Abstract
Several incidents were reported within a few months about errors of flow volume of intravenous infusion when infusion pump was engaged to maintain accurate flow rate. These reports prompted us to inquire the actual clinical condition and to resolve underlying problems. The infusion pump used in our hospital controls flow rate by peristaltic device, where the flow rate depends on the diameter of the infusion tube. Most of the reports described that the actual infusion volume did not reach the expected volume. This fact suggests, together with the mechanical characteristic of the peristaltic method, that the insufficient flow volume might be related to a narrowed diameter of the infusion tube induced by stretching while installing it on the pump. We therefore investigated the relationship between tension by stretch on the tube and flow volume. The residual volume of infusion was measured daily for inpatients who underwent24hr continuous intravenous infusion with a pump. The residual ratio was12.2±3.2%(n=14). Then, the relationship between stretch and flow volume was investigated experimentally. Compared with the control experiment the total volume of water significantly decreased after24hr operation of the pump with mild- or strong-manual stretching of infusion tubes. A quantitative analysis with Og, 100g, 200g and 500g weight revealed an inverse relationship between weight and total flow volume. These results indicate that even a mild stretch of the infusion tube at installation on the pump can result in a decreased flow volume. This information was explained thoroughly to the nursing staff. As a result, reexamination of the clinical residual ratio showed a significant decrease of 8.1±2.4%(p<0.01, n=16) as compared with the control experiment. In conclusion, careful operation is required for the installation of infusion tubes on the pump to perform an accurate infusion.
