Hagen Dominik, Obermayer Astrid, Stoiber Walter, Steinbacher Peter, Zhao Jian, Monticelli Fabio C, Pittner Stefan
Dept. of Environment and Biodiversity, Paris-Lodron University of Salzburg, Salzburg, Austria.
Dept. of Forensic Medicine and Forensic Psychiatry, Salzburg, Austria.
Int J Legal Med. 2025 Jul;139(4):1597-1607. doi: 10.1007/s00414-025-03441-1. Epub 2025 Feb 8.
The diagnosis of drowning represents a considerable challenge in forensic practice. Typically, it is made by excluding other potential causes of death while concurrently identifying key signs of drowning. However, in cases with a prolonged postmortem interval, these characteristic signs are often absent. To support drowning diagnoses, various supplementary methods have been introduced over time, prominently including qualitative and quantitative diatom tests. One such approach involves comparing diatom concentrations in the drowning medium (immersion water) and in the lung tissue to determine lung-to-drowning medium (L/D) ratios. L/D-ratios above 2 are thereby seen as safe indicators of drowning, as higher diatom concentrations in the lungs than in the drowning medium can only be explained by active water aspiration. Previous studies typically investigated diatom concentrations in the tip of the lung's left superior lobe, as this region is thought to generally experience the lowest physiological pressure. However, no experimental data have yet confirmed the relevance of this in drowning incidents. It is also still unclear how diatoms are distributed within the lung during aspiration and how L/D-ratios could vary if samples from other lung regions are used for L/D-ratio calculations. To address these uncertainties, we conducted a study assessing diatom concentrations across seven positions from all pulmonary lobes in 25 drowning cases. Our aim was to identify the lung regions with the lowest probability of diatom uptake, thereby maximizing the reliability of L/D-ratios as a forensic tool. Our findings show that the left superior lung lobe is indeed the site of the lowest diatom accumulation and thus optimal for L/D-ratio related drowning diagnosis. Nonetheless, due to the higher sensitivity for diatom uptake, inclusion of other lung positions may also be recommended to strengthen diagnostic accuracy, especially in cases with generally low L/D-ratios.
溺水的诊断在法医实践中是一项颇具挑战的工作。通常，诊断是通过排除其他潜在死因，同时识别溺水的关键迹象来做出的。然而，在死后间隔时间较长的案例中，这些特征性迹象往往并不存在。为辅助溺水诊断，多年来引入了各种补充方法，其中显著的包括定性和定量硅藻检测。一种方法是比较溺水介质（浸泡水）和肺组织中的硅藻浓度，以确定肺与溺水介质（L/D）的比率。L/D比率高于2被视为溺水的可靠指标，因为肺部硅藻浓度高于溺水介质只能通过主动吸入水来解释。以往的研究通常调查肺左上叶尖端的硅藻浓度，因为该区域被认为一般承受的生理压力最低。然而，尚无实验数据证实这在溺水事件中的相关性。目前仍不清楚在吸入过程中硅藻在肺内如何分布，以及如果使用来自肺其他区域的样本进行L/D比率计算，L/D比率会如何变化。为解决这些不确定性，我们开展了一项研究，评估了25例溺水案例中所有肺叶七个位置的硅藻浓度。我们的目的是确定硅藻摄取可能性最低的肺区域，从而最大限度地提高L/D比率作为法医工具的可靠性。我们的研究结果表明，左上肺叶确实是硅藻积累最少的部位，因此对于与L/D比率相关的溺水诊断最为理想。尽管如此，由于对硅藻摄取的敏感性较高，也可建议纳入其他肺位置以提高诊断准确性，特别是在L/D比率普遍较低的案例中。
