Effect of Parameters on Lumbar Compressive Force during Patient Transfer

Patient transfer (PT) tasks are a significant cause of low back pain (LBP) in caregivers. Adopting proper motion strategies is an effective and inexpensive approach to reduce the risk of LBP. However, since the standardization of PT tasks is not specified in ISO 11228, there is an increasing need to develop a quantitative assessment method for the lumbar safety of caregivers. Therefore, we aim to determine the effect of representative factors, extracted from caregivers’ movements and of external force, on peak compressive force (CF) in patient transfer tasks using the lumbar compressive force as a criterion. The CF at the lumbar region is estimated using a biomechanical simulator, and regression analysis is performed between the estimated CF and representative factors. The results imply that peak CF occurs in the incipience of transfer and occurs after the occurrence of the peak trunk angle. The results also indicate that the peak CF can be reduced by preventing the representative factors from simultaneously reaching the maximum values. In this study, we provide a method of reducing peak CF by estimating the timing and magnitude of the peak to help caregivers assess the severity of LBP risk in actual PT, which is expected to contribute to the standardization of PT tasks.