The public health role of Poison Centres - Signals from human cases, examples of collaboration between Poisons Centres and Public Health Authorities

Background: Based on a Federal Institute for Risk Assessment (BfR) detailed analysis (57,093 reports between 1990-2008) of aspiration cases with liquid preparations, the aspiration risk is clearly associated with the ingestion of distinct aliphatic hydrocarbons with a chain length from C8 to C16. These are the main compounds of paraffin-containing lamp oils, grill-lighters and kerosene. Based on their typical low viscosity, low surface tension and low vapour pressure these substances can enter the deep spaces of the lung. More than 320 serious cases and five deaths of children have been documented in the BfR since 1990 with the typical signs of lack of oxygenation, giving strong clinical indications for an oxygen intra-alveolar diffusion barrier effect. To prove this hypothesis, the intra-alveolar surface and the oxygen transfer was simulated in an in vitro Alveolar Space Chamber (ASC) experiment. Methods: A gas-tight Plexiglass-measuring chamber (diameter 115 mm, height 115 mm, wall thickness 15 mm) was half-filled with fluorocarbon (FC-43) to generate a liquid-gas surface to simulate the alveolar surface. The oxygen-transport through the surface was measured in the bottom liquid part of the chamber by a Unisense oxygen micro sensor, connected to a high-sensitivity Pico-ammeter. Results: The results of the experiments revealed that the alveolar surfactant can be considered as a strong accelerator to the oxygen transfer into the liquid space of the capillary lung system. In contrast to these findings, generated microfilms of lamp oils reduce the transfer of oxygen through the surface to a high extent (minimum 9-15 fold). Transferring these findings to the clinical course of the documented serious lamp oil aspiration, the ASC-experiment could give clear indications of the pathophysiological mechanism. The characteristic physico-chemical properties of ingested lamp oils gives these liquids the capacity to spread deep into the lung, and finally into the alveolar spaces with the effect of building up a persistent diffusion barrier for oxygen. This could explain the severe asphyxia and death documented in BfR cases. Conclusion: The ASC-experiment gives a plausible understanding of the clinical findings in cases of serious lamp oil aspirations. The experiment is currently being extended to find new additional therapeutic tasks in cases of severe aspiration.