Outcomes of patients suffering unwitnessed hypothermic cardiac arrest rewarmed with extracorporeal life support: A systematic review.

Prolonged cardiac arrest (CA) may lead to neurologic deficit in survivors. Good outcome is especially rare when CA was unwitnessed. However, accidental hypothermia is a very specific cause of CA. Our goal was to describe the outcomes of patients who suffered from unwitnessed hypothermic cardiac arrest (UHCA) supported with Extracorporeal Life Support (ECLS). We included consecutive patients' cohorts identified by systematic literature review concerning patients suffering from UHCA and rewarmed with ECLS. Patients were divided into four subgroups regarding the mechanism of cooling, namely: air exposure; immersion; submersion; and avalanche. A statistical analysis was performed in order to identify the clinical parameters associated with good outcome (survival and absence of neurologic impairment). A total of 221 patients were included into the study. The overall survival rate was 27%. Most of the survivors (83%), had no neurologic deficit. Asystole was the presenting CA rhythm in 48% survivors, of which 79% survived with good neurologic outcome. Variables associated with survival included the following: female gender (P < .001); low core temperature (P = .005); non-asphyxia-related mechanism of cooling (P < .001); pulseless electrical activity as an initial rhythm (P < .001); high blood pH (P < .001); low lactate levels (P = .003); low serum potassium concentration (P < .001); and short resuscitation duration (P = .004). Severely hypothermic patients with unwitnessed CA may survive with good neurologic outcome, including those presenting as asystole. The initial blood pH, potassium, and lactate concentration may help predict outcome in hypothermic CA.

Intranasal sufentanil versus intravenous morphine for acute severe trauma pain: A double-blind randomized non-inferiority study.

BACKGROUND: Intravenous morphine (IVM) is the most common strong analgesic used in trauma, but is associated with a clear time limitation related to the need to obtain an access route. The intranasal (IN) route provides easy administration with a fast peak action time due to high vascularization and the absence of first-pass metabolism. We aimed to determine whether IN sufentanil (INS) for patients presenting to an emergency department with acute severe traumatic pain results in a reduction in pain intensity non-inferior to IVM. METHODS AND FINDINGS: In a prospective, randomized, multicenter non-inferiority trial conducted in the emergency departments of 6 hospitals across France, patients were randomized 1:1 to INS titration (0.3 µg/kg and additional doses of 0.15 µg/kg at 10 minutes and 20 minutes if numerical pain rating scale [NRS] > 3) and intravenous placebo, or to IVM (0.1 mg/kg and additional doses of 0.05 mg/kg at 10 minutes and 20 minutes if NRS > 3) and IN placebo. Patients, clinical staff, and research staff were blinded to the treatment allocation. The primary endpoint was the total decrease on NRS at 30 minutes after first administration. The prespecified non-inferiority margin was -1.3 on the NRS. The primary outcome was analyzed per protocol. Adverse events were prospectively recorded during 4 hours. Among the 194 patients enrolled in the emergency department cohort between November 4, 2013, and April 10, 2016, 157 were randomized, and the protocol was correctly administered in 136 (69 IVM group, 67 INS group, per protocol population, 76% men, median age 40 [IQR 29 to 54] years). The mean difference between NRS at first administration and NRS at 30 minutes was -4.1 (97.5% CI -4.6 to -3.6) in the IVM group and -5.2 (97.5% CI -5.7 to -4.6) in the INS group. Non-inferiority was demonstrated (p < 0.001 with 1-sided mean-equivalence t test), as the lower 97.5% confidence interval of 0.29 (97.5% CI 0.29 to 1.93) was above the prespecified margin of -1.3. INS was superior to IVM (intention to treat analysis: p = 0.034), but without a clinically significant difference in mean NRS between groups. Six severe adverse events were observed in the INS group and 2 in the IVM group (number needed to harm: 17), including an apparent imbalance for hypoxemia (3 in the INS group versus 1 in the IVM group) and for bradypnea (2 in the INS group versus 0 in the IVM group). The main limitation of the study was that the choice of concomitant analgesics, when they were used, was left to the discretion of the physician in charge, and co-analgesia was more often used in the IVM group. Moreover, the size of the study did not allow us to conclude with certainty about the safety of INS in emergency settings. CONCLUSIONS: We confirm the non-inferiority of INS compared to IVM for pain reduction at 30 minutes after administration in patients with severe traumatic pain presenting to an emergency department. The IN route, with no need to obtain a venous route, may allow early and effective analgesia in emergency settings and in difficult situations. Confirmation of the safety profile of INS will require further larger studies. TRIAL REGISTRATION: ClinicalTrials.gov NCT02095366. EudraCT 2013-001665-16.

Serum potassium concentration predicts brain hypoxia on CT after avalanche-induced cardiac arrest.

BACKGROUND: Brain anoxia after complete avalanche burial and cardiac arrest (CA) may occur despite adequate on-site triage. PURPOSE: To investigate clinical and biological parameters associated with brain hypoxia in a cohort of avalanche victims with whole body computed tomographic (CT) scan. METHODS: Retrospective study of patients with CA and whole body CT scan following complete avalanche burial admitted in a level-I trauma center. MAIN FINDINGS: Out of 19 buried patients with whole body CT scan, eight patients had refractory CA and 11 patients had pre-hospital return of spontaneous circulation. Six patients survived at hospital discharge and only two had good neurologic outcome. Twelve patients had signs of brain hypoxia on initial CT scan, defined as brain edema, loss of gray/white matter differentiation and/or hypodensity of basal ganglia. No clinical pre-hospital parameter was associated with brain anoxia. Serum potassium concentration at admission was higher in patients with brain anoxia as compared to patients with normal CT scan: 5.5 (4.1-7.2) mmol/L versus 3.3 (3.0-4.2) mmol/L, respectively (P<.01). A threshold of 4.35 mmol/L serum potassium had 100% specificity to predict brain anoxia on brain CT scan. CONCLUSIONS: Serum potassium concentration had good predictive value for brain anoxia after complete avalanche burial. This finding further supports the use of serum potassium concentration for extracorporeal life support insertion at hospital admission in this context.

Medical Pathologies and Hut Guardians' Ability to Provide First Aid in Mountain Huts: A Prospective Observational Study.

OBJECTIVE: To describe the resources for medical condition management in mountain huts and the epidemiology of such events. METHODS: We conducted a 3-step study from April 2013 to August 2014 in French mountain huts. The first step consisted of collecting data regarding the first aid equipment available in mountain huts. The second step consisted of a qualitative evaluation of the mountain hut guardian's role in medical situations through semistructured interviews. Finally, a prospective observational study was conducted in the summer season to collect all medical events (MEs) that occurred during that period. RESULTS: Out of 164 hut guardians, 141 (86%) had a basic life support diploma. An automatic external defibrillator was available in 41 (26%) huts, and 148 huts (98%) were equipped with a first aid kit. According to semistructured interviews, hut guardians played a valuable role in first aid assistance. Regarding the observational study, 306 people requested the hut guardian's help for medical reasons in 87 of the 126 huts included. A total of 501 MEs for approximately 56,000 hikers (0.85%) were reported, with 280 MEs (56%) involving medical pathologies and 221 (44%) MEs involving trauma-related injuries. CONCLUSIONS: MEs had low prevalence, but the hut guardian played a valuable role as a first aid responder.

Survivors of avalanche accidents: posttraumatic stress disorder symptoms and quality of life: a multicentre study.

BACKGROUND: As any traumatic event, avalanches could trigger psychological disorders on survivors. Our objectives were to determine the prevalence of post-traumatic stress disorder among avalanche survivors and to evaluate post-traumatic stress disorder risks factors as well as the impact on quality of life. METHODS: A multicentre study was conducted in victims included in the North Alpine Avalanche Registry from 2014 to 2018. Data were collected through a standard questionnaire during semi-directed phone interviews. The primary outcome was the total score on the Impact of Event Scale Revised. Secondary outcomes were the Mental Component Scale and the Physical Component Scale scores of the Short Form 12 questionnaire. RESULTS: During the study period, 132 of 211 victims survived. Among the 107 victims included, 55 (51.4%) phone interviews were obtained. Six patients (10.9, 95% CI 1.76-20.05) had an Impact of Event Scale Revised score ≥ 33 indicating a strong probability for post-traumatic stress disorder. Median Mental Component Scale score was 39.0 (IQR 30.5-46.3) for post-traumatic stress disorder patients and 40.1 (IQR 36.5-43.4) for non post-traumatic stress disorder (p = 0.76). Median Physical Component Scale score was 39.4 (37.2-44.3) for post-traumatic stress disorder patients and 44.2 (39.1-46.8) for non post-traumatic stress disorder (p = 0.39). No significant difference in the quality of life in both populations was observed, and no independent risk factors of post-traumatic stress disorder was identified. CONCLUSION: Avalanche accidents may induce post-traumatic stress disorders among survivors in a comparable prevalence to the most traumatic event already studied. Early recognition and preventive measures should be set up in order to reduce the psychological burden in these victims. TRIAL REGISTRATION: NCT03936738 .

Hypothermic Cardiac Arrest - Retrospective cohort study from the International Hypothermia Registry.

AIM: The International Hypothermia Registry (IHR) was created to increase knowledge of accidental hypothermia, particularly to develop evidence-based guidelines and find reliable outcome predictors. The present study compares hypothermic patients with and without cardiac arrest included in the IHR. METHODS: Demographic, pre-hospital and in-hospital data, method of rewarming and outcome data were collected anonymously in the IHR between 2010 and 2020. RESULTS: Two hundred and one non-consecutive cases were included. The major causeof hypothermia was mountain accidents, predominantly in young men. Hypothermic Cardiac Arrest (HCA) occurred in 73 of 201 patients. Core temperature was significantly lower in the patients in cardiac arrest (25.0 vs. 30.0 °C, p < 0.001). One hundred and fifteen patients were rewarmed externally (93% with ROSC), 53 by extra-corporeal life support (ECLS) (40% with ROSC) and 21 with invasive internal techniques (71% with ROSC). The overall survival rate was 95% for patients with preserved circulation and 36% for those in cardiac arrest. Witnessed cardiac arrest and ROSC before rewarming were positive outcome predictors, asphyxia, coagulopathy, high potassium and lactate negative outcome predictors. CONCLUSIONS: This first analysis of 201 IHR patients with moderate to severe accidental hypothermia shows an excellent 95% survival rate for patients with preserved circulation and 36% for HCA patients. Witnessed cardiac arrest, restoration of spontaneous circulation, low potassium and lactate and absence of asphyxia were positive survival predictors despite hypothermia in young, healthy adults after mountaineering accidents. However, accidental hypothermia is a heterogenous entity that should be considered in both treatment strategies and prognostication.

Data and methods to calculate cut-off values for serum potassium and core temperature at hospital admission for extracorporeal rewarming of avalanche victims in cardiac arrest.

The data and estimation methods presented in this article are associated with the research article, "Cut-off values of serum potassium and core temperature at hospital admission for extracorporeal rewarming of avalanche victims in cardiac arrest: a retrospective multi-centre study" [1]. In this article we estimate recommended cut-off values for in-hospital triage with respect to extracorporeal rewarming. With only 6 survivors of 103 patients collected over a period of 20 years the ability to estimate reliable threshold values is limited. In addition, because the number of avalanche victims is also limited, a significantly larger dataset is unlikely to be obtained. We have therefore adapted two non-parametric estimation methods (bootstrapping and exact binomial distribution) to our specific needs and performed a simulations to confirm validity and reliability.

Accuracy of low-weight versus standard syringe infusion pump devices depending on altitude.

BACKGROUND: Intravenous drug infusions in critically ill patients require accurate syringe infusion pumps (SIPs). This is particularly important during transportation of critically ill patients by helicopter emergency medical services (HEMS), where altitude may influence device performance. Because weight is a real concern in HEMS, new low-weight devices are very appealing. The aim of this study was to compare infusion flow rates delivered by low-weight versus standard SIP devices, in the prehospital emergency medicine setting, at different altitudes. METHODS: We conducted a comparative bench study involving five SIP devices (two standard and three low-weight models) at 300, 1700 and 3000 m altitude. The primary endpoint was the flow rate delivered by SIPs for prespecified values. We used two methods to measure flow. The normative method consisted in measuring weight (method A) and the alternate method consisted in measuring instantaneous flow (method B). RESULTS: Using method A, no significant differences were found in median flow rates and interquartile range depending on device and altitude for a prespecified 10-mL/h flow. However, method B showed that low-weight SIPs delivered multiple sequential boluses with substantial variations (1.2-15.8 mL/h) rather than a prespecified continuous 5-mL/h flow. At 1700 m altitude, the interquartile range of delivered flows increased only for low-weight devices (p for interaction< 0.001). CONCLUSIONS: Despite satisfactory normative tests, low-weight SIPs deliver discontinuous flow with potential clinical implications for critically ill patients receiving vasoactive drugs. This study also highlights a thus far unknown negative impact of altitude on SIP function. We believe that normative requirements for SIP approval should be revised accordingly.

Cut-off values of serum potassium and core temperature at hospital admission for extracorporeal rewarming of avalanche victims in cardiac arrest: A retrospective multi-centre study.

AIM: Evidence of existing guidelines for the on-site triage of avalanche victims is limited and adherence suboptimal. This study attempted to find reliable cut-off values for the identification of hypothermic avalanche victims with reversible out-of-hospital cardiac arrest (OHCA) at hospital admission. This may enable hospitals to allocate extracorporeal life support (ECLS) resources more appropriately while increasing the proportion of survivors among rewarmed victims. METHODS: All avalanche victims with OHCA admitted to seven centres in Europe capable of ECLS from 1995 to 2016 were included. Optimal cut-off values, for parameters identified by logistic regression, were determined by means of bootstrapping and exact binomial distribution and served to calculate sensitivity, rate of overtriage, positive and negative predictive values, and receiver operating curves. RESULTS: In total, 103 avalanche victims with OHCA were included. Of the 103 patients 61 (58%) were rewarmed by ECLS. Six (10%) of the rewarmed patients survived whilst 55 (90%) died. We obtained optimal cut-off values of 7 mmol/L for serum potassium and 30 °C for core temperature. CONCLUSION: For in-hospital triage of avalanche victims admitted with OHCA, serum potassium accurately predicts survival. The combination of the cut-offs 7 mmol/L for serum potassium and 30 °C for core temperature achieved the lowest overtriage rate (47%) and the highest positive predictive value (19%), with a sensitivity of 100% for survivors. The presence of vital signs at extrication is strongly associated with survival. For further optimisation of in-hospital triage, larger datasets are needed to include additional parameters.

Hypothermia outcome prediction after extracorporeal life support for hypothermic cardiac arrest patients: The HOPE score.

AIMS: Currently, the decision to initiate extracorporeal life support for patients who suffer cardiac arrest due to accidental hypothermia is essentially based on serum potassium level. Our goal was to build a prediction score in order to determine the probability of survival following rewarming of hypothermic arrested patients based on several covariates available at admission. METHODS: We included consecutive hypothermic arrested patients who underwent rewarming with extracorporeal life support. The sample comprised 237 patients identified through the literature from 18 studies, and 49 additional patients obtained from hospital data collection. We considered nine potential predictors of survival: age; sex; core temperature; serum potassium level; mechanism of hypothermia; cardiac rhythm at admission; witnessed cardiac arrest, rewarming method and cardiopulmonary resuscitation duration prior to the initiation of extracorporeal life support. The primary outcome parameter was survival to hospital discharge. RESULTS: Overall, 106 of the 286 included patients survived (37%; 95% CI: 32-43%), most (84%) with a good neurological outcome. The final score included the following variables: age, sex, core temperature at admission, serum potassium level, mechanism of cooling, and cardiopulmonary resuscitation duration. The corresponding area under the receiver operating characteristic curve was 0.895 (95% CI: 0.859-0.931) compared to 0.774 (95% CI: 0.720-0.828) when based on serum potassium level alone. CONCLUSIONS: In this large retrospective study we found that our score was superior to dichotomous triage based on serum potassium level in assessing which hypothermic patients in cardiac arrest would benefit from extracorporeal life support. External validation of our findings is required.

Management of Multi-Casualty Incidents in Mountain Rescue: Evidence-Based Guidelines of the International Commission for Mountain Emergency Medicine (ICAR MEDCOM).

Blancher, Marc, François Albasini, Fidel Elsensohn, Ken Zafren, Natalie Hölzl, Kyle McLaughlin, Albert R. Wheeler III, Steven Roy, Hermann Brugger, Mike Greene, and Peter Paal. Management of multi-casualty incidents in mountain rescue: Evidence-based guidelines of the International Commission for Mountain Emergency Medicine (ICAR MEDCOM). High Alt Med Biol. 19:131-140, 2018. INTRODUCTION: Multi-Casualty Incidents (MCI) occur in mountain areas. Little is known about the incidence and character of such events, and the kind of rescue response. Therefore, the International Commission for Mountain Emergency Medicine (ICAR MEDCOM) set out to provide recommendations for the management of MCI in mountain areas. MATERIALS AND METHODS: Details of MCI occurring in mountain areas related to mountaineering activities and involving organized mountain rescue were collected. A literature search using (1) PubMed, (2) national mountain rescue registries, and (3) lay press articles on the internet was performed. The results were analyzed with respect to specific aspects of mountain rescue. RESULTS: We identified 198 MCIs that have occurred in mountain areas since 1956: 137 avalanches, 38 ski lift accidents, and 23 other events, including lightning injuries, landslides, volcanic eruptions, lost groups of people, and water-related accidents. DISCUSSION: General knowledge on MCI management is required. Due to specific aspects of triage and management, the approach to MCIs may differ between those in mountain areas and those in urban settings. CONCLUSIONS: Mountain rescue teams should be prepared to manage MCIs. Knowledge should be reviewed and training performed regularly. Cooperation between terrestrial rescue services, avalanche safety authorities, and helicopter crews is critical to successful management of MCIs in mountain areas.

The impact of hypothermia on serum potassium concentration: A systematic review.

BACKGROUND: Blood potassium is the main prognostic biomarker used for triage in hypothermic cardiac arrest. The aim of this review was to assess the impact of hypothermia on blood potassium levels and compare the underlying pathophysiological theories. METHODS: The Medline electronic database was searched via PubMed for articles published from January 1970 to December 2016. The search strategy included studies related to hypothermia and potassium levels. The relevant literature on clinical studies and experimental studies was reviewed by the authors. RESULTS: Among the 50 studies included in the review, 39 (78%) reported a decrease in blood potassium levels upon hypothermia onset. Hypothermic hypokalaemia is linked to an intracellular shift rather than an actual net loss. The intracellular shift is caused by a variety of factors such as enhanced functioning of Na+K+ATPase, beta-adrenergic stimulation, pH and membrane stabilisation in deep hypothermia. In contrast, hypothermia can act as an aggravating factor in severe trauma with hyperkalaemia being an indicator of an irreversible state of cell death. An increase in the blood potassium level during hypothermia may result from a lack of enzyme functioning at cold temperatures and blocked active transport. CONCLUSION: Hypothermia causes an initial decrease of potassium levels; however, the final stage of hypothermic cardiac arrest can induce hyperkalaemia due to cell lysis and final depolarisation. Better understanding the physiopathology of potassium levels during accidental hypothermia could be critically important to better select patients who could benefit from aggressive resuscitation therapy such as extracorporeal cardiopulmonary resuscitation.

Survival of cardiac arrest patients on ski slopes: A 10-year analysis of the Northern French Alps Emergency Network.

AIM: Intense physical activity, cold and altitude make mountain sports a cause of increased risk of out-of-hospital cardiac arrest (OHCA). The difficulties of pre-hospital management related to this challenging environment could be mitigated by the presence of ski-patrollers in ski areas and use of helicopters for medical rescue. We assess whether this particular situation positively impacts the chain of survival compared to the general population. METHODS: Analysis of prospectively collected data from the cardiac arrest registry of the Northern French Alps Emergency Network (RENAU) from 2004 to 2014. RESULTS: 19,341 OHCAs were recorded during the period, including 136 on-slope events. Compared to other OHCAs, on-slope patients were younger (56 [40-65] vs. 66 [52-79] years, p<0.001) and more often in shockable initial rhythm (41.2% vs 20.1%, p<0.001). Resuscitation was more frequently started by a witness (43.4% vs 26.8%, p<0.001) and the time to the first electric shock was shorter (7.5min vs 14min, p<0.001), whereas time to the advanced life support (ALS) rescue arrival did not differ. The 30-day survival rate was higher for on-slope arrests (21.3% vs 5.9%, p<0.001, RR=3.61). In multivariate analysis, on-slope CA remained a positive 30-day survival factor with a 2.6 odds ratio (95% confidence interval, 1.42-4.81, p=0.002). CONCLUSION: Despite difficult access and management conditions, patients undergoing OHCAs on ski slopes presented a higher survival rate, possibly explained by a healthier population, the efficiency of resuscitation by ski-patrols and similar time to ALS facilities compared to other cardiac arrests.

Prognostic factors for extracorporeal cardiopulmonary resuscitation recipients following out-of-hospital refractory cardiac arrest. A systematic review and meta-analysis.

PURPOSE: Association estimates between baseline characteristics and outcomes are imprecise and inconsistent among extracorporeal cardiopulmonary resuscitation (ECPR) recipients following refractory out-of-hospital cardiac arrest (OHCA). This systematic review and meta-analysis aimed to investigate the prognostic significance of pre-specified characteristics for OHCA treated with ECPR. METHODS: The Medline electronic database was searched via PubMed for articles published from January 2000 to September 2016. The electronic search was supplemented by scanning the reference lists of retrieved articles and contacting field experts. Eligible studies were historical and prospective cohort studies of adult patients undergoing ECPR following OHCA. RESULTS: Fifteen primary studies were included, totaling 841 participants. The median prevalence of the primary outcome (i.e., short- or long-term survival for five studies and cerebral performance for ten studies) was 15% (range, 0-50%). The primary outcome was associated with an increased odds ratio of initial shockable cardiac rhythm (2.20; 95% confidence interval [CI], 1.30-3.72; P=0.003), shorter low-flow duration (geometric mean ratio, 0.90; 95% CI, 0.81-0.99; P=0.04), higher arterial pH value (difference, 0.12; 95% CI, 0.03-0.22; P=0.01) and lower serum lactate concentration (difference, -3.52mmol/L; 95% CI, -5.05 to -1.99; P<0.001). No significant association was found between the primary outcome and patient age (the odds of female gender and bystander CPR attempt. CONCLUSION: Observational evidence from published primary studies indicates that shorter low-flow duration, shockable cardiac rhythm, higher arterial pH value and lower serum lactate concentration on hospital admission are associated with better outcomes for ECPR recipients after OHCA.

Outcome after severe accidental hypothermia in the French Alps: A 10-year review.

OBJECTIVE: To describe the factors associated with outcome after accidental deep hypothermia. METHODS: We conducted a retrospective cohort study on patients with accidental hypothermia (core temperature <28 °C) admitted to a Level I emergency room over a 10-year period. RESULTS: Forty-eight patients were included with a median temperature of 26 °C (range, 16.3-28 °C) on admission. The etiology of hypothermia was exposure to a cold environment (n = 27), avalanche (n = 13) or immersion in cold water (n = 8). Mean age was 47 ± 22 years, and 58% were males. Thirty-two patients had a cardiac arrest (CA): 15 patients presented unwitnessed cardiac arrest (UCA) and 17 patients presented rescue collapse (RC). Extracorporeal life support (ECLS) was implemented in 21 patients with refractory cardiac arrest and in two patients with hemodynamic instability. Overall mortality was 50%. For cardiac arrest patients, only three out of 15 patients with UCA survived at day 28, whereas eight out of 17 patients with RC survived. The cerebral performance category score was 4 for all the survivors of UCA and 1 [range, 1-2] for survivors of RC. Patients with poor outcome presented more UCA, a lower pH, a higher serum potassium, creatinine, serum sodium or lactate level as well as more severe coagulation disorders. CONCLUSION: Cardiac arrest related to rescue collapse was associated with favorable outcome. On-scene rescue collapse should prompt prolonged resuscitation and ECLS rewarming in all CA patients with deep hypothermia. Conversely, unwitnessed cardiac arrest was associated with unfavorable outcome and will likely not benefit from ECLS.