Pulmonary Autopsy Findings of the Rats Drowned at Surface and 50 Ft Depth
Critical Appraisal of a Research Article
Of the following literature that was examined, one of the most useful articles was entitled Pathology of the Lung in Near Drowning, a paper in which the researchers created an experimental model that simulated the changes that actually occurred in a subject which had nearly drowned. The purpose was to study the pathological changes that happen when someone or something is drowned. The methodology involved intubating rabbits in either salt or fresh water, and microscopically examining their lungs and hearts. The results indicated that within the first 30 minutes after being drowned, the vast majority of damage does not occur in the alveolar cells but in the vascular endothelium (Karch, S.B, 1986).
The next piece of literature that was reviewed was called Alveolar Macrophages and the Diagnosis of Drowning, in which alveolar macrophages in lung tissue were studied in cases of drowning, acute death and lung emphysema. Examination of the alveolar macrophages revealed that there were decreased values in cases of drowning. The study hypothesized that partial removal of the alveoli macrophages could be explained by a "wash-out" effect of the fluid used for drowning, which was confirmed by an immunohistochemical examination that revealed their presence in the drowning froth.
Comparative Histopathology of Lungs from by-caught Atlantic White-Sided Dolphins was also studied. This research paper examined the histology of the lungs of dolphins and porpoises and compared them with findings from asphyxia and drowning of both humans and mammals. All of the findings revealed some degree of distension within the alveolar walls, while the porpoises' and dolphins' lungs had oedema and ruptures within their alveolar spaces (Knieriem, A., Garcia Hartmann, M., 2001). The study concluded that the histological changes occurring in the dolphins and porpoises were equivalent to those described as 'atypical drowning lung' in land mammals (including humans).
Additionally, A Method for Investigating Specialised Accidents with Special Reference to Diving was reviewed. This paper detailed an investigative process for investigating diving deaths caused by accidental complications. The study aimed to formulate a specific series of regulations which could be utilized to prevent future accidents of this variety, and focused on the importance of communication between legal, medical and technical personages to consolidate the factors which lead to these outcomes.
Lung Histology in Experimental Drowning is the name of a study in which researchers experimented on rats to gauge the histological effects within the lungs resulting from drowning. The influx of both saline and fresh water caused several reactions, one of the most salient of which was the development of edema in the alveolar and interstitial areas (B. Brinkmann, G. Fechner, K. Puschel, 1983). Significantly, the alveolar macrophages were increased to the point where there were ruptures of the alveolar walls and occurrences of hemorrhaging.
The research article which is being critiqued in this paper is entitled Comparison of pulmonary autopsy findings of the rats drowned at surface and 50 ft depth, which appeared in Forensic Science International's December 20, 2006 publication. The research project attempted to evaluate the physiological differences in drowning victims which occurred at the surface and in significantly deeper water with substantial pressurized conditions. The basic methodology used involved dividing a population of 45 rats into three groups, some of which were drowned at the surface level of water, some of which were drowned at the surface and then sunk to a depth of 50 feet, and others of which were drowned at a depth of 50 feet of water pressure. The essential hypothesis was that physiological differences would be detectable between the groups of rats that were drowned at the surface and those drowned in a water pressure which was substantially greater than that of their bodies.
Specifically, the research group believed that there would be highly palpable levels of mechanical damage to the lungs and their surrounding tissues for the latter grouping, due to the expansion of air attributed to Boyle's Gas Law which states that such expansion will occur due to an increase in environmental pressure. This hypothesis hinges upon the notion that the intake of air in a drowned subject at a significant depth will be equal to that existing air pressure (Toklu AS, Alkan N, Gurel A, Cimsit M, Haktanir D, Korpinar S, Purisa S, 2006). The actual results ascertained by this study indicated that there was a profound degree of swelling in the lungs and surrounding areas of the rats which were drowned at 50 feet of depth, which was not demonstrated in the lungs and surrounding areas of the other groups of rats. These results were integral to the conclusion of the authors that the examination of the swelling of lungs and parts of the body in close proximity to them can be instrumental in determining where a drowning death occurred, rendering pulmonary autopsies an essential component to the investigation of such deaths.
Although there are certainly areas for improvement in this article's presentation and the methodology employed by its researchers and their respective conclusions, there are a number of positives which can be drawn from those same methodologies and findings. The actual need for the study -- for determining at which point in or above water level in which a drowning death occurred -- is one which can be of immense use to forensics analysts as well as to criminal investigations, for the simple fact that this information can help ascertain a cause of death. The study acknowledges its practical purposes by stating that drowning deaths of self-contained underwater breathing apparatus (SCUBA) divers at highly pressurized depths of water levels have a higher propensity for being attributed to oxygen toxicity, equipment failure or panic, while those occurring closer to the surface are likely to be caused by external trauma, decompression sickness or previously existing medical conditions (Toklu AS, Alkan N, Gurel A, Cimsit M, Haktanir D, Korpinar S, Purisa S, 2006).
Another credible facet of the study can be seen in the fact that it chose to test a group of rats which had drowned at the surface and then sunk to a highly pressurized depth, which helps to distinguish this occurrence from that of those which drowned at a highly pressurized depth. Testing this group allows for the clarification of any potential misidentification for analysts and authority figures, and demonstrates that the effects of the lungs are differentiated between this group and those that were drowned at 50 feet of water pressure.
In terms of areas of this study which can be improved, the most eminent is the presentation of the writing which typifies the duration of the report. The numerous grammatical and idiomatic lapses greatly detract from the reading of the paper, and lend themselves to doubts as to the competence of the authors. Aside from the several instances of omissions of verbs and failures to properly pluralize nouns, there is more than one egregious instance of the researchers' lapse in prudent employment of methodology. One such example can be found in the time interval between the death of the rats and the autopsies performed on them, which the researchers state changed from 90 to 120 minutes and provides a variable which cannot be accounted for in the precision and accuracy of the findings. The relatively brief time interval also omits the relevance of the data and their conclusion in drowning deaths in which the deceased are found and given an autopsy for more than two hours after the subject's demise.
Additionally, the research in this particular area of interest was not wholly original and did replicate the findings of previous work in this area of forensics. A large part of the analytical process on which the results were based upon involved histological features; the very basis for the conclusion that rats drowned at high levels of water pressure had a significant difference (115 to 88) in the number of microscopic fields with a longitudinal dimension greater than 300 mm out of 150 fields hinges upon such features. Yet the researchers note in their discussion that the general histological features of all rats were in accordance to findings provided by a study from Brinkman et al. (Toklu AS, Alkan N, Gurel A, Cimsit M, Haktanir D, Korpinar S, Purisa S, 2006). Finally, it should be noted that there is room for ambiguity in the histological features results for rats drowned at the surface and then sunk and those drowned at 50 feet of water pressure, since the difference between their respective microscopic fields was just 101 to 115 and was not found to be statistically significant or part of the study's conclusion.
As to the future direction of this particular work in the field of forensic science, the obvious unanswered question would be how best to solidify the article's conclusion while accounting for the aforementioned histological features comparison of the results of the rats drowned at high levels of water pressure and those drowned…
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