Mixed Fentanyl–Benzodiazepine Case Documented Reversible Mobitz I Block

A transient conduction disturbance during mixed intoxication cannot identify the separate contribution of each detected drug.

What the supplied paper reports

A thirty-five-year-old man presented with somnolence, bradycardia and oxygen desaturation after a reported mixed overdose. ECG showed progressive PR prolongation with intermittent nonconducted P waves, consistent with Mobitz I block. During supportive treatment including oxygen, fluids and naloxone, rhythm improved through first-degree block to sinus rhythm within forty-eight hours.

What the findings cannot establish

The report lacked quantitative toxicology and could not definitively exclude all co-ingestants. A positive screen does not establish dose or simultaneous peak concentrations. Resolution during several interventions is compatible with reversibility but cannot prove a specific benzodiazepine mechanism.

Implications for forensic review

For a cardiac toxicology opinion, preserve serial ECG and oxygenation findings and compare alternative explanations. Naloxone response principally informs an opioid contribution; it is not a benzodiazepine reversal test. This case supports awareness of dynamic conduction abnormalities while requiring caution in assigning causation to one member of a mixed exposure.

Source and related reading

Source reviewed: Mobitz I Atrioventricular Block Following Combined Opioid and Benzodiazepine Overdose A Case Report (PMC13040611). The forensic applications above are interpretive analysis of the supplied paper.