SOFT 2004 Meeting Abstracts - Society of Forensic Toxicologists
SOFT 2004 Meeting Abstracts - Society of Forensic Toxicologists
SOFT 2004 Meeting Abstracts - Society of Forensic Toxicologists
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P65<br />
POSTMORTEM BLOOD ALCOHOL RELIABILITY: FEMORAL SAMPLING<br />
A.E. Hodda*, <strong>Forensic</strong> Toxicology, DALIICPMR, Lidcombe, Australia<br />
P. Ellis, Dept. <strong>Forensic</strong> Medicine, ICPMR, Westrnead, Australia<br />
The analysis <strong>of</strong> blood for alcohol is one <strong>of</strong> the more fundamental analysis undertaken by a forensic <br />
toxicology laboratory. The sources <strong>of</strong> error in the laboratory are well documented and international <br />
standards <strong>of</strong> laboratory practice (AS/ISO 17025) have been developed to safeguard the analytical <br />
processes, for any analysis. Discrepancies in the alcohol levels in post mortem specimens from a recent <br />
. vehicle accident death resulted in a detailed review <strong>of</strong> all aspects <strong>of</strong> the post mortem process. In this case <br />
two femoral blood samples gave alcohol levels <strong>of</strong> 0.3 IOg/IOOmL but a vitreous humor sample had no <br />
detectable alcohol.<br />
A number <strong>of</strong> papers have been published on the importance <strong>of</strong> the source <strong>of</strong> blood samples used in<br />
quantitative alcohol and drug analysis. Errors due to contamination, dilution and "post mortem<br />
redistribution" are cited. The conclusion is that peripheral samples should be used and best source is the<br />
femoral vessels. The recommended procedure for post mortem femoral blood sampling is reviewed. The<br />
sampling point is normally within the pelvic girdle and it is clear that poor adherence to correct procedures<br />
can result in adventitious contamination or a non-representative blood sample. Traumatic deaths present the<br />
greatest risk <strong>of</strong> contamination. The Laboratory receives approximately 3000 toxicology cases per year and<br />
a review <strong>of</strong> 2 years showed the median volume <strong>of</strong> preserved blood submitted from coronial cases was<br />
20mL.<br />
Mathematical modelling demonstrated that 200j.IL (4 drops) <strong>of</strong> an alcoholic spirit in the pelvic cavity could<br />
result in blood alcohol levels <strong>of</strong> 0.300g/l OOmL, if allowed to contaminate a 20mL blood sample. Several<br />
tables are presented <strong>of</strong> various collected blood volumes and potential contamination factors.<br />
The reliability and predictability <strong>of</strong> comparing blood and vitreous humor alcohol .levels was also tested. A<br />
set <strong>of</strong>33 blood alcohol levels greater than 0.200g/100mL were compared to their respective vitreous humor<br />
alcohol levels. The regression equation was y=1.2734x-O.0451, the R2 was 0.9488. This result was similar<br />
to other reports and demonstrated the value <strong>of</strong> this comparison as well as the improbable results for the<br />
reviewed case.<br />
The review did not categorically identify the source <strong>of</strong> error in this case but the work has highlighted the<br />
ease <strong>of</strong> introducing significant errors in blood alcohol analysis. It has also supported the strong correlation<br />
between blood alcohol and vitreous humor. This observation makes this specimen particularly useful in<br />
contentious toxicology cases and should be taken in matters involving severe trauma. The growing<br />
convention in forensic toxicology is to use femoral blood samples for quantitative analysis, is endorsed but<br />
correct sampling procedures must be followed by pathologists.<br />
Keywords: Blood alcohol, error, femoral, vitreous humor.<br />
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