 According to experimental data, cessation of respiration is followed by a drop in arterial oxygen saturation to 60% within 2 min and pulselessness occurs after 3–10 min.11 After 2 min of asphyxia-associated pulselessness irreversible ischaemic brain injury is expected.11 The brain is more susceptible to ischaemic injury during asphyxia than is the heart.11 These experiment findings may explain why a few avalanche victims with immediate bystander CPR after short burial times survive without subsequent neurological injury and ROSC is observed. Furthermore, hypercarbia is a major component of the pathophysiological processes during snow burial12,13 and hypoxia may be better tolerated if hypercarbia is a concomitant pathophysiological factor of asphyxiation.11 Our data indicate that within 20 min after burial there is a short period of time where bystander CPR can reverse asphyxia-associated cardiac arrest in avalanche victims without subsequent neurological injury. Similar experience has been reported in patients with asphyxia-associated cardiac arrest from hanging and non-fatal drowning, who were treated with therapeutic hypothermia.14,15 In our sample, ALS administered by an emergency physician did not improve outcome if bystander CPR did not previously restore spontaneous circulation, although ROSC has been observed in some victims after epinephrine administration. Current guidelines for the treatment of arrested avalanche victims focus on the need for prolonged CPR and extracorporeal support in avalanche victims with a patent airway and a duration of burial exceeding 35 min.4 In our sample we found no survivor after prolonged CPR or extracorporeal support. However, the number of patients studied in this case series is small and avalanche victims benefitting from extracorporeal support may not have been resuscitated until hospital admission. In fact, in 26 (57%) of 46 of our completely buried avalanche victims CPR was not initiated at scene despite the fact that duration of burial exceeded 35 min. It has been argued that noncompliance with current guidelines may harm potentially salvageable avalanche victims in cardiac arrest.16 On the other hand, the benefit of prolonged resuscitation and extracorporeal support for all avalanche victims with long duration of
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117
Table 5 Treatment and outcome of avalanche victims (n = 6) with long duration of burial (more than 35 min) admitted to hospital with ongoing CPR. Patient
Initial rhythm
CT (◦ C)
Duration of burial (min)
pH
Lactate (mmol L−1 )
Potassium (mmol L−1 )
Intervention
Remarks
Male, 60 years
AS
28
120
6.40
23.1
15.2
CPR stopped
Male, 56 years
PEA
28
40
6.57
18.1
4.3
ECMO
Male, 39 years
AS
27
40
6.58
21.4
4.9
ECMO
Male, 40 years
AS
26.5
40
6.52
26.8
6.6
ECMO
Male, 56 years
AS
26
60
6.70
nd
7.0
CPR stopped
Male, 35 years
AS
nd
80
nd
nd
nd
CPR stopped
Hyperkalaemia indicates irreversible asphyxia Died from irreversible brain injury within 24 h Died from irreversible brain injury within 24 h Died from irreversible brain injury within 24 h Irreversible asphyxia assumed Irreversible asphyxia assumed
AS = asystole, PEA = pulseless electrical activity, CT = core body temperature at hospital admission, ECMO = rewarming with extracorporeal membrane oxygenation. nd = no data available.
avalanche vicms with cardiac arrest n = 55 no CPR n = 32 CPR commenced at scene n = 23
paral burial n = 3
ROSC at scene n = 1 (CPR terminated n = 1)
burial < 35 min n = 9
ROSC at scene n = 9
burial > 35 min n = 11
ROSC at scene n = 0 (CPR terminated n = 5)
died in hospital n = 2
died in hospital n = 4
died in hospital n = 6
survived to discharge n = 0
survived to discharge n = 5*
survived to discharge n = 0
Fig. 1. Management and outcome of avalanche victims with out-of-hospital cardiac arrest (n = 55). Abbreviations: * two of five survived with full neurological recovery (cerebral performance category 1). ROSC = restoration of spontaneous circulation.
burial has been questioned in a recent study with a survival rate of only 7.1% in this subgroup.17 Another French study reported an overall survival rate of 16.7% in OHCA avalanche victims presenting with moderate or severe hypothermia, whereby only 6.3% showed favourable neurological outcome after 3 months.18 The number of arrested avalanche victims after long duration of burial benefitting from extracorporeal support is obviously small and the potential of extracorporeal support to improve survival in avalanche victims may be less than expected. One reason to withhold or terminate CPR is major trauma considered not compatible with survival. Mortality rates from severe trauma reported for avalanche victims in previous publications vary greatly, namely between 5% and 24%, depending on mountain topography and type of recreational activity.10,19 Six of 32 victims were declared dead on external examination at the site of the avalanche due to severe trauma and three others died from trauma after hospital admission. The 16% incidence of fatal trauma observed in this study is higher than the incidence of fatal trauma previously reported for the European Alps.19 The higher trauma rate may reflect a trend towards skiing more exposed and steep terrain in the Alps over recent years, although six cases were declared dead solely upon external medical examination on scene. Almost all avalanche victims with ROSC at scene were hypothermic on admission to hospital and most of them had a core
temperature below 30 ◦ C. Considering the short duration of burial, hypothermia must have developed after extrication during medical treatment and transportation. Mild hypothermia induced early after cardiac arrest improves neurological outcome, although the core temperature necessary to achieve a protective effect is controversial.20 A reduction in core temperature below 32 ◦ C may be associated with higher rates of morbidity and mortality.21 The particular circumstances of an avalanche rescue operation can induce even severe hypothermia very rapidly after extrication, as shown in this study. Therefore, efficient insulation, application of heat packs and core temperature monitoring are of great importance in avoiding a critical reduction in body core temperature below 30 ◦ C. The major reason for morbidity and mortality in our study population was severe ischaemic brain injury. In more than half of all avalanche victims with ROSC severe cerebral injury was already indicated by significant cerebral oedema seen in a CT scan at hospital admission. Cerebral oedema is a known poor prognostic sign for patients resuscitated after asphyxia,15 and a CT scan on hospital arrival may be helpful in identifying avalanche victims with a particularly dismal prognosis very early. CT scan indicating lung contusion or aspiration was another pathology observed in our study population. Lung oedema with acute respiratory failure was observed in one patient with a history
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of a few minutes complete burial with obstructed airway. Acute respiratory failure due to lung oedema has been described previously for completely buried avalanche victims.22–25 Pulmonary hypertension, acute left heart failure, chest compression and negative intra-alveolar pressure have all been suggested as possible underlying mechanisms.24,25 Lung oedema associated with snow burial is reversible within hours in most patients.24,25 In our data survival was the consequence of immediate bystander CPR after a few minutes of burial. Thus, search techniques, rapid extrication and bystander CPR must be part of the skills taught to all persons who are exposed to avalanche risk. Due to the underlying pathophysiology of cardiac arrest in avalanche accidents, ventilation techniques should be an essential part of CPR training for this particular group of first responders.26
5. 6. 7. 8. 9. 10. 11.
12.
5. Conclusions Although overall prognosis is poor in avalanche victims with OHCA, survival is possible in victims with asphyxia-related cardiac arrest with short duration of burial times if bystander CPR is immediately performed and ROSC achieved. Strategies for improving survival in avalanche victims should focus on reducing burial duration by teaching immediate rescue to be performed by uninjured companions and by improving skiers’ and snowboarders’ knowledge and skills in bystander CPR. Full body thermal insulation is important to avoid critical hypothermia in all avalanche victims with ROSC at the site of the avalanche.
13.
14.
15.
16.
17.
18.
Conflict of interest statement
19.
None of the authors has any financial or personal relationship that could have inappropriately influenced the work.
20.
21.
References 1. Boyd J, Brugger H, Shuster M. Prognostic factors in avalanche resuscitation: a systematic review. Resuscitation 2010;81:845–52. 2. Althaus U, Aeberhard P, Schuepbach P, Nachbaur B, Muehlemann W. Management of profound accidental hypothermia with cardiorespiratory arrest. Ann Surg 1982;195:492–5. 3. Oberhammer R, Beikircher W, Hoermann C, et al. Full recovery of an avalanche victim with profound hypothermia and prolonged cardiac arrest treated by extracorporeal re-warming. Resuscitation 2008;76:474–80. 4. Brugger H, Durrer B, Elsensohn F, et al. Resuscitation of avalanche victims: evidence-based guidelines of the International Commission for Mountain
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Emergency Medicine (ICAR MEDCOM): intended for physicians and other advanced life support personnel. Resuscitation 2013;84:539–46. Haegeli P, Falk M, Brugger H, Etter HJ, Boyd J. Comparison of avalanche survival patterns in Canada and Switzerland. CMAJ 2011;183:789–95. Brugger H, Paal P, Boyd J. Prehospital resuscitation of the buried avalanche victim. High Alt Med Biol 2011;12:199–205. McIntosh SE, Grissom CK, Olivares CR, Kim HS, Tremper B. Cause of death in avalanche victims. Wilderness Environ Med 2007;18:293–7. Falk M, Brugger H, Adler-Kastner L. Avalanche survival chances. Nature 1994;368:21. Mair P, Frimmel C, Vergeiner G, et al. Emergency medical helicopter operations for avalanche accidents. Resuscitation 2013;84:492–5. Boyd J, Haegeli P, Abu-Laban RB, Shuster M, Butt JC. Patterns of death among avalanche fatalities: a 21-year review. CMAJ 2009;180:507–12. Safar P, Paradis NA, Weil MH. Asphyxial cardiac arrest. In: Paradis NA, Halperin HR, Kern KB, Wenzel V, Chamberlain DA, editors. Cardiac arrest – the science and practice of resuscitation medicine. Cambridge: Cambridge University Press; 2007. p. 969–93. Grissom CK, Radwin M, Harmston C. Respiration during snow burial using an artificial air pocket. JAMA 2000;283:2266–71. 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;58:81–8. Legriel S, Bouyon A, Nekhili N, et al. Therapeutic hypothermia for coma after cardiorespiratory arrest caused by hanging. Resuscitation 2005;67: 143–4. Baldursdotir S, Sigvaldason K, Karason S, Valsson F, Sigurdsson GH. Induced hypothermia in comatose survivors of asphyxia: a case series of 14 consecutive cases. Acta Anaesthesiol Scand 2010;54:821–6. Strapazzon G, Beikircher W, Procter E, Brugger H. Electrical heart activity recorded during prolonged avalanche burial. Circulation 2012;125: 646–7. Mair P, Brugger H, Mair B, Moroder L, Ruttmann E. Is extracorporeal rewarming indicated in avalanche victims with unwitnessed hypothermic cardiorespiratory arrest? High Alt Med Biol 2014;15:500–3. Boue Y, Payer JF, Brun J, et al. Survival after avalanche-induced cardiac arrest. Resuscitation 2014;85:1192–6. Hohlrieder M, Brugger H, Schubert H. Pattern and severity of injury in avalanche victims. High Alt Med Biol 2007;8:56–61. Wise MP, Horn J, Aneman A, Nilsen N. Targeted temperature management after out-of-hospital cardiac arrest: certainties and uncertainties. Crit Care 2014;18:459–61. Brown DJA, Brugger H, Boyd J, Paal P. Accidental hypothermia. N Engl J Med 2012;367:1930–8. Wick MC, Weiss RJ, Hohlrieder M, Tecklenburg K, Jaschke W, Rieger M. Radiological aspects of injuries of avalanche victims. Injury 2009;40:93–8. Grosse AB, Grosse CA, Steinbach LS, Zimmermann H, Anderson S. Imaging findings of avalanche victims. Skeletal Radiol 2007;36:515–21. Sumann G, Putzer G, Brugger H, Paal P. Pulmonary edema after complete avalanche burial. High Alt Med Biol 2012;13:295–6. Schmid F. The pathogenesis of pulmonary edema after being buried by an avalanche. Schweiz Med Wochenschr 1981;26:1441–5. Wolcke B. Lay-rescuer CPR – controversies in emergency medicine: lay rescuer CPR with or without mouth-to-mouth ventilation. Anasthesiol Intensivmed Notfallmed Schmerzther 2013;48:558–61.
Contents lists available at ScienceDirect
Resuscitation journal homepage: www.elsevier.com/locate/resuscitation
Clinical Paper
Outcome of avalanche victims with out-of-hospital cardiac arrest夽 Luca Moroder a , Birgit Mair a,b , Hermann Brugger c , Wolfgang Voelckel b,d , Peter Mair a,b,∗ a
Department of Anaesthesiology and Critical Care Medicine, Medical University of Innsbruck, Anichstrasse 35, 6020 Innsbruck, Austria Christophorus Emergency Medical Helicopter Service, Schubertring 1-3, 1010 Vienna, Austria c Institute of Mountain Emergency Medicine, EURAC Research, Viale Druso 1, 39100 Bolzano, Italy d Department of Anesthesiology and Critical Care Medicine, AUVA Trauma Hospital Salzburg, Dr.-Franz-Rehrl-Platz 4, 5010 Salzburg, Austria b
a r t i c l e
i n f o
Article history: Received 28 November 2014 Received in revised form 13 January 2015 Accepted 16 January 2015 Keywords: Cardiopulmonary resuscitation Avalanche Asphyxia Outcome Bystander
a b s t r a c t Study background: Previous studies focused on the outcome of avalanche victims with out-of-hospital cardiac arrest (OHCA) after long duration of burial (>35 min); the outcome of victims with short duration (≤35 min) remains obscure. Aim of the study: To investigate outcome of avalanche victims with OHCA. Methods: Retrospective analysis of avalanche victims with OHCA between 2008 and 2013 in the Tyrolean Alps. Results: 55 avalanche victims were identified, 32 of whom were declared dead after extrication without cardiopulmonary resuscitation (CPR), all with long duration of burial. In the remaining 23 CPR was initiated at scene; three were partially and 20 completely buried, nine of whom suffered short and 11 long duration of burial. All nine victims with short duration of burial underwent restoration of spontaneous circulation (ROSC) at scene, four of them after bystander CPR, five after advanced life support by the emergency physician. Two patients with ROSC after short duration of burial and bystander CPR survived to hospital discharge with cerebral performance category 1. None of the 11 victims with long duration of burial survived to hospital discharge, although six were transported to hospital with ongoing CPR and three were supported with extracorporeal circulation. Conclusions: In this case series survival with favourable neurological outcome was observed in avalanche victims with short duration of burial only if bystander CPR was immediately performed and ROSC achieved. Strategies for reducing avalanche mortality should focus on prompt extrication from the snow and immediate bystander CPR by uninjured companions. © 2015 Elsevier Ireland Ltd. All rights reserved.
1. Introduction Several publications have highlighted the possibility of survival in avalanche victims with long duration of complete burial and outof-hospital cardiac arrest (OHCA) due to the protective effects of accidental hypothermia that can develop after more than 35 min snow burial.1–3 Recommendations for the triage and management of arrested avalanche victims with duration of burial exceeding 35 min have been published.4 Asphyxia, however, is considered the main underlying pathology for cardiac arrest, while hypothermia is a rare reason for cardiac arrest in avalanche accidents.5–7 With the use of avalanche transceivers many completely buried
夽 A Spanish translated version of the abstract of this article appears as Appendix in the final online version at http://dx.doi.org/10.1016/j.resuscitation.2015.01.019. ∗ Corresponding author at: Department of Anaesthesiology and Critical Care Medicine, Medical University of Innsbruck, Anichstrasse 35, 6020 Innsbruck, Austria. E-mail address: [email protected] (P. Mair). http://dx.doi.org/10.1016/j.resuscitation.2015.01.019 0300-9572/© 2015 Elsevier Ireland Ltd. All rights reserved.
victims can be extricated from the snow within less than 35 min and resuscitated by bystanders, if necessary.6,8,9 The outcome of patients presenting with OHCA after short duration of burial (up to 35 min) has not yet been studied. In such cases asphyxia or trauma, but not hypothermia, may be the cause of cardiac arrest.5,6,9,10 The current study evaluated the pre-hospital and in-hospital resuscitation measures and outcome of patients with OHCA in a consecutive series of avalanche victims.
2. Methods After Ethics Committee approval all rescue missions conducted for avalanche accidents in the Austrian state of Tyrol during five consecutive winter seasons (October 2008 to June 2013) were reviewed. Rescue missions involving at least one victim with OHCA were identified and included in this retrospective observational study.
L. Moroder et al. / Resuscitation 89 (2015) 114–118
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Table 1 Patient characteristics and outcome of partially buried avalanche victims (n = 3) with out-of-hospital cardiac arrest. CT* (◦ C)
pH*
Lactate* (mmol L−1 )
Potassium* (mmol L−1 )
Outcome
Cause of death
Remarks
–
Died on scene Died after 2 days
Multisystem trauma Brain injury, spinal shock Intractable bleeding
ALS stopped on scene Spine fracture C1 /C2 , spinal cord lesion, brain oedema Multisystem trauma, rewarming with ECMO
Patient
Rhythm
Male, 38 years#
PEA
–
Male, 33 years
PEA
30
7.00
12.4
3.6
Male, 49 years#
VF
22
6.95
10.0
3.8
–
–
Died after 5h
# Witnessed cardiac arrest, PEA = pulseless electrical activity, VF = ventricular fibrillation, CT = core body temperature, * at hospital admission, ALS = advanced life support by emergency physician, ECMO = extracorporeal membrane oxygenation.
Data on accident and rescue mission characteristics were retrieved from accident reports of the Tyrolean Avalanche Forecast Centre and from mission protocols of the rescue services involved. Data included date and location of the avalanche accident, burial status of the victims (partially buried, completely buried), type of rescue for completely buried victims (bystander rescue or rescue by the organized rescue team) and duration of burial. A victim was considered partially buried when his head was unburied and the victim was able to breath. A victim was considered completely buried when his head was under the snow and he was at risk of suffocating. Duration of burial is considered short for durations up to 35 min and long if duration exceeds 35 min. Medical parts of the mission protocols were reviewed by two of the authors (L.M., P.M.) to retrieve available information concerning the victim’s medical condition and pre-hospital therapy. Pre-hospital data included circumstances of cardiac arrest (witnessed, unwitnessed), type of CPR (no CPR, bystander CPR, advanced life support [ALS] by an emergency physician) and outcome of pre-hospital CPR efforts (terminated at scene, ongoing CPR until hospital admission, ROSC after bystander CPR or ROSC after ALS by an emergency physician). In-hospital data included termination of CPR, duration of intensive care unit stay, transfer from outside hospital to Innsbruck Medical University Hospital and survival and neurological outcome using the Cerebral Performance Category Scale. In addition, for all patients admitted to Innsbruck Medical University systolic blood pressure, core temperature, pH (not temperature corrected), serum potassium and serum lactate concentrations and whole body computed tomography (CT) scan findings on admission were retrieved from hospital charts. 3. Results A total of 55 victims with OHCA were identified in 41 avalanche rescue missions and included in this retrospective study. Of the 55
avalanche victims 32 (58%) were declared dead at scene without any attempt at resuscitation. Of these 32 patients six were only partially buried and showed signs of severe trauma on external examination. The remaining 26 victims were completely buried and duration of snow burial exceeded 35 min in all 26 victims (median 155 min, range: 60 min to 14 days). In 23 (42%) of the 55 avalanche victims CPR was commenced at scene: in21 immediately after being extricated without signs of life and in 2 when witnessed cardiac arrest occurred after extrication. CPR was commenced in three partially buried victims, in nine completely buried victims with short duration of burial and in 11 completely buried victims with long duration of burial. 3.1. Outcome of partially buried victims None of the three partially buried victims survived to hospital discharge (patient characteristics, therapeutic interventions and outcome, see Table 1). Death was related to trauma in all three patients. One of the victims was already in cardiac arrest when the rescue team arrived. Two victims sustained witnessed cardiac arrest after rescue team arrival: one with severe accidental hypothermia developed ventricular fibrillation shortly after extrication (core temperature at scene was 20.5 ◦ C, at hospital admission 22 ◦ C) another victim with critical multisystem trauma sustained pulseless electrical activity during winch evacuation. 3.2. Outcome of completely buried victims with short duration of burial (less than 35 min) ROSC at scene was achieved in all nine patients. In four patients after bystander CPR before medical teams arrived at scene (all 4 extricated by comrade rescue within 20 min of burial) and in five patients after ALS administered by an emergency physician (4 of 5 were extricated by comrades within 20 min of burial and
Table 2 Patient characteristics and neurological outcome at hospital discharge of survivors (n = 5) with restoration of spontaneous circulation after short duration of burial (up to 35 min). Patient
Duration of burial (min)
ROSC after
GCS
SBP* (mmHg)
CT* (◦ C)
pH*
Lactate* (mmol L−1 )
Male, 49 years Male, 25 years
10 15
BLS BLS
14 3
150 80
35 31.5
7.29 7.31
4.1 8.8
Female, 30 years Male, 26 years Male, 31 years
15 20 20
BLS BLS ALS
3 4 4
110 140 100
30 28 24
7.12 7.02 6.85
12.0 11.9 19.9
Total body CT scan* Lung oedema Bilateral lung contusion, pneumothorax Normal Brain oedema Pulmonary infiltration, aspiration, brain oedema
ICU stay (days)
CPC
2 2
1 1
16 10 22
4 4 4
ROSC = restoration of spontaneous circulation, BLS = bystander CPR, ALS = advanced life support by emergency physician, GCS = best pre-hospital Glasgow Coma Score after ROSC, SBP = systolic blood pressure, CT = core body temperature, * at hospital admission, CPC = Cerebral Performance Category.
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Table 3 Patient characteristics of non-survivors (n = 4) with restoration of spontaneous circulation after short duration of burial (up to 35 min). Patient
Duration of burial (min)
ROSC after
GCS
SBP* (mmHg)
CT* (◦ C)
pH*
Lactate* (mmol L−1 )
Total body CT scan*
Outcome
Cause of death
Female, 41 years#
15
ALS
3
90
27
nd
nd
Died after 5 days
Brain injury
Male, 49 years# Male, 35 years
20 20
ALS ALS
nd 3
nd 80
nd 25
nd 6.84
nd 14.3
Died after 1 day Died after 9 days
Brain injury Brain injury
Male, 26 years
30
ALS
3
140
30
6.60
21.2
Brain oedema nd No pathological findings Brain oedema
Died after 7 days**
Brain death
# Transfer after initial treatment from tertiary hospital to Innsbruck University Hospital, SBP = systolic blood pressure, ALS = advanced life support by emergency physician, GCS = best pre-hospital Glasgow Coma Score after ROSC, CT = core body temperature, * at hospital admission, ** organ donation, nd = no data available.
received bystander CPR before medical personnel arrived at scene; one patient was extricated by the rescue team after 30 min of burial and resuscitated by an emergency physician). Five patients survived to hospital discharge (patient characteristics, see Table 2). All four patients with ROSC after bystander CPR survived to hospital discharge, two of them with full neurological recovery (cerebral performance category 1) and two with severe ischaemic brain injury (cerebral performance category 4). One patient with ROSC after ALS survived with severe ischaemic brain injury (cerebral performance category 4). Four patients died in hospital (patient characteristics, see Table 3); the cause of death in all 4 was irreversible ischaemic brain injury after asphyxia-related cardiac arrest. Core temperature on hospital admission was available for eight patients with short duration of burial: seven of eight had a core temperature below 32 ◦ C (Tables 2 and 3). Both patients surviving with good neurological outcome had pH values above 7.20 and a lactate concentration below 10 mmol L−1 . Patients dying from or surviving with severe ischaemic brain injury had a pH below 7.20 and lactate concentrations exceeding 10 mmol L−1 (Tables 2 and 3). Cerebral and pulmonary pathologies were the most common findings in whole body CT scans immediately after hospital admission in patients with ROSC at scene after short duration of burial (Tables 2 and 3). Cerebral oedema was present at hospital admission in four (67%) of six CT scans from patients dying from or surviving with severe ischaemic brain injury. 3.3. Outcome of completely buried victims with long duration of burial (longer than 35 min) In none of the 11 patients was spontaneous circulation able to be restored at scene. In five of them CPR was terminated at scene (mission characteristics, see Table 4). In the remaining six patients without ROSC at scene resuscitation efforts were continued until hospital admission (patient characteristics and treatment, see Table 5). All six patients with ongoing CPR had a core temperature lower than 32 ◦ C when admitted to hospital. All had pH values below 7.00 and serum lactate concentrations exceeding 10 mmol L−1 and one had a plasma potassium level exceeding 12 mmol L−1 . In three patients CPR was terminated after hospital
Table 4 Mission characteristics of avalanche victims (n = 5) with long duration of burial (more than 35 min) and termination of CPR at scene. Victim
ALS
Type of SAR
Reason for termination of CPR
Male, 38 years Male, 36 years Male, 55 years Male, 68 years Male, 51 years
No Yes Yes Yes Yes
Terrestrial Helicopter Helicopter Helicopter Terrestrial
Inability to evacuate patient under CPR Failed ALS Failed ALS Failed ALS Inability to evacuate patient under CPR
ALS = advanced life support by an emergency physician, SAR = search and rescue operation.
admission, three patients were supported and rewarmed using extracorporeal circulation. All three patients resuscitated with extracorporeal circulation died within 24 h while still on extracorporeal support (Table 5). Cause of death was irreversible hypoxic brain injury in all three patients Fig. 1.
4. Discussion Our data demonstrate a 91% overall mortality for avalanche victims with OHCA. Although prognosis is poor, survival with full neurological recovery was observed in two (22%) of nine victims with asphyxia-related OHCA following short duration of burial and ROSC already achieved at the site of the avalanche following immediate bystander CPR. Immediate cessation of respiration is typical for snow burial with obstructed airway.6,8 According to experimental data, cessation of respiration is followed by a drop in arterial oxygen saturation to 60% within 2 min and pulselessness occurs after 3–10 min.11 After 2 min of asphyxia-associated pulselessness irreversible ischaemic brain injury is expected.11 The brain is more susceptible to ischaemic injury during asphyxia than is the heart.11 These experiment findings may explain why a few avalanche victims with immediate bystander CPR after short burial times survive without subsequent neurological injury and ROSC is observed. Furthermore, hypercarbia is a major component of the pathophysiological processes during snow burial12,13 and hypoxia may be better tolerated if hypercarbia is a concomitant pathophysiological factor of asphyxiation.11 Our data indicate that within 20 min after burial there is a short period of time where bystander CPR can reverse asphyxia-associated cardiac arrest in avalanche victims without subsequent neurological injury. Similar experience has been reported in patients with asphyxia-associated cardiac arrest from hanging and non-fatal drowning, who were treated with therapeutic hypothermia.14,15 In our sample, ALS administered by an emergency physician did not improve outcome if bystander CPR did not previously restore spontaneous circulation, although ROSC has been observed in some victims after epinephrine administration. Current guidelines for the treatment of arrested avalanche victims focus on the need for prolonged CPR and extracorporeal support in avalanche victims with a patent airway and a duration of burial exceeding 35 min.4 In our sample we found no survivor after prolonged CPR or extracorporeal support. However, the number of patients studied in this case series is small and avalanche victims benefitting from extracorporeal support may not have been resuscitated until hospital admission. In fact, in 26 (57%) of 46 of our completely buried avalanche victims CPR was not initiated at scene despite the fact that duration of burial exceeded 35 min. It has been argued that noncompliance with current guidelines may harm potentially salvageable avalanche victims in cardiac arrest.16 On the other hand, the benefit of prolonged resuscitation and extracorporeal support for all avalanche victims with long duration of
L. Moroder et al. / Resuscitation 89 (2015) 114–118
117
Table 5 Treatment and outcome of avalanche victims (n = 6) with long duration of burial (more than 35 min) admitted to hospital with ongoing CPR. Patient
Initial rhythm
CT (◦ C)
Duration of burial (min)
pH
Lactate (mmol L−1 )
Potassium (mmol L−1 )
Intervention
Remarks
Male, 60 years
AS
28
120
6.40
23.1
15.2
CPR stopped
Male, 56 years
PEA
28
40
6.57
18.1
4.3
ECMO
Male, 39 years
AS
27
40
6.58
21.4
4.9
ECMO
Male, 40 years
AS
26.5
40
6.52
26.8
6.6
ECMO
Male, 56 years
AS
26
60
6.70
nd
7.0
CPR stopped
Male, 35 years
AS
nd
80
nd
nd
nd
CPR stopped
Hyperkalaemia indicates irreversible asphyxia Died from irreversible brain injury within 24 h Died from irreversible brain injury within 24 h Died from irreversible brain injury within 24 h Irreversible asphyxia assumed Irreversible asphyxia assumed
AS = asystole, PEA = pulseless electrical activity, CT = core body temperature at hospital admission, ECMO = rewarming with extracorporeal membrane oxygenation. nd = no data available.
avalanche vicms with cardiac arrest n = 55 no CPR n = 32 CPR commenced at scene n = 23
paral burial n = 3
ROSC at scene n = 1 (CPR terminated n = 1)
burial < 35 min n = 9
ROSC at scene n = 9
burial > 35 min n = 11
ROSC at scene n = 0 (CPR terminated n = 5)
died in hospital n = 2
died in hospital n = 4
died in hospital n = 6
survived to discharge n = 0
survived to discharge n = 5*
survived to discharge n = 0
Fig. 1. Management and outcome of avalanche victims with out-of-hospital cardiac arrest (n = 55). Abbreviations: * two of five survived with full neurological recovery (cerebral performance category 1). ROSC = restoration of spontaneous circulation.
burial has been questioned in a recent study with a survival rate of only 7.1% in this subgroup.17 Another French study reported an overall survival rate of 16.7% in OHCA avalanche victims presenting with moderate or severe hypothermia, whereby only 6.3% showed favourable neurological outcome after 3 months.18 The number of arrested avalanche victims after long duration of burial benefitting from extracorporeal support is obviously small and the potential of extracorporeal support to improve survival in avalanche victims may be less than expected. One reason to withhold or terminate CPR is major trauma considered not compatible with survival. Mortality rates from severe trauma reported for avalanche victims in previous publications vary greatly, namely between 5% and 24%, depending on mountain topography and type of recreational activity.10,19 Six of 32 victims were declared dead on external examination at the site of the avalanche due to severe trauma and three others died from trauma after hospital admission. The 16% incidence of fatal trauma observed in this study is higher than the incidence of fatal trauma previously reported for the European Alps.19 The higher trauma rate may reflect a trend towards skiing more exposed and steep terrain in the Alps over recent years, although six cases were declared dead solely upon external medical examination on scene. Almost all avalanche victims with ROSC at scene were hypothermic on admission to hospital and most of them had a core
temperature below 30 ◦ C. Considering the short duration of burial, hypothermia must have developed after extrication during medical treatment and transportation. Mild hypothermia induced early after cardiac arrest improves neurological outcome, although the core temperature necessary to achieve a protective effect is controversial.20 A reduction in core temperature below 32 ◦ C may be associated with higher rates of morbidity and mortality.21 The particular circumstances of an avalanche rescue operation can induce even severe hypothermia very rapidly after extrication, as shown in this study. Therefore, efficient insulation, application of heat packs and core temperature monitoring are of great importance in avoiding a critical reduction in body core temperature below 30 ◦ C. The major reason for morbidity and mortality in our study population was severe ischaemic brain injury. In more than half of all avalanche victims with ROSC severe cerebral injury was already indicated by significant cerebral oedema seen in a CT scan at hospital admission. Cerebral oedema is a known poor prognostic sign for patients resuscitated after asphyxia,15 and a CT scan on hospital arrival may be helpful in identifying avalanche victims with a particularly dismal prognosis very early. CT scan indicating lung contusion or aspiration was another pathology observed in our study population. Lung oedema with acute respiratory failure was observed in one patient with a history
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of a few minutes complete burial with obstructed airway. Acute respiratory failure due to lung oedema has been described previously for completely buried avalanche victims.22–25 Pulmonary hypertension, acute left heart failure, chest compression and negative intra-alveolar pressure have all been suggested as possible underlying mechanisms.24,25 Lung oedema associated with snow burial is reversible within hours in most patients.24,25 In our data survival was the consequence of immediate bystander CPR after a few minutes of burial. Thus, search techniques, rapid extrication and bystander CPR must be part of the skills taught to all persons who are exposed to avalanche risk. Due to the underlying pathophysiology of cardiac arrest in avalanche accidents, ventilation techniques should be an essential part of CPR training for this particular group of first responders.26
5. 6. 7. 8. 9. 10. 11.
12.
5. Conclusions Although overall prognosis is poor in avalanche victims with OHCA, survival is possible in victims with asphyxia-related cardiac arrest with short duration of burial times if bystander CPR is immediately performed and ROSC achieved. Strategies for improving survival in avalanche victims should focus on reducing burial duration by teaching immediate rescue to be performed by uninjured companions and by improving skiers’ and snowboarders’ knowledge and skills in bystander CPR. Full body thermal insulation is important to avoid critical hypothermia in all avalanche victims with ROSC at the site of the avalanche.
13.
14.
15.
16.
17.
18.
Conflict of interest statement
19.
None of the authors has any financial or personal relationship that could have inappropriately influenced the work.
20.
21.
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