Journal of Forensic Investigation
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Research Article
Cause of Death in Carbonized Children: What is The Role of Carboxyhemoglobin?
Miziara ID1* and Miziara CSMG2
1Department of Legal Medicine, Ethics, Social and Occupational Health, São Paulo University Brazil
2Discipline of Legal Medicine, ABC School of Medicine,Santo André, Brazil.
*Address for Correspondence: Mziara ID, Associate Professor, Head of Department of Legal Medicine, Ethics, Social and Occupational Health, São Paulo University Faculty of Medicine, São Paulo-Brazil; Email: Ivan.miziara@usp.br
Submission: 19 May, 2021;
Accepted: 20 June, 2021;
Published: 25 June, 2021
Copyright: © 2021 Miziara ID, et al. This is an open access article
distributed under the Creative Commons Attribution License, which
permits unrestricted use, distribution, and reproduction in any medium,
provided the original work is properly cited.
Abstract
While fre-related deaths are regularly encountered by medical
examiners and in the forensic practice, one of the most important signs
that death occurred by carbon monoxide poisoning is the blood level of
Carboxyhemoglobin, which usually is stated by the literature as above
50%. We examined retrospectively the reports of 16 children charred
corpses that died in closed space. The dosage of Carboxyhemoglobin
of 10 of them was less than 50%. In absence of any other plausible
manner of death, the examiners concluded that the cause of death
was due to carbon monoxide poisoning. The authors emphasize the
necessity of further research to establish adequately what is the lethal
blood level of carboxyhemoglobin in children.
Introduction
The World Health Organization estimated that 265,000 deaths
occurred every year caused by burns1. When a body is recovered
from the scene of a fre, from the forensic point of view, is important
to determine the manner of death. As stated by Melez et al [1], “a
multidisciplinary approach is crucial to uncover the manner of
death.”In forensic practice, bodies of unknown persons or carbonized
corpses have to be formally identified. In the local scene of a fire, is
crucial to the forensic agent to identify if the bodies he found were
victims of the fire if they were already dead, or victim of homicide,
for example. Te majorityof all fre deaths are due to smoke and
soot inhalation. Te most common toxic agent in this condition is
carboxyhemoglobin (COHb), whose levels above 40% to 60% are
frequently cited as fatal [2]. Besides, fire-related deaths may also
occur due to other causes as sequelae of thermal injuries, antecedent
trauma, or even homicide. As pointed by Dolinak, Matshes, and
Lew [3], “death may ensue because of the burns themselves, smoke
inhalation, or some combination of the two.” Thus to determine the
cause of death it must first be established whether the victim was alive
at the time of the fire and what caused the death, insofar as burning
the body may be an attempt to hide the traces of the real cause of
death, as in homicides by fireearms or the use of blunt instruments.
At this point, two things are important and relevant as evidence that
the person was alive at the time of the fire: soot lining the airways
(Montalti sign) and an elevated blood carboxyhemoglobin saturation.
The purpose of toxicology is the study of toxic agents, such
as drugs and pharmaceuticals, and their relationship with living
organisms, causing everything from minor functional changes to
death. Forensic toxicology thus encompasses essential techniques to
prepare evidence for criminal investigations. As we said, one of the
problems to be solved in medico-legal necropsy that require the help
of forensic toxicology in fre victims involves primarily the following objectives: determination of the cause of death, that is whether the
death was due to the effects of the burns suffered by the victim, or if
the death was the result of inhaling a lethal dose carbon monoxide
(with the subsequent formation of carboxyhemoglobin at levels
incompatible with life). In children’s charred corpses, there is an
additional problem: there are not many studies that could answer the
question: what is the lethal level of COHb in children?
According to Spitz “even low levels of carboxyhemoglobin
are signifcant. A few breaths sufce to accumulate a meaningful
concentration.” [4]. It is important to note that while the presence of
COHb is proof of life when the fire started, its absence does not imply
that death occurred before the fire.
Absence and low concentrations can appear in situations such as
flash fires, conflagration in a chemical plant, in warfare or explosion,
when death may be instantaneous. Most of these deaths are not
caused by burns, but, as stated by Saukko and Knight, by inhalation
of fumes produced by the combustion of building structure and
contents. Carbon monoxide poisoning is an important aspect of most
fires – “indeed it is the major or even sole cause of death in many
victims of conflagrations, especially in house fires” [5].
Otherwise, according to forensic literature, levels of COHb
in the blood greater than 50% confirm death from CO poisoning,
concentrations between 10% and 50% indicate that the victim could
have been alive when the fire started, and concentrations below 10%
indicate that the victim was probably dead when the fire started [6]
Older individuals and those with signifcant medical disease (in
particular, heart disease) will have less physiological reserve and may
succumb to lower levels of COHb saturation – sometimes even at
levels as low as 20 percent [1].
Besides, it is important to point out that children have
physiological differences relative to adults, such as lower blood
volume, faster basal metabolism (which requires greater tissue oxygenation), and greater pulmonary ventilation [6,7] and therefore lethal levels of COHb in children may be lower than those found in
adults. Although the toxic levels reported in the literature for COHb
ranged between 25% and 85%[8] there are no standardized values
in the forensic literature for measuring COHb in children who are
victims of the fire. This aspect can become a major problem when
we examine the body of a charred child. Precisely for that reason, we
must be cautious in the interpretation of mildly elevated or low blood
levels of COHb in children’s charred corpses. Thus, the presence or
absence of soot in the respiratory airways is of great importance as
an indicator that the child was alive at the time of the fire. Remember
that COHb saturation will not be “artificially elevated” in a dead
person by being in or near a fire; soot will not enter the intact airways
of a person already dead before the fre. On the other hand, one must
consider that a person may have been alive during a fire, yet have
normal COHb saturation levels in the blood – as described in flash
fire victims. But is important to say that like any toxicology level the
interpretation of COHb levels must be interpreted in the context of
the entire case [4]
Thus the main objective of this research is to describe the
necroscopic examination findings and the blood level of COHb in a
sample of children charred corpses. This has real importance to the
forensic practitioner because in his investigation of a scene of fire it
can be crucial to identify if it was an accident or a potential crime.
Methods
We have conducted a retrospective and descriptive study by
collecting information contained in the necroscopic reports of the
Unity of Forensic Anthropology of Medico-Legal Institute of São
Paulo State (IML). Te data included 16 children under the age of 12
years who were victims of fres in a closed space from 2010 to 2017.
All causes of death were signed as intoxication by Carbon Monoxide.
The collected data were grouped by year of occurrence, victims,
presence of the Montalti sign, the concentration of COHb, place of
encounter of the corpse, and cause of death as recorded in the necropsy
reports. Levels of COHb were determined in blood samples from 16
charred corpses that were autopsied between 2010 and 2017 in the
toxicology laboratory of the Department of Legal Medicine, Faculty
of Medicine, University of São Paulo. Percent of carboxyhemoglobin
(% COHb) was determined by the micro-diffusion method [9]. All
the victims were submitted to a complete x-ray examination, before
the necroscopic exam
Results
(Table 1) gathers the data collected from 16 child victims of fire,
aged 12 years or under from 2010 to 2017. Of the 16 children, 10
(62.5%) died with COHb concentrations below 50% and 6 (37.5%)
had COHb concentrations greater than 50%. Te extent of the burns
was less than or equal 30% of body surface area (BSA) in all victims
(100%). None of the victims presented any sign of fatal trauma.
Signs of vitality, defined as either the presence of soot in the airways
(Montalti sign)or detectable COHb in the blood were present in all
sixteen victims. In absence of other plausible causes, all causes of
death as stated in the necroscopic reports were CO poisoning.
Discussion
The forensic literature has established a percentage equal toor greater than 50% of COHb in the blood as a lethal value (Table 1).
However, this study reveals that more than half of deaths diagnosed
with CO poisoning in our population (e.g., children aged below 12
years) occurred in victims with COHb concentrations below 50%
- that is, in percentages lower than those described in the literature
as a lethal dose for adults. In addition to the values found, it can
be said that CO poisoning mortality in children can be present at
lower concentrations than in adults since children present different
physiologies, making them more sensitive to poisoning in lower
concentrations in the closed environment. This can cause doubt when
it comes to identifying the cause of death; in such cases, the presence
of the Montalti sign is essential to confrm the cause of death [5,7,10]
Is necessary to say that we don’t investigate the presence of
hydrogen cyanide in the blood of the children, which can be a
confusion factor. As stated by Melez et al. [1], “the most important
death mechanism in fre is smoke inhalation. Rapid death can occur
due to carbon monoxide (CO) or hydrogen cyanide intoxication,
or asphyxia due to the lack of oxygen in the air.” Thus, the cause of
deaths found in the reports (e.g., intoxication by CO) could not be
exact and it was chosen, probably, because was the only objective
element the examiner had.
However, the analysis of these data serves to alert forensic
pathologists of the importance of accurate necroscopic examination
in carbonized children. In addition, future research must provide a
greater amount of data on COHb levels in the blood of children to
establish with certainty the lethal dose in these cases with minimum
safety.
Conclusion
In a sample of 16 charred corpses of children, we found 10 of
them with COHb blood level below 50% with no other cause of
death detectable. This find suggests that the lethal level of COHb
in children’s blood is less than in adults. But further researches are
necessary to clarify this important point in forensic medicine.