Factors affecting survival from avalanche burial--a randomised prospective porcine pilot study.

BACKGROUND AND AIM: The majority of avalanche victims who sustain complete burial die within 35min due to asphyxia and injuries. After 35min, survival is possible only in the presence of a patent airway, and an accompanying air pocket around the face may improve survival. At this stage hypothermia is assumed to be an important factor for survival because rapid cooling decreases oxygen consumption; if deep hypothermia develops before cardiac arrest, hypothermia may be protective and prolong the time that cardiac arrest can be survived. The aim of the study was to investigate the combined effects of hypoxia, hypercapnia and hypothermia in a porcine model of avalanche burial. METHODS: Eight piglets were anaesthetised, intubated and buried under snow, randomly assigned to an air pocket (n=5) or ambient air (n=3) group. RESULTS: Mean cooling rates in the first 10min of burial were -19.7±4.7°Ch(-1) in the air pocket group and -13.0±4.4°Ch(-1) in the ambient air group (P=0.095); overall cooling rates between baseline and asystole were -4.7±1.4°Ch(-1) and -4.6±0.2°Ch(-1) (P=0.855), respectively. In the air pocket group cardiac output (P=0.002), arterial oxygen partial pressure (P=0.001), arterial pH (P=0.002) and time to asystole (P=0.025) were lower, while arterial carbon dioxide partial pressure (P=0.007) and serum potassium (P=0.042) were higher compared to the ambient air group. CONCLUSION: Our results demonstrate that hypothermia may develop in the early phase of avalanche burial and severe asphyxia may occur even in the presence of an air pocket.

Factors impacting on the activation and approach times of helicopter emergency medical services in four Alpine countries.

BACKGROUND: The outcome of severely injured or ill patients can be time dependent. Short activation and approach times for emergency medical service (EMS) units are widely recognized to be important quality indicators. The use of a helicopter emergency medical service (HEMS) can significantly shorten rescue missions especially in mountainous areas. We aimed to analyze the HEMS characteristics that influence the activation and approach times. METHODS: In a multi-centre retrospective study, we analyzed 6121 rescue missions from nine HEMS bases situated in mountainous regions of four European countries. RESULTS: We found large differences in mean activation and approach times among HEMS bases. The shortest mean activation time was 2.9 minutes; the longest 17.0 minutes. The shortest mean approach time was 10.4 minutes; the longest 45.0 minutes. Short times are linked (p < 0.001) to the following conditions: helicopter operator is not state owned; HEMS is integrated in EMS; all crew members are at the same location; doctors come from state or private health institutions; organization performing HEMS is privately owned; helicopters are only for HEMS; operation area is around 10.000 km2; HEMS activation is by a dispatching centre of regional government who is in charge of making decisions; there is only one intermediator in the emergency call; helicopter is equipped with hoist or fixed line; HEMS has more than one base with helicopters, and one team per base; closest neighboring base is 90 km away; HEMS is about 20 years old and has more than 650 missions per year; and modern helicopters are used. CONCLUSIONS: An improvement in HEMS activation and approach times is possible. We found 17 factors associated with shorter times.

Correlation between avalanche emergencies and avalanche danger forecast in the alpine region of Tyrol.

OBJECTIVE: We investigated whether frequency of avalanche accidents corresponds with the danger assessment given in avalanche hazard tables and with topographic factors of the avalanche origin. METHODS: A retrospective review of official avalanche surveillance data and of medical reports from helicopter-based emergency medical systems was conducted. RESULTS: Most victims involved in avalanche accidents are ski tourers and off-piste skiers, about 90% are male, and age ranges from 10 to more than 70 years. Sixty-seven percent of accidents occurred when moderate and considerable danger was forecast. In 94.0% of accidents avalanches were triggered by victims themselves or by nearby recreationists; 32.6% of avalanche slides occurred on extremely steep slopes at gradients exceeding 40 degrees . Overall incidence of accidents before noon was 25.0%. Professional stand-by avalanche parties significantly contributed to rescuing avalanche victims, but the chance of survival is diminished when arrival was delayed. All patients who were able to free themselves from avalanche burial survived. Of those rescued by companions, 78.0% survived compared with only 10.0% of those rescued by organized rescue teams (P<0.001). CONCLUSION: Frequency of avalanche emergencies associated with outdoor leisure activities does not correspond with the danger forecast in avalanche hazard bulletins. There is need of a modified and regionally adjusted grading that makes allowance for experience and individual behavior of recreationists going in for backcountry leisure activities.

Coagulation changes and edema formation during long-distance bus travel.

Long-distance travel in a cramped position by aircraft or by bus and car has been suggested to be associated with an increased risk for thromboembolic events. Recently, we demonstrated moderate activation of coagulation after a long-haul flight. At present the single contributing factors (i.e. hypoxia and low humidity on board an aircraft and prolonged sitting in an aircraft, car or bus inducing venous stasis) have not yet been investigated. Therefore we measured markers of coagulation and fibrinolysis as well as functional parameters of coagulation using activated thrombelastography in 19 healthy volunteers before, during and after a real 10-h bus journey. In addition, changes in leg volume were measured. Thrombelastography revealed moderate activation of coagulation in all travelers, which was accompanied by a significant increase in prothrombin fragment F1 + 2. Thrombin-antithrombin III complexes and D-dimer remained unchanged, and tissue-type plasminogen activator and plasminogen-activator inhibitor 1 decreased after travel. After the travel we found a significant increase in leg volume that was exclusively distributed in the calf. We conclude that beside long-haul flights also long-distance bus travel induces a certain activation of the coagulation system. Thus, it is questionable whether hypoxia is the crucial risk factor for thromboembolic events after long-haul flights.

Changes of biochemical markers and functional tests for clot formation during long-haul flights.

INTRODUCTION: Long-haul flights have been suggested to be associated with an increased risk for thromboembolic events. Until now, changes in the coagulation system during an actual flight have not been investigated. MATERIALS AND METHODS: To explore whether any changes occur in the coagulation system during a real long-haul flight molecular markers for coagulation and fibrinolysis were measured in 20 volunteers (10 subjects with a low and 10 with a moderate risk for venous thromboembolism (VTE)) during and after a return flight from Vienna to Washington. In addition, functional measurements of coagulation were performed using activated thrombelastography. RESULTS: Thrombelastographic measurements revealed activation of coagulation in all passengers, who showed an increased activity of FVII and FVIII as well as suppressed fibrinolysis. There was no evidence of a pronounced thrombin and fibrin formation. We did not find any differences between both groups concerning coagulation changes. CONCLUSION: Long-haul flights induce a certain activation of the coagulation system. This activated coagulation could be a risk factor for VTE during long-haul flights mainly when other risk factors are present.