In healthcare practice, there may be critically injured patients in whom catheterisation of a peripheral venous access is not possible. In these cases, intraosseous access may be the preferred technique, using an intraosseous vascular access device (IOVA). Such devices can be used for infusion or administration of drugs in the same way as other catheterisations, which improves emergency care times, as it is a procedure that can be performed in seconds to a minute. The aim of this study was to analyse the level of knowledge of nursing staff working in emergency departments regarding the management of the intraosseous vascular access devices. To this end, a cross-sectional online study was carried out using an anonymous questionnaire administered to all professionals working in emergency and critical care units (ECCUs) in Granada district (Spain). The results show that 60% of the participants believe that with the knowledge they have, they would not be able to perform intraosseous vascular access, and 74% of the participants believe that the low use of this device is due to insufficient training. The obtained results suggest that the intraosseous access route, although it is a safe and quick way of achieving venous access in critical situations, is considered a secondary form of access because the knowledge of emergency and critical care professionals is insufficient, given the totality of the participants demanding more training in the management of intraosseous access devices. Therefore, the implementation of theoretical/practical training programmes related to intraosseous access (IO) could promote the continuous training of nurses working in ECCUs, in addition to improving the quality of care in emergency and critical care situations.