Postmortem Redistribution of Drugs Commonly Used in Rapid Sequence Induction for Anesthesia: A Review

Background: Rapid Sequence Induction (RSI) is a widely used method for emergency airway management in critically ill and clinically unstable patients. Beyond the risks inherent to the procedure itself, RSI is almost exclusively performed in emergency settings where patients present with severe physiological derangement and a high risk of aspiration. In postmortem examinations, forensic toxicology results may be influenced by the patient's clinical condition, the sampling site, the postmortem interval (PMI), and postmortem drug redistribution (PMR). This review aims to evaluate the existing literature regarding PMR of drugs commonly used during RSI. Methods: PubMed/MEDLINE, Embase and the Cochrane Library were searched for studies on PMR of drugs used in intravenous (IV) RSI (up to November 2025). Human and animal studies, patient populations comparable to critically ill individuals requiring RSI, and forensic case reports of exclusively IV drug administration were included. Studies on recreational use, overdose and non-IV administration were excluded. Results: Data on the PMR of IV-administered RSI drugs remain limited. Most available studies involve Intensive Care Unit (ICU) patients or individuals who underwent RSI in emergency settings. Fentanyl and midazolam appear to demonstrate notable PMR. Several factors influencing postmortem drug concentrations were identified. Although these findings are consistent with the existing literature, the small number of studies and the heterogeneity of data preclude definitive conclusions. Conclusions: Critical patient condition, including frailty due to advanced age, hemodynamic instability (particularly in ICU patients), hypoalbuminemia, body mass index (BMI), and injury and/or trauma, as well as the interval between IV drug administration and death, appear to affect postmortem concentrations of drugs used during RSI. The potential for PMR of certain agents, such as fentanyl and midazolam, adds further complexity. Given the scarcity of consolidated evidence and until further research provides more robust data, postmortem drug levels should not be interpreted as directly reflective of antemortem concentrations.