Nursing Mechanisms of Intravenous Medication Loss in Adult Intensive Care: A Mixed‐Methods Systematic Review

BACKGROUND: Adult ICU medication loss is reported using non-equivalent forms and denominators, limiting interpretation and intervention design. AIMS: To examine loss measurement, nursing mechanisms, intervention evidence and balancing outcomes. STUDY DESIGN: Convergent segregated mixed-methods systematic review. Three databases were searched to 1 July 2026, with citation searching, metadata checks and an uncapped rerun of two capped PubMed arms. Quantitative results remained in native units; qualitative findings were synthesised separately and integrated. MMAT 2018 was applied by design category; two reviewers checked screening, extraction and appraisal. RESULTS: Of 768 screened records (576 primary; 192 rerun), 79 reports were assessed with retained sources. Four reports could not be retrieved. Twenty-five reports from 21 independent studies were included; the rerun added none. Categories were prepared-unused medication (11), post-order or post-event loss (7), partial-container residual (8), delivery-system residual (3) and material-flow loss (4); categories were nonexclusive. Denominators were explicit in 10 studies, partial in 5 and absent in 6. No studies met pooling criteria. Two qualitative studies generated six low-confidence CERQual findings. Intervention evidence was uncontrolled, modelled or proposal-based; balancing outcomes were uncommon. CONCLUSIONS: Adult ICU loss comprised non-equivalent quantities, not one waste prevalence, and no study related it to a patient outcome. Studies would need to specify loss form, numerator, denominator, observation window, workflow node, result origin and balancing outcomes alongside resource use. RELEVANCE TO CLINICAL PRACTICE: Order review before non-urgent preparation, reconstitution and checking, storage and return pathways, and syringe, pump and line handling are candidate targets; no controlled adult ICU study has shown reduced loss without affecting access, dose delivery, sterility, compatibility or workload.