Search

Background Increased airway smooth muscle is observed in large and small airways in asthma. Semi-quantitative estimates suggest that cells containing alpha smooth muscle actin (α-SMA) are also increased in the lung parenchyma. This study quantified and characterized α-SMA positive cells (α-SMA+) in the lung parenchyma of non-asthmatic and asthmatic individuals. Methods Post-mortem sections of peripheral lung from cases of fatal asthma (FA), persons with asthma dying of non-respiratory causes (NFA) and non-asthma control subjects (NAC) were stained for α-SMA, quantified using point-counting and normalised to alveolar basement membrane length and interstitial area. Results α-SMA+ fractional area was increased in alveolar parenchyma in both FA (14.7 ± 2.8% of tissue area) and NFA (13.0 ± 1.2%), compared with NAC (7.4 ± 2.4%), p < 0.05 The difference was greater in upper lobes compared with lower lobes (p < 0.01) in both asthma groups. Similar changes were observed in alveolar ducts and alveolar walls. The electron microscopic features of the α-SMA+ cells were characteristic of myofibroblasts. Conclusions We conclude that in asthma there is a marked increase in α-SMA+ myofibroblasts in the lung parenchyma. The physiologic consequences of this increase are unknown.

Background: Avalanches are a significant cause of winter recreational fatalities in mountain regions. The purpose of this study was to determine the relative contributions of trauma and asphyxia to avalanche deaths. Methods: We reviewed all avalanche fatalities between 1984 and 2005 that had been investigated by the offices of the British Columbia Coroners Service and the Chief Medical Examiner of Alberta. In addition, we searched the database of the Canadian Avalanche Centre for fatal avalanche details. We calculated injury severity scores for all victims who underwent autopsy. Results: There were 204 avalanche fatalities with mortality information over the 21-year study period. Of these, 117 victims underwent autopsy, and 87 underwent forensic external examination. Asphyxia caused 154 (75%) deaths. Trauma caused 48 (24%) deaths, with the rate of death from trauma ranging from 9% (4/44) for snowmobilers to 42% (5/12) for ice climbers. In addition, 13% (12/92) of the asphyxia victims who underwent autopsy had major trauma, defined as an injury severity score of greater than 15. Only 48% (23/48) of victims for whom trauma was the primary cause of death had been completely buried. Interpretation: Asphyxia and severe trauma caused most avalanche fatalities in western Canada. The relative rates differed between snowmobilers and those engaged in other mountain activities. Our findings should guide recommendations for safety devices, safety measures and resuscitation.

The bronchial arteries supply systemic blood to the airways, tracheobronchial lymph nodes, and nerves. Their structure has not been studied in patients with asthma.Case-control study of pathologic changes of bronchial arteries in asthma.Postmortem lungs were examined from three case groups: (1) fatal asthma (n = 12), death due to asthma; (2) nonfatal asthma (n = 12), asthmatic and death due to nonrespiratory causes; and (3) nonasthmatic control subjects (n = 12), no history of asthma and death due to nonrespiratory causes. In bronchial arteries with outer diameters of 0.1 to 1.0 mm, the areas of lumen, intima, and media were measured and compared between case groups.There were no significant differences in artery size (outer diameter) or in medial area between the three groups. In the two asthma groups, the intimal area was increased (p0.05), with a corresponding decrease in luminal area compared with the control group. There was a significant effect of gender, age, and smoking on intimal area. In the asthma cases, the area of bronchial artery intima was related to duration of asthma (p0.05), and this increase was associated with smooth muscle proliferation, reduplication, and calcification of the elastica, but not with inflammatory cell infiltration.While the pathophysiologic significance of these changes is uncertain, the relation to duration of asthma, age, and smoking suggests a secondary response to chronic airway disease.

A submucosal network of elastic fibers in a collagen and myofibroblast matrix form discrete longitudinal bundles (LB) in the bronchial tree. The LB may affect airway function by altering the mechanical properties of the airway wall or by changing the folding behavior of the airway mucosa. The area and number of LB were quantified from 12 cases each of fatal asthma (FA), nonfatal asthma (NF), and nonasthmatic (NA) control cases on elastic-trichrome stained airways. The effects of group, sex, age, and smoking were examined using multiple linear regression. The area fraction of LB increased (p < 0.05) approximately twofold in cases of FA compared with NA control cases in both large and small airways. The areas of LB were increased in smokers, older subjects, and men (p < 0.05). The number of mucosal folds was related to the number of longitudinal bundles in asthmatics and nonasthmatics and was not different between groups. Collagen and myofibroblasts were increased (p < 0.05) in LB of FA and NF cases compared with NA control cases. The increased size and altered composition of LB in asthma may influence airway function; however, excessive airway narrowing in asthma is not due to altered numbers of mucosal folds.

To evaluate risk factors for asthma mortality, an unmatched case-control study was undertaken in the Canadian prairie provinces of Alberta, Saskatchewan, and Manitoba. Those between the ages of 5 and 50 (inclusive) who died from an acute exacerbation of asthma were compared to a control group of people with asthma from the same geographical areas who were contacted using random-digit dialing. Because no deaths occurred among residents less than 15 years old, this analysis was limited to cases and controls between 15 and 50 years old. Of the 38 deaths that occurred between November 1992 and October 1995, data were obtained from next of kin for 35 (92.1%). Of the 210 potential controls that were identified, 142 returned completed questionnaires (67.6%). Cases were more likely than controls to have asthma reported to be severe, to have experienced nocturnal symptoms, to have had cardiopulmonary resuscitation (CPR)/intubation, and to have had more healthcare utilization in the previous year. Medication use was also more common among cases compared to controls. Specific asthma triggers were reported more often for cases than controls; weather changes, excitement, depression, and stress showed the greatest case control differences. Although a number of very strong risk factors for death from asthma were identified, death from asthma is so rare in this age group that it is not possible to label an individual as "likely" to die from asthma. Nonetheless, patients, caregivers, and health professionals should be aware of indicators that would suggest greater risk.

To identify factors that may contribute to asthma mortality, 108 acute asthma deaths were reviewed. Information was obtained from medical records, next-of-kin, and autopsy records. The fatal asthmatic was characterized by early-onset asthma, severe disease requiring systemic corticosteroids, and prior hospitalization. Risk factors associated with gender, season, employment, and region were also identified. The fatal attack was characterized by an identifiable trigger, delay in seeking medical attention, and rapid deterioration in clinical status. Death due to asthma was confirmed in 95% of autopsied cases. Adrenal cortical abnormalities were recorded for 18.7% of cases. We conclude that, in addition to established risk factors, complications associated with the use of systemic steroids may contribute to the risk for sudden death in this age group.

Reviewed here are those circumstances surrounding 18 downhill skiing deaths in Alberta, Canada. Variables that elevate the risk of injury and death are highlighted. This study profiles the fatally injured skier. The individual most likely to die while downhill skiing is an experienced male skier, average age 31 years. He loses control while skiing too fast and strikes an object, resulting in fatal blunt trauma injuries. The ability to define characteristics of the individual at risk of a fatal ski injury is important to the design and implementation of injury prevention programs. Public education targeted to those at risk may reduce the incidence of death and injury in downhill skiing. Language: en

Occasionally, encounters with a grizzly or a black bear have proved fatal. We describe the characteristics of fatal bear maulings and the circumstances that provoked them. The actions of wild bears are compared with those of bears that have become comfortable around people (wild/"habituated" bears). A description of eight deaths that occurred in the province of Alberta, Canada, between 1973 and 1988 will underscore the above.

Sera were obtained postmortem from 55 subjects classified into three groups; death due to asthma (FA, n = 21), asthmatic but death not due to asthma (NFA, n = 24) and a nonasthmatic control group (NAC, n = 10). A full autopsy was performed on all cases and a medical history, including details of allergies, was obtained by questionnaire from the next of kin. Grading of asthma severity by either questionnaire or autopsy was comparable (tP = 0.435, p0.05) and the mean pathology-grade was significantly higher for the FA group (3.375) compared to the NFA group (2.375), p0.05. Tryptase was elevated (2.0 micrograms/L) in 21/55 sera (38%) and there was no significant difference between the groups. ROC plots showed that tryptase levels did not discriminate between the FA and NFA groups, even if specimens were collected within 24 hours after death. Total IgE was significantly elevated in the FA group (geometric mean 140.3 kU/L) compared to the other two groups (NFA 30.2 kU/L, NAC 9.4 kU/L), p = 0.05. Fatal asthmatics also had a greater positivity (67%) to a screen for common inhalant allergens than did the other groups (NFA 30%, NAC 20%). Sera with a positive screen were tested against a panel of 10 common aero-allergens. Each sample was then assigned a number (N) and a score (S), dependent on either the number of allergens positive (N) or the total sum of pluses for all allergens (S). Both the N and S values were higher for the FA group (N = 98, S = 264) than the NFA group (N = 52, S = 151) and NAC group (N = 4, S = 8). The ratio (S/N) which gives an index (I) was 2.69, 2.90, and 2.00, respectively. Tryptase was poorly correlated to the total IgE level (r = 0.036); however, mean values for N and S were significantly different (N 6.81, S 4.50, and N 19.25, S 11.5, p0.05) for sera with tryptase levels2.0 oror = 2.0 micrograms/L, respectively. We conclude that total and specific IgE may be useful predictors of asthma severity but that postmortem tryptase is not useful in the diagnosis of a fatal asthmatic attack.

This paper presents an unusual form of sexual (masturbatory) activity and brings this unusual cause of death to wider medical attention and understanding. All 19 cases of auto-erotic asphyxial death that occurred between 1978 and 1989 in the province of Alberta, Canada were reviewed. The fatal victim of auto-erotic asphyxia is typically a single male aged 15 to 29 years. Autoerotic sexual activity is typically performed in isolation; often there is evidence of repetitive practice. The accidental death usually results when the “safety” mechanism designed to alleviate neck compression fails. Often the first sign of the activity (usually a surprise to family and friends) is death itself. Physicians who are alert to the practice may suggest counselling when patients present with sexual concerns, unusual marks around the neck or evidence of abrasions to limbs suggesting bondage or other masochistic practices.

An historic case of a boxing death (c. 1913) was reviewed, since the cause of death given at the time is now deemed incorrect. Using current literature on traumatic basal subarachnoid hemorrhage, the cause of death is now hypothesized to have been a tear in the right vertebral artery associated with hyperextension and rotation of the neck.

A review of circumstances surrounding 19 backcountry deaths in Alberta, Canada, between 1980 and 1991 suggests several factors that increase the risk of injury or death. This study provides a descriptive profile of a fatally injured backcountry skier and the circumstances surrounding his or her death. The individual most likely to suffer a fatal injury while participating in a backcountry ski activity is a 36-year-old man. He is typically an experienced backcountry skier who chooses to ski in areas where the avalanche hazard is known to be moderate to extreme. Delineating the personal characteristics of those at risk for backcountry injury and identifying situations that put them at risk will enable better design of education programs. Targeting high-risk groups may also reduce the incidence of death from this activity. Language: en

A case of fatal cardiac tamponade due to myxedema pericarditis is reported. The woman, a 54-year-old Christian Scientist, had never sought medical care and died at home. The pericardial sac occupied most of the thorax and contained 2,270 mL of fluid. A thick, shaggy, fibrinous exudate on the pericardium contained abundant cholesterol clefts typical of chronic effusion and myxedema. Thyroid function tests on postmortem blood revealed pro-found hypothyroidism, and the thyroid was atrophied, with the histologic appearance of primary atrophic thyroiditis. Pericardial effusion is common in myxedema, but cardiac tamponade is rare, only 13 cases being previously reported, none of which was fatal.