Short-term exposure to hypoxia for work and leisure activities in health and disease: which level of hypoxia is safe?

INTRODUCTION: Exposures to natural and simulated altitudes entail reduced oxygen availability and thus hypoxia. Depending on the level of hypoxia, the duration of exposure, the individual susceptibility, and preexisting diseases, health problems of variable severity may arise. Although millions of people are regularly or occasionally performing mountain sport activities, are transported by airplanes, and are more and more frequently exposed to short-term hypoxia in athletic training facilities or at their workplace, e.g., with fire control systems, there is no clear consensus on the level of hypoxia which is generally well tolerated by human beings when acutely exposed for short durations (hours to several days). CONCLUSIONS: Available data from peer-reviewed literature report adaptive responses even to altitudes below 2,000 m or corresponding normobaric hypoxia (F(i)O(2) > 16.4%), but they also suggest that most of exposed subjects without severe preexisting diseases can tolerate altitudes up to 3,000 m (F(i)O(2) > 14.5%) well. However, physical activity and unusual environmental conditions may increase the risk to get sick. Large interindividual variations of responses to hypoxia have to be expected, especially in persons with preexisting diseases. Thus, the assessment of those responses by hypoxic challenge testing may be helpful whenever possible.

Initial clinical experience with a 64-MDCT whole-body scanner in an emergency department: better time management and diagnostic quality?

BACKGROUND: The objective of this study was to assess time management and diagnostic quality when using a 64-multidetector-row computed tomography (MDCT) whole-body scanner to evaluate polytraumatized patients in an emergency department. METHODS: Eighty-eight consecutive polytraumatized patients with injury severity score (ISS) > or = 18 (mean ISS = 29) were included in this study. Documented and evaluated data were crash history, trauma mechanism, number and pattern of injuries, injury severity, diagnostics, time flow, and missed diagnoses. Data were stored in our hospital information system. Seven time intervals were evaluated. In particular, attention was paid to the "acquisition interval," the "reformatting and evaluation time" as well as the "CT time" (time from CT start to preliminary diagnosis). A standardized whole-body CT was performed. The acquired CT data together with automatically generated multiplanar reformatted images ("direct MPR") were transferred to a 3D rendering workstation. Diagnostic quality was determined on the basis of missed diagnoses. Head-to-toe scout images were possible because volume coverage was up to 2 m. Experienced radiologists at an affiliated workstation performed radiologic evaluation of the acquired datasets immediately after acquisition. RESULTS: The "acquisition interval" was 12 minutes +/- 4.9 minutes, the "reformatting and evaluation interval" 7.0 minutes +/- 2.1 minutes, and the "CT time" 19 minutes +/- 6.1 minutes. Altogether, 7 of 486 lesions were recognized but not communicated in the "reformatting and evaluation interval", and 10 injuries were initially missed and detected during follow-up. CONCLUSION: This study indicates that 64-MDCT saves time, especially in the "reformatting and evaluation interval." Diagnostic quality is high, as reflected by the small number of missed diagnoses.

The impact of avalanche rescue devices on survival.

BACKGROUND: Within Europe and North America, the median annual mortality from snow avalanches between 1994 and 2003 was 141. There are two commonly used rescue devices: the avalanche transceiver, which is intended to speed up locating a completely buried person, and the avalanche airbag, which aims to prevent the person from being completely buried. OBJECTIVE: This retrospective study aimed to evaluate whether these avalanche rescue devices had an effect on mortality. METHODS: The study population was 1504 persons who were involved in 752 avalanches either in Switzerland from 1990 to 2000 and from 2002 to 2003 (1296 persons, 86.2%) or in Austria from 1998 to 2004 (208 persons, 13.8%). RESULTS: Persons equipped with an avalanche airbag had a lower chance of dying (2.9% versus 18.9%; P=0.026, OR 0.09, n=1504). In persons who were completely buried, without visible or audible signs at the surface and who did not rescue themselves (n=317), we found a lower median duration of burial (25min versus 125min; P<0.001) and mortality (55.2% versus 70.6%; P<0.001, OR 0.26) in those using an avalanche transceiver than in those not using the device. CONCLUSIONS: Our data showed that both the avalanche airbag and the avalanche transceiver reduce mortality. However, to improve the evaluation of rescue devices in the future, the data collection procedures should be reviewed and prospective trials should be considered, as the reliability of retrospective studies is limited.

Blood coagulation activation and fibrinolysis during a downhill marathon run.

Prolonged physical exercise is associated with multiple changes in blood hemostasis. Eccentric muscle activation induces microtrauma of skeletal muscles, inducing an inflammatory response. Since there is a link between inflammation and coagulation we speculated that downhill running strongly activates the coagulation system. Thirteen volunteers participated in the Tyrolean Speed Marathon (42,195 m downhill race, 795 m vertical distance). Venous blood was collected 3 days (T1) and 3 h (T2) before the run, within 30 min after finishing (T3) and 1 day thereafter (T4). We measured the following key parameters: creatine kinase, myoglobin, thrombin-antithrombin complex, prothrombin fragment F1 + 2, D-dimer, plasmin-alpha(2)-antiplasmin complexes, tissue-type plasminogen activator antigen, plasminogen-activator-inhibitor-1 antigen and thrombelastography with ROTEM [intrinsic pathway (InTEM) clotting time, clot formation time, maximum clot firmness, alpha angle]. Thrombin generation was evaluated by the Thrombin Dynamic Test and the Technothrombin TGA test. Creatine kinase and myoglobin were elevated at T3 and further increased at T4. Thrombin-antithrombin complex, prothrombin fragment F1 + 2, D-dimer, plasmin-alpha(2)-antiplasmin complexes, tissue-type plasminogen activator antigen and plasminogen-activator-inhibitor-1 antigen were significantly increased at T3. ROTEM analysis exhibited a shortening of InTEM clotting time and clot formation time after the marathon, and an increase in InTEM maximum clot firmness and alpha angle. Changes in TGA were indicative for thrombin generation after the marathon. We demonstrated that a downhill marathon induces an activation of coagulation, as measured by specific parameters for coagulation, ROTEM and thrombin generation assays. These changes were paralleled by an activation of fibrinolysis indicating a preserved hemostatic balance.

Basic life support ventilation in mountain rescue. Official recommendations of the International Commission for Mountain Emergency Medicine (ICAR MEDCOM).

Cardiopulmonary resuscitation in the mountains usually has to be performed under difficult and hostile circumstances and sometimes for extended periods of time. Therefore, mountain rescuers should have the ability and the appropriate equipment to perform prolonged, efficient, and safe ventilation. Members of the International Commission for Mountain Emergency Medicine (ICAR MEDCOM) discussed the results of a literature review, focusing on the advantages and disadvantages of common ventilation techniques in basic life support and their training methods with specific respect to use in mountain rescue, and recommendations were proposed. Bystanders fear the potential risk of infection and lack the willingness to perform mouth-to-mouth ventilation, though the risk of infection is low. Mouth-to-mouth ventilation remains the standard technique for bystander ventilation and, in the absence of a barrier device, bystanders should not hesitate to ventilate a patient by this technique. For mountain rescue teams, we encourage the use of a barrier device for artificial ventilation. Mouth-to-mask ventilation devices are most likely to fulfill the requirements of being safe, simple, and efficient in the hands of a basic-trained rescuer. The use of a mouth-to-mask ventilation device is recommended for out-of-hospital ventilation in the mountains and should be part of the mountain rescuer's standard equipment. Bag-valve-mask ventilation is efficient, if performed by well-trained rescuers, but it leads to a low ventilation quality in the hands of a less experienced rescuer. It should be emphasized that regular training every 6 to 12 months is necessary to perform proper ventilation.

Comparison of mouth-to-mouth, mouth-to-mask and mouth-to-face-shield ventilation by lay persons.

OBJECTIVE AND METHODS: A prospective randomised study on 70 volunteers without previous first aid education (42 males, 28 females, mean age 17) was performed to compare mouth-to-mouth ventilation (MMV, n = 24) versus mouth-to-pocket-mask ventilation (MPV, n = 25) and mouth-to-face-shield ventilation (MFV, n =21), and to evaluate if an instruction period of 10 min would be sufficient to teach lay persons artificial ventilation. Every volunteer performed three ventilation series using a bench model of an unprotected airway. RESULTS: MMV and MPV show higher mean tidal volume (TV) than MFV (values of series 3: 976 +/- 454 and 868 +/- 459 versus 604 +/- 328 ml, P = 0.002 and P = 0.025, respectively). We found a higher inter-individual variation in TV than in previous studies (P = 0.031). The recommended TV of 700-1000 ml was reached in only 23%, most frequently with MPV (MMV 16.7%, MPV 32%, MFV 19%) but the difference was not significant (P = 0.391). However, we found a significantly higher percentage with a TV below 700 ml with MFV (MMV 33.3%, MPV 36%, MFV 66.7% P = 0.047) and a significantly higher percentage of TV exceeding 1000 ml with MMV (MMV 50%, MPV 32%, MFV 14.3%) (P = 0.039). "Stomach" inflation was highest with MMV (79.2%) followed by MPV (52%) and MFV (42.9%) (P = 0.034). We found further differences between the sexes; males produced a higher TV (P = 0.003) and a higher percentage of stomach inflation (P = 0.029). CONCLUSION: MPV showed the best ventilation quality. It resulted in a more adequate TV than MMV and MFV and lower stomach inflation than MMV. Only a relatively low percentage of ventilations were within the recommended range for TV and this may be related to the short training duration. We found different performances between the sexes, a high inter-individual variation and mainly a low ventilation quality. Therefore, further studies have to focus more on teaching duration, sex differences and ventilation quality.

Arginine vasopressin in advanced vasodilatory shock: a prospective, randomized, controlled study.

BACKGROUND: Vasodilatory shock is a potentially lethal complication of severe disease in critically ill patients. Currently, catecholamines are the most widely used vasopressor agents to support blood pressure, but loss of catecholamine pressor effects is a well-known clinical dilemma. Arginine vasopressin (AVP) has recently been shown to be a potent vasopressor agent to stabilize cardiocirculatory function even in patients with catecholamine-resistant vasodilatory shock. METHODS AND RESULTS: Forty-eight patients with catecholamine-resistant vasodilatory shock were prospectively randomized to receive a combined infusion of AVP and norepinephrine (NE) or NE infusion alone. In AVP patients, AVP was infused at a constant rate of 4 U/h. Hemodynamic, acid/base, single-organ, and tonometrically derived gastric variables were reported before the study and 1, 12, 24, and 48 hours after study entry. For statistical analysis, a mixed-effects model was used. AVP patients had significantly lower heart rate, NE requirements, and incidence of new-onset tachyarrhythmias than NE patients. Mean arterial pressure, cardiac index, stroke volume index, and left ventricular stroke work index were significantly higher in AVP patients. NE patients developed significantly more new-onset tachyarrhythmias than AVP patients (54.3% versus 8.3%). Gastrointestinal perfusion as assessed by gastric tonometry was better preserved in AVP-treated patients. Total bilirubin concentrations were significantly higher in AVP patients. CONCLUSIONS: The combined infusion of AVP and NE proved to be superior to infusion of NE alone in the treatment of cardiocirculatory failure in catecholamine-resistant vasodilatory shock.

A survey of emergency medical services in mountain areas of Europe and North America: official recommendations of the International Commission for Mountain Emergency Medicine (ICAR Medcom).

Survey of on-site treatment of patients in mountain areas of 14 countries in Europe and North America (nonresponder rate 33%) to compare emergency medical services. Around 37,535 ground rescuers and 747 helicopters are ready for evacuation of casualties and patients in mountain areas. And 1316 physicians and 50,967 paramedics take part in ground and air mountain rescue operations. In Europe, 63.2% of helicopters have a physician on board, 17.8% are staffed with a paramedic, and 19% have no medically trained personnel on board. In North America, 31.6% (p < 0.001) of helicopters are staffed with a doctor, 59.3% (p < 0.001) with a paramedic, and 9.1% (p < 0.001) have no medical personnel. The percentage of on-site treatment according to the recommendations of the International Liaison Committee on Resuscitation (ILCOR) or International Commission for Alpine Rescue (ICAR) varies among all countries (p < 0.001) and is positively related to the percentage of physician-staffed helicopters (r = 0.76, p < 0.001). Paramedics in 90.9% countries are obliged to be medically trained, but physicians only need to have a standardized training in emergency medicine in 50% (p < 0.042). On-site treatment according to ILCOR or ICAR recommendations is performed more often in countries where physicians are regularly involved in mountain rescue operations. However, no conclusions can be drawn from the data as to the efficiency of treatment. The data show a lack of medical education in specific, mountain rescue-related problems. Physicians involved should undergo suitable training.

Hypoxia and hypercapnia during respiration into an artificial air pocket in snow: implications for avalanche survival.

Snow avalanche case reports have documented the survival of skiers apparently without permanent hypoxic sequelae, after prolonged complete burial despite there being only a small air pocket on extrication. We investigated the underlying pathophysiological changes in a prospective, randomised 2 x 2 crossover study in 12 volunteers (28 tests) breathing into an artificial air pocket (1- or 2-l volume) in snow. Peripheral SpO(2), ETCO(2), arterialised capillary blood variables, air pocket O(2) and CO(2), snow density, and snow conditions at the inner surface of the air pocket were determined. SpO(2) decreased from a median of 99% (93-100%) to 88% (71-94%; P<0.001) within 4 min of breathing into the air pocket; the reduction was greater at 1 l, than 2 l, volume air pocket (P=0.013, intention to treat P=0.003) and correlated to snow density (r=0.50, P=0.021, partial correlation coefficient). ETCO(2) rose simultaneously from median 5.07 kPa (3.47-6.93 kPa) to 6.8 kPa (5.87-8.27 kPa; P<0.001), with consequent respiratory acidosis. Despite premature interruption due to hypoxia (SpO(2)

[Traveler's thrombosis: incidence, etiology, prevention]. / Die Reisethrombose: Häufigkeit, Ursachen, Prävention.

The number of persons traveling by airplane, railway or bus is on the increase. Recently, there has been a growing number of reports on travel-related disorders after long journeys, especially long-haul flights (i.e. deep venous thrombosis (DVT) and pulmonary thromboembolism (VTE), also known as "economy class syndrome" or "traveler's thrombosis"). The exact incidence of travel related thrombosis is not known. Contributing factors for DVT and VTE are sitting in a cramped position for hours, low humidity and lowered oxygen pressure in the aircraft cabin, reduced fluid intake and dehydration, as well as individual risk factors. In this review article definitions for risk groups (low, moderate and high risk for DVT and VTE) and recommendations for prevention (leg exercise, fluid intake, compression stockings and application of low molecular weight heparins) of travel related thrombosis, based on the outcome of a recent expert meeting, are presented.

Economic burden of illness imposed by severe sepsis in Austria.

INTRODUCTION: Sepsis is a life-threatening disease, requiring instant treatment in an intensive care unit (ICU). The aim of this study was to determine the direct and indirect costs occurring in Austria due to this disease. PATIENTS AND METHODS: Direct costs were calculated based on a retrospective chart analysis in four adult Austrian ICUs, evaluating 74 patient records from the years 2000/2001. Patients were identified to have suffered from severe sepsis using ACCP-definitions. Assessed resource use (medication, laboratory analysis, microbiology analysis, consumer-goods, diagnostic procedures, staff costs, and basic bed costs) was linked with related center specific costs to determine direct costs per patient. Indirect costs due to productivity losses were calculated using official statistical material. RESULTS: The mean length of ICU stay (LOS ICU) of a severely septic patient was 18.1 days. Overall ICU mortality was found to be 43.2% and showed no gender difference. The mean daily direct ICU costs of care for severely septic patients were [symbol: see text] 1,617 and the mean total direct ICU costs per septic patient were [symbol: see text] 28,582. In total costs, survivors were equally expensive as non-survivors ([symbol: see text] 28,699 vs. 28,463) although their length of study was considerably longer (21.9 vs. 13.2 days). Considering a range of patients with severe sepsis in Austria from 6,700 to 9,500 per year, total direct costs in Austria range from [symbol: see text] 192 million to [symbol: see text] 272 million. Indirect costs determined by productivity losses due to unfitness for work (temporary and permanent) and premature death amount to [symbol: see text] 484 million to [symbol: see text] 686 million in Austria per year (same incidence range). Total costs, i.e. burden of illness, combining direct costs with indirect costs, range from [symbol: see text] 676 million to [symbol: see text] 958 million. CONCLUSION: Patients with severe sepsis have a high mortality rate, spend prolonged periods of time in the ICU, and are expensive to treat. Indirect costs of severe sepsis due to productivity losses, particularly by premature death, are considerable.

Fluid management in traumatic shock: a practical approach for mountain rescue. Official recommendations of the International Commission for Mountain Emergency Medicine (ICAR MEDCOM).

Sumann, Günther, Peter Paal, Peter Mair, John Ellerton, Tore Dahlberg, Gregoire Zen-Ruffinen, Ken Zafren, and Hermann Brugger. Fluid management in traumatic shock: a practical approach for mountain rescue. High Alt. Med. Biol. 10:71-75, 2009.-The management of severe injuries leading to traumatic shock in mountains and remote areas is a great challenge for emergency physicians and rescuers. Traumatic brain injury may further aggravate outcome. A mountain rescue mission may face severe limitations from the terrain and required rescue technique. The mission may be characterized by a prolonged prehospital care time, where urban traumatic shock protocols may not apply. Yet optimal treatment is of utmost importance. The aim of this study is to establish scientifically supported recommendations for fluid management that are feasible for the physician or paramedic attending such an emergency. A nonsystematic literature search was performed; the results and recommendations were discussed among the authors and accepted by the International Commission for Mountain Emergency Medicine (ICAR MEDCOM). Diagnostic and therapeutic strategies are discussed, as well as limitations on therapy in mountain rescue. An algorithm for fluid resuscitation, derived from the recommendations, is presented in Fig. 1. Focused on the key criterion of traumatic brain injury, different levels of blood pressure are presented as a goal of therapy, and the practical means for achieving these are given.

Early intensive care unit intervention for trauma care: what alters the outcome?

This review focuses on early management of multiple trauma patients with traumatic brain injury. Early usage of multislice computed tomography can substantially shorten the time spent on diagnostic workup in the emergency room and, therefore, speeds the initiation of lifesaving interventions for the control of hemorrhage. The important role of hemostatic angiographic embolization and its timing, in addition to surgical control of bleeding in patients suffering from pelvic fracture or organ lesions, is emphasized. The ongoing controversy regarding the strategy of fluid resuscitation is discussed. The concept of permissive hypotension seems to be promising but is absolutely contraindicated in patients with traumatic brain injury. Coagulation management should be guided by coagulation monitoring, including thromboelastography. A novel approach to reduce major bleeding is the application of recombinant factor VIIa. Strong effort should be directed toward the management of traumatic brain injury and the maintenance of cerebral perfusion pressure. The optimization of treatment of patients with multiple trauma, including brain injury, is a multidisciplinary task.