Morphologic determinants of asphyxia in lungs: a semiquantitative study in forensic autopsies

Lung densitometry in postmortem computed tomography - comparison across different fatal asphyxia groups

Asphyxia as a cause of death poses a diagnostic challenge in forensic medicine due to both the diversity of underlying mechanisms, and lack of specific markers. Acute emphysema or acute alveolar dilation have long been debated as potential findings in these asphyxia cases. To further explore the supplementary findings in our forensic asphyxia cases, this study applied lung densitometry to pulmonary postmortem computed tomography (PMCT) data. Twenty asphyxia cases (including hanging (n = 9), manual strangulation (n = 4), ligature strangulation (n = 1), smothering (n = 3), and choking (n = 3)) and 21 matched control cases were analysed using lung densitometry parameters - specifically quantification of low attenuation areas (LAA) and the 15th percentile point of lung density (Perc15). Our data revealed statistically significantly higher lung % volume falling within LAA at -950HU (p = 0.04) and - 910HU (p = 0.043) in the asphyxia cases compared to matched controls. The Perc15 values observed were trending towards a lower attenuation corresponding to a lower density in the asphyxia group, although this result was not statistically significant (p = 0.13). A subgroup analysis highlighted potential differences within the asphyxia categories, notably, higher Perc15 values were observed in the choking cases. In conclusion the results from the study support the existing evidence of low pulmonary density as a potential finding in asphyxia cases and demonstrate the potential of applying lung densitometry on pulmonary postmortem computed tomography data.

Pulmonary barotrauma in SCUBA diving-related fatalities: a histological and histomorphometric analysis

Arterial gas embolism following pulmonary barotrauma occurs in 13-24% of cases of diving deaths. The study aimed to evaluate the usefulness of a histomorphometric digital analysis in the detection of air space over-distension due to pulmonary barotrauma. The study was performed on lung parenchyma specimens of 12 divers: six had died due to arterial gas embolism following pulmonary barotrauma (mean age at death of 54 years, range of 41-61 years), and six had drowned in saltwater without a diagnosis of pulmonary barotrauma (mean age at death of 54 years, range of 41-66 years) (positive controls). For negative controls, six cases of non-SCUBA divers (mean age of death of 42 years, range of 23-55 years) who died of intracerebral haemorrhage were evaluated. No significant differences were observed in the characteristics of the air spaces between control groups (positive and negative). However, differences were observed in the area occupied by air spaces and the percentage of air space area when we compared the case group to the controls (p < 0.01); and there was a slight difference in the maximum and minimum diameters of air space (p < 0.05). The mean area occupied by air spaces and the mean percentage of air space were the most useful for discriminating pulmonary barotrauma from other causes of death (100% sensitivity and 91.7% specificity). Based on our study, inclusion of an increased pattern of air spaces as a possible diagnostic criterion for pulmonary barotrauma would be useful in discerning the cause of diving death.

Hospital Restraints: Safe or Dangerous? A Case of Hospital Death Due to Asphyxia from the Use of Mechanical Restraints

Asphyxia can be defined as an impediment to the influx of air into the respiratory tract, leading to tissue hypoxia. By restraint, we mean the use of physical, pharmacological and/or environmental means to limit the subject's ability to move. Fall prevention is the main reason restraint is used. Unfortunately, restraint can sometimes be fatal. There are few studies in the literature on this subject. We report the case of a man with Down syndrome in a psychiatric clinic found dead between the bed and the floor of the room where he was hospitalized. The analysis of the scene showed the presence of a means of a restraint, located around the man's chest and neck, which kept him tied to the bed and applied a constricting mechanical action. There was doubt as to the cause of death. For this reason, an inspection of the scene and an autopsy were carried out. Upon opening the chest, blood infiltration of the left intercostal muscles that was topographically compatible with external cutaneous excoriation (sign of restraint) became evident. In view of the danger of using restraint, it is necessary to evaluate the means of restraint as an extraordinary and not an ordinary procedure in patient management. Each patient undergoing restraint measures must be carefully monitored by specialized personnel. Greater surveillance of the nurse/patient ratio is necessary to reduce the use of restraints. In this case report, we highlight the lack of surveillance of patients subjected to restraint.

Cases of asphyxia in children and adolescents: a retrospective analysis of fatal accidents, suicides, and homicides from 1998 to 2017 in Hamburg, Germany

PURPOSE

Injury-related asphyxia is one of the most common causes of death in children in Germany. However, only a few systematic studies have analyzed the causes and circumstances of asphyxia in children and adolescents.

METHODS

All cases of asphyxia in children and adolescents (0-21 years of age) among the Hamburg Legal Medical Department's autopsy cases from 1998 to 2017 were retrospectively analyzed with special focus on how often external findings were completely absent.

RESULTS

Among 249 cases of fatal asphyxia, 68% were accidents, 14% were suicides, and 13% were homicides. Most of the cases involved boys. Adolescents and young adults aged 15-21 years represented the main age group. Drowning was the leading mechanism of asphyxia. Younger age was associated with less frequent detection of external signs of asphyxia in the postmortem external examination. Petechial hemorrhages were the most common visible external indication of asphyxia. No external findings indicative of asphyxia were present in 14% of the cases.

CONCLUSION

Asphyxia in children and adolescents often involves accidents. However, postmortem external examination alone is insufficient to identify asphyxia and the manner of death.

A comparative digital morphometric study of lung tissue in saltwater and freshwater drowning

Acute pulmonary emphysema (APE) is describedin cases of drowning and can be considered as a sign of vitality. In our experience, however, APE is not very evident in cases of saltwater drowning. The present study aims at investigating whether APE is present in both fresh and saltwater drowning by means of digital morphometric analysis of lung tissue. We investigated and compared a group of saltwater drowning and a group of freshwater drowning, while cases of acute external bleeding were investigated as negative control group. Tissue samples from each pulmonary lobe were collected during autopsy and examined by optical microscope. The area of alveolar spaces was calculated by means of image analysis software, recording the mean alveolar area (MAA) for each group. MAA was 24,852 μm² in the saltwater drowning group, 34,133 μm² in the freshwater drowning group and 21,871 μm² in the negative control group. The MAA in freshwater drowning was significantly higher than in saltwater drowning and controls. No statistical differences were observed between saltwater drowning and controls. The results of this study suggest that APE is not a typical sign of death by saltwater drowning.

A Retrospective Study of the Investigation of Homicidal Childhood Asphyxial Deaths

As one of the leading causes of traumatic deaths in newborns, infants, and young children, there is no anatomic or microscopic feature that is pathognomonic for asphyxial deaths. Instead, pathologists rely on investigation information, including confessions and/or witness statements, and potential evidence at the scene. Twenty cases of homicidal newborn, infant, and young children asphyxial deaths were reviewed, which included death and police investigation reports and autopsy reports, as well as histology slides of lung sections. This series of homicidal asphyxial deaths highlight that, in a vast majority of such cases, the final cause and manner of death rulings are dependent on confession by the perpetrator. Furthermore, this series highlights the possible role of histology to help forensic pathologists better certify asphyxial deaths. Finally, this series emphasizes important investigation points and considerations at autopsy during the investigation of asphyxial deaths in newborns, infants, and young children.

Comprehensive Histological and Immunochemical Forensic Studies in Deaths Occurring in Custody

In-custody deaths have several causes, and these include homicide, suicide, natural death from chronic diseases, and unexplained death possibly related to acute stress, asphyxia, excited delirium, and drug intoxication. In some instances, these deaths are attributed to undefined accidents and natural causes even though there is no obvious natural cause apparent after investigation. Understanding these deaths requires a comprehensive investigation, including documentation of circumstances surrounding the death, review of past medical history, drug and toxicology screens, and a forensic autopsy. These autopsies may not always clearly explain the death and reveal only nonspecific terminal events, such as pulmonary edema or cerebral edema. There are useful histologic and biochemical signatures which identify asphyxia, stress cardiomyopathy, and excited delirium. Identifying these causes of death requires semiquantitative morphologic and biochemical studies. We have reviewed recent Bureau of Justice Statistics on in-custody death, case series, and morphological and biochemical studies relevant to asphyxia, stress cardiomyopathy, and excited delirium and have summarized this information. We suggest that regional centers should manage the investigation of these deaths to provide more comprehensive studies and to enhance the expertise of forensic pathologists who would routinely manage potentially complex and difficult cases.

Nondrowning Asphyxia in Veterinary Forensic Pathology: Suffocation, Strangulation, and Mechanical Asphyxia

Asphyxia in a forensic context refers to death by rapid cerebral anoxia or hypoxia due to accidental or nonaccidental injury. Death due to nondrowning asphyxia can occur with strangulation, suffocation, and mechanical asphyxia, each of which is categorized based on the mechanism of injury. Individuals dying due to various types of asphyxia may or may not have lesions, and even those lesions that are present may be due to other causes. The interpretation or opinion that death was due to asphyxia requires definitive and compelling evidence from the postmortem examination, death scene, and/or history. Beyond the postmortem examination, pathologists may be faced with questions of forensic importance that revolve around the behavioral and physiological responses in animals subjected to strangulation, suffocation, or mechanical asphyxia to determine if the animal suffered. While there is no prescriptive answer to these questions, it is apparent that, because of physiological and anatomical differences between humans and animals, for some mechanisms of asphyxia, consciousness is maintained for longer periods and the onset of death is later in animals than that described for people. Veterinary pathologists must be cognizant that direct extrapolation from the medical forensic literature to animals may be incorrect. This article reviews the terminology, classification, mechanisms, and lesions associated with asphyxial deaths in companion animals and highlights significant comparative differences of the response to various types of asphyxia in animals and people.

Pathological findings in wild harvested dugongs Dugong dugon of central Torres Strait, Australia

The dugong Dugong dugon is classified as Vulnerable to extinction but may be endangered in some regions. Cause of death in stranded dugongs has not been determined in a large proportion of animals examined, with investigations hindered by limited information on dugong health and diseases, and paucity of knowledge of common or endemic pathological findings. Here we describe pathological findings in harvested dugongs from the relatively pristine area of central Torres Strait, and we characterise lesions attributable to drowning. Other recorded lesions were mild and predominated by host reaction to the presence of trematodes within the gastrointestinal tracts, liver and pancreas. Ascarid worm burdens were low in comparison to dugongs from developed coastlines. Hepatocellular lipofuscin and ferritin pigmentation were commonly observed, more pronounced in livers of older animals and concurrent with periportal and bridging fibrosis. Lesions attributable to drowning included incomplete collapse of lungs, dorsal or diffuse pulmonary congestion, mild intra-alveolar haemorrhage and oedema, mild interstitial oedema and rupture of peripheral alveolar septae with acute myofibre fragmentation and degeneration. No accumulation of foam or aspiration of water or particulate matter was observed, suggesting that dugongs 'dry drown'. Morphometric features of normal spleen are also presented. Characterisation of common pathological findings and those attributable to drowning in this species will aid in the interpretation of post mortem findings for the significant number of dugongs found deceased along urbanised coastlines.

Detection of diatoms in water and tissues by combination of microwave digestion, vacuum filtration and scanning electron microscopy

The detection of diatoms has been proposed to be useful in the diagnosis of drowning. In the presented paper, we describe a novel method for qualitative and quantitative analysis of diatoms in water and organs. Samples were treated by microwave digestion. The fluid obtained was vacuum-filtrated; its sediment on the membrane was coated and examined under the scanning electron microscope with the mode of automatic field scanning; and qualitative and quantitative diatom analysis was performed based on the images captured automatically and on manual identification of the suspected diatoms at a required higher magnification. The method is rapid, sensitive, labor-saving, and accurate for qualitative and quantitative diatom analysis. However, further scientific research in the field of automatic diatom identification using SEM images has to be done in order to automate the process of detection and identification of diatoms in water and tissues for the diagnosis of drowning.

Is acute alveolar dilation an indicator of strangulation homicide?

Some cases of suspected homicidal strangulation are difficult to diagnose if the classical injuries of strangulation are few or lacking. The main purpose of this study was to determine if abnormal distension of alveolar airspaces is present in strangulation deaths and whether or not it can be used to support this diagnosis. Another purpose was to see how often the gross examination of the lungs was in agreement with the microscopic examination. The material comprised 33 victims of homicidal strangulation above the age of 15 years, autopsied at the Department of Forensic Medicine in Copenhagen between 1998 and 2007. The results were compared with a control group of the same size, matched for gender and age, all of whom died naturally of cerebral or other neurological causes. The autopsy reports provided the results of the gross examination of the lungs. Regular haematoxylin-eosin stained sections were made from the histological specimens. The microscopic examination was performed by computerized image analysis using stereological methods in an attempt to objectify the observations. The results showed an almost complete concordance between the findings of the gross and the microscopic examination. Stereologically the study showed that the alveoli in the strangulation cases were twice the size of those in the control group which was highly statistically significant concluding that abnormal distension of alveolar airspaces.

Morphometric investigation of death by asphyxia

The aim of this study was to investigate the possibility of distinguishing deaths by asphyxia from those due to natural causes by comparing morphometric measurements in lungs. The study population comprised 27 subjects: 14 cases of death by asphyxia (hanging or drowning) and 13 cases of sudden natural death. Eighty parenchyma sections were used for each subject. Data were collected by computerized image analysis. Measurements aimed at quantifying, as percentages, pulmonary parenchyma (mean values of positive-fraction areas [PFA] and their standard deviations). Subjects who died of natural causes and of drowning showed a relative internal homogeneity compared to those who hanged. Results show significant discrimination between drowned subjects and those dying of natural causes (mean of PFA p = 0.01) and between hanged and drowned subjects (SD of PFA p = 0.04). Attention must be paid to the possible role played by senile emphysema. The method is proposed as a complementary tool in forensic cases.

Autopsy-proven determinants of immediate fire death in lungs

In immediate fire deaths, pulmonary injury may be the main source of mortality, being important to document the histologic findings for the purpose of excluding other modes of death, such as from asphyxia with no gross findings. In this context, a group of morphologic determinants have been targeted with useful makers of pulmonary injury. To facilitate the determination of whether an individual was deceased before the start of a fire and validate the importance of parenchymal alterations in pulmonary injury in fire deaths, we studied lungs in victims of fire (N = 28) and suffocation (N = 40), creating a mathematical model using cluster analysis. For this purpose, a semiquantitative analysis of the distal parenchyma was performed to evaluate the amount of bronchiolar dilatation, overinsufflation (ductal and alveolar), collapse (ductal and alveolar), passive congestion, alveolar edema, and hemorrhage (interstitial and alveolar). These 7 histologic determinants were useful to discriminate fire (bronchiolar dilatation, ductal overinsuflation, alveolar overinsuflation, alveolar hemorrhage) from suffocation lung injuries (alveolar collapse, congestion, and edema). We conclude that these determinants should be included in the routine of forensic pathology.

A prediction score model for risk factors of mortality in neonate with pulmonary hemorrhage: the experience of single neonatal intensive care unit in Southwest China

AIM

To establish a prediction score model for mortality of neonates with pulmonary hemorrhage (PH).

METHODS

Mortality risk factors of PH were analyzed by logistic regression analysis in 244 neonates retrospectively. A prediction score model was developed according to regression coefficients of risk factors. The receiver operating characteristic curve (ROC) was also constructed and the cutoff was determined.

RESULTS

The overall mortality rate of PH was 74.59% (182/244). More patients from multiple pregnancies were found in the death group than in the survivor group (20.1% vs. 3.2%, P = 0.023). The survivor group infants had higher birth weight in average than death group infants (2,787 g vs. 2,339 g, P = 0.000). Significant differences were found between survivor and death groups in the rates of intraventricular hemorrhage (IVH) (25.8% vs. 53.8%, P = 0.000), heart failure (22.6% vs. 48.9%, P = 0.000) and sepsis (3.2% vs. 16.5%, P = 0.008). Birth weight, IVH, heart failure and sepsis were identified as independent mortality risk factors by logistic regression analysis. A score model predicting death was developed according to the regression coefficients, with a sensitivity of 0.846, a specificity of 0.661, a positive predictive value of 0.88 and a negative predictive value of 0.594 at a cutoff of 9 points. The low risk group, with a score of 9 or less, had a lower mortality rate as compared with the high risk group (40.6% vs. 88%, P = 0.000).

CONCLUSIONS

Low birth weight, IVH, heart failure and sepsis were the risk factors for mortality of PH. Those infants with a predictive score of more than 9 were at high risk for death.

Asphyxial Deaths

An increasing death rate as a result of violence constitutes a large group in medicolegal autopsies. Specially, deaths due to asphyxia are one of the most important causes in violence deaths. During the 21-year period from January 1984 to October 2004, there were 134 asphyxial deaths autopsied by the Department of Forensic Medicine, Trakya University, Edirne, Turkey. Asphyxial deaths comprise 15.7% of all forensic autopsies; 20.8% of the cases are aged between 30 and 39 years, and the average age was 41.9 years. Males constitute 79.8% of all the cases. The most frequent method of asphyxiation death is hanging (56 cases, 41.8%), followed by drowning (30.5%) and carbon monoxide poisoning (8.2%). More violent methods, such as ligature or manual strangulations, constitute 2.9% and 2.3% of all asphyxial deaths, respectively. Although it was varying according to the methods of asphyxiation, suicide was found to be the manner of death in the majority of the cases.

Drowning: still a difficult autopsy diagnosis

Investigation of bodies recovered out of water comprises an important proportion of the medico-legal requests. However, the key question whether the victim died due to "true" drowning can frequently not easily be solved. In addition, the diagnosis of hydrocution is even more difficult. In this manuscript, a review of reported diagnostic methods is discussed in order to provide guidelines, which can be used in current forensic practice. In particular, the (dis)advantages of various biological and thanato-chemical methods, described in literature during the last 20 years, will be confronted with the classical techniques such as the detection of diatoms and algae. Indeed, the diatom test is still considered as the "golden standard". In conclusion, the ideal diagnostic test as definite proof for drowning still needs to be established. At present, the combination of the autopsy findings and the diatom test is a good compromise in arriving at a conclusion. Additional biochemical and technical methods could be useful. Unfortunately, the cost-benefit analysis in current practice could be hard to defend. However, the importance of this subject asks for further scientific approaches and research.

Childhood foreign body aspiration in Istanbul, Turkey

In this study, we present the data concerning 10 children (six boys, four girls) with a diagnosis of foreign body aspiration (FBA) amongst 19,951 cases that underwent autopsy between the years 1996-2002. Eight of the children were under 2 years old. All the incidents took place at home. One of the parents was in the company of the child at the time of incident. At least one of the risk factors was positive. Interestingly, all of the aspirated material was related to food except one. Only four cases had subpleural petechiae, whereas five of the seven subjects undergoing histopathological evaluation had edema, hyperemia or intra-alveolar fresh bleeding. The legal instructions, which regulate the standards of toy materials, came into force at the end of 2003. Even though the legal instructions regulating the size and consistency of toys are very important to prevent FBA, we believe that the education of the parents and carers in the prevention of food aspiration is of greater importance.

SIDS pathogenesis: pathological findings indicate infection and inflammatory responses are involved

This article explores the pathological evidence that supports the hypothesis that infection and inflammation are underlying mechanisms in SIDS. It reviews the pathological findings in relation to the risk factors reported for SIDS and compares these findings with other hypotheses suggested as causes of these unexplained deaths in infants. The roles of environmental factors and bacterial products such as soluble curlin detectable in SIDS sera in triggering cytokine cascades and aberrant inflammatory responses resulting in a toxic shock-like event are also explored. Areas for future research are outlined.

Sudden infant death syndrome: a critical review of approaches to research

This review explores the various research approaches taken attempting to solve the problem of SIDS. It would appear that major clues provided by pathological findings have been largely overlooked and as a consequence much effort, time, and money has been wasted on projects that satisfy only sub-specialty and political needs. Close examination of the pathological clues would provide better insights into the mechanisms underlying this enigmatic and heartbreaking problem.

Drowning and near-drowning

Water immersion is a frequent cause of accidental death and hospital admission. This article outlines the pathogenesis and principles of treatment. Drowning is defined as death by asphyxia due to submersion in a liquid medium. Near-drowning is defined as immediate survival after asphyxia due to submersion.