Nitrogen Scuba.pdf

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Lubomir Straka,
M.D., Ph.D.; Frantisek Novomesky,
M.D., Ph.D.; Anton Gavel,
Juraj Mlynar,
Ing., C.Sc.; and Petr Hejna,
M.D., Ph.D.
Suicidal Nitrogen Inhalation by use of Scuba
Full-Face Diving Mask
ABSTRACT: A 29-year-old man was found dead lying on the bed in a hotel room in a famous Slovak mountain resort. He had a full-face
diving mask on his face, connected through a diving breath regulator to a valve of an industrial (nondiving) high-pressure tank containing
pure 100% nitrogen. The breath regulator (open-circuit type) used allowed inhalation of nitrogen without addition of open air, and the full-face
diving mask assured aspiration of the gas even during the time of unconsciousness. At autopsy, we found the typical signs of suffocation.
Toxicological analysis revealed 94.7% content of nitrogen in alveolar air. Following the completion of the police investigation, the manner of
death was classified as a suicide. Within the medico-legal literature, there has been only one similar case of suicidal nitrogen inhalation
described (1).
KEYWORDS: forensic science, forensic pathology, suicide, nitrogen, nitrogen asphyxiation, gaseous suffocation, full-face diving mask, sud-
den sniffing death, analysis of alveolar air
Nitrogen (N
) as a separate gas element was discovered in
1772 independently by D. Rutherford and H. Cavendish.
Later, A. Lavoisier declared nitrogen as the principle compo-
nent of Earths atmosphere. Nitrogen is physiologically an
inert, nontoxic gas, not involved in human metabolism. In
water and soils, nitrogen can be found in the form of nitrates
and nitrites. In the human body, nitrogen is a constituent ele-
ment of amino acids and thus of proteins and nucleic acids
(DNA and RNA).
Nitrogen, like argon, methane, propane, and carbon dioxide,
is considered to be a simple asphyxiate gas. It may displace
oxygen from the inhaled air causing a life-threatening condi-
tion. Reduction in atmospheric oxygen to less than 25% of
normal value can lead to rapid unconsciousness and death in
In this paper, we report on the analysis of a suicide of a
29-year-old man committed by inhalation of 100% nitrogen. In
the medico-legal literature, there has been only one similar case
of suicide by inhalation of nitrogen described (1).
Case Report
Case History
A 29-year-old student from Germany was found dead in a
hotel room on the last day of his 3-day biking tour at a moun-
tain resort. According to hotel staff, he had been unaccompanied,
he was only in obligatory contact with the reception desk and
was last seen in the evening several hours prior to his death. His
undressed body was found by a cleaning staff lying on a bed in
the supine position with his upper arms extended sideways
(Fig. 1).
There was a full-face diving mask (CRESSI-SUB, Genoa,
Italy) found on the face of the victim, being snugly sealed by
rubber straps (Fig. 2). The glass of the full-face mask was
covered with tiny droplets of the condensed vapor on the
inner side. The full-face diving mask was connected with a
second stage of standard open-circuit scuba (self-contained
underwater breathing apparatus, NOAA) diving regulator (See-
mann-Sub, Germany). The 2nd stage of the above-mentioned
regulator was connected via a flexible medium-pressure rubber
hose with the 1st stage of the scuba breathing system used.
Finally, the 1st stage of the regulator was firmly screwed into
the orifice of a valve of a high-pressure industrial gas tank
(inner capacity 6 L, remaining pressure 87 bars; L
ubke, Ger-
many), filled with pure nitrogen. Both regulators were in the
open position.
There was also a notebook, tourist map, navigational instru-
ments, wallet (with credit cards and a large amount of cash), and
a cellular phone on the table besides the body. In the lobby of
the room was a mountain bike. The police investigator, after
consultation with a public prosecutor and forensic expert, asked
for a medico-legal autopsy of the deceased (Fig. 3).
Institute of Forensic Medicine and Medicolegal Expertises, Jessenius
Faculty of Medicine, Comenius University, University Hospital, Kollarova 2,
036 01 Martin, Slovak Republic.
Department of Forensic Medicine, Health Care Surveillance Authority,
Banicka 803, 058 01 Poprad, Slovak Republic.
Department of Forensic Medicine, Health Care Surveillance Authority,
Antolska 11, 845 45 Bratislava, Slovak Republic.
Institute of Forensic Medicine, Faculty of Medicine, Charles University,
Sokolská 581, 500 05 Hradec Kralove, Czech Republic.1
Received 15 Mar. 2012; and in revised form 7 Sept. 2012; accepted
6 Oct. 2012.
©2013 American Academy of Forensic Sciences 1
J Forensic Sci,2013
doi: 10.1111/1556-4029.12239
Available online at:
Autopsy Findings
The male deceased was 183 cm tall and weighed 90 kg. On
external examination, there was intensive postmortem lividity,
hyperemia and pin-point hemorrhages, and multiple petechiae on
the skin of the shoulders. There was no evidence of trauma.
The internal examination revealed the following findings: the
brain of the deceased was swollen with dilatation and congestion
of blood vessels in the leptomeninges. Both lungs were enlarged,
congested, and edematous (left lung weight 750 g; right lung
weight 950 g). Tiny hemorrhagic foci were found on the pleura
of both lungs (Fig. 4). There was a pinkish mucous froth in the
airways. The heart was excessively dilated, and the muscular
walls were flaccid, with a total loss of tonus. The abdominal
organs were congested, and the liver was slightly enlarged
(1670 g) without, however, visible morphological changes. The
blood within the whole body was dark red and fluid. The remin-
der of autopsy was unremarkable.
Microscopic Findings
Microscopy of the lungs revealed diffuse foci of intra-alveolar
hemorrhagic edema, together with acute emphysema of alveoli
and passive congestion of septal vasculature. A microscopic
examination of the brain revealed pericellular and perivascular
edema with passive congestion of the capillaries. The micro-
scopic structure of the other parenchymatous organs was found
to be normal and appropriate to the age of the deceased. All the
organs were congested due to terminal circulation failure.
Toxicological Analyses
Samples of blood, urine, brain, lungs, suprarenal gland, and
adipose tissue were investigated using screening (thin layer chro-
matography; immunochromatographic assay) and specific meth-
ods (gas chromatography with head-space injection; gas
chromatography with mass selective detector). Analyses were
focused on drugs, drugs of abuse, ethyl alcohol, and other vola-
tile compounds.
Alcohol and volatile compounds in blood and drugs testing
resulted in negative findings.
Isolation of the alveolar air from the lungs to special plastic
bags (24) was performed immediately after isolation of the lung
samples at the autopsy. Analysis of the air isolated from both
lungs was performed separately, in a specialized accredited test-
ing laboratory, focused to nitrogen, oxygen, and carbon oxide
FIG. 2––Diving full-face mask tightly fixed on the face.
FIG. 3––Diving mask connected to a high-pressure tank.
FIG. 4––Tiny hemorrhagic foci on the pleura of both lung lobes.
FIG. 1––The body of deceased with a diving full-face mask fixed on the