Accidental cold-related injury leading to hospitalization in northern Sweden: an eight-year retrospective analysis.

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°C), moderate (31.9 - 28°C) and severe (<28°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°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).

Autonomic nerve system responses for normal and slow rewarmers after hand cold provocation: effects of long-term cold climate training.

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 (PLF) and high-frequency (PHF) HRV components during the cold provocation test (ANOVA for groups: p = 0.04 and p = 0.005, respectively). There was an approximately 25 % higher PHF at the start in normal rewarmers, in the logarithmic scale. Low frequency-to-high frequency ratio (PLF/PHF) 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 PLF, 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.

Fatal hypothermia: an analysis from a sub-arctic region.

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.

Hand cold recovery responses before and after 15 months of military training in a cold climate.

INTRODUCTION: The ability of fingers to rapidly rewarm following cold exposure is a possible indicator of cold injury protection. We categorized the post-cooling hand-rewarming responses of men before and after participation in 15 mo of military training in a cold environment in northern Sweden to determine: 1) if the initial rewarming category was related to the occurrence of local cold injury during training; and 2) if cold training affected subsequent hand-rewarming responses. METHODS: Immersion of the dominant hand in 10 degrees C water for 10 min was performed pre-training on 77 men. Of those, 45 were available for successful post-training retests. Infrared thermography monitored the dorsal hand during 30 min of recovery. Rewarming was categorized as normal, moderate, or slow based on mean fingertip temperature at the end of 30 min of recovery (TFinger,30) and the percentage of time that fingertips were vasodilated (%VD). RESULTS: Cold injury occurrence during training was disproportionately higher in the slow rewarmers (four of the five injuries). Post-training, baseline fingertip temperatures and cold recovery variables increased significantly in moderate and slow rewarmers: TFinger30 increased from 21.9 +/- 4 to 30.4 +/- 6 degrees C (Moderate), and from 17.4 +/- 0 to 22.3 +/- 7 degrees C (Slow); %VD increased from 27.5 +/- 16 to 65.9 +/- 34% (Moderate), and from 0.7 +/- 2 to 31.7 +/- 44% (Slow). CONCLUSIONS: Results of the cold recovery test were related to the occurrence of local cold injury during long-term cold-weather training. Cold training itself improved baseline and cold recovery in moderate and slow rewarmers.

The effects of a 1-year physical exercise programme on development of fatigue during a simulated ambulance work task.

The aim of the study was to evaluate the effects of individually prescribed physical exercise programmes on development of fatigue during the carrying of a loaded stretcher up and down the stairs. Nineteen ambulance personnel performed the training for 1 year. Testing occurred before and after 1 year of the training. Both the training group (n = 19) and the control group (n = 15) were assessed for physical capacity and lactate concentration in blood and ratings of perceived exertion during carrying a stretcher on the stairs. When comparisons were made between those who had been training three times/week for 1 year and the control group, lactate concentration was significantly decreased. In conclusion, markers of fatigue during stretcher carrying can be reduced by the use of individually prescribed physical exercise programmes.

Characteristics of cardiac arrest and resuscitation by age group: an analysis from the Swedish Cardiac Arrest Registry.

AIM: The objective of this study was to describe patients who experienced an out-of-hospital cardiac arrest (OHCA) by age group. METHODS: All patients who suffered from an OHCA between 1990 and 2005 and are included in the Swedish Cardiac Arrest Registry (n = 40,503) were classified into the following age groups: neonates, younger than 1 year; young children, between 1 and 4 years; older children, between 5 and 12 years; adolescents, between 13 and 17 years; young adults, between 18 and 35 years; adults not retired, between 36 and 64 years; adults retired, between 65 and 79 years; and older adults, 80 years or older. RESULTS: Ventricular fibrillation was lowest in young children (3%) and highest in adults (35%). Survival to 1 month was lowest in neonates (2.6%) and highest in older children (7.8%). Children (<18 years), young adults (18-35 years), and adults (>35 years) survived to 1 month 24.5%, 21.2%, and 13.6% of cases, respectively (P = .0003 for trend) when found in a shockable rhythm. The corresponding figures for nonshockable rhythms were 3.8%, 3.2%, and 1.6%, respectively (P < .0001 for trend). CONCLUSIONS: There is a large variability in characteristics and outcome among patients in various age groups who experienced an OHCA. Among the large age groups, there was a successive decline in survival with increasing age in shockable and nonshockable rhythms.

Stress monitoring of ambulance personnel during work and leisure time.

OBJECTIVES: The aim of the present study was to assess physiological and subjective stress markers during a 24-h ambulance work shift and during the next two work-free days, and relate these parameters to self-reported health complaints. METHODS: Twenty-six ambulance personnel were followed during a 24-h work shift and during the next two work-free days with electrocardiogram, cortisol assessments and diary notes. The ambulance personnel also performed tests of autonomic reactivity before and at the end of the work shift. The subjects were categorized into two groups according to their number of health complaints. RESULTS: In general, stress markers did not show differences between the work shift and leisure time. However, a modest deviation in heart rate variability pattern and higher morning cortisol values during work in comparison with work-free days were observed in personnel with many health complaints. CONCLUSIONS: Subjective and physiological characteristics of ambulance personnel did not indicate distinctive stress during the 24-h work shift. Relationships between frequent health complaints and specific work-related factors require further prospective studies.

Relationships between work-related factors and disorders in the neck-shoulder and low-back region among female and male ambulance personnel.

This cross-sectional study on a random sample of 1,500 ambulance personnel investigated the relationships between self-reported work-related physical and psychosocial factors, worry about work conditions, and musculoskeletal disorders among female and male ambulance personnel. Three different outcomes, complaints, activity limitation, and sick leave, for the neck-shoulder and low-back region, respectively, were chosen. Among the female personnel, physical demands was significantly associated with activity limitation in the neck-shoulder (OR 4.13) and low-back region (OR 2.17), and psychological demands with neck-shoulder (OR 2.37) and low-back (OR 2.28) complaints. Among the male personnel, physical demands was significantly associated with low-back complaints (OR 1.41) and activity limitation (OR 1.62). Psychological demands and lack of social support were significantly associated with neck-shoulder complaints (OR 1.86 and OR 1.58, respectively) and activity limitation (OR 3.46 and OR 1.71) as well as activity limitation due to low-back complaints (OR 2.22 and OR 1.63). Worry about work conditions was independently associated with activity limitation due to low-back complaints among the female (OR 5.28), and to both neck-shoulder and low-back complaints (OR 1.79 and OR 2.04, respectively) and activity limitation (OR 2.32 and OR 1.95) among the male personnel. In conclusion, the association patterns between physical and psychological demands and MSDs suggest opportunities for intervention.

Work-related psychosocial factors, worry about work conditions and health complaints among female and male ambulance personnel.

This study aimed at investigating the relationships between work-related psychosocial factors, worry about work conditions and health complaints (sleeping problems, headache and stomach symptoms) among female and male ambulance personnel. Out of 4000 ambulance personnel in Sweden, 1500 (300 female and 1200 male personnel) were randomly selected. They answered a questionnaire including items on self-reported health complaints, individual characteristics, work-related psychological demands, decision latitude, social support and worry about work conditions. Twenty-five per cent of the female and 20% of the male ambulance personnel reported two or more health complaints sometimes or often. According to the demand-control-support questionnaire, ambulance personnel reported a generally positive psychosocial work environment, although psychological demands were associated with sleeping problems, headache and stomach symptoms among both female and male ambulance personnel. Another factor that was significantly associated with health complaints among both genders was worry about work conditions. When worry about work conditions was added to the regression models, this variable took over the role from psychological demands as a predictor for health complaints among the female ambulance personnel. The prevalence of sleeping problems, headache and stomach symptoms were significantly associated with psychological demands among both female and male ambulance personnel. Notably, worry about work conditions seems to be an important risk factor for health complaints. This suggests that worry about work conditions should not be neglected when considering risk factors among ambulance personnel.

Efficacy of bystander CPR: intervention by lay people and by health care professionals.

BACKGROUND: Early cardiopulmonary resuscitation (CPR) by bystanders prior to the arrival of the rescue team has been shown to be associated with increased survival after out-of-hospital cardiac arrest. The aim of this survey was to evaluate the impact on survival of no bystander CPR, lay bystander CPR and professional bystander CPR. METHODS: Patients suffering an out-of-hospital cardiac arrest in Sweden between 1990 and 2002 who were given CPR and were not witnessed by the ambulance crew were included. RESULTS: In all, 29,711 patients were included, 36% of whom received bystander CPR prior to the arrival of the rescue team. Among the latter, 72% received CPR from lay people and 28% from professionals. Survival to 1 month was 2.2% among those who received no bystander CPR, 4.9% among those who received bystander CPR from lay people (p<0.0001) and 9.2% among those who received bystander CPR from professionals (p<0.0001 compared with bystander CPR by lay people). In a multivariate analysis, lay bystander CPR was associated with improved survival compared to no bystander CPR (OR: 2.04; 95% CI: 1.72-2.42), and professional bystander CPR was associated with improved survival compared to lay bystander CPR (OR: 1.37; 95% CI: 1.12-1.67). CONCLUSION: Among patients suffering an out-of-hospital cardiac arrest, bystander CPR by lay persons (excluding health care professionals) is associated with an increased chance of survival. Furthermore, there is a distinction between lay persons and health care providers; survival is higher when the latter perform bystander CPR. However, these results may not be explained by differences in the quality of CPR.

Factors associated with an increased chance of survival among patients suffering from an out-of-hospital cardiac arrest in a national perspective in Sweden.

AIM: To describe factors associated with an increased chance of survival among patients suffering from an out-of-hospital cardiac arrest in Sweden. PATIENTS AND METHODS: All patients suffering from an out-of-hospital cardiac arrest, which were not crew witnessed, in Sweden and in whom cardiopulmonary resuscitation (CPR) was attempted and who were registered in the Swedish Cardiac Arrest Registry. This registry covers about 85% of the Swedish population and has been running since 1990. RESULTS: In all, 33,453 patients, 71% of whom had a cardiac etiology, were included in the survey. The following were independent predictors for an increased chance of survival in order of magnitude: (1) patients found in ventricular fibrillation (odds ratio [OR] 5.3, 95% confidence limits [CL] 4.2-6.8), (2) the interval between call for and arrival of the ambulance less than or equal to the median (OR 3.6, 95% CL 2.9-4.6), (3) cardiac arrest occurred outside the home (OR 2.2, 95% CL 1.9-2.7), (4) cardiac arrest was witnessed (OR 2.0, 95% CL 1.6-2.7), (5) bystanders performing CPR before the arrival of the ambulance (OR 2.0, 95% CL 1.7-2.4), and (6) age less than or equal to the median (OR 1.6, 95% CL 1.4-2.0). When none of these factors were present, survival to 1 m was 0.4%; when all factors were present, survival was 23.8%. CONCLUSION: Among patients suffering from an out-of-hospital cardiac arrest, which were not crew witnessed, in Sweden and in whom CPR was attempted, 6 factors for an increased chance of survival could be defined. These include (1) initial rhythm, (2) delay to arrival of the rescue team, (3) place of arrest, (4) witnessed status, (5) bystander CPR, and (6) age.

Changes in demographic factors and mortality after out-of-hospital cardiac arrest in Sweden.

OBJECTIVE: To describe changes between 1992 and 2003 in age, sex, factors at resuscitation and survival among patients suffering from out-of-hospital cardiac arrest in Sweden. METHODS: This was a prospective observational study including various ambulance organizations in Sweden. Patients suffering from out-of-hospital cardiac arrest between 1992 and 2003 included in the Swedish Cardiac Arrest Registry were followed for survival to 1 month. RESULTS: In all 19 791 cases took part in the survey. There was a slight increase in mean age from 68 to 70 years (P = 0.025) and an increase of females from 29 to 32% (P = 0.0001). There was a change in witnessed status (P < 0.0001) with an increase in crew-witnessed cases and a decrease in non-witnessed cases. There was a decrease in cases of a cardiac etiology from 75 to 61% (P < 0.0001) and a decrease in the percentage found in ventricular fibrillation from 36 to 25% (P < 0.0001). When crew-witnessed cases were excluded the proportion receiving bystander cardiopulmonary resuscitation (CPR) increased from 30 to 42% (P < 0.0001). There was a slight increase in the overall proportion of patients hospitalized alive from 16 to 20% (P = 0.032). There was no significant change in the overall proportion of survivors at 1 month after cardiac arrest (4.5% in 1992 and 5.0% in 2003). CONCLUSIONS: Among patients suffering from out-of-hospital cardiac arrest in Sweden some changes took place. The most important ones were a decrease in the proportion of patients found in ventricular fibrillation and an increase in the proportion of patients receiving bystander CPR. The proportion of patients admitted alive to hospital increased moderately, whereas the proportion of patients alive after 1 month remained unchanged.

Decrease in the occurrence of ventricular fibrillation as the initially observed arrhythmia after out-of-hospital cardiac arrest during 11 years in Sweden.

AIM: To describe the change in the occurrence of ventricular fibrillation as initially observed arrhythmia among patients suffering from out-of-hospital cardiac arrest in Sweden. PATIENTS: All patients included in the Swedish cardiac arrest registry between 1991 until 2001. The registry covers 85% of the population in Sweden. METHODS: All patients with bystander witnessed out-of-hospital cardiac arrest included in the Swedish Cardiac Arrest Registry between 1991 and 2001 from the same ambulance organisation each year were included in the survey. RESULTS: Over 11 years, among patients in Sweden with a bystander witnessed out-of-hospital cardiac arrest in whom cardiopulmonary resuscitation (CPR) was attempted (n = 9666), the occurrence of ventricular fibrillation as the initially obseved arrhythmia decreased from 45% in 1991 to 28% in 2001 (P < 0.0001) if the arrest occurred at home, and from 57% to 41% if the arrest occurred outside home (P < 0.0001). This was found despite the fact that the proportion who received bystander CPR increased from 29% in 1991 to 39% in 2001 if the arrest occurred at home (P < 0.0001) and from 54% to 60% if the arrest occurred outside home (NS). There was a significant increase in age among patients with out-of-hospital cardiac arrest at home, no change in the estimated interval between collapse and call but an increase in the interval between call and arrival of the ambulance among patients with out-of-hospital cardiac arrest outside home. CONCLUSION: During 11 years in Sweden, there was a marked decrease in the proportion of patients found in ventricular fibrillation among patients with a bystander witnessed cardiac arrest regardless whether the arrest occurred at home or outside home. A modest increase in age and interval between call for, and arrival of, the ambulance was associated with these findings.

Is female sex associated with increased survival after out-of-hospital cardiac arrest?

AIM: To evaluate survival after out-of-hospital cardiac arrest in relation to sex. METHODS: All patients with out-of-hospital cardiac arrest included in the Swedish Cardiac Arrest Registry between 1990 and 2000 in whom cardiopulmonary resuscitation (CPR) was attempted and who did not have a crew witnessed arrest were included. The registry covers 85% of the inhabitants of Sweden (approximately 8 million inhabitants). P-values were adjusted to differences in age. Survival was defined as patients being hospitalised alive and being alive one month after cardiac arrest. In all, 23,797 patients participated in the survey of which 27.9% were women. RESULTS: Among women 16.4% were hospitalised alive versus 13.2% among men ( P<0.001). After one month 3.0% among women were alive versus 3.4% among men (NS). In a multivariate analysis considering differences in age and various factors at resuscitation female sex was an independent predictor for patients being hospitalised alive (odds ratio 1.66; 95% confidence limits 1.49-1.84) and for being alive after one month (odds ratio 1.27; 95% confidence limits 1.03-1.56). Women differed from men as they were older ( P<0.001 ), had a lower prevalence of witnessed cardiac arrest ( P=0.01), a lower occurrence of bystander CPR (P<0.001), a lower occurrence of ventricular fibrillation as initial arrhythmia (P<0.001) and a lower occurrence of cardiac disease judged to be the cause of cardiac arrest ( P<0.0001 ). On the other hand they had a cardiac arrest at home more frequently ( P<0.001 ). CONCLUSION: Among patients suffering out-of-hospital cardiac arrest in Sweden which was not crew witnessed and in whom resuscitation efforts were attempted, female sex was associated with an increased survival.

A short delay from out of hospital cardiac arrest to call for ambulance increases survival.

AIM: To describe the relative impact on survival of the delay from estimated time of collapse to call for an ambulance among patients who suffer from a bystander witnessed out of hospital cardiac arrest of a cardiac aetiology. METHODS: A majority of all ambulance organizations in Sweden (covering 85% of Sweden inhabitants) participate in a National survey of out of hospital cardiac arrest. RESULTS: In all there were 9340 patients with a bystander witnessed cardiac arrest of a cardiac aetiology in whom cardiopulmonary resuscitation (CPR) was attempted participating in this survey. Survival at one month among patients with a delay between estimated time of collapse and call for ambulance of < or =4 min (median) was 6.9% versus 2.8% among patients with a median of >4 min (P<0.0001). When adjusting for age, sex, initial rhythm, estimated interval between collapse and start of CPR, place of arrest and the interval between call for ambulance and arrival of the rescue team, the odds ratio for survival was 0.70 (0.95% CI. 0.58-0.84) per unit increase of the natural logarithm of delay in minutes between collapse and call. CONCLUSION: Among patients with a bystander witnessed out of hospital cardiac arrest of a cardiac aetiology increased delay from estimated time of collapse to call for an ambulance decreased the chance of survival.