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Objectives: To test if impaired oxygenation or major haemodynamic instability at the time of emergency intensive care transport, from a smaller admitting hospital to a tertiary care centre, are predictors of long-term mortality.

Design: Retrospective observational study. Impaired oxygenation was defined as oxyhaemoglobin %–inspired oxygen fraction ratio (S/F ratio)<100. Major haemodynamic instability was defined as a need for treatment with norepinephrine infusion to sustain mean arterial pressure (MAP) at or above 60 mm Hg or having a mean MAP <60. Logistic regression was used to assess mortality risk with impaired oxygenation or major haemodynamic instability.

Setting: Sparsely populated Northern Sweden. A fixed-wing interhospital air ambulance system for critical care serving 900 000 inhabitants.

Participants: Intensive care cases transported in fixed-wing air ambulance from outlying hospitals to a regional tertiary care centre during 2000–2016 for adults (16 years old or older). 2142 cases were included.

Primary and secondary outcome measures: All-cause mortality at 3 months after transport was the primary outcome, and secondary outcomes were all-cause mortality at 1 and 7 days, 1, 6 and 12 months.

Results: S/F ratio <100 was associated with increased mortality risk compared with S/F>300 at all time-points, with adjusted OR 6.3 (2.5 to 15.5, p<0.001) at 3 months. Major haemodynamic instability during intensive care unit (ICU) transport was associated with increased adjusted OR of all-cause mortality at 3 months with OR 2.5 (1.8 to 3.5, p<0.001).

Conclusion: Major impairment of oxygenation and/or major haemodynamic instability at the time of ICU transport to get to urgent tertiary intervention is strongly associated with increased mortality risk at 3 months in this cohort. These findings support the conclusion that these conditions are markers for many fold increase in risk for death notable already at 3 months after transport for patients with these conditions.

Objective: We assessed the mortality risk related to the time for intensive care unit transport in a geographically large regional health care system.

Methods: Patient-level data from critical care ambulance missions were analyzed for 2,067 cases, mission time, and relevant patient factors. Mission time was used as a surrogate for the “distance” to tertiary care, and mortality at 7 days and other intervals was assessed.

Results: No increased mortality risk was found at 7 days in an unadjusted regression analysis (odds ratio = 1.00; range, 0.999-1.002; P = .66). In a secondary analysis, an increased mortality risk was observed in longer mission time subgroups and at later mortality assessment intervals (> 375 mission minutes and 90-day mortality; adjusted hazard ratio = 1.56; range, 1.07-2.28; P = .02). Negative changes in oxygenation and hemodynamic status and transport-related adverse events were associated with the longest flight times. Measurable but small changes during flight were noted for mean arterial pressure and oxygenation.

Conclusion: The main finding was that there was no overall difference in mortality risk based on mission time. We conclude that transport distances or accessibility to critical care in the tertiary care center in a geographically large but sparsely populated region is not clearly associated with mortality risk.

Introduction: Hospitals, including intensive care units (ICUs), can be subject to threat from fire and require urgent evacuation. 

Hypothesis: The hypothesis was that the current preparedness for ICU evacuation for fire in the national public hospital system in a wealthy country was very good, using Sweden as model. 

Methods: An already validated questionnaire for this purpose was adapted to national/local circumstances and translated into Swedish. It aimed to elicit information concerning fire response planning, personnel education, training, and exercises. Questionnaire results (yes/no answers) were collected and answers collated to assess grouped responses. Frequencies of responses were determined. 

Results: While a written hospital plan for fire response and evacuation was noted by all responders, personnel familiarity with the plan was less frequent. Deficiencies were reported concerning all categories: lack of written fire response plan for ICU, lack of personnel education in this, and lack of practical exercises to practice urgent evacuation in the event of fire. 

Conclusions: These findings were interpreted as an indication of risk for worse consequences for patients in the event of fire and ICU evacuation among the hospitals in the country that was assessed, despite clear regulations and requirements for these. The exact reasons for this lack of compliance with existing laws was not clear, though there are many possible explanations. To remedy this, more attention is needed concerning recognizing risk related to lack of preparedness. Where there exists a goal of high-quality work in the ICU, this should include general leadership and medical staff preparedness in the event of urgent ICU evacuation.

BACKGROUND: Post-craniotomy intracranial air can be present in patients scheduled for air ambulance transport to their home hospital. We aimed to assess risk for in-flight intracranial pressure (ICP) increases related to observed intracranial air volumes, hypothetical sea level pre-transport ICP, and different potential flight levels and cabin pressures. METHODS: A cohort of consecutive subdural hematoma evacuation patients from one University Medical Centre was assessed with post-operative intracranial air volume measurements by computed tomography. Intracranial pressure changes related to estimated intracranial air volume effects of changing atmospheric pressure (simulating flight and cabin pressure changes up to 8000 ft) were simulated using an established model for intracranial pressure and volume relations. RESULTS: Approximately one third of the cohort had post-operative intracranial air. Of these, approximately one third had intracranial air volumes less than 11 ml. The simulation estimated that the expected changes in intracranial pressure during 'flight' would not result in intracranial hypertension. For intracranial air volumes above 11 ml, the simulation suggested that it was possible that intracranial hypertension could develop 'inflight' related to cabin pressure drop. Depending on the pre-flight intracranial pressure and air volume, this could occur quite early during the assent phase in the flight profile. DISCUSSION: These findings support the idea that there should be radiographic verification of the presence or absence of intracranial air after craniotomy for patients planned for long distance air transport. CONCLUSIONS: Very small amounts of air are clinically inconsequential. Otherwise, air transport with maintained ground-level cabin pressure should be a priority for these patients.

Background: Cold injuries are rare but important causes of hospitalization. We aimed to identify the magnitude of cold injury hospitalization, and assess causes, associated factors and treatment routines in a subarctic region. Methods: In this retrospective analysis of hospital records from the 4 northernmost counties in Sweden, cases from 2000-2007 were identified from the hospital registry by diagnosis codes for accidental hypothermia, frostbite, and cold-water drowning.Results were analyzed for pre-hospital site events, clinical events in-hospital, and complications observed with mild (temperature 34.9 - 32 degrees C), moderate (31.9 - 28 degrees C) and severe (<28 degrees C), hypothermia as well as for frostbite and cold-water drowning. Results: From the 362 cases, average annual incidences for hypothermia, frostbite, and cold-water drowning were estimated to be 3.4/100 000, 1.5/100 000, and 0.8/100 000 inhabitants, respectively. Annual frequencies for hypothermia hospitalizations increased by approximately 3 cases/year during the study period. Twenty percent of the hypothermia cases were mild, 40% moderate, and 24% severe. For 12%, the lowest documented core temperature was 35 degrees C or higher, for 4% there was no temperature documented. Body core temperature was seldom measured in pre-hospital locations. Of 362 cold injury admissions, 17 (5%) died in hospital related to their injuries. Associated co-factors and co-morbidities included ethanol consumption, dementia, and psychiatric diagnosis. Conclusions: The incidence of accidental hypothermia seems to be increasing in this studied sub-arctic region. Likely associated factors are recognized (ethanol intake, dementia, and psychiatric diagnosis).

Background: There are three different types of ambulance systems, all of which can manage the same secondary intensive care patient transport mission: road ambulance, rotor-wing ambulance, and fixed-wing ambulance. We hypothesized that costs for specific transport distances would differ between systems. We aimed to analyze distances and observed times for ambulance intensive care secondary transport missions together with system costs to assess this. Methods: We prospectively collected data for consecutive urgent intensive care transports into the regional tertiary care hospital in the northern region of Sweden. Distances and transport times were gathered, and a cost model was generated based on these together with fixed and operating costs from the three different ambulance systems. Distance-cost and time-cost estimations were then generated for each transport system. Results: Road ambulance cost relatively less for shorter distances (within 250 kilometers/155 miles) but were relatively time ineffective. The rotor-wing systems were most expensive regardless of distance; but were most time-effective up to 400-500 km (248-310 miles). Fixed-wing systems were more cost-effective for longer distance (300 km/186 miles), and time effective for transports over 500 km (310 miles). Conclusions: In summary, based on an economic model developed from observed regional ICU patient transports, and cost estimations, different ambulance system cost-distances could be compared. Distance-cost and time results show that helicopters can be effective up to moderate ICU transport distances (400-500), though are expensive to operate. For longer ICU patient transports, fixed-wing transport systems are both cost and time effective compared to helicopter-based systems.

INTRODUCTION: Continuous positive airway pressure (CPAP) is used in air ambulances to treat patients with impaired oxygenation. Differences in mechanical principles between CPAP devices may affect their performance at different ambient air pressures as will occur in an air ambulance during flight. METHODS: Two different CPAP systems, a threshold resistor device and a flow resistor device, at settings 5 and 10 cm H₂O were examined. Static pressure, static airflow and pressure during simulated breathing were measured at ground level and at three different altitudes (2400 m (8 kft), 3000 m (10 kft) and 10700 m (35 kft)). RESULTS: When altitude increased, the performance of the two CPAP systems differed during both static and simulated breathing pressure measurements. With the threshold resistor CPAP, measured pressure levels were close to the preset CPAP level. Static pressure decreased 0.71 ± 0.35 cm H₂O, at CPAP 10 cm H₂O, comparing ground level and 35 kft. With the flow resistor CPAP, as the altitude increased CPAP produced pressure levels increased. At 35 kft, the increase was 5.13 ± 0.33 cm H₂O at CPAP 10 cm H₂O. DISCUSSION: The velocity of airflow through the flow resistor CPAP device is strongly influenced by reduced ambient air pressure leading to a higher delivered CPAP effect than the preset CPAP level. Threshold resistor CPAP devices seem to have robust performance regardless of altitude. Thus, the threshold resistor CPAP device is probably more appropriate for CPAP treatment in an air ambulance cabin, where ambient pressure will vary during patient transport.

PURPOSE: Differences among individuals concerning susceptibility to local cold injury following acute cold exposure may be related to function of the autonomic nervous system. We hypothesized that there are differences in heart rate variability (HRV) between individuals with normal or more pronounced vasoconstriction following cold exposure and that there is an adaptation related to prolonged cold exposure in autonomic nervous system response to cold stimuli.

METHODS: Seventy-seven young men performed a cold provocation test, where HRV was recorded during cold hand immersion and recovery. Forty-three subjects were re-examined 15 months later, with many months of cold weather training between the tests. Subjects were analyzed as 'slow' and 'normal' rewarmers according to their thermographic rewarming pattern.

RESULTS: For the 'pre-training' test, before cold climate exposure, normal rewarmers had higher power for low-frequency (P(LF)) and high-frequency (P(HF)) HRV components during the cold provocation test (ANOVA for groups: p = 0.04 and p = 0.005, respectively). There was an approximately 25 % higher P(HF) at the start in normal rewarmers, in the logarithmic scale. Low frequency-to-high frequency ratio (P(LF)/P(HF)) showed lower levels for normal rewarmers (ANOVA for groups: p = 0.04). During the 'post-training' cold provocation test, both groups lacked the marked increase in heart rate that occurred during cold exposure at the 'pre-training' setting. After cold acclimatization (post-training), normal rewarmers showed lower resting power values for the low-frequency and high-frequency HRV components. After winter training, the slow rewarmers showed reduced low-frequency power for some of the cold provocation measurements but not all (average total P(LF), ANOVA p = 0.05), which was not present before winter training.

CONCLUSIONS: These HRV results support the conclusion that cold adaptation occurred in both groups. We conclude that further prospective study is needed to determine whether cold adaptation provides protection to subjects at higher risk for cold injury, that is, slow rewarmers.

Background: (Papers I and II) The objectives were to first determine incidence and contributing factors to cold-related injuries in northern Sweden, both those that led to hospitalization and those that led to fatality.  (Papers III and IV) A further aim was to assess post-cooling hand-rewarming responses and effects of training in a cold environment, both on fingertip rewarming and on function of the autonomic nervous system, to evaluate if there was adaptation related to prolonged occupational cold exposure.

Methods:  In a retrospective analysis, cases of accidental cold-related injury with hospital admission in northern Sweden during 2000-2007 were analyzed (Paper I).  Cases of fatal hypothermia in the same region during 1992-2008 were analyzed (Paper II).  A cohort of volunteers was studied before and after many months of occupational cold exposure. Subject hand rewarming response was measured after a cold hand immersion provocation and categorized as slow, moderate or normal in rewarming speed.  This cold provocation and rewarming assessment was performed before and after their winter training.  (Paper III).  Heart rate variability (HRV) was analyzed from the same cold provocation/recovery sequences (Paper IV).

Results:  (Paper I) For the 379 cases of hospitalization for cold-related injury, annual incidences for hypothermia, frostbite, and drowning were 3.4/100,000, 1.5/100,000, and 1.0/100,000 inhabitants, respectively.  Male gender was more frequent for all categories.  Annual frequencies for hypothermia hospitalizations increased during the study period.  Hypothermia degree and distribution of cases were 20 % mild (between 32 and 35ºC), 40% moderate (31.9 to 28ºC), and 24% severe (< 28ºC), while 12% had temperatures over 35.0ºC.  (Paper II) The 207 cases of fatal hypothermia showed an annual incidence of 1.35 per 100,000 inhabitants, 72% in rural areas, 93% outdoors, 40% found within 100 meters of a building.  Paradoxical undressing was documented in 30%.  Ethanol was detected in femoral vein blood in 43%. Contributing co-morbidity was common including heart disease, previous stroke, dementia, psychiatric disease, alcoholism, and recent trauma.  (Paper III) Post-training, baseline fingertip temperatures and cold recovery variables in terms of final rewarming fingertip temperature and vasodilation time increased significantly in moderate and slow rewarmers.  Cold-related injury (frostbite) during winter training occured disproportionately more often in slow rewarmers (4 of the 5 injuries).  (Paper IV) At ‘pre- winter-training’, normal rewarmers had higher power for low frequency and high frequency heart rate variability.  After cold acclimatization (post-training), normal rewarmers showed lower resting power values for the low frequency and high frequency heart rate variability components. 

Conclusions: Hypothermia and cold injury continues to cause injury and hospitalization in the northern region of Sweden.  Assessment and management is not standardized across hospitals.  With the identification of groups at high risk for fatal hypothermia, it should be possible to reduce the incidence, particularly for highest risk subjects; rural, living alone, alcohol-imbibing, and psychiatric diagnosis-carrying citizens.  Long-term cold-weather training may affect hand rewarming patters after a cold provocation, and a warmer baseline hand temperature with faster rewarming after a cold provocation may be associated with less general risk for frostbite.  Heart rate variability results support the conclusion that cold adaptation in the autonomic nervous system occurred in both groups, though the biological significance of this is not yet clear.

Objectives. To determine the incidence as well as contributing factors to fatal hypothermia.

Study design. Retrospective, registry-based analysis.

Methods. Cases of fatal hypothermia were identified in the database of the National Board of Forensic Medicine for the 4 northernmost counties of Sweden and for the study period 1992-2008. Police reports, medical records and autopsy protocols were studied.

Results. A total of 207 cases of fatal hypothermia were noted during the study period, giving an annual incidence of 1.35 per 100,000 inhabitants. Seventy-two percent occurred in rural areas, and 93% outdoors. Many (40%) were found within approximately 100 meters of a building. The majority (75%) occurred during the colder season (October to March). Some degree of paradoxical undressing was documented in 30%. Ethanol was detected in femoral vein blood in 43% of the victims. Contributing co-morbidity was common and included heart disease, earlier stroke, dementia, psychiatric disease, alcoholism, and recent trauma.

Conclusions. With the identification of groups at high risk for fatal hypothermia, it should be possible to reduce risk through thoughtful interventions, particularly related to the highest risk subjects (rural, living alone, alcohol-imbibing, and psychiatric diagnosis-carrying) citizens.