Comparison of Drug Concentrations Taken From Clamped and Unclamped Femoral Vessels

Abstract

Postmortem drug concentrations may vary depending on sampling site, volume of blood collected, and method of sampling, making it important to analyze specimens from different sites in the body to detect postmortem redistribution and avoid erroneous conclusions on cause and manner of death. Using a blind stick method to draw large amounts of blood from the femoral vessel may increase the likelihood of contamination with blood from more central sites. It has been suggested that clamping the femoral vessel before drawing the sample may eliminate possible contribution from central sites. Eight drugs from four different drug classes were evaluated to determine the difference between drug concentrations in clamped and blind stick femoral blood. Drug concentrations of three selective serotonin reuptake inhibitors, or SSRIs (sertraline, paroxetine, citalopram), two benzodiazepines (diazepam and alprazolam), two antihistamines (diphenhydramine and promethazine), and one opiate (hydrocodone) were evaluated in clamped femoral blood, blind stick femoral blood, and heart blood and compared using concentration ratios and linear regression analysis. Clamped femoral blood concentrations and blind stick femoral blood concentrations were found to have good predictability across all drug classes with ratios around 1.0, indicating good correlation between blind stick femoral and clamped femoral samples. Therefore, it can be concluded that a blind stick femoral blood sample does not have significant redistribution from central sites and is of equivalent quality to a clamped femoral sample.

Postmortem drug concentration intervals for the non-intoxicated state – A review

“…Evaluation of different sampling techniques has yielded similar results. 27 A systematic study involving duplicate sampling from the femoral veins showed a considerable random sampling variation yielding a preanalytical uncertainty component superseding the analytical variation considerably. 28 …”

Interpretación de resultados toxicológicos post-mórtem: criterios de garantía de calidad

“…La influencia de las condiciones preanalíticas sobre la incertidumbre de la medida de concentración puede ser importante e incluso mayor que la incertidumbre asociada al método analítico 16 . Por ejemplo, se ha demostrado que la incertidumbre asociada a la concentración de metadona en sangre femoral se incrementa 5 veces cuando se tienen en cuenta los factores preanalíticos 17 .…”

Complete Republication: National Association of Medical Examiners Position Paper: Recommendations for the Investigation, Diagnosis, and Certification of Deaths Related to Opioid Drugs

“…Although some ME/Cs ligate the femoral vein and draw distal to the ligation under direct visualization, at least one study shows that samples drawn by blind stick access to the femoral vein yield closely comparable concentrations [18]. If femoral vein blood is not available, then blood from the subclavian vein, the right atrium of the heart, or any other intact blood vessel is the next choice, listed in decreasing order of desirability [8].…”