Clinical and epidemiological aspects of victims of maritime accidents on the Mar Grande-Salvador crossing, Bahia, Brazil: a case series study

ABSTRACT BACKGROUND: Maritime transportation is an activity of vital importance for societies. The Mar Grande-Salvador crossing is an intercity waterway transport line in Brazil that transports 3,500 passengers/day, including residents and tourists. In 2017, an accident on this crossing was considered to be the biggest maritime tragedy in Bahia in the last decade. OBJECTIVE: To describe the clinical and epidemiology characteristics of victims of this maritime accident, with analysis on bodily injuries, causes of death and means/instruments that caused the fatal injuries. DESIGN AND SETTING: Case-series study at the Forensic Medical Institute of Bahia, Brazil. METHODS: Reports on 73 victims who were examined for bodily injury or were necropsied by the Forensic Medical Institute were analyzed. This study was approved by the institution’s Research Ethics Committee (protocol 04012218.1.0000.5032). RESULTS: The victims’ mean age was 33.0 years [95% confidence interval, CI, 26.3-47.0]. The mean age of those who died was 43.0 years [95% CI, 30.5-53.5]. Bodily injuries were found in 74% of the victims. The most frequent bodily injuries were ecchymoses among females (69.7%) and abrasions among males (76.2%). Blunt instruments produced most bodily injuries (85.2%). Among the victims who died, 68.4% were female. Mechanical asphyxiation through drowning was the leading cause of death (89.4%). The overall lethality rate was 26%, and this was higher among females (28.2%). CONCLUSION: Women were the main victims of this maritime accident. Bodily injuries occurred more frequently than death, but these injuries proved to be quite significant, thus demonstrating the importance of measures to improve the safety of navigation.

In Brazil, deaths due to drowning exceed 5,700 cases/year, and most of the victims are children. In 2016, about 89% of drownings in Brazil had unintentional causes. Of these, 1.1% were due to boating accidents. 9 Death due to drowning is a three-phase process: defense, resistance and exhaustion. The defense phase can be further divided into surprise and dyspnea. In the resistance phase, as a form of defense, breathing movements are interrupted. This is followed by the exhaustion phase, when resistance ceases and the victim starts breathing deeply and then loses consciousness and dies. 10 Individuals who survive the submersion episode may develop late complications resulting from water aspiration, such as severe infections and pulmonary edema, which may later result in the victim's death. 11 In accidents in fluvial or marine waters, when an unconscious person is found in shallow waters, it needs to be considered that spinal cord injury, head trauma or sudden illness may have occurred.
These can be caused by acute myocardial infarction, convulsion, lipothymia, hydrocution (thermal shock) or primary drowning in which the victim ends up in shallow waters. 12 Given that head trauma is responsible for 25% of trauma deaths, this should be evaluated among individuals who are victims of accidents involving water. 13 Maritime accidents can result not only in drowning, but also in other injuries to the human body. According to the Brazilian Penal Code, these may be classified as mild, serious or very serious, and may also involve intentional injuries. 14 From the medical-legal point of view, intentional injuries are consequences of a violent act that is capable of directly or indirectly producing damage to someone's physical integrity or health, or that is responsible for worsening or continuation of an already existing disturbance. These injuries therefore consist of alterations to the biopsychosocial balance. Violence should be understood not simply as the consequence of mechanical action, but as the means of action, whether physical, chemical, physicochemical, biochemical, biodynamic or mixed. 15 Given the large number of shipwrecks recorded over recent years and the need for research describing maritime accidents that occurred in Brazilian territory, it is relevant evaluate the possible causes of death and bodily injury among the victims. Drowning may or may not have been the ultimate cause. Thus, there is a need to assess whether drowning is, in fact, what kills the most during this type of accident. 16

OBJECTIVE
In this context, considering the proportions of this accident on the Mar Grande-Salvador crossing, the aim of the present study was to describe the clinical and epidemiological characteristics of the victims and to analyze their bodily injuries, the cause of death and the means or instrument of action that produced the fatal injuries. that produced the fatal injury or injuries; and (III) whether poison, fire, explosives, asphyxiation, torture or other insidious or cruel means were used, or the means resulted in common danger, or whether any means that made it difficult or impossible to defend the victim was used.

This
Data analysis was performed using the IBM SPSS software, version 26.0 (SPSS Inc., Chicago, Illinois, United States). Categorical variables were presented as the frequency distribution of the categories, represented as absolute numbers (n) and percentages (%).
Numerical variables were described as medians and 95% confidence levels. In addition, the lethality rate was calculated overall and according to sex.
Because this was a study involving human beings, it was sub-

RESULTS
An overview of the accident revealed that there was a total of 73 victims, who were all among the passengers on the vessel. The distribution of the victims with bodily injuries and deaths according to age and sex is shown in Table 1.
By stratifying them according to sex, it was observed that the women who suffered bodily injuries were older than the men Regarding the cause of death, it was observed that mechanical asphyxia due to drowning occurred in 89.4% of the deaths (n = 17). The remaining deaths occurred due to brain hemorrhage and mechanical asphyxia after head trauma (n = 1; 5.3%) and to an undetermined cause (n = 1; 5.3%).
From evaluating the instrument or means that produced the injury, it was found that a physical-chemical means was the main agent responsible for the deaths, totaling 84.2% of the cases (n = 16). A physical-chemical means in association with blunt instruments resulted in 10.5% of the deaths (n = 2). In 5.3% of the cases (n = 1), the analysis was impaired.
Considering the instruments or means that produced bodily injuries, the most prevalent type was blunt instruments, which accounted for 85.2% of the injuries produced (n = 46). Injuries caused by blunt/short blunt instruments and blunt instruments/ physical-chemical means accounted for 3.7% (n = 2) each.
Regarding the bodily injuries presented by the victims, it was observed that among women, ecchymoses were most prevalent, in 69.7% of the cases, followed by abrasions in 66.7% and contusion wounds in 24.2%. Unlike the results found among females, abrasions were the most prevalent injuries among males, totaling 76.2% of the cases, followed by ecchymoses in 38.1% and contusion in 19.0%. The other injuries presented are described in Table   2. It is important to note that combinations of different types of bodily injuries were present in some of in the accident victims.
In assessing the consequences of the injuries suffered by the victims, it was found that in 1.9% of the cases there was incapacity in relation to the usual occupations for more than 30 days, while 85.2% did not suffer any such incapacity. For 92.6% of the victims, their bodily injuries did not result in any life-threatening condition. In addition, 85.2% of the victims did not suffer any permanent weakness of limb or impairment of its sensation or function, or any acceleration of labor, while 13.0% relied on further examinations to find out whether the weakness would be permanent or not (Table 3).   Regarding the age of the fatal victims, only three children died in this accident: two were two years old and one was six months old.
Corroborating this finding, the study by Quan and Cummings,19 carried out between 1980 and 1995, showed that children between 0 and 4 years old, when alone, tend to drown when they fall into pools or open waters (rivers or lakes), while people between 35 and 64 years old are usually sailing when drowning occurs.
In the maritime accident that occurred on the Mar Grande-Salvador crossing, the main cause of death was mechanical asphyxiation through drowning. According to Armstrong and Erskine,20 drowning is considered, in most cases, to be an asphyxiating process that can cause systemic repercussions in several organs, and the lungs are certainly the organ most affected during this process. 7 As a consequence of the obstruction caused either by foreign bodies or by fluid aspiration, hypoxia (decreased oxygen in the organ/ tissue), hypoxemia (decreased oxygen in the blood) and asphyxia appear. Subsequently, if the obstruction is not reversed, neuronal injury and cardiorespiratory arrest ensue. Head trauma can occur through any injury resulting from a blunt or penetrating force to the head that leads to involvement of vessels and meninges, and loss of consciousness is a possible consequence of this process. 12,21 In addition, mental confusion, convulsion and focal deficit may be symptoms associated with head trauma. 13 In our study, we found that only one passenger (5.3%) died due to brain hemorrhage and mechanical asphyxia after head trauma. Drowning can be attributed as a secondary mechanism resulting from encephalic lesion, which, through compromising the level of consciousness, makes the victim unable to remain on the water surface, thus causing subsequent drowning.
Regarding bodily injury, injuries produced by blunt instruments generate blunt injuries and these include abrasions, ecchymoses and hematomas. 22   IPO = inability to perform usual occupations for more than thirty days; PWL = permanent weakness of limb or impairment of its sensation or function, or acceleration of labor; PDW = permanent disability to work, incurable disease, loss or disablement of limb or loss of its sensation or function, permanent deformity or abortion; * frequency (percentage).

CONCLUSION
This study showed that injuries such as ecchymosis and abrasions were the ones most commonly found among the victims, and the main instruments that produced these injuries were blunt instruments. Moreover, it was observed that the main cause of death was mechanical asphyxiation through drowning, and that physical-chemical media were mostly responsible for causing lethal trauma.
Women were the main victims of this maritime accident, in relation to both bodily injuries and deaths. However, it was not possible to determine how many men and how many women in total were present on the boat, and this can be considered to be a limitation of this study, since women may have been more affected because they were present in larger numbers on the boat.
Accidents involving boats and ships occur widely around the world, and are responsible for large numbers of deaths through drowning. The present study is relevant in that it brings specific data from a maritime accident and thus contributes support for strategies aimed towards prevention of injuries in such accidents.
It is essential to develop measures for improving the safety of navigation, such as training for the crew, safety policies that encourage the use of life jackets and, lastly, stimulation of vessel inspections, so that the number of deaths can be minimized.