Should postmortem subclavian blood be considered a peripheral or central sample?

The phenomenon of postmortem redistribution has long been described, but the processes driving it have not, as yet, been fully elucidated. Peripheral blood samples are currently used, when available, in an effort to minimize the effects of postmortem redistribution on drug concentrations, but what sources of blood are peripheral sources? A study was undertaken to determine if postmortem subclavian (SC) blood should be considered a peripheral or central blood sample. Twenty-eight cases were identified in which drugs were quantified in at least 2 of the following blood sources: femoral (F), SC, and heart (H); the concentrations found in each source were compared. Twenty different drugs were analyzed including 6 antidepressants, 6 opioid medications and metabolites, 3 benzodiazepines, 2 antihistamines, 2 sedative hypnotics, and 1 muscle relaxant. Analysis found that SC blood concentrations reflect neither F nor H blood concentrations, with the exception of the benzodiazepines where SC blood concentrations closely mirrored H blood concentrations. Overall, SC blood drug concentrations tended to be 1.3 times greater than F blood and 0.77 times less than H blood. Therefore, it is recommended that the exact source of the blood, rather than simply "peripheral" or "central," be notated on toxicology results to ensure appropriate interpretation.