Dear Editor,
We are writing in response to the article by Andrew Barton and board members of the UK's National Infusion and Vascular Access Society (NIVAS). ‘Intravenous infusion drug administration: flushing guidance’ (Barton et al, 2019). We contend that there is substantial evidence to support concern regarding this issue (Rout et al, 2019), and the NIVAS guidelines cite several recent publications from the UK that have raised the alarm regarding nursing management of undelivered therapeutic fluid (Cooper et al, 2018; Cousins, 2018; Furniss et al, 2018).
It is evident from research that has been conducted into intravenous intermittent infusions that a gap in clinical practice exists regarding the optimal management of residual fluid (Hoefel et al, 2008; Chan et al, 2013; Lam et al, 2013; Cooper et al, 2018; Furniss et al, 2018; Morrow, 2018; Thoele et al, 2018), and it is indeed the place of NIVAS to offer expert consensus (Barton et al, 2019). However, these guidelines underplay the significance of underdosing from non-delivery of residual volume.
Residual volume is undelivered therapeutic fluid ‘left over’ in the infusion line following completion of an intermittent intravenous infusion, which is not delivered to the patient unless actively flushed with fluid (Lam et al, 2013; Alexander and Zomp, 2015). This amount may be anything from 23 ml to 30 ml, depending on the length of the infusion administration set and the amount of fluid remaining in the drip chamber (Weeks, 2012; Lam et al, 2013; Rout et al, 2019). Cousins (2018) raises this issue as being of particular concern for small volume intermittent infusions, where the amount remaining following administration of the infusion contains a large amount of undelivered dose. The issue of non-delivery of residual fluid is therefore that of non-delivery of a substantial amount of a prescribed dose of medication, whatever that medication may be (Hoefel et al, 2008; Weeks, 2012; Alexander and Zomp, 2015; Cousins, 2018; Thoele et al, 2018). This creates three problems:
Cousins (2018) suggested that non-delivery of a prescribed order may constitute a breach of the Medicines Act 1968 (UK), and may result in the nurse having to explain in law why a full dose was not given.
NIVAS postulates that irrespective of whether or not the complete dose of drug is administered, a therapeutic level is reached in the patient's blood. NIVAS continues this rationale by stating that this therapeutic level remains until the half-life of the drug is reached, by which time the next intermittent infusion is due (Barton et al, 2019). This does not make sense. If 27 ml to 30 ml of therapeutic fluid, within a 50 ml small volume bag, remains in the infusion administration line as suggested by Weeks (2012) and Lam et al (2013), the patient will receive only 20 ml, which is 40% of the prescribed dose.
Ensuring full-dose delivery of antimicrobial medicines is essential to avoid underdosing and antimicrobial resistance. A study in Brazil found that 67% (74/111) of vancomycin infusions, administered in surgical and medical wards and intensive care units (ICUs), had undelivered therapeutic fluid remaining within the infusion tubing following completion of the infusion; in ICU alone, 85% (34/40) were incomplete (Hoefel et al, 2008). This finding has been replicated by a number of studies on loss of antimicrobial dose to residual volume (Lam et al, 2013; Cooper et al, 2018).
This is catastrophic in terms of antimicrobial medication not reaching desired minimum inhibitory concentration (MIC) at the site of infection to exert its bactericidal/bacteriostatic effects (Weeks, 2012; Jarrell et al, 2015; Cousins, 2018), and may go some way to explain the failure of antimicrobial stewardship to address antimicrobial resistance. If subtherapeutic levels of antimicrobial treatment are being used to manage an infection, it is more than likely that the pathogen will develop a resistance to the drug, rendering it useless (Hoefel et al, 2008; Weeks, 2012; Jarrell et al, 2015; European Commission, 2017; Cooper et al, 2018; Thoele et al, 2018).
Antimicrobial resistance is threatening to overturn all the gains made to modern medicine by antibiotics, and it is worrying to consider that nursing actions might be contributing to this.
The conclusion that non-delivery of residual fluid following completion of intermittent intravenous infusions poses a minimal risk to patients, and that there are few situations when it would be advantageous to flush the administration set (Barton et al), is misleading, particularly at a time in health care when antimicrobial resistance threatens any advances that have been made over the past 70 years.
The lack of recognition of the consequences of incomplete administration of a prescribed dose (Thoele, 2018), by influential bodies such as NIVAS (Barton et al, 2019), and the delay in the provision of clear guidance (Infusion Nurses Society, 2016; Royal College of Nursing, 2016) for the management of intermittent infusions regrettably sends an inaccurate message to nurses in clinical practice, and compromises patient safety.