No. Heavy lungs do not independently establish that fentanyl caused a death. In an Orange County series of fentanyl-positive death investigations, combined lung weights were similar whether fentanyl was included in the certified cause of death or not. That comparison also had important selection and confounding limitations.
Which deaths were compared?
Havro and colleagues reviewed casework from 2018–2019, including 285 death investigations with fentanyl detected in central blood. Fentanyl was listed in the cause of death in 238 cases and was not listed in 47. Combined lung weights were available in 275 of the 285 cases.
The lung-weight comparison therefore concerned people already selected for fentanyl detection. It did not compare a representative group of fentanyl-caused deaths with opioid-negative deaths. Availability of lung weights also differed from the complete case count; 275 should not be rewritten as 285 measured lung weights.
The cause-of-death classifications came from the medical examiner’s case determinations. They were not independently assigned through a blinded lung-weight diagnostic experiment.
What were the actual lung weights?
Across available records, combined lung weight ranged from 450 to 3,630 g, with a mean of 1,514 g and median of 1,450 g.
For cases where fentanyl was included in the cause of death, the reported mean was 1,506 g, median 1,460 g and range 560–3,010 g. For cases where fentanyl was not included, the mean was 1,596 g, median 1,400 g and range 450–3,630 g.
These descriptive distributions overlapped substantially. The highest reported lung weight occurred within the group where fentanyl was not included in the cause of death. The authors considered lung weight unreliable for distinguishing the two groups in this dataset. They did not report a validated cutoff, diagnostic sensitivity or specificity for this purpose.
Why the comparison could not isolate fentanyl’s effect
Other opioids were detected in 91 death-investigation cases, including substances such as morphine, methadone, hydrocodone and oxycodone. Those exposures could also be relevant to pulmonary findings. Other diseases and circumstances of death likewise require consideration.
Cases without fentanyl in the cause of death included coronary disease, myocardial infarction, congestive heart failure, hanging and other drug toxicity. A lung weight is consequently not a drug-specific chemical measurement, and this observational comparison did not isolate the effect of fentanyl from every competing explanation.
The authors noted that an opioid-negative comparison group would improve the investigation. Its absence prevents concluding either that fentanyl never affects lung weight or that heavy lungs specifically identify a fatal fentanyl effect.
What did the toxicology establish?
Central blood was collected near the heart cavity at autopsy, preserved with sodium fluoride and potassium oxalate and refrigerated at 4°C. Screening by LC–quadrupole time-of-flight MS was followed by confirmatory quantitative LC–MS/MS. Duplicate quantitative results were averaged.
The fentanyl method used a 0.5–32 ng/mL calibration range, with validated detection and quantification limits of 0.5 ng/mL. Reported bias and precision were within 20% at the tested conditions. These characteristics support interpreting an analytical result; they do not make an anatomical finding specific for fentanyl poisoning.
How to use the finding responsibly
Retain the combined lung weight as one autopsy observation alongside the medical history, full autopsy, treatment history, toxicology and other case evidence. Detection of fentanyl plus heavy lungs is not, by itself, a validated rule for attribution.
A separate issue is whether the fentanyl concentration supplies a fatal threshold. The comparison of living-patient and postmortem fentanyl measurements explains why concentration-only conclusions also need caution.
Primary source
Havro V, Casassa N, Andera K, Mata D. A Two-Year Review of Fentanyl in Driving under the Influence and Postmortem Cases in Orange County, CA, USA. Journal of Analytical Toxicology. 2022;46(8):875–881. doi:10.1093/jat/bkac030.
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