Intravenous (IV) administration lines are in daily use in hospitals as a means of administering fluids and medications to patients (Gorski et al, 2021). Administration equipment has evolved from the practice of using a gravity feed in-line burette set, in order to intermittently deliver a fixed medication volume over a specified period of time, to the use of small-volume IV infusion bags to deliver the prescribed medication. The use of the in-line burette set allowed easy flushing of the IV administration line to clear the line of drug residue. This equipment seems to have fallen out of favour. Active flushing no longer appears to take place and current IV infusion practice of intermittent medication, diluted in small-volume bags, appears to accept that the infusion process is complete once the infusion bag is empty whether administered by gravity feed, traditional infusion pump, or smart infusion pump, irrespective of volume left in the IV administration line (Cousins, 2018). Cousins (2018), an independent safe medication practice consultant and former head of safe medication practice at the National Patient Safety Agency and NHS England, suggested that this current practice of administering small-volume infusions could be challenged in court as a breach of the Medicines Act 1968 in the UK.
Interestingly, the move away from the practice of flushing the IV administration line has received little attention until fairly recently in the literature, with a rapid response review by the then Canadian Agency for Drugs and Technologies in Health (2014) finding no relevant health technology assessments, systematic reviews, meta-analyses, randomised controlled trials, non-randomised studies, or evidence-based guidelines for flushing intravenous tubing following administration of medications, over a 5-year period from 2009 to 2014. The question of what to do with medication remaining in the line once an infusion bag is empty was raised in 2008 by nurses Hoefel et al (2008), when analysing nursing medication errors during intermittent vancomycin infusions. Following this, there appears to have been only one nursing publication cautioning against this practice error (Weeks, 2012) until a post on an online nursing blog (Infusion Nurse Blog, 2015), discussing a situation where a member of the public queried the logic of disposal of an antibiotic dose remaining in an infusion administration line once the infusion bag was empty. More recently, observational studies of clinical nurse practice have highlighted inconsistent IV administration practices (Furniss et al, 2018; Lyons et al, 2018; Morrow, 2018; Blandford et al, 2020; Rout et al, 2023) with optimal flushing practices observed mainly in long-term management of vascular access devices (VADs) used in oncology wards (Cooper et al, 2018).
The use of IV administration lines to deliver antimicrobial medicines should take into account potentially undelivered fluid remaining within the infusion set (Hoefel et al, 2008; Lam et al, 2013; Alexander and Zomp, 2015; Thoele et al, 2018; Morgan, 2019; Bolla et al, 2020; Anderson, 2021; Peyko, 2023). This has relevance for the full-dose delivery of intermittent medications, in particular, with implications for the emergence of antimicrobial resistance should the patient not receive the complete dose of antimicrobial medication (Weeks, 2012; Rout et al, 2019, Bolla et al, 2020; Rout et al, 2020; Dix, 2021; Gorski et al, 2021; Fady and Bennett, 2023). Unfortunately, professional guidance for this aspect of clinical practice has been slow to emerge (Fady and Bennett, 2023).
Infusion therapy guidelines, from both medical and nursing organisations (National Institute for Health and Care Excellence, 2017; Gorski et al, 2016; Royal College of Nursing (RCN), 2016) until recently did not refer to, or give recommendations for, the management of residual volume. The Infusion Therapy Standards of Practice is a comprehensive guideline document released by the Infusion Nurses Society in the USA, and updated every 5 years. Flushing and locking recommendations within the 2016 document were for maintenance of VADs only. These practice criteria outlined the steps taken for ensuring catheter patency, and locking recommendations, and offered references for these recommendations, accompanied by strength of the body of evidence. Flushing recommendations were, however, confined only to flushing the IV cannula, with no mention of residual fluid volume and how this should be managed by the nurse (Gorski et al, 2016). The updated 2021 guidelines, however, include a section advising practice on infusion medication:‘need for additional fluids for flushing the medication from the administration set’ and detailing minimising medication loss when administering small-volume secondary medication infusions (Gorski et al, 2021: S180). The RCN (2016)Standards for InfusionTherapy supports the management of VADs as outlined by the Infusion Nurses Society; although the document offered no recommendations for managing residual volume, it is currently under review and it remains to be seen whether future versions will cover it.
Disparate solutions to the retention of medication within the infusion line have been suggested: Lam et al (2013) proposed the use of higher doses to compensate for residual volume, and a laboratory study reported by Harding et al (2020) strongly supported the re-introduction of flushing practice to improve patient outcomes by receiving the complete dosage of prescribed medication. Published guidelines from the National Infusion and Vascular Access Society (NIVAS) in the UK presented several recommendations for the management of residual volume. These were: discarding the infusion set on completion of the intermittent drug infusion, flushing of the infusion set manually, and flushing the infusion set with a closed system such as that used for the administration of chemotherapy (Barton et al, 2019). NIVAS has since updated its guidelines to include flushing lines after infusing a medicine (Barton et al, 2021).
A scoping review has been chosen as the most suitable form of knowledge synthesis to profile the range of literature and present a broad overview of a topic, and has therefore become a useful way of identifying gaps in existing research (Arksey and O'Malley, 2005; Levac et al, 2010). Scoping reviews also allow for the inclusion of documents that may not be considered in other literature reviews. This grey literature allows examination of documents other than peer-reviewed academic papers or research studies (Cacchione, 2016; Munn et al, 2018; Peters et al, 2024). Landa et al (2011) suggested that the a priori publication of the methodology of a protocol is useful to support rigour by ensuring repeatability, and improves confidence in the results. A preliminary search of PROSPERO, Medline, the Cochrane Database of Systematic Reviews and the Joanna Briggs Institute (JBI) Database of Systematic Reviews and Implementation Reports was conducted and no current nor proposed scoping reviews or systematic reviews on the topic were identified. This review protocol was therefore registered with JBI and Open Science Framework, as a new protocol. The protocol set out here outlines the method intended to provide a profile of literature discussing the management of residual volume in hospital settings. As such, it is useful to pose questions of literature scoped relating to infusion practices, flushing practices, what happens to fluid remaining in the line, recommendations for delivery of this fluid, potential consequences of non-delivery of prescribed medication, impact on patient outcome, and possible impact on the environment when undelivered medication is discarded.
Methods
The proposed scoping review will adopt the methodology for scoping reviews as outlined in the 2024 JBI Manual for Evidence Synthesis (Peters et al, 2024). This extended methodology requires the use of an a priori scoping protocol and provides guidelines for documentation (Tricco et al, 2018). The stages of the proposed scoping review are: identifying the research question; identifying relevant studies; study selection; charting the data; collating, summarising and reporting results; and an optional sixth stage of consultation. In view of the current interest in the efficacy of infusion practices, it is deemed pertinent to examine existing and emerging literature in a structured sequential manner, over a specified time period. This repeated search process has been found to be useful to identify subsequent publications (Pham et al, 2014).
Review question
What is current clinical practice in the management of intermittent medication infusion residual volume within the hospital setting?
Objectives
The specific objectives of this scoping review are:
Inclusion and exclusion criteria
Eligibility criteria will be based on the ‘Population-Concept-Context’ or ‘PCC’ framework (Peters et al, 2024):
The full criteria are set out in Table 1.
| Inclusion criteria | Exclusion criteria |
|---|---|
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|
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Types of sources
This scoping review will consider quantitative, qualitative and mixed-methods study designs for inclusion. Systematic reviews and opinion articles will be considered for inclusion. In addition, infusion guidelines/standards/policies published by health professional societies and associations will also be considered.
Search strategy
The research objectives will be addressed using established JBI scoping review methodology (Peters et al, 2024) in order to map the literature for this topic, including empirical research, narrative and structured reviews of the literature, and society guidelines. The search strategy will aim to locate both published and unpublished primary studies, reviews, opinion pieces, and guidelines. An initial limited search of Medline and CINAHL was undertaken to identify articles on the topic. The text words contained in the titles and abstracts of relevant articles, and the index terms used to describe the articles, will be used to develop a full search strategy for Medline, CINAHL, PubMed and EBSCOhost (Table 2).
| Search | Query | Records |
|---|---|---|
| #1 | “Intermittent intravenous infusion” OR “Secondary infusion” OR “Piggy-back infusion” OR “Small volume infusion” | 93 |
| #2 | “Residual intravenous volume” OR “undelivered intravenous drug” | 510 |
| #3 | #1 and #2 | 14 |
Limited to 2000–2024, English language, hospital healthcare, intermittent IV infusions, intravenous piggyback, IVPB, secondary medications, small volume IV bags, residual volume
The search strategy, including all identified key words and index terms will be adapted for each included information source. Searches of relevant websites of healthcare societies and organisations will be conducted to identify relevant material. The reference lists of articles included in the review will be screened and a ‘snowball’ technique will be adopted if citations appear relevant within articles searched (Pham et al, 2014). Two searches will be conducted at 6-month intervals, in order to scope emerging research, discussion, and guidelines on this topic in the health professions. Each search will be conducted in two stages, based on the agreed search terms and databases (Peters et al, 2024).
Information sources
The following sources of literature have been selected:
Study selection
Following the search, all identified records will be collated and uploaded into the web-based reference manager EndNote X7.8 and duplicate citations removed. Articles identified in these searches will be identified as those to include, those to exclude, and those to discuss (Peters et al, 2024). Screening will take place on two levels. First, titles and abstracts will be screened by two independent reviewers for assessment against the inclusion criteria for the review, in keeping with the JBI recommended key elements for a scoping review protocol that at least two reviewers should be identified before the start of the review process. The full text of selected citations will subsequently be assessed in detail against the inclusion criteria by two independent reviewers. Reasons for exclusion of full-text articles that do not meet the inclusion criteria will be recorded and reported in the scoping review. Any disagreements that arise between the reviewers at each stage of the selection process will be resolved through discussion with a third reviewer who will serve as an arbitrator in the final selection of articles (Peters et al, 2024). The inclusion of multiple reviewers increases reliability (Munn et al, 2018), which is strengthened by the use of reviewers from different disciplines (Cacchione, 2016). The results of the search will be reported in full in the final scoping review and presented in a PRISMA Extension for Scoping Reviews (PRISMA-ScR) flow diagram (Tricco et al, 2018).
Data extraction
Data will be extracted from articles included in the scoping review by two independent reviewers using a pre-developed data extraction tool. The data extracted will include specific details about the healthcare disciplines involved, residual volume, IV infusion, methods and key findings relevant to the review question. The draft data extraction tool may be modified and revised as necessary during the process of extracting data from each included article. Modifications will be detailed in the full scoping review. Any disagreements that arise between the reviewers will be resolved through discussion, or via arbitration by a third reviewer (Peters et al, 2024). Authors of articles will be contacted to request missing or additional data, where possible.
Data presentation
The extracted data will be presented in diagrammatic or tabular form in a manner that aligns with the objective of this scoping review (Peters et al, 2024). This will include the name of the authors or the organisation/society that developed the document, the year of publication, the country of origin and the aims/purpose of the document (Peters et al, 2015). Data extraction will also include the type of document (i.e., research study, standards, recommendations etc) and references to management of residual volume on the completion of a medication infusion. Within synthesis and analysis of the data, a narrative summary will accompany the tabulated results and will describe how the results relate to the review objectives and question (Cacchione, 2016; Peters et al, 2024). This will provide a historical view of the healthcare research in this topic, will describe healthcare societies and associations who have developed guidelines, and describe research findings, and standards of practice.
Conclusion
To the authors' knowledge, this scoping review is the first attempt to conduct a review of studies examining residual volume, after the ‘rapid response’ review conducted in 2014 by the Canadian Agency for Drugs and Technologies in Health. The findings will be helpful in determining current practices, and the significance of these practices to the delivery of the accurate and complete dose of prescribed medication. It has the potential to advance the science and practice of intermittent medication infusions. It will also inform stakeholders in antimicrobial resistance and antimicrobial stewardship on developing evidence-based competencies to deliver full-dose antimicrobial medicines. It will contribute to the current discussion in the literature regarding this practice. In particular, it will assist in identifying gaps in the management of residual volume, and assist in directing future research on the topic. Findings from the scoping review will be disseminated through a published report in a peer reviewed journal, and through conference presentations. BJN