NR 516 Week 3 Article Summary of a Flushing Trial Example

Article Summary: Keogh and Colleagues' Pilot Trial of Flushing Peripheral Catheters Every 6 or 24 Hours With 3 or 10 Milliliters, Reported So a Colleague Could Answer Questions Without Opening It

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College of Nursing, Chamberlain University

NR 516: Basic Research and Evidence-based Practice

Instructor Name

Month Day, Year

Article Summary: Keogh and Colleagues' Pilot Trial of Flushing Peripheral Catheters Every 6 or 24 Hours With 3 or 10 Milliliters, Reported So a Colleague Could Answer Questions Without Opening It

Why This Article

This summary reports one study found in the Week 2 search: a pilot trial by Keogh et al. (2016), published in the open-access journal Trials, that compared different flushing schedules for peripheral intravenous catheters in adult hospital patients. It was chosen because it is the only trial from the search that studied adults on medical and surgical wards, the population on my unit, and because it tested how often to flush, the question behind our eight-hour routine. The summary follows the order a reader needs rather than the order the article uses, and every figure below is taken from the article itself.

Purpose

The trial had two purposes. The first was to test whether a larger trial of flushing practice would be feasible: whether patients could be screened, recruited and followed, and whether the data could be collected reliably. The second was to compare catheter failure between two flush volumes and two flush frequencies. Because it was a pilot, the authors were clear that the second purpose was exploratory and that a definitive answer would need a larger study.

Who Took Part, Where and When

The trial was run on medical and surgical wards of one large tertiary metropolitan hospital in Brisbane, Australia. Adults aged 18 or older were eligible if they had a peripheral catheter inserted within the previous 24 hours, or about to be inserted, that was expected to stay in for more than 24 hours, and if they gave written informed consent. Patients receiving continuous intravenous therapy were excluded, as were non-English-speaking patients without an interpreter. Only one catheter per patient was studied. The researchers recruited 160 patients over four months; the article was received by the journal in December 2015. Ethics approval came from the hospital's human research ethics committee and the university's, and the trial was registered with the Australian and New Zealand Clinical Trials Registry.

What Was Done

Patients were randomly assigned in equal numbers to one of four groups: 3 or 10 milliliters of normal saline, delivered at 6-hour or at 24-hour intervals. This is a factorial design, which tests two interventions, volume and frequency, at the same time. Flushes were given from syringes prepared by hand. A research nurse screened patients each day, obtained consent, performed the randomization through a centralized web-based service and communicated with ward staff. The allocation was hidden until each patient entered the study, but once assigned, the flush order could not be hidden from patients, ward staff or the research nurses.

What Was Measured

The primary outcome was catheter failure, defined as a combination of four events that end a catheter's use before therapy is finished: occlusion, infiltration, accidental dislodgement and phlebitis. Failure was expressed as a rate per 1,000 catheter hours, which allows catheters that stayed in for different lengths of time to be compared fairly. Research nurses collected data until two days after each catheter was removed, drawing on direct assessment, patient charts and the hospital's medication and pathology systems. The number of times each catheter was accessed per day, for flushes and medications combined, was also recorded.

What Moved

The average catheter stayed in for 3.1 days. Failure rates were 4.84 per 1,000 hours in the 3 mL groups and 7.44 in the 10 mL groups, and that gap fell short of significance (p = 0.06). Failure rates were 5.06 per 1,000 hours with flushing every 24 hours and 7.34 with flushing every 6 hours (p = 0.05). In regression models, neither volume nor frequency, nor the combination of the two, was significantly associated with failure.

Three factors did predict failure. Women had about twice the hazard of catheter failure (hazard ratio 2.2). Catheters in the hand or back of the wrist failed more often (hazard ratio 1.7). And each additional access per day, whether a flush or a medication, raised the hazard (hazard ratio 1.2 per access). That last finding is the most relevant to my unit: it suggests that handling a catheter more often may itself contribute to failure.

How Sure the Authors Were

The authors were cautious. Their initial comparisons pointed toward more frequent and larger flushes being associated with more failure, which runs against the belief that more flushing keeps catheters open, but the regression results were not significant. They calculated after the fact that the trial had only 40% power to detect a difference in volume and 14% for frequency, meaning it was too small to rule out real effects. They noted that the interventions could not be masked, which could bias outcome assessment, and that flushing before and after medications was not controlled. They concluded that neither larger nor more frequent flushing significantly changed failure risk, and that a larger trial was feasible and needed.

What This Summary Leaves Out

A summary is a selection, so its gaps should be stated. This one does not reproduce the trial's table of patient characteristics, such as age, reason for admission and the gauge and site of each catheter, and a colleague comparing the trial's patients with our own should read that table directly. It also does not detail the feasibility results, such as how many patients were screened for each one recruited, which matter to researchers planning a larger study more than to a nurse deciding a unit routine. Finally, it reports the article's statistics as the authors gave them; it does not re-analyze them.

What a Colleague Can Take From It

For a nurse asking whether our unit's eight-hourly flush is necessary, this study offers three things. First, in adults on medical and surgical wards, flushing every 24 hours did not produce more catheter failure than flushing every 6 hours, although the trial was too small to prove equivalence. Second, eight hours, our interval, falls between the two tested schedules, so the study does not test it directly but does bracket it. Third, the finding that each extra access raises the risk of failure suggests that unnecessary flushes may not be harmless. The study is a pilot, from one hospital in Australia, and cannot settle our practice on its own. It is a reason to look for more evidence rather than a reason to change the routine tomorrow.

References

Keogh, S., Flynn, J., Marsh, N., Mihala, G., Davies, K., & Rickard, C. (2016). Varied flushing frequency and volume to prevent peripheral intravenous catheter failure: A pilot, factorial randomised controlled trial in adult medical-surgical hospital patients. Trials, 17(1), Article 348. https://doi.org/10.1186/s13063-016-1470-6