Applying Forces Measured at the Hands to Estimate L5/S1 Compression During Manual Patient Bed-to-Wheelchair Transfers Across Different Levels of Patient Assist

Abstract

Transferring a patient from a bed to a wheelchair is important for patient well-being. Research has shown that manually performing this task exposes healthcare workers (HCWs) to lower back kinetic demands that can exceed safety standards, necessitating the use of mechanical lift equipment. However, HCWs still commonly perform this task manually, especially for lighter patients who are capable of assisting. Although lower back kinetic demands are presumably dependent upon the patients (in)ability to assist during the transfer, this has not been systematically tested. Therefore, the primary aim of this research was to compare the peak L5/S1 intervertebral joint (IVJ) compressive force demands during a bed-to-wheelchair manual transfer across different levels of simulated patient assist (0%, 18%, and 36% of patient bodyweight). We also compared peak IVJ compressive forces from an approach using external forces directly measured at the hands of the HCW, with an alternative traditional approach that assumed the patient’s mass was fully lifted by the HCW throughout the transfer. Peak L5/S1 IVJ compressive forces were lower ( p < .001) during the 36% than the 0% and 18% bodyweight patient assist conditions when applying the measured forces at the hand. Overall, peak compressive forces were lower ( p < .001) and tended to occur at different phases of the transfer when applying the measured forces at the hand versus assuming all the patient’s mass was being lifted. Our results emphasize the importance of accurately modeling the forces at the hands when estimating in vivo demands. Further, these findings suggest that encouraging the patient to assist during transfers may reduce IVJ forces on HCWs, but for heavier patients even a modest degree of patient assistance is not likely to protect the HCW from elevated spine loads. In most circumstances, lift equipment is warranted.